We have carried out numerical studies of vacuum alignment in technicolor models of electroweak and flavor symmetry breaking. The goal is to understand alignment implications for strong and weak CP ...nonconservation in quark interactions. In this first part, we restrict our attention to the technifermion sector of simple models. We find several interesting phenomena, including (1) the possibility that all observable phases in the technifermions' unitary vacuum-alignment matrix are integer multiples of {pi}/N{sup '} where N{sup '}{<=}N, the number of technifermion doublets, and (2) the possibility of exceptionally light pseudo Goldstone technipions. (c) 2000 The American Physical Society.
Virtual quark pair screening leads to breaking of the string between fundamental representation quarks in QCD. For unquenched four dimensional lattice QCD, this (so far elusive) phenomenon is studied ...using the recently developed truncated determinant algorithm (TDA). The dynamical configurations were generated on a 650 MHz PC. Quark eigenmodes up to 420 MeV are included exactly in these TDA studies performed at low quark mass on large coarse but O(a{sup 2}) improved lattices. A study of Wilson line correlators in Coulomb gauge extracted from an ensemble of 1000 two-flavor dynamical configurations reveals evidence for flattening of the string tension at distances R{approx}>1 fm.
Hadronic decays of excited heavy mesons Di Pierro, M.; Eichten, E.
Nuclear physics. Section B, Proceedings supplement,
03/2001, Volume:
93, Issue:
1
Journal Article
Open access
We studied the hadronic decays of excited states of heavy mesons (
D,
D
s
,
B and
B
s
) to lighter states by emission of π, η or
K. Wavefunctions and energy levels of these excited states are ...determined using a Dirac equation for the light quark in the potential generated by the heavy quark (including first order corrections in the heavy quark expansion). Transition amplitudes are computed in the context of the Heavy Chiral Quark Model.
A method for computing all-point quark propagators is applied to a variety of processes of physical interest in lattice QCD. The method allows, for example, efficient calculation of disconnected ...parts and full momentum-space 2 and 3 point functions. Examples discussed include: extraction of chiral Lagrangian parameters from current correlators, the pion form factor, and the unquenched eta-prime.
We present results of a high-statistics study of scalar and pseudoscalar meson propagators in quenched QCD at two values of lattice spacing,β = 5.7 and 5.9, with clover-improved Wilson fermions. The ...study of the chiral limit is facilitated by the pole-shifting ansatz of the modified quenched approximation. Pseudoscalar masses and decay constants are determined as a function of quark mass and quenched chiral log effects are estimated. A study of the flavor singlet ν′ hairpin diagram yields a precise determination of the ν′ mass insertion. The corresponding value of the quenched chiral log parameter b is compared with the observed QCL effects. Removal of QCL effects from the scalar propagator allows a determination of the mass of the lowest lying isovector scalar
qq meson.
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