International Journal of Modern Physics: Conference Series

A primary question in hadron physics is how the mass scale for hadrons consisting of light quarks, such as the proton, emerges from the QCD Lagrangian even in the limit of zero quark mass. If one requires the effective action which underlies the QCD Lagrangian to remain conformally invariant and extends the formalism of de Alfaro, Fubini and Furlan to light-front Hamiltonian theory, then a unique, color-confining potential with a mass parameter $\kappa$ emerges. The actual value of the parameter $\kappa$ is not set by the model – only ratios of hadron masses and other hadronic mass scales are predicted. The result is a nonperturbative, relativistic light-front quantum mechanical wave equation, the Light-Front Schrödinger Equation which incorporates color confinement and other essential spectroscopic and dynamical features of hadron physics, including a massless pion for zero quark mass and linear Regge trajectories with the identical slope in the radial quantum number $n$ and orbital angular momentum $L$. The same light-front equations for mesons with spin $J$ also can be derived from the holographic mapping to QCD (3+1) at fixed light-front time from the soft-wall model modification of AdS₅ space with a specific dilaton profile. Light-front holography thus provides a precise relation between the bound-state amplitudes in the fifth dimension of AdS space and the boost-invariant light-front wavefunctions describing the internal structure of hadrons in physical space-time. One can also extend the analysis to baryons using superconformal algebra – $2\times 2$ supersymmetric representations of the conformal group. The resulting fermionic LF bound-state equations predict striking similarities between the meson and baryon spectra. In fact, the holographic QCD light-front Hamiltonians for the states on the meson and baryon trajectories are identical if one shifts the internal angular momenta of the meson ($L_M$) and baryon ($L_B$) by one unit: $L_M=L_B+1$. We also show how the mass scale $\kappa$ underlying confinement and the masses of light-quark hadrons determines the scale ${\mathrm{\Lambda }}_{\overline{MS}}$ controlling the evolution of the perturbative QCD coupling. The relation between scales is obtained by matching the nonperturbative dynamics, as described by an effective conformal theory mapped to the light-front and its embedding in AdS space, to the perturbative QCD regime. The data for the effective coupling defined from the Bjorken sum rule ${\alpha }_{g_1}(Q^2)$ are remarkably consistent with the Gaussian form predicted by LF holographic QCD. The result is an effective coupling defined at all momenta. The predicted value ${\Lambda }_{\overline{MS}}^{(N_F=3)}=0.440m_{\rho }=0.341\pm 0.024GeV$ is in agreement with the world average $0.339\pm 0.010GeV$. We thus can connect ${\mathrm{\Lambda }}_{\overline{MS}}$ to hadron masses. The analysis applies to any renormalization scheme.

We review the theory of the high energy scattering in QCD and gravity based on effective actions local in rapidities of usual and reggeized particles. The Euler-Lagrange equations are constructed with a variational approach for these actions and by using the invariance under the gauge and general coordinate transformations.

The interactions of hadron spin with gravity and electromagnetic field and their implication for hadron spin structure are considered. The extension of equivalence principle naturally leads to the closeness of vector meson magnetic moment to that of electroweak boson. This similarity is confirmed in the lattice QCD. The effective gravity in AdS/QCD allows to connect the $t$-dependence of GPDs (and therefore electromagnetic and gravitational form factors) with $k_T$-dependemce of TMDs. The possible cosmological implications of equivalence principle extension are discussed.

I describe a version of the Gell-Mann–Low scheme which is applicable to the Standard Model. First, I give a procedure for extracting input parameters of the theory from the Green’s functions. After that, an iterative procedure of expressing the Green’s functions in terms of the above parameters is given.

In this paper we study the contribution of the incoming hadrons’ polarization to the differential cross section of the hadron scattering at the ultra low energy limit. It is shown that their polarization does not have significant effect on the differential cross section of such scattering. The polarization of the outgoing hadrons is also analyzed.

In the wake of exploring uncertainty in the full angular distribution of the $B\to K\pi +{\mu }^{+}{\mu }^{-}$ caused by the presence of the intermediate scalar $K_0^{\ast }$ meson, we perform the straightforward calculation of the $B(B_s)\to S$ (S is a scalar meson) transition form factors in the full kinematical region within the covariant quark model. We restrict ourselves by the scalar mesons below 1 GeV: $a_0(980),f_0(500),f_0(980),K_0^{\ast }(800)$. As an application of the obtained results we calculate the widths of the semileptonic and rare decays $B(B_s)\to S\ell \bar{\nu }$, $B(B_s)\to S\ell \bar{\ell }$ and $B(B_s)\to S\nu \bar{\nu }$. We compare our results with those obtained in other approaches.

Role of the dispersive method in analysis of the $\pi \pi$ amplitudes in all important partial waves: $S$, $P$, $D$ and $F$ is presented. Widely discussed is the role of new (GKPY) and old (Roy) dispersion relations with imposed crossing symmetry condition. Example of a successful application of the GKPY and Roy’s equations in test of $\pi \pi$ amplitudes fitted to both experimental data and dispersion relations is presented. Short and purely mathematical proof of the uniqueness and correctness of the dispersive method used to precise determination of $\pi \pi$ interaction parameters is presented.

We present some recent results from soliton model calculations for the spectrum of baryons with a single heavy quark. The model comprises chiral symmetry for light flavors and (approximate) heavy spin–flavor symmetry for the heavy quarks. We focus on flavor symmetry breaking for strangeness degrees of freedom.

The unitary and analytic model for nucleons works very well. The model for spin ${\frac{1}{2}}^{+}$ baryons can predict static parameters for $\mathrm{\Lambda }$, ${\mathrm{\Sigma }}^{+}$, ${\mathrm{\Sigma }}^0$, ${\mathrm{\Sigma }}^{-}$, $\mathrm{\Xi }$, ${\mathrm{\Xi }}^{-}$. We prepared the scheme how to construct the model also for $\mathrm{\Delta }$ nucleon resonance. It was used to describe transition form factor $G_{\mathrm{\text{M}}}^{\ast }$ and the experimentally measured ratio $R_{\mathrm{\text{SM}}}$ with the help of relations for magnetic dipole transition and charge quadrupole form factors.

The effect of isoscalar S-wave processes $\pi \pi \to \pi \pi ,K\overline{K},\eta \eta$ is considered in the analysis of data (from the ARGUS, CLEO, CUSB, Crystal Ball, Belle, BABAR collaborations) on the bottomonia decays — $\mathrm{{\rm Y}}(mS)\to \mathrm{{\rm Y}}(nS)\pi \pi$ ($m>n,m=2,3,4,5,n=1,2,3$). It is shown that the dipion mass spectra of these decays are explained by the unified mechanism related to the contribution of the multichannel $\pi \pi$ scattering in the final states of these reactions. Since in the analysis the multichannel $\pi \pi$-scattering amplitudes did not change in comparison with the ones in our combined analysis of data on the multichannel $\pi \pi$ scattering and on the charmonia decays — $J/\psi \to \varphi (\pi \pi ,K\overline{K})$ and $\psi (2S)\to J/\psi (\pi \pi )$ (from the Crystal Ball, DM2, Mark II, Mark III, and BES II) — the results confirm all our earlier conclusions on the scalar mesons.

This report presents the investigations on the recently discovered scalar boson by the ATLAS experiment at the CERN Large Hadron Collider. The latest results fully exploit the data collected during LHC Run 1 to measure the properties of the new boson and within the current sensitivity confirm the identification of this particle with the Higgs boson of the Standard Model.

The latest top quark studies in proton-proton collisions at a centre-of-mass energy of 7 and 8 TeV with the ATLAS detector are reported. We present recent results on the top pair production inclusive cross-sections, top pair production differential cross-section in the resolved and boosted regimes, single top-quark production cross-sections measured in the t-channel, s-channel and W-boson associated processes, as well as the determination of the CKM matrix element $\left|V_{tb}\right|$. The results are compared with theoretical expectations. Latest ATLAS results on top properties will be also shown in terms of direct and pole mass, spin correlations and charge asymmetry.

We present a selection of recent heavy-flavour measurements by the ATLAS experiment using data collected during 2011 and 2012. The results include first analysis of associated production of $J/\psi$ with $Z$ boson, measurement of asymmetry parameter and helicity amplitudes in ${\mathrm{\Lambda }}_b^0\to J/\psi {\mathrm{\Lambda }}^0$ decay and a study of $B_c^{+}\to J/\psi D_s^{(\ast )+}$ decays. Moreover, the first observation of an excited $B_c^{\pm }$ meson state and results of a search for the $X_b$ and other hidden-beauty states are also shown.

Recent results of searches for exotic phenomena (new phenomena other than Supersymmetry) with the ATLAS experiment at the Large Hadron Collider conducted with proton–proton collision data at $\sqrt{s}=8$TeV taken 2012 were presented.

Experimental $dp\to ppn$ data have been obtained by nine detector configuration at 400 MeV at Internal Target Station of Nuclotron with using Polyethylene and Carbon targets. After detector calibration experimental data were compared with GEANT4 simulation. Experimental data have been taken at detector configuration in which possible relativistic effects can appear. $d{}^{3}He\to p{}^{4}He$ reaction is planned to be investigated at the extracted beam of Nuclotron at energy range of 1.0–1.75GeV. Presented simulation of the reaction is aimed on possibility to perform experimental study at extracted deuteron beam of Nuclotron with partial using of BM@N setup.

The results of the differential cross section measurements of dp-elastic scattering at energies from 500 to 1000 MeV/nucleon at Nuclotron JINR are reported. The data were obtained for angels range of 75-120${}^{\circ }$ in the c.m.s. The results are compared with existing world data.

The experiment on dp non-mesonic breakup at Internal Target Station at Nuclotron is presented. Recent results on the study of the dp-breakup reaction with 300–500MeV unpolarized deuteron beam at Internal Target Station at Nuclotron are discussed. Selection procedure of useful events for the $dp\to ppn$ reaction with the registration of two protons is shown. Further scientific program with polarized and unpolarized deuterons is discussed.

The scientific mission of the Compressed Baryonic Matter(CBM) experiment is the study of the nuclear matter properties at the high baryon densities in heavy ion collisions at the Facility of Antiproton and Ion Research (FAIR) in Darmstadt.

We present the results on JINR participation in the CBM experiment. JINR teams are responsible on the design, the coordination of superconducting(SC) magnet manufacture, its testing and installation in CBM cave. Together with Silicon Tracker System it will provide the momentum resolution better 1$\%$ for different configuration of CBM setup. The characteristics and technical aspects of the magnet are discussed. JINR plays also a significant role in the manufacture of two straw tracker station for the muon detection system. JINR team takes part in the development of new method for simulation, processing and analysis experimental data for different basic detectors of CBM.

The first results of the geometry GEANT3 simulation of the three-arm magnetic spectrometer SCAN3 are presented in this article. The possibility of detection of exotic nuclei (such as eta-mesic nucleus) with help of the SCAN3 and the Nuclotron internal target is shown.

The NA48/2 and NA62 collaborations report on recent results, current status, and prospects of kaon physics at the CERN-SPS. The NA62 collaborations aims to measure the decay $K^{\pm }\to {\pi }^{\pm }\nu \bar{\nu }$ with an uncertainty of 10% or better. The NA62 detector and preliminary results from a pilot run in 2014 are presented. In addition, recent results of the NA48/2 collaboration are reported. A search for Dark Photons has been performed in ${\pi }^0$ decays via the kaon decays $K^{\pm }\to {\pi }^{\pm }{\pi }^0$ and $K^{\pm }{\pi }^0{\mu }^{\pm }\nu$. No dark photon signal was observed and new upper limits on the mixing parameter ${ϵ}^2$ and the dark photon mass were computed. We also report the first observation of the kaon decay $K^{\pm }\to {\pi }^{\pm }{\pi }^0{e}^{+}{e}^{-}$.

It is demonstrated that for a determination of the mass difference of the $K_L^0$ and $K_S^0$ mesons an explicit theoretical formula to be derived by an assumption of the CP-conservation has been used by CPLEAR Collaboration in a fitting of the time-dependent CPLEAR data on ASYMMETRY.

So, in such procedure the mass difference $m_2-m_1$ of the $K_2^0$ and $K_1^0$ mesons has been found and in no case $m_L-m_S$ one as in this case the CP-violation has to be considered.

We present a broad range of Standard Model measurements performed in proton-proton collisions at the LHC on a variety of topics $W/Z+$jets production and ratios, the electroweak multi-boson production, $W/Z$ heavy flavor decay production, jet production, photon physics, the Standard Model soft QCD and diffractive physics. The latest public results from ATLAS experiment are obtained at the center-of-mass energy of both 7 TeV and 8 TeV, which covers total cross sections, fiducial cross sections, differential cross sections wherever available and comparison with Leading-Order/Next-to-Leading-Order/Next-to-Next-to-Leading-Order theory predictions. These measurements provide important tests for perturbative QCD, electroweak multi-boson interactions, Electroweak Symmetry Breaking over a broad kinematic range and constraints for PDFs. Model-independent new physics searches are also performed by probing anomalous gauge bosons couplings using effective Lagrangian or effective field theory formalism.

We present the spectra of negative charged particle production in Au $+$ Au collisions from STAR for the first phase of the RHIC Beam Energy Scan Program measured over a wide range of collision energy $\sqrt{s_{NN}}=7.7-200GeV$, and transverse momentum of produced particle in different centralities at $\left|\eta \right|<0.5$. The spectra demonstrate strong dependence on collision energy which enhances with $p_T$. An indication of self-similarity of negative charged particle production in Au $+$ Au collisions is found. The constituent energy loss as a function of energy and centrality of collisions and transverse momentum of inclusive particle was estimated in the $z$-scaling approach. The energy dependence of the model parameters - the fractal and fragmentation dimensions and “specific heat”, was studied.

The values of charged pion polarizabilities obtained in the framework of chiral perturbation theory at the level of two-loop accuracy are compared with the experimental result recently reported by COMPASS Collaboration. It is found that calculated value for the dipole polarizabilities ${(\alpha -\beta )}_{{\pi }^{\pm }}=(5.7\pm 1.0)\times 10^{-4}{\mathrm{\text{fm}}}^3$ fits quite well the experimental result ${(\alpha -\beta )}_{{\pi }^{\pm }}=(4.0\pm 1.2_{\mathrm{\text{stat}}}\pm 1.4_{\mathrm{\text{syst}}})\times 10^{-4}{\mathrm{\text{fm}}}^3$.

We briefly review motivation and results of the approach to QCD vacuum as a medium describable in terms of statistical ensemble of almost everywhere constant Abelian (anti-)self-dual gluon fields. An overview of the hadronization formalism based on this ensemble is presented. New results for radial excitations of light, heavy-light mesons and heavy quarkonia are presented. A possible interrelation between the present approach and holographic QCD with harmonic confinement is outlined.

A brief overview of searches for BFKL-evolution manifestations at high energies is presented. Data comparison with the predictions of BFKL-evolution in the leading logarithmic (LL) and next-to-leading logarithmic (NLL) approximations are discussed.

The electron and muon anomalous magnetic moments (AMM) are measured in experiments and studied in the Standard Model (SM) with the highest precision accessible in particle physics. The comparison of the measured quantity with the SM prediction for the electron AMM provides the best determination of the fine structure constant. The muon AMM is more sensitive to the appearance of New Physics effects and, at present, there appears to be a three- to four-standard deviation between the SM and experiment. The lepton AMMs are pure relativistic quantum correction effects and therefore test the foundations of relativistic quantum field theory in general, and of quantum electrodynamics (QED) and SM in particular, with highest sensitivity. Special attention is paid to the studies of the hadronic contributions to the muon AMM which constitute the main source of theoretical uncertainties of the SM.

I discuss a number of novel tests of QCD, measurements which can illuminate fundamental features of hadron physics. These include the origin of the “ridge” in proton-proton collisions; the production of the Higgs at high $x_F$; the role of digluon-initiated processes for quarkonium production; flavor-dependent anti-shadowing; the effect of nuclear shadowing on QCD sum rules; direct production of hadrons at high transverse momentum; and leading-twist lensing corrections; and the breakdown of perturbative QCD factorization. I also review the “Principle of Maximum Conformalit” (PMC) which systematically sets the renormalization scale order-by-order in pQCD, independent of the choice of renormalization scheme, thus eliminating an unnecessary theoretical uncertainty.

To describe the data on hadron production at high energies in the midarapidity region and not large transverse momenta $p_T$, we modify the simple exponential form of the $p_T$-spectrum. The hadron $p_T$-spectrum is presented in two parts due to the contributions of quarks and gluons, each of them has different energy dependence. The suggested approach alows us to describe rather satisfactorily the inclusive spectra of hadrons produced in $pp$ collisions at energies from the AGS up to LHC.

Data on cumulative particle production in pA collisions with momentum $p_L=18-400GeV/c$ are analyzed in the $z$-scaling approach. Scaling function $\mathrm{\Psi }(z)$ is constructed for different types of target nuclei and inclusive particle angle. The function is expressed via respective inclusive cross section and average multiplicity density of charged particles. This regime corresponds to low $z$ (low transverse momentum $p_T$). Validity of the concept was verified for this data. A-dependence of the scaling function is studied for low-$z$ region. Self-similarity of hadron production in pA collisions is confirmed over a wide kinematic range.

The study of $e^{+}{e}^{-}$-pairs production in n-p interactions was carried out at HADES set-up due to irradiation of proton target by deuteron beam at $T_{kin}^d=2.5$ AGeV. The momentum and angular distributions of proton-spectator an effective masses of $e^{+}{e}^{-}$-pairs were satisfactory described by a sum of various reactions of quasi-free n-p and p-p interactions.

We analyze the tauonic semileptonic baryon decays ${\mathrm{\Lambda }}_b^0\to {\mathrm{\Lambda }}_c^{+}+{\tau }^{-}+{\bar{\nu }}_{\tau }$ with particular emphasis on the lepton helicity flip contributions which vanish for zero lepton masses. We calculate the total rate, differential decay distributions, the longitudinal and transverse polarization components of the ${\mathrm{\Lambda }}_c^{+}$ and the ${\tau }^{-}$, and the lepton-side forward-backward asymmetries. We use the covariant confined quark model to provide numerical results on these observables.

The covariant quark model with infrared confinement (CQM) is a well-suited theoretical framework to describe large variety of hadronic processes, including rare decays of heavy mesons. In this text we focus on the reactions $B\to K^{(\ast )}{\mu }^{+}{\mu }^{-}$, which have been recently measured by Refs. 1–4. The measurements include also information about the angular distributions and their significance is given by possible New Physics (NP) effects which are predicted in numerous beyond Standard Model (SM) scenarios. Even with clever choice of experimental observables, a model dependence cannot be fully removed from the theoretical predictions. In this text we present the computation of the $B\to K^{(\ast )}$ form factors within the CQM and give results for some of the most commonly used observables ($A_{FB}$, $F_L$).

We discuss the influence of external magnetic field on strong decays of $K^{\ast }(892)$, $\varphi (1020)$ and ${\rho }^0(770)$ mesons. Due to increasing energy of $n=0$ Landau level of charged decay products, particular decay channels may become suppressed and isospin rules for strong decays can be violated. In the case of ${\rho }^0$ meson, enhanced production of photons and dileptons (with modified invariant mass) may occur. Similar considerations are applied to decays of ${\mathrm{\Xi }}^{\ast }(1530)$ baryon. We also suggest that static electromagnetic field of sufficient strength can modify the internal structure (wavefunction) of ${\eta }_c,$ J/$\mathrm{\Psi }$ and $\mathrm{{\rm Y}}(ns)$ mesons, and specific decay channels (e.g. CP — violating $\eta \to {\pi }^{+}{\pi }^{-}$) can become enhanced.

We study the role of the non-perturbative input to the transverse momentum dependent (TMD) gluon density in hard processes at the LHC. We derive the TMD gluon distribution from the fit of the inclusive hadron spectra measured at low transverse momenta in $pp$ collisions at the LHC and demonstrate that the best description of these spectra for larger hadron transverse momenta can be achieved by matching the derived TMD gluon distribution with the exact solution of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) equation obtained at small transverse momenta outside the saturation region. A special attention is put to the phenomenological applications of presented TMD parton densities to some LHC processes, which are sensitive to the quark and gluon content of a proton.