A Generalization of Slavnov-Extended Non-Commutative Gauge Theories

We consider a non-commutative U(1) gauge theory in 4 dimensions with a modified Slavnov term which looks similar to the 3-dimensional BF model. In choosing a space-like axial gauge fixing we find a new vector supersymmetry which is used to show that the model is free of UV/IR mixing problems, just as in the previously discussed model in arXiv:hep-th/0604154. Finally, we present generalizations of our proposed model to higher dimensions.Comment: 25 pages, no figures; v2 minor correction

One-Loop Calculations for a Translation Invariant Non-Commutative Gauge Model

In this paper we discuss one-loop results for the translation invariant non-commutative gauge field model we recently introduced in arXiv:0804.1914. This model relies on the addition of some carefully chosen extra terms in the action which mix long and short scales in order to circumvent the infamous UV/IR mixing, and were motivated by the renormalizable non-commutative scalar model of Gurau et al. (cf. arXiv:0802.0791).Comment: 18 pages, v2: minor correction

Charge Screening at First Order Phase Transitions

Possibility of structured mixed phases at first order phase transitions is examined with taking into account of charge screening and surface effects. Hadron-quark phase transition in dense neutron star interior is considered, as concrete example.Comment: 15 pages, 1 figur

How robust is a 2SC quark matter phase under compact star constraints?

We study the phase structure and equation of state for two-flavor quark matter at low temperature under compact star constraints within a nonlocal chiral quark model. We find that the occurence of a two-flavor color superconducting (2SC) phase is sensitive to variations of both the formfactor of the interaction and the ratio \eta between the coupling constants in the diquark and the scalar meson channels. Our study suggests that for standard values of the coupling ratio 0.5<\eta<0.75 either the 2SC phase does not occur (Gaussian formfactor) or it exists only in a mixed phase with normal quark matter (NQ-2SC) with a volume fraction less than 20 - 40 %, occuring at high baryon chemical potentials \mu_B >1200 MeV and most likely not relevant for compact stars. We also present the relevant region of the phase diagram for compact star applications and obtain that no gapless 2SC occurs at low temperatures.Comment: 19 pages, 9 figures, Subsec.2.5: "Phase diagram" adde

A Vector Supersymmetry in Noncommutative U(1) Gauge Theory with the Slavnov Term

We consider noncommutative U(1) gauge theory with the additional term, involving a scalar field lambda, introduced by Slavnov in order to cure the infrared problem. we show that this theory, with an appropriate space-like axial gauge-fixing, wxhibits a linear vector supersymmetry similar to the one present in the 2-dimensional BF model. This vector supersymmetry implies that all loop corrections are independent of the $\lambda AA$-vertex and thereby explains why Slavnov found a finite model for the same gauge-fixing.Comment: 18 pages, 3 figures; v2 Acknowledgments adde

Renormalization of the commutative scalar theory with harmonic term to all orders

The noncommutative scalar theory with harmonic term (on the Moyal space) has a vanishing beta function. In this paper, we prove the renormalizability of the commutative scalar field theory with harmonic term to all orders by using multiscale analysis in the momentum space. Then, we consider and compute its one-loop beta function, as well as the one on the degenerate Moyal space. We can finally compare both to the vanishing beta function of the theory with harmonic term on the Moyal space.Comment: 16 page

On Batalin-Vilkovisky Formalism of Non-Commutative Field Theories

We apply the BV formalism to non-commutative field theories, introduce BRST symmetry, and gauge-fix the models. Interestingly, we find that treating the full gauge symmetry in non-commutative models can lead to reducible gauge algebras. As one example we apply the formalism to the Connes-Lott two-point model. Finally, we offer a derivation of a superversion of the Harish-Chandra-Itzykson-Zuber integral.Comment: 20 pages, LaTeX. v2: minor corrections. v3: Added an Appendix about Harish-Chandra-Itzykson-Zuber integrals. v4: Added Reference

Constraints on the high-density nuclear equation of state from the phenomenology of compact stars and heavy-ion collisions

A new scheme for testing nuclear matter equations of state (EsoS) at high densities using constraints from neutron star phenomenology and a flow data analysis of heavy-ion collisions is suggested. An acceptable EoS shall not allow the direct Urca process to occur in neutron stars with masses below $1.5~M_{\odot}$, and also shall not contradict flow and kaon production data of heavy-ion collisions. Compact star constraints include the mass measurements of 2.1 +/- 0.2 M_sun (1 sigma level) for PSR J0751+1807, of 2.0 +/- 0.1 M_sun from the innermost stable circular orbit for 4U 1636-536, the baryon mass - gravitational mass relationships from Pulsar B in J0737-3039 and the mass-radius relationships from quasiperiodic brightness oscillations in 4U 0614+09 and from the thermal emission of RX J1856-3754. This scheme is applied to a set of relativistic EsoS constrained otherwise from nuclear matter saturation properties with the result that no EoS can satisfy all constraints simultaneously, but those with density-dependent masses and coupling constants appear most promising.Comment: 15 pages, 8 figures, 5 table

Spin-one color superconductivity in compact stars?- an analysis within NJL-type models

We present results of a microscopic calculation using NJL-type model of possible spin-one pairings in two flavor quark matter for applications in compact star phenomenology. We focus on the color-spin locking phase (CSL) in which all quarks pair in a symmetric way, in which color and spin states are locked. The CSL condensate is particularly interesting for compact star applications since it is flavor symmetric and could easily satisfy charge neutrality. Moreover, the fact that in this phase all quarks are gapped might help to suppress the direct Urca process, consistent with cooling models. The order of magnitude of these small gaps (~1 MeV) will not influence the EoS, but their also small critical temperatures (T_c ~800 keV) could be relevant in the late stages neutron star evolution, when the temperature falls below this value and a CSL quark core could form.Comment: 7 pages, 7 figures, revised version, accepted for the Conference Proceedings of "Isolated Neutron Stars: from the Interior to the Surface", London, 24-28. April 200

One-loop β\beta functions of a translation-invariant renormalizable noncommutative scalar model

Recently, a new type of renormalizable $\phi^{\star 4}_{4}$ scalar model on the Moyal space was proved to be perturbatively renormalizable. It is translation-invariant and introduces in the action a $a/(\theta^2p^2)$ term. We calculate here the $\beta$ and $\gamma$ functions at one-loop level for this model. The coupling constant $\beta_\lambda$ function is proved to have the same behaviour as the one of the $\phi^4$ model on the commutative $\mathbb{R}^4$. The $\beta_a$ function of the new parameter $a$ is also calculated. Some interpretation of these results are done.Comment: 13 pages, 3 figure