159,452 research outputs found
Large Component QCD and Theoretical Framework of Heavy Quark Effective Field Theory
Based on a large component QCD derived directly from full QCD by integrating
over the small components of quark fields with , an
alternative quantization procedure is adopted to establish a basic theoretical
framework of heavy quark effective field theory (HQEFT) in the sense of
effective quantum field theory. The procedure concerns quantum generators of
Poincare group, Hilbert and Fock space, anticommutations and velocity
super-selection rule, propagator and Feynman rules, finite mass corrections,
trivialization of gluon couplings and renormalization of Wilson loop. The
Lorentz invariance and discrete symmetries in HQEFT are explicitly illustrated.
Some new symmetries in the infinite mass limit are discussed. Weak transition
matrix elements and masses of hadrons in HQEFT are well defined to display a
manifest spin-flavor symmetry and corrections. A simple trace
formulation approach is explicitly demonstrated by using LSZ reduction formula
in HQEFT, and shown to be very useful for parameterizing the transition form
factors via expansion. As the heavy quark and antiquark fields in HQEFT
are treated on the same footing in a fully symmetric way, the quark-antiquark
coupling terms naturally appear and play important roles for simplifying the
structure of transition matrix elements, and for understanding the concept of
`dressed heavy quark' - hadron duality. In the case that the `longitudinal' and
`transverse' residual momenta of heavy quark are at the same order of power
counting, HQEFT provides a consistent approach for systematically analyzing
heavy quark expansion in terms of . Some interesting features in
applications of HQEFT to heavy hadron systems are briefly outlined.Comment: 59 pages, RevTex, no figures, published versio
Exclusive B-meson Rare Decays and General Relations of Form Factors in Effective Field Theory of Heavy Quarks
B meson rare decays ( and ) are
analyzed in the framework of effective field theory of heavy quarks. The
semileptonic and penguin type form factors for these decays are calculated by
using the light cone sum rules method at the leading order of
expansion. Four exact relations between the two types of form factors are
obtained at the leading order of expansion. Of particular, the
relations are found to hold for whole momentum transfer region. We also
investigate the validity of the relations resulted from the large energy
effective theory based on the general relations obtained in the present
approach. The branching ratios of the rare decays are presented and their
potential importance for extracting the CKM matrix elements and probing new
physics is emphasized.Comment: 23 pages, Revtex, 32 figures, published version with the errors of
numerical results caused by the computer program are correcte
Transition Form Factors and Decay Rates with Extraction of the CKM parameters , ,
A systematic calculation for the transition form factors of heavy to light
mesons () is carried out
by using light-cone sum rules in the framework of heavy quark effective field
theory. The heavy quark symmetry at the leading order of expansion
enables us to reduce the independent wave functions and establish interesting
relations among form factors. Some relations hold for the whole region of
momentum transfer. The meson distribution amplitudes up to twist-4 including
the contributions from higher conformal spin partial waves and light meson mass
corrections are considered. The CKM matrix elements , and
are extracted from some relatively well-measured decay channels. A
detailed prediction for the branching ratios of heavy to light meson decays is
then presented. The resulting predictions for the semileptonic and radiative
decay rates of heavy to light mesons () are found to be compatible with the current experimental data
and can be tested by more precise experiments at B-factory, LHCb, BEPCII and
CLEOc.Comment: 23 pages, 32 figures, 25 tables,published version, minor corrections
and references adde
Constraints on asymmetry of the proton in chiral effective theory
We compute the asymmetry in the proton in chiral effective theory,
using phenomenological constraints based upon existing data. Unlike previous
meson cloud model calculations, which accounted for kaon loop contributions
with on-shell intermediate states alone, this work includes off-shell terms and
contact interactions, which impact the shape of the difference. We
identify a valence-like component of which is balanced by a
-function contribution to at , so that the integrals
of and over the experimentally accessible region are not
equal. Using a regularization procedure that preserves chiral symmetry and
Lorentz invariance, we find that existing data limit the integrated value of
the second moment of the asymmetry to the range at a scale of GeV. This is too small to account for the NuTeV anomaly and of the wrong
sign to enhance it.Comment: 5 pages, 4 figure
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