The cross section of reaction e^+e^-\toπ^+π^-π^+π^- is calculated for energies 0.65\leq \sqrt{s}\leq1 GeV in the framework of the generalized hidden local symmetry model. The calculations are compared with the data of CMD-2 and BaBaR. It is shown that the inclusion of heavy isovector resonances ρ(1450) and ρ(1700) is necessary for reconciling calculations with the data. It is found that at \sqrt{s}\approx1 GeV the contributions of above resonances are much larger, by the factor of 30, than the ρ(770) one, and are amount to a considerable fraction \sim0.3-0.6 of the latter at \sqrt{s}\sim m_ρ.
We explore the effects of shadowing on inclusive J/psi and Upsilon(1S) production at AFTER@LHC. We also present the rates as a function of p_T and rapidity for p+Pb and Pb+p collisions in the proposed AFTER@LHC rapidity acceptance.
Based on the generalized hidden local symmetry as the chiral model of pseudoscalar, vector, and axial vector mesons, the excitation curve of the reaction e^+e^-\toπ^+π^-π^+π^- is calculated for energies in the interval 0.65\leq \sqrt{s}\leq1 GeV. The theoretical predictions are compared to available data of CMD-2 and BaBaR. It is shown that the inclusion of heavy isovector resonances ρ(1450) and ρ(1700) is necessary for reconciling calculations with the data. It is found that at \sqrt{s}\approx1 GeV the contributions of the above resonances are much larger, by the factor of 30, than the ρ(770)…
A parameterization of the $\bar pp$ differential elastic scattering cross section in the beam momentum range from 2 to 16 GeV/c is proposed. The parameterization well describes the existing data including the observed diffraction pattern at four-momentum transfer $|t|$ up to 1.5-2.0 GeV$^2$. It can be used for detailed calculations of the radiation load on the detectors being designed for the PANDA detector at the future FAIR facility in Darmstadt.
We present the direct photon production for $1<p_{T}<10$ GeV/$c$ derived from continuum in the dielectron invariant mass region $0.1<M_{ee}<0.3$ GeV/$c^{2}$ from one billion $\sqrt{s_{NN}}=200$ GeV Au+Au events taken in year 2010 and 2011. A clear excess in the invariant yield compared to the number of binary collision scaled $p+p$ reference is observed in the \pt~range 1-4 GeV/$c$. Model calculations with contributions from thermal radiation and initial hard parton scattering are consistent within uncertainties with the direct photon invariant yield.
We obtain a detailed description of all available hadron multiplicity yields in central Pb--Pb collisions at LHC measured in the rapidity interval $|y|<0.5$. We find that the hadronization of the fireball at LHC occurs at nearly identical intensive physical bulk conditions for all centralities similar to those seen already at RHIC.
We report the direct virtual photon invariant yields in the transverse momentum ranges $1\!<\!p_{T}\!<\!3$ GeV/$c$ and $5\!<\!p_T\!<\!10$ GeV/$c$ at mid-rapidity derived from the dielectron invariant mass continuum region $0.10<M_{ee}<0.28$ GeV/$c^{2}$ for 0-80\% minimum-bias Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV. A clear excess in the invariant yield compared to the number-of-binary-collisions ($N_{bin}$) scaled $p+p$ reference is observed in the $p_T$ range $1\!<\!p_{T}\!<\!3$ GeV/$c$. For $p_T\!>6$ GeV/$c$ the production follows $N_{bin}$ scaling. Model calculations with contributions…
Recently, F. Wang commented on our work "Scaling properties of background- and chiral-magnetically-driven charge separation in heavy ion collisions at $\sqrt{s}_{\rm NN} = 200$ GeV" and made several claims to support his conclusion that our results are fallacious. His conclusion and claims are not only incorrect; they show a fundamental disconnect with the rudiments of the $R_{Ψ_2}(ΔS)$ correlator. This rebuttal addresses the root misconception responsible for Wang's false claims.
Discussions about Bose-Einstein correlations between decay products of coproduced W-bosons again raise the question about the behaviour of correlations if several strings are produced. This is studied by the multiplicity dependence of correlation functions of particle pairs with like-sign and opposite-sign charge in \bar{p}p reactions at sqrt{s} = 630 GeV.
We predict the elliptic flow parameter v_2 in U+U collisions at sqrt{s_{NN}}=200 GeV and in Pb+Pb collisions at sqrt{s_{NN}} = 2.76 TeV using a hybrid model in which the evolution of the quark gluon plasma is described by ideal hydrodynamics with a state-of-the-art lattice QCD equation of state, and the subsequent hadronic stage by a hadron cascade model.
Light nuclei and hyper-nuclei are produced in abundance in heavy-ion collisions. The production mechanism of these species in heavy-ion collisions still remains to be understood. In these proceedings, we report the transverse momentum and centrality dependence of elliptic flow ($v_2$) of $d$, $t$, and $^3\text{He}$ in Au+Au collisions at $\sqrt{s_{NN}}$ = 14.6, 19.6, 27, and 54.4 GeV. Mass number scaling of $v_2(p_T)$ of light nuclei is shown. We also report the first observation of hyper-nuclei $^{3}_Λ$H and $^{4}_Λ$H directed flow ($v_1$) in $\sqrt{s_{NN}}$ = 3 GeV mid-central (5-40\%) Au+Au…
In hydrodynamical modeling of ultrarelativistic heavy-ion collisions, the freeze-out is typically assumed to take place at a surface of constant temperature or energy density. A more physical approach is to assume that freeze-out takes place at a surface of constant Knudsen number. We evaluate the Knudsen number as a ratio of the expansion rate of the system to the pion scattering rate, and apply the constant Knudsen number freeze-out criterion to ideal hydrodynamical description of heavy-ion collisions at RHIC ($\sqrt{s_\mathrm{NN}}=200$ GeV) and the LHC ($\sqrt{s_\mathrm{NN}}=2760$ GeV) ener…
Direct photon emission in heavy-ion collisions is calculated within a relativistic micro+macro hybrid model and compared to the microscopic transport model UrQMD. In the hybrid approach, the high-density part of the collision is calculated by an ideal 3+1-dimensional hydrodynamic calculation, while the early (pre-equilibrium-) and late (rescattering-) phase are calculated with the transport model. We study both models with Au+Au-collisions at \sqrt{s_NN} = 200 GeV and compare the results to experimental data published by the PHENIX collaboration.
Direct photon production, in $\sqrt{s_{NN}}$=200 GeV Au+Au and in $\sqrt{s_{NN}}$=2.76 TeV Pb+Pb collisions, are studied in a hydrodynamic model. Ideal hydrodynamic model, initialised to reproduce experimentally charged particle spectra in RHIC and LHC energy, also reproduces the PHENIX and ALICE measurements for the direct photon spectra in Au+Au collisions at RHIC and Pb+Pb collisions at LHC. The model however produces less elliptic flow than in experiment. Discrepancy between experiment and hydrodynamic simulation is comparatively less in Pb+Pb collisions at LHC than in Au+Au collisions at …
We evaluate the measurement accuracy of the branching ratio of $h \to τ^+ τ^-$ at $\sqrt{s} = 250$ GeV and 500 GeV at the ILC with the ILD detector simulation. For the $\sqrt{s} = 250$ GeV, we assume the Higgs mass of $M_h = 120$ GeV, branching ratio of $\mathrm{Br}(h \to τ^+ τ^-) = 8.0 \ %$, beam polarization of $P(e^-, e^+) = (-0.8, +0.3)$, and integrated luminosity of $\int L \ dt = 250 \ \mathrm{fb ^{-1}}$. The Higgs-strahlung process $e^+ e^- \to Zh$ with $Z \to e^+ e^-$, $Z \to μ^+ μ^-$, $Z \to q\bar{q}$ mode are analyzed. The measurement accuracy is calculated to be $Δ(σ\cdot \mathrm{Br…
We obtain strangeness production as function of centrality in a statistical hadronization model analysis of all experimental hadron production data in Au--Au collisions at $\sqrt{s_{NN}}=62.4\GeV$. Our analysis describes successfully the yield of strange and multi-strange hadrons recently published. We explore condition of hadronization as a function of centrality and find universality for the case of chemical non-equilibrium in the hadron phase space corresponding to quark--gluon plasma (QGP) in chemical equilibrium.
We introduce the Statistical Hadronization with Resonances (SHARE) suite of programs and perform a study of particle multiplicities as well as bulk thermodynamic quantities for the RHIC Au--Au reactions at $\sqrt{s_{NN}}=130$ GeV. We also show that the statistical hadronization model, with parameters fitted to match pion, proton and hyperon ratios, in turn correctly and consistently reproduces rapidity particle multiplicity.
The transverse momentum spectra of secondary $η$ particles produced in $P+P$, $D+Au$ and $Au+Au$ interactions at $\sqrt{s_{NN}}=200$ GeV at different centralities have been studied in the light of a non-extensive thermodynamical approach. The results and the possible thermodynamical insights, thus obtained, about the hadronizing process have also been discussed in detail.
We will examine the Left-Right Twin Higgs(LRTH) Models as a solution of muon g-2 anomaly with the background of the Higgs global fit data. In the calculation, the joint constrains from the theory, the precision electroweak data, the 125 GeV Higgs data, the leptonic flavor changing decay μ\to eγdecays, and the constraints m_{ν_R}>m_T>m_{W_H} are all considered. And with the small mass of the ϕ^0, the direct searches from the $h\to ϕ^0ϕ^0$ channels can impose stringent upper limits on Br(h\to ϕ^0ϕ^0) and can reduce the allowed region of m_{ϕ^0} and f. It is concluded that the muon g-2 anomaly ca…
Single particle spectra as well as elliptic flow in Cu+Cu collisions at $\sqrt{s_{NN}}=200$ GeV are investigated within a hadronic cascade model and an ideal hydrodynamic model. Pseudorapidity distribution and transverse momentum spectra for charged hadrons are surprisingly comparable between these two models. However, a large deviation is predicted for the elliptic flow. The forthcoming experimental data will clarify the transport and thermalization aspects of matter produced in Cu+Cu collisions.
The ring structures that appear in Au+Au collisions at collision energies $\sqrt{s_{NN}}=$ 3 -- 30 GeV are studied. The calculations are performed within the model of three-fluid dynamics. It is demonstrated that a pare of vortex rings are formed, one at forward and another at backward rapidities, in ultra-central Au+Au collisions at $\sqrt{s_{NN}}>$ 4 GeV. The vortex rings carry information about early stage of the collision, in particular about the stopping of baryons. It is shown that these rings can be detected by measuring the ring observable $R_Λ$ even in rapidity range $0<y<0.5$ (or $-0…
We study UA5 published data on $p\bar{p}$ interaction cross-sections and on charged particles pseudorapidity distribution in single-diffractive, non-single diffractive and inelastic events and investigate their consistency/inconsistency.
Bilepton masses in the 3-3-1 models and the recently announced E821 experiment result are discussed. We get bounds on the bilepton masses 243 GeV $\leq M_Y \leq $ 357 GeV in the minimal model and 70 GeV $\leq M_Y \leq $ 115 GeV in the model with right-handed neutrinos.
We study the dependence of the Higgs boson mass on the supersymmetry breaking scale in the minimal supersymmetric extension of the standard Weinberg-Salam model. In particular, we find that for supersymmetry breaking scale $10^8$ GeV $\leq M_s \leq 10^{16}$ GeV and for $m^{pole}_{top} = 175 \pm 5 $ GeV the Higgs boson mass is 120 GeV $ \leq m_h \leq 160 $ GeV
We analyse the centrality dependence of thermal parameters deduced from hadron m ultiplicities in Au + Au collisions at $\sqrt{s_{NN}} = 130 GeV$. While the chemical freeze-out temperature and chemical potentials are found to be roughly centrality-independent, the strangeness saturation factor $γ_S$ increases with participant number towards unity, supporting the assumption of equilibrium freeze-out conditions in central collisions.
The latest preliminary combined results of the Higgs boson searches from the LEP experiments ALEPH, DELPHI, L3 and OPAL are presented. A general scan of the MSSM parameters is performed and leads to stringent lower mass limits and for the first time excludes low tan(beta) values.
Heavy-ion collisions at varying collision energies provide access to different regions of the QCD phase diagram. In particular collisions at intermediate energies are promising candidates to experimentally identify the postulated first order phase transition and critical end point. While heavy-ion collisions at low and high collision energies are theoretically well described by transport approaches and hydrodynamics+transport hybrid approaches, respectively, intermediate energy collisions remain a challenge. In this work, a modular hybrid approach, the SMASH-vHLLE-hybrid coupling 3+1D viscous …
Likelihood ratio tests are performed for the hypothesis that charged-particle multiplicities measured in Au-Au and Cu-Cu collisions at $\sqrt{s_{NN}} = 62.4$ and 200 GeV are distributed according to the negative binomial form. Results suggest that the hypothesis should be rejected in the all classes of collision systems and centralities of PHENIX-RHIC measurements. However, the application of the least-squares test statistic with systematic errors included shows that for the collision system Au-Au at $\sqrt{s_{NN}} = 62.4$ GeV the hypothesis could not be rejected in general.
In this paper we study inclusive production of vector charmonium states $J/ψ$ or $ψ(2S)$ in two-photon $\epem$-annihilation at $\sqrt s=10.6 \rm GeV$ using color-singlet model. Analytic expressions for differential cross sections, numerical values of total cross sections and plots of different distributions are presented. These distributions differ significantly from the one-photon case so these modes can be easily separated.
Recently interesting data on $dN_{ch}/dη$ in Au-Au collisions ($η=-\ln \tan (θ/2)$) with the centrality cuts have been reported by PHOBOS Collaboration. Their data are usually divided by the number of participants (nucleons) in collisions. Instead of this way, using the total multiplicity $N_{ch} = \int (dN_{ch}/dη)dη$, we find that there is scaling phenomenon among $(N_{ch})^{-1}dN_{ch}/dη= dn/dη$ with different centrality cuts at $\sqrt{s_{NN}} = 130$ GeV. To explain this scaling behavior of $dn/dη$, we consider the stochastic approach called the Ornstein-Uhlenbeck process with two sources. …
The production of dibaryons, light nuclei and hypertriton in the most central Au+Au collisions at $\sqrt{s_{NN}}=$ 11.5 and 200 GeV are investigated by using a naive coalescence model. The production of light nuclei is studied and found that the production rate reduces by a factor of 330 (1200) for each extra nucleon added to nuclei at $\sqrt{s_{NN}}=$ 11.5 (200) GeV. The $p_{T}$ integrated yield of multistrange hadrons falls exponentially as strangeness quantum number increases. We further investigate strangeness population factor $S_{3}, S_{2}$ as a function of transverse momentum as well as…
Based on Hijing-1.37 simulations, event-wise mean-pt fluctuations in Au-Au collisions at sqrt-sNN = 200 GeV are studied with graphical and numerical methods. This study shows that jets/minijets could represent a substantial source of mean-pt fluctuations, and jet quenching could reduce these fluctuations significantly. Mean-pt fluctuation measurements are a promising probe of correlation structure produced in the early stages of central collisions at RHIC energies.
The fractal characteristics of multi-particle final state are first studied in the $e^+e^-$ collision of $\sqrt{s_{NN}}=250$GeV, with the MC simulation generator Jetset7.4 and Herwig5.9. The result is shown that this multi-particle final state is self-affine fractal, and exists a double-Hurst-exponent phenomenon. Their fractal indices and the effective fluctuation strength are also predicted.
In this paper we have analyzed the production of pair charmonium mesons in the reactions $e^+ e^- \to J/ Ψχ_{c0}, e^+ e^-\to Ψ(2S) χ_{c0}$ at energy $\sqrt s = 10.6$GeV in the framework of the light cone formalism. In comparison with NRQCD the numerical results for the cross sections are in better agreement with experiment.
A thermal model, based on the Tsallis distribution and blast-wave model, is proposed to compute hadron double-differential spectra $d^{2}N/dp_{T}dy$ in $pp$ (also high energy $p\overline{p}$) collisions. It successfully describes the available experimental data on pion and quarkonia ($ϕ$, $J/ψ$, $ψ(2S)$, $Υ$ family) production at energies from $\sqrt{s} = 5$ GeV to the LHC ones. Simple parametrizations for the $\sqrt{s}$ dependence of the model parameters are provided allowing predictions for the yields of these particles at new collision energies. The model can be used also for the pion Bose-…
