Nuclear Theory·nucl-th

Monday·October 17, 2022

12 papers—5 primary·7 cross-listed

01
[Submitted on 13 Oct 2022]
Optical potentials for the rare-isotope beam era
C. Hebborn🇺🇸 · F. M. Nunes🇺🇸 · G. Potel🇺🇸 · W. H. Dickhoff🇺🇸 · J. W. Holt🇺🇸 · M. C. Atkinson🇺🇸 · R. B. Baker🇺🇸 · C. Barbieri🇮🇹 · G. Blanchon🇫🇷 · M. Burrows🇺🇸 · R. Capote🇦🇹 · P. Danielewicz🇺🇸 and 17 other authors
We review recent progress and motivate the need for further developments in nuclear optical potentials that are widely used in the theoretical analysis of nucleon elastic scattering and reaction cross sections. In regions of the nuclear chart away from stability, which represent a frontier in nuclear science over the coming decade and which will be probed at new rare-isotope beam facilities worldwide, there is a targeted need to quantify and reduce theoretical reaction model uncertainties, especially with respect to nuclear optical potentials. We first describe the primary physics motivations for an improved description of nuclear reactions involving short-lived isotopes, focusing on its benefits for fundamental science discoveries and applications to medicine, energy, and security. We then outline the various methods in use today to build optical potentials starting from phenomenological, microscopic, and ab initio methods, highlighting in particular the strengths and weaknesses of each approach. We then discuss publicly-available tools and resources facilitating the propagation of recent progresses in the field to practitioners. Finally, we provide a set of open challenges and recommendations for the field to advance the fundamental science goals of nuclear reaction studies in the rare-isotope beam era.
Comments:
This paper is the outcome of the Facility for Rare Isotope Beams Theory Alliance (FRIB - TA) topical program "Optical Potentials in Nuclear Physics" held in March 2022 at FRIB. Its content is non-exhaustive, was chosen by the participants and reflects their efforts related to optical potentials
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2210.07293 [pdf]
J.Phys.G(2023)·76 citations
02
[Submitted on 13 Oct 2022]
Light-nuclei production in heavy-ion collisions within a thermodynamical approach
M. Kozhevnikova🇷🇺 · Yu. B. Ivanov🇷🇺
We present results of simulations of light-nuclei production in relativistic heavy-ion collisions within updated Three-fluid Hydrodynamics-based Event Simulator Extended by UrQMD (Ultra-relativistic Quantum Molecular Dynamics) final State interactions (THESEUS). The simulations were performed for Pb+Pb and Au+Au collisions in the collision energy range of $s_{N N} =$ 6.4--19.6 GeV. The light-nuclei production is treated within the thermodynamical approach on equal basis with hadrons. The only additional parameter related to the light nuclei is the energy density of late freeze-out that imitates afterburner stage of the collision because the light nuclei do not participate in the UrQMD evolution. This parameter is fixed from the condition of the best reproduction of the proton transverse-momentum spectrum after the UrQMD afterburner by that at the late freeze-out. The updated THESEUS results in not perfect, but a reasonable reproduction of data on bulk observables of the light nuclei, especially their functional dependence on the collision energy and light-nucleus mass. Various ratios, $d / p$ , $t / p$ , $t / d$ , and $N (t) \times N (p) / N^{2} (d)$ , are also considered. The directed flow of light nuclei turns out to be more involved. Apparently, it requires explicit treatment of the afterburner evolution of light nuclei that violates the kinetic equilibrium. Imperfect reproduction of the light-nuclei data leaves room for medium effects in produced light nuclei.
Comments:
12 pages, 11 figures. Version published in PRC, discussion extended
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2210.07334 [pdf]
PRC(2023)·5 citations
03
[Submitted on 14 Oct 2022]
Spheroidal expansion and freeze-out geometry of heavy-ion collisions in the few-GeV energy regime
Szymon Harabasz🇩🇪 · Jędrzej Kołaś🇵🇱 · Radosław Ryblewski🇵🇱 · Wojciech Florkowski🇵🇱 · Tetyana Galatyuk🇩🇪 · Małgorzata Gumberidze🇩🇪 · Piotr Salabura🇵🇱 · Joachim Stroth🇩🇪 · Hanna Paulina Zbroszczyk🇵🇱
A spheroidal model of the expansion of hadronic matter produced in heavy-ion collisions in the few-GeV energy regime is proposed. It constitutes an extension of the spherically symmetric Siemens-Rasmussen blast-wave model used in our previous works. The spheroidal form of the expansion, combined with a single-freeze-out scenario, allows for a significantly improved description of both the transverse-mass and the rapidity distributions of the produced particles. With the model parameters determined by the hadronic abundances and spectra, we make further predictions of the pion HBT correlation radii that turn out to be in a qualitative agreement with the measured ones. The overall successful description of the data supports the concept of spheroidal symmetry of the produced hadronic systems in this energy range.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2210.07694 [pdf]
PRC(2023)·6 citations
04
[Submitted on 14 Oct 2022]
Resolving the $R_{pA}$ and $v_{2}$ puzzle of $D^{0}$ mesons in $p -$ Pb collisions at the LHC
Chao Zhang🇺🇸 · Liang Zheng🇨🇳 · Shusu Shi🇨🇳 · Zi-Wei Lin🇺🇸
It has been a challenge to understand the experimental data on both the nuclear modification factor and elliptic flow of $D^{0}$ mesons in $p -$ Pb collisions at LHC energies. In this work, we study these collisions with an improved multi-phase transport model. By including the Cronin effect (i.e., transverse momentum broadening) and independent fragmentation for charm quarks, we provide the first simultaneous description of the $D^{0}$ meson $R_{pA}$ and $v_{2}$ data at $p_{T} \leq 8$ GeV $/ c$ . The model also reasonably describes the $D^{0}$ meson $p_{T}$ spectra and the low- $p_{T}$ charged hadron spectra, $R_{pA}$ and $v_{2}$ . Our results show that both parton interactions and the Cronin effect are important for the $D^{0}$ meson $R_{pA}$ , while parton interactions are mostly responsible for the $D^{0}$ meson $v_{2}$ . It is thus essential to include the Cronin effect for the simultaneous description of the $D^{0}$ meson $R_{pA}$ and $v_{2}$ . This work implies that the Cronin effect could also be important for heavy hadrons in large systems.
Comments:
6 pages, 3 figures, the Cronin strength is reduced, comparisons with the HVQMNR code are corrected
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2210.07767 [pdf]
PLB(2023)·24 citations
05
[Submitted on 14 Oct 2022]
Scales in light-nuclei production near the QCD critical point
Shanjin Wu🇨🇳 · Koichi Murase🇯🇵 · Huichao Song🇨🇳
Based on the coalescence model, we analyse the light-nuclei production near the critical point by expanding the phase-space distribution function $f (r, p)$ in terms of the phase-space cumulants $\sim ⟨ r^{m} p^{m} ⟩_{c}$ . We show that the dominant contribution of the phase-space distribution to the yield of light nuclei is determined by the second-order phase-space cumulants. Here, we identify the fireball size, the homogeneity length, and the effective temperature, which are encoded in the second-order phase-space cumulants, as the relevant scales in explaining the yield of light nuclei. These scales are typically much larger than the correlation length of the critical fluctuations created in the rapid expansion of the heavy-ion systems, so we need to eliminate this dominant contribution of the relevant scales in order to isolate the critical contribution from the yield of light nuclei. We find that the second-order phase-space cumulants appeared in the yields of light-nuclei with different mass numbers share a similar structure. This property allows us to construct ratios of light-nuclei yields in appropriate combinations so that the effect of the relevant scales of the light-nuclei yield cancels, which isolates the critical effects.
Comments:
5 pages. Contribution to The Tenth Annual Conference on Large Hadron Collider Physics (LHCP2022)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2210.07841 [pdf]
PoS(2023)·1 citation
06
[Submitted on 13 Oct 2022] (cross-list from cond-mat.quant-gas)
Direct observation of hydrodynamization and local prethermalization
Yuan Le · Yicheng Zhang · Sarang Gopalakrishnan · Marcos Rigol · David S. Weiss
Hydrodynamics accurately describes relativistic heavy-ion collision experiments well before local thermal equilibrium is established. This unexpectedly rapid onset of hydrodynamics -- which takes place on the fastest available timescale -- is called hydrodynamization. It occurs when an interacting quantum system is quenched with an energy density that is much greater than its initial energy density. During hydrodynamization, energy gets redistributed across very different energy scales. Hydrodynamization precedes local equilibration among momentum modes, which is local prethermalization to a generalized Gibbs ensemble in nearly integrable systems or local thermalization in non-integrable systems. Many theories of quantum dynamics postulate local (pre)thermalization, but the associated timescale has not been quantitatively studied. Here we use an array of 1D Bose gases to directly observe both hydrodynamization and local prethermalization. After we apply a Bragg scattering pulse, hydrodynamization is evident in the fast redistribution of energy among distant momentum modes, which occurs on timescales associated with the Bragg peak energies. Local prethermalization can be seen in the slower redistribution of occupation among nearby momentum modes. We find that the time scale for local prethermalization in our system is inversely proportional to the momenta involved. During hydrodynamization and local prethermalization, existing theories cannot quantitatively model our experiment. Exact theoretical calculations in the Tonks-Girardeau limit show qualitatively similar features.
Comments:
28 pages, 4 main figures, 8 extended data figures
Subjects:
Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph); Quantum Physics (quant-ph)
arXiv:
2210.07318 [pdf]
Nature(2023)·36 citations
07
[Submitted on 14 Oct 2022] (cross-list from hep-ph)
Schwinger-Dyson truncations in the all-soft limit: a case study
A. C. Aguilar🇧🇷 · M. N. Ferreira🇪🇸 · B. M. Oliveira🇧🇷 · J. Papavassiliou🇪🇸
We study a special Schwinger-Dyson equation in the context of a pure SU(3) Yang-Mills theory, formulated in the background field method. Specifically, we consider the corresponding equation for the vertex that governs the interaction of two background gluons with a ghost-antighost pair. By virtue of the background gauge invariance, this vertex satisfies a naive Slavnov-Taylor identity, which is not deformed by the ghost sector of the theory. In the all-soft limit, where all momenta vanish, the form of this vertex may be obtained exactly from the corresponding Ward identity. This special result is subsequently reproduced at the level of the Schwinger-Dyson equation, by making extensive use of Taylor's theorem and exploiting a plethora of key relations, particular to the background field method. This information permits the determination of the error associated with two distinct truncation schemes, where the potential advantage from employing lattice data for the ghost dressing function is quantitatively assessed.
Comments:
29 pages, 9 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2210.07429 [pdf]
EPJC(2022)·6 citations
08
[Submitted on 14 Oct 2022] (cross-list from hep-ph)
Bethe-Salpeter Bound-State Solutions: Examining Semirelativistic Approaches
Wolfgang Lucha🇦🇹
Within the formalism of relativistic quantum field theory an adequate framework for the description of two-particle bound states, such as, for instance, all conventional (i.e., non-exotic) mesons, is provided by the Poincaré-covariant homogeneous Bethe-Salpeter equation. In applications, however, this approach usually proves to be rather involved, whence it is not always quite easy to extract the predictions sought. In view of this, a coarse idea of the bound-state spectrum to be expected might be gained by adhering to some simplifying approximations - which constitutes an entirely legitimate first step. The reliability of the insights inferred from the arising simpler bound-state equation may be straightforwardly examined by taking into account a couple of rigorous constraints on the obtained discrete spectrum. Application of these tools is illustrated for popular potentials.
Comments:
8 pages, 2 figures, contributed to "XVth Quark Confinement and the Hadron Spectrum" (1 - 6 August 2022, Stavanger, Norway)
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2210.07720 [pdf]
EPJ Web Conf.(2022)·0 citations
09
[Submitted on 14 Oct 2022] (cross-list from hep-lat)
Thermal Transitions in Dense Two-Colour QCD
Dale Lawlor🇮🇪 · Simon Hands🇬🇧 · Seyong Kim🇰🇷 · Jon-Ivar Skullerud🇮🇪
The infamous sign problem makes it impossible to probe dense (baryon density $μ_{B} > 0$ ) QCD at temperatures near or below the deconfinement threshold. As a workaround, one can explore QCD-like theories such as two-colour QCD (QC2D) which don't suffer from this sign problem but are qualitively similar to real QCD. Previous studies on smaller lattice volumes have investigated deconfinement and colour superfluid to normal matter transitions. In this study we look at a larger lattice volume $N_{s} = 24$ in an attempt to disentangle finite volume and finite temperature effects. We also fit to a larger number of diquark sources to better allow for extrapolation to zero diquark source.
Comments:
7 pages, 9 figures, 1 table, contributed poster presented at XVth Quark Confinement and the Hadron Spectrum conference
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2210.07731 [pdf]
EPJ Web Conf.(2022)·3 citations
10
[Submitted on 14 Oct 2022] (cross-list from cond-mat.str-el)
Addressing energy density functionals in the language of path-integrals II: Comparative study of functional renormalization group techniques applied to the (0+0)-D $O (N)$ -symmetric $φ^{4}$ -theory
Kilian Fraboulet🇩🇪 · Jean-Paul Ebran🇫🇷
The present paper is the second of a series of publications that aim at investigating relevant directions to turn the nuclear energy density functional (EDF) method as an effective field theory (EFT). The EDF approach has known numerous successes in nuclear theory over the past decades and is currently the only microscopic technique that can be applied to all atomic nuclei. However, the phenomenological character of the EDF method also comes with important limitations, such as the lack of an explicit connection with quantum chromodynamics (QCD). As was argued in the first paper of this series, reformulating the EDF framework as an EFT would enable us to overcome these limitations. In particular, path-integral (PI) techniques are suited to achieve such a purpose as they allow to design numerous non-perturbative approximations and can take Lagrangians possibly derived from EFTs of QCD as inputs. In our previous paper, we have illustrated such technical features for diagrammatic PI techniques in a study of the (0+0)-D $O (N)$ -symmetric $φ^{4}$ -theory. In the present work, we consider another class of PI techniques, i.e. functional renormalization group (FRG) approaches, that we apply to the same toy model. Despite our explicit interest for the nuclear many-body problem, the presented study is also directed towards FRG practitioners from various fields: technical details are provided for FRG techniques based on 1-particle-irreducible (1PI), 2-particle-irreducible (2PI) and 2-particle-point-irreducible (2PPI) effective actions (EAs), coined respectively as 1PI-, 2PI- and 2PPI-FRGs, and the treatment of the $O (N)$ symmetry is also addressed thoroughly. Connections between these various FRG methods are identified as well.
Comments:
This article is part of a PhD project. The corresponding manuscript can be found at: arXiv:2210.16676
Subjects:
Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th)
arXiv:
2210.07748 [pdf]
EPJA(2024)·4 citations
11
[Submitted on 14 Oct 2022] (cross-list from hep-ph)
Pushing forward jet substructure measurements in heavy-ion collisions
Daniel Pablos🇮🇹 · Alba Soto-Ontoso🇫🇷
Energetic jets that traverse the quark-gluon plasma created in heavy-ion collisions serve as excellent probes to study this new state of deconfined QCD matter. Presently, however, our ability to achieve a crisp theoretical interpretation of the crescent number of jet observables measured in experiments is hampered by the presence of selection biases. The aim of this work is to minimise those selection biases associated to the modification of the quark- vs. gluon-initiated jet fraction in order to assess the presence of other medium-induced effects, namely color decoherence, by exploring the rapidity dependence of jet substructure observables. So far, all jet substructure measurements at mid-rapidity have shown that heavy-ion jets are narrower than vacuum jets. We show both analytically and with Monte Carlo simulations that if the narrowing effect persists at forward rapidities, where the quark-initiated jet fraction is greatly increased, this could serve as an unambiguous experimental observation of color decoherence dynamics in heavy-ion collisions.
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2210.07901 [pdf]
PRD(2023)·30 citations
12
[Submitted on 14 Oct 2022] (cross-list from hep-ph)
Single diffractive hard exclusive processes for the study of generalized parton distributions
Jian-Wei Qiu🇺🇸 · Zhite Yu🇺🇸
Generalized parton distributions (GPDs) are important nonperturbative functions that provide tomographic images of partonic structures of hadrons. We introduce a type of exclusive processes, to be referred to as single diffractive hard exclusive processes (SDHEPs). We discuss the necessary and sufficient conditions for SDHEPs to be factorized into GPDs. We demonstrate that the SDHEP is not only sufficiently generic to cover all known processes for extracting GPDs, but is also well motivated for the search of new processes for the study of GPDs. We examine the sensitivity of the SDHEP to the parton momentum fraction $x$ dependence of GPDs.
Comments:
26 pages, 26 figures. To match the journal version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2210.07995 [pdf]
PRD(2023)·82 citations

Affiliations

first authorsco-authorsvia INSPIRE