Dynamical nucleus-nucleus potential and incompressibility of nuclear matter

The dynamical nucleus-nucleus potentials for some fusion reactions are investigated by using the improved quantum molecular dynamics (ImQMD) model with different sets of parameters in which the corresponding incompressibility coefficient of nuclear matter is different. Two new sets of parameters SKP* and IQ3 for the ImQMD model are proposed with the incompressibility coefficient of 195 and 225 MeV, respectively. The measured fusion excitation function for 16O+208Pb and the charge distribution of fragments for Ca+Ca and Au+Au in multi-fragmentation process can be reasonably well reproduced. Simultaneously, the influence of the nuclear matter incompressibility and the range of nucleon-nucleon interaction on the nucleus-nucleus dynamic potential is investigated.Comment: 7 figures, 3 tables, to appear in Phys. Rev.

Phase transition in multi-scalar-singlet extensions of the Standard Model

We propose a generalization of the Standard Model (SM) by adding two real gaugesinglets S1, S2. The field S1 will improve the strength of the electroweak phase transition (EWPT). Imposing a Z2 symmetry on the field S2 makes this field a possible candidate for dark matter. Both singlets interact with other observable fields through Higgs boson. They are allowed to interact with each other as well. We find that by introducing two different scalar fields, the model is less vulnerable to experimental constraints. In this paper, we consider the effects of a heavy scalar(M1 > MH) on the electroweak phase transition. And we present configurations that produce a strong first order EWPT

Braneworld inflation

We discuss various realizations of the four dimensional braneworld inflation in warped geometries of string theory. In all models the inflaton field is represented by a Dp probe brane scalar specifying its position in the warped throat of the compactification manifold. We study existing inflationary throat local geometries, and construct a new example. The inflationary brane is either a D3- or a D5-brane of type IIB string theory. In the latter case the inflationary brane is wrapping a two-cycle of the compactification manifold. We discuss some phenomenological aspects of the model where slow-roll conditions are under computational control.Comment: 31 pages + 6 figures, v2: published PRD versio

Type N Spacetimes as Solutions of Extended New Massive Gravity

We study algebraic type N spacetimes in the extended new massive gravity (NMG), considering both the Born-Infeld model (BI-NMG) and the model of NMG with any finite order curvature corrections. We show that for these spacetimes, the field equations of BI-NMG take the form of the massive (tensorial) Klein-Gordon type equation, just as it happens for ordinary NMG. This fact enables us to obtain the type N solution to BI-NMG, utilizing the general type N solution of NMG, earlier found in our work. We also obtain type N solutions to NMG with all finite order curvature corrections and show that, in contrast to BI-NMG, this model admits the critical point solutions, which are counterparts of "logarithmic" AdS pp-waves solutions of NMG.Comment: 6 pages, twocolumn REVTe