Modern Physics Letters A

We review a growing theoretical motivation and evidence that the number of dimensions actually reduces at high energies. This reduction can happen near the Planck scale, or much before, the dimensions that are reduced can be effective, spectral, topological or the usual dimensions, but many things point toward the fact that the high energy theories appear to propagate in a lower-dimensional space, rather than a higher-dimensional one. We will concentrate on a particular scenario of "vanishing" or "evolving dimensions" where the dimensions open up as we increase the length scale that we are probing, but will also mention related models that point to the same direction, i.e. the causal dynamical triangulation, asymptotic safety, as well as evidence coming from a noncommutative quantum theories, the Wheeler–DeWitt equation and phenomenon of "asymptotic silence". It is intriguing that experimental evidence for the high energy dimensional reduction may already exist — a statistically significant planar alignment of events with energies higher than TeV has been observed in high altitude cosmic ray experiments. A convincing evidence for dimensional reduction may be found in future in collider experiments and gravity waves observatories.

We investigated quasinormal frequencies (QNFs) in black brane with hyperscaling violating by using the continued fractions method. We calculate QNF of massless scalar field and electromagnetic field both with zero spatial momentum, find that QNFs have negative imaginary frequency suggesting black brane with hyperscaling violation is stable under those perturbations.

We study the semiclassical Einstein equation and inflaton in the oscillatory region of the FRW Universe. We study the relative deviation of particle production in coherent and squeezed vacuum states for a minimally coupled scalar field in the oscillatory region of flat FRW Universe. We also study the behavior of inflaton field in non-oscillatory region. We examine whether the solution obtained in slow-roll approximation satisfies Klein–Gordon equation and commutation relation as well.

Newtonian fluid dynamics allows the construction of acoustic metrics from which black hole configurations can be studied. However, relativistic pressure effects are neglected within Newtonian theory. We study acoustic black holes in the framework of neo-Newtonian hydrodynamics, which is designed to take into account relativistic inertial effects of the pressure p. Within this new hydrodynamical context we show how p can influence the formation of the acoustic horizons.

In this paper, we study the sensitivity of the fraction of events arising from gluon–gluon fusion to the chromoelectric and chromomagnetic dipole moments (CEDM and CMDM) as well as the total and differential cross-sections at the LHC and Tevatron. The sensitivity of measured charged asymmetry at the LHC to CEDM and CMDM is also studied. We find that at the Tevatron and the LHC, nonzero values of CMDM could suppress the production rate. It is shown that the ratio of at the Tevatron is more sensitive to CEDM and CMDM than the LHC case. The presence of CEDM always increases the contribution of gluon–gluon fusion process in top pair rate at the Tevatron and LHC. Except for a small range of CMDM, the presence of CEDM and CMDM can increase the fraction of gluon–gluon fusion at the Tevatron and LHC. The measured ratio of at the Tevatron is used to derive bounds on the chromoelectric and chromomagnetic dipole moments as well as the total and differential cross-sections at the LHC and Tevatron, and the measured charged asymmetry at the LHC. The combination of and σ_LHC provides stringent limits on CMDM and CEDM.

We consider Little Rip (LR) and Pseudo Rip (PR) cosmological models with two interacting ideal fluids, corresponding to dark energy and dark matter. The interaction between the dark energy and the dark matter fluid components is described in terms of the parameters in the equations of state for the LR and PR universes. In contrast to a model containing only a pure dark energy, the presence of the interaction term between the fluid components in the gravitational equations leads to a modification of the equation of state parameters. The properties of the early universe in this formalism are pointed out.

Behavior of some average characteristics of protons are studied in protons and deuterons induced interactions with carbon nuclei at 4.2 A GeV/c. The emitted particles are divided into two groups depending on their polar angle in the lab. frame using half angle technique. Results of the experimental data are compared with Dubna version of cascade model. Analysis of the results show that the inner cone protons are leading particles.