Spin correlations of \varLambda[`\varLambda]\varLambda{\bar{\varLambda}} pairs as a probe of quark–antiquark pair production

The polarizations of Λ and [`\varLambda]{\bar{\varLambda}} are thought to retain memories of the spins of their parent s quarks and [`(s)]{\bar{s}} antiquarks, and are readily measurable via the angular distributions of their daughter protons and antiprotons. Correlations between the spins of Λ and [`\varLambda]{\bar{\varLambda}} produced at low relative momenta may therefore be used to probe the spin states of s [`(s)]s {\bar{s}} pairs produced during hadronization. We consider the possibilities that they are produced in a ³P₀ state, as might result from fluctuations in the magnitude of á[`(s)] s ?\langle {\bar{s}} s \rangle, a <sup>1</sup>S<sub>0</sub> state, as might result from chiral fluctuations, or a <sup>3</sup>S<sub>1</sub> or other spin state, as might result from production by a quark–antiquark or gluon pair. We provide templates for the p [`(p)]p {\bar{p}} angular correlations that would be expected in each of these cases, and discuss how they might be used to distinguish s [`(s)]s {\bar{s}} production mechanisms in pp and heavy-ion collisions.     

Analysis of the X(1835) and related baryonium states with Bethe-Salpeter equation

In this article, we study the mass spectrum of the baryon-antibaryon bound states p [`(p)] \bar{{p}} , S \Sigma [`(S)] \bar{{\Sigma}} , X \Xi [`(X)] \bar{{\Xi}} , L \Lambda [`(L)] \bar{{\Lambda}} , p [`(N)] \bar{{N}}(1440) , S \Sigma [`(S)] \bar{{\Sigma}}(1660) , X \Xi [`(X)]<sup>￠</sup> \bar{{\Xi}}^{{\prime}}_{} and L \Lambda [`(L)] \bar{{\Lambda}}(1600) with the Bethe-Salpeter equation. The numerical results indicate that the p [`(p)] \bar{{p}} , S \Sigma [`(S)] \bar{{\Sigma}} , X \Xi [`(X)] \bar{{\Xi}} , p [`(N)] \bar{{N}}(1440) , S \Sigma [`(S)] \bar{{\Sigma}}(1660) , X \Xi [`(X)]^￠ \bar{{\Xi}}^{{\prime}}_{} bound states maybe exist, and the new resonances X(1835) and X(2370) can be tentatively identified as the p [`(p)] \bar{{p}} and p [`(N)] \bar{{N}}(1440) (or N(1400)[`(p)] \bar{{p}} bound states, respectively, with some gluon constituents, and the new resonance X(2120) may be a pseudoscalar glueball. On the other hand, the Regge trajectory favors identifying the X(1835) , X(2120) and X(2370) as the excited h^￠ \eta^{{\prime}}_{}(958) mesons with the radial quantum numbers n = 3 , 4 and 5, respectively.     

Chiral color quark symmetry and possible constraints on the <Emphasis Type="Italic">G</Emphasis>′-boson mass from tevatron and LHC data

A gauge model featuring a chiral color symmetry of quarks was considered, and possible manifestations of this symmetry in proton-antiproton and proton-proton collisions at the Tevatron and LHC energies were studied. The cross section s_{t[`(t)]</sub>\sigma _{t\bar t} for the production of t[`(t)]t\bar t quark pairs at the Tevatron and the forward-backward asymmetry A_FB<sup>p[`(p)]</sup>A_{FB}^{p\bar p} in this process were calculated and analyzed with allowance for the contributions of the G′-boson predicted by the chiral color symmetry of quarks, the G′-boson massm <sub>G′</sub> and the mixing angle θ <sub>G</sub> being treated as free parameters of the model. Limits on m <sub>G′</sub> versus θ <sub>G</sub> were studied on the basis of data from the Tevatron on s<sub>t[`(t)]}\sigma _{t\bar t} and A_FB^p[`(p)]A_{FB}^{p\bar p}, and the region compatible with these data within one standard deviation was found in the m _G′-θ _G plane. The region ofm _G′-mass values that is appropriate for observing the G′-boson at LHC is discussed.     

Analysis of the <Emphasis Type="Italic">Y</Emphasis>(4140) and related molecular states with QCD sum rules

In this article, we assume that there exist scalar D^*[`(D)]<sup>*</sup>{D}^{\ast}{\bar {D}}^{\ast}, D<sub>s</sub><sup>*</sup>[`(D)]_s^*{D}_{s}^{\ast}{\bar{D}}_{s}^{\ast}, B^*[`(B)]<sup>*</sup>{B}^{\ast}{\bar {B}}^{\ast} and B<sub>s</sub><sup>*</sup>[`(B)]_s^*{B}_{s}^{\ast}{\bar{B}}_{s}^{\ast} molecular states, and study their masses using the QCD sum rules. The numerical results indicate that the masses are about (250–500) MeV above the corresponding D ^*–[`(D)]<sup>*</sup>{\bar{D}}^{\ast}, D <sub>s</sub> <sup>*</sup>–[`(D)]_s^*{\bar {D}}_{s}^{\ast}, B ^*–[`(B)]<sup>*</sup>{\bar{B}}^{\ast} and B <sub>s</sub> <sup>*</sup>–[`(B)]_s^*{\bar {B}}_{s}^{\ast} thresholds, the Y(4140) is unlikely a scalar D_s^*[`(D)]<sub>s</sub><sup>*</sup>{D}_{s}^{\ast}{\bar{D}}_{s}^{\ast} molecular state. The scalar D<sup>*</sup>[`(D)]^*D^{\ast}{\bar{D}}^{\ast}, D_s^*[`(D)]<sub>s</sub><sup>*</sup>D_{s}^{\ast}{\bar{D}}_{s}^{\ast}, B<sup>*</sup>[`(B)]^*B^{\ast}{\bar{B}}^{\ast} and B_s^*[`(B)]<sub>s</sub><sup>*</sup>B_{s}^{\ast}{\bar{B}}_{s}^{\ast} molecular states maybe not exist, while the scalar D￠<sup>*</sup>[`(D)]^￠*{D'}^{\ast}{\bar{D}}^{\prime\ast}, D_s^￠*[`(D)]<sub>s</sub><sup>￠*</sup>{D}_{s}^{\prime\ast}{\bar{D}}_{s}^{\prime\ast}, B<sup>￠*</sup>[`(B)]^￠*{B}^{\prime\ast}{\bar{B}}^{\prime\ast} and B_s^￠*[`(B)]_s^￠*{B}_{s}^{\prime\ast}{\bar{B}}_{s}^{\prime\ast} molecular states maybe exist.     

Predictions of HBT parameters in Pb + Pb collisions at √<Emphasis Type="Italic">s</Emphasis><Subscript><Emphasis Type="Italic">NN</Emphasis></Subscript> = 2.76 TeV from a hadronic rescattering model

A kinematic model based on the superposition of p + p collisions, relativistic geometry and final-state hadronic rescattering is used to predict two-boson HBT parameters in √s _NN = 2.76 TeV Pb + Pb collisions. A short proper time for hadronization is assumed. Previous calculations using this model which were performed for √s _NN = 200 GeV Au + Au collisions were shown to describe reasonably well the trends of two-pion HBT in experiments carried out at that energy, giving the present predictions for Pb + Pb at higher energy some degree of credibility.     

A new approach to diffusion-limited reaction rate theory

A new approach to the diffusion-limited reaction rate theory is developed on the base of a similar approach to consideration of Brownian coagulation, recently proposed by the author. The traditional diffusion approach to calculation of the reaction rate is critically analyzed. In particular, it is shown that the traditional approach is applicable only to the special case of reactions with a large reaction radius, [`(r)]<sub>A</sub> << R<sub>AB</sub> << [`(r)]_B\bar r_A \ll R_{AB} \ll \bar r_B (where [`(r)]<sub>A</sub>\bar r_A, [`(r)]_B\bar r_B are the mean interparticle distances), and becomes inappropriate to calculation of the reaction rate in the case of a relatively small reaction radius, R_AB << [`(r)]<sub>A</sub>R_{AB} \ll \bar r_A, [`(r)]_B\bar r_B. In the latter, most general case particles collisions occurmainly in the kinetic regime (rather than in the diffusion one) characterized by a homogeneous (at random) spatial distribution of particles. Homogenization of particles distribution occurs owing to particles diffusion mixing on the length scale of the mean interparticle distance with the characteristic diffusion time being small in comparison with the characteristic reaction time. The calculated reaction rate for a small reaction radius in 3D formally (and casually) coincides with the expression derived in the traditional approach for reactions with a large reaction radius, however, notably deviates at large times from the traditional result in the plane (2D) geometry.     

The Combined Effect of Connectivity and Dependency Links on Percolation of Networks

Percolation theory is extensively studied in statistical physics and mathematics with applications in diverse fields. However, the research is focused on systems with only one type of links, connectivity links. We review a recently developed mathematical framework for analyzing percolation properties of realistic scenarios of networks having links of two types, connectivity and dependency links. This formalism was applied to study Erdős-Rényi (ER) networks that include also dependency links. For an ER network with average degree [`(k)]\bar{k} that is composed of dependency clusters of size s, the fraction of nodes that belong to the giant component, P <sub>∞</sub>, is given by P<sub>￥</sub>=p<sup>s-1</sup>[1-exp(-[`(k)]pP_￥) ]^sP_{\infty}=p^{s-1}[1-\exp{(-\bar{k}pP_{\infty})} ]^{s} where 1−p is the initial fraction of randomly removed nodes. Here, we apply the formalism to the study of random-regular (RR) networks and find a formula for the size of the giant component in the percolation process: P _∞=p ^s−1(1−r ^k ) ^s where r is the solution of r=p ^s (r ^k−1−1)(1−r ^k )+1, and k is the degree of the nodes. These general results coincide, for s=1, with the known equations for percolation in ER and RR networks respectively without dependency links. In contrast to s=1, where the percolation transition is second order, for s>1 it is of first order. Comparing the percolation behavior of ER and RR networks we find a remarkable difference regarding their resilience. We show, analytically and numerically, that in ER networks with low connectivity degree or large dependency clusters, removal of even a finite number (zero fraction) of the infinite network nodes will trigger a cascade of failures that fragments the whole network. Specifically, for any given s there exists a critical degree value, [`(k)]<sub>min</sub>\bar{k}_{\min}, such that an ER network with [`(k)] ￡ [`(k)]_min\bar{k}\leq \bar{k}_{\min} is unstable and collapse when removing even a single node. This result is in contrast to RR networks where such cascades and full fragmentation can be triggered only by removal of a finite fraction of nodes in the network.     

η(1475) and <Emphasis Type="Italic">f</Emphasis><Subscript>1</Subscript>(1420) resonances in the decay processes <Emphasis Type="Italic">J</Emphasis>/ψ → γ(ρρ, γρ<Superscript>0</Superscript>, γϕ) and in γγ* collisions

A scenario that removes the contradiction between the suppression of the η(1475) → γγ decay width and the strong coupling of η(1475) to the ρρ, ωω, and γρ⁰ channels and which leads to a nontrivial prediction for the manifestation of η(1475) in γγ*(Q ²) collisions is considered. Data on the dependence of the cross section for the reaction γγ*(Q ²) → K[`(K)]pK\bar K\pi on the photon virtuality in the energy range 1.35–1.55 GeV are explained here by the production of an η(1475) resonance in contrast to their standard interpretation in terms of the f <sub>1</sub>(1420) resonance. Experimental verification of the present explanation requires determining the spin-parity of resonance contributions, R, in the reactions γγ*(Q <sup>2</sup>) R → R → K[`(K)]pK\bar K\pi and J/ψ → γR → γ(γρ⁰, γϕ).     

The study of longitudinal properties of the charge balance function

The charge balance function is studied in Au + Au collisions at ?[`(s_NN )]\surd \overline {s_{NN} } GeV using the STAR detector at the Relativistic Heavy-Ion Collider. Within the acceptance of the STAR TPC, it is found that the balance function is independent of the position of pseudorapidity windows with equal-size. It is also demonstrated for the first time at RHIC that the balance function divided by a scaling factor related to pseudorapidity is independent of the width and position of the pseudorapidity window. Moreover, Such a scaled balance function is further found to exist in the subset of particles with the same restricted transverse-momentum range.     

D-mesons and charmonium states in hot isospin asymmetric strange hadronic matter

We study the properties of D and [`(D)] \bar{{D}} mesons in hot isospin asymmetric strange hadronic matter, arising due to their interactions with the hadrons in the hyperonic medium. The interactions of D and [`(D)] \bar{{D}} mesons with these light hadrons are derived by generalizing the chiral SU(3) model used for the study of hyperonic matter to SU(4). The nucleons, hyperons, the scalar isoscalar meson, σ and the scalar-isovector meson, d \delta as modified in the strange hadronic matter, modify the masses of D and [`(D)] \bar{{D}} mesons. It is found that, as compared to the [`(D)] \bar{{D}} mesons ([`(D<sup>0</sup>)] \bar{{D^0}}, D <sup>−</sup>), the properties of the D mesons (D <sup>0</sup>, D <sup>+</sup>) are more sensitive to the isospin asymmetry at high densities. On the other hand, the effects of strangeness fraction are found to be more dominant for the [`(D)] \bar{{D}} mesons as compared to the D mesons and these modifications are observed to be particularly appreciable at high densities. We also study the mass modifications of the charmonium states J/ψ, ψ(3686) and ψ(3770) in the isospin asymmetric strange hadronic matter at finite temperatures and investigate the possibility of the decay of the charmonium states into D [`(D)] \bar{{D}} pairs in the hot hadronic medium. The mass modifications of these charmonium states arise due to their interaction with the gluon condensates of QCD, simulated by a scalar dilaton field introduced to incorporate the broken scale invariance of QCD within the effective chiral model. The effects of finite quark masses are taken into account in the trace of the energy momentum tensor in QCD, while investigating the medium modification of the charmonium masses through the modification of the gluon condensate in the medium. We also compute the partial decay widths of the charmonium states to the D [`(D)] \bar{{D}} pairs in the hadronic medium. The strong dependence on density of the in-medium properties of the D, [`(D)] \bar{{D}} and the charmonium states, as well as the partial decay widths of charmonium states to D [`(D)] \bar{{D}} pairs, found in the present investigation, will be of direct relevance in observables like open charm enhancement as well as J/ψ suppression in the compressed baryonic matter (CBM) experiments at the future Facility for Antiproton and Ion Research, GSI, where the baryonic matter at high densities is planned to be produced.     

Analysis of the <Emphasis Type="Italic">Y</Emphasis>(4140) with QCD sum rules

In this article, we assume that there exists a scalar D_s^*[`(D)]<sub>s</sub><sup>*</sup>D_{s}^{\ast}{\bar{D}}_{s}^{\ast} molecular state in the J/ψ φ invariant mass distribution, and we study its mass using the QCD sum rules. The predictions depend heavily on the two criteria (pole dominance and convergence of the operator product expansion) of the QCD sum rules. The value of the mass is about M<sub>Ds<sup>*</sup>[`(D)]s^*</sub>=(4.43±0.16)M_{D_{s}^{\ast}{\bar{D}}_{s}^{\ast}}=(4.43\pm0.16)  GeV, which is inconsistent with the experimental data. The D_s^*[`(D)]_s^*D_{s}^{\ast}{\bar{D}}_{s}^{\ast} is probably a virtual state and is not related to the meson Y(4140). Another possibility, such as a hybrid charmonium, is not excluded.     

Study of $$qqqc\bar c$$ five quark system with three kinds of quark-quark hyperfine interaction

The low-lying energy spectra of five quark systems uudc[`(c)]uudc\bar c (I = 1/2, S = 0) and udsc[`(c)]udsc\bar c (I = 0, S = 1) are investigated with three kinds of schematic interaction: the chromomagnetic interaction, the flavor-spin-dependent interaction and the instanton-induced interaction. In all the three models, the lowest five-quark state (uudc[`(c)]uudc\bar c or udsc[`(c)]udsc\bar c) has an orbital angular momentum L = 0 and the spin-parity J ^P = 1/2⁻; the mass of the lowest udsc[`(c)]udsc\bar c state is heavier than the lowest uudc[`(c)]uudc\bar c state.     

Topology of hadronic flow for Higgs production at hadron colliders

Hadronic radiation provides a tool to distinguish different topologies of colour flow in hard scattering processes. We study the structure of hadronic flow corresponding to Higgs production and decay in high-energy hadron-hadron collisions. In particular, the signal gg ? H ? b [`(b)]gg \to H \to b \bar b and background gg ? b [`(b)]gg \to b \bar b processes are shown to have very different radiation patterns, and this may provide a useful additional method for distinguishing Higgs signal events from the QCD background.     

The Transformations from the New Intermediate Entangled State

The new intermediate entangled state |η;θ〉 is proposed by virtue of IWOP technique, which is the common eigenvector of [([^(x)]₁ - [^(x)]₂)cosq-([^(p)]₁ - [^(p)]₂)sinq][(\hat{x}_{1} - \hat{x}_{2})\cos\theta -(\hat{p}_{1} - \hat{p}_{2})\sin\theta ] and [([^(x)]₁ +[^(x)]₂)sinq+ ([^(p)]₁ + [^(p)]₂)cosq][(\hat{x}_{1} +\hat{x}_{2})\sin\theta + (\hat{p}_{1} + \hat{p}_{2})\cos\theta ]. The squeezing transformation operator, Hadamard transformation operator, Fresnel transformation operator and Radon transform operator are constructed by |η;θ〉.     

Canonical interpretation of the <Emphasis Type="Italic">η</Emphasis><Subscript>2</Subscript>(1870)

We argue that the mass, production, total decay width, and decay pattern of the η ₂(1870) do not appear to contradict with the picture of it as being the conventional 2 ¹ D ₂ q[`(q)]q\bar{q} state. The possibility of the η <sub>2</sub>(1870) being a mixture of the conventional q[`(q)]q\bar{q} and a hybrid is also discussed.     

Search for higher laying charmonium states and charmed hybrids in experiments using antiproton beam with momentum ranging from 1 GeV/<Emphasis Type="Italic">c</Emphasis> to 15 GeV/<Emphasis Type="Italic">c</Emphasis>

The elaborated analysis of spectrum of scalar and vector charmonium states in the mass region above D[`(D)]D\bar D — threshold is given. The combined approach based on the potential model and relativistic spherical symmetric top model for decay products has been proposed. Ten radial excited states of charmonium in the mass region above D[`(D)]D\bar D — threshold are anticipated to exist in the framework of the combined approach. The experimental data from different collaborations were analyzed. Especial attention was given to the new states with the hidden charm discovered recently. Eight of these states may be interpreted as higher laying radial excited charmonium states. But much more data on different decay modes are needed for deeper analysis. These data can be derived directly from the experiments using high quality antiproton beam with the momentum ranging from 1 GeV/c to 15 GeV/c (PANDA experiment at FAIR).     

Beam-energy and system-size dependence of dynamical net charge fluctuations

We present measurements of net charge fluctuations in Au + Au collisions at ?{s_NN }\sqrt {s_{NN} } = 19.6, 62.4, 130, and 200 GeV, Cu + Cu collisions at ?{s_NN }\sqrt {s_{NN} } = 62.4, 200 GeV, and p + p collisions at ?s\sqrt s = 200 GeV using the net charge dynamical fluctuations measure ν+ −,dyn. The dynamical fluctuations are non-zero at all energies and exhibit a rather modest dependence on beam energy. We find that at a given energy and collision system, net charge dynamical fluctuations violate 1/N _ch scaling, but display approximate 1/N _part scaling. We observe strong dependence of dynamical fluctuations on the azimuthal angular range and pseudorapidity widths.