arXiv subjects

Wei-Ning Zhang

Publications and source records attributed to Wei-Ning Zhang.

At least 19 recordsLinked to original sources

arXiv2024

Multiboson Hanbury Brown-Twiss correlations for partially coherent sources in relativistic heavy-ion collisions in a multiphase transport model

We use a multi-phase transport (AMPT) model to study multi-pion and multi-kaon Hanbury Brown-Twiss (HBT) correlations for the partially coherent particle-emitting sources in relativistic heavy-ion collisions. A density-dependent longitudinal coherent emission length and density-dependent transverse coherent emission length are introduced in calculating the multi-boson HBT correlation functions of the partially coherent sources. We compare the model results of three- and four-pion HBT correlation functions with experimental data in Pb-Pb collisions at center-of-mass energy $\sqrt{s_{NN}}=$2.76 TeV, and investigate the influences of boson coherent emissions on the multi-pion and multi-kaon correlation functions, respectively. We find that all of the three- and four-pion correlation functions of the partially coherent sources are consistent with experimental data. Coherent emission leads to the intercept decreases of the multi-boson correlation functions. The intercepts of the multi-kaon correlation functions of the partially coherent source are higher than those of the multi-pion correlation functions, because low kaon densities lead to smaller kaon coherent emission lengths than pion emission lengths. The intercepts of multi-boson correlation functions of partially coherent sources in high transverse momentum intervals are higher than those in low transverse momentum intervals because particle de Broglie wavelengths are small at high momenta.

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arXiv2024

Two-pion interferometry for partially coherent sources in relativistic heavy-ion collisions in a multi-phase transport model

We perform two-pion Hanbury Brown-Twiss (HBT) interferometry for the partially coherent pion-emitting sources in relativistic heavy-ion collisions, using a multi-phase transport (AMPT) model. A longitudinal coherent emission length, as well as a transverse coherent emission length, are introduced to the pion generation coordinates in calculating the HBT correlation functions of the partially coherent sources. We compare the model results with and without coherent emission conditions with experimental data in Au-Au collisions at center-of-mass energy $\sqrt{s_{NN}}=$200 GeV, and in Pb-Pb collisions at center-of-mass energy $\sqrt{s_{NN}}=$2.76 TeV, and find that the HBT results of the partially coherent sources are closer to the experimental data than those of chaotic sources.

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arXiv2023

The Spectrum of Low-$p_T$ $J/ψ$ in Heavy-Ion Collisions in a Statistical Two-Body Fractal Model

We establish a statistical two-body fractal (STF) model to study the spectrum of $J/ψ$. $J/ψ$ serves as a reliable probe in heavy-ion collisions. The distribution of $J/ψ$ in hadron gas is influenced by flow, quantum and strong interaction effects. Previous models have predominantly focused on one or two of these effects while neglecting the others, resulting in the inclusion of unconsidered effects in the fitted parameters. Here, we study the issue from a new point of view by analyzing the fact that all three effects induce a self-similarity structure, involving a $J/ψ$-$π$ two-meson state and a $J/ψ$, $π$ two-quark state, respectively. We introduce modification factor $q_{TBS}$ and $q_2$ into the probability and entropy of charmonium. $q_{TBS}$ denotes the modification of self-similarity on $J/ψ$, $q_2$ denotes that of self-similarity and strong interaction between \emph{c }and $\bar{c}$ on quarks. By solving the probability and entropy equations, we derive the values of $q_{TBS}$ and $q_2$ at various collision energies and centralities. Substituting the value of $q_{TBS}$ into distribution function, we successfully obtain the transverse momentum spectrum of low-$p_T$ $J/ψ$, which demonstrates good agreement with experimental data. The STF model can be employed to investigate other mesons and resonance states.

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arXiv2021

Effect of relaxation time on the squeezed correlations of bosons for evolution sources in relativistic heavy-ion collisions

Squeezed back-to-back correlation (SBBC) of a boson-antiboson pair is sensitive to the time distribution of the particle-emitting source, and the SBBC function for an evolving source is expected to be affected by the relaxation time of the system. In this paper, we investigate the effect of relaxation time on the SBBC function. We put forth a method to calculate the SBBC function with relaxation-time modification for evolving sources. The SBBC functions of $D^0\!{\bar D}^0$ in relativistic heavy-ion collisions are investigated by using a hydrodynamic model. It is found that the relaxation time reduces the amplitudes of the SBBC functions. This change becomes serious for a long relaxation time and large initial relative deviations of the chaotic and squeezed amplitudes from their equilibrium values, respectively, in the temporal steps.

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arXiv2020

Analyses of multi-pion Bose-Einstein correlations for granular sources with coherent pion-emission droplets

The ALICE Collaboration measure the three- and four-pion Bose-Einstein correlations (BECs) in Pb-Pb collisions at the Large Hadron Collider (LHC). It is speculated that the significant suppressions of multi-pion BECs are due to a considerable degree of coherent pion emission in the collisions. In this paper, we study the multi-pion BEC functions in a granular source model with coherent pion-emission droplets. We find that the intercepts of multi-pion correlation functions at the relative momenta near zero are sensitive to droplet number in the granular source. They decrease with decreasing droplet number. The three-pion correlation functions for the evolving granular sources with momentum-dependent partially coherent pion-emission droplets are in basic agreement with the experimental data in Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV at the LHC. However, the model results of four-pion correlation function are inconsistent with the experimental data. The investigations of the normalized multi-pion correlation functions of the granular sources indicate that there is an interesting enhancement of the normalized four-pion correlation function in moderate relative-momentum region.

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arXiv2020

Long-range azimuthal correlations for partially coherent pion emission in proton-proton collisions

In this paper, we investigate the influence of coherent pion emission on long-range azimuthal correlations in relativistic proton-proton collisions. We study the pion momentum distribution for a coherent source with both transverse and Bjorken longitudinal expansions, and calculate the two-particle correlation function $C(Δη,Δϕ)$. A "ridge" structure is observed in the correlation function $C(Δη,Δϕ)$ of the coherent pion emission, whether the coherent source is expanding or static. The onset of this long-range azimuthal correlation can be traced back to the asymmetric initial transverse profile of the coherent source, owing to the interference in coherent emission. We further construct a partially coherent pion-emitting source by incorporating a chaotic emission component. From the experimental data of the two-pion Hanbury-Brown-Twiss correlations in pp collisions at $\sqrt{s}\!=\!7\,$TeV, we extract a coherent fraction of pion emission, which increases with increasing charged-particle multiplicity, as an input of the partially coherent source model. The ridge structure is observed in the correlation function $C(Δη,Δϕ)$ for the partially coherent source. The correlation becomes stronger at higher multiplicities because of the larger degrees of coherence. The results in this work are meaningful for fully understanding the collectivity in the small system of pp collisions.

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arXiv2019

Normalized multi-pion Hanbury Brown and Twiss correlation functions of pion-emitting sources with Bose-Einstein condensation

Recently, the ALICE collaboration analyzed the three- and four-pion Hanbury Brown-Twiss (HBT) correlations in Pb-Pb collisions at the Large Hadron Collider (LHC). The measured suppressions of three- and four-pion correlations may originate from a substantial coherence of the particle-emitting sources. In this work we investigate the normalized three- and four-pion HBT correlation functions for evolving pion gas (EPG) sources with Bose-Einstein condensation. We find that the intercepts of the normalized correlation functions at zero relative momentum are sensitive to source condensation and particle momentum. The normalized correlation functions in low average-momentum regions of three and four pions decrease with decreasing temperature and increasing particle number of the source, indicating a dependence of the normalized correlation functions on source condensation. However, this dependence becomes weak in an intermediate average-momentum region because particles with high momenta are likely emitted from excited states incoherently in the EPG model, even if the source has a considerable condensation fraction. For a wide momentum range, the normalized correlation functions for low source temperatures are enhanced at larger relative momenta because of a rapid increase of two-pion chaoticity parameter with increasing particle momentum. We hope the significant enhancement of the normalized four-pion correlation function at high relative momentum will be identified through future analyses of experimental data.

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arXiv2019

Influence of in-medium mass width on Hanbury Brown-Twiss correlation strength

The interactions of particles with medium may lead to a nonzero in-medium mass width of the particles and cause them to have different masses in the medium. In this letter, we investigate the influence of the in-medium mass width on the strength of Hanbury Brown-Twiss (HBT) correlation in high-energy heavy-ion collisions. It is found that the strength decreases with in-medium mass width of identical bosons. This influence are more significant for the boson with heavier mass and decreases with increasing particle momentum.

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arXiv2019

Squeezed back-to-back correlations of bosons with nonzero widths in relativistic heavy-ion collisions

We derive the formulas for calculating the squeezed back-to-back correlation (SBBC) between a boson and antiboson with nonzero width produced in relativistic heavy-ion collisions. The SBBCs of $D^0$ and $ϕ$ mesons with finite in-medium widths are studied. We find that the finite width can change the pattern of the SBBC function of $D^0{\bar D}^0$ with respect to mass. However, the SBBC function of $ϕϕ$ is insensitive to the width. In the high-particle-momentum region, the SBBC function of $ϕϕ$ increases with particle momentum rapidly and can exceed that of $D^0{\bar D}^0$ whether the width is nonzero or not.

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arXiv2019

Squeezed back-to-back correlation between bosons and antibosons with different in-medium masses in high-energy heavy-ion collisions

We derive the formulas of the squeezed back-to-back correlation (SBBC) between a boson and antiboson with different in-medium masses in high-energy heavy-ion collisions. The influence of the in-medium mass difference between a boson and antiboson on the SBBC is investigated. We calculate the SBBC functions of $D$-meson pairs for the hydrodynamic sources described by the VISH2+1 code for Au+Au collisions at $\sqrt{s_{NN}} =200$~GeV. Our results indicate that the SBBC strengths of $D^+D^-$ and $D^0{\bar D}^0$ are different if there are charge-dependent in-medium interactions.

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arXiv2018

Squeezed back-to-back correlation of $\bqD^0{\bar \bqD}^0$ in relativistic heavy-ion collisions

We investigate the squeezed back-to-back correlation (BBC) of $D^0\!{\bar D}^0$ in relativistic heavy-ion collisions, using the in-medium mass modification calculated with a self-energy in hot pion gas and the source space-time distributions provided by the viscous hydrodynamic code VISH2+1. It is found that the BBC of $D^0\!{\bar D}^0$ is significant in peripheral Au+Au collisions at the RHIC energy. A possible way to detect the BBC in experiment is presented.

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arXiv2018

Analyses of multi-pion Hanbury-Brown-Twiss correlations for the pion-emitting sources with Bose-Einstein condensation

We calculate the three- and four-particle correlations of identical pions in an evolving pion gas (EPG) model with Bose-Einstein condensation. The multi-pion correlation functions in the EPG model are analyzed in different momentum intervals and compared with the experimental data for Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV. It is found that the multi-pion correlation functions and cumulant correlation functions are sensitive to the condensation fraction of the EPG sources in the low average transverse-momentum intervals of the three and four pions. The model results of the multi-pion correlations are consistent with the experimental data in a considerable degree, which gives a source condensation fraction between 16~--~47\%.

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arXiv2018

Deterministic transfer of an unknown qutrit state assisted by the low-Q microwave resonators

Qutrits (i.e., three-level quantum systems) can be used to achieve many quantum information and communication tasks due to their large Hilbert spaces. In this work, we propose a scheme to transfer an unknown quantum state between two flux qutrits coupled to two superconducting coplanar waveguide resonators. The quantum state transfer can be deterministically achieved without measurements. Because resonator photons are virtually excited during the operation time, the decoherences caused by the resonator decay and the unwanted inter-resonator crosstalk are greatly suppressed. Moreover, our approach can be adapted to other solid-state qutrits coupled to circuit resonators. Numerical simulations show that the high-fidelity transfer of quantum state between the two qutrits is feasible with current circuit QED technology.

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arXiv2018

One-step implementation of a hybrid Fredkin gate with quantum memories and single superconducting qubit in circuit QED and its applications

In a recent remarkable experiment [R. B. Patel et al., Science advances 2, e1501531 (2016)], a 3-qubit quantum Fredkin (i.e., controlled-SWAP) gate was demonstrated by using linear optics. Here we propose a simple experimental scheme by utilizing the dispersive interaction in superconducting quantum circuit to implement a hybrid Fredkin gate with a superconducting flux qubit as the control qubit and two separated quantum memories as the target qudits. The quantum memories considered here are prepared by the superconducting coplanar waveguide resonators or nitrogen-vacancy center ensembles. In particular, it is shown that this Fredkin gate can be realized using a single-step operation and more importantly, each target qudit can be in an arbitrary state with arbitrary degrees of freedom. Furthermore, we show that this experimental scheme has many potential applications in quantum computation and quantum information processing such as generating arbitrary entangled states (discrete-variable states or continuous-variable states) of the two memories, measuring the fidelity and the entanglement between the two memories. With state-of-the-art circuit QED technology, the numerical simulation is performed to demonstrate that two-memory NOON states, entangled coherent states, and entangled cat states can be efficiently synthesized.

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arXiv2017

Pion transverse-momentum spectrum and elliptic anisotropy of partially coherent source

In this letter, we study the pion momentum distribution of a coherent source and investigate the influences of coherent emission on the pion transverse-momentum ($p_T$) spectrum and elliptic anisotropy. With a partially coherent source, constructed by a conventional viscous hydrodynamics model (chaotic part) and a parameterized expanding coherent source model, we reproduce the pion $p_T$ spectrum and elliptic anisotropy coefficient $v_2(p_T)$ in the peripheral Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV. It is found that the influences of coherent emission on the pion $p_T$ spectrum and $v_2(p_T)$ are related to the initial size and shape of the coherent source, largely due to the interference effect. However, the effect of source dynamical evolution on coherent emission is relatively small. The results of the partially coherent source with 33% coherent emission and 67% chaotic emission are consistent with the experimental measurements of the pion $p_T$ spectrum, $v_2(p_T)$, and especially four-pion Bose-Einstein correlations.

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arXiv2017

Squeezed back-to-back correlations of $ϕϕ$ in Au+Au and d+Au collisions at the Relativistic Heavy Ion Collider energies

We investigate the squeezed back-to-back correlations (BBC) of $ϕϕ$, caused by the mass modification of the particles in the source medium, in the heavy-ion collisions of Au+Au and d+Au at the Relativistic Heavy Ion Collider (RHIC) energies. The BBC functions are calculated using the modified masses extracted from experimental data and the source space-time distributions provided by the viscous hydrodynamic code VISH2+1. Our investigations indicate that the BBC of $ϕϕ$ may perhaps be observed in the collisions of d+Au and the peripheral collisions of Au+Au at the RHIC. We suggest to measure the BBC experimentally for understanding the mass modifications of the $ϕ$ meson in the collisions.

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arXiv2017

Pion transverse-momentum spectrum, elliptic flow, and Hanbury-Brown-Twiss interferometry in a viscous granular source model

We examine the evolution of quark-gluon plasma (QGP) droplets with viscous hydrodynamics and analyze the pion transverse-momentum spectrum, elliptic flow, and Hanbury-Brown-Twiss (HBT) interferometry in a granular source model consisting of viscous QGP droplets. The shear viscosity of the QGP droplet speeds up and slows down the droplet evolution in the central and peripheral regions of the droplet, respectively. The effect of the bulk viscosity on the evolution is negligible. Although there are viscous effects on the droplet evolution, the pion momentum spectrum and elliptic flow change little for granular sources with and without viscosity. On the other hand, the influence of viscosity on HBT radius $R_{\rm out}$ is considerable. It makes $R_{\rm out}$ decrease in the granular source model. We determine the model parameters of granular sources using the experimental data of pion transverse-momentum spectrum, elliptic flow, and HBT radii together, and investigate the effects of viscosity on the model parameters. The results indicate that the granular source model may reproduce the experimental data of pion transverse-momentum spectrum, elliptic flow, and HBT radii in heavy-ion collisions of Au-Au at $\sqrt{s_{NN}}=200$ GeV and Pb-Pb at $\sqrt{s_{NN}}=2.76$ TeV in different centrality intervals. The viscosity of the droplet leads to an increase in the initial droplet radius and a decrease of the source shell parameter in the granular source model.

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arXiv2016

Predictions for squeezed back-to-back correlations of $ϕϕ$ and $K^+K^-$ in high-energy heavy-ion collisions by event-by-event hydrodynamics

We calculate the squeezed back-to-back correlation (BBC) functions of $ϕϕ$ and $K^+K^-$ for heavy-ion collisions at RHIC and LHC energies, using ($2+1$)-dimensional hydrodynamics with fluctuating initial conditions. The BBC functions averaged over event-by-event calculations for many events for the hydrodynamic sources are smoothed as a function of the particle momentum. For heavy-ion collisions of Au+Au at $\sqrt{s_{NN}}=200$ GeV, the BBC functions are larger than those for collisions of Pb+Pb at $\sqrt{s_{NN}}=2.76$ TeV. The BBC of $ϕϕ$ may possibly be observed in peripheral collisions at the RHIC and LHC energies. It is large for the smaller sources of Cu+Cu collisions at $\sqrt{s_{NN}}=200$ GeV.

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