119121158
New Bayesian analysis of hybrid EoS constraints with mass-radius data for compact stars
We suggest a new Bayesian analysis using disjunct mass and radius constraints for extracting probability measures for cold, dense nuclear matter equations of state. One of the key issues of such an analysis is the question of a deconfinement transition in compact stars and whether it proceeds as a crossover or rather as a first order transition. The latter question is relevant for the possible existence of a critical endpoint in the QCD phase diagram under scrutiny in present and upcoming heavy-ion collision experiments.
119222844
Kinetics of Photon Radiation off an e–e+-Plasma Created from the Vacuum in a Strong Laser Field
We consider the one-photon annihilation mechanism in a electron - positron quasiparticle plasma (EPP) created from the vacuum in a strong subcritical laser field due to the dynamical Schwinger mechanism. On the basis of a kinetic theory approach we show that the secondary photons have a radiation spectrum proportional to 1/k (flicker noise). This effect is very small for EPP excitations in the optical spectrum but can reach quite observable values in the γ -ray region (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
119202592
Thermodynamic Instabilities in Dynamical Quark Models with Complex Conjugate Mass Poles
We show that the Cornwall-Jackiw-Tomboulis thermodynamic potential of dynamical quark models with a quark propagator represented by complex conjugate mass poles inevitably exhibits thermodynamic instabilities. We find that the minimal coupling of the quark sector to a Polyakov loop potential can strongly suppress but not completely remove such instabilities. This general effect is explicitly demonstrated in the framework of a covariant, chirally symmetric, effective quark model.
118475829
Chiral condensate and the structure of hadrons
A model of hadron masses based on the quark structure of hadrons combined with effects of chiral dynamics is used to calculate the 2+1 flavour chiral condensate in the hadron resonance gas framework. Results are discussed in the context of recent lattice QCD data. Improvements of the dynamical models of hadron structure are suggested with the aim to estimate the strange sigma term of the nucleon.
5817770
Cooling of neutron stars with color superconducting quark cores
We show that within a recently developed nonlocal chiral quark model the critical density for a phase transition to color superconducting quark matter under neutron star conditions can be low enough for these phases to occur in compact star configurations with masses below 1.3 M ⊙ . We study the cooling of these objects in isolation for different values of the gravitational mass and argue that, if the quark matter phase would allow unpaired quarks, the corresponding hybrid stars would cool too fast. The comparison with observational data puts tight constraints on possible color superconducting quark matter phases. Possible candidates with diquark gaps of the order of 10 keV - 1 MeV such as the "2SC+X" and the color spin locking (CSL) phase are presented.
44204788
Chiral Condensate and Mott–Anderson Freeze-Out
We present the idea of a Mott–Anderson freeze-out that suggests a key role of the localization of the hadron wave functions when traversing the hadronization transition. The extension of hadron wave functions in dense matter is governed by the behavior of the chiral quark condensate such that its melting at finite temperatures and chemical potentials entails an increase of the size of hadrons and thus their geometrical strong interaction cross sections. It is demonstrated within a schematic resonance gas model, that a kinetic freeze-out condition reveals a correlation with the reduction of the chiral condensate in the phase diagram up to 50% of its vacuum value. Generalizing the description of the chiral condensate by taking into account a full hadron resonance gas such correlation gets distorted. We discuss, that this may be due to our approximations in calculating the chiral condensate which disregard both, in-medium effects on hadron masses and hadron–hadron interactions. The latter, in particular due to quark exchange reactions, could lead to a delocalization of the hadron wave functions in accordance with the picture of a Mott–Anderson transition.
5623998
Wong's Equations and Charged Relativistic Particles in Non-Commutative Space
In analogy to Wong's equations describing the motion of a charged relativistic point particle in the presence of an external Yang{Mills field, we discuss the motion of such a particle in non-commutative space subject to an external U?(1) gauge field. We conclude that the latter equations are only consistent in the case of a constant field strength. This formulation, which is based on an action written in Moyal space, provides a coarser level of description than full QED on non-commutative space. The results are compared with those obtained from the different Hamiltonian approaches. Furthermore, a continuum version for Wong's equations and for the motion of a particle in non-commutative space is derived.
118456161
Heat kernel expansion and induced action for matrix models
In this proceeding note, I review some recent results concerning the quantum effective action of certain matrix models, i.e. the supersymmetric IKKT model, in the context of emergent gravity. The absence of pathological UV/IR mixing is discussed, as well as dynamical SUSY breaking and some relations with string theory and supergravity.
1425207
Divergences in non-commutative gauge theories with the Slavnov term
The divergence structure of non-commutative gauge field theories (NCGFT) with a Slavnov extension [1],[2] is examined at one-loop level with main focus on the gauge boson self-energy. Using an interpolating gauge we show that even with this extension the quadratic IR divergence of the gauge boson self-energy is independent from a covariant gauge fixing as well as from an axial gauge. The proposal of Slavnov is based on the fact that the photon propagator shows a new transversality condition with respect to the IR dangerous terms. This novel transversality is implemented with the help of a new dynamical multiplier field. However, one expects that in physical observables such contributions disappear. A further new feature is the existence of new UV divergences compatible with the gauge invariance (BRST symmetry). We then examine two explicit models with couplings to fermions and scalar fields.
119279267
On non-commutative U⋆(1) gauge models and renormalizability
Based on our recent findings regarding (non-)renormalizability of non-commutative U(1) gauge theories [1, 2] we present the construction of a new type of model. By introducing a soft-breaking term in such a way that only the bilinear part of the action is modified, no interaction between the gauge sector and auxiliary fields occurs. Demanding in addition that the latter form BRST doublet structures, this leads to a minimally altered non-commutative U(1) gauge model featuring an IR damping behavior. Moreover, the new breaking term is shown to provide the necessary structure in order to absorb the inevitable quadratic IR divergences appearing at one-loop level in theories of this kind. In this paper we compute Feynman rules, symmetries and results for the vacuum polarization together with the one-loop renormalization of the gauge boson propagator and three-point functions.
118487540
Extended BRST formulation of a non-commutative $U_*(1)$ gauge model
In this short letter, we rediscuss the model for non-commutative U⋆(1) gauge theory presented in [arXiv:0912.2634] and argue that by treating the ”soft-breaking terms” of that model in the realm of an extended BRST symmetry, a future renormalization proof using Algebraic Renormalization should be possible despite the fact that the non-commutative model is non-local. In fact, the non-localities could be treated in a way similar to commutative gauge theories with axial gauge fixing where certain non-local poles appear.