Nuclear Theory·nucl-th

Tuesday·July 18, 2023

19 papers—4 primary·15 cross-listed

01
Prescaling relaxation to nonthermal attractors
Michal P. Heller🇧🇪 · Aleksas Mazeliauskas🇩🇪 · Thimo Preis🇩🇪
We study how isotropic and homogeneous far-from-equilibrium quantum systems relax to nonthermal attractors, which are of interest for cold atoms and nuclear collisions. We demonstrate that a first-order ordinary differential equation governs the self-similar approach to nonthermal attractors, i.e., the prescaling. We also show that certain natural scaling-breaking terms induce logarithmically slow corrections that prevent the scaling exponents from reaching the constant values during the system's lifetime. We propose that, analogously to hydrodynamic attractors, the appropriate mathematical structure to describe such dynamics is the transseries. We verify our analytic predictions with state-of-the-art 2PI simulations of the large-N vector model and QCD kinetic theory.
hep-thcond-mat.quant-gashep-phnucl-thPRL(2024)·23 citations
02
Energy Loss in Small Collision Systems
Coleridge Faraday🇿🇦 · W. A. Horowitz🇿🇦
We present leading hadron suppression predictions in $P b + P b$ and $p + P b$ collisions from a convolved radiative and collisional energy loss model in which partons propagate through a realistic background, and in which the radiative energy loss receives a short pathlength correction. We find that the short pathlength correction is small for $D$ meson $R_{AA} (p_{T})$ in both $P b + P b$ and $p + P b$ collisions. However the short pathlength correction leads to a surprisingly large reduction in suppression for $π$ mesons in $p + P b$ and even $P b + P b$ collisions, providing a qualitative explanation for the rapid rise in $π$ meson $R_{AA} (p_{T})$ at the LHC. We find that the size of the short pathlength correction to $R_{AA} (p_{T})$ is acutely sensitive to the chosen distribution of scattering centers in the plasma. Furthermore we find that conventional elastic energy loss models, which apply the central limit theorem to the number of scatterings, dramatically overpredict suppression in $p + A$ collisions, calling for short pathlength corrections to elastic energy loss.
nucl-thhep-phPoS(2024)·3 citations
03
Illuminating early-stage dynamics of heavy-ion collisions through photons at RHIC BES energies
Chun Shen🇺🇸 · Abel Noble🇺🇸 · Jean-François Paquet🇺🇸 · Björn Schenke🇺🇸 · Charles Gale🇨🇦
Heavy-ion collisions at $s_{NN} \sim 10$ GeV probe the QCD phase diagram at large baryon densities. Because the longitudinal Lorentz contraction is small at these collision energies, understanding the dynamics during the early phase of the collision is essential for the subsequent modeling of the system evolution and for constraining the QGP transport properties at finite baryon densities. Direct photons provide undistorted information on early-stage dynamics. We model relativistic heavy-ion collisions at RHIC Beam Energy Scan energies with a hybrid dynamical approach consisting of a 3D-Glauber initial state followed by viscous hydrodynamics and hadronic transport (MUSIC + UrQMD). The implemented thermal photon emission takes into account the enhancement from finite baryon chemical potentials. We show that direct photon spectra and their anisotropic flow coefficients have a strong sensitivity to the early stage of heavy-ion collisions. Thus, they provide constraints on QGP dynamics complementary to those obtained from hadronic observables.
nucl-thhep-phnucl-exPoS(2024)·8 citations
04
Canonical Ensemble vs. Grand Canonical Ensemble in the Description of Multicomponent Bosonic Systems
D. Anchishkin · V. Gnatovskyy · D. Zhuravel · V. Karpenko · I. Mishustin · H. Stoecker
The thermodynamics of a system of interacting bosonic particles and antiparticles in the presence of the Bose-Einstein condensate is studied in the framework of the Skyrme-like mean-field model. It is assumed that the total charge density (isospin density) is conserved at all temperatures. Two cases are explicitly considered: zero and nonzero isospin charge of the system. A comparative analysis is carried out using Canonical Ensemble and Grand Canonical Ensemble. It is shown that the Grand Canonical Ensemble is not suitable for describing bosonic systems of particles and antiparticles in the presence of condensate.
nucl-thhep-phquant-phUkr.J.Phys.(2024)·1 citation
05
Emergent symmetries of relativistic fluid dynamics from local ergodicity
Giorgio Torrieri🇧🇷
We show that volume-preserving diffomorphisms and the chemical shift symmetry defining relativistic lagrangian ideal fluid dynamics can be derived as an emerging symmetry when ergodicity is assumed to apply locally in a way that is invariant under smooth spacetime foliations. This can be used as a way to derive the ideal hydrodynamic limit in a strongly coupled but strongly fluctuating medium. We comment on the connection with thermalization in small systems, the Eigenstate thermalization hypothesis and deviations from the ideal limit.
↳ hep-thgr-qchep-phnucl-thPRD(2024)·15 citations
06
PRyMordial: The First Three Minutes, Within and Beyond the Standard Model
Anne-Katherine Burns🇺🇸 · Tim M.P. Tait🇺🇸 · Mauro Valli🇺🇸
In this work we present PRyMordial: A package dedicated to efficient computations of observables in the Early Universe with the focus on the cosmological era of Big Bang Nucleosynthesis (BBN). The code offers fast and precise evaluation of BBN light-element abundances together with the effective number of relativistic degrees of freedom, including non-instantaneous decoupling effects. PRyMordial is suitable for state-of-the-art analyses in the Standard Model as well as for general investigations into New Physics active during BBN. After reviewing the physics implemented in PRyMordial, we provide a short guide on how to use the code for applications in the Standard Model and beyond. The package is written in Python, but more advanced users can optionally take advantage of the open-source community for Julia. PRyMordial is publicly available on GitHub.
↳ hep-phastro-ph.COnucl-thEPJC(2024)·85 citations
07
Level Structures of $^{56, 58}$ Ca Cast Doubt on a doubly magic $^{60}$ Ca
S. Chen🇨🇳 · F. Browne🇯🇵 · P. Doornenbal🇯🇵 · J. Lee🇨🇳 · A. Obertelli🇩🇪 · Y. Tsunoda🇯🇵 · T. Otsuka🇯🇵 · Y. Chazono🇯🇵 · G. Hagen🇺🇸 · J.D. Holt🇨🇦 · G.R. Jansen🇺🇸 · K. Ogata🇯🇵 and 71 other authors
Gamma decays were observed in $^{56}$ Ca and $^{58}$ Ca following quasi-free one-proton knockout reactions from $^{57, 59}$ Sc beams at $\approx 200$ MeV/nucleon. For $^{56}$ Ca, a $γ$ ray transition was measured to be 1456(12) keV, while for $^{58}$ Ca an indication for a transition was observed at 1115(34) keV. Both transitions were tentatively assigned as the $2_{1}^{+} \to 0_{g s}^{+}$ decays, and were compared to results from ab initio and conventional shell-model approaches. A shell-model calculation in a wide model space with a marginally modified effective nucleon-nucleon interaction depicts excellent agreement with experiment for $2_{1}^{+}$ level energies, two-neutron separation energies, and reaction cross sections, corroborating the formation of a new nuclear shell above the $N$ = 34 shell. Its constituents, the $0 f_{5/2}$ and $0 g_{9/2}$ orbitals, are almost degenerate. This degeneracy precludes the possibility for a doubly magic $^{60}$ Ca and potentially drives the dripline of Ca isotopes to $^{70}$ Ca or even beyond.
↳ nucl-exnucl-thPLB(2023)·21 citations
08
Nuclear Level Density and $γ$ -ray Strength Function of $^{67} Ni$ and the impact on the i-process
V. W. Ingeberg🇳🇴 · S. Siem🇳🇴 · M. Wiedeking🇺🇸 · A. Choplin🇧🇪 · S. Goriely🇧🇪 · L. Siess🇧🇪 · K. J. Abrahams🇿🇦 · K. Arnswald🇩🇪 · F. Bello Garrote🇳🇴 · D. L. Bleuel🇺🇸 · J. Cederkäll · T. L. Christoffersen🇳🇴 and 20 other authors
Proton- $γ$ coincidences from $(d, p)$ reactions between a $^{66} Ni$ beam and a deuterated polyethylene target have been analyzed with the inverse-Oslo method to find the nuclear level density (NLD) and $γ$ -ray strength function ( $γ$ SF) of $^{67} Ni$ . The $^{66} Ni (n, γ)$ capture cross section has been calculated using the Hauser-Feshbach model in TALYS using the measured NLD and $γ$ SF as constraints. The results confirm that the $^{66} Ni (n, γ)$ reaction acts as a bottleneck when relying on one-zone nucleosynthesis calculations. However, the impact of this reaction is strongly dampened in multi-zone models of low-metallicity AGB stars experiencing i-process nucleosynthesis.
↳ nucl-exastro-ph.SRnucl-thPRC(2025)·9 citations
09
Nuclear Physics in the Era of Quantum Computing and Quantum Machine Learning
J.E. García-Ramos🇪🇸 · A. Sáiz🇪🇸 · J.M. Arias🇪🇸 · L. Lamata🇪🇸 · P. Pérez-Fernández🇪🇸
In this paper, the application of quantum simulations and quantum machine learning to solve low-energy nuclear physics problems is explored. The use of quantum computing to deal with nuclear physics problems is, in general, in its infancy and, in particular, the use of quantum machine learning in the realm of nuclear physics at low energy is almost nonexistent. We present here three specific examples where the use of quantum computing and quantum machine learning provides, or could provide in the future, a possible computational advantage: i) the determination of the phase/shape in schematic nuclear models, ii) the calculation of the ground state energy of a nuclear shell model-type Hamiltonian and iii) the identification of particles or the determination of trajectories in nuclear physics experiments.
↳ quant-phnucl-exnucl-thAdv.Quantum Technol.(2025)·19 citations
10
Photon and dilepton emission anisotropy for a magnetized quark-gluon plasma
Xinyang Wang🇨🇳 · Igor A. Shovkovy🇺🇸
We study the higher-order anisotropy coefficients $v_{4}$ and $v_{6}$ in the photon and dilepton emission from a hot magnetized quark-gluon plasma. Together with the earlier predictions for $v_{2}$ , these results show a distinctive pattern of the anisotropy coefficients in several kinematic regimes. In the case of photon emission, nonzero coefficients $v_{n}$ (with even $n$ ) have opposite signs at small and large values of the transverse momentum (i.e., $k_{T} ≲ ∣ e B ∣$ and $k_{T} ≳ ∣ e B ∣$ , respectively). Additionally, the $v_{n}$ signs alternate with increasing $n$ , and their approximate values decrease as $1/ n^{2}$ in magnitude. The anisotropy of dilepton emission is well pronounced only at large transverse momenta and small invariant masses (i.e., when $k_{T} ≳ ∣ e B ∣$ and $M ≲ ∣ e B ∣$ ). The corresponding $v_{4}$ and $v_{6}$ coefficients are of the same magnitude and show a similar alternating sign pattern with increasing $n$ as in the photon emission.
↳ hep-phnucl-thPRD(2024)·12 citations
11
Studying QGP transport properties in a concurrent minijet+hydro framework
Charles Gale🇨🇦 · Sangyong Jeon🇨🇦 · Daniel Pablos🇪🇸 · Mayank Singh🇺🇸
Minijets are ubiquitous in heavy-ion collision experiments. However, they are often excluded from the hydrodynamic simulations of QGP as they do not thermalize at short time scales and are not treated as part of the collective medium. Using a concurrent jet+hydro framework, we show that the minijets could account for a significant portion of particle multiplicity. Therefore, the energy deposition from minijet-medium interactions can substantially modify the QGP transport properties inferred from model-to-data comparisons.
↳ hep-phnucl-thPoS(2024)·0 citations
12
Comparative multi-probe study of jet energy-loss in QGP
Rouzbeh Modarresi Yazdi🇨🇦 · Shuzhe Shi🇺🇸 · Charles Gale🇨🇦 · Sangyong Jeon🇨🇦
Jet-energy loss is an important sign of the creation of Quark-Gluon Plasma in heavy-ion collisions. High transverse momentum ( $p_{T}$ ) partons are produced at the moment of initial hard scattering and are modified as a result of their propagation through the created medium. We study two models of low-virtuality radiative energy loss: CUJET and MARTINI. This is done using the JETSCAPE framework, which allows for an objective comparison. CUJET is integrated into the JETSCAPE workflow, and full jet simulations, including substructure observables, are computed for the first time using leading-order DGLV rates. Strongly-interacting probes (charged hadrons, jets, jet fragmentation functions and jet shape ratio) are considered along jet-medium photons for the first time in a dynamic QGP. We find that these photons make a significant contribution in the phenomenologically interesting intermediate $p_{T}$ domain of $4$ - $12$ GeV.
↳ hep-phnucl-thPoS(2024)·1 citation
13
Understanding the total width of the $3_{1}^{-}$ state in $^{12} C$
K. C. W. Li · R. Neveling · P. Adsley · H. Fujita · P. Papka · F. D. Smit · J. W. Brümmer · L. M. Donaldson · M. N. Harakeh · Tz. Kokalova · E. Nikolskii · W. Paulsen and 3 other authors
Recent measurements indicate that the previously established upper limit for the $γ$ -decay branch of the $3_{1}^{-}$ resonance in $^{12} C$ at $E_{x} = 9.641 (5)$ MeV may be incorrect. As a result, the $3_{1}^{-}$ resonance has been suggested as a significant resonance for mediating the triple- $α$ reaction at high temperatures above 2 GK. Accurate estimations of the $3_{1}^{-}$ contribution to the triple- $α$ reaction rate require accurate knowledge of not only the radiative width, but also the total width. In anticipation of future measurements to more accurately determine the $γ$ -decay branch of the $3_{1}^{-}$ resonance, the objective of this work is to accurately determine the total width of the $3_{1}^{-}$ resonance. An evaluation was performed on all previous results considered in the current ENSDF average of 46(3) keV for the physical total width (FWHM) of the $3_{1}^{-}$ resonance in $^{12} C$ . Significant unaccounted-for uncertainties and a misstated result were discovered in these previous results, leading to an invalid ENSDF average. In this work, the new global \textbf{R}-matrix analysis performed on direct-reaction data yields a formal total width of $Γ (E_{r}) = 46 (2)$ keV and an observed total width of $Γ_{obs} (E_{r}) = 38 (2)$ keV for the $3_{1}^{-}$ resonance. An observed total width of $Γ_{obs} (E_{r}) = 38 (2)$ keV is recommended for the $3_{1}^{-}$ resonance in $^{12} C$ . This observed total width should be employed for future evaluations of the observed total radiative width for the $3_{1}^{-}$ resonance and its contribution to the high-temperature triple- $α$ reaction rate.
↳ nucl-exnucl-thPRC(2024)·3 citations
14
Heavy quark $κ$ and jet $q^$ transport coefficients in the Glasma early stage of heavy-ion collisions
Dana Avramescu🇫🇮 · Virgil Băran🇷🇴 · Vincenzo Greco🇮🇹 · Andreas Ipp🇦🇹 · David. I. Müller🇦🇹 · Marco Ruggieri🇮🇹
We study the impact of the Glasma fields, used to describe the very early stage of heavy-ion collisions, on the transport of hard probes, namely heavy quarks and jets. We perform numerical simulations of the strong classical fields using techniques from real-time lattice gauge theory. The resulting fields are used as background for the classical transport of ensembles of particles, described by Wong's equations. For this purpose, we develop a numerical solver for the transport of the probes, based on colored particle-in-cell methods. We focus on the dynamics of heavy quarks and jets in the classical colored fields. To quantify the effect of the Glasma, we extract the momentum broadening of hard probes and evaluate the anisotropy transfer from the Glasma to the probes. Lastly, we evaluate the heavy quark $κ$ and jet $q^$ transport coefficients in the Glasma, which turn out to be large and exhibit a peak, irrespective of the particle initialization.
↳ hep-phhep-latnucl-thPoS(2024)·4 citations
15
Effects of multi-scale jet-medium interactions on jet substructures
JETSCAPE Collaboration: Y. Tachibana · A. Angerami · R. Arora · S. A. Bass · S. Cao · Y. Chen · T. Dai · L. Du · R. Ehlers · H. Elfner · W. Fan · R. J. Fries and 47 other authors
We utilize event-by-event Monte Carlo simulations within the JETSCAPE framework to examine scale-dependent jet-medium interactions in heavy-ion collisions. The reduction in jet-medium interaction during the early high-virtuality stage, where the medium is resolved at a short distance scale, is emphasized as a key element in explaining multiple jet observables, particularly substructures, simultaneously. By employing the MATTER+LBT setup, which incorporates this explicit reduction of medium effects at high virtuality, we investigate jet substructure observables, such as Soft Drop groomed observables. When contrasted with existing data, our findings spotlight the significant influence of the reduction at the early high-virtuality stages. Furthermore, we study the substructure of gamma-tagged jets, providing predictive insights for future experimental analyses. This broadens our understanding of the various contributing factors involved in modifying jet substructures.
↳ hep-phhep-exnucl-exnucl-thPoS(2024)·0 citations
16
System size dependence of pre-equilibrium and applicability of hydrodynamics in heavy-ion collisions
Victor E. Ambruş🇵🇱 · Sören Schlichting🇷🇴 · Clemens Werthmann🇩🇪
We simulate the space-time dynamics of high-energy collisions based on a microscopic kinetic description, in order to determine the range of applicability of an effective description in relativistic viscous hydrodynamics. We find that hydrodynamics provides a quantitatively accurate description of collective flow when the average inverse Reynolds number $Re^{- 1}$ is sufficiently small and the early pre-equilibrium stage is properly accounted for. By determining the breakdown of hydrodynamics as a function of system size and energy, we find that it is quantitatively accurate in central lead-lead collisions at LHC energies, but should not be used in typical proton-lead or proton-proton collisions, where the development of collective flow can not accurately be described within hydrodynamics.
↳ hep-phnucl-thPoS(2024)·4 citations
17
Longitudinal flow decorrelation in heavy-ion collision at RHIC energies using a multi-phase transport model
Prabhupada Dixit · Md. Nasim
We present a study on the longitudinal flow decorrelation in heavy-ion collisions at the RHIC Beam Energy Scan (BES) energies ( $s_{N N}$ = 11.5 to 200 GeV in Au+Au collisions) using the AMPT model. We measure the second and third order factorization ratios ( $r_{2}$ and $r_{3}$ ) across BES energies, finding $r_{2}$ weakly dependent on collision energy while $r_{3}$ shows a more prominent collision energy dependent. The effect of parton-parton scattering cross section on $r_{2}$ and $r_{3}$ is studied which suggests that longitudinal decorrelation could be a potential observable to constrain transport properties of the medium. We also analyze the contributions of flow-plane and flow magnitude decorrelation, with flow-plane decorrelation being dominant. we measure a recently proposed observable, the four particle cumulant ( $T_{2}$ ), which remains resilient to non-flow effects and exhibits sensitivity to different decorrelation patterns. Through the measurement of $T_{2}$ , we consistently observe a hint of S-shaped or torqued decorrelation across all energy ranges in peripheral collisions (40-80\%). But in central and mid-central collisions, presence of any specific pattern of decorrelation is missing in AMPT model.
↳ hep-phhep-exnucl-th2 citations
18
Artificial Intelligence for the Electron Ion Collider (AI4EIC)
C. Allaire · R. Ammendola · E.-C. Aschenauer · M. Balandat · M. Battaglieri · J. Bernauer · M. Bondì · N. Branson · T. Britton · A. Butter · I. Chahrour · P. Chatagnon and 84 other authors
The Electron-Ion Collider (EIC), a state-of-the-art facility for studying the strong force, is expected to begin commissioning its first experiments in 2028. This is an opportune time for artificial intelligence (AI) to be included from the start at this facility and in all phases that lead up to the experiments. The second annual workshop organized by the AI4EIC working group, which recently took place, centered on exploring all current and prospective application areas of AI for the EIC. This workshop is not only beneficial for the EIC, but also provides valuable insights for the newly established ePIC collaboration at EIC. This paper summarizes the different activities and R&D projects covered across the sessions of the workshop and provides an overview of the goals, approaches and strategies regarding AI/ML in the EIC community, as well as cutting-edge techniques currently studied in other experiments.
↳ physics.acc-phcs.LGhep-exnucl-ex+1Comput.Softw.Big Sci.(2024)·30 citations
19
Magnetic polarizability of a charged pion from four-point functions in lattice QCD
Frank X. Lee🇺🇸 · Walter Wilcox🇺🇸 · Andrei Alexandru🇺🇸 · Chris Culver🇬🇧
Electromagnetic dipole polarizabilities are fundamental properties of a hadron that represent its resistance to deformation under external fields. For a charged hadron, the presence of acceleration and Landau levels complicates the isolation of its deformation energy in the conventional background field method. In this work, we explore a general method based on four-point functions in lattice QCD that takes into account all photon, quark and gluon interactions. The electric polarizability ( $α_{E}$ ) has been determined from the method in a previous proof-of-principle simulation. Here we focus on the magnetic polarizability ( $β_{M}$ ) using the same quenched Wilson action on a $2 4^{3} \times 48$ lattice at $β = 6.0$ with pion mass from 1100 to 370 MeV. The results from the connected diagrams show a large cancellation between the elastic and inelastic contributions, leading to a relatively small and negative value for $β_{M}$ consistent with chiral perturbation theory. We also discuss the mechanism for $α_{E} + β_{M}$ from combining the two studies.
↳ hep-latnucl-thPRD(2023)·11 citations

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