1,055 research outputs found

### Bulk viscosity of strange quark matter: Urca versus non-leptonic processes

A general formalism for calculating the bulk viscosity of strange quark
matter is developed. Contrary to the common belief that the non-leptonic
processes alone give the dominant contribution to the bulk viscosity, the
inclusion of the Urca processes is shown to play an important role at
intermediate densities when the characteristic r-mode oscillation frequencies
are not too high. The interplay of non-leptonic and Urca processes is analyzed
in detailComment: 9 pages, 4 figures, v2: revised figures, no change in result

### The Kerr theorem and multiparticle Kerr-Schild solutions

We discuss and prove an extended version of the Kerr theorem which allows one
to construct exact solutions of the Einstein-Maxwell field equations from a
holomorphic generating function $F$ of twistor variables. The exact
multiparticle Kerr-Schild solutions are obtained from generating function of
the form $F=\prod_i^k F_i,$ where $F_i$ are partial generating functions for
the spinning particles $i=1...k$. Solutions have an unusual multi-sheeted
structure. Twistorial structures of the i-th and j-th particles do not feel
each other, forming a type of its internal space. Gravitational and
electromagnetic interaction of the particles occurs via the light-like singular
twistor lines. As a result, each particle turns out to be `dressed' by singular
pp-strings connecting it to other particles. We argue that this solution may
have a relation to quantum theory and to quantum gravity.Comment: 13 pages, 4 figures, revtex. Expressions for electromagnetic field
are correcte

### Nonlinear Realization of the Local Conform-Affine Symmetry Group for Gravity in the Composite Fiber Bundle Formalism

A gauge theory of gravity based on a nonlinear realization (NLR) of the local
Conform-Affine (CA) group of symmetry transformations is presented. The coframe
fields and gauge connections of the theory are obtained. The tetrads and
Lorentz group metric are used to induce a spacetime metric. The inhomogenously
transforming (under the Lorentz group) connection coefficients serve as
gravitational gauge potentials used to define covariant derivatives
accommodating minimal coupling of matter and gauge fields. On the other hand,
the tensor valued connection forms serve as auxillary dynamical fields
associated with the dilation, special conformal and deformational (shear)
degrees of freedom inherent in the bundle manifold. The bundle curvature of the
theory is determined. Boundary topological invariants are constructed. They
serve as a prototype (source free) gravitational Lagrangian. The Bianchi
identities, covariant field equations and gauge currents are obtained.Comment: 24 pages. to appear in IJGMM

### Integral functions of electron lateral distribution and their fluctuations in electron-photon cascades

Monte Carlo simulated lateral distribution functions for electrons of EPC developing in lead, at superhigh energies (.1-1 PeV) for depths t or = 60 c.u. delta t=1t. c.u. are presented. The higher moment characteristics, i.e., variation, asymmetry, excess, are presented along with analytical solutions for the same characteristics at fixed observation level calculated to theory approximations A and B by using numerical inversion of the Laplace transformation. The conclusion is made of a complex, usually non-Gaussian shape of the function of the particle number distribution within a circle of given radius at fixed depth

### Lateral-angular and temporal characteristics of EAS optical radiation

Characteristics of the direct and scattered components of electron-photon shower optical radiation for distances R 500 m from the shower core to a detector, allowing for the Cerenkov and fluorescent mechanism of photon generation are presented. The results of calculations are employed to clarify the techniques for determination of the shower parameters detected by both installations registering fluorescent light and those recording Cerenkov light

### Alignment in Gamma-Hadron Families of Cosmic Rays

Alignment of main fluxes of energy in a target plane is found in families of
cosmic ray particles detected in deep lead X-ray chambers. The fraction of
events with alignment is unexpectedly large for families with high energy and
large number of hadrons. This can be considered as evidence for the existence
of coplanar scattering of secondary particles in interaction of particles with
superhigh energy, $E_0 > 10^{16}$ eV. Data analysis suggests that production of
most aligned groups occurs low above the chamber and is characterized by a
coplanar scattering and quasiscaling spectrum of secondaries in the
fragmentation region. The most elaborated hypothesis for explanation of
alignment is related to the quark-gluon string rupture. However, the problem of
theoretical interpretation of our results still remains open.Comment: 15 pages, 2 tables, 6 figures (not included), Stanford University
preprint SU-ITP-94-2

### SOME PROPERTIES OF THE KERR SOLUTION TO LOW ENERGY STRING THEORY

The Kerr solution to axidilaton gravity is analyzed in the
Debney--Kerr--Schild formalism. It is shown that the Kerr principal null
congruence retains its property to be geodesic and shear free, however, the
axidilatonic Kerr solution is not algebraically special. A limiting form of
this solution is considered near the ring-like Kerr singularity. This limiting
solution coincides with the field around a fundamental heterotic string
obtained by Sen.Comment: 14 pages., LaTe

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