585 research outputs found
Enforced neutrality and color-flavor unlocking in the three-flavor Polyakov-loop NJL model
We study how the charge neutrality affects the phase structure of
three-flavor PNJL model. We point out that, within the conventional PNJL model
at finite density the color neutrality is missing because the Wilson line
serves as an external ``colored'' field coupled to dynamical quarks. In this
paper we heuristically assume that the model may still be applicable. To get
color neutrality one has then to allow non vanishing color chemical potentials.
We study how the quark matter phase diagram in -plane is
affected by imposing neutrality and by including the Polyakov loop dynamics.
Although these two effects are correlated in a nonlinear way, the impact of the
Polyakov loop turns out to be significant in the direction, while imposing
neutrality brings a remarkable effect in the direction. In
particular, we find a novel unlocking transition, when the temperature is
increased, even in the chiral SU(3) limit. We clarify how and why this is
possible once the dynamics of the colored Polyakov loop is taken into account.
Also we succeed in giving an analytic expression for for the transition
from two-flavor pairing (2SC) to unpaired quark matter in the presence of the
Polyakov loop.Comment: 11 pages, REVTex4, 10 eps figures; v2: added two notes, added a
reference; version to appear in Phys. Rev.
Superfluid and Pseudo-Goldstone Modes in Three Flavor Crystalline Color Superconductivity
We study the bosonic excitations in the favorite cubic three flavor
crystalline LOFF phases of QCD. We calculate in the Ginzburg-Landau
approximation the masses of the eight pseudo Nambu-Goldstone Bosons (NGB)
present in the low energy theory. We also compute the decay constants of the
massless NGB Goldstones associated to superfluidity as well as those of the
eight pseudo NGB. Differently from the corresponding situation in the
Color-Flavor-Locking phase, we find that meson condensation phases are not
expected in the present scenario.Comment: 10 pages, RevTeX4 class. Section IIIA enlarged, to appear on Phys.
Rev.
Meissner masses in the gCFL phase of QCD
We calculate the Meissner masses of gluons in neutral three-flavor color
superconducting matter for finite strange quark mass. In the CFL phase the
eissner masses are slowly varying function of the strange quark mass. For large
strange quark mass, in the so called gCFL phase, the Meissner masses of gluons
with colors and 8 become imaginary, indicating an instability.Comment: New Fig. 1 shows that also the masses of the gluons 3 and 8 are
imaginar
Effective Lagrangian for Heavy and Light Mesons: Semileptonic Decays
We introduce an effective lagrangian including negative and positive parity
heavy mesons containing a heavy quark, light pseudoscalars, and light vector
resonances, with their allowed interactions, using heavy quark spin-flavour
symmetry, chiral symmetry, and the hidden symmetry approach for light vector
resonances. On the basis of such a lagrangian, by considering the allowed weak
currents and by including the contributions from the nearest unitarity poles we
calculate the form factors for semileptonic decays of and mesons into
light pseudoscalars and light vector resonances. The available data, together
with some additional assumptions, allow for a set of predictions in the
different semileptonic channels, which can be compared with those following
{}from different approaches. A discussion of non-dominant terms in our
approach, which attempts at including a rather complete dynamics, will however
have to wait till more abundant data become available.Comment: LaTeX (style article), 19 pages, UGVA-DPT 1992/11-790, BARI-TH/92-12
The s-sbar and K-Kbar nature of f_0(980) in D_s decays
We examine the D_s -> f_0(980) pi amplitude through a constituent quark-meson
model, incorporating heavy quark and chiral symmetries, finding a good
agreement with the recent E791 data analysis of D_s -> 3pi via f_0(980). The
f_0(980) resonance is considered at the moment of production as an s sbar
state, later evolving to a superposition of mainly s sbar and K Kbar. The
analysis is also extended to the more frequent process D_s -> phi pi.Comment: 8 pages, 5 figure
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