Modern Physics Letters A

We show that the cascade limit on ultra high energy cosmic neutrino (UHECν) flux imposes a lower bound on the neutrino mass, provided that super-GZK events of ultra high energy cosmic rays (UHECRs) are produced from Z-bursts. Based on data from HiRes and AGASA, the lower bound obtained on neutrino mass violates its existing cosmological upper bound. We conclude that Z-bursts cannot be the dominant source for the observed super-GZK UHECR events. This is consistent with the recent ANITA-lite data.

We make a first crude direct estimate of the net gluon polarization in the proton, ΔG, combining data on the asymmetries in high-p_T hadron production from the HERMES, SMC and COMPASS collaborations. Although these data sample a restricted range of x, they provide no hint that ΔG is large. Fixing the normalizations of different theoretical parametrizations using the hadron asymmetry data, we find typical central values of ΔG ~ 0.5, with uncertainties of similar magnitude. Values of ΔG≥2 are disfavored by Δχ² ~ 9 to 20, depending on the parametrization used.

We consider cosmological implications of the formula for the dark energy density derived by Gurzadyan and Xue^1,2 which predicts a value fitting the observational one. Cosmological models with varying by time physical constants, namely, speed of light and gravitational constant and/or their combinations, are considered. In one of the models, for example, vacuum energy density induces effective negative curvature, while another one has an unusual asymptotic. This analysis also explicitly rises the issue of the meaning and content of physical units and constants in cosmological context.

The possibility that the strength of gravitational interactions might slowly increase with distance, is explored by formulating a set of effective field equations, which incorporate the gravitational, vacuum-polarization induced, running of Newton's constant G. The resulting long distance (or large time) behavior depends on only one adjustable parameter ξ, and the implications for the Robertson–Walker universe are calculated, predicting an accelerated power-law expansion at later times t ~ ξ ~ 1/H.

In the framework of meson–meson mixing, in the presence of the a₄(2040), and f₄(2050) being the 1 ³F₄ states, we suggest that the f′₄, the ninth member of the 1 ³F₄ meson nonet, has a mass of about 2084 MeV, and some predictions on the f₄ and f′₄ decaying into two photons and pseudoscalar mesons are presented. Also, the mass of the lowest lying 4⁺⁺ glueball is predicted to be about 3.15 GeV by using the meson-glueball mass relation derived from the glueball dominance picture, which is in agreement with 3.42 GeV, the average value of the recent predicted results was given by lattice QCD, potential model, semi-relativistic potential model and quasi-particle model.

Black hole solutions in higher dimensional Einstein and Einstein–Maxwell gravity have been discussed by Tangherlini as well as Myers and Perry a long time ago. These solutions are the generalizations of the familiar Schwarzschild, Reissner–Nordström and Kerr solutions of four-dimensional general relativity. However, higher dimensional generalization of the Kerr–Newman solution in four dimensions has not been found yet. As a first step in this direction we shall report on a new solution of the Einstein–Maxwell system of equations that describes an electrically charged and slowly rotating black hole in five dimensions.

The large-N limit of fermionic vectors models is studied using bilocal variables in the framework of a collective field theory approach. The large-N configuration is determined completely using only classical solutions of the model. Further, the Bethe–Salpeter equations of the model are cast as a Green's function problem. One of the main results of this work is to show that this Green's function is in fact the large-N bilocal itself.