arXiv subjects

Pengfei Zhuang

Publications and source records attributed to Pengfei Zhuang.

At least 19 recordsLinked to original sources

arXiv2026

Color screening versus thermal decay as the mechanism of $Υ$ suppression in high energy nuclear collisions

To clearly identify the mechanism behind the suppression of heavy quarkonium in relativistic heavy-ion collisions, we study $Υ$ production at RHIC energies by solving its transport equation driven solely by the suppression rates. By calculating the nuclear modification factor and comparing it with experimental data, we find that the sudden suppression governed by the color-screening temperature cannot simultaneously describe both the ground and excited states of the $Υ$, whereas the continuous suppression induced by thermal decay successfully reproduces all the $Υ$ measurements. This provides strong evidence that inelastic scatterings with thermal partons, rather than color screening, dominate quarkonium suppression in heavy-ion collisions.

hep-ph↗

arXiv2026

Applicability of kinetic theory in strongly coupled thermal quantum systems

In this work, we construct one-dimensional interacting lattice spinor theories with discretization in momentum space. We focus on strongly interacting Schwinger and Nambu--Jona-Lasinio models and perform ab-initio calculation of their single-particle and two-particle momentum distribution functions at finite temperature. We observe, at low temperature, high-momentum tail in single-particle and two particle distribution which reveals relative momentum in fermion-antifermion boundstates, as well as quasi-free spinor gases behavior at high temperature. The non-vanishing connected four-momentum function reveals the quantum coherence in momentum space under thermal equilibrium of the system and indicate the single particle correlation would remember more microscopic details within a thermal system. Overall, for a high-enough temperature at which the thermal kinetic energy comparable with the interaction, we observe that the two-particle correlation is subdominant compared to the single particle distributions, which indicates the applicability of kinetic theory.

nucl-th↗

arXiv2026

D-meson production via sequential hadronization in high-energy nuclear collisions

Heavy flavor production serves as an ideal probe of the hadronization mechanism of the quark-gluon plasma created in relativistic heavy ion collisions. We study charm-quark hadronization using Langevin transport in the medium together with a sequential coalescence model. Since $D_s$ forms earlier than $D^0$, as obtained from the Dirac equation with an in-medium potential extracted from lattice QCD, the $D_s$ elliptic flow $v_2$ is smaller than the $D^0$ $v_2$ in the intermediate-$p_T$ region, in good agreement with the recent ALICE data. Incorporating sequential coalescence, charm-quark number conservation, and strangeness enhancement predicts a peak in the yield ratio $D_s/D^0$ at low $p_T$, which can be tested in future heavy-ion collisions.

nucl-th↗

arXiv2026

Stationary States for Fermions in an External Electric Field

We present a relativistic analysis of fermions in an external electric field by non-perturbatively solving the Dirac equation with a static gauge. Different from the magnetic field effect, the fermion wave function in an electric field oscillates asymptotically, which results in the absence of bound states in an infinite system. For a confined fermion, the confinement is gradually canceled by the electric field, and the fermion becomes deconfined when the electric coupling is stronger than the confinement coupling. However, a fermion in an electric field can be confined to a finite system by applying the MIT bag boundary condition, namely, the disappearing normal component of the probability current at the boundary. The solutions obtained can serve as a basis for calculating dynamical processes in the presence of a strong electric field, such as those occurring in the early stage of relativistic heavy-ion collisions, where an extremely strong electric field is expected to be generated.

nucl-th↗

arXiv2026

Rotation induced color confinement

The rotation effect on the QCD properties is an open question. We study the dynamic gluon mass in a dense QCD matter, the rotation is introduced by taking a covariant transformation between the flat and curved spaces. The law of causality which restricts the rotation strength of the system is carefully considered in the calculation. we find that the rotation effect is not monotonous. Overall, it behaves like an anti-screening effect, reflecting in the decreasing gluon mass, but the strength changes with the rotation. For a QCD matter with low baryon density, the screening effect in the flat space can be completely canceled by the rotation, and gluons are confined in a strongly rotating matter. When the rotation is extremely high, the matter approaches to a weakly interacting gas.

hep-ph↗

arXiv2025

Searching for True Muonium in Relativistic Heavy Ion Collisions

We investigate the production of the as-yet-undetected true muonium within the quark-gluon plasma formed in relativistic heavy-ion collisions, employing a relativistic Boltzmann transport framework coupled to viscous hydrodynamic simulations. The obtained effective cross sections for central collisions are 1.23~$μb$ in AuAu collisions with $\sqrt{s_{\rm NN}}=200$~GeV and 14.2~$μb$ in PbPb collisions with $\sqrt{s_{\rm NN}}=5.02$~TeV, resulting in a yield of $\mathcal{O}(10^4)$ and $\mathcal{O}(10^5)$ true muonium per billion $AA$ collisions at RHIC and the LHC, respectively. This establishes heavy-ion collisions as a promising process for detecting true muonium.

nucl-th↗

arXiv2025

Suppressed Drell-Yan process by an external magnetic field

The strongest electromagnetic fields in nature are created in high energy nuclear collisions and expected to change the dynamic scattering processes in the early stage. The magnetic field effect on the Drell-Yan process is investigated in this work. The single photon decay into quark pairs and lepton pairs in an external magnetic field leads to a significant Drell-Yan suppression in low and intermediate invariant mass region. The calculation up to the Landau level $n-1$ is complete in the energy region $s<2/3n(eB)$, and the enlarged phase space at higher landau levels may enhance the dilepton spectrum in the high mass region.

hep-ph↗

arXiv2024

Gluon decay into heavy quark pair under a strong magnetic field

Due to the extreme large magnetic field produced in the initial stage of non-central heavy-ion collision, the dynamical process of gluon decay into heavy quark pair will take place under an external field rather than in vacuum. Unlike in the vacuum case, where the process is forbidden by energy momentum conservation, under the external field, a process emerges considering the background energy which recovers the conservation. We calculate the gluon decay rate at leading order under a uniform magnetic field.

hep-ph↗

arXiv2024

$B_c$ enhancement with non-thermalized bottom quarks in nuclear collisions at Large Hadron Collider

We study $B_c$ production in high-energy nuclear collisions in a transport approach with dissociation and regeneration at finite temperatures. Due to the rare production in p+p collisions and the strong combination of uncorrelated $c$ and $\bar b$ quarks in the quark-gluon plasma, the $B_c$ yield is significantly enhanced in the nuclear collisions at the Large Hadron Collider. Moreover, the centrality and momentum-dependent yield of $B_c$ sensitively reflect the thermalization degree of bottom quarks. And the newly observed experimental data favors a far from the thermal bottom quark distribution in the quark-gluon plasma.

hep-ph↗

arXiv2024

Controlling mass and energy diffusion with metamaterials

Diffusion driven by temperature or concentration gradients is a fundamental mechanism of energy and mass transport, which inherently differs from wave propagation in both physical foundations and application prospects. Compared with conventional schemes, metamaterials provide an unprecedented potential for governing diffusion processes, based on emerging theories like the transformation and the scattering cancellation theory, which enormously expanded the original concepts and suggest innovative metamaterial-based devices. We hereby use the term "diffusionics" to generalize these remarkable achievements in various energy (e.g., heat) and mass (e.g., particles and plasmas) diffusion systems. For clarity, we categorize the numerous studies appeared during the last decade by diffusion field (i.e., heat, particles, and plasmas) and discuss them from three different perspectives: the theoretical perspective, to detail how the transformation principle is applied to each diffusion field; the application perspective, to introduce various intriguing metamaterial-based devices, such as cloaks and radiative coolers; and the physics perspective, to connect with concepts of recent concern, such as non-Hermitian topology, nonreciprocal transport, and spatiotemporal modulation. We also discuss the possibility of controlling diffusion processes beyond metamaterials. Finally, we point out several future directions for diffusion metamaterial research, including the integration with artificial intelligence and topology concepts.

physics.app-ph↗

arXiv2024

Heavy flavor production under a strong magnetic field

The magnetic field created in high energy nuclear collisions will affect the dynamical processes in the QCD medium, especially the heavy quark production that happens in the initial stage of the collisions. We calculate in a strong magnetic field the heavy quark production cross section for the elementary process gg {\rightarrow} Q{\bar Q} at leading order and the corresponding transverse momentum distribution in nucleus-nucleus collisions. In comparison to the QED process, the heavy quark production is dominated by the unique QCD channel with gluon self-interaction. Due to the dimension reduction of quark phase space in a strong magnetic field, the production is concentrated in a very narrow energy region above the threshold. Since the translation invariance is broken, the production becomes anisotropic in magnetic field.

hep-ph↗

arXiv2024

Reconfigurable Three-Dimensional Thermal Dome

Thermal metamaterial represents a groundbreaking approach to control heat conduction, and, as a crucial component, thermal invisibility is of utmost importance for heat management. Despite the flourishing development of thermal invisibility schemes, they still face two limitations in practical applications. First, objects are typically completely enclosed in traditional cloaks, making them difficult to use and unsuitable for objects with heat sources. Second, although some theoretical proposals have been put forth to change the thermal conductivity of materials to achieve dynamic invisibility, their designs are complex and rigid, making them unsuitable for large-scale use in real three-dimensional spaces. Here, we propose a concept of a thermal dome to achieve three-dimensional invisibility. Our scheme includes an open functional area, greatly enhancing its usability and applicability. It features a reconfigurable structure, constructed with simple isotropic natural materials, making it suitable for dynamic requirements. The performance of our reconfigurable thermal dome has been confirmed through simulations and experiments, consistent with the theory. The introduction of this concept can greatly advance the development of thermal invisibility technology from theory to engineering and provide inspiration for other physical domains, such as direct current electric fields and magnetic fields.

physics.app-ph↗

arXiv2024

Cooperative near- and far-field thermal management via diffusive superimposed dipoles

Active metadevices with external excitations exhibit significant potential for advanced heat regulation. Nonetheless, conventional inputs, like heating/cooling and introducing convection by rotating plate, display inherent limitations. One is the only focus on far-field control to eliminate temperature distortion in the background while neglecting near-field regulation in the functional region. Another is lacking adaptability due to complex devices like thermoelectric modules and stepping motors. To tackle these challenges, the concept of diffusive superimposed dipoles characterized by orthogonal thermal dipole moments is proposed. Cooperative near- and far-field regulation of temperature fields is achieved by designing superimposed dipole moments, enabling transparency and cloaking functionalities. Simulation and experiment outcomes affirm the efficacy of this adaptive thermal field control technique, even when interface thermal resistance is taken into account. Adaptivity stems from dipole moment decomposability, allowing metadevices to operate in various heat flux directions and background thermal conductivity. These findings could pave the way for cooperative and adaptive thermal management and hold potential applications in other Laplace fields, including direct current and hydrodynamics.

physics.app-ph↗

arXiv2023

$U_A(1)$ symmetry restoration at high baryon density

We study the relation between chiral and $U_A(1)$ symmetries in the quark-meson model. Although quarks and mesons are described in mean field approximation, the topological susceptibility characterizing the $U_A(1)$ breaking comprises two components: one controlled by the condensate and the other by the meson fluctuation. The $U_A(1)$ restoration is governed by the competition of these components. In a hot medium, the condensates melt. However, the fluctuation is enhanced. Therefore, the $U_A(1)$ symmetry cannot be solely restored via the temperature effect. Nevertheless, the baryon density reduces the condensates and fluctuation, and thereby, the $U_A(1)$ symmetry can only be restored in a dense or dense and hot medium. The strange condensate plays a weak role in the susceptibility, and the chiral and $U_A(1)$ symmetry restorations occur almost at the same critical point.

hep-ph↗

arXiv2023

Resonant screening in dense and magnetized QCD matter

We calculate the Debye screening mass in thermal, dense and magnetized QCD matter in the frame of resummed perturbation theory. In the limit of zero temperature, when the Landau energy level and Fermi surface of quarks match each other $μ_q^2=2n|qB|$, where $q$, $μ_q$ and $B$ are respectively the quark electric charge, chemical potential and external magnetic field, the screening mass diverges and the system is in the state of weakly interacting parton gas, which is very different from the known result of strongly interacting quark-gluon plasma at high temperature. The divergence disappears in thermal medium, but the screening mass oscillates with clear peaks at the matched magnetic field.

hep-ph↗

arXiv2023

Quantum color screening in external magnetic field

We calculate color screening mass in a thermalized and magnetized QCD matter in the frame of loop resummation theory without restriction to the magnetic field strength. Our full calculation covers the often used approximations for weak magnetic field at high temperature and strong magnetic field at low temperature. We find that while the magnetic field created in heavy ion collisions at RHIC and LHC energies is probably the strongest one in nature, its effect on the QCD matter is still weaker in comparison with the high temperature of the fireball, and therefore can safely be treated as a perturbation.

hep-ph↗

arXiv2022

Heavy-quark potential in Gribov-Zwanziger approach around deconfinement phase transition

The interaction potential between a pair of heavy quarks is calculated with resummed perturbation method in Gribov-Zwanziger approach at finite temperature. The resummed loop correction makes the potential complex. While the real part is, as expected, screened and becomes short-ranged in hot medium, the strength of the imaginary part increases with temperature and is comparable with the real part, which is very different from the previous calculation in HTL approach. This means that, both the color screening and Landau damping play important role in the dissociation of heavy flavor hadrons in hot medium.

hep-ph↗

arXiv2022

Casimir effect in kinetic theory

We study Casimir effect in equilibrium and non-equilibrium photon gas in the frame of quantum kinetic theory for $U(1)$ gauge field. We derive first the transport, constraint and gauge fixing equations for the photon number distribution from Maxwell's equations, and then calculate the energy variation and Casimir force for a finite system by considering boundary condition on the surface of the system. The Casimir force in vacuum is suppressed by the thermal motion of photons in equilibrium state, when considering two adiabatic plates. In non-equilibrium state, the photon induced Casimir force oscillates and decays with time and finally disappears.

quant-ph↗