Modern Physics Letters A

We present 2D simulations of pair-instability supernovae considering rapid rotation during their explosion phases. Recent studies of the Population III (Pop III) star formation suggested that these stars could be born with a mass scale about 100 M_⊙ and with a strong rotation. Based on stellar evolution models, these massive Pop III stars might have died as highly energetic pair-instability supernovae. We perform 2D calculations to investigate the impact of rotation on pair-instability supernovae. Our results suggest that rotation leads to an aspherical explosion due to an anisotropic collapse. If the first stars have a 50% of keplerian rotational rate of the oxygen core before their pair-instability explosions, the overall ⁵⁶Ni production can be significantly reduced by about two orders of magnitude. An extreme case of 100% keplerian rotational rate shows an interesting feature of fluid instabilities along the equatorial plane caused by non-synchronized and non-isotropic ignitions of explosions, so that the shocks run into the in-falling gas and generate the Richtmyer–Meshkov instability.

We point out a possible mechanism by which the electroweak hierarchy problem can be avoided in the low energy effective quantum field theory. Assuming the existence of a UV complete underlying fundamental theory and treating the cutoff scale Λ of the effective field theory as a real physical scale we argue that the hierarchy problem would be solved if the coefficient in front of quadratic divergences vanished at the scale Λ, and if the effective theory mass parameters fixed at Λ by the fundamental theory were hierarchically smaller than Λ itself. While this mechanism most probably cannot work in the Standard Model if the scale Λ is to be close to the Planck scale, we show that it can work in a minimal extension (Conformal Standard Model) proposed recently for a different implementation of conformal symmetry breaking.

Particle tunneling from a quantum corrected black hole in the gravity's rainbow was investigated by the radial trajectory method of the tunneling framework. Using the thermodynamic property of the event horizon, a simpler method for calculating the tunneling probability was shown. In this method, the Painleve coordinate transformation of spacetime and the radial trajectory equation of the tunneling particles used in the previous radial trajectory method was not used. Using the simpler method, the tunneling probability of outgoing particles, regardless of whether they are massless or massive, were calculated in a unified way. The emission rates were related to the changes of the black hole entropies before and after the emission. This implies that the emission spectrum agrees with the underling unitary theory. In addition, the Bekenstein–Hawking area for the modified black hole was established and the emission spectrum with quantum corrections was discussed.

A dynamical system analysis related to Dirac–Born–Infeld (DBI) cosmological model has been investigated in this present work. For spatially flat FRW spacetime, the Einstein field equation for DBI scenario has been used to study the dynamics of DBI dark energy interacting with dark matter. The DBI dark energy model is considered as a scalar field with a nonstandard kinetic energy term. An interaction between the DBI dark energy and dark matter is considered through a phenomenological interaction between DBI scalar field and the dark matter fluid. The field equations are reduced to an autonomous dynamical system by a suitable redefinition of the basic variables. The potential of the DBI scalar field is assumed to be exponential. Finally, critical points are determined, their nature have been analyzed and corresponding cosmological scenario has been discussed.

The SU(3) classification of baryon number B = 2, that is dibaryon sextaquarks, is considered. It is noted that the deuteron belongs to the 10* representation. Sum rules in broken SU(3) are given for the 10* and 10 dibaryons into B(8)+B(8). Finally, the possibility of observing the dibaryons in low energy pp- and e⁺e^--collisions is discussed.

Here, we consider a gravity theory involving a spontaneous Lorentz symmetry breaking called the bumblebee model. We show that, at certain values of the bumblebee field, the Gödel metric is consistent within this theory.

This is revision of the S-Matrix theory of neutrino oscillations used for many years. We evaluate the transition probability of a μ to e neutrino without an approximation used for many theoretical studies, and find important differences which could improve the extraction of neutrino parameters from experimental data in the future.