Nuclear Theory·nucl-th

Tuesday·October 1, 2024

24 papers—12 primary·12 cross-listed

01
Probing Nuclear Structure of Heavy Ions at the Large Hadron Collider
Heikki Mäntysaari🇫🇮 · Björn Schenke🇺🇸 · Chun Shen🇺🇸 · Wenbin Zhao🇺🇸
We perform high-statistics simulations to study the impacts of nuclear structure on the ratios of anisotropic flow observables in $^{208}$ Pb+ $^{208}$ Pb and $^{129}$ Xe+ $^{129}$ Xe collisions at the Large Hadron Collider. Even with $40%$ difference in atomic numbers between $^{208}$ Pb and $^{129}$ Xe nuclei, the ratios of anisotropic flow in the same centrality class between the two collision systems are strongly affected by the nuclear structure inputs in the initial state. The ratios of $v_{2} {4} / v_{2} {2}$ in these collisions are sensitive to the nuclear skin thickness of the colliding nuclei, providing indirect constraints on the nuclei's neutron skin. Our model predictions serve as a benchmark to compare with experimental measurements.
nucl-thhep-phnucl-exPRC(2024)·27 citations
02
Exploring the Diversity of Nuclear Density through Information Entropy
Wei-Hu Ma · Yu-Gang Ma
This study explores the role of information entropy in understanding nuclear density distributions, including both stable configurations and non-traditional structures such as neutron halos and $α$ -clustering. By quantifying the uncertainty and disorder inherent in nucleon distributions in nuclear many-body systems, information entropy provides a macroscopic measure of the physical properties of the system. A more dispersed and disordered density distribution results in a higher value of information entropy. This intrinsic relationship between information entropy and system complexity allows us to quantify uncertainty and disorder in nuclear structures by analyzing various geometric parameters such as nuclear radius, diffuseness, neutron skin, and cluster structural features.
nucl-thnucl-exEntropy(2024)·3 citations
03
Nucleation of baryons in relativistic hadron-nucleus collisions
A. Ergun🇹🇷 · N. Buyukcizmeci🇹🇷 · A. Kittiratpattana🇩🇪 · T. Reichert🇩🇪 · A. S. Botvina🇩🇪 · M. Bleicher🇩🇪
We suggest a new theoretical method to describe the baryon clusterization of nuclei in hadron-nucleus reactions. As an example we have explored the nuclei production in $π^{-} + C$ and $π^{-} + W$ collisions at p $_{l ab}$ =1.7 GeV by using the hybrid approach consisting of the Ultra Relativistic Quantum Dynamics Model (UrQMD) and the Statistical Multifragmentation Model (SMM). The UrQMD describes the production of new baryons, and the propagation toward the subnuclear densities with the fluctuations leading to the formation of excited baryonic clusters. The SMM describes the production of final nuclei and hypernuclei after interaction of baryons inside these clusters. We demonstrate the transverse momenta, rapidity, mass distributions and excitation energies of both primary clusters and final nuclei (including hypernuclei). The results of the UrQMD and UrQMD+SMM model calculations for different clusterization parameters are compared with the available HADES experimental data on baryon production, providing a very promising window for future research on nuclei and hypernuclei formation in these reactions.
nucl-thNPA(2025)·1 citation
04
Chebyshev Based Spectral Representations of Neutron-Star Equations of State
Lee Lindblom · Tianji Zhou
Causal parametric representations of neutron-star equations of state are constructed here using Chebyshev polynomial based spectral expansions. The accuracies of these representations are evaluated for a collection of model equations of state from a variety of nuclear-theory models and also a collection of equations of state with first- or second-order phase transitions of various sizes. These tests show that the Chebyshev based representations are convergent (even for equations of state with phase transitions) as the number of spectral basis functions is increased. This study finds that the Chebyshev based representations are generally more accurate than a previously studied power-law based spectral representation, and that pressure-based representations are generally more accurate than those based on enthalpy.
nucl-thastro-ph.HEgr-qcPRD(2024)·6 citations
05
Investigating the weak charge of $^{48}$ Ca using a dispersive optical model
N. L. Calleya · M. C. Atkinson · W. H. Dickhoff
A new nonlocal dispersive-optical-model analysis has been carried out for neutrons and protons in $^{48}$ Ca that reproduces the weak-form-factor measurement of CREX. In addition to elastic-scattering angular distributions, total and reaction cross sections, single-particle energies, the neutron and proton numbers, and the charge distribution, the CREX-measured weak form factor has been fit to extract the neutron and proton self-energies both above and below the Fermi energy. The resulting single-particle propagators yield a weak form factor of $F_{W} = 0.125 \pm 0.05$ and a neutron skin of $R_{skin} = 0.152 \pm 0.05$ fm, in good agreement with CREX. The rearrangement of the neutron distribution to accommodate such a thin neutron skin results in the high-momentum content of the neutrons exceeding that of the protons, in contrast to what is expected from high-energy two-nucleon knockout measurements by the CLAS collaboration and ab initio asymmetric matter calculations. The present analysis also emphasizes the importance of neutron experimental data in constraining weak charge observables necessary for a precise description of neutron densities. Notably, the neutron reaction cross section and further parity-violating experiments weak form factor measurements are essential to generate a unique way to determine the $^{48}$ Ca neutron distribution in this framework.
nucl-thPLB(2025)·3 citations
06
State-of-the-art of Strangeness in Quark Matter Theory 2024
Jacquelyn Noronha-Hostler🇺🇸
I discuss the theoretical developments in related to Strangeness in Quark Matter (SQM) leading up to the SQM2024 conference. These advances include mapping out the Quantum Chromodynamics phase diagram; puzzles that exist in hadron physics from light to heavy particles; and advanced in relativistic hydrodynamics with the inclusion of spin and magnetic fields.
nucl-thastro-ph.HEhep-ph0 citations
07
Femtoscopic study of the $Ω α$ interaction in heavy-ion collisions
Faisal Etminan🇮🇷
The two-particle momentum correlation between the Omega-baryon ( $Ω$ ) and the $^{4} H e (α)$ in high-energy heavy ion collisions is explored. Such correlations as an alternative source of information can help us further understand the interaction between $Ω$ and nucleons (N). $Ω α$ potentials in the single-folding potential approach are constructed by employing two different available $Ω N$ interactions in $^{5} S_{2}$ channel, i.e, one is based on the (2 + 1)-flavor lattice QCD simulations near the physical point by the HAL QCD collaboration, and another is based on the meson exchanges with effective Lagrangian, where in the latter case coupled channels effect is considered. It is found that the correlation functions at small size source depends on the used potential model. This implicitly means that at high density nuclear medium, $Ω α$ momentum correlation could drive the feature of $Ω N$ interactions. Moreover, by extracting the scattering length and the effective range from obtained $Ω α$ potentials, the correlation functions are calculated within the Lednicky-Lyuboshits (LL) formalism. It is shown that since the $Ω α$ has large interaction range, the LL formula leads to different results at small source size.
nucl-thhep-phPRC(2025)·8 citations
08
On elliptic flow and the blast-wave model
Boris Tomasik🇨🇿
Extensions of the blast-wave model for the description of non-central collisions are reviewed and the physics behind them is explained and illustrated. It is shown how the second-order anisotropy in expansion velocity together with the anisotropy in the shape or the density profile of the fireball determine the elliptic flow of the produced hadrons. Ambiguities and limitations of the models are discussed and different models are compared among themselves and with example data. It is concluded that model results should always be compared to $v_{2} (p_{t})$ from several identified species in order to receive meaningful results about the freeze-out stage of the fireball and that even such a comparison may not be conclusive as the models may not be able to reproduce all relevant data.
nucl-thInt.J.Mod.Phys.A(2025)·4 citations
09
Anisotropic hydrodynamics with boost-non-invariant expansion
Shile Chen🇨🇳 · Shuzhe Shi🇨🇳
We establish the anisotropic hydrodynamics (aHydro) equations based on a boost-non-invariant longitudinally expanding system. Good consistency is found in the comparison between the aHydro results with those from the Boltzmann equation under relaxation time approximation. We also obtain corresponding attractor solution and observe the time delay of convergence when increasing the absolute value of the rapidity. We finally show that the rapidity dependence is solved by introducing the redefined attractor variables to compensate the time delay effect.
nucl-thhep-phPRD(2025)·5 citations
10
SMASH as an event generator for heavy-ion collisions
A. Sciarra🇩🇪 · H. Elfner🇩🇪
In this article we present an overview of the SMASH hadronic transport approach that is applied for non-equilibrium dynamics of hadrons in \heavyion\ collisions. We will give an overview about the ingredients of the approach and the applications for the dynamical description of \heavyion\ collisions and for calculations of fundamental properties of the hadron gas. The main emphasis of the article will be the infrastructure for sustainable software development that we have developed over the last 10 years including extensive unit tests and continuous integration. We will also provide one section about the performance of the code and how it can be analyzed and improved in the future.
nucl-thnucl-exFront.in Phys.(2024)·7 citations
11
Nuclear shape / phase transitions in the N = 40, 60, 90 regions
Dimitrios Petrellis (1) · Adam Prášek (2) · Petr Alexa (2) · Dennis Bonatsos (3) · Gabriela Thiamová (4) · Petr Veselý (1) ((1) Nuclear Physics Institute of the Czech Academy of Sciences, (2) Department of Physics, VŠB - Technical University Ostrava, (3) Institute of Nuclear and Particle Physics, National Centre for Scientific Research "Demokritos", (4) Universite Grenoble 1, CNRS, LPSC, Institut Polytechnique de Grenoble, IN2P3)
We investigate the isotopes of Se, Zr, Mo and Nd in the regions with N = 40, 60 and 90, where a first-order shape / phase transition, from spherical to deformed, can be observed. The signs of phase transitional behavior become evident by examining structure indicators, such as certain energy ratios and B(E2) transition rates and, in particular, how they evolve with neutron number. Microscopic mean-field calculations using the Skyrme-Hartree-Fock + Bardeen-Cooper-Schrieffer framework also reveal structural changes when considering the evolution of the resulting potential energy curves as functions of deformation. Finally, macroscopic calculations, using the Algebraic Collective Model, specifically for $^{74}$ Se, $^{102}$ Mo and $^{150}$ Nd, after fitting its parameters to experimental spectra, result in potentials that resemble some of the potentials proposed in the framework of the Bohr Hamiltonian to describe shape transitions in nuclei.
nucl-thEPJ Web Conf.(2024)·0 citations
12
Big Bang: a theory or fact
D. N. Basu
The discovery and confirmation that some nuclides were formed soon after the Big Bang is one of the strongest arguments in favour of the Hot Big Bang theory. The process of combining protons and neutrons in a hot, expanding universe is known as Big Bang nucleosynthesis (or, occasionally, primordial nucleosynthesis). The only experiment that is currently constructed to be concurrently sensitive to all four known fundamental forces - gravitational, electromagnetic, strong and weak forces - is big bang nucleosynthesis, which offers our earliest test of cosmology. Combined, our theoretical comprehension of Big Bang nucleosynthesis and the measurement of primordial abundances constitute one of the most robust foundations for the conventional cosmological model. This deliberation provides modern calculations of Big Bang nucleosynthesis, help readers gain an intuitive knowledge of the process and give an overview of the most recent state-of-the-art measurements. Our trust in the current basic picture of cosmology is reinforced by the overall amazing agreement between Big Bang nucleosynthesis and many cosmological probes.
nucl-thphysics.pop-ph0 citations
13
Quarks to Cosmos: Particles and Plasma in Cosmological evolution
Johann Rafelski🇺🇸 · Jeremiah Birrell🇺🇸 · Christopher Grayson🇺🇸 · Andrew Steinmetz🇺🇸 · Cheng Tao Yang🇺🇸
We describe in the context of the particle physics (PP) standard model (SM) `PP-SM' the understanding of the primordial properties and composition of the Universe in the temperature range $130 \GeV > T > 20 \keV$ . The Universe evolution is described using FLRW cosmology. We present a global view on particle content across time and describe the different evolution eras using deceleration parameter $q$ . We follow the arrow of time in the expanding and cooling Universe: After the PP-SM heavies $(t, h, W, Z)$ diminish in abundance below $T ≃ 50 \GeV$ , the PP-SM plasma in the Universe is governed by the strongly interacting Quark-Gluon content. Once the temperature drops below $T ≃ 150 \MeV$ , quarks and gluons hadronize into strongly interacting matter particles. Rapid disappearance of baryonic antimatter completes at $T_{B} = 38.2 \MeV$ . We study the ensuing disappearance of strangeness and mesons in general. We show that the different eras defined by particle populations are barely separated from each other with abundance of muons fading out just prior to $T = O (2.5) \MeV$ , the era of emergence of the free-streaming neutrinos. We discuss the two relevant fundamental constants controlling the decoupling of neutrinos. We subsequently follow the primordial Universe as it passes through the hot dense electron-positron plasma epoch. The high density of positron antimatter disappears near $T = 20.3 \keV$ : Nuclear reactions occur in the presence of a highly mobile and relatively strongly interacting electron-positron plasma phase. We apply plasma theory methods to describe the strong screening effects between heavy dust particle (nucleons). We analyze the paramagnetic characteristics of the electron-positron plasma when exposed to an external primordial magnetic field.
↳ hep-phastro-ph.COnucl-thphysics.plasm-phEur.Phys.J.ST(2025)·8 citations
14
Revisiting Single Inclusive Jet Production: Timelike Factorization and Reciprocity
Kyle Lee🇺🇸 · Ian Moult🇺🇸 · Xiaoyuan Zhang🇺🇸
Factorization theorems for single inclusive jet production play a crucial role in the study of jets and their substructure. In the case of small radius jets, the dynamics of the jet clustering can be factorized from both the hard production dynamics, and the dynamics of the low scale jet substructure measurement, and is described by a matching coefficient that can be computed in perturbative Quantum Chromodynamics (QCD). A proposed factorization formula describing this process has been previously presented in the literature, and is referred to as the semi-inclusive, or fragmenting jets formalism. By performing an explicit two-loop calculation, we show the inconsistency of this factorization formula, in agreement with another recent result in the literature. Building on recent progress in the factorization of single logarithmic observables, and the understanding of reciprocity, we then derive a new all-order factorization theorem for inclusive jet production. Our factorization involves a non-trivial convolution structure, that maintains the universality of the hard function from inclusive fragmentation. We perform an explicit two-loop calculation of the jet function in both $N = 4$ super Yang-Mills (SYM), and for all color channels in QCD, finding exact agreement with the structure derived from our renormalization group equations. In addition, we derive several new results, including an extension of our factorization formula to jet substructure observables, a jet algorithm definition of a generating function for the energy correlators, and new results for exclusive jet functions. Our results are a key ingredient for achieving precision jet substructure at colliders.
↳ hep-phhep-exnucl-thJHEP(2025)·34 citations
15
Quarkonium production in pp and heavy-ion collisions
Taesoo Song🇩🇪 · Joerg Aichelin🇫🇷 · Jiaxing Zhao🇩🇪 · Pol B. Gossiaux🇫🇷 · Elena Bratkovskaya🇩🇪
We describe bottomonium production not only in pp collisions but also in heavy-ion collisions by using the Remler's formalism where quarkonium density operator is applied to all possible combination of heavy quark and heavy antiquark pairs. In pp collisions heavy (anti)quark momentum is provided by the PYTHIA event generator after rescaling $p_{T}$ and rapidity to imitate the FONLL calculations. Then spatial separation between heavy quark and heavy antiquark is introduced based on the uncertainty principle. In heavy-ion collisions quarkonium wavefunction changes with temperature assuming heavy quark potential equals the free energy of heavy quark and heavy antiquark system in heat bath. The density operator is updated whenever heavy quark or heavy antiquark scatters in QGP produced in heavy-ion collisions. Our results are consistent with the experimental data from ALICE and CMS Collaborations assuming that the interaction rate of heavy (anti)quark in quarkonium is suppressed to 10 \% that of unbound heavy (anti)quark. We also find that off-diagonal recombination of bottomonium barely happens even in Pb+Pb collisions at $s = 5.02$ TeV.
↳ hep-phnucl-thEPJ Web Conf.(2025)·2 citations
16
Transport properties of the strongly interacting quark-gluon plasma
Ilia Grishmanovskii🇩🇪 · Taesoo Song🇩🇪 · Olga Soloveva🇩🇪 · Carsten Greiner🇩🇪 · Elena Bratkovskaya🇩🇪
We investigate the transport properties of the strongly interacting quark-gluon plasma (sQGP) by comparing the role of elastic and inelastic (radiative) processes in the sQGP medium within the effective dynamical quasi-particle model (DQPM), constructed for the description of non-perturbative quantum chromodynamic (QCD) phenomena of the sQGP in line with the lattice QCD (lQCD) equation of state. First, we present the results for the energy and temperature dependencies of the total radiative cross sections and compare them to the corresponding elastic cross sections. Second, we perform a calculation of the interaction rate and relaxation time of radiative versus elastic scatterings. Finally, we obtain the jet transport coefficient $q^$ and investigate its dependence on the choice of the strong coupling in thermal, jet parton and radiative vertices.
↳ hep-phnucl-thPoS(2025)·0 citations
17
On the origin of the peak of the sound velocity for isospin imbalanced strongly interacting matter
Alejandro Ayala🇲🇽 · Bruno S. Lopes🇧🇷 · Ricardo L. S. Farias🇧🇷 · Luis C. Parra🇲🇽
We study the properties of a system composed of strongly interacting matter with an isospin imbalance, using as an effective description of QCD the two-flavor Linear Sigma Model with quarks. From the one-loop effective potential, including the two light quarks, pions and sigma contributions, and enforcing the restrictions imposed by chiral symmetry, we show that the development of an isospin condensate comes together with the emergence of a Goldstone mode that provides a constraint for the chiral and isospin condensates as a result of a non-trivial mixing between the charged pions and the sigma. We compute the thermodynamical quantities of interest and in particular the sound velocity squared, showing that it presents a maximum for an isospin chemical potential similar to the one reported by lattice QCD results and also with a similar height. Therefore, we attribute the origin of the peak of the sound velocity to the proper treatment of the Goldstone mode and to the non-trivial mixing of the charged pions and sigma in the isospin condensed phase.
↳ hep-phhep-latnucl-exnucl-thPLB(2025)·17 citations
18
Hypercontractivity and factorial moment scaling in the symmetry broken phase
Athanasios Brofas🇬🇷 · Manolis Zampetakis🇺🇸 · Fotios Diakonos🇬🇷
The search for remnants of the QCD chiral critical point is a central objective of current and future high-energy ion collision experiments. Previous studies suggest that a scaling law relating higher-order factorial moments of hadron multiplicity fluctuations to the second factorial moment could serve as a tool for detecting the QCD critical point. However, we demonstrate that this scaling law is not unique to critical phenomena. Instead, it emerges as a general property of distributions by extending the concept of hypercontractivity, originally applied to ordinary moments, to factorial moments. We present examples of distribution classes that exhibit the same higher-order factorial moment scaling as multiplicity fluctuations in the symmetry-broken phase. This insight allows us to explain the recent intermittency analysis results from the STAR experiment at RHIC (arXiv:2301.11062), where no indication of criticality was observed.
↳ hep-phhep-exhep-thnucl-ex+1PLB(2025)·3 citations
19
A Deep Learning Based Estimator for Light Flavour Elliptic Flow in Heavy Ion Collisions at LHC Energies
Gergely Gábor Barnaföldi🇭🇺 · Neelkamal Mallick🇭🇺 · Suraj Prasad🇭🇺 · Raghunath Sahoo🇮🇳 · Aditya Nath Mishra🇮🇳
We developed a deep learning feed-forward network for estimating elliptic flow ( $v_{2}$ ) coefficients in heavy-ion collisions from RHIC to LHC energies. The success of our model is mainly the estimation of $v_{2}$ from final state particle kinematic information and learning the centrality and the transverse momentum ( $p_{T}$ ) dependence of $v_{2}$ in wide $p_{T}$ regime. The deep learning model is trained with AMPT-generated Pb-Pb collisions at $s_{NN} = 5.02$ TeV minimum bias events. We present $v_{2}$ estimates for $π^{\pm}$ , $K^{\pm}$ , and $p + p ˉ$ in heavy-ion collisions at various LHC energies. These results are compared with the available experimental data wherever possible.
↳ hep-phnucl-thEPJ Web Conf.(2025)·0 citations
20
Phase-Space methods for neutrino oscillations: extension to multi-beams
Denis Lacroix🇫🇷 · Angel Bauge🇫🇷 · Bulent Yilmaz🇹🇷 · Mariane Mangin-Brinet🇫🇷 · Alessandro Roggero🇮🇹 · A. Baha Balantekin🇺🇸
The Phase-Space approach (PSA), which was originally introduced in [Lacroix et al., Phys. Rev. D 106, 123006 (2022)] to describe neutrino flavor oscillations for interacting neutrinos emitted from stellar objects is extended to describe arbitrary numbers of neutrino beams. The PSA is based on mapping the quantum fluctuations into a statistical treatment by sampling initial conditions followed by independent mean-field evolution. A new method is proposed to perform this sampling that allows treating an arbitrary number of neutrinos in each neutrino beam. We validate the technique successfully and confirm its predictive power on several examples where a reference exact calculation is possible. We show that it can describe many-body effects, such as entanglement and dissipation induced by the interaction between neutrinos. Due to the complexity of the problem, exact solutions can only be calculated for rather limited cases, with a limited number of beams and/or neutrinos in each beam. The PSA approach considerably reduces the numerical cost and provides an efficient technique to accurately simulate arbitrary numbers of beams. Examples of PSA results are given here, including up to 200 beams with time-independent or time-dependent Hamiltonian. We anticipate that this approach will be useful to bridge exact microscopic techniques with more traditional transport theories used in neutrino oscillations. It will also provide important reference calculations for future quantum computer applications where other techniques are not applicable to classical computers.
↳ hep-phhep-thnucl-thquant-phPRD(2024)·15 citations
21
Stars and quark stars in bumblebee gravity
Juliano C. S. Neves🇧🇷 · Fernando G. Gardim🇧🇷
In this work, the interior spacetime of stars is built in a Lorentz symmetry breaking model called bumblebee gravity. Firstly, we calculated the modified Tolman-Oppenheimer-Volkoff equation in this context of modified gravity. Then we show that the bumblebee field, responsible for the symmetry breaking, increases the star mass-radius relation when it assumes its vacuum expectation value. When compared to the general relativity mass-radius relation, a Lorentz symmetry breaking context, like the bumblebee gravity, could provide more massive stars, surpassing the $2.5 M_{⊙}$ limit as the interior of the star is described by quark matter with the MIT bag model. Also, we investigate the stability of the solution with the MIT bag equation of state in this context of modified gravity.
↳ gr-qchep-thnucl-thAnnals Phys.(2025)·19 citations
22
Breakdown of collinear factorisation in the photoproduction of a $π^{0} γ$ pair with large invariant mass
Saad Nabeebaccus🇫🇷 · Jakob Schoenleber🇩🇪 · Lech Szymanowski🇵🇱 · Samuel Wallon🇫🇷
We identify a $2 \to 3$ exclusive process, where collinear factorisation is broken, namely the exclusive photoproduction of a $π^{0} γ$ pair with large invariant mass. This occurs because the process suffers from gluon exchanges trapped in the Glauber region. Using an explicit example, we show that the Glauber gluon, which is exchanged between a collinear spectator parton from the nucleon sector and a soft spectator parton from the outgoing pion, has both of its lightcone plus and minus components pinched. Therefore, it cannot be deformed to collinear/soft regions, as is often the case for processes that do factorise. We further confirm the leading power behaviour of the identified Glauber region, highlighting that this is the case although it relies on extracting a soft parton from the outgoing pion. We stress that the Glauber pinch for this process is of the leading power, due to the possibility of having two-gluon exchanges between the collinear nucleon sector and hard partonic scattering sub-process. In fact, the Glauber gluon that we identify is one of these two active gluons, and therefore, its effects are observed already at leading order. A direct consequence of our work is that collinear factorisation breaks in the same way for other $2 \to 3$ exclusive processes, where two-gluon exchanges in the $t$ -channel are possible, like in the exclusive production of a photon pair from $π^{0} N$ collisions. However, we highlight that in cases where such two-gluon exchanges do not exist, like in the exclusive $π^{\pm} γ$ photoproduction, the Glauber exchanges that we discuss here do not occur, and hence they do not suffer from factorisation breaking effects.
↳ hep-phnucl-thPoS(2025)·1 citation
23
Complete 1-loop study of exclusive $J / ψ$ and $Υ$ photoproduction with full GPD evolution
Chris Flett🇫🇷 · Jean-Philippe Lansberg🇫🇷 · Saad Nabeebaccus🇫🇷 · Maxim Nefedov🇫🇷 · Pawel Sznajder🇵🇱 · Jakub Wagner🇵🇱
We discuss the exclusive photoproduction of a heavy vector quarkonium, namely $J / ψ$ and $Υ$ at 1-loop in $α_{s}$ . In collinear factorisation (CF), the amplitude for such a process is obtained by the convolution of a hard partonic sub-amplitude, with a universal generalised parton distribution (GPD). For the first time, we perform a complete calculation at 1-loop including full leading-log (LL) GPD evolution. We first demonstrate the huge instability of the cross section at high energies when the factorisation scale $μ_{F}$ is varied. This instability has been reported previously in the literature, and occurs due to the large logarithms generated by the huge difference between the hard scale of the process, which is the mass of the heavy quarkonium here, and the centre-of-mass energy of the process. This problem was also reported in inclusive heavy vector quarkonium photoproduction. We show that this issue can be resolved by resumming these large logarithms using high-energy factorisation (HEF), by performing a matching with the result in CF using the doubly logarithmic approximation (DLA) in order to be consistent with the fixed order evolution of GPDs. Finally, we show that the cross sections obtained from such a matching, besides being free from the previously mentioned factorisation scale variation instabilities, are consistent with the H1 data for $J / ψ$ production and with the ZEUS data for $Υ$ production.
↳ hep-phhep-exnucl-exnucl-thPoS(2025)·0 citations
24
Sokolov--Ternov effect in rotating systems
Jonathan D. Kroth🇺🇸 · Kirill Tuchin🇺🇸
We study electromagnetic radiation by electrically charged fermions embedded in a rotating medium in an external magnetic field. We compute the dependence of the radiation intensity on the angular velocity $Ω$ of the rotating medium for fermion polarizations along and opposite the magnetic field direction in intense subcritical fields. The polarization dependence of the photon radiation results in the Sokolov--Ternov effect -- the radiative polarization of fermions. We study the dependence of the degree of polarziation on $Ω$ . We found that rotation significantly changes the degree of polarization. We show that the rotating quark-gluon plasma acquires a finite magnetic moment that exhibits complex dependence on $Ω$ .
↳ hep-phnucl-thPRD(2025)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE