Nuclear Theory·nucl-th

Wednesday·June 21, 2023

18 papers—8 primary·10 cross-listed

09
[Submitted on 16 Jun 2023] (cross-list from hep-ph)
Quark mass difference effects in hadronic Fermi matrix elements from first principles
Chien-Yeah Seng🇺🇸 · Vincenzo Cirigliano🇺🇸 · Xu Feng🇨🇳 · Mikhail Gorchtein🇩🇪 · Luchang Jin🇺🇸 · Gerald A. Miller🇺🇸
It was recently estimated that the strong isospin-symmetry breaking (ISB) corrections to the Fermi matrix element in free neutron decay could be of the order $1 0^{- 4}$ , one order of magnitude larger than the na\"ıve estimate based on the Behrends-Sirlin-Ademollo-Gatto theorem. To investigate this claim, we derive a general expression of the leading ISB correction to hadronic Fermi matrix elements, which takes the form of a four-point correlation function in lattice gauge theory and is straightforward to compute from first principles. Our formalism paves the way for the first determination of such correction in the neutron sector with fully-controlled theory uncertainties.
Comments:
Version accepted by PLB
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2306.10199 [pdf]
PLB(2023)·7 citations
10
[Submitted on 17 Jun 2023] (cross-list from hep-th)
Skyrmions at Finite Density
Fabrizio Canfora🇨🇱 · Scarlett C. Rebolledo-Caceres🇨🇱
In this paper, we will describe recent advances in analytical methods to construct exact solutions of the Skyrme model (and its generalizations) representing inhomogeneous Hadronic condensates living at finite Baryon density. Such novel analytical tools are based on the idea to generalize the well known spherical hedgehog ansatz to situations (relevant for the analysis of finite density effects) in which there is no spherical symmetry anymore. Besides the intrinsic mathematical interest to find exact solutions with non-vanishing Baryonic charge confined to a finite volume, this framework opens the possibility to compute important physical quantities which would be difficult to compute otherwise.
Comments:
Accepted for publication in MPLA; 33 pages, 2 figures. V2: references added
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2306.10226 [pdf]
Mod.Phys.Lett.A(2023)·4 citations
11
[Submitted on 17 Jun 2023] (cross-list from hep-ph)
Core-corona procedure and microcanonical hadronization to understand strangeness enhancement in proton-proton and heavy ion collisions in the EPOS4 framework
K. Werner🇫🇷
The multiplicity dependence of multistrange hadron yields in proton-proton and lead-lead collisions at several TeV allows one to study the transition from very big to very small systems, in particular, concerning collective effects. I investigate this, employing a core-corona approach based on new microcanonical hadronization procedures in the EPOS4 framework, as well as new methods allowing one to transform energy-momentum flow through freeze-out surfaces into invariant-mass elements. I try to disentangle effects due to ``canonical suppression'' and ``core-corona separation'', which will both lead to a reduction of the yields at low multiplicity.
Comments:
27 pages, 32 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2306.10277 [pdf]
PRC(2024)·72 citations
12
[Submitted on 17 Jun 2023] (cross-list from hep-ph)
Helicity of Quarks and Gluons at Small Bjorken $x$
Yossathorn Tawabutr🇺🇸
The proton spin puzzle is a longstanding problem in high-energy nuclear physics: how the proton spin distributes among the spin and orbital angular momenta of the quarks and gluons inside. Two of the unresolved pieces of the puzzle are the contributions to quark and gluon spins from the region of small Bjorken $x$ . This dissertation fills the gap by constructing the evolution of these quantities into the small- $x$ region using a modified dipole formalism. The dominant contributions to the evolution equations resum powers of $α_{s} ln^{2} (1/ x)$ , where $α_{s}$ is the strong coupling constant. In general, these evolution equations do not close. However, once the large- $N_{c}$ or large- $N_{c} & N_{f}$ limit is taken, they turn into a system of linear integral equations that can be solved iteratively. At large $N_{c}$ , the evolution equations are shown to be consistent with the gluon sector of the polarized DGLAP evolution in the small- $x$ limit. We numerically solve the equations in the large- $N_{c}$ and large- $N_{c} & N_{f}$ limits and obtain the exponential growth in $ln (1/ x)$ for $N_{f} \leq 5$ , with the intercept decreasing with $N_{f}$ . For the large- $N_{c}$ limit, we have $α_{h} = 3.66$ , which agrees up to the uncertainty with the earlier work by Bartels, Ermolaev and Ryskin. Furthermore, at $N_{f} = 6$ , the asymptotic form attains an oscillation in $ln (1/ x)$ on top of the exponential growth, with the period spanning several units of rapidity. Finally, parts of the single-logarithmic corrections to the small- $x$ helicity evolution is also derived, resumming powers of $α_{s} ln (1/ x)$ . There, the effects of the unpolarized small- $x$ evolution and the running coupling are also included for consistency. The complete single-logarithmic corrections can be derived based on the framework established here. Altogether, these equations will provide the most precise small- $x$ helicity evolution to date.
Comments:
Version 2, minor edits based on external suggestions; 237 pages, 67 figures, Ph.D. dissertation
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2306.10361 [pdf]
4 citations
13
[Submitted on 18 Jun 2023] (cross-list from hep-ph)
Effect of finite volume on thermodynamics of quark-hadron matter
Somenath Pal🇮🇳 · Anton Motornenko🇩🇪 · Volodymyr Vovchenko🇩🇪 · Abhijit Bhattacharyya🇮🇳 · Jan Steinheimer🇩🇪 · Horst Stoecker🇩🇪
The effects of a finite system volume on thermodynamic quantities, such as the pressure, energy density, specific heat, speed of sound, conserved charge susceptibilities and correlations, in hot and dense strongly interacting matter are studied within the parity-doublet Chiral Mean Field (CMF) model. Such an investigation is motivated by relativistic heavy-ion collisions, which create a blob of hot QCD matter of a finite volume, consisting of strongly interacting hadrons and potentially deconfined quarks and gluons. The effect of the finite volume of the system is incorporated by introducing a lower momentum cut-offs in the momentum integrals appearing in the model, the numerical value of the momentum cut-off being related to the de Broglie wavelength of the given particle species. It is found that some of these quantities show a significant volume dependence, in particular those sensitive to pion degrees of freedom, and the crossover transition is generally observed to become smoother in finite volume. These findings are relevant for the effective equation of state used in fluid dynamical simulations of heavy-ion collisions and efforts to extract the freeze out properties of heavy-ion collisions with susceptibilities involving electric charge and strangeness.
Comments:
10 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2306.10596 [pdf]
PRD(2024)·8 citations
14
[Submitted on 18 Jun 2023] (cross-list from hep-ph)
Exclusive $η_{c}$ production from small- $x$ evolved Odderon at a electron-ion collider
Sanjin Benić🇭🇷 · Davor Horvatić🇭🇷 · Abhiram Kaushik🇭🇷 · Eric Andreas Vivoda🇭🇷
We compute exclusive $η_{c}$ production in high energy electron-nucleon and electron-nucleus collisions that is sensitive to the Odderon. In perturbative QCD the Odderon is a $C$ -odd color singlet consisting of at least three $t$ -channel gluons exchanged with the target. By using the Color Glass Condensate effective theory our result describes the Odderon exchange at the high collision energies that would be reached at a future electron-ion collider. The Odderon distribution is evolved to small- $x$ using the Balitsky-Kovchegov evolution equation with running coupling corrections. We find that while at low momentum transfers $t$ the cross section off a proton is dominated by the Primakoff process, the Odderon becomes relevant at larger momentum transfers of $∣ t ∣ \geq 1.5$ GeV $^{2}$ . We point that the Odderon could also be extracted at low- $t$ using neutron targets since the Primakoff component is strongly suppressed. In the case of nuclear targets, the Odderon cross section becomes enhanced thanks to the mass number of the nuclear target. The gluon saturation effect induces a shift in the diffractive pattern with respect to the Primakoff process that could be used as a signal for the Odderon.
Comments:
a few typos corrected, a few references added, matches the published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2306.10626 [pdf]
PRD(2023)·18 citations
15
[Submitted on 18 Jun 2023] (cross-list from hep-ph)
Two and three photon fusion into charmonium in ultra-peripheral nuclear collisions
R. Fariello🇧🇷 · D. Bhandari🇺🇸 · C.A. Bertulani🇺🇸 · F.S. Navarra🇺🇸
In this paper we investigate the production of charmonium states in two and three photon fusion processes in nucleus -- nucleus collisions at the CERN Large Hadron Collider (LHC) energies. Our results indicate that the experimental study of these processes is feasible and can be used to constrain the theoretical decay widths and give information on the non $c - c ˉ$ components of these states.
Comments:
7 pages, 3 tables. arXiv admin note: text overlap with arXiv:1610.06604
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2306.10642 [pdf]
PRC(2023)·12 citations
16
[Submitted on 19 Jun 2023] (cross-list from hep-ph)
Distinctive nuclear signatures of low-energy atmospheric neutrinos
Anna M. Suliga🇺🇸 · John F. Beacom🇺🇸
New probes of neutrino mixing are needed to advance precision studies. One promising direction is via the detection of low-energy atmospheric neutrinos (below a few hundred MeV), to which a variety of near-term experiments will have much-improved sensitivity. Here we focus on probing these neutrinos through distinctive nuclear signatures of exclusive neutrino-carbon interactions -- those that lead to detectable nuclear-decay signals with low backgrounds -- in both neutral-current and charged-current channels. The neutral-current signature is a line at 15.11 MeV and the charged-current signatures are two- or three-fold coincidences with delayed decays. We calculate the prospects for identifying such events in the Jiangmen Underground Neutrino Observatory (JUNO), a large-scale liquid-scintillator detector. A five-year exposure would yield about 16 neutral-current events (all flavors) and about 16 charged-current events (mostly from $ν_{e} + ν ˉ_{e}$ , with some from $ν_{μ} + ν ˉ_{μ}$ ), and thus roughly 25\% uncertainties on each of their rates. Our results show the potential of JUNO to make the first identified measurement of sub-100 MeV atmospheric neutrinos. They also are a step towards multi-detector studies of low-energy atmospheric neutrinos, with the goal of identifying additional distinctive nuclear signatures for carbon and other targets.
Comments:
13 pages, 7 figures, 1 appendix. Minor changes, matches version published in Phys. Rev. D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2306.11090 [pdf]
PRD(2023)·10 citations
17
[Submitted on 20 Jun 2023] (cross-list from astro-ph.SR)
The $γ$ -process nucleosynthesis in core-collapse supernovae. I. A novel analysis of $γ$ -process yields in massive stars
L. Roberti · M. Pignatari · A. Psaltis · A. Sieverding · P. Mohr · Zs. Fülöp · M. Lugaro
The $γ$ -process nucleosynthesis in core-collapse supernovae is generally accepted as a feasible process for the synthesis of neutron-deficient isotopes beyond iron. However, crucial discrepancies between theory and observations still exist: the average production of $γ$ -process yields from massive stars are too low to reproduce the solar distribution in galactic chemical evolution calculations, and the yields of the Mo and Ru isotopes are by a further factor of 10 lower than the yields of the other $γ$ -process nuclei. We investigate the $γ$ -process in 5 sets of core-collapse supernova models published in literature with initial masses 15, 20, and 25 M $_{⊙}$ at solar metallicity. We compared the $γ$ -process overproduction factors from the different models. To highlight the possible effect of nuclear physics input, we also considered 23 ratios of two isotopes close to each other in mass, relative to their solar values. Further, we investigated the contribution of C-O shell mergers in the supernova progenitors as an additional site of the $γ$ -process. Our analysis shows that a large scatter among the different models exists for both the $γ$ -process integrated yields and the isotopic ratios. We found only 10 ratios that agree with their solar values, all the others differ by at least a factor of 3 from the solar values in all the considered sets of models. The $γ$ -process within C-O shell mergers mostly influence the isotopic ratios that involve intermediate and heavy proton-rich isotopes with $A > 100$ .
Comments:
Accepted for publication in A&A. 20 pages, 17 figures
Subjects:
Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2306.11409 [pdf]
Astron.Astrophys.(2023)·21 citations
18
[Submitted on 20 Jun 2023] (cross-list from physics.comp-ph)
iQMC: Iterative Quasi-Monte Carlo for k-Eigenvalue Neutron Transport Simulations
Samuel Pasmann · Ilham Variansyah · C.T. Kelley · Ryan G. McClarren
The Iterative Quasi-Monte Carlo method, or iQMC, replaces standard quadrature techniques used in deterministic linear solvers with Quasi-Monte Carlo simulation for more accurate and efficient solutions to the neutron transport equation. This work explores employing iQMC in the Monte-Carlo Dynamic Code (MCDC) to solve k-eigenvalue problems for neutron transport with both the standard power iteration and the generalized Davidson method, a Krylov Subspace method. Results are verified with the 3-D, 2-group, Takeda-1 Benchmark problem.
Subjects:
Computational Physics (physics.comp-ph); Nuclear Theory (nucl-th)
arXiv:
2306.11600 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE