Modern Physics Letters A

We review recent progress in lattice QCD at nonzero temperature with emphasis on the calculations of equation of state and the properties of heavy quark–anti-quark pairs at high temperatures. We also briefly discuss the deconfinement and chiral symmetry restoring aspects of the QCD transition at finite temperature.

The measurement of baryon acoustic oscillations (BAO) from a galaxy redshift survey provides one of the most promising methods for probing dark energy. In this paper, we clarify the assumptions that go into the forecasts of dark energy constraints from BAO. We show that assuming a constant nP_0.2/G²(z) (where P_0.2 is the real space galaxy power spectrum at k = 0.2 h/Mpc and redshift z) gives a good approximation of the observed galaxy number density expected from a realistic flux-limited galaxy redshift survey. We find that assuming nP_0.2/G²(z) = 10 gives very similar dark energy constraints to assuming nP_0.2 = 3, but the latter corresponds to a galaxy number density larger than ~70% at z = 2. We show how the Figure-of-Merit (FoM) for constraining dark energy depends on the assumed galaxy number density, redshift accuracy, redshift range, survey area, and the systematic errors due to calibration and uncertainties in the theory of nonlinear evolution and galaxy biasing. We find that an additive systematic noise of up to 0.4–0.5% per Δz = 0.1 redshift slice does not lead to significant decrease in the BAO FoM.

The relativistic quantum interference effects in the spacetime of slowly rotating object in the Hořava–Lifshitz gravity as the Sagnac effect and phase shift of interfering particle in neutron interferometer are derived. We consider the extension of Kehagias–Sfetsos (KS) solution⁴⁸ in the Hořava–Lifshitz gravity for the slowly rotating gravitating object. Using the covariant Klein–Gordon equation in the nonrelativistic approximation, it is shown that the phase shift in the interference of particles includes the gravitational potential term with the KS parameter ω. It is found that in the case of the Sagnac effect, the influence of the KS parameter ω is becoming important due to the fact that the angular velocity of the locally non-rotating observer is increased in Hořava gravity. From the results of the recent experiments⁵⁰ we have obtained lower limit for the coupling KS constant as ω ≃ 1.25 ⋅10^-25cm^-2. Finally, as an example, we apply the obtained results to the calculation of the UCN (ultra-cold neutrons) energy level modification in the gravitational field of slowly rotating gravitating object in the Hořava–Lifshitz gravity.

We consider conformally invariant form of the actions in Einstein, Weyl, Einstein–Cartan and Einstein–Cartan–Weyl space in general dimensions (> 2) and investigate the relations among them. In Weyl space, the observational consistency condition for the vector field determining non-metricity of the connection can be obtained from the equation of motion. In Einstein–Cartan space a similar role is played by the vector part of the torsion tensor. We consider the case where the trace part of the torsion is the Kalb–Ramond type of field. In this case, we express conformally invariant action in terms of two scalar fields of conformal weight -1, which can be cast into some interesting form. We discuss some applications of the result.

The anapole moment of a massless charged scalar particle is studied in a model-independent fashion, using the effective Lagrangian technique, as well as radiatively within the context of scalar quantum electrodynamics (SQED). It is shown that this gauge structure is characterized by a non-renormalizable interaction, which is radiatively generated at one-loop. It is found that the resulting anapole moment for off-shell particles, though free of ultraviolet divergences, is gauge dependent and thus it is not a physical observable. We also study some of its kinematical limits. In particular, it is shown that its value comes out to be zero when the photon is on-shell and the momenta squared of the incoming and outgoing scalars are equal. It is a stronger statement than it being zero for all particles being on-shell which is required by the current conservation.

In this paper, we construct a model of spinor fields interacting with specific gauge fields on the fuzzy sphere and analyze the chiral symmetry of this "Schwinger model". In constructing the theory of gauge fields interacting with spinors on the fuzzy sphere, we take the approach that the Dirac operator D_q on the q-deformed fuzzy sphere is the gauged Dirac operator on the fuzzy sphere. This introduces interaction between spinors and specific one-parameter family of gauge fields. We also show how to express the field strength for this gauge field in terms of the Dirac operators D_q and D alone. Using the path integral method, we have calculated the 2n-point functions of this model and show that, in general, they do not vanish, reflecting the chiral non-invariance of the partition function.