A superstrong magnetic field stimulates the spontaneous production of positrons by naked nuclei by diminishing the value of the critical charge Z cr . The phenomenon of screening of the Coulomb potential by a superstrong magnetic field which has been discovered recently acts in the opposite direction and prevents the nuclei with Z < 52 from becoming critical. For Z > 52 for a nucleus to become critical stronger B are needed than without taking screening into account.

An extension of the Standard Model with an additional Higgs singlet is analyzed. Bounds on singlet admixture for the 125 GeV h boson from electroweak radiative corrections and data on h production and decays are obtained. The possibility of double h production enhancement at 14 TeV LHC due to a heavy Higgs contribution is considered.

We re-examine the physics of supercritical nuclei, specially focusing on the scattering phase δ and its dependence on the energy ε of the diving electronic level, for which we give both exact and approximate formulas. The Coulomb potential Z α/r is rounded to the constant Z α/R for r < R. We confirm the resonant behavior of δ that we investigate in detail. In addition to solving the Dirac equation for an electron, we solve it for a positron, in the field of the same nucleus. This clarifies the interpretation of the resonances. Our results are compared with claims made in previous works.

We present a model of spontaneous (or dynamical) C and CP violation where it is possible to generate domains of matter and antimatter separated by cosmologically large distances. Such C(CP ) violation existed only in the early universe and later it disappeared with the only trace of generated baryonic and/or antibaryonic domains. So the problem of domain walls in this model does not exist. These features are achieved through a postulated form of interaction between inflaton and a new scalar field, realizing short time C(CP ) violation. I. INTRODUCTIONOur local cosmological neighborhood is made of baryons, while fraction of antimatter, presumably of astrophysical origin, is vanishingly small. So the observations indicate that the universe is 100% baryo-asymmetric, at least locally. The Baryon Asymmetry (of the Universe), BAU, cannot be explained in the frameworks of the Standard Model (SM) of particle physics. Alongside with evidence for dark matter and dark energy it is considered as unambiguous proof of the existence of new physics beyond SM.Many quite different extensions of the SM and various scenarios for the BAU generation were suggested in the literature, for a review see e.g. Refs. [1][2][3][4][5]. Typically, consideration is restricted to the models where the universe is asymmetric globally. This is the simplest possibility. However, it is not excluded that the real universe may be globally symmetric. It may consist of domains of matter and antimatter, and if the domains are sufficiently large and far away, they may escape observational constraints on matter-antimatter annihilation at the domain boundaries. In the simplest version of the scenario the distance to the nearest domain of antimatter should be close to the present day cosmological horizon [6].Corresponding particle physics models, leading to the universe creation with abundant antimatter domains were suggested and developed in the past. While being more involved, the models of this type also suffer from the inherent problem -a domain wall problem [7]. Indeed, BAU can be generated only if CP violation is sufficiently strong, beyond the SM capabilities. In addition, in globally symmetric universe CP should have different signs in different domains. This non-trivial pattern of CP violation could be provided by a dedicated physical field, one way or another. Therefore, unavoidably, domains with different CP phase would be separated by domain walls with unacceptably high energy density, in conflict with observations. There is only one way out of this restriction. Namely, domains with different sign (and possibly strength) of CP violation should exist only in the universe past and should disappear by now, all together with domain walls, though their effects in the form of matter and antimatter objects would survive to the present day.One class of models where this can be achieved has been suggested in Refs. [8][9][10][11]. The main idea behind is a possibility of an unusual symmetry behavior at high temperatures. It is well known that a symmetry, whi...

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If decays of a heavy particle S are responsible for the diphoton excess with invariant mass 750 GeV observed at the 13 TeV LHC run, it can be easily accomodated in the Standard Model. Two scenarios are considered: production in gluon fusion through a loop of heavy isosinglet quark(s) and production in photon fusion through a loop of heavy isosinglet leptons. In the second case many heavy leptons are needed or/and they should have large electric charges in order to reproduce experimental data on σpp→SX · Br(S → γγ).

We consider thick domain walls in a de Sitter universe following paper by Basu and Vilenkin [1]. However, we are interested not only in stationary solutions found in [1], but also investigate the general case of domain wall evolution with time. When the wall thickness parameter, δ0, is smaller thanwhere H is the Hubble parameter in de Sitter space-time, then the stationary solutions exist, and initial field configurations tend with time to the stationary ones. However, there are no stationary solutions for δ0 ≥ H −1 / √ 2. We have calculated numerically the rate of the wall expansion in this case and have found that the width of the wall grows exponentially fast for δ0 ≫ H −1 . An explanation for the critical value δ0c = H −1 / √ 2 is also proposed. * dolgov@fe.infn.it † sgodunov@itep.ru ‡ a.s.rudenko@inp.nsk.su

We propose an approach for the search of charged long-lived particles produced in ultraperipheral collisions at the LHC. The main idea is to improve event reconstruction at ATLAS and CMS with the help of their forward detectors. Detection of both scattered protons in forward detectors allows complete recovery of event kinematics. Though this requirement reduces the number of events, it greatly suppresses the background, including the strong background from the pile-up. * sgodunov@itep.ru † novikov@itep.ru ‡ rozanov@cppm.in2p3.fr § vysotsky@itep.ru ¶ zhemchugov@itep.ru 1 arXiv:1906.08568v2 [hep-ph] 12 Jul 20191 Concentration of relic charginos would be the same as neutralinos in the standard scenario (where neutralino is the LSP). For chargino mass of the order of 100 GeV, this value would be of the same order of magnitude as protons concentration, and it is in dramatic contradiction with, e.g., the bound of 10 −28 times protons concentration from Ref. [20].