International Journal of Modern Physics A

We identify a class of perturbatively computable measures of interjet energy flow, which can be associated with well-defined color flow at short distances. As an illustration, we calculate correlations between event shapes and the flow of energy, Q_Ω, into an interjet angular region, Ω, in high-energy two-jet e⁺e^--annihilation events. Laplace transforms with respect to the event shapes suppress states with radiation at intermediate energy scales, so that we may compute systematically logarithms of interjet energy flow. This method provides a set of predictions on energy radiated between jets, as a function of event shape and of the choice of the region Ω in which the energy is measured. Non-global logarithms appear as corrections. We apply our method to a continuous class of event shapes.

The existence of time machines, understood as space–time constructions exhibiting physically realised closed timelike curves (CTC's), would raise fundamental problems with causality and challenge our current understanding of classical and quantum theories of gravity. In this paper, we investigate three proposals for time machines which share some common features: cosmic strings in relative motion, where the conical space–time appears to allow CTC's; colliding gravitational shock waves, which in Aichelburg–Sexl coordinates imply discontinuous geodesics; and the superluminal propagation of light in gravitational radiation metrics in a modified electrodynamics featuring violations of the strong equivalence principle. While we show that ultimately none of these constructions creates a working time machine, their study illustrates the subtle levels at which causal self-consistency imposes itself, and we consider what intuition can be drawn from these examples for future theories.

We study the geometric aspects of two exotic bialgebras S03 and S14 introduced in math.QA/0206053. These bialgebras are obtained by the Faddeev–Reshetikhin–Takhtajan RTT prescription with non-triangular R-matrices which are denoted R₀₃ and R₁₄ in the classification of Hietarinta, and they are not deformations of either GL(2) or GL(1|1). We give the spectral decomposition which involves two, respectively, three, projectors. These projectors are then used to provide the baxterization procedure with one, respectively, two, parameters. Further, the projectors are used to construct the noncommutative planes together with the corresponding differentials following the Wess–Zumino prescription. In all these constructions there appear nonstandard features which are noted. Such features show the importance of systematic study of all bialgebras of four generators.

In the framework of potential models for heavy quarkonium, we compute the mass spectrum of the bottom-charmed B_c meson system and spin-dependent splittings from the Schrödinger equation using the shifted-large-N expansion technique. The masses of the lightest vector and pseudoscalar B_c states as well as the higher states below the threshold are estimated. Our predicted result for the ground state energy is MeV and are generally in exact agreement with earlier calculations. Calculations of the Schrödinger energy eigenvalues are carried out up to the third order of the energy series. The parameters of each potential are adjusted to obtain best agreement with the experimental spin-averaged data (SAD). Our findings are compared with the observed data and with the numerical results obtained by other numerical methods.

We search for a bosonic (nonsupersymmetric) string/gauge theory correspondence by using the ten-dimensional IIB and 0B strings as a guide. Our construction is based on the low-energy bosonic string effective action modified by an extra form flux. We prove that the closed string tachyon can be stabilized in this context, when the AdS scalem L does not exceed a certain critical value, L<L_c. The extra form may be nonperturbatively generated as a soliton from 3-string junctions, similarly to the known nonperturbative (Jackiw–Rebbi–'t Hooft–Hasenfratz) mechanism in gauge theories, as was recently argued by David, Minwalla and Núñez. We find a stable AdS₁₃×S¹³ solution that implies the existence of a 12-dimensional AdS-boundary conformal field theory with the SO(14) global symmetry in the large N't Hooft limit, which is similar to the recently proposed bosonic M-theory of Horowitz and Susskind. Taking the proposed bosonic AdS/CFT correspondence for granted, we generalize it to finite temperature. The corresponding "glueball" masses in higher space–time dimensions are calculated from the dilaton wave equation in the AdS black hole background.

The surface energy for a conformally flat space–time which represents the Hawking wormhole in spherical (static) Rindler coordinates is computed using the Hawking–Hunter formalism for nonasymptotically flat space–times. The physical gravitational Hamiltonian is proportional to the Rindler acceleration g of the hyperbolic observer and is finite on the event horizon ξ=b (b — the Planck length, ξ — the Minkowski interval). The corresponding temperature of the system of particles associated to the massless scalar field Ψ=1-b²/ξ², coupled conformally to Einstein's equations, is given by the Davies–Unruh temperature up to a constant factor of order unity.

The universe exhibits two striking manifestations, (a) immense complexity and (b) an astonishingly high scale-free precision. Since a cryptographic system based on the modular arithmetic of a finite field can provide a mathematical structure matching these two cardinal characteristics, it is natural to evaluate the theoretical possibilities of a cryptographic analysis of physical phenomena. The organization of the particle mass scale provides a particularly suitable test of this idea, since the cryptographic approach also has the inherent feature that divergences are fully barred, thereby eliminating the need for ad hoc procedures of renormalization. This article (1) shows how such a cryptographic concept can be implemented and (2) demonstrates its surprising ability to synthesize the description of a broad range of phenomena through the development of an interlocking set of quantitative findings. It is found that a cryptographic theoretical framework based solely on two physically anchored parameters, a modulus P_α and a corresponding primitive root g_α, can simultaneously achieve six goals. Specifically, it (α) unites the concepts of mass and space, (β) organizes the physical mass scale in a group structure, (γ) produces a quantitative concordance of findings linking the cosmic and micro-scales that includes values for the fine structure constant α and the unified strong-electroweak coupling constant α*, (δ) respectively gives prospective magnitudes of 0.808 meV and 27.68 meV for the rest masses m_νe and m_νμ of the electron (ν_e) and muon (ν_μ) neutrinos, (∊) specifies a symmetry condition that yields an exact predicted value for the Higgs particle mass that lies above 10¹⁸ GeV, and (ζ) enables the formulation of a direct physical connection between the anomalous flavor (ν_e/ν_μ) transforming propagation of solar neutrinos and the existence of a positive cosmological constant Λ. These results are uniformly in agreement with all corresponding observational data.

The Casimir forces on two parallel plates in conformally flat de Sitter background due to conformally coupled massless scalar field satisfying mixed boundary conditions on the plates is investigated. In the general case of mixed boundary conditions formulae are derived for the vacuum expectation values of the energy–momentum tensor and vacuum forces acting on boundaries. Different cosmological constants are assumed for the space between and outside of the plates to have general results applicable to the case of domain wall formations in the early universe.

We initiate the study of Brane Gas Cosmology (BGC) on manifolds with nontrivial holonomy. Such compactifications are required within the context of superstring theory in order to make connections with realistic particle physics. We study the dynamics of brane gases constructed from various string theories on background spaces having a K3 submanifold. The K3 compactifications provide a stepping stone for generalizing the model to the case of a full Calabi–Yau threefold. Duality symmetries are discussed within a cosmological context. Using a duality, we arrive at an N=2 theory in four dimensions compactified on a Calabi–Yau manifold with SU(3) holonomy. We argue that the Brane Gas model compactified on such spaces maintains the successes of the trivial toroidal compactification while greatly enhancing its connection to particle physics. The initial state of the universe is taken to be a small, hot and dense gas of p-branes near thermal equilibrium. The universe has no initial singularity and the dynamics of string winding modes allow three spatial dimensions to grow large, providing a possible solution to the dimensionality problem of string theory.

We consider solitonic solutions of coupled scalar systems, whose Lagrangian has a potential term (quasisupersymmetric potential) consisting of the square of derivative of a superpotential. The most important feature of such a theory is that among soliton masses there holds a Ritz-like combination rule (e.g. M₁₂+M₂₃=M₁₃), instead of the inequality (M₁₂+M₂₃<M₁₃) which is a stability relation generally seen in N=2 supersymmetric theory. The promotion from N=1 to N=2 theory is considered.