arXiv subjects

Peng-Ming Zhang

Publications and source records attributed to Peng-Ming Zhang.

At least 19 recordsLinked to original sources

arXiv2026

Quantum dominance of coherent bremsstrahlung in $^{124}$Sn + $^{124}$Sn scattering at 25 MeV/u

We present quantum-mechanical calculations of bremsstrahlung in the $^{124}$Sn + $^{124}$Sn at 25 MeV/u reproducing the measured photon spectrum over the full energy range. For the first time, we quantitatively determine the incoherent-to-coherent ratio in the photon spectrum. This ratio is extremely small, ranging from $10^{-11}$ to $10^{-4}$, which demonstrates that coherent emission dominates throughout the measured energy range. This behavior is in sharp contrast to proton-nucleus scattering, where incoherent emission dominates because of the leading role of nucleon magnetic moments. This contrast is illustrated by the TAPS Collaboration data for $p + ^{197}{\rm Au}$ collisions at a proton beam energy of 190 MeV, where the corresponding ratio reaches $10^{3}$-$10^{5}$. We find that incoherent-to-coherent ratios explain the difference between the two spectra in unified picture: (1) In proton--nucleus scattering, the spectrum contains a pronounced hump, (2) In $^{124}$Sn + $^{124}$Sn scattering, the spectrum decreases monotonically and has a nearly logarithmic shape. Our results identify a previously unexplored quantum regime of bremsstrahlung emission in nuclear reactions and open a new route for studying coherent effects in heavy-ion collisions.

nucl-th↗

arXiv2025

Globally defined Carroll symmetry of gravitational waves

The local Carroll symmetry of a gravitational wave found in Baldwin-Jeffery-Rosen coordinates is extended to a globally defined one by switching to Brinkmann coordinates. Two independent globally defined solutions of a Sturm-Liouville equation allow us to describe both the symmetries (translations and Carroll boosts) and the geodesic motions. One of them satisfies particular initial conditions which imply zero initial momentum, while the other does not. Pure displacement arises when the latter is turned off by requiring the momentum to vanish and when the wave parameters take, in addition, some particular values which correspond to having an integer half-wave number. The relation to the Schwarzian derivative is highlighted. We illustrate our general statements by the P\"oschl-Teller profile.

gr-qc↗

arXiv2025

Manifestation of quark effects in nuclei via bremsstrahlung analysis in the proton-nucleus scattering

\textbf{Background} (1) The incoherent emission of photons is dominant comparing to coherent one in proton-nucleus scattering. The incoherent bremsstrahlung is very sensitive to the magnetic moments of nucleons in nuclei. (2) According to the quark-meson coupling (QMC) model, the nucleon magnetic moments in nuclei are enhanced relative to those in vacuum, originating from the quark structure of nucleons. \textbf{Purpose} Investigate possibilities of observing quark effects in nuclei by the analysis of bremsstrahlung in nuclear reactions. \textbf{Methods} Analyse the bremsstrahlung cross sections with established model in proton-nucleus scattering, by extending with inclusion of in-medium modified nucleon magnetic moments in nuclei by the QMC model. \textbf{Results} (1) After calibrating the model without the quark effects for experimental data (TAPS Collaboration data for $p + \isotope[197]{Au}$), we calculate the cross sections and observe the slight difference between the spectra for models with and without quark effects. Such result is found for the first time, confirming possibilities of observing the quark effects in the spectra of bremsstrahlung. (2) As found, quark effects are not enough to be observed in middle and heavy nuclei, as they have dominant incoherent contributions. (3) \isotope[18]{C} has minimal incoherent contribution concerning other carbon isotopes, where the quark effects should be minimal. In ratios between the spectra for \isotope[18]{C} and \isotope[12]{C} with and without the quark effects the difference is clearly observed. \textbf{Conclusions} We establish the new physical observable for the quark effects in nuclei in the bremsstrahlung accompanied in the nuclear reactions, which can be measured. The present suggestion is for the first time in both theoretically and experimentally to study the quark effects in nuclei via the bremsstrahlung.

nucl-th↗

arXiv2025

Kerner equation for motion in a non-Abelian gauge field

The equations of motion of an isospin-carrying particle in a Yang-Mills and gravitational field were first proposed in 1968 by Kerner, who considered geodesics in a Kaluza-Klein-type framework. Two years later the flat space Kerner equations were completed by considering also the motion of the isospin by Wong, who used a field-theoretical approach. Their groundbreaking work was then followed by a long series of rediscoveries whose history is reviewed. The concept of isospin charge and the physical meaning of its motion are discussed. Conserved quantities are studied for Wu-Yang monopoles and for diatomic molecules by using van Holten's algorithm.

math-ph↗

arXiv2025

Isospin precession in non-Abelian Aharonov-Bohm scattering

The concept of pseudoclassical isospin is illustrated by the non-Abelian Aharonov-Bohm effect proposed by Wu and Yang in 1975. The spatial motion is free however the isospin precesses when the enclosed magnetic flux and the incoming particle's isosopin are not parallel. The non-Abelian phase factor $\mathfrak{F}$ of Wu and Yang acts on the isospin as an S-matrix. The scattering becomes side-independent when the enclosed flux is quantized, $Φ_N=NΦ_0$ with $N$ an integer. The gauge group $SU(2)$ is an internal symmetry and generates conserved charges only when the flux is quantized, which then splits into two series: for $N=2k$ $SU(2)$ acts trivially but for $N=1+2k$ the implementation is twisted. The orbital and the internal angular momenta are separately conserved. The double rotational symmetry is broken to $SO(2)\times SO(2)$ when $N$ odd. For unquantized flux there are no internal symmetries, the charge is not conserved and protons can be turned into neutrons.

hep-th↗

arXiv2025

Anyonic spin-Hall effect on the Black Hole horizon

Using the fact that the horizon of black holes is a Carroll manifold, we show that an ``exotic photon'' i.e. a particle without mass and charge but with anyonic spin, magnetic moment and ``exotic'' charges associated with the 2-parameter central extension of the 2-dimensional Carroll group moves on the horizon of a Kerr-Newman Black Hole consistently with the Hall law.

gr-qc↗

arXiv2025

The Hall effects of vortex light in optical materials

For light, its spin can be independent of the spatial distribution of its wave function, whereas its intrinsic orbital angular momentum does depend on this distribution. This difference suggests that the spin Hall effect might differ from the orbital Hall effect as light propagates through optical materials. In this paper, we model optical materials as curved space-time and investigate light propagation in two specific materials by solving the covariant Maxwell equations. We find that the trajectory of light with spin $σ$ and intrinsic orbital angular momentum $\ell$ deviates from that of light without angular momentum ($σ=0$ and $\ell=0$) by an angle $θ_{σ,\ell} \propto 2σ+\ell$. In particular, the contribution of spin $σ$ to angle $θ_{σ,\ell}$ is twice that of the intrinsic orbital angular momentum $\ell$, highlighting their differing effects on light propagation in optical materials. Furthermore, this angle $θ_{σ,\ell}$ could potentially be observed experimentally, enhancing our understanding of the role of angular momentum in light propagation.

physics.optics↗

arXiv2024

Effective ray equations for vortex light and their application in an optical waveguide

Beyond its spin, light can also carry intrinsic orbital angular momentum (IOAM), termed as vortex light. In this study, we derive effective ray equations for vortex light by applying the WKB approximation to the covariant Maxwell equations. According to these equations, the propagation of vortex light can be significantly affected by its IOAM, as suggested by numerous studies. To examine the effects of IOAM, we solve the effective ray equations for vortex light and investigate its ray trajectory within a specific optical waveguide. Our findings indicate that the ray trajectory of vortex light exhibits a divergence perpendicular to the normal propagation plane, akin to the spin Hall effect in light. This divergence, termed as the orbital Hall effect, stems from the IOAM of the light. In this study, the effective ray equations are derived by modeling the interaction between light and media as light's free fall in a curved spacetime. Therefore, observing the orbital Hall effect could not only enhance our understanding of light's spin and IOAM, but also offer novel insights into the coupling between light and gravitational fields.

gr-qc↗

arXiv2024

Gravitational spin Hall effect of electrons in Schwarzschild metric

In this study, we derive the non-relativistic Hamiltonian for electrons within the Schwarzschild metric from covariant Dirac equations, using both the weak field approximation and the Foldy-Wouthuysen transformation. This Hamiltonian incorporates a gravitational spin-orbit coupling term, resulting in the gravitational spin Hall effect (SHE), which separates electrons by their spin. By solving the Schrödinger equation for these electrons, we investigate the gravitational SHE as they orbit a non-rotating gravitational source. Our findings reveal that the spin-dependent separation of electrons increases in proportion to their orbital periods, significantly improving the detectability of gravitational SHE. Specifically, for electrons in a low Earth orbit, the separation is estimated to be $3.0\times 10^{-12}\, \text{m}$ annually. These results indicate the practicality of detecting the gravitational SHE in electrons orbiting Earth, especially with prolonged orbital durations, underscoring the potential for quantum test of the Weak Equivalence Principle.

gr-qc↗

arXiv2024

Gravitational orbital Hall effect of vortex light in Lense-Thirring metric

Vortex light, characterized by an intrinsic orbital angular momentum aligned with its propagation direction, is described through vortex electromagnetic waves. Similar to the gravitational spin Hall effect (SHE), vortex light is expected to exhibit intrinsic orbital angular momentum dependent trajectories and deviations from the null geodesic plane when propagating through a gravitational field, a phenomenon termed the gravitational orbital Hall effect (OHE). In this work, we model the vortex light as vortex Laguerre-Gaussian electromagnetic wave packets and analyze its motion by solving covariant Maxwell equations within the Lense-Thirring metric. Our findings reveal that the trajectory of vortex light with an intrinsic orbital angular momentum deviates from the null geodesic in two ways. It deviates both perpendicular to, and within, the null geodesic plane. This behavior contrasts with the gravitational SHE, where spin-polarized light primarily deviates perpendicular to the null geodesic plane. Moreover, the relationship between the deviation and intrinsic orbital angular momentum differs significantly from that between the deviation and spin. These results suggest a unique interaction between intrinsic orbital angular momentum and gravity, distinct from the spin-gravity coupling, indicating that the gravitational OHE of light might not be precisely predicted by merely substituting spin with intrinsic orbital angular momentum in the gravitational SHE of light.

gr-qc↗

arXiv2024

The motion of twisted particles in a stellar gravitational field

In this work, we explore the motion of a twisted particle possessing intrinsic orbital angular momentum (OAM) as it traverses a weak stellar gravitational field, which we approximate using a polytropic model. We disregard the spin characteristic of the twisted particle, modeling it as a massless complex twisted scalar wave packet to simplify its interaction with gravitational fields. Building on this simplification, we determine the trajectory of this twisted particle by using the center of its energy density and investigate the gravitational birefringence induced by its OAM. In a weak field approximation, we find the gravitational birefringence-OAM relationship parallels that with spin, as described by the Mathisson-Papapetrou-Dixon equations. This indicates that the gravitational birefringence induced by OAM can potentially exceed that induced by spin by several orders of magnitude, significantly enhancing its detectability. To broaden our analysis, we introduce a nonminimal coupling term, $λR|ϕ|^2$, into the Lagrangian, resulting in the modified expression $\mathcal{L}=-\frac{1}{2}\nabla _ρϕ\nabla^ρϕ^*-\frac{1}{2}λR|ϕ|^2$. This adjustment is necessitated by the quantization of the scalar field in curved spacetime. We then explore the effects of this term on the motion of the twisted particle. Our findings show that the trajectory of the twisted particle under nonminimal coupling ($λ\neq 0$) differs from that in the minimal coupling scenario ($λ=0$). Specifically, for a positive nonminimal coupling constant $λ$, the trajectory of the twisted particle is expected to deviate away from the stellar center, compared to the minimal coupling scenario.

gr-qc↗

arXiv2024

Nucleon microscopy in proton-nucleus scattering via analysis of bremsstrahlung emission: role of incoherent emission

We study electromagnetic form factors of protons in proton-nucleus scattering via analysing of experimental cross-sections of accompanying bremsstrahlung photons. A new bremsstrahlung model for proton-nucleus scattering is developed, where a main focus is given on incoherent bremsstrahlung that has not been considered previously. In analysis we choose experimental bremsstrahlung data of $p$ + $^{197}$Au scattering at proton beam energy of 190 MeV obtained by TAPS collaboration. We find the following. (1) Inclusion of incoherent emission to calculations improves agreements with experimental data essentially, contribution of incoherent bremsstrahlung is essentially larger than coherent one. (2) Inclusion of form factors of the scattered proton improves agreement with experimental data in comparison with calculations with coherent and incoherent contributions without form factors. (3) Sensitivity of model in study of form factors of the scattered proton is high. This demonstrates a new opportunity to study internal structure of protons under influence of nuclear forces in nuclear scattering.

nucl-th↗

arXiv2019

Search of cluster structure in nuclei via analysis of bremsstrahlung emission

We investigate emission of bremsstrahlung photons during scattering of $α$-particles off nuclei. For that, we construct bremsstrahlung model for $α$-nucleus scattering, where a new formalism for coherent and incoherent bremsstrahlung emissions in elastic scattering and mechanisms in inelastic scattering is added. Basing of this approach, we analyze experimental bremsstrahlung cross-sections in the scattering of $α$-particles off the \isotope[59]{Co}, \isotope[116]{Sn}, \isotope[\rm nat]{Ag} and \isotope[197]{Au} nuclei at 50 MeV of $α$-particles beam measured at the Variable Energy Cyclotron Centre, Calcutta. We observe oscillations in the calculated spectra for elastic scattering for each nucleus. But, for \isotope[59]{Co}, \isotope[116]{Sn} and \isotope[\rm nat]{Ag} we obtain good agreement between calculated coherent spectrum with incoherent contribution for elastic scattering with experimental data in the full photon energy region. For heavy nucleus \isotope[197]{Au} we find that (1) Oscillating behavior of the calculated spectrum of coherent emission in elastic scattering is in disagreement with experimental data, (2) Inclusion of incoherent emission improves description of the data, but summarized spectrum is in satisfactory agreement with the experimental data. To understand unknown modification of wave function for scattering, we add new mechanisms of inelastic scattering to calculations and extract information about unknown new amplitude of such mechanisms from experimental data analysis. This amplitude has maxima at some energies, that characterizes existence of states of the most compact structures (clusters) in nucleus-target. We explain origin of oscillations in the bremsstrahlung spectra for elastic scattering (at first time). New information about coherent and incoherent contributions is extracted for studied reactions.

nucl-th↗

arXiv2018

Nucleon microscopy in proton-nucleus scattering via analysis of bremsstrahlung emission

We investigate an idea, how to use analysis of the bremsstrahlung photons to study the internal structure of proton under nuclear reaction with nucleus. A new model is constructed to describe bremsstrahlung emission of photons which accompanies the scattering of protons off nuclei. Our bremsstrahlung formalism uses many-nucleon basis that allows to analyze coherent and incoherent bremsstrahlung emissions. As scattered proton can be under the influence of strong forces and produces the largest bremsstrahlung contribution to full spectrum, we focus on accurate determination of its quantum evolution concerning nucleus basing on quantum mechanics and scattering theory. For such a motivation, we at first time generalize Pauli equation with interacting potential describing evolution of fermion inside strong field, with including the electromagnetic form-factors of nucleon basing on DIS theory. Anomalous magnetic momenta of nucleons reinforce our motivation to develop such a formalism, starting from low energy. The full bremsstrahlung spectrum in our model (after renormalization) is dependent on form-factors of the scattered proton. For calculations, we choose the scattering of $p + ^{197}{\rm Au}$ at proton beam energy of 190~MeV, where experimental bremsstrahlung data were obtained with high accuracy. We show that the full bremsstrahlung spectrum is sensitive to the form-factors of the scattered proton. In the limit without such form-factors, we reconstruct our previous result (where internal structure of the scattered proton was not studied).

nucl-th↗

arXiv2018

What can we know about hypernuclei via analysis of bremsstrahlung photons?

We investigate possibility of emission of the bremsstrahlung photons in nuclear reactions with hypernuclei for the first time. A new model of the bremsstrahlung emission which accompanies interactions between $α$ particles and hypernuclei is constructed, where a new formalism for the magnetic momenta of nucleons and hyperon inside hypernucleus is added. For first calculations, we choose $α$ decay of the normal nucleus $^{210}{\rm Po}$ and the hypernucleus $^{211}_Λ{\rm Po}$. We find that (1) emission for the hypernucleus $^{211}_Λ{\rm Po}$ is larger than for normal nucleus $^{210}{\rm Po}$, (2) difference between these spectra is small. We propose a way how to find hypernuclei, where role of hyperon is the most essential in emission of bremsstrahlung photons during $α$ decay. As demonstration of such a property, we show that the spectra for the hypernuclei $^{107}_Λ{\rm Te}$ and $^{109}_Λ{\rm Te}$ are essentially larger than the spectra for the normal nuclei $^{106}{\rm Te}$ and $^{108}{\rm Te}$. Such a difference is explained by additional contribution of emission to the full bremsstrahlung, which is formed by magnetic moment of hyperon inside hypernucleus. The bremsstrahlung emission formed by such a mechanism, is of the magnetic type. A new formula for fast estimations of bremsstrahlung spectra for even-even hypernuclei is proposed, where role of magnetic moment of hyperon of hypernucleus in formation of the bremsstrahlung emission is shown explicitly. Such an analysis opens possibility of new experimental study of properties of hypernuclei via bremsstrahlung study.

nucl-th↗

arXiv2018

Manifestation of important role of nuclear forces in emission of photons in scattering of pions off nuclei

Bremsstrahlung of photons emitted during the scattering of $π^{+}$-mesons off nuclei is studied for the first time. Role of interactions between $π^{+}$-mesons and nuclei in the formation of the bremsstrahlung emission is analyzed in details. We discover essential contribution of emitted photons from nuclear part of Johnson-Satchler potential to the full spectrum, in contrast to the optical Woods-Saxon potential. We observe unusual essential influence of the nuclear part of both potentials on the spectrum at high photon energies. This phenomenon opens a new experimental way to study and check non-Coulomb and nuclear interactions between pions and nuclei via measurements of the emitted photons. We provide predictions of the bremsstrahlung spectra for pion scattering off $^{44}{\rm Ca}$.

nucl-th↗

arXiv2017

New quasibound states of the compound nucleus in $α$-particle capture by the nucleus

We generalize the theory of nuclear decay and capture of Gamow that is based on tunneling through the barrier and internal oscillations inside the nucleus. In our formalism an additional factor is obtained, which describes distribution of the wave function of the $α$ particle inside the nuclear region. We discover new most stable states (called quasibound states) of the compound nucleus (CN) formed during the capture of $α$ particle by the nucleus. With a simple example, we explain why these states cannot appear in traditional calculations of the $α$ capture cross sections based on monotonic penetrabilities of a barrier, but they appear in a complete description of the evolution of the CN. Our result is obtained by a complete description of the CN evolution, which has the advantages of (1) a clear picture of the formation of the CN and its disintegration, (2) a detailed quantum description of the CN, (3) tests of the calculated amplitudes based on quantum mechanics (not realized in other approaches), and (4) high accuracy of calculations (not achieved in other approaches). These peculiarities are shown with the capture reaction of $α+ ^{44}{\rm Ca}$. We predict quasibound energy levels and determine fusion probabilities for this reaction. The difference between our approach and theory of quasistationary states with complex energies applied for the $α$ capture is also discussed. We show (1) that theory does not provide calculations for the cross section of $α$ capture (according to modern models of the $α$ capture), in contrast with our formalism, and (2) these two approaches describe different states of the $α$ capture (for the same $α$-nucleus potential).

nucl-th↗

arXiv2017

Confining potential of Y-string on the lattice at finite T

The potential due to a system of three static quark (3Q) is studied using SU(3) lattice QCD at finite temperature with Polyakov loops operators. We focused our analysis on the large distance properties of the 3Q potential and found a good fit behavior to the Y-string model formula. In addition to the linearly confining term proportional to the minimal length of the Y-string, we observed that the subleading logarithmic term, which is proportional to Dedekind eta function and accounts for the Y-string's quantum fluctuations, is necessary to reproduce the quark anti-quark string tension of the corresponding mesonic system at finite temperature.

hep-lat↗