International Journal of Modern Physics A

The process of stop-chargino production at LHC has been calculated in the Minimal Supersymmetric Standard Model at the complete electroweak one-loop level, assuming a mSUGRA symmetry breaking scheme. Several properties of the angular and invariant mass distributions of the basic amplitudes have been derived. For a meaningful collection of different benchmark points the overall electroweak one-loop effects are at most of the order of a few percent. At the realistically expected LHC accuracy, the main supersymmetric electroweak features of the process can be therefore essentially derived in this theoretical scheme from the simple Born level expressions.

We construct a free field realization of the elliptic quantum algebra for arbitrary level k ≠ 0, -N. We study Drinfeld current and the screening current associated with for arbitrary level k. In the limit p → 0 this realization becomes q-Wakimoto realization for .

By gauging an Abelian electromagnetic solution through a non-Abelian transformation and in accordance with a theorem proved long time ago, we construct a simple class of colliding Einstein–Yang–Mills plane waves. The solution is isometric to the Wu–Yang charged Kerr–Newman black hole and shares much of the properties satisfied by colliding Einstein–Maxwell plane waves. In the linear polarization limit with unit degenerate charge it reduces to the Bell–Szekeres solution for colliding em shock waves.

We argue that the consistent implementation of the multiple point principle (MPP) in the general nonsupersymmetric two-Higgs doublet model (2HDM) can lead to a set of approximate global custodial symmetries that ensure CP conservation in the Higgs sector and the absence of flavor changing neutral currents (FCNC) in the considered model. In particular, the existence of a large set of degenerate vacua at some high energy scale Λ caused by the MPP can result in approximate U(1) and Z₂ symmetries that suppress FCNC and CP-violating interactions in the 2HDM. We explore the renormalization group (RG) flow of the Yukawa and Higgs couplings within the MPP inspired 2HDM with approximate custodial symmetries and show that the solutions to the RG equations are focused near quasifixed points at low energies if the MPP scale Λ is relatively high. We study the Higgs spectrum and couplings near the quasifixed point at moderate values of tan β and compute a theoretical upper bound on the lightest Higgs boson mass. If Λ ≳ 10¹⁰GeV the lightest CP-even Higgs boson is always lighter than 125 GeV. When the MPP scale is low, the mass of the lightest Higgs particle can reach 180–220 GeV while its coupling to the top quark can be significantly larger than in the SM, resulting in the enhanced production of Higgs bosons at the LHC. Other possible scenarios that appear as a result of the implementation of the MPP in the 2HDM are also discussed.

Recent works have shown the important role nonlinear electrodynamics (NLED) can have in two crucial questions of cosmology, concerning particular moments of its evolution for very large and for low-curvature regimes, that is for very condensed phase and at the present period of acceleration. We present here a toy model of a complete cosmological scenario in which the main factor responsible for the geometry is a nonlinear magnetic field which produces a Friedmann–Robertson–Walker homogeneous and isotropic geometry. In this scenario we distinguish four distinct phases: a bouncing period, a radiation era, an acceleration era, and a re-bouncing period. It has already been shown that in NLED a strong magnetic field can overcome the inevitability of a singular region typical of linear Maxwell theory; on the other extreme situation, that is for very weak magnetic field it can accelerate the expansion. The present model goes one step further: after the acceleration phase the universe re-bounces and enters into a collapse era. This behavior is a manifestation of the invariance under the dual map of the scale factor a(t) → 1/a(t), a consequence of the corresponding inverse symmetry of the electromagnetic field (F → 1/F, where F ≡ F^μνF_μν) of the NLED theory presented here. Such sequence collapse–bouncing–expansion–acceleration–re-bouncing–collapse constitutes a basic unitary element for the structure of the universe that can be repeated indefinitely yielding what we call a cyclic magnetic universe.

We apply a recently proposed Kerr/CFT correspondence to extremal supersymmetric five-dimensional charged spinning black holes, constructed by Breckenridge, Myers, Peet and Vafa. By computing the central charge of the dual CFT and Frolov–Thorne temperature, Cardy's formula succeeds in reproducing Bekenstein–Hawking area law.

We investigate the modifications of the Hawking radiation by the Generalized Uncertainty Principle (GUP) and the tunneling process. By using the GUP-corrected de Broglie wavelength, the squeezing of the fundamental momentum cell, and consequently a GUP-corrected energy, we find the nonthermal effects which lead to a nonzero statistical correlation function between probabilities of tunneling of two massive particles with different energies. Then the recovery of part of the information from the black hole radiation is feasible. From the other point of view, the inclusion of the effects of quantum gravity as the GUP expression can halt the evaporation process, so that a stable black hole remnant is left behind, including the other part of the black hole information content. Therefore, these features of the Planck-scale corrections may solve the information problem in black hole evaporation.

The recent classification scheme of so-called adinkraic off-shell supermultiplets of N-extended worldline supersymmetry without central charges finds a combinatorial explosion. Completing our earlier efforts, we now complete the constructive proof that all of these trillions or more of supermultiplets have a superfield representation. While different as superfields and supermultiplets, these are still super-differentially related to a much more modest number of minimal supermultiplets, which we construct herein.

The type IIA nonsupersymmetric meta-stable brane configuration consisting of three NS5-branes, D4-branes and anti-D4-branes where the electric gauge theory superpotential has a quartic term for the bifundamentals besides a mass term is constructed. By adding the orientifold 4-plane and 6-plane to this brane configuration, we also describe the intersecting brane configurations of type IIA string theory corresponding to the meta-stable nonsupersymmetric vacua of corresponding gauge theories.

We investigate the entropy in a scalar O(N) model with a spontaneously broken symmetry. The Cornwall–Jackiw–Tomboulis formalism is applied to derive the entropy in the Hartree and Hartree–Fock approximations. In contrast to the Hartree approximation where the particles are quasiparticles with vanishing decay width, the Hartree–Fock approximation contains exchange contributions, which lead to nonzero decay width. We find that the sunset diagrams contribution is very small. Furthermore, the decay widths from these diagrams are discussed in the weak and strong coupling cases.