Heavy flavour multiplicities at very high energies

We calculate the total multiplicity of heavy flavours in e⁺e^? annihilation at very high energies in the framework of QCD. The problem is dominated by the soft limit of the perturbative expansion and we develop suitable techniques to resum to all orders the leading double logarithmic terms. The results indicate at very high energy a growth of multiplicity faster than any power of log. We find an interesting asymptotic factorization of energy dependence and flavour mass dependence of multiplicities.     

Production of secondaries in relativistic nuclei collisions at high energies

Using the multiple-scattering theory and quark-gluon string model, the averaged and central collisions between high-energy nuclei are studied. Production of light flavour hadrons as well as charmed and beauty mesons and baryons is considered. We present predictions for mean multiplicities of secondaries, inclusive spectra and distributions over multiplicity for the case of Au?Au collisions with energy 100 GeV per nucleon in every beam.     

Impact picture in the coulomb interference region at high energies

We present the predictions on pp̄ elastic differential cross sections in the Coulomb interface region for energies 0.546 to 2.0 TeV on the basis of the impact picture.     

Transverse mass distributions in central heavy-ion collisions at high energies

The transverse mass spectra of protons, pions, kaons, Lambda and Antilambda produced in cen- tral nucleus-nucleus collisions at high energies are described by using one-temperature and two-temperature emission pictures. The calculated results are compared and found to be in good agreement with the experimen- tal data of the E895, E866 and E917 Collaborations measured in central Au-Au collisions at the Alternating Gradient Synchrotron (AGS) energies and the NA49 Collaboration measured in central Pb-Pb collisions at the Super Proton Synchrotron (SPS) energies. It is demonstrated that the transverse mass distributions of protons, kaons, Lambda and Antilambda, except for Lambda hyperons produced in central Pb-Pb collisions at 158 A GeV, can be described by using the one-temperature emission picture, and for pions, we need to use the two-temperature emission picture.     

Transverse mass distributions in central heavy-ion collisions at high energies

The transverse mass spectra of protons, pions, kaons, Lambda and Antilambda produced in central nucleus-nucleus collisions at high energies are described by using one-temperature and two-temperature emission pictures. The calculated results are compared and found to be in good agreement with the experimental data of the E895, E866 and E917 Collaborations measured in central Au-Au collisions at the Alternating Gradient Synchrotron (AGS) energies and the NA49 Collaboration measured in central Pb-Pb collisions at the Super Proton Synchrotron (SPS) energies. It is demonstrated that the transverse mass distributions of protons, kaons, Lambda and Antilambda, except for Lambda hyperons produced in central Pb-Pb collisions at 158 A GeV, can be described by using the one-temperature emission picture, and for pions, we need to use the two-temperature emission picture.     

On intensity interferometry at high multiplicities

Zeitschrift für Physik C Particles and Fields - We are discussing different aspects of single-and multiparticle spectra produced from a source with very high particle density in phase space....     

Proton distributions in the target fragmentation region in proton-nucleus and nucleus-nucleus collisions at high energies

We present measurements of the rapidity and transverse-momentum distributions of the protons emitted in S+W, O+W, andp+W reactions at 200 GeV/A around the target rapidity (y=1). The rapidity density rises linearly with the transverse energy for all three systems, but the slope forp+W is much steeper than for O+W and S+W. The rapidity density forp+W is much higher than predicted by summing single nucleonnucleon collisions without any nuclear effects, indicating substantial rescattering of the produced particles. The predictions of the VENUS 3 model, including rescattering, show reasonable agreement with the data for all three systems. We do not have evidence for a strong collective flow of the outgoing particles.     

Thermodynamics at high energies

A new thermodynamics, applicable to cosmic ray showers and high-energy physics, is developed. Although all density expressions are unaltered, their global forms are modified due to the new dependence between the volume and the temperature. This occurs in bound systems where the number of particles, instead of being an increasing function of the temperature, is a decreasing one. That certain global expressions for the entropy turn out to be convex functions of the energy necessitates their reinterpretation as the reduction in entropy caused by the volume-temperature constraint. The continuous distribution for the production of hadrons with energies greater than a given amount is shown to correspond to the fact that discrete particle fluctuations follow Poisson's law.     

Midrapidity production of secondaries in pp collisions at RHIC and LHC energies in the quark–gluon string model

We consider the phenomenological implications of the assumption that baryons are systems of three quarks connected through a gluon string junction. The transfer of baryon number in rapidity space due to the string junction propagation is considered in detail. At high energies this process leads to a significant effect on the net baryon production in hN collisions at midrapidities. The numerical results for midrapidity inclusive densities of different secondaries in the framework of the quark–gluon string model are in reasonable agreement with the experimental data. One universal value, λ≃0.25, for the strangeness suppression parameter correctly describes the yield ratios of Λ/p, Ξ/Λ, and Ω/Ξ. The predictions for pp collisions at LHC energies are also presented. PACS 25.75.Dw     

Pomeron and odderon at high energies

One of the crucial questions which high energy elastic data ought to be able to answer is: is the odderon contribution really necessary? Using a model with mildly energy dependent form factors as input and performing full eikonalization before we compare with the data, the answer that we find from a careful examination of the various options is that the odderon is indeed necessary if: 1) we trust the ISRpp data to be precise enough that their comparison with the collider data onpc \(\bar p\) is meaningful, 2) we demandquantitative (i.e. not justqualitative) agreement between theory and experiment and 3) we account for the large |t| data.     

Gamma-ray bursts at high and very high energies

Gamma-Ray Bursts (GRBs) are extra-galactic and extremely energetic transient emissions of gamma rays, which are thought to be associated with the death of massive stars or the merger of compact objects in binary systems. Their huge luminosities involve the presence of a newborn stellar-mass black hole emitting a relativistic collimated outflow, which accelerates particles and produces non-thermal emissions from the radio domain to the highest energies. In this article, I review recent progresses in the understanding of GRB jet physics above 100 MeV, based on Fermi observations of bright GRBs. I discuss the physical implications of these observations and their impact on GRB modeling, and I present some prospects for GRB observation at very high energies in the near future.     

High-energy interactions in the region of extreme multiplicities

Physics of Atomic Nuclei - Hadron and nuclear interactions at high energies in the region of extreme multiplicities (much higher than mean multiplicities) are reviewed. Collective phenomena such as...     

Particle composition at high transverse momenta in p-p-collisions in the central region at the CERN ISR

Preliminary measurements have been made at centre of mass energies √s = 31 and 44 GeV of the π, K and p production ratios at 90° for p_T between 2.0 and 3.5 GeV/c. The (K+p)/π ratio is given down to p_T = 1.4 GeV/c. No strong energy dependence is observed for these transverse momenta.     

Intermittency regions at high energies

We investigate the non-statistical multiplicity fluctuations (intermittency) of hadrons produced in high-energy collisions. Within the framework of the two-mechanism model, we determine the limits of the intermittent regions. We observe that these regions decrease in extent with increasing total energy $\sqrt s$ . In addition, we determine the value of the exponent from the universal scaling law (discovered recently by R. Hwa et al.). The value of this exponent is close to corresponding experimental data.     

Nucleus-nucleus collisions at high energies

Nucleus-nucleus collisions are studied in the framework of an extended Glauber model in which terms higher than the first (optical limit) in the phase shift expansion are considered. These are the so-called eclipse correction terms. The inelastic cross sections and distributions with respect to both the number of interacting nucleons and protons are calculated for various nucleus-nucleus interactions. The results show satisfactory agreement with the available experimental data.     

Elastic pd-scattering at high energies

Elastic pd-scattering at large angles is considered in terms of a virtual pion exchange model. The theoretical results are compared with the experimental data at 1 GeV proton energy.     

Perturbative QCD at high energies

A partial review of QCD at high energies is given. Factorization and the use of the renormalization group equation are emphasized. Topics discussed are the parton model, cut vertices in covariant and axial gauges, μ-pair production, jets, form factors, x → 1 limit of structure fu nctions, wide angle elastic scattering and heavy quarkonium exclusive decays. A discussion of mass and infrared singularities and a discussion of Sudakov effects are also included.     

Inclusive spectra of secondaries produced on nuclear targets at superhigh energies and with violation of Feynman scaling

Effects of Feynman scaling violation in yields of hadron secondaries inpA and πA collisions that arise when initial energy is increased are considered. There result from the growth of hadron-nucleon cross sections and an expected increase of the average transverse momenta of secondaries. The model of quark-gluon strings is used to calculate the inclusive spectra of secondaries. Interactions with a fixed number of nucleons are calculated, taking account of the growth of the slope parameter in elastichN scattering. Violation of Feynman scaling at superhigh energies turns out to be stronger than the additive quark model predicts it to be.