Phd records
https://feeds.library.caltech.edu/people/Lee-C-L-Y/Phd.rss
A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenWed, 31 Jan 2024 19:20:06 +0000Quantum effective field theories in heavy quark physics and phase transitions in cosmology
https://resolver.caltech.edu/CaltechTHESIS:04182012-104107815
Authors: {'items': [{'id': 'Lee-C-L-Y', 'name': {'family': 'Lee', 'given': 'Clarence L. Y.'}, 'show_email': 'NO'}]}
Year: 1994
DOI: 10.7907/tr7n-vw39
<p>This thesis is concerned with aspects of quantum effective field theories, effective
actions, and their applications. New spin-flavor symmetries of the strong interactions,
which arise in the limit of very large quark masses, can be incorporated into a heavy
quark effective field theory (HQEFT). A general method for deriving the effective
Lagrangian of this theory to any order in 1/m_Q (where m_Q is the heavy quark mass)
is developed; it is used to calculate terms up to order 1/m^3_Q. The renormalization of
terms in the Lagrangian to order 1/m^2_Q is performed. Such operators break these new
symmetries and consequently are important corrections to the leading-order predictions.
HQEFT can be combined with chiral perturbation theory into a heavy meson
chiral perturbation theory (HMChPT) which describes the low-momentum interactions
of hadrons containing a heavy quark with pseudo-Goldstone bosons. HMChPT
is used to investigate the semi-leptonic four-body decay of B and D mesons into final
states with at least one Goldstone boson. Such processes may be utilized to test
the above heavy quark symmetries. The remainder of this dissertation deals with the
evaluation of effective actions and their implications. A method to efficiently compute
the one-loop effective action at zero and finite temperatures is elucidated. In a first
order cosmological phase transition, the decay rate and the temperature at which it
occurs depends on the free energy of a critical bubble configuration. Since this free
energy is related to the effective action but is usually approximated with an effective
potential, the calculational method developed above is used to study the validity of
of this approximation. The corrections are found to be important for quantitative
work.</p>
https://thesis.library.caltech.edu/id/eprint/6943