International Journal of Modern Physics A

We discuss possible signals for very high energy neutrinos and the astrophysics and particle physics phenomena that can be probed by measuring such signals.

A brief overview is given of recent developments and fresh ideas at the intersection of - and/or -symmetric quantum mechanics with supersymmetric quantum mechanics (SUSY QM). Within the framework of the resulting supersymmetric version of -symmetric quantum mechanics we study the consequences of the assumption that the "charge" operator is represented in a differential-operator form of the second or higher order. Besides the freedom allowed by the Hermiticity constraint for the operator , encouraging results are obtained in the second-order case. In particular, the integrability of intertwining relations proves to match the closure of our nonlinear (viz., polynomial) SUSY algebra. In a particular illustration, our form of -symmetric SUSY QM leads to a new class of non-Hermitian polynomial oscillators with real spectrum which turn out to be -asymmetric.

We present a nonperturbative study of the (1+1)-dimensional massless Thirring model by using path integral methods. The regularization ambiguities — coming from the computation of the fermionic determinant — allow to find new solution types for the model. At quantum level the Ward identity for the 1PI 2-point function for the fermionic current separates such solutions in two phases or sectors, the first one has a local gauge symmetry that is implemented at quantum level and the other one without this symmetry. The symmetric phase is a new solution which is unrelated to the previous studies of the model and, in the nonsymmetric phase there are solutions that for some values of the ambiguity parameter are related to well-known solutions of the model. We construct the Schwinger–Dyson equations and the Ward identities. We make a detailed analysis of their UV divergence structure and, after, we perform a nonperturbative regularization and renormalization of the model.

The contrasting nature of the p_T-spectra measured in deuteron (D)–gold (Au) and gold (Au)–gold (Au) collisions, both performed at RHIC-BNL at , is now considered to be a very stimulating and hot topic in the domain of high energy nuclear physics. In continuation of our efforts to understand the measured data in high energy nuclear collisions in a somewhat nonstandard and alternative way, called the Combinational Approach (CA), we try here first to understand and reproduce the latest observations on deuteron–gold collisions at at mid-rapidity and some other rapidity regions with the same. Besides, (i) we also bring out the features of contrast for nuclear modification factor (NMF) in Au Au collisions at ; (ii) for cross-checking of the present and previous results we also obtain the hadronic ratios measured for only the Au Au collisions at , as the data on the similar ratios for D Au interactions are not yet available. Finally, we point out the implications of the approach in terms of both data-interpretation and physical insights.

In this paper, using a Hopf-algebraic method, we construct deformed Poincaré SUSY algebra in terms of twisted (Hopf) algebra. By adapting this twist deformed super-Poincaré algebra as our fundamental symmetry, we can see the consistency between the algebra and non(anti)commutative relation among (super)coordinates and interpret that symmetry of non(anti)commutative QFT is in fact twisted one. The key point is validity of our new twist element that guarantees non(anti)commutativity of space. It is checked in this paper for case. We also comment on the possibility of noncommutative central charge coordinate. Finally, because our twist operation does not break the original algebra, we can claim that (twisted) SUSY is not broken in contrast to the string inspired SUSY in non(anti)commutative superspace.

An introduction to Yangians and their representations, to Yangian symmetry in 1+1D integrable (bulk) field theory, and to the effect of a boundary on this symmetry.

The semiclassical corrections to the Cardy–Verlinde entropy of a five-dimensional Schwarzschild de-Sitter black hole (SdS₅) are explicitly evaluated. These corrections are considered within the context of KKW analysis and arise as a result of the self-gravitation effect. In addition, a four-dimensional spacelike brane is considered as the boundary of the SdS₅ bulk background. It is already known that the induced geometry of the brane is exactly given by that of a radiation-dominated FRW universe. By exploiting the CFT/FRW-cosmology relation, we derive the self-gravitational corrections to the first Friedmann-like equation which is the equation of the brane motion. The additional term that arises due to the semiclassical analysis can be viewed as stiff matter where the self-gravitational corrections act as the source for it. This result is contrary to standard analysis that regards the charge of SdS₅ bulk black hole as the source for stiff matter. Furthermore, we rewrite the Friedmann-like equation in such a way that it represents the conservation equation of energy of a point particle moving in a one-dimensional effective potential. The self-gravitational corrections to the effective potential and, consequently, to the point particle's motion are obtained. A short analysis on the asymptotic behavior of the four-dimensional brane is presented.

The integrated Sachs–Wolfe (ISW) effect in a Λ dominated universe can be an important factor in the evolution of cosmic microwave background fluctuations. With the inclusion of cosmological constant we present the complete analytic solution of the covariant linear perturbations of the Einstein equations in the Newtonian gauge, in the case of a spatially flat (K = 0), Friedman–Robertson–Walker (FRW) universe, filled with pressureless ideal fluid. We use the analytic time dependence of the perturbation potentials to derive the anisotropy power spectrum of the late ISW effect. We choose the scale invariant Harrison–Zeldovich spectrum for obtaining the C_ℓ momenta and show the agreement of our results with earlier, numeric calculations.

The feasibility of using lattice chiral fermions which are free of O(a) errors for both the heavy and light quarks is examined. The fact that the effective quark propagators in these fermions have the same form as that in the continuum with the quark mass being only an additive parameter to a chirally symmetric anti-Hermitian Dirac operator is highlighted. This implies that there is no distinction between the heavy and light quarks and no mass dependent tuning of the action or operators as long as the discretization error O(m²a²) is negligible. Using the overlap fermion, we find that the O(m²a²) (and O(ma²)) errors in the dispersion relations of the pseudoscalar and vector mesons and the renormalization of the axial-vector current and scalar density are small. This suggests that the applicable range of ma may be extended to ~0.56 with only 5% error, which is a factor of ~2.4 larger than the corresponding range of the improved Wilson action. We show that the generalized Gell–Mann–Oakes–Renner relation with unequal masses can be utilized to determine the finite ma corrections in the renormalization of the matrix elements for the heavy-light decay constants and semileptonic decay constants of the B/D meson.

Constraints are obtained on the mass of additional, family-nonuniversal W′ bosons, suggested by the Sp(6)_L⊗U(1)_Y model, from high-energy collider data. A lower bound is obtained on W′ mass, M_W′ ≳ 626 GeV. We studied the Drell–Yan production and corresponding decay signatures of the W′ bosons at the CERN Large Hadron Collider (LHC) and discussed how to distinguish the model by examining the couplings of W′ to fermions through its leptonic decay modes.

We extend the Gross–Perry–Yaffe approach of hot flat space instability to Minkowski space. This is done by a saddle point approximation of the partition function in a Schwarzschild wormhole background which is coincident with an eternal black hole. The appearance of an instability in the whole manifold is here interpreted as a black hole pair creation.

In the context of relativistic quantum mechanics, we obtain a nonlinear first order differential equation for the energy as a function of the coupling constant of a central potential. This differential equation is only exact for power law and logarithmic potentials in the massless limit. For other potentials, we discuss under which conditions the differential equation yields rigorous upper and lower limits on the value of energy levels. These results are applied to the Cornell potential used in meson spectroscopy. We also show that the method applies to noncentral potentials.