Nuclear Theory·nucl-th

Friday·July 28, 2023

17 papers—8 primary·9 cross-listed

09
[Submitted on 26 Jul 2023] (cross-list from astro-ph.SR)
Nuclear Reactions in Evolving Stars
Friedrich-Karl Thielemann · Thomas Rauscher
This chapter will go through the important nuclear reactions in stellar evolution and explosions, passing through the individual stellar burning stages and also explosive burning conditions. To follow the changes in the composition of nuclear abundances requires the knowledge of the relevant nuclear reaction rates. For light nuclei (entering in early stellar burning stages) the resonance density is generally quite low and the reactions are determined by individual resonances, which are best obtained from experiments. For intermediate mass and heavy nuclei the level density is typically sufficient to apply statistical model approaches. For this reason, while we discuss all burning stages and explosive burning, focusing on the reactions of importance, we will for light nuclei refer to the chapters by M. Wiescher, deBoer & Reifarth (Experimental Nuclear Astrophysics) and P. Descouvement (Theoretical Studies of Low-Energy Nuclear Reactions), which display many examples, experimental methods utilized, and theoretical approaches how to predict nuclear reaction rates for light nuclei. For nuclei with sufficiently high level densities we discuss statistical model methods used in present predictions of nuclear reaction cross sections and thermonuclear rates across the nuclear chart, including also the application to nuclei far from stability and fission modes.
Comments:
invited contribution on "Nuclear Reactions in Evolving Stars" for the Handbook of Nuclear Physics, 55 pages, 19 figures,
Subjects:
Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
2307.14391 [pdf]
Handbook of Nuclear Physics 2023·3 citations
10
[Submitted on 26 Jul 2023] (cross-list from hep-ph)
Axial-vector transition form factors and $e^{+} e^{-} \to f_{1} π^{+} π^{-}$
Martin Hoferichter🇨🇭 · Bastian Kubis🇩🇪 · Marvin Zanke🇩🇪
We study the transition form factors (TFFs) of axial-vector mesons in the context of currently available experimental data, including new constraints from $e^{+} e^{-} \to f_{1} (1285) π^{+} π^{-}$ that imply stringent limits on the high-energy behavior and, for the first time, allow us to provide an unambiguous determination of the couplings corresponding to the two antisymmetric TFFs. We discuss how these constraints can be implemented in a vector-meson-dominance picture, and, in combination with contributions from the light-cone expansion, construct TFFs as input for the evaluation of axial-vector contributions to hadronic light-by-light scattering in the anomalous magnetic moment of the muon.
Comments:
28 pages, 4 figures; journal version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2307.14413 [pdf]
JHEP(2023)·65 citations
11
[Submitted on 26 Jul 2023] (cross-list from hep-ph)
Heavy neutron stars from light scalars
Reuven Balkin🇮🇱 · Javi Serra🇪🇸 · Konstantin Springmann🇩🇪 · Stefan Stelzl🇨🇭 · Andreas Weiler🇩🇪
We study how light scalar fields can change the stellar landscape by triggering a new phase of nuclear matter. Scalars coupled to nucleons can develop a non-trivial expectation value at finite baryon density. This sourcing of a scalar reduces the nucleon mass and provides an additional energy density and pressure source. Under generic conditions, a new ground state of nuclear matter emerges, with striking implications for the configuration of stellar remnants. Notably, neutron stars in the new ground state can be significantly heavier than QCD equations of state currently predict. We also find hybrid stellar compositions and stable self-bound objects with sizes as small as the Compton wavelength of the scalar. We discuss several specific realizations of this scenario: the QCD axion and lighter generalizations thereof and linearly or quadratically coupled scalar fields effectively equivalent to a class of scalar-tensor modification of gravity. Lastly, we explore phenomenological signatures relevant to electromagnetic and gravitational wave observations of neutron stars, such as atypical compactness and instability gaps in radii.
Comments:
56 pages, 11 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
2307.14418 [pdf]
JHEP(2025)·51 citations
12
[Submitted on 26 Jul 2023] (cross-list from hep-ph)
Fluid dynamics of charm quarks in the quark--gluon plasma
Federica Capellino🇩🇪 · Andrea Dubla🇩🇪 · Stefan Floerchinger🇺🇸 · Eduardo Grossi🇮🇹 · Andreas Kirchner🇩🇪 · Silvia Masciocchi🇩🇪
A fluid-dynamic approach to charm-quark diffusion in the quark-gluon plasma (QGP) is developed for the first time. Results for integrated yields and momentum distributions of charmed hadrons obtained with a fluid-dynamic description for the dynamics of the QGP coupled to an additional heavy-quark-antiquark current are shown. In addition to the thermodynamic Equation of State (EoS), this description uses a heavy-quark diffusion constant which we take from Lattice QCD calculations. The results describe quantitatively experimental data measured at the LHC at the center-of-mass energy of $s_{NN}$ = 5.02 TeV up to $p_{T} \sim$ 4-5 GeV/ $c$ , showing that charm quarks undergo a very fast hydrodynamization in the medium created by ultrarelativistic heavy-ion collisions.
Comments:
11 pages, 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2307.14449 [pdf]
PRD(2023)·27 citations
13
[Submitted on 27 Jul 2023] (cross-list from hep-ph)
Possible formation of Quark-Gluon Plasma in small collision systems at the Large Hadron Collider: Observations and Challenges
Raghunath Sahoo🇮🇳
With the advent of unprecedented collision energy at the Large Hadron Collider, CERN, Geneva, a new domain of particle production and possible formation of Quark-Gluon Plasma (QGP) in high-multiplicity proton-proton collisions and the collisions of light nuclei has been a much-discussed topic recently. In this review, I discuss some of the recent observations leading to such a possibility, associated challenges, and some predictions for the upcoming light-nuclei collisions at the LHC.
Comments:
DAE-HEP Symposium, 2022 Proceedings of the mini-review. To be published in Springer Nature Proceedings
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2307.14665 [pdf]
Springer Proc.Phys.(2024)·2 citations
14
[Submitted on 27 Jul 2023] (cross-list from hep-lat)
Confronting axial-vector form factor from lattice QCD with MINERvA antineutrino-proton data
Oleksandr Tomalak🇺🇸 · Rajan Gupta🇺🇸 · Tanmoy Bhattacharya🇺🇸
We compare recent MINERvA antineutrino-hydrogen charged-current measurements to phenomenological predictions of the axial-vector form factor based on fits to all available electron scattering and deuterium bubble-chamber data and to representative lattice-QCD (LQCD) determination by the PNDME Collaboration. While there is $1$ -- $2 σ$ agreement in the cross section with MINERvA data for each bin in $Q^{2}$ , we identify three regions with different relevance and opportunity for LQCD predictions. For $Q^{2} ≲ 0.2 GeV^{2}$ , the phenomenological extractions have large number of data points and LQCD is competitive, while MINERvA data have large errors. For $0.2 GeV^{2} ≲ Q^{2} ≲ 1 GeV^{2}$ , LQCD is competitive with the MINERvA determination, and both give values larger than from phenomenological extraction. For $Q^{2} > 1 GeV^{2}$ , the MINERvA data are the most precise. Our analysis indicates that with improving precision of MINERvA-like experiments and LQCD data, the uncertainty in the nucleon axial-vector form factor will be steadily reduced.
Comments:
7 pages, 4 figures, v2: version published in Physical Review D, minor changes in text and figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2307.14920 [pdf]
PRD(2023)·27 citations
15
[Submitted on 27 Jul 2023] (cross-list from hep-ph)
Single inclusive particle production at next-to-leading order in proton-nucleus collisions at forward rapidities: hybrid approach meets TMD factorization
Tolga Altinoluk🇵🇱 · Néstor Armesto🇪🇸 · Alexander Kovner🇺🇸 · Michael Lublinsky🇮🇱
We revisit the calculation of the cross section for forward inclusive single hadron production in $p A$ collisions within the hybrid approach. We show that the proper framework to perform this calculation beyond leading order is not the collinear factorization, as has been assumed so far, but the TMD factorized framework. Within the TMD factorized approach we show that all the large transverse logarithms appearing in the fixed order calculation, are resummed into the evolution of the TMD PDFs and TMD FFs with factorization scale. The resulting expressions, when written in terms of TMDs evolved to the appropriate, physically well understood factorization scale, contain no additional large logarithms. The absence of any large logarithms in the resummed result should ensure positivity of the cross section and eradicate the persistent problem that have plagued the previous attempts at calculating this observable in the hybrid approach.
Comments:
LaTeX, 39 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2307.14922 [pdf]
PRD(2023)·15 citations
16
[Submitted on 27 Jul 2023] (cross-list from hep-th)
Helical Separation Effect and helical heat transport for Dirac fermions
Victor E. Ambruş🇷🇴 · Maxim N. Chernodub🇫🇷
An ensemble of massless fermions can be characterized by its total helicity charge given by the sum of axial charges of particles minus the sum of axial charges of antiparticles. We show that charged massless fermions develop a dissipationless flow of helicity along the background magnetic field. We dub this transport phenomenon as the Helical Separation Effect (HSE). Contrary to its chiral cousin, the Chiral Separation Effect, the HSE produces the helical current in a neutral plasma in which all chemical potentials vanish. In addition, we uncover the Helical Magnetic Heat Effect which generates a heat flux of Dirac fermions along the magnetic field in the presence of non-vanishing helical charge density. We also discuss possible hydrodynamic modes associated with the HSE in neutral plasma.
Comments:
17 pages
Subjects:
High Energy Physics — Theory (hep-th); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Nuclear Theory (nucl-th)
arXiv:
2307.14987 [pdf]
EPJC(2024)·3 citations
17
[Submitted on 27 Jul 2023] (cross-list from hep-lat)
Lattice quantum chromodynamics at large isospin density: 6144 pions in a box
Ryan Abbott🇺🇸 · William Detmold🇺🇸 · Fernando Romero-López🇺🇸 · Zohreh Davoudi🇺🇸 · Marc Illa🇺🇸 · Assumpta Parreño🇪🇸 · Robert J. Perry🇪🇸 · Phiala E. Shanahan🇺🇸 · Michael L. Wagman🇺🇸
We present an algorithm to compute correlation functions for systems with the quantum numbers of many identical mesons from lattice quantum chromodynamics (QCD). The algorithm is numerically stable and allows for the computation of $n$ -pion correlation functions for $n \in {1, \dots, N}$ using a single $N \times N$ matrix decomposition, improving on previous algorithms. We apply the algorithm to calculations of correlation functions with up to 6144 $π^{+}$ s using two ensembles of gauge field configurations generated with quark masses corresponding to a pion mass $m_{π} = 170$ MeV and spacetime volumes of $(4. 4^{3} \times 8.8) fm^{4}$ and $(5. 8^{3} \times 11.6) fm^{4}$ . We also discuss statistical techniques for the analysis of such systems, in which the correlation functions vary over many orders of magnitude. In particular, we observe that the many-pion correlation functions are well approximated by log-normal distributions, allowing the extraction of the energies of these systems. Using these energies, the large-isospin-density, zero-baryon-density region of the QCD phase diagram is explored. A peak is observed in the energy density at an isospin chemical potential $μ_{I} \sim 1.5 m_{π}$ , signalling the transition into a Bose-Einstein condensed phase. The isentropic speed of sound in the medium is seen to exceed the ideal-gas (conformal) limit ( $c_{s}^{2} \leq 1/3$ ) over a wide range of chemical potential before falling towards the asymptotic expectation at $μ_{I} \sim 15 m_{π}$ . These, and other thermodynamic observables, indicate that the isospin chemical potential must be large for the system to be well described by an ideal gas or perturbative QCD.
Comments:
16 pages, 18 figures, 1 table
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2307.15014 [pdf]
PRD(2023)·80 citations

Affiliations

first authorsco-authorsvia INSPIRE