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A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenSat, 13 Apr 2024 01:53:43 +0000Some Topics in Theoretical High-Energy Physics
https://resolver.caltech.edu/CaltechETD:etd-06142007-142536
Authors: {'items': [{'id': 'Wolfram-Stephen', 'name': {'family': 'Wolfram', 'given': 'Stephen'}, 'show_email': 'NO'}]}
Year: 1980
DOI: 10.7907/S6JE-QF83
This thesis discusses various aspects of theoretical high-energy physics. The first two sections describe methods for investigating QCD effects in e⁺e⁻ annihilation to hadrons. The third section presents some predictions for various features of QCD jets. The fourth section shows that any fermions in the standard weak interaction model must have masses ≾100 GeV. In the fifth section, the abundances of any new absolutely stable heavy particles which should have been produced in the early universe are estimated, and found to be inconsistent with observational limits. Finally, the sixth section describes the development of a baryon excess in the very early universe due to B, CP violating interactions.
https://thesis.library.caltech.edu/id/eprint/2597Measurements of νN Charged Current Cross Sections from E_ν = 25 GEV to E_ν = 260 GEV
https://resolver.caltech.edu/CaltechTHESIS:05082018-150004002
Authors: {'items': [{'id': 'Lee-James-Roy', 'name': {'family': 'Lee', 'given': 'James Roy'}, 'show_email': 'NO'}]}
Year: 1981
DOI: 10.7907/5mvb-k724
<p>The primary objective of this experiment was to measure normalized cross sections for the interaction νN → μ<sup>-</sup>X at energies up to E<sub>ν</sub> = 260 GEV.</p>
<p>The Fermilab dichromatic neutrino beam is made by focusing 400 GEV protons onto a BeO target to produce a secondary beam containing pions and kaons. Pions and kaons decay into neutrinos in a 340m evacuated decay pipe. The absolute π and K flux was determined by measuring the total flux of secondary particles with an ionization chamber and by measuring relative particle composition with a Cherenkov counter. The decay of pions and kaons into neutrinos was calculated to obtain the normalized ν flux at the detector.</p>
<p>We observed 6500 charged current interactions in an 1100 ton iron ν target. Hadron energy deposited in the detector was measured with calorimetric techniques. Muon trajectories were measured with spark chambers. Muon momenta were measured with an iron toroidal magnet.</p>
<p>The total charged current cross section was measured to be σ/E<sub>ν</sub> = (.700 ±. 038) x 10<sup>-38</sup> cm<sup>2</sup>/GEV independent of energy from E<sub>ν</sub> = 25 GEV to E<sub>ν</sub> = 260 GEV. This sets a lower bound on the mass of the W boson of M<sub>W</sub> > 27 GEV at the 90% confidence level. The mean inelasticity is < y > = .484 ± .012 independent of energy. The antiquark fraction of the nucleon is α = .21 ± .07 at a mean neutrino energy of E<sub>ν</sub> = 226 GEV. The x distributions were measured in the region .1 < y < .4 at E<sub>ν</sub> = 67 GEV and at E<sub>ν</sub> = 226 GEV. Scaling violations were found at low x, but they can be removed by using the scaling variable x' = x/(1 + M<sup>2</sup><sub>N</sub>/Q<sup>2</sup>).</p>
<p>These results are in good agreement with a simple quark-parton model of deep inelastic scattering.</p>https://thesis.library.caltech.edu/id/eprint/10864A Total Cross Section and Y Distribution Measurement for Muon Type Neutrinos and Antineutrinos on Iron
https://resolver.caltech.edu/CaltechTHESIS:10162009-153203198
Authors: {'items': [{'id': 'Blair-Robert-Eugene', 'name': {'family': 'Blair', 'given': 'Robert Eugene'}, 'show_email': 'NO'}]}
Year: 1982
DOI: 10.7907/t0ve-vp84
<p>The measurement of the total charged current cross section for neutrinos and antineutrinos on iron is described. The data consist of 55,000 neutrino and 17,000 antinuetrino events taken in the N30 Dichromatic train at Fermi National Laboratory. The events cover the energy range 30-230 GeV. The slope of the cross section is consistent with flat over this energy range but favors a rise with energy. The results of fits to the y distribution of the form β((1-α)+α(1-γ)<sup>2</sup> - Rγ<sup>2</sup>/2(1+R) for neutrinos and β((1-α)(1-γ)<sup>2</sup> + α - Rγ<sup>2</sup>/2(1+R) for antineutrinos (with R = 1) are reported. A comparison is made between the measured cross sections and the level of <i>e d</i> and <i>µ</i>Fe scattering cross sections. The effect of a W propagator, QCD and neutrino oscillations on the cross section is described. The level of effects allowed by the data for oscillations and a propagator are estimated.</p>
https://thesis.library.caltech.edu/id/eprint/5303Nucleon Structure from Neutrino Interactions in an Iron Target with a Study of the Singlet Quark Distribution
https://resolver.caltech.edu/CaltechTHESIS:11272018-121922950
Authors: {'items': [{'id': 'MacFarlane-David-Brian', 'name': {'family': 'MacFarlane', 'given': 'David Brian'}, 'show_email': 'NO'}]}
Year: 1984
DOI: 10.7907/93ev-4g25
<p>Nucleon structure functions have been extracted from a large sample of neutrino and anti-neutrino inclusive charged-current events. These data were obtained over the period from June, 1979 through January, 1980, using the Lab E detector in the N30 dichromatic beam at Fermilab (experiment E616).</p>
<p>The use of the narrow-band beam made possible flux normalized cross section and structure function measurements. Neutrinos were obtained from sign and momentum selected pions and kaons produced from 400GeV primary protons. Details of the methods used to monitor and determine properties of the secondary beam are provided. The flux of neutrinos at the detector was calculated from this knowledge.</p>
<p>The Lab E detector performed the function of neutrino target, as well as measuring final state properties of the events. Hadron energy was measured using calorimetry. Spark chambers interspersed throughout the target and following toroidal spectrometer were used to sample the position of the outgoing muon. From these measurements, the muon angle and momentum could be determined. The procedure used for reconstructing physics variables from detector measurements is presented with estimates of systematic errors.</p>
<p>The methods used to extract structure functions from the data are detailed. An analysis of sources of systematic error on these results is made. A comparison of our results for F<sub>2</sub> is made with other measurements from both neutrino and charged lepton scattering. Differences in overall normalization and in the x dependence of the structure function are found. The mean square quark charge rule from the quark-parton model is confirmed at the 10% level. Quantum Chromodynamics (QCD) predicts a pattern of scaling violations in F<sub>2</sub> which is observed in our results. This has been quantified by making fits to the data using numerical integration of the Altarelli-Parisi equations. The value of Λ<sub>MS</sub>, the QCD scale parameter, is found to be 340±100±60MeV with an additional uncertainty of ±50MeV due to the unknown form of the gluon distribution.</p>
https://thesis.library.caltech.edu/id/eprint/11286Nucleon 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/7585