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We investigate the quasi-integrability properties of various deformations of the Korteweg–de Vries (KdV) equation, depending on two parameters ε1 and ε2, which include among them the regularized long-wave (RLW) and modified regularized long-wave (mRLW) equations. We show, using analytical and numerical methods, that the charges, constructed from a deformation of the zero curvature equation for the KdV equation, are asymptotically conserved for various values of the deformation parameters. By this we mean that, despite the fact that the charges do vary in time during the scattering of solitons, they return after the scattering to the same values they had before it. This property was tested numerically for the scattering of two and three solitons, and analytically for the scattering of two solitons in the mRLW theory (ε2=ε1=1). In addition we show that for any values of ε1 and ε2 the Hirota method leads to analytical one-soliton solutions of our deformed equation but for ε1≠1 such solutions have the dispersion relation which depends on the parameter ε1. We also discuss some properties of soliton-radiation interactions seen in some of our simulations.

An attempt is made to present the influence of the scalar unparticle on some scattering processes in the Randall–Sundum model. The contribution of the scalar unparticle on the production of Higgs–radion at high energy colliders is studied in detail. We evaluate the production cross-sections in the electron–positron (e+e−), photon–photon (γγ) and gluon–gluon (gg) collisions, which depend strongly on the collision energy s, the scaling dimension dU of the unparticle operator OU and the energy scale ΛU. Numerical evaluation shows that the cross-sections for the pair production of scalar particles are much larger than that of the associated production of the scalar particle with unparticle under the same conditions.

At the tree level, the scattering processes involving open and closed strings are described by a disk world-sheet with vertex operator insertions at the boundary and in the bulk. Such amplitudes can be decomposed as certain linear combinations of pure open string amplitudes. While previous relations have been established on the double cover (complex sphere) in this letter we derive them on the disk (upper complex half plane) allowing for different momenta of the left- and right-movers of the closed string. Formally, the computation of disk amplitudes involving both open and closed strings is reduced to considering the monodromies on the underlying string world-sheet., Comment: 18 pages, 3 figures, harvmac

In this paper we extend our analyses of the decay constant and distribution amplitude with an improved holographic wavefunction to the heavy-light pseudoscalar mesons. In the evaluations, the helicity-dependence of the holographic wavefunction is considered; and an independent mass scale parameter is employed to moderate the strong suppression induced by the heavy quark. Under the constraints from decay constants and masses of pseudoscalar mesons, the $\chi^2$-analyses for the holographic parameters exhibit a rough consistence with the results obtained by fitting the Regge trajectory. With the fitted parameters, the results for the decay constants and distribution amplitudes are presented. We then show their application in evaluating the $B_{d,s}\to D_{d,s}P$ decays, in which the power-suppressed spectator scattering and weak annihilation corrections are first estimated. Numerically, the spectator scattering and weak annihilation corrections present a negative shift of about $ 0.7\%$ on the branching fractions; while, the predictions are still larger than the experimental data. Such small negative shift confirms the estimation based on the power counting rules., Comment: 10 pages, 5 figures

The Cachazo-He-Yuan (CHY) formula for on-shell scattering amplitudes are extended off-shell. The off-shell amplitudes are M\"obius invariant, and have the same momentum poles as the on-shell amplitudes. The same technique is also used to obtain off-shell massive scalar and vector boson amplitudes., Comment: References updated. Text somewhat rewritten to better explain the contents

Starting with the Chern-Simons formulation of (2+1)-dimensional gravity we show that the gravitational interactions deform the Poincare symmetry of flat space-time to a quantum group symmetry. The relevant quantum group is the quantum double of the universal cover of the (2+1)-dimensional Lorentz group, or Lorentz double for short. We construct the Hilbert space of two gravitating particles and use the universal R-matrix of the Lorentz double to derive a general expression for the scattering cross section of gravitating particles with spin. In appropriate limits our formula reproduces the semi-classical scattering formulae found by 't Hooft, Deser, Jackiw and de Sousa Gerbert., Comment: 45 pages, amslatex

The inclusive spectra of charged particles measured at high transverse momenta ($p_T\gtrsim$2GeV/c) in proton-proton and proton-antiproton collisions in the range of center-of-mass energies $\sqrt{s}=200-7000$GeV are compared with next-to-leading order perturbative QCD calculations using seven recent sets of parton-to-hadron fragmentation functions (FFs). Accounting for the uncertainties in the scale choices and in the parton distribution functions, we find that most of the theoretical predictions tend to overpredict the measured LHC and Tevatron cross sections by up to a factor of two. We identify the currently too-hard gluon-to-hadron FFs as the probable source of the problem, and justify the need to refit the FFs using the available LHC and Tevatron data in a region of transverse momenta, $p_T\gtrsim$10GeV/c, which is supposedly free from additional non-perturbative contributions and where the scale uncertainty is only modest., Comment: Updated version to appear in Nuclear Physics B

We study the validity of a relation by Drell, Levy and Yan (DLY) connecting the deep inelastic structure (DIS) functions and the single-particle fragmentation functions in e^+e^- annihilation which are defined in the spacelike (q^2 0) regions respectively. Here q denotes the momentum of the virtual photon exchanged in the deep inelastic scattering process or the annihilation process. An extension of the DLY-relation, which originally was only derived in the scaling parton model, to all orders in QCD leads to a connection between the two evolution kernels determining the q^2-dependence of the DIS structure functions and the fragmentation functions respectively. In relation to this we derive the transformation relations between the space-and time-like splitting functions up to next-to-leading order (NLO) and the coefficient functions up to NNLO both for unpolarized and polarized scattering. It is shown that the evolution kernels describing the combined singlet evolution for the structure functions F_2(x,Q^2), F_L(x,Q^2) where Q^2=|q^2| or $F_2(x,Q^2), \partial F_2(x,Q^2)/\partial \ln(Q^2)$ and the corresponding fragmentation functions satisfy the DLY relation up to next-to-leading order. We also comment on a relation proposed by Gribov and Lipatov.

Shadowing in inelastic lepton-deuteron scattering is analysed using the double interaction formalism where we relate shadowing to inclusive diffractive processes. Both the vector meson and parton contributions are considered for low and high Q 2 values including QCD corrections with parton recombination for high Q 2 . These Q 2 values were chosen to correspond to existing experimental data and to the possible HERA measurements. Detailed discussion of various shadowing mechanisms is given. As expected the shadowing effects are found to be very small, less then 2% or so, in agreement with the recent precise measurements performed by the New Muon Collaboration. The contribution of shadowing terms to the Gottfried sum from the region x > 0.004 and for Q 2 = 4 GeV 2 is estimated to be equal to −0.025.

We present an analysis of pp and p p elastic scattering in terms of various exchanges. Three-gluon exchange dominates at large t , and single-pomeron exchange at small t . The dip seen in high-energy pp scattering is provided by the interference of both of these with double-pomeron exchange. We predict that this dip will not be found in high-energy p p scattering. The dip that is seen in low-energy p p scattering is the result of the additional presence of reggeon-pomeron exchange.

We present results on the experimental study of inelastic charged-current antineutrino-nucleon scattering in the energy range of 10–200 GeV. The data sample, consisting of about 6500 antineutrino-induced events, was obtained in the Fermilab 15 ft bubble chamber filled with a heavy neon-hydrogen mixture. The differential cross sections for ¯νμN interactions are presented in terms of scaling variables x and y. The structure functions F2ν and xF3¯ν have been evaluated as functions of x and E¯ν. A deviation from the scaling hypothesis, similar to those found in other experiments on inelastic lepton-nucleon scattering, has been observed. The data are interpreted in the framework of the quark-parton model. Quark and antiquark distributions and their energy dependences are presented.

The qualitative predictions of quantum chromodynamics for high-energy hadron-nucleus scattering are expounded. Inclusive particle distributions from hadron interactions on proton and aluminum targets are compared to the theoretical expectations for both low and high transverse momentum ( p ⊥ ) scattering. In the latter case, we present data on the nuclear effects in the fragmentation of both the beam and scattered partons. At low p ⊥ , we show evidence for short-range correlations between the final particles produced in hadron-aluminum collisions.

New, strong restrictions on the pion charge radius and pion electromagnetic form factor F ( t ) in the spacelike region, as well as on the asymptotic ππ scattering, are derived using the Chou-Yang model for spacelike F ( t ) combined with experimental data on | F ( t )| in the timelike region and with rather weak analyticity assumptions for the pion form factor.

A parton model for diffractive dissociation processes is proposed. It is assumed that the elastic diffractive scattering of partons off the target leads to diffractive excitation of the incident particle and/or the diffractive production of new particles. A prescription for calculating transition matrix elements is given and illustrated by several examples of strong and electromagnetic processes. Relation to: (a) one-particle exchange models, (b) vector dominance model, (c) Chou and Yang model and (d) QED calculations of Cheng and Wu is discussed. These models turn out to be special cases of our model.

The connection between the model of opaque nucleus and that of Glauber for the case of the deuteron-nucleus scattering is studied. It is shown that the contribution, to the total cross section, of the nucleus virtual excitations induced by the double scattering processes in which all the nucleons of the deuteron take part, is negligible when the nucleus becomes absolutely opaque.

A one-boson-exchange (OBE) model of baryon-baryon interaction is developed. The forces are assumed to be generated by the exchange of 0−, 1− octets and a tentatively assumed 0+ octet simulating two-boson-exchange effects. To obtain the relevant coupling constants and masses of 0+ particles the Hamada-Johnston N-N potential is fitted by OBE potential. This, together with SU(3) symmetry assumed for the couplings, determines completely the Λ-N potential. The resulting potential has appeared too strong but slight adjustment of the coupling constant of the 0+ I=0 particle gave a very good agreement with the experimental data on Λ-N scattering. We find rather strong tensor force operating in the Λ-N system and this may explain the existing discrepancy between the hypernuclear and fitted estimates of the strength of the Λ-N forces.