14417029
Asymptotes of solutions of a perfect fluid coupled with a cosmological constant in four-dimensional spacetime with toroidal symmetry
AbstractAsymptotes of solutions of a perfect fluid when coupled with a cosmological constant in four-dimensional spacetime with toroidal symmetry are studied. In particular, it is found that the problem of self-similar solutions of the first kind for a fluid with the equation of state, p = kρ, can be reduced to solving a master equation of the form,

$$ 2 F(q, k)\frac{q''(\xi)}{q'(\xi)} - G(q,k) q'(\xi) = \frac{4}{\xi}. $$

For k = 0 and k = −1/3 the general solutions are obtained and their main local and global properties are studied in detail.
2444705
Gravitational and particle radiation from long cosmic strings
Gravitational and massless particle radiation from infinitely long cosmic strings with finite thickness is studied by constructing analytic solutions to the Einstein field equations with certain forms of energy - momentum tensor. Using Thorne's -energy arguments, it is shown that the radiation always carries away energy. As a result, the angle defect outside the string is less than that in the non-radiation case. Since the solutions are exact, the back reaction of the radiation is automatically taken into account. In fact, it is shown that because of this back reaction the spacetime is always singular on the symmetry axis. The singularity is a scalar one and not removable.
119227824
Cosmological constant and late transient acceleration of the universe in the Horava-Witten Heterotic M-Theory on S^{1}/Z_{2}
Abstract Orbifold branes are studied in the framework of the 11-dimensional Horava–Witten heterotic M-theory. It is found that the effective cosmological constant can be easily lowered to its current observational value by the mechanism of large extra dimensions. The domination of this constant over the evolution of the universe is only temporary. Due to the interaction of the bulk and the branes, the universe will be in its decelerating expansion phase again in the future, whereby all problems connected with a far future de Sitter universe are resolved.
10393301
On the sources of static plane symmetric vacuum space-times
Abstract The sources of static vacuum plane space-times with reflection symmetry are considered. It is argued that the counterpart of the Einstein theory to the gravitational field of a massive Newtonian plane should be described by the Rindler solution, which represents also a uniform gravitational field, and the test particles moving in which have constant accelerations.
109935503
No-Go theorem in spacetimes with two commuting spacelike killing vectors
Four-dimensional Riemannian spacetimes with two commuting spacelike Killing vectors are studied in Einstein's theory of gravity, and found that no outer apparent horizons exist, provided that the dominant energy condition holds.
119168760
Homothetic self-similar solutions of three-dimensional Brans-Dicke gravity
All homothetic self-similar solutions of the Brans-Dicke scalar field in three-dimensional spacetime with circular symmetry are found in closed form.
117264492
Reply to Comment of Gazdzicki and Heinz on Strangeness Enhancement in $p+A$ and $S+A$
The Comment of Gazdzicki and Heinz is flawed because their assumed baryon stopping power in $pA$ is inconsistent with data and because they ignored half the analysis based on the VENUS model. The Comment continues the misleading presentation of strangeness enhancement by focusing on ratios of integrated yields. Those ratios discard essential experimental information on the rapidity dependence of produced $\Lambda$ and obscure discrepancies between different data sets. Our conclusion remains that the NA35 minimum bias data on $p+S\rightarrow\Lambda +X $ indicate an anomalous enhancement of central rapidity strangeness in few nucleon reactions that points to non-equilibrium dynamics as responsible for strangeness enhancement in nuclear reactions.
123322377
PLANAR DOMAIN WALLS COUPLED WITH PURE RADIATION FIELDS
All the exact solutions of the Einstein-Maxwell-Weyl equations are given, which represent planar domain walls coupled with electromagnetic and neutrino radiation fields. Some specific solutions are studied.
118411966
Elastic Scattering of Positive Kaons on Polarized Deuterons at 1.5 Gev/c.
121101159
Effect of a preshower detector on calorimetry performance
Abstract Test beam results obtained with a preshower detector in a SDC calorimetry configuration are presented. The benefits of independently instrumenting the first scintillating tile of each tower of the tile/fiber electromagnetic calorimeter, forming the analogue of the “Massless Gap” in LAr calorimeters, are demonstrated. Electron and pion data were taken with a calorimeter configured with one or two radiation lengths of inert material in front, a scintillating fiber preshower detector, a tile/fiber electromagnetic calorimeter, a shower maximum detector, and a tile/fiber hadron calorimeter. The energy deposited in the scintillating fibers of the preshower detector was summed to simulate the preshower energy that would be detected by the first scintillating tile of an EMC tower. The data were collected in the MP9 beam line at Fermilab during the Summer and Fall of 1991. The relative degradation in electromagnetic energy resolution due to the inert material in front of the electromagnetic calorimeter was measured. The resolution is improved by adding in the properly weighted preshower energy. The charged pion rejection versus electron acceptance is presented for combined cuts using the electromagnetic and hadronic calorimeters, with the energy deposited in the preshower and shower maximum detectors. We show that, even after calorimetric and shower maximum cuts, the pion rejection is further improved by using the preshower energy.
5973680
Shear-free radiating collapse and conformal flatness
Here we study some general properties of spherical shear-free collapse. Its general solution when imposing conformal atness is re-obtained (Refs. 1 and 2) and matched to the outgoing Vaidya spacetime. We propose a simple model satisfying these conditions and study its physical consequences. Special attention deserve, the role played by relaxational processes and the conspicuous link betweeen dissipation and density inhomogeneity.