We report the first measurement of the azimuthal anisotropy of J/psi at forward rapidity (1.2 < vertical bar eta vertical bar < 2.2) in Au + Au collisions at root s(NN) = 200 GeV at the BNL Relativistic Heavy Ion Collider. The data were collected by the PHENIX experiment in 2014 and 2016 with integrated luminosity of 14.5 nb(-1). The second Fourier coefficient (v(2)) of the azimuthal distribution of J/psi is determined as a function of the transverse momentum (p(T)) using the event-plane method. The measurements were performed for several selections of collision centrality: 0%-50%, 10%-60%, and 10%-40%. We find that in all cases the values of v(2) (p(T)), which quantify the elliptic flow of J/psi, are consistent with zero. Within uncertainties, the results are consistent with measurements at midrapidity, indicating no significant elliptic flow of the J/psi within the quark-gluon-plasma medium at collision energies of root s(NN) = 200 GeV.

The jet cross section and jet-substructure observables in p +p collisions at root s =200 GeV were measured by the PHENIX Collaboration at the Relativistic Heavy Ion Collider (RHIC). Jets are reconstructed from charged-particle tracks and electromagnetic-calorimeter clusters using the anti-k(t) algorithm with a jet radius of R =0.3 for jets with transverse momentum within 8.0 < p(T) <40.0 GeV/c and pseudorapidity |eta| <0.15. Measurements include the jet cross section, as well as distributions of SoftDrop-groomed momentum fraction (z(g)), charged-particle transverse momentum with respect to jet axis (j(T)), and radial distributions of charged particles within jets (r). Also measured was the distribution of xi =-ln(z), where z is the fraction of the jet momentum carried by the charged particle. The measurements are compared to theoretical next-to and next-to-next-to-leading-order calculations, the pythia and herwig event generators, and to other existing experimental results. Indicated from these measurements is a lower particle multiplicity in jets at RHIC energies when compared to models. Also noted are implications for future jet measurements with sPHENIX at RHIC as well as at the future Electron-Ion Collider.

In literature, there are many estimators of finite population mean, some of which are superior to the others. In practical situations, all the information on sample units may not be available due to non-response in sample surveys. Thus, our objective in this study is to get more precise estimators of the finite population mean of the study variable under two-phase sampling in case of missing data. Three new logarithmic ratio cum logarithmic product type imputation methods and corresponding point estimators have been introduced and observed to be better under two-phase sampling, which adds contribution to the field of imputation techniques. The bias and mean square errors of the proposed estimators are calculated in terms of population parameters. The performance of the proposed estimators is compared theoretically and empirically as well with existing traditional estimators.

For the present work, we have used the HYDJET++ model to explore the production of pure multi-strange hadrons in Pb+Pb collisions at √(s_NN)= 2.76 TeV and √(s_NN)= 5.02 TeV collision energies, respectively. We have simulated the p_T-spectra and elliptic flow (v_2) of ϕ-meson and Ω-baryons comparing our results with ALICE experimental data and several phenomenological models (HIJING/BB, VISHNU, EPOS, AMPT, and Krakow) across various centrality intervals. Additionally, we have calculated the nuclear modification factors (R_AA and R_CP), which provide a perception of jet quenching phenomena. Hence, our findings enable the study of the energy and system dependence of ϕ and Ω hadrons production over a wide range of ultra-relativistic collision energies. We also present the particle ratios (Ω/ϕ, Ω^+/Ω^-, Ω/π, and ϕ/π), offering insights on the strangeness enhancement and chemical properties of the medium at both LHC collision energies.

We present the first forward-rapidity measurements of elliptic anisotropy of open-heavy-flavor muons at the Relativistic Heavy Ion Collider. The measurements are based on data samples of Au + Au collisions at root s(NN) = 200 GeV collected by the PHENIX experiment in 2014 and 2016 with integrated luminosity of 14.5 nb(-1). The measurements are performed in the pseudorapidity range 1.2 < vertical bar eta vertical bar < 2 and cover transverse momenta 1 < p(T) < 4 GeV/c. The elliptic flow of charged hadrons as a function of transverse momentum is also measured in the same kinematic range. We observe significant elliptic flow for both charged hadrons and heavy-flavor muons. The results show clear mass ordering of elliptic flow of light- and heavy-flavor particles. The magnitude of the measured v(2) is comparable to that in the midrapidity region. This indicates that there is no strong longitudinal dependence in the quark-gluon-plasma evolution between midrapidity and the rapidity range of this measurement at root s(NN) = 200 GeV.

In this work, we present the particle ratios, transverse momentum spectra, and elliptic flow ( v_2 ) of π ^± ,k^± , p, and p̅ in Au–Au collisions at √(s_NN)= 62.4, 39.0, 27.0, 19.6 and 11.5 GeV using HYDJET++ model. The particle ratios match the experimental data that validates the Cleymans-Reidlich parameterization of freeze-out parameters at lower beam energies under the HYDJET++ framework. The lower collision energies produce a system of high baryon chemical potential ( μ _B ) and have a lower inelastic cross section. The interplay between these effects affects the overall shape of the p_T spectra. The HYDJET++ model calculations for p_T spectra agree well with the available experimental data. The invariant yield ratio of central and peripheral collisions is independent of beam energy. The elliptic flow is calculated based on the scaling between initial and final azimuthal spatial anisotropy (k). This interpretation of v_2 successfully describes the experimental data for all the collision energies studied in this work. The positive correlation of k with beam energy leads to a small v_2 at lower collision energies. The hadrons containing strange quarks tend to have smaller values of k than the non-strange hadrons.

In the hydrodynamical description of heavy-ion collisions, the elliptic flow v_2 and triangular flow v_3 are sensitive to the quadrupole deformation β _2 of the colliding nuclei. We produce v_2 and v_3 ratios qualitatively and quantitatively in most-central Xe–Xe collisions at 5.44 TeV. By employing HYDJET++ model, we study the sensitivity of anisotropic flow coefficients and mean transverse momentum to the quadrupole deformation and system-size in isotopic Xe–Xe collisions. Flow observables strongly depend on the strength of nucleon–nucleon scattering occurring in even-A and odd-A nuclei. Flow for odd-A nuclei is suppressed in comparison to flow in even-A collisions. There exists a linear inter-dependence between p_T integrated anisotropic flow and nuclear deformation. Mean transverse momentum signifies the fireball temperature in body–body and tip–tip collisions. There exists a negative linear correlation of ⟨p_T⟩ with collision system-size and a positive correlation with nuclear deformation. Flow measurements in high-energy, heavy-ion collisions using isotopic collision systems, offer a new precision tool to study nuclear structure physics. Observation of nuclear structure properties like nuclear deformation in a heavy-ion collision such as this would be very interesting.

The J/ψ and ψ(2S) charmonium states, composed of cc̅ quark pairs and known since the 1970s, are widely believed to serve as ideal probes to test quantum chromodynamics in high-energy hadronic interactions. However, there is not yet a complete understanding of the charmonium-production mechanism. Recent measurements of J/ψ production as a function of event charged-particle multiplicity at the collision energies of both the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC) show enhanced J/ψ production yields with increasing multiplicity. One potential explanation for this type of dependence is multiparton interactions (MPI). We carry out the first measurements of self-normalized J/ψ yields and the ψ(2S) to J/ψ ratio at both forward and backward rapidities as a function of self-normalized charged-particle multiplicity in p+p collisions at √(s)=200 GeV. In addition, detailed pythia studies tuned to RHIC energies were performed to investigate the MPI impacts. We find that the PHENIX data at RHIC are consistent with recent LHC measurements and can only be described by pythia calculations that include MPI effects. The forward and backward ψ(2S) to J/ψ ratio, which serves as a unique and powerful approach to study final-state effects on charmonium production, is found to be less dependent on the charged-particle multiplicity.

High-momentum two-particle correlations are a useful tool for studying jet-quenching effects in the quark-gluon plasma. Angular correlations between neutral-pion triggers and charged hadrons with transverse momenta in the range 4–12 GeV/c and 0.5–7 GeV/c, respectively, have been measured by the PHENIX experiment in 2014 for Au+Au collisions at √(s__NN)=200 GeV. Suppression is observed in the yield of high-momentum jet fragments opposite the trigger particle, which indicates jet suppression stemming from in-medium partonic energy loss, while enhancement is observed for low-momentum particles. The ratio and differences between the yield in Au+Au collisions and p+p collisions, I_AA and Δ_AA, as a function of the trigger-hadron azimuthal separation, Δϕ, are measured for the first time at the Relativistic Heavy Ion Collider. These results better quantify how the yield of low-p_T associated hadrons is enhanced at wide angle, which is crucial for studying energy loss as well as medium-response effects.

Fractal concepts are employed to investigate the surface properties of tin sulfide (SnS) thin films, which are deposited on Fluorine-doped tin oxide (FTO)- coated glass substrates by the thermal evaporation (TE) technique. The surface topography of each deposited film is captured by AFM. The fractal dimensions of the AFM image were extracted through the Higuchi algorithm, and it is found that the thinner sample surface exhibits the maximum fractal dimension. The autocorrelation function and height-height correlation function are used to investigate the self-affinity behavior of surfaces. Dynamic surface roughening is characterized by different scaling exponents, such as the roughness exponent, the growth exponent, the dynamic scaling exponent, and the steepening exponent. It was observed that the values of average roughness, interface width, lateral correlation length, and mean square local slope are strongly influenced by film thickness. The self-affine fractal nature of thin film is estimated by the roughness exponent; however, island- or mound-type growth with quick surface roughening behavior is predicted by the growth exponent and the dynamic scaling exponent. Further, we have tried to correlate the optical properties such as transmission, reflection, and refractive index with the fractal dimension of SnS thin film. The increase in optical reflection with decreasing roughness indicates that absorber surfaces of the best crystalline films have the lowest reflectivity. The present results suggest that such surfaces, having a maximum fractal dimension and minimum optical reflectance, can be used as photon absorber layers for advanced solar cell devices.

The present investigation describes the optical properties of tin sulfide (SnS) thin films that were deposited on fluorine-doped tin oxide (FTO)-coated glass substrates at room temperature using the thermal evaporation method. The obtained films showed oriented growth with "p"-type conductivity. The effect of film thickness on the optical behavior of FTO/SnS was analyzed and compared with data from SnS films grown on glass and indium tin oxide substrates. Our study indicates that the properties of SnS film are independent of the substrate material. The optical band gap was found to decrease from 2.07 to 1.30 eV with increasing film thickness. We have seen a quantum confinement effect in samples whose grain size was less than 27 nm. The refractive indices of the samples were used to determine the single oscillator and dispersion energies using the Wemple-DiDomenico single-oscillator model. Other optical parameters were also determined using the transmission and absorption spectra. Besides grain size and number of defects, our data showed that the polarizability of the molecules along the Van der Waals direction influenced SnS optical properties. The interpretation was made possible considering the carrier concentration of free charges remained constant with varying film thickness. Such work provides insight into how to choose the appropriate thickness and, hence, grain sizes for optoelectronic applications.

By employing Monte Carlo HYDJET++ model (HYDrodynamics plus JETs), we produce anisotropic harmonic flow coefficients v_n (n = 4–7) in deformed Xe–Xe collisions at √(s_NN) = 5.44 TeV. We measure these harmonics with respect to a plane constructed using lower-order Fourier harmonics v_2 and v_3 (produced using reaction plane method). The cross-talk of elliptic and triangular flows in the model generates both even and odd harmonics of higher order. By combining analyses of higher harmonics with analyses of v_2 and v_3 , one can eliminate the uncertainty in modeling anisotropic flow from initial conditions and define quantities that only involve nonlinear hydrodynamic response coefficients. In this process, we study the individual response of higher-order flow coefficients to the lower-order flow coefficients through a power-law (relation v_n/ v_m^n/m ) scaling technique as a function of collision centrality. We report that these higher-order flow coefficients v_n (n = 4–7) are centrality dependent and strongly correlated with elliptic and triangular flow. The results are compared with data from recent ALICE, ATLAS and CMS experiments at LHC.

The PHENIX experiment measured the centrality dependence of two-pion Bose-Einstein correlation functions in root sNN = 200 GeV Au + Au collisions at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. The data are well represented by Levy-stable source distributions. The extracted source parameters are the correlation-strength parameter lambda, the Levy index of stability a, and the Levy-scale parameter R as a function of transverse mass m(T) and centrality. The lambda(m(T)) parameter is constant at larger values of m(T), but decreases as m(T) decreases. The Levy-scale parameter R(m(T)) decreases with mT and exhibits proportionality to the length scale of the nuclear overlap region. The Levy exponent alpha(m(T)) is independent of m(T) within uncertainties in each investigated centrality bin, but shows a clear centrality dependence. At all centralities, the Levy exponent a is significantly different from that of Gaussian ( alpha= 2) or Cauchy ( alpha = 1) source distributions. Comparisons to the predictions of Monte-Carlo simulations of resonance-decay chains show that, in all but the most peripheral centrality class (50%-60%), the obtained results are inconsistent with the measurements, unless a significant reduction of the in-medium mass of the eta meson is included. In each centrality class, the best value of the in-medium eta mass is compared to the mass of the. meson, as well as to several theoretical predictions that consider restoration of U-A(1) symmetry in hot hadronic matter.

The availability of high-multiplicity events at LHC energies provides a unique opportunity to examine the nature of phase-transition (PT) in heavy-ion collisions. Within the framework of HYDJET++ model, a systematic study of particle density fluctuations in narrow phase-space bins in Pb-Pb collisions at root s(NN) = 2.76 and 5.02 TeV energies is performed using the method of scaled factorial moments (SFM). The findings reveal the presence of intermittency in the 2-dimensional (2D) phase space distribution of charged particles at the LHC energies. The anomalous fractal dimensions, d(q), are observed to increase with the order of the moments q , suggesting the multifractal nature of the charged particle production. The parameter lambda(q) is found to exhibit a monotonically decreasing trend with the order of the moments but with no clear minima in lambda(q) values. Furthermore, the value of the critical exponent is estimated and compared with those predicted by other models reported at RHIC and LHC energies. The value of the critical exponent, nu, obtained in the present study, shows significant departure from the value similar to 1.304, as expected for the Ginzberg-Landau (GL) type second-order PT but exhibits a good level of agreement with the results obtained by other models at LHC energies. Copyright (c) 2024 EPLA

High-momentum two-particle correlations are a useful tool for studying jet-quenching effects in the quarkgluon plasma. Angular correlations between neutral-pion triggers and charged hadrons with transverse momenta in the range 4-12 GeV/c and 0.5-7 GeV/c, respectively, have been measured by the PHENIX experiment in 2014 for Au + Au collisions at root sNN = 200 GeV. Suppression is observed in the yield of high-momentum jet fragments opposite the trigger particle, which indicates jet suppression stemming from in-medium partonic energy loss, while enhancement is observed for low-momentum particles. The ratio and differences between the yield in Au + Au collisions and p + p collisions, I-AA and Delta(AA), as a function of the trigger-hadron azimuthal separation, Delta phi, are measured for the first time at the BNL Relativistic Heavy Ion Collider. These results better quantify how the yield of low-pT associated hadrons is enhanced at wide angle, which is crucial for studying energy loss as well as medium-response effects.

In the hydrodynamical description of heavy-ion collisions, the elliptic flow $\mathrm{v_{2}}$ and triangular flow $\mathrm{v_{3}}$ are sensitive to the quadrupole deformation $\mathrm{\beta_{2}}$ of the colliding nuclei. We produce $\mathrm{v_{2}}$ and $\mathrm{v_{3}}$ ratios qualitatively and quantitatively in most-central Xe-Xe collisions at 5.44 TeV. By employing HYDJET++ model, we study the sensitivity of anisotropic flow coefficients and mean transverse momentum to the quadrupole deformation and system-size in isotopic Xe-Xe collisions. Flow observables strongly depend on the strength of nucleon-nucleon scattering occuring in even-A and odd-A nuclei. Flow for odd-A nuclei is suppressed in comparison to flow in even-A collisions. There exists a linear inter-dependence between $\mathrm{p_{T}}$ integrated anisotropic flow and nuclear deformation. Mean transverse momentum signifies the fireball temperature in body-body and tip-tip collisions. There exists a negative linear correlation of $\mathrm{\langle p_{T} \rangle}$ with collision system-size and a positive correlation with nuclear deformation. Flow measurements in high-energy, heavy-ion collisions using isotopic collision systems, offer a new precision tool to study nuclear structure physics. Observation of nuclear structure properties like nuclear deformation in a heavy-ion collision such as this would be very interesting.

In this article, we have reported the transverse momentum (p(T) ) spectra and nuclear modification factors of (multi-) strange hadrons produced in Au+Au collisions at root sNN= 200 GeV using the Monte Carlo HYDJET++ model. For the present study, we have tuned few of the input parameters, in both soft as well as hard parts, of the model to appropriately describe the production of (multi-) strange hadrons. We have presented the p(T) -spectra of (multi-) strange hadrons in different centrality intervals. On comparing p(T) -spectra with the experimental data, we observe that the model does not achieve thermal equilibrium for kaons toward peripheral collisions and for omega baryons for all the centrality intervals. The R-AA results obtained by the model reproduce the experimental data well while the R-CP results show less suppression at higher p(T) than the experimental data. Further, HYDJET++ results are also compared with different theoretical models and discussed, wherever possible.

The invariant yield of electrons from open-heavy-flavor decays for $1

This work intends to address the issue of missing data by estimating the study variable's finite population mean with the help of two auxiliary variables using a modified exponential dual-to-ratio type imputation method and corresponding point estimator under simple random sampling. In terms of parameters, the ideal Bias and Mean Square Error (MSE) are determined. The effectiveness of the suggested estimator over various existing estimators has been shown through theoretical and empirical work.

The PHENIX experiment has performed a systematic study of identified charged-hadron ( p +/-, K +/-, p, p) production at midrapidity in p + Al, He-3+Au, and Cu + Au collisions at root s(NN) = 200 GeV and U + U collisions at root s(NN) = 193 GeV. Identified charged-hadron invariant transverse-momentum (p(T)) and transverse-mass (m(T)) spectra are presented and interpreted in terms of radially expanding thermalized systems. The particle ratios of K/ p and p/ p have been measured in different centrality ranges of large (Cu + Au and U + U) and small ( p + Al and He-3+Au) collision systems. The values of K/pi ratios measured in all considered collision systems were found to be consistent with those measured in p + p collisions. However, the values of p/pi ratios measured in large collision systems reach the values of approximate to 0.6, which is a factor of approximate to 2 larger than in p + p collisions. These results can be qualitatively understood in terms of the baryon enhancement expected from hadronization by recombination. Identified charged-hadron nuclear-modification factors (R-AB) are also presented. Enhancement of proton R-AB values over meson RAB values was observed in central He-3+Au, Cu + Au, and U + U collisions. The proton R-AB values measured in the p + Al collision system were found to be consistent with R-AB phi values of phi, pi(+/-), K-+/-, and pi(0) mesons, which may indicate that the size of the system produced in p + Al collisions is too small for recombination to cause a noticeable increase in proton production.