1,595 research outputs found
Thermodynamics of the PNJL model with nonzero baryon and isospin chemical potentials
We have extended the Polyakov-Nambu-Jona-Lasinio (PNJL) model for two
degenerate flavours to include the isospin chemical potential (). All
the diagonal and mixed derivatives of pressure with respect to the quark number
(proportional to baryon number) chemical potential () and isospin
chemical potential upto sixth order have been extracted at .
These derivatives give the generalized susceptibilities with respect to quark
and isospin numbers. Similar estimates for the flavour diagonal and
off-diagonal susceptibilities are also presented. Comparison to Lattice QCD
(LQCD) data of some of these susceptibilities for which LQCD data are
available, show similar temperature dependence, though there are some
quantitative deviations above the crossover temperature. We have also looked at
the effects of instanton induced flavour-mixing coming from the chiral
symmetry breaking 't Hooft determinant like term in the NJL part of the model.
The diagonal quark number and isospin susceptibilities are completely
unaffected. The off-diagonal susceptibilities show significant dependence near
the crossover. Finally we present the chemical potential dependence of specific
heat and speed of sound within the limits of chemical potentials where neither
diquarks nor pions can condense.Comment: 15 pages, 7 figures, Added discussions and references, version to
appear in Phys. Rev.
Susceptibilities and speed of sound from PNJL model
We present the Taylor expansion coefficients of the pressure in quark number
chemical potential , for the strongly interacting
matter as described by the PNJL model for two light degenerate flavours of
quarks u and d. The expansion has been done upto eighth order in , and
the results are consistent with recent estimates from Lattice. We have further
obtained the specific heat , squared speed of sound and the
conformal measure \cC.Comment: 13 pages, 8 figures, References added, some discussions on Fig. 4
modified, one table added, results unchanged, version to appear in Phys. Rev.
PNJL model with a Van der Monde term
We extend the Polyakov-Nambu-Jona-Lasinio (PNJL) model for two degenerate
flavours by including the effect of the SU(3) measure with a Van der Monde
(VdM) term. This ensures that the Polyakov loop always remains in the domain
[0,1]. The pressure, energy density, specific heat, speed of sound and
conformal measure show small or negligible effects from this term. However
various quark number and isospin susceptibilities are all found to approach
their respective ideal gas limits around 2 . We compare our methods with
other similar approaches in PNJL model and also present a quantitative
comparison with Lattice QCD data.Comment: 12 pages, 8 eps figures; extended discussion and reference added;
accepted in Phys. Rev.
Approximate joint measurement of qubit observables through an Arthur-Kelly type model
We consider joint measurement of two and three unsharp qubit observables
through an Arthur-Kelly type joint measurement model for qubits. We investigate
the effect of initial state of the detectors on the unsharpness of the
measurement as well as the post-measurement state of the system. Particular
emphasis is given on a physical understanding of the POVM to PVM transition in
the model and entanglement between system and detectors.Two approaches for
characterizing the unsharpness of the measurement and the resulting measurement
uncertainty relations are considered.The corresponding measures of unsharpness
are connected for the case where both the measurements are equally unsharp. The
connection between the POVM elements and symmetries of the underlying
Hamiltonian of the measurement interaction is made explicit and used to perform
joint measurement in arbitrary directions. Finally in the case of three
observables we derive a necessary condition for the approximate joint
measurement and use it show the relative freedom available when the observables
are non-orthogonal.Comment: 22 pages; Late
Critical Switching in Globally Attractive Chimeras
We report on a new type of chimera state that attracts almost all initial
conditions and exhibits power-law switching behavior in networks of coupled
oscillators. Such switching chimeras consist of two symmetric configurations,
which we refer to as subchimeras, in which one cluster is synchronized and the
other is incoherent. Despite each subchimera being linearly stable, switching
chimeras are extremely sensitive to noise: arbitrarily small noise triggers and
sustains persistent switching between the two symmetric subchimeras. The
average switching frequency scales as a power law with the noise intensity,
which is in contrast with the exponential scaling observed in typical
stochastic transitions. Rigorous numerical analysis reveals that the power-law
switching behavior originates from intermingled basins of attraction associated
with the two subchimeras, which in turn are induced by chaos and symmetry in
the system. The theoretical results are supported by experiments on coupled
optoelectronic oscillators, which demonstrate the generality and robustness of
switching chimeras
The consequences of SU(3) colorsingletness, Polyakov Loop and Z(3) symmetry on a quark-gluon gas
Based on quantum statistical mechanics we show that the color singlet
ensemble of a quark-gluon gas exhibits a symmetry through the normaized
character in fundamental representation and also becomes equivalent, within a
stationary point approximation, to the ensemble given by Polyakov Loop. Also
Polyakov Loop gauge potential is obtained by considering spatial gluons along
with the invariant Haar measure at each space point. The probability of the
normalized character in vis-a-vis Polyakov Loop is found to be maximum
at a particular value exhibiting a strong color correlation. This clearly
indicates a transition from a color correlated to uncorrelated phase or
vise-versa. When quarks are included to the gauge fields, a metastable state
appears in the temperature range due to the
explicit symmetry breaking in the quark-gluon system. Beyond
MeV the metastable state disappears and stable domains appear. At low
temperature a dynamical recombination of ionized color charges to a
color singlet confined phase is evident along with a confining
background that originates due to circulation of two virtual spatial gluons but
with conjugate phases in a closed loop. We also discuss other possible
consequences of the center domains in the color deconfined phase at high
temperature.Comment: Version published in J. Phys.
QGP Susceptibilities from PNJL Model
An improved version of the PNJL model is used to calculate various
thermodynamical quantities, {\it viz.}, quark number susceptibility, isospin
susceptibility, specific heat, speed of sound and conformal measure. Comparison
with Lattice data is found to be encouraging.Comment: 4 pages, 2 figures, poster presented at Quark Matter'0
Spatiotemporal communication with synchronized optical chaos
We propose a model system that allows communication of spatiotemporal
information using an optical chaotic carrier waveform. The system is based on
broad-area nonlinear optical ring cavities, which exhibit spatiotemporal chaos
in a wide parameter range. Message recovery is possible through chaotic
synchronization between transmitter and receiver. Numerical simulations
demonstrate the feasibility of the proposed scheme, and the benefit of the
parallelism of information transfer with optical wavefronts.Comment: 4 pages, 5 figure
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