Proposal for chiral-boson search at LHC via their unique new signature

The resonance production of new chiral spin-1 bosons and their detection through the Drell-Yan process at the CERN LHC is considered. Quantitative evaluations of various differential cross sections of the chiral-boson production are made within the CalcHEP package. The new neutral chiral bosons can be observed as a Breit-Wigner resonance peak in the invariant-dilepton-mass distribution, as usual. However, unique new signatures of the chiral bosons exist. First, there is no Jacobian peak in the lepton transverse-momentum distribution. Second, the lepton angular distribution in the Collins—Soper frame for the high on-peak invariant masses of the lepton pairs has a peculiar “swallowtail” shape. The text was submitted by the authors in English.     

Muon pair production in very high energy nucleus-nucleus collisions

Characteristics of muon pair production in very high energy nucleus-nucleus collisions are discussed. Particular attention is given to comparing the rate of muon pairs produced from thermalized quark-gluon matter to that of pairs produced via the usual Drell-Yan mechanism. The thermal rate is at least of the same order of magnitude as the direct Drell-Yan rate and will certainly dominate whenx _F for the pair approaches 1. Beyondx _F =1 the thermal rate is also substantial. This region is particularly easily accessible in fixed target experiments.     

Compton and double-compton scattering processes at colliding electron-photon beams

Radiative corrections to the Compton scattering cross section are calculated in the leading and next-to-leading logarithmic approximations in the case of colliding high-energy photon-electron beams. Radiative corrections to the double-Compton scattering cross section in the same experimental setup are calculated in the leading logarithmic approximation. We consider the case where no pairs are created in the final state. We show that the differential cross section can be written in the form of the Drell-Yan process cross section. Numerical values of the K-factor and the leading-order distribution on the scattered electron energy fraction and scattering angle are presented.     

Quark Energy Loss and Shadowing in Nuclear Drell-Yan Process

The energy loss effect in nuclear matter is another nuclear effect apart from the nuclear effects on the parton distribution as in deep inelastic scattering process. The quark energy loss can be measured best by the nuclear dependence of the high energy nuclear Drell-Yan process. By means of three kinds of quark energy loss parameterizations given in literature and the nuclear parton distribution extracted only with lepton-nucleus deep inelastic scattering experimental data, measured Drell-Yan production cross sections are analyzed for 800 GeV proton incident on a variety of nuclear targets from FNAL E866. It is shown that our results with considering the energy loss effect are much different from those of the FNAL E866, who analyzes the experimental data with the nuclear parton distribution functions obtained by using the deep inelastic IA collisions and pA nuclear Drell-Yan data. Considering the existence of energy loss effect in Drell-Yan lepton pairs production, we suggest that the extraction of nuclear parton distribution functions should not include Drell-Yan experimental data.     

Quark Energy Loss and Shadowing in Nuclear Drell-Yan Process

The energy loss effect in nuclear matter is another nuclear effect apart from the nuclear effects on the parton distribution as in deep inelastic scattering process. The quark energy loss can be measured best by the nuclear dependence of the high energy nuclear Dre11-Yan process. By means of three kinds of quark energy loss parameterizations given in literature and the nuclear parton distribution extracted only with lepton-nucleus deep inelastic scattering experimental data, measured Dre11-Yan production cross sections are analyzed for 800 GeV proton incident on a variety of nuclear targets from FNAL E866. It is shown that our results with considering the energy loss effect are much different from those of the FNAL E866, who analyzes the experimental data with the nuclear parton distribution functions obtained by using the deep inelastic IA collisions and pA nuclear Drell-Yan data. Considering the existence of energy loss effect in Drell-Yan lepton pairs production, we suggest that the extraction of nuclear parton distribution functions shoul““““d not include Dre11-Yan experimental data.     

Massive μ pair production in a vector field theory model

We treat massive electrodynamics as a model for the production of massive μ pairs in high-energy hadronic collisions. The dominant diagrams in perturbation theory are identified and analyzed. These graphs have an eikonal structure which leads to enormous cancellations in the two-particle inclusive cross section but not in the n-particle production cross sections. Under the assumption that these cancellations are complete, a Drell-Yan structure appears in the inclusive cross section but the particles accompanying the μ pairs have a very different structure compared to the parton model. The pionization region is no longer empty of particles as in simple parton models.     

The transverse hadronic energy accompanying weak bosons

We study the hadronic transverse energy (E _T ) accompanyingZ ⁰ events in \(p\bar p\) interactions and compare our result with the observedE _T distribution in minimum bias events. We expect excess transverse energy to accompanyZ ⁰'s. This effect can also be probed experimentally using Drell-Yan lepton pairs and represents an interesting way to probe the multi-gluon structure of QCD.     

Analysis of the reaction pp → p(ππ)0 p,and the question of double pomeron exchange in high-energy production processes

A low-mass S-wave (ππ)⁰ enhancement is observed in the reaction pp → p (ππ)⁰ p at 12 and 24 GeV/c incident momentum. The mechanism for producing these low-mass pion pairs is investigated, and it is shown that double pomeron exchange can contribute at most 5% to their production cross section at 24 GeV/c.     

Impulse approximation in QCD,Parton's pT-distribution and application to deep inelastic process

The recently formulated theory of the impulse approximation in QCD is developed further. The integro-differential equation describing the evolution of the parton's distribution function is solved. The formalism is applied to compute R = σ_L/σ_T in deep inelastic electron scattering and the average transverse momentum 〈k_T〉 of the Drell-Yan pairs. The cross section formula for the latter process is significantly different from the one recently conjectured. Agreement with recent data is good in both cases.     

Measurement of single electron production up to 45 GeV/c transverse momentum at the CERN ISR

The production of single electrons of transverse momentum between 1.8 and 45 GeV/c is measured in pp collisions at √s=53 and 63 GeV. Contributions from ?,ω,?,ψ, ?, DD? and Drell-Yan pairs are deduced from measurements in the same apparatus.     

Angular distributions of Drell Yan pairs in the leading twist approximation

We compute the angular decay distribution of lepton pairs, integrated over the transverse momentum within the soft gluons resummation procedure. The deviations from the naive Drell-Yan model are found very small. Therefore, the phase space boundary region should provide a clear signal for higher twist contributions.     

Transverse-spin and transverse-momentum effects in high-energy processes

The state of the art concerning transverse-spin and transverse-momentum phenomena in hard hadronic reactions is reviewed. An account is given of single-spin and azimuthal asymmetries in semi-inclusive deep inelastic scattering, annihilation, Drell-Yan production, and hadroproduction. The ongoing experiments and the main theoretical frameworks are described in the first part of the paper. The second part is devoted to the experimental findings and their phenomenological interpretations. A brief discussion of the perspectives of future measurements is finally presented.     

Dissociation of expanding cc̄ states in heavy ion collisions

We study J/ψ suppression in AB collisions assuming that the charmonium states evolve from small, color transparent configurations. Their interaction with nucleons and nonequilibrated, secondary hadrons is simulated using the microscopic model UrQMD. The Drell-Yan lepton pair yield and the J/ψ/Drell-Yan ratio are calculated as a function of the neutral transverse energy in Pb+Pb collisions at 160 GeV and found to be in reasonable agreement with existing data.     

Hadronic colliders as probes of the proton spin structure

We perform a systematic analysis of different processes with high energy polarized proton beams: jets, direct photon, lepton pairs (Drell-Yan) andWZ production. Different sets of polarized partonic densities are used that fit EMC and SLAC polarized deep inelastic scattering data with variable amount of quark and gluon components of the proton spin. The case of the future Relativistic Heavy Ion Collider (RHIC) used as a polarized collider at a maximum energy of \(\sqrt s = 500\) GeV is analyzed in detail.     

Drell-Yan production of massive muon pairs

Cross-sections for Drell-Yan production of massive muon pairs by incident π^±, K^±, p and $\text{p}$ on an isoscalar, nuclear target are calculated.     

What can Drell-Yan data tell us about the EMC effect and nucleon parton distributions?

We show that knowledge of thex ₁ andx ₂ dependence of the ratio of Drell-Yan cross-sections measured on heavy nuclei and deuterium can give us information about the origin of the EMC effect. Conversely, we show that an understanding of the EMC effect, together with (non-ratio) Drell-Yan data, can provide us with a way of discriminating between candidates for nucleon parton distributions.     

Lepton pair production at large transverse momentum in second order QCD

The production of Drell-Yan pairs at large transverse momentum is calculated up to O(α_s²) for a non-singlet combination defined as the cross section for an incident particle minus the analogous cross section for an incident antiparticle. Analytic results are presented for all cross sections and numerical estimates are given at various energies of experimental interest.