e^+e^-\to (h A)\to bbbb in Abelian Extended Supersymmetric Standard Model

We discuss the $e^{+}e^{-}\to (h A)\to bbbb$ cross section in an Abelian extended SM. We work in that minimum of the scalar potential for which Higgs trilier coupling is greater than the soft mass parameters. We find that nex-to-lightest Higgs gives the essential contribution to the cross section in the small $Z-Z'$ mixing angle and leptophobic $Z'$ limit.Comment: 13 pages, 1 postscript figur

One-Loop Effects in Supergravity Models with an Additional U(1)

For an Abelian extended Supergravity model, we investigate some important low energy parameters: \tan\beta, Z-Z' mixing angle, lightest CP-even Higgs mass bound, Z' mass, and effective \mu parameter. By integrating the RGE's from string scale down to the weak scale we constuct the scalar potential, and analyze the quantities above at the tree- and one-loop levels by including the contributions of top squarks and top quark in the effective potential. PACS: 04.65.+e, 12.60.JvComment: 16 pages, 6 postscript figure

The Wilson loop from a Dyson equation

The Dyson equation proposed for planar temporal Wilson loops in the context of supersymmetric gauge theories is critically analysed thereby exhibiting its ingredients and approximations involved. We reveal its limitations and identify its range of applicability in non-supersymmetric gauge theories. In particular, we show that this equation is applicable only to strongly asymmetric planar Wilson loops (consisting of a long and a short pair of loop segments) and as a consequence the Wilsonian potential can be extracted only up to intermediate distances. By this equation the Wilson loop is exclusively determined by the gluon propagator. We solve the Dyson equation in Coulomb gauge for the temporal Wilson loop with the instantaneous part of the gluon propagator and for the spatial Wilson loop with the static gluon propagator obtained in the Hamiltonian approach to continuum Yang-Mills theory and on the lattice. In both cases we find a linearly rising color potential.Comment: 12 pages, 7 figure

A note on the breathing mode of an elastic sphere in Newtonian and complex fluids

Experiments on the acoustic vibrations of elastic nanostructures in fluid media have been used to study the mechanical properties of materials, as well as for mechanical and biological sensing. The medium surrounding the nanostructure is typically modeled as a Newtonian fluid. A recent experiment however suggested that high-frequency longitudinal vibration of bipyramidal nanoparticles could trigger a viscoelastic response in water-glycerol mixtures [M. Pelton et al., "Viscoelastic flows in simple liquids generated by vibrating nanostructures," Phys. Rev. Lett. 111, 244502 (2013)]. Motivated by these experimental studies, we first revisit a classical continuum mechanics problem of the purely radial vibration of an elastic sphere, also called the breathing mode, in a compressible viscous fluid, and then extend our analysis to a viscoelastic medium using the Maxwell fluid model. The effects of fluid compressibility and viscoelasticity are discussed. Although in the case of longitudinal vibration of bipyramidal nanoparticles, the effects of fluid compressibility were shown to be negligible, we demonstrate that it plays a significant role in the breathing mode of an elastic sphere. On the other hand, despite the different vibration modes, the breathing mode of a sphere triggers a viscoelastic response in water-glycerol mixtures similar to that triggered by the longitudinal vibration of bipyramidal nanoparticles. We also comment on the effect of fluid viscoelasticity on the idea of destroying virus particles by acoustic resonance

Unitarity of the tree approximation to the Glauber AA amplitude for large A

The nucleus-nucleus Glauber amplitude in the tree approximation is studied for heavy participant nuclei. It is shown that, contrary to previous published results, it is not unitary for realistic values of nucleon-nucleon cross-sections.Comment: 15 pages, 1 figure, 1 table. Submitted to Yad. Fi

Q-ball formation in the MSSM with explicit CP violation

Q-balls generically exist in the supersymmetric extensions of the standard model. Taking into account the additional sources of CP violation, which are naturally accomodated by the supersymmetric models, it is shown that the Q-ball matter depends additively on individual CP phases, whereas mass per unit charge in the Q-ball depends only on the relative phases. There are regions of the parameter space where there is no stable Q-ball solution in the CP-conserving limit whereas finite CP phases induce a stable Q-ball.Comment: 6 p

Geometric approach to asymptotic expansion of Feynman integrals

We present an algorithm that reveals relevant contributions in non-threshold-type asymptotic expansion of Feynman integrals about a small parameter. It is shown that the problem reduces to finding a convex hull of a set of points in a multidimensional vector space.Comment: 6 pages, 2 figure