A. Nicolaidis

A simple parametrization of the structure functions of the photon

Abstract A simple method is proposed for parametrizing the structure functions of the photon. After factoring out the singular behavior at x ⋍ 0 , the structure functions are expanded in series of Jacobi polynomials. For the distribution functions of quark and gluon within a photon and the fragmentation function of a quark into a photon only three or five terms are needed to reproduce the x -dependence accurately over the entire x -range.

Neutrinos for geophysics

Abstract The Mikheyev-Smirnov-Wolfenstein solution to the solar-neutrino deficit provides a range for the acceptable neutrino parameters ( Δm 2 and sin 2θ 0 ). If the vacuum mixing angle θ 0 is not too small, the resulting neutrino oscillation length in matter is comparable to the radius of the earth. For such appropriate neutrino parameters we study neutrino oscillations inside the earth. The core of the earth is taken as a sphere with constant density 11 g/cm 3 , while the mantle, surrounding the core, is taken to be a spherically symmetric shell of constant density 4.4 g/cm 3 . We obtain an exact, analytic expression for the probability that an electron-neutrino after traversing the earth, emerges as an electron-neutrino. Our results indicate that the neutrinos might serve as the ideal tools for earth tomography.

Shadowing of ultrahigh-energy neutrinos

Abstract The rise with energy of the neutrino-nucleon cross section implies that at energies above few TeV the Earth is becoming opaque to cosmic neutrinos. The neutrinos interact with the nucleons through the weak charged current, resulting into absorption, and the weak neutral current, which provides a redistribution of the neutrino energy. We Mellin transform the neutrino transport equation and find its exact solution in the moment space. A simple analytical formula is provided, which describes accurately the neutrino spectrum, after the neutrinos have traversed the Earth. The effect of the weak neutral current is most prominent for an initial flat neutrino spectrum and we find that at low energies (around 1 TeV) the neutrino intensity is even enhanced.

NEUTRINO TOMOGRAPHY OF THE EARTH

Neutrino oscillations inside matter are very sensitive to the density of the medium traversed by the neutrinos. If the neutrino mixing angle (so far unknown) is not very small, then the neutrino oscillation length is of the size of the Earth, and we can use the phenomenon of neutrino matter oscillations to study the Earths density distribution. Although neutrino attenuation data have already been proposed as a means to infer the density structure of the Earth, we show that neutrino oscillation data could also be used to make a density tomograph of the Earth. A numerical experiment in which neutrino beams from an accelerator are sent across the Earth, and are detected at six different locations on the Earths surface, shows the feasibility of using neutrino oscillation data, with the advantage of using only currently available neutrino energies.

STRING QUANTIZATION IN CURVED SPACETIMES: NULL STRING APPROACH

We study quantum strings in strong gravitational fields. The relevant small parameter is where Rc is the curvature of the spacetime and T0 is the string tension. Within our systematic expansion we obtain to zeroth-order the null string (string with zero tension), while the first-order correction incorporates the string dynamics. We apply our formalism to quantum null strings in de Sitter spacetime. After a reparametrization of the worldsheet coordinates, the equations of motion are simplified. The quantum algebra generated by the constraints is considered, ordering the momentum operators to the right of the coordinate operators. No critical dimension appears. It is anticipated, however, that the conformal anomaly will appear when the first-order corrections proportional to T0, are introduced.

Categorical Foundation of Quantum Mechanics and String Theory

The unification of quantum mechanics and general relativity remains the primary goal of theoretical physics, with string theory appearing as the only plausible unifying scheme. In the present work, in a search of the conceptual foundations of string theory, we analyze the relational logic developed by C. S. Peirce in the late 19th century. The Peircean logic has the mathematical structure of a category with the relation Rij among two individual terms Si and Sj, serving as an arrow (or morphism). We introduce a realization of the corresponding categorical algebra of compositions, which naturally gives rise to the fundamental quantum laws, thus indicating category theory as the foundation of quantum mechanics. The same relational algebra generates a number of group structures, among them W∞. The group W∞ is embodied and realized by the matrix models, themselves closely linked with string theory. It is suggested that relational logic and in general category theory may provide a new paradigm, within which to ...

Production of colored weak bosons at the pp collider

Abstract We adopt the hypothesis that the weak bosons are composite particles made out of consituents (haplons), which carry a new quantum number (hypercolor), but also ordinary color. Assuming that the haplons are color triplets, we expect color octet partners (W 8 ) of the weak bosons in the mass range 120–180 GeV. We study the production of W 8 at the p p collider and their decay signatures. We examine the possibility that the colored weak bosons might be at the origin of the unconventional events, recently observed at the p p collider.

Manifestations of extra dimensions in a neutrino telescope

Theories with large extra dimensions provide the possibility that a flavor neutrino, localized in a 3+1 brane, can mix with a singlet neutrino living in the bulk. This mixing leads to unconventional patterns of neutrino matter oscillations and we examine in details how these oscillations depend upon two parameters: the brane-bulk coupling

Random magnetic fields in the sun and solar neutrinos

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Signatures of TeV scale gravity in high-energy collisions

and the effective mass