71 research outputs found
Vector Meson Masses in Chiral Perturbation Theory
We discuss the vector meson masses within the context of Chiral Perturbation
Theory performing an expansion in terms of the momenta, quark masses and 1/Nc.
We extend the previous analysis to include isospin breaking effects and also
include up to order . We discuss vector meson chiral perturbation theory
in some detail and present a derivation from a relativistic lagrangian. The
unknown coefficients are estimated in various ways. We also discuss the
relevance of electromagnetic corrections and the implications of the present
calculation for the determination of quark masses.Comment: 17 pages, LaTeX, 2 figures. Revised version to appear in Nuclear
Physics B. One reference added, some misprints, mainly in the appendix,
correcte
Matching the Heavy Vector Meson Theory
We show how to obtain a ``heavy'' meson effective lagrangian for the case
where the number of heavy particles is not conserved. We apply the method in a
simple example at tree level and perform then the reduction for the case of
vector mesons in Chiral Perturbation Theory in a manifestly chiral invariant
fashion. Some examples showing that ``heavy'' meson effective theory also works
at the one-loop level are included.Comment: 11 pages, 2 figures, revte
Regularized Casimir energy for an infinite dielectric cylinder subject to light-velocity conservation
The Casimir energy of a dilute dielectric cylinder, with the same
light-velocity as in its surrounding medium, is evaluated exactly to first
order in and numerically to higher orders in . The first part is
carried out using addition formulas for Bessel functions, and no Debye
expansions are required
Charm Quark Mass Dependence of QCD Corrections to Nonleptonic Inclusive B Decays
We calculate the radiative corrections to the nonleptonic inclusive B decay
mode taking into account the charm quark mass.
Compared to the massless case, corrections resulting from a nonvanishing c
quark mass increase the nonleptonic rate by (4--8)\%, depending on the
renormalization point. As a by--product of our calculation, we obtain an
analytic expression for the radiative correction to the semileptonic decay
taking into account the lepton mass, and
estimate the c quark mass effects on the nonleptonic decay mode .Comment: 38 pages, TUM-T31-67/94/R (to be published in Nuclear Physics) (one
reference added and used for an improved phenomenological analysis
Galilean Lee Model of the Delta Function Potential
The scattering cross section associated with a two dimensional delta function
has recently been the object of considerable study. It is shown here that this
problem can be put into a field theoretical framework by the construction of an
appropriate Galilean covariant theory. The Lee model with a standard Yukawa
interaction is shown to provide such a realization. The usual results for delta
function scattering are then obtained in the case that a stable particle exists
in the scattering channel provided that a certain limit is taken in the
relevant parameter space. In the more general case in which no such limit is
taken finite corrections to the cross section are obtained which (unlike the
pure delta function case) depend on the coupling constant of the model.Comment: 7 pages, latex, no figure
Cooper pair dispersion relation in two dimensions
The Cooper pair binding energy {\it vs.} center-of-mass-momentum dispersion
relation for Bose-Einstein condensation studies of superconductivity is found
in two dimensions for a renormalized attractive delta interaction. It crosses
over smoothly from a linear to a quadratic form as coupling varies from weak to
strong.Comment: 2 pages, 1 figure, new version published in Physica
The Isgur-Wise Function to from Sum Rules in the Heavy Quark Effective Theory
Radiative corrections to both perturbative and non-perturbative contributions
are added to existing calculations of the Isgur-Wise function . To
this end, we develop a method for calculating two-loop integrals in the heavy
quark effective theory involving two different scales. The inclusion of
terms causes to decrease as compared to the lowest
order result and shows the importance of quantum effects. The slope parameter
violates the bound given by de Rafael and Taron.Comment: 11 pages, 2 figures (not included), (LaTeX), HD-THEP-92-4
Renormalizabilty of TH Heavy Quark Effective Theory
We show that the Heavy Quark Effective Theory is renormalizable
perturbatively. We also show that there exist renormalization schemes in which
the infinite quark mass limit of any QCD Green function is exactly given by the
corresponding Green function of the Heavy Quark Effective Theory. All this is
accomplished while preserving BRS invariance.Comment: LATEX/10 pages/ UAB-FT-314/ (References have been added.) figures
(PS) available on request. Unfortunately some mails asking for copies by
conventional mail were lost. Please resend request
Non-perturbative regularization and renormalization: simple examples from non-relativistic quantum mechanics
We examine several zero-range potentials in non-relativistic quantum
mechanics. The study of such potentials requires regularization and
renormalization. We contrast physical results obtained using dimensional
regularization and cutoff schemes and show explicitly that in certain cases
dimensional regularization fails to reproduce the results obtained using cutoff
regularization. First we consider a delta-function potential in arbitrary space
dimensions. Using cutoff regularization we show that for the
renormalized scattering amplitude is trivial. In contrast, dimensional
regularization can yield a nontrivial scattering amplitude for odd dimensions
greater than or equal to five. We also consider a potential consisting of a
delta function plus the derivative-squared of a delta function in three
dimensions. We show that the renormalized scattering amplitudes obtained using
the two regularization schemes are different. Moreover we find that in the
cutoff-regulated calculation the effective range is necessarily negative in the
limit that the cutoff is taken to infinity. In contrast, in dimensional
regularization the effective range is unconstrained. We discuss how these
discrepancies arise from the dimensional regularization prescription that all
power-law divergences vanish. We argue that these results demonstrate that
dimensional regularization can fail in a non-perturbative setting.Comment: 19 pages, LaTeX, uses epsf.te
- …