Nuclear Theory·nucl-th

Friday·June 10, 2022

10 papers—4 primary·6 cross-listed

05
[Submitted on 8 Jun 2022] (cross-list from hep-lat)
Pion distribution amplitude at the physical point using the leading-twist expansion of the quasi-distribution-amplitude matrix element
Xiang Gao🇺🇸 · Andrew D. Hanlon🇺🇸 · Nikhil Karthik🇺🇸 · Swagato Mukherjee🇺🇸 · Peter Petreczky🇺🇸 · Philipp Scior🇺🇸 · Sergey Syritsyn🇺🇸 · Yong Zhao🇺🇸
We present a lattice QCD determination of the distribution amplitude (DA) of the pion and the first few Mellin moments from an analysis of the quasi-DA matrix element within the leading-twist framework. We perform our study on a HISQ ensemble with $a = 0.076$ fm lattice spacing with the Wilson-Clover valence quark mass tuned to the physical point. We analyze the ratios of pion quasi-DA matrix elements at short distances using the leading-twist Mellin operator product expansion (OPE) at the next-to-leading order and the conformal OPE at the leading-logarithmic order. We find a robust result for the first non-vanishing Mellin moment $⟨ x^{2} ⟩ = 0.287 (6) (6)$ at a factorization scale $μ = 2$ GeV. We also present different Ansätze-based reconstructions of the $x$ -dependent DA, from which we determine the perturbative leading-twist expectations for the pion electromagnetic and gravitational form-factors at large momentum transfers.
Comments:
26 pages, 13 figures; published version
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2206.04084 [pdf]
PRD(2022)·62 citations
06
[Submitted on 8 Jun 2022] (cross-list from astro-ph.HE)
Time-dependent and quasi-steady features of fast neutrino-flavor conversion
Hiroki Nagakura🇯🇵 · Masamichi Zaizen🇯🇵
Despite the theoretical indication that fast neutrino-flavor conversion (FFC) ubiquitously occurs in core-collapse supernova and binary neutron star merger, the lack of global simulations has been the greatest obstacle to study their astrophysical consequences. In this {\it Letter}, we present large-scale ( $50 km$ ) simulations of FFC in spherical symmetry by using a novel approach. We effectively rescale the oscillation scale of FFC by reducing the number of injected neutrinos in the simulation box, and then extrapolate back to the case of the target density of neutrinos with a convergence study. We find that FFC in all models achieves quasi-steady state in the non-linear regime, and its saturation property of FFC is universal. We also find that temporal- and spatial variations of FFC are smeared out at large radii due to phase cancellation through neutrino self-interactions. Finally, we provide a new diagnostic quantity, ELN-XLN angular crossing, to assess the non-linear saturation of FFC.
Comments:
Accepted for publication in PRL
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2206.04097 [pdf]
PRL(2022)·85 citations
07
[Submitted on 8 Jun 2022] (cross-list from nucl-ex)
The impact of $^{17}$ O $+ α$ reaction rate uncertainties on the s-process in rotating massive stars
J. Frost-Schenk · P. Adsley · A.M. Laird · R. Longland · C. Angus · C. Barton · A. Choplin · C. Aa. Diget · R. Hirschi · C. Marshall · F. Portillo Chaves · K. Setoodehnia
Massive stars are crucial to galactic chemical evolution for elements heavier than iron. Their contribution at early times in the evolution of the Universe, however, is unclear due to poorly constrained nuclear reaction rates. The competing $^{17}$ O( $α, γ$ ) $^{21}$ Ne and $^{17}$ O( $α, n$ ) $^{20}$ Ne reactions strongly impact weak s-process yields from rotating massive stars at low metallicities. Abundant $^{16}$ O absorbs neutrons, removing flux from the s-process, and producing $^{17}$ O. The $^{17}$ O( $α, n$ ) $^{20}$ Ne reaction releases neutrons, allowing continued s-process nucleosynthesis, if the $^{17}$ O( $α, γ$ ) $^{21}$ Ne reaction is sufficiently weak. While published rates are available, they are based on limited indirect experimental data for the relevant temperatures and, more importantly, no uncertainties are provided. The available nuclear physics has been evaluated, and combined with data from a new study of astrophysically relevant $^{21}$ Ne states using the $^{20}$ Ne( $d, p$ ) $^{21}$ Ne reaction. Constraints are placed on the ratio of the ( $α, n$ )/( $α, γ$ ) reaction rates with uncertainties on the rates provided for the first time. The new rates favour the ( $α, n$ ) reaction and suggest that the weak s-process in rotating low-metallicity stars is likely to continue up to barium and, within the computed uncertainties, even to lead.
Comments:
The MNRAS way of doing a sideways table forces a new page but apparently this is a known behaviour
Subjects:
Nuclear Experiment (nucl-ex); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
2206.04167 [pdf]
MNRAS(2022)·8 citations
08
[Submitted on 8 Jun 2022] (cross-list from hep-th)
QED as a many-body theory of worldlines: I. General formalism and infrared structure
Xabier Feal🇺🇸 · Andrey Tarasov🇺🇸 · Raju Venugopalan🇺🇸
We discuss a reformulation of QED in which matter and gauge fields are integrated out explicitly, resulting in a many-body Lorentz covariant theory of 0+1 dimensional worldlines describing super-pairs of spinning charges interacting through Lorentz forces. This provides a powerful, string inspired definition of amplitudes to all loop orders. In particular, one obtains a more general formulation of Wilson loops and lines, with exponentiated dynamical fields and spin precession contributions, and worldline contour averages exactly defined through first quantized path integrals. We discuss in detail the attractive features of this formalism for high order perturbative computations. We show that worldline S-matrix elements, to all loop orders in perturbation theory, can be constructed to be manifestly free of soft singularities, with infrared (IR) divergences captured and removed by endpoint photon exchanges at infinity that are equivalent to the soft coherent dressings of the Dyson S-matrix proposed by Faddeev and Kulish. We discuss these IR structures and make connections with soft theorems, the Abelian exponentiation of IR divergences and cusp anomalous dimensions. Follow-up papers will discuss the efficient computation of cusp anomalous dimensions and universal features of soft theorems.
Comments:
90 pages, 13 figures
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2206.04188 [pdf]
PRD(2022)·17 citations
09
[Submitted on 9 Jun 2022] (cross-list from hep-lat)
Searching for the QCD critical point along the pseudo-critical/freeze-out line using Padé-resummed Taylor expansions of cumulants of conserved charge fluctuations
Jishnu Goswami🇯🇵 · Frithjof Karsch🇩🇪 · Swagato Mukherjee🇺🇸 · Christian Schmidt🇩🇪
Using high-statistics datasets generated in (2+1)-flavor QCD calculations at finite temperature we construct estimators for the radius of convergence from an eighth order series expansion of the pressure as well as the number density. We show that the estimator for pressure and number density will be identical in the asymptotic limit. In the vicinity of the pseudo-critical temperature, $T_{p c} ≃ 156.5$ ~MeV, we find the estimator of the radius of convergence to be $μ_{B} / T ≳ 3$ for strangeness-neutral matter. We also present results for the pole structure of the Padé approximants for the pressure at non-zero values of the baryon chemical potential and show that the pole structure of the [4,4] Padé is consistent with not having a critical point at temperatures larger than $135$ MeV and a baryon chemical potential smaller than $μ_{B} / T \sim 2.5$ .
Comments:
6 pages, prepared for the proceedings of Quark Matter 2022
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2206.04504 [pdf]
Acta Phys.Polon.Supp.(2023)·2 citations
10
[Submitted on 9 Jun 2022] (cross-list from hep-ph)
Chiral condensate from a hadron resonance gas model
Deeptak Biswas🇮🇳 · Peter Petreczky🇺🇸 · Sayantan Sharma🇮🇳
In this work we address the question of how well the chiral crossover transition can be understood in terms of a noninteracting hadron resonance gas model. Using the latest results on the variation of hadron masses as a function of the pion mass from lattice quantum chromodynamics, we study the temperature dependence of the renormalized chiral condensate in 2+1 flavor QCD. Furthermore, we suggest a better criterion to estimate of the pseudocritical temperature, which gives $T_{c} = 161.2 \pm 1.7$ MeV, which is much improved compared to all the earlier results within the hadron resonance gas model or chiral perturbation theory. For the curvature of the pseudocritical line we find $κ_{2} = 0.0203 (7)$ , which is in very good agreement with continuum extrapolated lattice results.
Comments:
v2: published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2206.04579 [pdf]
PRC(2022)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE

Pion distribution amplitude at the physical point using the leading-twist expansion of the quasi-distribution-amplitude matrix element

Time-dependent and quasi-steady features of fast neutrino-flavor conversion

The impact of 17O+α reaction rate uncertainties on the s-process in rotating massive stars

QED as a many-body theory of worldlines: I. General formalism and infrared structure

Searching for the QCD critical point along the pseudo-critical/freeze-out line using Padé-resummed Taylor expansions of cumulants of conserved charge fluctuations

Chiral condensate from a hadron resonance gas model

Affiliations

The impact of $^{17}$ O $+ α$ reaction rate uncertainties on the s-process in rotating massive stars