International Journal of Modern Physics A

We give an overview of the present status of knowledge of the production of J/ψ, ψ′ and ϒ in high-energy hadron collisions. We first present two early models, namely the Color-Singlet Model (CSM) and the Color-Evaporation Model (CEM). The first is the natural application of pQCD to quarkonium production and has been shown to fail dramatically to describe experimental data, the second is its phenomenological counterpart and was introduced in the spirit of the quark–hadron duality in the late 1970's. Then, we expose the most recent experimental measurements of J/ψ, ψ′ and ϒ prompt and direct production at nonzero p_T from two high-energy hadron colliders, the Tevatron and RHIC. In a third part, we review six contemporary models describing J/ψ, ψ′ and ϒ production at nonzero p_T.

The nonrelativistic version of the multitemporal quantization scheme of relativistic particles in a family of noninertial frames (see Ref. 1) is defined. At the classical level the description of a family of nonrigid noninertial frames, containing the standard rigidly linear accelerated and rotating ones, is given in the framework of parametrized Galilei theories. Then the multitemporal quantization, in which the gauge variables, describing the noninertial effects, are not quantized but considered as c-number generalized times, is applied to nonrelativistic particles. It is shown that with a suitable ordering there is unitary evolution in all times and that, after the separation of the center-of-mass, it is still possible to identify the inertial bound states. The few existing results of quantization in rigid noninertial frames are recovered as special cases.

We have constructed a heavy baryon effective field theory with photon as an external field in accordance with the symmetry requirements similar to the heavy quark effective field theory. By treating the heavy baryon and antibaryon equally on the same footing in the effective field theory, we have calculated the spin polarizabilities γ_i, i = 1,…,4 of the nucleon at third order and at fourth-order of the spin-dependent Compton scattering. At leading order (LO), our results agree with the corresponding results of the heavy baryon chiral perturbation theory, at the next-to-leading order (NLO) the results show a large correction to the ones in the heavy baryon chiral perturbation theory due to baryon–antibaryon coupling terms. The low-energy theorem is satisfied both at LO and at NLO. The contributions arising from the heavy baryon–antibaryon vertex were found to be significant and the results of the polarizabilities obtained from our theory is much closer to the experimental data.

We explicitly show that, in a system with T-duality symmetry, the configuration space volume degrees of freedom may hide on the surface boundary of the region of accessible states with energy lower than a fixed value. This means that, when taking the decompactification limit (big volume limit), a number of accessible states proportional to the volume is recovered even if no volume dependence appears when energy is high enough. All this behavior is contained in the exact way of computing sums by making integrals. We will also show how the decompactification limit for the gas of strings can be defined from a microcanonical description at finite volume.

A recently proposed strictly phenomenological static quark–antiquark potential belonging to the generality V(r) = -Ar^-α + κr^β + V₀ is tested with heavy quarkonia in the context of the shifted large N-expansion method. This nonrelativistic potential model fits the spin-averaged mass spectra of the , and quarkonia within a few MeV and also the five experimentally known leptonic decay widths of the and vector states. Further, we compute the hyperfine splittings of the bottomonium spectrum as well as the fine and hyperfine splittings of the charmonium spectrum. We give predictions for not yet observed B_c splittings. The model is then used to predict the masses of the remaining quarkonia and the leptonic decay widths of the two pseudoscalar states. Our results are compared with other models to gauge the reliability of the predictions and point out differences.

Recently, Ribault and Teschner pointed out the existence of a one-to-one correspondence between N-point correlation functions for the SL(2,ℂ)_k/SU(2) WZNW model on the sphere and certain set of 2N-2-point correlation functions in Liouville field theory. This result is based on a seminal work by Stoyanovsky. Here, we discuss the implications of this correspondence focusing on its application to string theory on curved backgrounds. For instance, we analyze how the divergences corresponding to worldsheet instantons in AdS₃ can be understood as arising from the insertion of the dual screening operator in the Liouville theory side. We also study the pole structure of N-point functions in the 2D Euclidean black hole and its holographic meaning in terms of the Little String Theory. This enables us to interpret the correspondence between CFT's as encoding a LSZ-type reduction procedure. Furthermore, we discuss the scattering amplitudes violating the winding number conservation in those backgrounds and provide a formula connecting such amplitudes with observables in Liouville field theory. Finally, we study the WZNW correlation functions in the limit k → 0 and show that, at the point k = 0, the Stoyanovsky–Ribault–Teschner dictionary turns out to be in agreement with the FZZ conjecture at a particular point of the space of parameters where the Liouville central charge becomes c_L = -2. This result makes contact with recent studies on the dynamical tachyon condensation in closed string theory.

We present a simple higher dimensional FRW-type of model where the acceleration is apparently caused by the presence of the extra dimensions. Assuming an ansatz in the form of the deceleration parameter, we get a class of solutions some of which shows the desirable feature of dimensional reduction as well as reasonably good physical properties of matter. Interestingly we do not have to invoke an extraneous scalar field or a cosmological constant to account for this acceleration. One argues that the terms containing the higher dimensional metric coefficients produces an extra negative pressure that apparently drives the inflation of the 4D space with an accelerating phase. It is further found that in line with the physical requirements our model admits of a decelerating phase in the early era along with an accelerating phase at present. Further the models asymptotically mimic a steady-state-type of universe although it starts from a big-bang-type of singularity. Correspondence to Wesson's induced matter theory is also briefly discussed and, in line with it, it is argued that the terms containing the higher dimensional metric coefficients apparently creates a negative pressure which drives the inflation of the 3-space with an accelerating phase.

Electroweak precision data have been extensively used to constrain models containing physics beyond that of the Standard Model (SM). When the model contains Higgs scalars in representations other than singlets or doublets, and hence ρ≠1 at tree-level, a correct renormalization scheme requires more inputs than the three commonly used for the SM case. In such cases, the one-loop electroweak results cannot be split into a SM contribution plus a piece which vanishes as the scale of new physics becomes much larger than M_W. We illustrate our results by presenting the dependence of M_W on the top-quark mass in a model with a Higgs triplet and in the SU(2)_L × SU(2)_R left–right symmetric model. In these models, the allowed range for the lightest neutral Higgs mass can be as large as a few TeV.

In this paper, using the apparatus of the Clifford bundle formalism, we show how straightforwardly solve in Minkowski space–time the Dirac–Hestenes equation — which is an appropriate representative in the Clifford bundle of differential forms of the usual Dirac equation — by separation of variables for the case of a potential having spherical symmetry in the Cartesian and spherical gauges. We show that, contrary to what is expected at a first sight, the solution of the Dirac–Hestenes equation in both gauges has exactly the same mathematical difficulty.

The cross-couplings among several Weyl gravitons (described in the free limit by a sum of linearized Weyl actions) in the presence of a scalar field are studied with the help of the deformation theory based on local BRST cohomology. Under the hypotheses of locality, smoothness of the interactions in the coupling constant, Poincaré invariance, (background) Lorentz invariance, and the preservation of the number of derivatives on each field, together with the supplementary assumption that the internal metric defined by the sum of Weyl Lagrangians is positively defined, we prove that there are no consistent cross-interactions among different Weyl gravitons in the presence of a scalar field. The couplings of a single Weyl graviton to a scalar field are also discussed.

The asymptotic iteration method is used for Dirac and Klein–Gordon equations with a linear scalar potential to obtain the relativistic eigenenergies. A parameter, ς = 0, 1, is introduced in such a way that one can obtain Klein–Gordon bound states from Dirac bound states. It is shown that this method asymptotically gives accurate results for both Dirac and Klein–Gordon equations.

We extend the Shirafuji model for massless particles with primary space–time coordinates and composite four-momenta to a model for massive particles with spin and electric charge. The primary variables in the model are the space–time four-vector, four scalars describing spin and charge degrees of freedom as well as a pair of Weyl spinors. The geometric description proposed in this paper provides an intermediate step between the free purely twistorial model in two-twistor space in which both space–time and four-momenta vectors are composite, and the standard particle model, where both space–time and four-momenta vectors are elementary. We quantize the model and find explicitly the first-quantized wave functions describing relativistic particles with mass, spin and electric charge. The space–time coordinates in the model are not commutative; this leads to a wave function that depends only on one covariant projection of the space–time four-vector (covariantized time coordinate) defining plane wave solutions.

Invariant (nonplanar) anomaly of noncommutative QED is reexamined in this paper. It is found that just as in ordinary gauge theory UV regularization is needed to discover anomalies, in noncommutative case, in addition, an IR regularization is also required to exhibit the existence of invariant anomaly. Thus resolving the controversy in the value of invariant anomaly, an expression for the unintegrated anomaly is found. Schwinger terms of the current algebra of the theory are derived.

In this paper, we study and construct a set of Witten indexes for K, where K is any n-dimensional knot in Sⁿ⁺² and n is any natural number. We form a supersymmetric quantum system for K by, first, constructing a set of functional spaces (spaces of fermionic (resp. bosonic) states) and a set of operators (supersymmetric infinitesimal transformations) in an explicit way. Our Witten indexes are topological invariant and they are nonzero in general. These indexes are zero if K is equivalent to a trivial knot. Besides, our Witten indexes restrict to the Alexander polynomials of n-knots, and one of the Alexander polynomials of K is nontrivial if any of the Witten indexes is nonzero. Our indexes are related to homology with twisted coefficients. Roughly speaking, these indexes posseses path-integral representation in the usual manner of supersymmetric theory.

The latest measurement of the K_S→γγ branching ratio clearly shows an enhancement over the current theoretical prediction. As in other K and B meson decays, this invites to consider the possibility of the contribution of new physics. We study a particular form of the latter, which may be refered to as manifest mirror symmetry. The experimental data are described using previously determined values for the mixing angles of the admixtures of mirror matter in ordinary hadrons and by assuming that for π⁰, η, η′ → γγ, the mirror decay amplitudes have the same magnitudes as their ordinary counterparts.