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A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenFri, 12 Apr 2024 15:25:59 +0000Baryon Number Generation and Mass Relations in SO(10) Unified Models
https://resolver.caltech.edu/CaltechTHESIS:01302018-144721271
Authors: {'items': [{'id': 'Harvey-Jeffrey-Alan', 'name': {'family': 'Harvey', 'given': 'Jeffrey Alan'}}]}
Year: 1981
DOI: 10.7907/mv0x-zk52
<p>Two topics are discussed in this thesis. The first is the calculation of cosmological baryon number generation in the early universe. These calculations are performed for a variety of SU(5) and SO(10) unified models. The effects of superheavy fermions and charge conjugation symmetry are discussed in the context of SO(10) models. The second section contains an analysis of natural fermion mass and mixing angle relations in a grand unified model based on SO(10). These relations are used to study neutrino masses and oscillations. Appreciable mixing is found only between μ and τ neutrinos. Spinor representations of the Lorentz group and of SO(10) are described in two appendices.</p>https://thesis.library.caltech.edu/id/eprint/10657Pair Creation by Dynamic Field Configurations
https://resolver.caltech.edu/CaltechTHESIS:03222018-143018429
Authors: {'items': [{'id': 'Aoyama-Hideaki', 'name': {'family': 'Hideaki', 'given': 'Aoyama'}}]}
Year: 1982
DOI: 10.7907/d9zm-yb94
<p>This thesis deals with the dynamics of the classical configuration of a quantum field unstable due to pair creation. The effective action method is developed first to treat such problems for a simple two-field model. Physical quantities such as pair creation probabilities are related to a complex function called the "effective configuration," which is defined to minimize the effective action. Unitarity of the S-matrix is verified at the lowest order of the weak-field approximation. At the same order, the real valued vacuum expectation value of the quantum field, named the "real configuration," is constructed in terms of the effective configuration. An integro-differential equation for the real configuration is given and is used to show that the real configuration is causal, while the effective configuration is not. Two practical applications of the effective action method are discussed. The first deals with pair creation in an anisotropic universe, and the "real geometry" is given in terms of the "effective geometry" in the small anisotropy limit. The second deals with expanding vacuum bubbles. Corresponding to three possible situations, three kinds of field equations for each of the effective configuration and the real configuration are obtained. The behavior of the bubble is also studied by a semi-classical method, and one of the three situations is suggested to be plausible.</p>https://thesis.library.caltech.edu/id/eprint/10779Mass-Gaps in Lattice Field Theories
https://resolver.caltech.edu/CaltechTHESIS:05152018-114910943
Authors: {'items': [{'id': 'Gupta-Rajan', 'name': {'family': 'Gupta', 'given': 'Rajan'}, 'show_email': 'NO'}]}
Year: 1982
DOI: 10.7907/w3cz-2v27
<p>In this thesis we discuss two methods for calculating the mass-spectrum in field theories using Monte Carlo Methods. A Hamiltonian variational method is developed and checked on the 0(3) non-linear sigma model in 1+1 dimensions. The mass-gap is also· found from the 2-point correlation function and some improvements to this method are suggested. Both methods give reliable results for the lattice theory. The connection between the lattice 0(3) spin-model and the continuum theory is explored in detail.</p>https://thesis.library.caltech.edu/id/eprint/10889The Isotopic Composition of Energetic Particles Emitted from a Large Solar Flare
https://resolver.caltech.edu/CaltechTHESIS:10092014-135300222
Authors: {'items': [{'id': 'Spalding-John-David', 'name': {'family': 'Spalding', 'given': 'John David'}, 'show_email': 'NO'}]}
Year: 1983
DOI: 10.7907/dt5j-0t88
<p>We report measurements of isotope abundance ratios for 5-50 MeV/nuc nuclei from a large solar flare that occurred on September 23, 1978. The measurements were made by the Heavy Isotope Spectrometer Telescope (HIST) on the ISEE-3 satellite orbiting the Sun near an Earth-Sun libration point approximately one million miles sunward of the Earth. We report finite values for the isotope abundance ratios <sup>13</sup>C/<sup>12</sup>C, <sup>15</sup>N/<sup>14</sup>N, <sup>18</sup>O/<sup>16</sup>O, <sup>22</sup>Ne/ <sup>20</sup>Ne, <sup>25</sup>Mg/<sup>24</sup>Mg, and <sup>26</sup>Mg/<sup>24</sup>Mg, and upper limits for the isotope abundance ratios <sup>3</sup>He/<sup>4</sup>He, <sup>14</sup>C/<sup>12</sup>C, <sup>17</sup>O/<sup>16</sup>O, and <sup>21</sup>Ne/<sup>20</sup>Ne.</p>
<p>We measured element abundances and spectra to compare the September 23, 1978 flare with other flares reported in the literature. The flare is a typical large flare with "low" Fe/O abundance (≤ 0.1).</p>
<p>For <sup>13</sup>C/<sup>12</sup>C, <sup>15</sup>N/<sup>14</sup>N, <sup>18</sup>O/<sup>16</sup>O, <sup>25</sup>Mg/ <sup>24</sup>Mg, and <sup>26</sup>Mg/<sup>24</sup>Mg, our measured isotope abundance ratios agree with the solar system abundance ratios of Cameron (1981). For neon we measure <sup>22</sup>Ne/<sup>20</sup>Ne = 0.109 + 0.026 - 0.019, a value that is different with confidence 97.5% from the abundance measured in the solar wind by Geiss at al. (1972) of <sup>22</sup>Ne/<sup>20</sup>Ne = 0.073 ± 0.001. Our measurement for <sup>22</sup>Ne/<sup>20</sup>Ne agrees with the isotopic composition of the meteoritic component neon-A.</p>
<p>Separate arguments appear to rule out simple mass fractionation in the solar wind and in our solar energetic particle measurements as the cause of the discrepancy in the comparison of the apparent compositions of these two sources of solar material.</p>https://thesis.library.caltech.edu/id/eprint/8687Nucleon Structure Functions from ν_µ-Fe Interactions and a Study of the Valence Quark Distribution
https://resolver.caltech.edu/CaltechTHESIS:04082013-111418042
Authors: {'items': [{'id': 'Purohit-Milind-Vasant', 'name': {'family': 'Purohit', 'given': 'Milind Vasant'}, 'show_email': 'NO'}]}
Year: 1984
DOI: 10.7907/4RBK-RV59
<p>Data were taken in 1979-80 by the CCFRR high energy neutrino experiment at Fermilab. A total of 150,000 neutrino and 23,000 antineutrino charged current events in the approximate energy range 25 < E<sub>v</sub> < 250 GeV are measured and analyzed. The structure functions F<sub>2</sub> and xF<sub>3</sub> are extracted for three assumptions about σ<sub>L</sub>/σ<sub>T</sub>: R = 0., R = 0.1 and R = a QCD based expression. Systematic errors are estimated and their significance is discussed. Comparisons or the X and Q<sup>2</sup> behaviour or the structure functions with results from other experiments are made.</p>
<p>We find that statistical errors currently dominate our knowledge of the valence quark distribution, which is studied in this thesis. xF<sub>3</sub> from different experiments has, within errors and apart from level differences, the same dependence on x and Q<sup>2</sup>, except for the HPWF results. The CDHS F<sub>2</sub> shows a clear fall-off at low-x from the CCFRR and EMC results, again apart from level differences which are calculable from cross-sections.</p>
<p>The result for the the GLS rule is found to be 2.83 ± .15 ± .09 ± .10 where the first error is statistical, the second is an overall level error and the third covers the rest of the systematic errors. QCD studies of xF<sub>3</sub> to leading and second order have been done. The QCD evolution of xF<sub>3</sub>, which is independent of R and the strange sea, does not depend on the gluon distribution and fits yield</p>
<p>ʌ<sub>LO</sub> = 88<sup>+163</sup><sub>-78</sub> <sup>+113</sup><sub>-70</sub>MeV</p>
<p>The systematic errors are smaller than the statistical errors. Second order fits give somewhat different values of ʌ, although α<sub>s</sub> (at Q<sup>2</sup><sub>0</sub> = 12.6 GeV<sup>2</sup>) is not so different.</p>
<p>A fit using the better determined F<sub>2</sub> in place of xF<sub>3</sub> for x > 0.4 i.e., <span style="text-decoration:overline">q</span> = 0 in that region, gives</p>
<p>ʌ<sub>LO</sub> = 266<sup>+114</sup><sub>-104</sub> <sup>+85</sup><sub>-79</sub>MeV</p>
<p>Again, the statistical errors are larger than the systematic errors. An attempt to measure R was made and the measurements are described. Utilizing the inequality <span style="text-decoration:overline">q</span>(x) ≥ 0 we find that in the region x > .4 R is less than 0.55 at the 90% confidence level.</p>
https://thesis.library.caltech.edu/id/eprint/7585Study of the ψ"(3770) Using the Crystal Ball Detector
https://resolver.caltech.edu/CaltechTHESIS:12172018-095221901
Authors: {'items': [{'id': 'Partridge-Richard-Allan', 'name': {'family': 'Partridge', 'given': 'Richard Allan'}, 'show_email': 'NO'}]}
Year: 1984
DOI: 10.7907/yg5v-dv86
<p>The properties of the ψ"(3770) were studied by an experiment performed at the SPEAR e<sup>+</sup>e<sup>-</sup> colliding beam facility using the Crystal Ball detector. The unique abilities of the Crystal Ball, a highly segmented NaI detector that specializes in precisely measuring the energy and direction of photons, were used to make several new measurements.</p>
<p>The hadron cross section was measured at 23 different center of mass energies in the vicinity of the ψ". The ψ" is clear1y visib1e as a peak in the cross section near E<sub>cm</sub> = 3770 MeV. The ψ" resonance parameters were determined by fitting a modified Breit-Wigner line shape to the observed hadron cross section. The ψ" mass, partial width to e<sup>+</sup>e<sup>-</sup>, and total width were measured to be 3768±5 MeV, 283±70 eV, and 34±8 MeV, respectively.</p>
<p>The inclusive photon spectrum of the ψ" was examined for structure. Harrow peaks were observed in the spectrum due to the radiative production of ψ and ψ' mesons. The integrated hadron cross sections were measured to be 16±5 nb-GeV and 5.2±1.7 nb-Gev for the ψ and ψ', respectively. No other statistically significant structure was observed.</p>
<p>The decays of the ψ" were used to search for D° mesons decaying into four-photon and six-photon final states. No evidence for these decays was found, and the following branching ratio limits were set (90% CL): BR(D° → π°π°) < 0.28%, BR(D°→ η°π°) < 0.74%, BR(D° → ηη) < 1.0%., BR(D°→π°π°π°) < 1.6%, BR(D° → ηπ°π°) < 6.6%, and BR(D° → K°π°) < 7.6%.</p>https://thesis.library.caltech.edu/id/eprint/11318A Systematic Study of the Decays of Charmed D Mesons
https://resolver.caltech.edu/CaltechTHESIS:01312019-122402912
Authors: {'items': [{'id': 'Hauser-Jay', 'name': {'family': 'Hauser', 'given': 'Jay'}, 'show_email': 'NO'}]}
Year: 1985
DOI: 10.7907/g0wf-ny80
<p>A large sample of D mesons, produced by the decay of the Ψ(3770) and observed by the Mark III detector at SPEAR, forms the basis for a study of the decays of charmed D<sup>+</sup> and D<sup>0</sup> mesons. Many Cabibbo-allowed and Cabibbo-suppressed decays are observed. When normalized by a new, absolute technique, the branching ratios appear significantly higher than those reported by previous experiments. No evidence is found for specific final states from D<sup>0</sup> decay which are indicative of non-spectator W-exchange diagrams: limits are quoted. Finally, the inclusive semileptonic branching fractions of charged and neutral D mesons are measured by observation of electrons in the recoil from fully reconstructed hadronic D decays of known charm. By neglecting the contribution of Cabibbo-suppressed decays to the total decay widths, the ratio of these branching fractions can be interpreted as the ratio of D<sup>+</sup> and D<sup>0</sup> lifetimes, thus confirming the inequality of lifetimes observed by direct decay length experiments. The observed pattern of hadronic decays appears to favor modification of the spectator model over non-spectator processes as the main source of the lifetime difference.</p>https://thesis.library.caltech.edu/id/eprint/11368Chiral Anomalies and the Chiral Lagrangian
https://resolver.caltech.edu/CaltechTHESIS:01312019-173857612
Authors: {'items': [{'id': 'Sonoda-Hidenori', 'name': {'family': 'Sonoda', 'given': 'Hidenori'}, 'show_email': 'NO'}]}
Year: 1985
DOI: 10.7907/xg77-hd79
<p>The subject of this thesis is some implications of chiral anomalies for chiral Lagrangians. The thesis consists of three parts:</p>
<p>In the first part, a somewhat heuristic discussion of the topological meaning of anomalies is given in the framework recently introduced by Alvarez. Its application to the sigma model anomalies is also given.</p>
<p>In the second part, the incorporation of chiral anomalies into the chiral Lagrangian is discussed in a simple manner. The Wess-Zumino term and the sigma model anomalies for the effective theory are explained.</p>
<p>Finally in the third part, as an implication of chiral anomalies, the chiral soliton model is described. Its relation to QCD in large N is discussed in detail. Quantization of the soliton is done in the path integral formalism.</p>https://thesis.library.caltech.edu/id/eprint/11376Chiral Perturbation Theory and the Weak Interaction
https://resolver.caltech.edu/CaltechTHESIS:08042017-160047213
Authors: {'items': [{'id': 'Bijnens-Johan-Lambert', 'name': {'family': 'Bijnens', 'given': 'Johan Lambert'}, 'show_email': 'NO'}]}
Year: 1985
DOI: 10.7907/64qa-xw17
<p>We study the interface between the standard six-quark model and the observed low-energy weak phenomena. The main processes discussed are weak decays of kaons and hyperons. We study first the low-energy effective weak Hamiltonian at the quark level. This is derived using the renormalization group in leading logarithmic approximation.</p>
<p>Then some properties of this effective weak Hamiltonian that can be derived using chiral perturbation theory are studied. A review of chiral perturbation theory is included.</p>
<p>This formalism is used to study the relation between K̅<sup>0</sup>K<sup>0</sup> mixing and a ΔI = 3/2 decay. We find that the logarithmic corrections to this relation are large, making it unreliable. The same formalism is used to discuss a relation between Kππ, Kπ and K-vacuum matrix elements used in most attempts to compute the Kππ matrix element relevant for the ΔI = 1/2 rule. The domain of validity of this relation is determined.</p>
<p>A review of inclusion of baryons in chiral perturbation theory is given and
one-loop corrections to the Gell-Mann-Okubo relation; semileptonic hyperon decays and nonleptonic S and P wave decays are calculated. All corrections are small except the nonleptonic P wave decays and one S wave decay. The corrections to the Lee-Sugawara relation are large as a consequence of the latter.</p>
<p>Some predictions beyond chiral perturbation theory can be made within the soliton model of baryons. F/D ratios are predicted for hyperon magnetic moments, semileptonic decays and nonleptonic S wave decays in this model.</p>https://thesis.library.caltech.edu/id/eprint/10363A Study of the Iota in Radiative J/PSI Decays
https://resolver.caltech.edu/CaltechETD:etd-10162008-153536
Authors: {'items': [{'id': 'Richman-J-D', 'name': {'family': 'Richman', 'given': 'Jeffrey David'}, 'show_email': 'NO'}]}
Year: 1985
DOI: 10.7907/09yd-ka21
<p>An analysis of the production, decay, and quantum numbers of the ι(1440) in radiative J/Ψ decays is presented. The ι(1440), because of its large production in this OZI-suppressed channel, is considered a possible gluonic bound-state, or glueball. Such states appear to be a natural consequence of the non-Abelian structure of the SU(3) color gauge group of QCD. The data, 2.7 x 10<sup>6</sup> produced J/Ψ's, were obtained using the Mark III detector at the SPEAR e<sup>+</sup>e<sup>-</sup> storage ring.</p>
<p>The spin-parity of the ι(1440) is independently determined to be 0<sup>-</sup> using two decay modes, ι → K<sup>0</sup><sub>S</sub>K<sup>±</sup>π<sup>∓</sup> and ι → K<sup>+</sup>K<sup>-</sup>π<sup>0</sup>. The technique used is based on the three-body helicity formalism, which provides a means of studying the decay angular distributions in a manner independent of the structure of the Dalitz plot. This is particularly useful in the case of ι → KK̅π, where the limited phase space makes it difficult to unambiguously identify the two-body modes. In addition, the measured angular distributions provide direct visual evidence supporting the spin-parity assignment. Measurements of the ι mass, width, and branching fractions are obtained using ι → K<sup>0</sup><sub>S</sub>K<sup>±</sup>π<sup>∓</sup>, ι → K<sup>+</sup>K<sup>-</sup>π<sup>0</sup>, and ι → K<sup>0</sup><sub>S</sub>K<sup>0</sup><sub>S</sub>π<sup>0</sup>. The relative branching fractions are consistent with the isospin 0 predictions. From a study of the KK̅π Dalitz plot, an upper limit for ι → K<sup>*</sup>K̅+ c.c. is obtained. These results are discussed in the context of the current experimental status of the E(1420).</p>
<p>Upper limits are presented for B(ι → ηππ), B(ι → δπ → ηππ), B(ι → KK̅ππ), and B(ι → ρππ). The limit on B(ι → δπ → ηππ) appears to be inconsistent with a large value of B(ι → δπ → KK̅π). However, the very uncertain status and properties of the δ(980) make it difficult to pinpoint the source of this inconsistency. Together, these upper limits provide evidence that, apart from a possible ι → ρρ signal, KK̅π is the dominant ι decay and that inclusive ι production is dominated by J/Ψ → γι, ι → KK̅π.</p>
<p>The double radiative channels J/Ψ → γX, X → γ+ Vector, where Vector = ρ<sup>0</sup>, φ, ω are studied to probe the quark content of the object X. Many pseudoscalar mixing models predict that the ι acquires a large radiative width into γρ<sup>0</sup> through mixing with the η and η'. In the γ(γρ<sup>0</sup>) final state, a broad structure is observed in the 1.4 GeV region. Although the measured angular distributions are consistent with the pseudoscalar predictions, the central mass of this structure is below that found for the ι in the KK̅π channels. Thus, with the present limited statistics, it is unclear whether this structure should be identified with the ι. Upper limits are obtained for ι → γφ and ι → γω. Measurements are also obtained for B(J/Ψ → γη') and B(J/Ψ → γη) using the γ(γπ<sup>+</sup>π<sup>-</sup> final state. These results are compared with theoretical predictions.</p>
<p>Measurements of the hadronic decays J/Ψ → φη, ωη, and ωπ<sup>0</sup>, as well as the observation of the isospin-violating decay J/Ψ → ρ<sup>0</sup>η, are presented.</p>
<p>Finally, the two- and three-body helicity formalisms are discussed in the Appendices.</p>https://thesis.library.caltech.edu/id/eprint/4119A Study of Charged D* Mesons Produced in e⁺e⁻ Annihilation at E꜀ₘ = 29 GeV
https://resolver.caltech.edu/CaltechTHESIS:04152019-093410294
Authors: {'items': [{'id': 'Yamamoto-Hitoshi', 'name': {'family': 'Yamamoto', 'given': 'Hitoshi'}, 'show_email': 'NO'}]}
Year: 1986
DOI: 10.7907/nms8-7v38
<p>Charged D* mesons produced in e<sup>+</sup>e<sup>-</sup> annihilation at a center-of-mass energy of 29 GeV have been studied with the DELCO detector at the PEP storage ring. The selection criteria of D* candidates exploit the π/K separation capability in the momentum range from 2.6 GeV/c to 9.2 Ge VIc provided by the gas Čerenkov counter. The data correspond to an integrated luminosity of 147 pb<sup>-1</sup>.</p>
<p>We have measured the total production cross section of D*<sup>±</sup> to be [0.16±0.02(statistical)±0.02(systematic)] nb [x ≡ P<sub>D*</sub>/(E<sup>2</sup><sub>beam</sub>-M<sup>2</sup><sub>D*</sub>)<sup>1/2</sup> > 0.35], and (0.18 ± 0.02 ± 0.03) nb (x > 0) if the contribution from bottom quarks is subtracted. The branching fractions used are Br(D*<sup>+</sup> → D<sup>0</sup>π<sup>+</sup>) = 64% and Br(D<sup>0</sup> → K<sup>-</sup>π<sup>+</sup>) = 3%. The systematic errors due to the branching ratios are not included in the errors. With Br(D<sup>0</sup> → K<sup>-</sup>π<sup>+</sup>) = 4.9%, which is a recent measurement by the MARK III group, the above two cross sections become 0.10±0.02±0.02 nb (x > 0.35) and 0.11±0.02±0.02 nb (x > 0 and after the subtraction of the contribution from b quarks).</p>
<p>The charm fragmentation function is harder than that for light quarks, and the shape is found to be consistent with the prediction of the string model with a uniform string-breaking probability. Assuming the string model, the string-breaking probability is determined to be (0.019 ± 0.05 ± 0.09) GeV<sup>2</sup>.</p>
<p>We have also determined the lifetime of D<sup>0</sup> meson which is detected in the D* decay, with the result τ<sub>D<sup>0</sup></sub> = (5.3 ± 1.7<sup>+0.6</sup><sub>-0.5</sub>) x 10<sup>-13</sup> sec. Together with the semileptonic branching fraction of D<sup>0</sup> measured elsewhere, the semileptonic decay rate of D<sup>0</sup> is estimated to be (1.4 ± 0.5) x 10<sup>11</sup> sec<sup>-1</sup>, which corresponds to an effective charm quark mass of (1.54 ± 0.12) GeV/c<sup>2</sup>.</p>
<p>Using part of the D* candidates, we have set an upper limit on D<sup>0</sup>-D̅<sup>0</sup> mixing: r ≡ P(D<sup>0</sup> → D̅<sup>0</sup>)/P(D<sup>0</sup> → D<sup>0</sup> or D̅<sup>0</sup>) < 8.3% (90% c.l.), leading to a stringent limit on charm-changing neutral currents.</p>https://thesis.library.caltech.edu/id/eprint/11460A Search for Free Proton Decay, and Nucleon Decay in O¹⁶, Using the Invariant Mass and Momentum of Exclusive Final States
https://resolver.caltech.edu/CaltechTHESIS:08302019-091520851
Authors: {'items': [{'id': 'Blewitt-Geoffrey', 'name': {'family': 'Blewitt', 'given': 'Geoffrey'}, 'show_email': 'NO'}]}
Year: 1986
DOI: 10.7907/kabk-rb61
<p>Existing Grand Unified Theories predict a free proton lifetime which would be experimentally accessible. If discovered, a study of the branching modes of the proton could provide indicators to the correct theory. The lifetime of a proton is probably longer in a nucleus, though by no more than an order of magnitude.</p>
<p>A search for nucleon decay was performed for 37 possible branching modes of nucleons in water, and 14 branching modes of free protons from the hydrogen in water. The data was taken from the I.M.B. water Cherenkov detector, which contains 3,300 metric tons in the fiducial volume. The only significant background to proton decay comes from atmospheric neutrino interactions. An initial search used the visible energy, anisotropy, and number of muon decays of events. A more sophisticated search automatically selected events with two clear tracks of opening angle > 115°. The invariant mass and momentum of these events were calculated for 16 nucleon decay hypotheses.</p>
<p>In 417 livedays, 326 events were reconstructed in the fiducial volume at a rate, and with visible characteristics consistent with atmospheric neutrino interactions. No significant excess of events was found for any nucleon decay mode. For the visible energy and anisotropy analysis, partial lifetime limits at the 90% confidence level were set in the range 10<sup>31-32</sup> years for nucleons, assuming that the free and bound lifetimes are similar. With the free proton decay analysis, limits were set in the range 10<sup>30-32</sup> years. The number of clean two-prong events was found to be 4.0 ± 1.1%. The background estimates gave a mean estimate of 4.1 ± 0.3%. Partial lifetime limits at the 90% confidence level were set for both free protons, and bound plus free nucleons at 10<sup>32</sup> years for <i>N</i> → lepton + γ/π, and 10<sup>31</sup> years for <i>N</i> → lepton + η/ρ/ω.</p>
<p>A framework for converting the results into model-dependent total lifetime limits is described, and limits for SU(5) are explicitly calculated. Our results imply an SU(5) model-dependent limit of 4 x 10<sup>31</sup> years (90% C.L.) on the total proton lifetime, where effects of the nucleus on the decay rate have been accounted for. This is incompatible with theoretical predictions. The derived limits should also provide useful constraints on other Grand Unified Theories.</p>https://thesis.library.caltech.edu/id/eprint/11773The Properties of Semileptonic Decays of Charmed D Mesons
https://resolver.caltech.edu/CaltechTHESIS:08302019-143806077
Authors: {'items': [{'id': 'Coffman-Daniel-Mark', 'name': {'family': 'Coffman', 'given': 'Daniel Mark'}, 'show_email': 'NO'}]}
Year: 1987
DOI: 10.7907/4be7-sc20
<p>The MARK III collaboration has collected a large sample of D mesons produced at the Ψ(3770) resonance. The reconstruction of several thousand hadronic D decays makes possible for the first time the reconstruction of exclusive semileptonic D decays. Absolute branching ratios are measured for the nine decays D<sup>0</sup> → K<sup>-</sup> e<sup>+</sup> ν<sub>e</sub>, D<sup>0</sup> → K<sup>-</sup> π<sup>0</sup> e<sup>+</sup> ν<sub>e</sub>, D<sup>0</sup> → K̅<sup>0</sup> π<sup>-</sup> e<sup>+</sup> ν<sub>e</sub>, D<sup>+</sup> → K̅<sup>0</sup> e<sup>+</sup> ν<sub>e</sub>, D<sup>+</sup> → K<sup>-</sup> π<sup>+</sup> e<sup>+</sup> ν<sub>e</sub>, D<sup>0</sup> → π<sup>-</sup> e<sup>+</sup> ν<sub>e</sub>, D<sup>0</sup> → K<sup>-</sup> μ<sup>+</sup> ν<sub>μ</sub>, D<sup>0</sup> → K̅<sup>0</sup> π<sup>-</sup> μ<sup>+</sup> ν<sub>μ</sub>, and D<sup>+</sup> → K̅<sup>0</sup> μ<sup>+</sup> ν<sub>μ</sub>. The sums of the exclusive branching ratios are in good agreement with the inclusive semileptonic branching ratios measured by the MARK III. The rate of the Cabibbo-suppressed decays is consistent with the predicted rate. The contribution of the K<sup>*</sup>(892) to the K-π invariant mass spectrum for decays of the type D → K π e<sup>+</sup> ν<sub>e</sub> is found to be about 55%. The vector form factor in the decays D<sup>0</sup> → K<sup>-</sup> e<sup>+</sup> ν<sub>e</sub> and D<sup>0</sup> → K<sup>-</sup> μ<sup>+</sup> ν<sub>μ</sub> is measured and found to be consistent with a simple pole form.</p>https://thesis.library.caltech.edu/id/eprint/11781Studies on Flagellar Rotation: The Angular Symmetry, the Stall Torque, and the Proton Consumption of the Bacterial Flagellar Motor
https://resolver.caltech.edu/CaltechTHESIS:04052017-093614620
Authors: {'items': [{'id': 'Meister-Markus', 'name': {'family': 'Meister', 'given': 'Markus'}, 'orcid': '0000-0003-2136-6506', 'show_email': 'NO'}]}
Year: 1987
DOI: 10.7907/rv9w-sm36
<p>Flagellated bacteria propel themselves through an aqueous medium by rotating their helical flagellar filaments. The torque required for this motion is generated in the flagellar motor, which anchors the filament to the cell wall. The motor measures only about 25 nm in diameter, and electron micrographs of the isolated organelle show several rings arranged on a rod, which is connected to the filament by a curved hook. Flagellar rotation is driven by the protonmotive force across the cytoplasmic membrane. In recent years, a motile strain of <i>Streptococcus</i> has emerged as the organism of choice in studies of the flagellar motor, chiefly because its protonmotive force is easily manipulated. Since this bacterium lacks endogenous energy reserves, it can be starved until no metabolic protonmotive force remains. The grampositive cell wall leaves the cytoplasmic membrane accessible to ionophores, which facilitates the generation of artificial proton gradients. Flagellar rotation can be visualized by tethering a bacterium to a glass surface by one of its flagellar filaments, which causes the cell body to spin about the point of attachment. Recently it has also become possible to measure the motor's rotation rate in swimming cells. This thesis contains a variety of functional studies as well as some theoretical considerations of torque generation in the flagellar motor.</p>
<p>The rotational angular symmetry of the motor was probed by a study of the angular positions at which it can stop. Only 5 or 6 discrete stopping angles were found. This constraint may result from static interactions between the rod of the motor and components of the cell wall.</p>
<p>A technique was developed to measure the external torque required to stop flagellar rotation. This stall torque did not depend noticeably on the motor's angular position. It was equal to the running torque measured in a rotating tethered cell. In particular, a decrease in the running torque at very low and very high pH, as well as its saturation at large protonmotive force, were also observed for the stall torque. These results show that the running torque is not limited by the rates of torque-generating processes associated with motor rotation. The apparent saturation of the torque as a function of protonmotive force seems to result from difficulties in generating large potassium diffusion potentials. Similarly, the artificially generated protonmotive force might be affected at extreme values of the pH.</p>
<p>This thesis also reports the first sucessful measurements of the proton flux associated with flagellar rotation. These studies required an investigation of the total proton flux through the cytoplasmic membrane. An unusually large proton conductance was found, ca 10 times higher than the values reported for the membrane of <i>Streptococcus lactis</i>. After energization with an artificial, inwardly directed protonmotive force the rate of proton uptake by the cells decreased by a factor of 10 in 30 to 60 s with roughly exponential time course. Under certain conditions this influx was followed by slow extrusion of protons, part of which could be mediated by passive antiport of protons against other cations. Exchange of H<sup>+</sup> for Na<sup>+</sup> and Li<sup>+</sup> was observed directly. The time course of proton movements accelerated by a factor of 6 as the temperature varied from 16°C to 32°C. The rate of proton uptake was reduced by about 25% through the action of DCCD, an inhibitor of the proton-translocating ATPase. In D<sub>2</sub>O the flux of hydrogen ions was ca. 20% lower than in H<sub>2</sub>O.</p>
<p>Only a small fraction of the initial proton influx was associated with flagellar rotation, as determined from measurements on cells whose motors could not turn because their filaments were cross-linked with an antibody. The rotation-dependent component of the proton flux varied proportionally to the speed of the motor, with ca. 1100 protons transferred in one revolution of the filament. These observations support the hypothesis that proton flux and flagellar rotation are tightly coupled by the flagellar motor in a constant stoichiometric ratio. Measurements of the torque acting on the filament suggest that the conversion from electrochemical energy to mechanical work occurs with an efficiency of the order of 5% in swimming cells. At the low speeds of tethered cells the motor generates a larger torque, and the efficiency might be close to unity.</p>
<p>A hypothetical mechanism for torque generation, originally proposed in 1982, is analyzed in detail and compared to other models found in the literature. Its predictions are at odds with the experimental evidence presented in this thesis. However, the model can be altered by the assumption that the conduction of protons through the motor limits its rotation rate at very low torque. In particular, it is suggested that protons may be transferred across the membrane along chains of discrete binding sites. This could account for the strong dependence of the motor's maximal speed on the temperature and the hydrogen isotope.</p>
https://thesis.library.caltech.edu/id/eprint/10126Experimental Tests of QCD and Fragmentation Models in Electron-Positron Annihilation
https://resolver.caltech.edu/CaltechTHESIS:03072013-134658154
Authors: {'items': [{'id': 'Stone-Howard-D', 'name': {'family': 'Stone', 'given': 'Howard D.'}, 'show_email': 'NO'}]}
Year: 1988
DOI: 10.7907/2ezn-qk36
<p>This thesis presents a detailed study of the hadronic data obtained with the MARK J detector from e⁺e⁻ annihilation. The predictions of several new combinations of Monte Carlo parton generators and fragmentation schemes have been tuned and compared directly to the data.</p>
<p>A study, performed in the limit of perfect detector resolution and efficiency, has shown that the string effect, which some groups claimed to have observed, cannot be attributed to soft gluon coherence effects occurring at the soft perturbative stage of the event evolution.</p>
<p>It is found that all the fragmentation schemes employing the string formalism are unable to correctly describe the form of the Thrust and Energy-Energy Correlation distributions obtained with the high energy data above 40 GeV center-of-mass energy. The problems encountered have their origins in the modelling of the fragmentation process rather than in the perturbative QCD aspects of the models. All the models investigated, however, are capable of describing a broad range of distributions at the lower center-of-mass energies.</p>
<p>No evidence for the presence of the string effect has been found in the MARK J data.</p>
<p>The new fragmentation models have been used to extract values for the strong coupling constant from the data. The systematic uncertainties assigned to previous α₈ measurements have been re-assessed in the light of this study, and it has been found that previous error assignments require no adjustment.</p>
<p>A recent 2nd order calculation for the three-jet partial cross section has been investigated and converted into a form where it can be directly compared to previous calculations. The calculations are found to be in excellent agreement, and it is concluded that the systematic errors that should be assigned to α₈ measurements due to theoretical uncertainties are negligible.</p>
<p>Motivated by the observation of an excess number of low thrust inclusive muon events at the highest PETRA energies, the MARK J hadronic data above 46.3 GeV has been compared to a lower energy data sample. The presence of new phenomena in the highest energy hadronic data has been ruled out at the level of available statistics.</p>
<p>A brief study of the characteristics to be expected at LEP energies for events originating in the production of top quarks has been made, and a method for isolating a top-enriched sample has been investigated.</p>
https://thesis.library.caltech.edu/id/eprint/7502A Measurement of Inclusive Quasi-Elastic Electron Scattering Cross Sections at High Momentum Transfer
https://resolver.caltech.edu/CaltechTHESIS:06042013-092346016
Authors: {'items': [{'id': 'Potterveld-David-Henry', 'name': {'family': 'Potterveld', 'given': 'David Henry'}, 'show_email': 'NO'}]}
Year: 1989
DOI: 10.7907/y2ef-tj92
<p>We have measured inclusive electron-scattering cross sections for targets of ⁴He, C, Al, Fe, and Au, for kinematics spanning the quasi-elastic peak, with squared, four momentum transfers (q²) between 0.23 and 2.89 (GeV/c)². Additional data were measured for Fe with q²'s up to 3.69 (GeV/c)² These cross sections were analyzed for the y-scaling behavior expected from a simple, impulse-approximation model, and are found to approach a scaling limit at the highest q²'s. The q² approach to scaling is compared with a calculation for infinite nuclear matter, and relationships between the scaling function and nucleon momentum distributions are discussed. Deviations from perfect scaling are used to set limits on possible changes in the size of nucleons inside the nucleus.</p>https://thesis.library.caltech.edu/id/eprint/7831The Decay Properties of the ψ(3770)
https://resolver.caltech.edu/CaltechTHESIS:10252013-112507352
Authors: {'items': [{'id': 'Zhu-Yanong', 'name': {'family': 'Zhu', 'given': 'Yanong'}, 'show_email': 'NO'}]}
Year: 1989
DOI: 10.7907/2c5y-sq13
The decays of the ψ(3770) resonance to final states that do not contain charmed D mesons are measured for the first time. Using a sample of 9.3pb⁻¹ of e⁺e⁻ annihilations at √s = 3.77 GeV, collected with the Mark III detector at SPEAR, we have measured the branching ratio for the decays ψ(3770) → J/ψπ⁺π⁻ and γχ<sub>J</sub>. These branching ratios together with the electronic widths of the ψ(3685) and ψ(3770) are used to determine the mixing angle between the 2³S₁ and 1³D₁ Charmonium states and are compared with a number of predictions. In addition, evidence is found for other non-DD̅ hadronic final states, such as 3π, 4π, and 5π, as well as η2π, η4π, p̅p2π and p̅p3π.https://thesis.library.caltech.edu/id/eprint/8010A Search for νₑ Appearance from Stopped π⁺ and µ⁺ Decay at LAMPF
https://resolver.caltech.edu/CaltechETD:etd-06062007-121228
Authors: {'items': [{'id': 'Fujikawa-Brian-Kurt', 'name': {'family': 'Fujikawa', 'given': 'Brian Kurt'}, 'show_email': 'NO'}]}
Year: 1990
DOI: 10.7907/9e8k-2p03
<p>We report on a recent search for ν̅ₑ appearance from stopped π⁺ → µ⁺ν<sub>µ</sub> and µ⁺ → e⁺νₑν̅<sub>µ</sub> decay made by the LAMPF experiment E645. The appearance of ν̅ₑ may occur from ν̅<sub>µ</sub> → ν̅ₑ, νₑ → ν̅ₑ<sub>L</sub>, or ν<sub>µ</sub> → ν̅ₑ<sub>L</sub> oscillations. Appearance may also occur from rare µ⁺ → e⁺ν̅ₑν<sub>µ</sub> decay, which is allowed by a multiplicative lepton charge conservation law. The neutrino energies range from E<sub>ν</sub> to 52.8MeV. The neutrino detector, which is located 26.1 meters from the neutrino source, consists of a segmented liquid scintillator and proportional drift tube central detector surrounded by both active and passive shielding. The central detector detects ν̅ₑ through the ν̅ₑp → ne⁺ Charge Current (CC) reaction, which is signaled by the direct detection of the final state positron and neutron. The hydrogen-rich liquid scintillators act as free proton targets for the ν̅ₑp CC reaction. The neutrons are detected through radiative neutron capture on gadolinium. We find no evidence for ν̅ₑ appearance in the first year of running. New limits on the ν̅<sub>µ</sub>, ν̅ₑ, ν<sub>µ</sub> → ν̅ₑ oscillation parameters and the rare µ⁺ → e⁺ν̅ₑν<sub>µ</sub> decay branching ratio are presented.</p>https://thesis.library.caltech.edu/id/eprint/2480Resonant Substructure in Kπππ Decays of D Mesons
https://resolver.caltech.edu/CaltechETD:etd-06062007-122309
Authors: {'items': [{'id': 'DeJongh-Don-Frederic', 'name': {'family': 'DeJongh', 'given': 'Don Frederic'}, 'show_email': 'NO'}]}
Year: 1990
DOI: 10.7907/0wda-j731
<p>We determine the resonant substructure of D → K̅πππ decays using a five-dimensional maximum likelihood technique to extract the relative fractions and phases of the amplitudes contributing to the K⁻π⁺π⁺π⁻, K̅⁰π⁺π⁺π⁻, and K̅⁻π⁺π⁺π⁰ final states. We find that two-body decay modes account for about 75% of these decays. We obtain branching ratios for D → K̅a₁, D → K̅*ρ, D → K̅₁(1270)π, D → K̅₁(1400)π, and D⁰ → K̅⁰ω decay modes, as well as several three and four-body decay modes. In the case of D → K̅a₁ and D → K̅*ρ, we obtain the branching ratios for all three possible isospin combinations, enabling us to extract the isospin 1/2 and 3/2 amplitudes. This allows us to eliminate the ambiguity due to phase shifts between the isospin amplitudes when comparing our results with theoretical models. We find that the isospin 3/2 amplitudes are suppressed relative to the isospin 1/2 amplitudes, confirming that an understanding of the lifetime difference of the D⁰ and D⁺ depends on an understanding of two-body hadronic decays.</p>
<p>For the D → K̅*ρ decay modes, we obtain detailed information on the polarization of the K̅* and ρ. This enables us to obtain information on form-factors for D → K̅* and D → ρ transitions, within the context of the factorization hypothesis. Comparison of our results on D → K̅*ρ decays with recent results on semileptonic decays allows us to test the factorization hypothesis.</p>https://thesis.library.caltech.edu/id/eprint/2481Measurement of the Leptonic Branching Fraction of the Dₛ Meson and Determination of Its Decay Constant
https://resolver.caltech.edu/CaltechTHESIS:04202020-172701960
Authors: {'items': [{'id': 'Kelsey-Michael-Henderson', 'name': {'family': 'Kelsey', 'given': 'Michael Henderson'}, 'show_email': 'NO'}]}
Year: 1996
DOI: 10.7907/x5qg-g497
<p>Between February 1992 and June 1994, the Beijing Spectrometer (BES) experiment collected 24.5 pb⁻¹ of data in e⁺e⁻ collisions at a center of mass energy of 4.03 GeV, above threshold for production of Dₛ⁺Dₛ⁻ meson pairs. In this thesis, these data are searched for Dₛ⁺Dₛ⁻ events by identifying sets of charged tracks consistent with the decay channels Dₛ → Φπ,Φ → K⁺K⁻; Dₛ → K*⁰K,K*⁰ → K⁺π⁻; or Dₛ → K⁰<sub>S</sub>K,K⁰<sub>S</sub> → π⁺π⁻. A global maximum-likelihood technique is used, which combines particle identification detector data and a kinematic fit to each decay hypothesis, for maximum sensitivity. A sample of 190 candidates is found in the mass range 1958.5-1978.5 MeV/c², of which 76.9 ± 13.8 are estimated (from a fit to 1097 combinations with 1800 < m < 2015 MeV /c²) to be true e⁺e⁻ → Dₛ⁺Dₛ⁻ events.</p>
<p>This event sample is searched for leptonic decays of the Dₛ meson in the channels Dₛ → µν<sub>µ</sub> and Dₛ → τν<sub>τ</sub> (with τ → µν̅<sub>µ</sub>ν<sub>τ</sub> → eν̅<sub>e</sub>ν<sub>τ</sub>, or τ → πν<sub>τ</sub>). Five candidate decays are found. A likelihood function is formed as a product over the candidate events, where each contributes a sum over all of the leptonic decay channels, weighted according to the likelihoods of the particle identifications and the kinematics of the decay. This likelihood function is maximized with respect to the branching fraction B(Dₛ → µν<sub>µ</sub>), or the Dₛ pseudoscalar decay constant f<sub>Dₛ</sub>, with the results</p>
<p>B(Dₛ → µν<sub>µ</sub>) = .75<sup>+1.23</sup><sub>-.47</sub> (stat) ± .06 (syst) %,</p>
<p>f<sub>Dₛ</sub> = 308<sup>+164</sup><sub>-189</sub> (stat) ± 12 (syst) MeV.</p>
<p>Comparison of the measured value of f<sub>Dₛ</sub> with other experimental determinations and with a variety of theoretical models is discussed, with implications for constraining those models.</p>https://thesis.library.caltech.edu/id/eprint/13678A Precision Measurement of the Weak Mixing Angle in Møller Scattering at Low Q₂
https://resolver.caltech.edu/CaltechETD:etd-05272004-172049
Authors: {'items': [{'email': 'markj@slac.stanford.edu', 'id': 'Jones-Gary-Mark', 'name': {'family': 'Jones', 'given': 'Gary Mark'}, 'show_email': 'NO'}]}
Year: 2004
DOI: 10.7907/S506-PZ85
<p>The electroweak theory has been probed to a high level of precision at the mass scale of the Z<sup>o</sup> through the joint contributions of LEP at CERN and the SLC at SLAC. The E158 experiment at SLAC complements these results by measuring the weak mixing angle at a Q<sup>2</sup> of 0.026 (GeV/c)<sup>2</sup>, far below the weak scale.</p>
<p>The experiment utilizes a 48 GeV longitudinally polarized electron beam on unpolarized atomic electrons in a target of liquid hydrogen to measure the parity-violating asymmetry A<sup>PV</sup> in Moller scattering.</p>
<p>The tree-level prediction for A<sup>PV</sup> is proportional to 1-4sin<sup>2</sup>θ<sub>W</sub>. Since sin<sup>2</sup>θ<sub>W</sub> is approximately 0.25, the effect of radiative corrections is enhanced, allowing the E158 experiment to probe for physics effects beyond the Standard Model at the TeV scale.</p>
<p>This work presents the results from the first two physics runs of the experiment, covering data collected in the year 2002. The parity-violating asymmetry A<sup>PV</sup> was measured to be <center>A<sup>PV</sup> = -158 ppb +/- 21 ppb (stat) +/- 17 ppb (sys).</center> The result represents the first demonstration of parity violation in Moller scattering. The observed value of A<sup>PV</sup> corresponds to a measurement of the weak mixing angle of <center>sin<sup>2</sup>θ<sub>W</sub><sup>eff</sup> = 0.2380 +/- 0.0016 (stat) +/- 0.0013 (sys),</center> which is in good agreement with the theoretical prediction of <center>sin<sup>2</sup>θ<sub>W</sub><sup>eff</sup> = 0.2385 _+/- 0.0006 (theory).</center>
</p>https://thesis.library.caltech.edu/id/eprint/2138Measurement of Branching Fractions and Mass Spectra in B → Kππγ Decays
https://resolver.caltech.edu/CaltechETD:etd-05292006-225405
Authors: {'items': [{'email': 'alex@alexsamuel.net', 'id': 'Samuel-Alexander', 'name': {'family': 'Samuel', 'given': 'Alexander'}, 'show_email': 'NO'}]}
Year: 2006
DOI: 10.7907/JNY6-XG69
We present a measurement of the branching fractions of the exclusive radiative penguin processes B to K pi pi gamma in a sample of 232 million e+ e- to B Bbar decays recorded by the BaBar detector at the PEP-II asymmetric-energy storage ring. We reconstruct four final states: K+ pi- pi+, K+ pi- pi0, Ks pi+ pi-, and Ks pi+ pi0, where Ks to pi+ pi-, in the range m(K pi pi) < 1.8 GeV/c^2. We measure the branching fractions BR(B+ to K+ pi- pi+ gamma) = (2.95 +- 0.13 (stat.) +- 0.19 (syst.)) x 10^-5, BR(B0 to K+ pi- pi0 gamma) = (4.07 +- 0.22 (stat.) +- 0.31 (syst.)) x 10^-5, BR(B0 to K0 pi+ pi- gamma) = (1.85 +- 0.21 (stat.) +- 0.12 (syst.)) x 10^-5, and BR(B+ to K0 pi+ pi0 gamma) = (4.56 +- 0.42 (stat.) +- 0.30 (syst.)) x 10^-5.https://thesis.library.caltech.edu/id/eprint/2243Dalitz Plot Analysis of the Decay B± → K±K±K∓
https://resolver.caltech.edu/CaltechETD:etd-03312006-135838
Authors: {'items': [{'id': 'Dvoretskii-Alexei', 'name': {'family': 'Dvoretskii', 'given': 'Alexei'}, 'show_email': 'NO'}]}
Year: 2006
DOI: 10.7907/7HTG-0W17
We perform an analysis of the three-body charmless decay B+ -> K+K+K- using a sample of 226.0 +/- 2.5 million BB pairs collected by the BABAR detector and measure the total branching fraction and CP asymmetry to be B = (35.2 +/- 0.9 +/- 1.6) x 10-6 and A = (-1.7 +/- 2.6 +/- 1.5)%. We fit the Dalitz plot distribution using an isobar model and report the measured values of magnitudes and phases of the production coefficients. The decay dynamics is dominated by the K+K- S-wave, for which we perform a partial-wave analysis in the region m(K+K-) < 2 GeV/c2. We find no evidence of CP violation for individual components of the isobar model.https://thesis.library.caltech.edu/id/eprint/1226Radiative Leptonic B Decays
https://resolver.caltech.edu/CaltechETD:etd-01302007-083640
Authors: {'items': [{'email': 'etchen@gmail.com', 'id': 'Chen-Edward-Tann', 'name': {'family': 'Chen', 'given': 'Edward Tann'}, 'show_email': 'NO'}]}
Year: 2007
DOI: 10.7907/KNQF-1R30
We present the results of a search for B+ meson decays into gamma l+ nu, where l = e, mu. We use a sample of 232 million B Bbar meson pairs recorded at the Y(4S) resonance with the BaBar detector at the PEP-II B factory. We measure a partial branching fraction DeltaBF in a restricted region of phase space that reduces the effect of theoretical uncertainties, requiring the lepton energy to be in the range 1.875 and 2.850 GeV, the photon energy to be in the range 0.45 and 2.35 GeV, and the cosine of the angle between the lepton and photon momenta to be less than -0.36, with all quantities computed in the Y(4S) center-of-mass frame.https://thesis.library.caltech.edu/id/eprint/408Search for B → (ρ/ω)γ decays at BABAR
https://resolver.caltech.edu/CaltechETD:etd-08252008-225854
Authors: {'items': [{'email': 'tim.piatenko@gmail.com', 'id': 'Piatenko-Timofei', 'name': {'family': 'Piatenko', 'given': 'Timofei'}, 'show_email': 'NO'}]}
Year: 2009
DOI: 10.7907/JFX3-1629
<p>We present the results of the search for the decays ß<sup>(0/±)</sup> ? ?<sup>(0/±)</sup>? (previously observed) and ß<sup>0</sup> ? ?? (for which currently only an upper limit exists). Together with ß ? K<sup>*</sup>? decays, B ? (?/?)? allow us to measure the ratio of CKM-matrix elements |V<sub>td</sub>/V<sub>ts</sub>|. The analysis is based on the full BaBar dataset of 424.35 fb<sup>-1</sup>, corresponding to 465 million BB pairs, and makes heavy use of multivariate classification techniques based on decision trees. We find ßR(B ? ?<sup>±</sup>? ) = (1.20+0.42-0.38±0.20)×10<sup>-6</sup>, ßR(B ? ?<sup>0</sup>?)= (0.95+0.23-0.21 ±0.06)×10<sup>-6</sup>, and ßR(B ? ??)=(0.51+0.27-0.24±0.10)×10<sup>-6</sup>, where the first error is statistical and the second is systematic. We do not observe a statistically significant signal in the latter channel and set an upper limit at ßR(B ? ??) < 0.9 × 10<sup>-6</sup> (90% C.L.). We also measure the isospin and SU(3)<sub>F</sub> violating quantities ?(B<sup>+</sup> ? ?<sup>+</sup>?)/2?(B<sup>0</sup> ? ?<sup>0</sup>?) - 1 = -0.43+0.25-0.22±0.10 and ?(B ? ??)/?(B<sup>0</sup> ? ?<sup>0</sup>?) - 1 = -0.49+0.30-0.27±0.10.</p>https://thesis.library.caltech.edu/id/eprint/3226Measurement of the Rare Transition b→sγ Using the Complete BABAR Data Set
https://resolver.caltech.edu/CaltechTHESIS:05312011-194358237
Authors: {'items': [{'email': 'ddoll2@gmail.com', 'id': 'Doll-David-Andrew', 'name': {'family': 'Doll', 'given': 'David Andrew'}, 'show_email': 'NO'}]}
Year: 2011
DOI: 10.7907/E6S9-4D28
We present the results of a measurement of the total rate and photon energy spectrum in b -> sγ transitions using the entire BABAR data set, 429 fb<sup>-1</sup>. These results use a "sum of exclusives" approach in which we reconstruct a subset of the final states of the s-quark system and correct for the final states that are missing. We find B(B<sup>-</sup> -> X<sub>s</sub>γ)=(329 ± 19 ± 48)x10<sup>-6</sup> for Eγ>1.9 GeV. We also measure the mean and variance of the photon spectrum and find <E>=2.346 ± 0.018<sup>+0.027</sup><sub>-0.022</sub> and <E<sup>2</sup>> - <E><sup>2</sup> = 0.0211 ± 0.0057<sup>+0.0055</sup><sub>-0.0069</sub>. Finally we fit two classes of models for the photon spectrum and extract their respective HQET parameters.https://thesis.library.caltech.edu/id/eprint/6484Search for Gravitational Waves from a Nearby Neutron Star Using Barycentric Resampling
https://resolver.caltech.edu/CaltechTHESIS:09142010-170958877
Authors: {'items': [{'email': 'ppatel23@gmail.com', 'id': 'Patel-Pinkesh-Kiritbhai', 'name': {'family': 'Patel', 'given': 'Pinkesh Kiritbhai'}, 'show_email': 'YES'}]}
Year: 2011
DOI: 10.7907/00AG-ZF69
Rapidly spinning neutron stars in our Galactic neighborhood are promising sources of quasi-monochromatic continuous gravitational waves observable by the current LIGO detectors. I describe a search done on the LIGO S5 data, looking for an isolated neutron star hypothesized to be at a distance of about 100 parsecs. This kind of search is computationally bound and is made possible by the implementation of barycentric resampling, which is described here as well. I also describe the work done at the Hanford LIGO site, while taking data for the Astrowatch program.https://thesis.library.caltech.edu/id/eprint/6030A Search for Low-Mass Dark Matter with the Cryogenic Dark Matter Search and the Development of Highly Multiplexed Phonon-Mediated Particle Detectors
https://resolver.caltech.edu/CaltechTHESIS:05172012-142723949
Authors: {'items': [{'email': 'dcmoore@gmail.com', 'id': 'Moore-David-Craig', 'name': {'family': 'Moore', 'given': 'David Craig'}, 'show_email': 'NO'}]}
Year: 2012
DOI: 10.7907/X8JD-4R90
<p>A wide variety of astrophysical observations indicate that approximately 85% of the matter in the universe is nonbaryonic and nonluminous. Understanding the nature of this "dark matter" is one of the most important outstanding questions in cosmology. Weakly Interacting Massive Particles (WIMPs) are a leading candidate for dark matter since they would be thermally produced in the early universe in the correct abundance to account for the observed relic density of dark matter. If WIMPs account for the dark matter, then rare interactions from relic WIMPs should be observable in terrestrial detectors. Recently, unexplained excess events in the DAMA/LIBRA, CoGeNT, and CRESST-II experiments have been interpreted as evidence of scattering from WIMPs with masses ~10 GeV and spin-independent scattering cross sections of 10<sup>-41</sup>-10<sup>-40</sup> cm<sup>2</sup>.</p>
<p>The Cryogenic Dark Matter Search (CDMS II) attempts to identify WIMP interactions using an array of cryogenic germanium and silicon particle detectors located at the Soudan Underground Laboratory in northern Minnesota. In this dissertation, data taken by CDMS II are reanalyzed using a 2 keV recoil energy threshold to increase the sensitivity to WIMPs with masses ~10 GeV. These data disfavor an explanation for the DAMA/LIBRA, CoGeNT, and CRESST-II results in terms of spin-independent elastic scattering of WIMPs with masses ≲12 GeV, under standard assumptions. At the time of publication, they provided the strongest constraints on spin-independent elastic scattering from 5-9 GeV, ruling out previously unexplored parameter space.</p>
<p>To detect WIMPs or exclude the remaining parameter space favored by the most popular models will ultimately require detectors with target masses ≳1 ton, requiring an increase in mass by more than two orders of magnitude over CDMS II. For cryogenic detectors such as CDMS, scaling to such large target masses will require individual detector elements to be fabricated more quickly and cheaply, while maintaining the nearly background-free operation of the existing experiment. We describe the development of athermal phonon mediated particle detectors using Microwave Kinetic Inductance Detectors (MKIDs), which could provide a simpler path to extending the CDMS detector technology to the ton scale. Results from prototype devices have demonstrated energy resolutions as good as σ = 0.55 keV at 30 keV, comparable to existing CDMS II detectors. Such designs can be scaled to kg-scale detector elements, while reducing the complexity of the detector fabrication and cryogenic readout electronics relative to existing designs. Since MKIDs are naturally multiplexed in the frequency domain, MKID-based designs also allow much finer pixelization of the phonon sensor, which is expected to enhance background rejection for large detectors while simultaneously reducing the number of wires needed to read out the detectors.</p>https://thesis.library.caltech.edu/id/eprint/7043Measurement of the Direct CP Asymmetry in b→sγ via Sum of Exclusive B Meson Decays Using the BABAR Detector
https://resolver.caltech.edu/CaltechTHESIS:05022013-152247133
Authors: {'items': [{'email': 'piti118@gmail.com', 'id': 'Ongmongkolkul-Piti', 'name': {'family': 'Ongmongkolkul', 'given': 'Piti'}, 'show_email': 'NO'}]}
Year: 2013
DOI: 10.7907/ZNVN-R508
We perform a measurement of direct CP violation in b to sγ A<sub>CP</sub>, and the measurement of a difference between Acp for neutral B and charged B mesons, Delta A_{X_s\gamma}, using 429 inverse femtobarn of data recorded at the Upsilon(4S) resonance with the BABAR detector. B mesons are reconstructed from 16 exclusive final states. Particle identification is done using an algorithm based on Error Correcting Output Code with an exhaustive matrix. Background rejection and best candidate selection are done using two decision tree-based classifiers. We found $\acp = 1.73%+-1.93%+-1.02% and Delta A_X_sγ = 4.97%+-3.90%+-1.45% where the uncertainties are statistical and systematic respectively. Based on the measured value of Delta A_X_sgamma, we determine a 90% confidence interval for Im C_8g/C_7gamma, where C_7gamma and C_8g are Wilson coefficients for New Physics amplitudes, at -1.64 < Im C_8g/C_7gamma < 6.52.https://thesis.library.caltech.edu/id/eprint/7655Measuring R(D(*)) for B → ‾D(*)τν_τ using Semileptonic Tags and Tau Decays to Hadrons
https://resolver.caltech.edu/CaltechTHESIS:04092018-211419944
Authors: {'items': [{'email': 'dchao34@gmail.com', 'id': 'Chao-Daniel-Shuteh', 'name': {'family': 'Chao', 'given': 'Daniel Shuteh'}, 'show_email': 'NO'}]}
Year: 2018
DOI: 10.7907/25e6-j889
<p>We perform a measurement of R(D<sup>(*)</sup>) for B → <span style="text-decoration: overline">D</span>(*)τν<sub>τ</sub> using semileptonic tagging and τ decays to hadrons on the 429 fb<sup>-1</sup> of data that BABAR collected at the Υ(4S) resonance. This is the first measurement of R(D<sup>(*)</sup>) using the specied reconstruction channels. Candidate selection was performed with supervised learning, where the training labels were obtained by solving an instance of subgraph isomorphism. The signal extraction was performed by solving an optimization problem whose objective function required the evaluation of kernel density estimates that were accelerated by a branch-and-bound algorithm as well as with a GPU. The training data for the density estimates were themselves the output of two classier scores. We present a 68% and 95% confidence regions of R(D<sup>(*)</sup>), which do not show enough evidence to reject the standard model prediction.</p>https://thesis.library.caltech.edu/id/eprint/10797Measurement of R(D) and R(D*) Using Semileptonic Tags and Hadronic τ Decays
https://resolver.caltech.edu/CaltechTHESIS:01252019-144433241
Authors: {'items': [{'email': 'jaehongkim86@gmail.com', 'id': 'Kim-Jae-Hong', 'name': {'family': 'Kim', 'given': 'Jae Hong'}, 'orcid': '0000-0003-1968-2753', 'show_email': 'NO'}]}
Year: 2019
DOI: 10.7907/KF89-DS18
<p>We present a measurement of R(D<sup>(*)</sup>) = B(B → D̅<sup>(*)</sup> τν<sub>τ</sub>)/B(B → D̅<sup>(*)</sup> ℓν<sub>ℓ</sub>) using semileptonic tagging and hadronic τ decays on the 433 fb<sup>-1</sup> of data collected at the Υ(4S) resonance using the BaBar detector at the PEP-II collider. We obtain a high statistics data sample using loose selection criteria. The signal is extracted by performing a 2-dimensional fit of the component densities to the kernel density estimate of the data, which is made computationally tractable by algorithmic improvements and speedups provided by graphics processing units. We obtain two distinct central values based on the model used to represent the BB̅ background densities: R(D) = 0.231 ± 0.028 ± 0.028 and R(D<sup>*</sup>) = 0.127 ± 0.019 ± 0.031 with a correlation of 0.06 and R(D) = 1.454 ± 0.028 ± 0.028 and R(D<sup>*</sup>) = 1.507 ± 0.019 ± 0.031 with a correlation of 0.06. The region encompassed by the two results are consistent with both the Standard Model prediction and the world average.</p>https://thesis.library.caltech.edu/id/eprint/11364Search for Beyond Standard Model Physics at BaBar
https://resolver.caltech.edu/CaltechTHESIS:05232022-144829107
Authors: {'items': [{'email': 'yxli528@gmail.com', 'id': 'Li-Yunxuan', 'name': {'family': 'Li', 'given': 'Yunxuan'}, 'orcid': '0000-0001-9004-2471', 'show_email': 'YES'}]}
Year: 2022
DOI: 10.7907/tz7n-d662
<p>This thesis reports searches for beyond Standard Model physics in <span class="math inline"><em>e</em><sup>+</sup><em>e</em><sup>−</sup></span> collisions in two directions.</p>
<p>We report the first search for a dark matter bound state. The existence of dark matter bound states could arise in a simple dark sector model in which a dark photon (<span class="math inline"><em>A</em>′</span>) is light enough to generate an attractive force between dark fermions. We report herein a search for a <span class="math inline"><em>J</em><sup><em>P</em><em>C</em></sup> = 1<sup> − −</sup></span> darkonium state, the <span class="math inline"><em>Υ</em><sub><em>D</em></sub></span>, produced in the reaction <span class="math inline"><em>e</em><sup>+</sup><em>e</em><sup>−</sup> → <em>γ</em><em>Υ</em><sub><em>D</em></sub>, <em>Υ</em><sub><em>D</em></sub> → <em>A</em>′<em>A</em>′<em>A</em>′</span>, where the dark photons subsequently decay into pairs of leptons or pions, using data collected with the BaBar detector. No significant signal is observed, and we derive limits on the <span class="math inline"><em>γ</em> − <em>A</em>′</span> kinetic mixing (<span class="math inline"><em>ϵ</em></span>) as a function of the dark sector coupling constant for <span class="math inline">0.001 < <em>m</em><sub><em>A</em>′</sub> < 3.16</span> GeV and <span class="math inline">0.05 < <em>m</em><sub><em>Υ</em><sub><em>D</em></sub></sub> < 9.5</span> GeV. Bounds on the mixing strength <span class="math inline"><em>ϵ</em></span> down to <span class="math inline">5 × 10<sup> − 5</sup> − 10<sup> − 3</sup></span> are set for a large fraction of the parameter space.</p>
<p>We also report a measurement of <span class="math inline"><em>R</em>(<em>D</em>) = <em>B</em>(<em>B</em> → <em>D̄</em><em>τ</em><em>ν̄</em><sub><em>τ</em></sub>)/<em>B</em>(<em>B</em> → <em>D̄</em>ℓ<em>ν̄</em><sub>ℓ</sub>)</span> and <span class="math inline"><em>R</em>(<em>D</em><sup>*</sup>) = <em>B</em>(<em>B</em> → <em>D̄</em><sup>*</sup><em>τ</em><em>ν̄</em><sub><em>τ</em></sub>)/<em>B</em>(<em>B</em> → <em>D̄</em><sup>*</sup>ℓ<em>ν̄</em><sub>ℓ</sub>)</span>, where <span class="math inline">ℓ</span> refers to either an electron or muon. We select samples by reconstructing tag-side <span class="math inline"><em>B</em></span> mesons in semileptonic decays and signal-side <span class="math inline"><em>τ</em></span> in a purely leptonic decay. Using data collected with the BaBar detector, we measure <span class="math inline"><em>R</em>(<em>D</em>) = 0.316 ± 0.062(stat) ± 0.019(syst)</span> and <span class="math inline"><em>R</em>(<em>D</em><sup>*</sup>) = 0.226 ± 0.022(stat) ± 0.012(syst)</span>, which agree with the Standard Model expectations by <span class="math inline">0.26<em>σ</em></span> and <span class="math inline">1.10<em>σ</em></span>, respectively. Taken together, the results are in agreement with the Standard Model within <span class="math inline">1.51<em>σ</em></span> level.</p>https://thesis.library.caltech.edu/id/eprint/14598SuperCDMS SNOLAB, HVeV Run 3, and Development of KIPM Detectors
https://resolver.caltech.edu/CaltechTHESIS:11272023-225643701
Authors: {'items': [{'email': 'tbaralis@gmail.com', 'id': 'Aralis-Taylor-Benjamin', 'name': {'family': 'Aralis', 'given': 'Taylor Benjamin'}, 'orcid': '0000-0002-3501-6948', 'show_email': 'NO'}]}
Year: 2024
DOI: 10.7907/gxjp-0863
<p>Dark matter is the theorized source of many observed large-scale gravitational effects. It is dark in the sense that it lacks any heretofore measurable direct interaction with the electromagnetic spectrum. Being unable to rely on absorption, reflection, or emission of photons makes studying dark matter particularly challenging. Excluding neutrinos, which fail to explain the observed large-scale effects, dark matter has never been conclusively identified in a local laboratory experiment. There are many proposed models that could explain both our large-scale observations and our lack of local observations while still allowing for the possibility of local observation. Ultra-sensitive direct-detection experiments attempt to make precisely such observations. Confirmed detection of a new stable particle would provide important information for improving our understanding of both dark matter and cosmological models.</p>
<p>The SuperCDMS SNOLAB experiment is a direct-detection experiment designed with an initial focus on particle masses < 10 GeV. The experiment will measure both phonon and ionization signals in kg-scale semiconductor crystals held at cryogenic temperatures. In this thesis, I describe the experiment with emphasis on the ionization readout. I also detail the characterization process I performed on the ionization amplifier's low-power high-electron-mobility transistors (HEMTs).</p>
<p>SuperCDMS high-voltage eV-resolution (HVeV) detectors are gram-scale detectors designed to achieve single electron-hole-pair sensitivity. The first HVeV direct-detection search produced world-leading exclusion limits for dark-matter masses down to ~1 MeV. Here, I present my work analyzing the third search using such detectors. Run 3 was the first to include multiple detectors operated simultaneously and achieved an order of magnitude greater exposure than previous runs. I report the resulting exclusion limits for electron-coupled, dark-photon, and axion-like-particle dark matter.</p>
<p>Lastly, I discuss work performed at Caltech towards the development of kinetic-inductance phonon-mediated (KIPM) dark-matter detectors. KIPM detectors use frequency-multiplexed kinetic inductance detectors (KIDs) and have the potential for excellent event-position reconstruction and background rejection. KIPMs also present a clear path towards sub-eV resolution on event recoil energy. Such detectors could be used as part of a payload upgrade in SuperCDMS SNOLAB. KIPMs could also be used in smaller-scale experiments similar to SuperCDMS HVeV.</p>https://thesis.library.caltech.edu/id/eprint/16252