384 research outputs found
Finite temperature QCD in the quark-composites approach
We investigate QCD at finite temperature in the quark composites approach,
which is based on the use of quark composites with hadronic quantum numbers as
fundamental variables. We find that chiral symmetry restoration and quark
deconfinement are one and the same first order phase transition, whose critical
temperature, in a one loop approximation, is , where is the pion mass, the number of
up and down quark components, and a parameter of order 1 whose precise
value can be determined by the study of the pion-pion interaction.Comment: LaTex, 5 page
Chiral symmetry breaking and quark confinement in the nilpotency expansion of QCD
We apply to lattice QCD a bosonization method previously developed in which
dynamical bosons are generated by time-dependent Bogoliubov transformations.
The transformed action can be studied by an expansion in the inverse of the
nilpotency index, which is the number of fermionic states in the structure
function of composite bosons. When this number diverges the model is solved by
the saddle point method which has a variational interpretation. We give a
stationary covariant solution for a background matter field whose fluctuations
describe mesons. In the saddle point approximations live fermionic
quasiparticles with quark quantum numbers which are confined, in the sense that
they propagate only in pointlike color singlets. Conditions for chiral symmetry
breaking are determined, to be studied numerically, and a derivation of
mesons-nucleons action is outlined.Comment: 33 page
Transfer matrix for Kogut-Susskind fermions in the spin basis
In the absence of interaction it is well known that the Kogut-Susskind
regularizations of fermions in the spin and flavor basis are equivalent to each
other. In this paper we clarify the difference between the two formulations in
the presence of interaction with gauge fields. We then derive an explicit
expression of the transfer matrix in the spin basis by a unitary transformation
on that one in the flavor basis which is known. The essential key ingredient is
the explicit construction of the fermion Fock space for variables which live on
blocks. Therefore the transfer matrix generates time translations of two
lattice units.Comment: 16 page
Absence of sign problem in the (saddle point approximation of the) nilpotency expansion of QCD at finite chemical potential
We have developed a method to derive the (approximate) quark contribution to
the fermion free energy of QCD on a lattice, at finite temperature and chemical
potential, with Kogut-Susskind fermions in the flavor basis. We show here the
expression at zero temperature. This result has been obtained at the lowest
order of the nilpotency expansion. At this order the well known "sign problem"
does not arise and the quark contribution to the action can be used as a
statistical weight in the Monte Carlo simulations.Comment: 7 pages, presented at the XXVIII International Symposium on Lattice
Field Theory (Lattice 2010), Villasimius, Sardinia, Italy, June 14-19, 201
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