6,788 research outputs found

### Diquarks in the color--flavor locked phase of dense quark matter

Diquark excitations of dense quark matter are considered in the framework of
the Nambu -- Jona-Lasinio model with three types of massless quarks in the
presense of a quark number chemical potential $\mu$. We investigate the
effective action of meson- and diquark fields at sufficiently high values of
$\mu$, where the color--flavor locked (CFL) phase is realized, and prove the
existence of NG-bosons in the sector of pseudoscalar diquarks. In the sector of
scalar diquarks an additional NG-boson is found, corresponding to the
spontaneous breaking of the U(1)$_B$ baryon symmetry in the CFL phase. Finally,
the existence of massive scalar and pseudoscalar diquark excitations is
demonstrated.Comment: 10 pages, 2 figures; version accepted for publication in PR

### An alternative construction of B-M and B-T unitals in Desarguesian planes

We present a new construction of non-classical unitals from a classical
unital $U$ in $PG(2,q^2)$. The resulting non-classical unitals are B-M unitals.
The idea is to find a non-standard model $\Pi$ of $PG(2,q^2)$ with the
following three properties: 1. points of $\Pi$ are those of $PG(2,q^2)$; 2.
lines of $\Pi$ are certain lines and conics of $PG(2,q^2)$; 3. the points in
$U$ form a non-classical B-M unital in $\Pi$.
Our construction also works for the B-T unital, provided that conics are
replaced by certain algebraic curves of higher degree.Comment: Keywords: unital, desarguesian plane 11 pages; ISSN: 0012-365

### Gravitational catalysis of chiral and color symmetry breaking of quark matter in hyperbolic space

We study the dynamical breaking of chiral and color symmetries of dense quark
matter in the ultrastatic hyperbolic spacetime $R\otimes H^3$ in the framework
of an extended Nambu--Jona-Lasinio model. On the basis of analytical
expressions for chiral and color condensates as functions of curvature and
temperature, the phenomenon of dimensional reduction and gravitational
catalysis of symmetry breaking in strong gravitational field is demonstrated in
the regime of weak coupling constants. In the case of strong couplings it is
shown that curvature leads to small corrections to the flat-space values of
condensate and thus enhances the symmetry breaking effects. Finally, using
numerical calculations phase transitions under the influence of chemical
potential and negative curvature are considered and the phase portrait of the
system is constructed.Comment: 14 pages, 5 figure

### The Momentum--Space Bosonization of the Nambu--Jona-Lasinio Model with Vector and Axial-Vector Mesons

The momentum-space bosonization method is extended to the case of a
Nambu--Jona-Lasinio type model with vector and axial-vector mesons. The method
presented gives the possibility of deriving any meson vertex function to all
orders in momenta and to the leading order in $1/N_c$. Two-point functions,
which describe one-particle transitions to the hadronic vacuum, and meson
self-energies are considered. We find new relations which generalize the
well-known KSFR relation and both the first and the second Weinberg sum rules.
These result from a consistent treatment of higher order terms in the momentum
expansion.Comment: 11pp, TeX, CRN 93-5

### Bosonization in Particle Physics

Path integral techniques in collective fields are shown to be a useful
analytical tool to reformulate a field theory defined in terms of microscopic
quark (gluon) degrees of freedom as an effective theory of collective boson
(meson) fields. For illustrations, the path integral bosonization approach is
applied to derive a (non)linear sigma model from a Nambu-Jona-Lasinio (NJL)
quark model. The method can be extended to include higher order derivative
terms in meson fields or heavy-quark symmetries. It is also approximately
applicable to QCD.Comment: 12 pages, LaTeX, uses lamuphys.sty, 5 LaTeX figures, talk given at
the Workshop "Field Theoretical Tools in Polymer and Particle Physics",
University Wuppertal, June 17-19, 199

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