The Behavior of the Slope of Elastic Nucleon Scattering at Small Transfer Momenta and Recent Ua4 Data

Theoretical predictions for the behavior of the slope of the nucleon-nucleon scattering and another parameters of the differential cross sections in the framework of the dynamic model are compared with the recent UA4 data at small transfer momenta and at the centre-of-mass energy of 541 GeV. The predictions at superhigh energies are considered.Comment: 6 pages, 1 fig.-fig.ps, LATEX., JINR E2-93-43

Supercritical Pomeron and eikonal representation of the diffraction scattering amplitude

The intercept of the supercritical Pomeron is examined with the use of different forms of the scattering amplitudes of the bare Pomeron. The one-to-one correspondence between the eikonal phase and the ratio of the elastic and total cross section is shown. Based on new experimental data of the CDF Collaboration, the intercept and power of the logarithmic growth of the bare and total Pomeron amplitude are analyzed. It is shown that as a result of the eikonalization procedure, the bare QCD Pomeron becomes compatible with experiment.Comment: LaTex text of the article + 1 Fig.1 in LaTex for

Lepton Phenomenology of Stueckelberg Portal to Dark Sector

We propose an extension of the Standard Model (SM) with a $U_{A'}(1)$ gauge invariant Dark Sector connected to the SM via a new portal arising in the framework of dark photon $A'$ mass generation via Stueckelberg mechanism. This mechanism implies the existence of a scalar field $\sigma$, which is shift-transformed under this group and resembles an axion-like particle (ALP) widely addressed in the literature in different contexts. The effective dim=5 operators constructed of the covariant derivative of the $\sigma$ field generate flavor non-diagonal renormalizable couplings of both $\sigma$ and $A'$ to the SM fermions $\psi$. Contrary to the conventional kinetic mixing portal, in our scenario flavor diagonal $A'$-$\psi$ couplings are not proportional to the fermion charges. These features drastically change the phenomenology of dark photon $A'$ relaxing or avoiding some previously established experimental constraints. We focus on the phenomenology of the described scenario of the Stueckelberg portal in the lepton sector and analyze the contribution of the dark sector fields $A'$ and $\sigma$ to the anomalous magnetic moment of muon $(g-2)_{\mu}$, Lepton Flavor Violating decays $l_{i}\to l_{k}\gamma$ and $\mu-e$ conversion in nuclei. We obtain limits on the model parameters from the existing experimental data on the corresponding observables.Comment: 15 pages, 8 figure

Second virial coefficients of light nuclear clusters and their chemical freeze-out in nuclear collisions

Here we develop a new strategy to analyze the chemical freeze-out of light (anti)nuclei produced in high energy collisions of heavy atomic nuclei within an advanced version of the hadron resonance gas model. It is based on two different, but complementary approaches to model the hard-core repulsion between the light nuclei and hadrons. The first approach is based on an approximate treatment of the equivalent hard-core radius of a roomy nuclear cluster and pions, while the second approach is rigorously derived here using a self-consistent treatment of classical excluded volumes of light (anti)nuclei and hadrons. By construction, in a hadronic medium dominated by pions, both approaches should give the same results. Employing this strategy to the analysis of hadronic and light (anti)nuclei multiplicities measured by ALICE at $\sqrt{s_{NN}} =2.76$ TeV and by STAR at $\sqrt{s_{NN}} =200$ GeV, we got rid of the existing ambiguity in the description of light (anti)nuclei data and determined the chemical freeze-out parameters of nuclei with high accuracy and confidence. At ALICE energy the nuclei are frozen prior to the hadrons at the temperature $T = 175.1^{+2.3}_{-3.9}$ MeV, while at STAR energy there is a single freeze-out of hadrons and nuclei at the temperature $T = 167.2 \pm 3.9$ MeV. We argue that the found chemical freeze-out volumes of nuclei can be considered as the volumes of quark-gluon bags that produce the nuclei at the moment of hadronization.Comment: 15 pages, 4 figures, 3 table

Extra-Curricular Activities as an Important Factor for Developing Subject Qualities of Future Engineers

We examine the need to develop the subjective qualities of students at technical universities based on the analysis of Russian and foreign research on future engineers’ training. We consider the peculiarities of future engineers’ educational process, based on the importance of extracurricular activities in the development of such qualities. The purpose of the study is to test the hypothesis about the effectiveness of developing the subjective qualities of future engineers by involving them in extracurricular activities that were formed at the initial stage. The paper describes a pedagogical experiment that includes three stages. The set of research methods includes analysis, synthesis, comparison, generalization, pedagogical observation, questionnaire survey, testing, conversation, expert assessments, and statistics. We present different directions and types of activities organized within the experimental work with pedagogical support. Besides, we give examples of extracurricular activities that contribute to the successful development and manifestation of the specified personal qualities in students. The paper contains evidence of the effectiveness of extracurricular student activities as a factor in developing subjective qualities

Long-term operation of a multi-channel cosmic muon system based on scintillation counters with MRS APD light readout

A Cosmic Ray Test Facility (CRTF) is the first large-scale implementation of a scintillation triggering system based on a new scintillation technique known as START. In START, the scintillation light is collected and transported by WLS optical fibers, while light detection is performed by pairs of avalanche photodiodes with the Metal-Resistor-Semiconductor structure operated in the Geiger mode (MRS APD). START delivers 100% efficiency of cosmic muon detection, while its intrinsic noise level is less than 10^{-2} Hz. CRTF, consisting of 160 START channels, has been continuously operated by the ALICE TOF collaboration for more than 25 000 hours, and has demonstrated a high level of stability. Fewer than 10% of MRS APDs had to be replaced during this period.Comment: Proceedings of NDIP-2008. 8 pages, 8 figures, 6 reference

Measurement of Exclusive pi(0) Electroproduction Structure Functions and their Relationship to Transverse Generalized Parton Distributions

Exclusive pi(0) electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in Q(2), x(B), t, and phi(pi), in the Q(2) range from 1.0 to 4.6 GeV2, -t up to 2 GeV2, and x(B) from 0.1 to 0.58. Structure functions sigma(T) + epsilon sigma(L), sigma(TT), and sigma(LT) were extracted as functions of t for each of 17 combinations of Q(2) and x(B). The data were compared directly with two handbag-based calculations including both longitudinal and transversity generalized parton distributions (GPDs). Inclusion of only longitudinal GPDs very strongly underestimates sigma(T) + epsilon sigma(L) and fails to account for sigma(TT) and sigma(LT), while inclusion of transversity GPDs brings the calculations into substantially better agreement with the data. There is very strong sensitivity to the relative contributions of nucleon helicity-flip and helicity nonflip processes. The results confirm that exclusive pi(0) electroproduction offers direct experimental access to the transversity GPDs