Study of KNO-G scaling in neutrino interactions

KNO scaling was put forward by Koba, Nielsen, and Olesen (KNO) in 1972. Although it is an important tool for explaining multiplicity distributions and formulated for the asymptotic energies, it has been applied at a finite energy range where its formulation is not self-consistent. A consistent generalization, known as KNO-G scaling, was done by Golokhvastov in 1977 to make it self-consistent. Then, KNO-G scaling has been successfully applied in many experiments and its validity has been reported. In this study, KNO-G scaling is tested in neutrino interactions. The charged hadron multiplicity of CHORUS, OPERA, NOMAD and DONUT, which are neutrino experiments, is compared and tested the KNO-G scaling. It is observed that neutrino data are consistent with KNO-G scaling. A fit is superimposed on the data sets and fit parameters are compared.

Numerical solutions to Giovannini’s parton branching equation up to TeV energies at the LHC

The full Giovannini parton branching equation is integrated numerically using the fourth-order Runge-Kutta method. Using a simple hadronization model, a charged-hadron multiplicity distribution is obtained. This model is then fitted to various experimental data up to the TeV scale to study how the Giovannini parameters vary with collision energy and type. The model is able to describe hadronic collisions up to the TeV scale and reveals the emergence of gluonic activity as the center-of-mass energy increases. A prediction is made for [Formula: see text].

Rapid Change of Multiplicity Fluctuations in System Size Dependence at SPS Energies

Recent preliminary results on multiplicity fluctuations in p+p, Be+Be and Ar+Sc collisions from the NA61/SHINE collaboration are presented. The scaled variance of charged hadron multiplicity changes little when going from p+p to Be+Be collisions and drops dramatically from Be+Be to Ar+Sc interactions. The centrality selection procedure and the influence of volume fluctuations are discussed. Comparisons with the EPOS event generator are shown.

Development of dark disk model of positron anomaly origin

Dark disk model could be a remedy for dark matter (DM) explanation of positron anomaly (PA) in cosmic rays (CR). The main difficulty in PA explanation relates to cosmic gamma-radiation which is inevitably produced in DM annihilation or decay leading to tension with respective observation data. Introduction of “active” (producing CR) DM component concentrating in galactic disk alleviates this tension. Earlier, we considered 2-lepton modes, with branching ratios being chosen to fit in the best way all the observation data. Here we considered, in the framework of the same dark disk model, two cases: 2-body final state annihilation and 4-body one, and in each case a quark mode is added to the leptonic ones. It is shown that 4-body mode case is a little better than 2-body one from viewpoint of quality of observation data description at the fixed all other parameters (of CR propagation, background, disk height). The values of DM particle mass around 350[Formula: see text]GeV and 500[Formula: see text]GeV are more favorable for 2- and 4-body modes, respectively. Higher values would improve description of data on positrons only but accounting for data on gamma-radiation prevents it because of unwanted more abundant high-energy gamma production. Inclusion of the quark modes improves a little fitting data in both 4- and 2-body mode cases, contrary to naive expectations. In fact, quark mode has a bigger gammas yield than that of most gamma-productive leptonic mode — tau, but they are softer due to bigger final state hadron multiplicity.

Separate freeze-out of strange particles and the quark-hadron phase transition

The scenario of the independent chemical freeze-outs for strange and nonstrange particles is discussed. Within such a scenario an apparent in-equilibrium of strangeness is naturally explained by a separation of chemical freeze-out of strange hadrons from the one of non-strange hadrons, which, nevertheless, are connected by the conservation laws of entropy, baryonic charge and third isospin projection. An interplay between the separate freeze-out of strangeness and its residual non-equilibrium is studied within an elaborate version of the hadron resonance gas model. The developed model enables us to perform a high-quality fit of the hadron multiplicity ratios measured at AGS, SPS and RHIC with an overall fit quality ϰ2/dof = 0:93. A special attention is paid to a description of the Strangeness Horn and to the well-known problem of selective suppression of Δ- and ж hyperons. It is remarkable that for all collision energies the strangeness suppression factor γs is about 1 within the error bars. The only exception is found in the vicinity of the center-of-mass collision energy 7.6 GeV, at which a residual enhancement of strangeness of about 20 % is observed.

Radial Flow in a Multiphase Transport Model at FAIR Energies

Azimuthal distributions of radial velocities of charged hadrons produced in nucleus-nucleus (AB) collisions are compared with the corresponding azimuthal distribution of charged hadron multiplicity in the framework of a multiphase transport (AMPT) model at two different collision energies. The mean radial velocity seems to be a good probe for studying radial expansion. While the anisotropic parts of the distributions indicate a kind of collective nature in the radial expansion of the intermediate “fireball,” their isotropic parts characterize a thermal motion. The present investigation is carried out keeping the upcoming Compressed Baryonic Matter (CBM) experiment to be held at the Facility for Antiproton and Ion Research (FAIR) in mind. As far as high-energy heavy-ion interactions are concerned, CBM will supplement the Relativistic Heavy-Ion Collider (RHIC) and Large Hadron Collider (LHC) experiments. In this context our simulation results at high baryochemical potential would be interesting, when scrutinized from the perspective of an almost baryon-free environment achieved at RHIC and LHC.

More Results from the Opera Experiment at the Gran Sasso Underground Lab

The OPERA experiment reached its main goal by proving the appearance of [Formula: see text] in the CNGS [Formula: see text] beam. Five [Formula: see text] candidates fulfilling the analysis defined in the proposal were detected with a S/B ratio of about ten allowing to reject the null hypothesis at 5.1[Formula: see text]. The search has been extended by loosening the selection criteria in order to obtain a statistically enhanced, lower purity, signal sample. One such interesting neutrino interaction with a double vertex topology having a high probability of being a [Formula: see text] interaction with charm production is reported. Based on the enlarged data sample the estimation of [Formula: see text][Formula: see text] in appearance mode is presented. The search for [Formula: see text] interactions has been extended over the full data set with a more than twofold increase in statistics with respect to published data. The analysis of the [Formula: see text] channel is updated and the implications of the electron neutrino sample in the framework of the 3+1 neutrino model is discussed. An analysis of [Formula: see text] interactions in the framework of the sterile neutrino model has also been performed. Finally, the results of the study of charged hadron multiplicity distributions is presented.