Nuclear Theory·nucl-th

Thursday·December 12, 2024

9 papers—3 primary·6 cross-listed

04
On the definition of the nucleon axial charge density
J. Yu. Panteleeva🇩🇪 · E. Epelbaum🇩🇪 · J. Gegelia🇩🇪 · U.-G. Meißner🇬🇪
We work out the spatial density distributions corresponding to the axial-vector charge density operator for spin-1/2 systems using states described by sharply localized wave packets in arbitrary Lorentz-frames. The static approximation, leading to the frequently assumed Breit-frame distributions, is also considered. We discuss the interpretation of the resulting spatial densities in terms of the axial charge density.
↳ hep-phnucl-thPLB(2026)·4 citations
05
Channels of Stellar-mass Black Hole Formation
Adam Burrows · Tianshu Wang · David Vartanyan
On the basis of a large collection of detailed 3D core-collapse supernova simulations carried to late times, we identify four channels of stellar mass black hole formation. Our examples for Channel 1 involve the formation of lower-gap and above black holes in energetic asymmetric supernova explosions. Our Channel 2 example involves a modest supernova explosion that may leave behind a lower-gap to $\sim$ 10 $M_{⊙}$ black hole. The latter may not be easily distinguishable from ``standard" supernovae that birth neutron stars. Our Channel 3 example experiences an aborted core-collapse explosion, more often in the context of a low-metallicity progenitor, whose residue is a black hole with a mass perhaps up to $\sim$ 40 $M_{⊙}$ . The latter may be accompanied by a pulsational-pair instability supernova (PPISN). Channel 4 is the only quiescent or ``silent" scenario for which perhaps $\sim$ 5 to 15 $M_{⊙}$ black holes are left. Where appropriate, we estimate $^{56}$ Ni yields, explosion energies, approximate recoil speeds, and residual black hole masses. The progenitor mass density and binding energy profiles at collapse influence the outcome in a systematic way. We speculate that the statistics and prevalence of these various channels depend not only on still evolving supernova theory, but on remaining issues with the theory of massive star evolution, binary interaction, wind mass loss, metallicity, and the nuclear equation of state. Importantly, we suggest, but have not proven, that the silent channel for black hole formation may not be the dominant formation modality.
↳ astro-ph.SRastro-ph.GAastro-ph.HEnucl-th19 citations
06
Symmetry verification for noisy quantum simulations of non-Abelian lattice gauge theories
Edoardo Ballini🇮🇹 · Julius Mildenberger🇮🇹 · Matteo M. Wauters🇮🇹 · Philipp Hauke🇮🇹
Non-Abelian gauge theories underlie our understanding of fundamental forces of modern physics. Simulating them on quantum hardware is an outstanding challenge in the rapidly evolving field of quantum simulation. A key prerequisite is the protection of local gauge symmetries against errors that, if unchecked, would lead to unphysical results. While an extensive toolkit devoted to identifying, mitigating, and ultimately correcting such errors has been developed for Abelian groups, non-commuting symmetry operators complicate the implementation of similar schemes in non-Abelian theories. Here, we discuss two techniques for error mitigation through symmetry verification, tailored for non-Abelian lattice gauge theories implemented in noisy qudit hardware: dynamical post-selection (DPS), based on mid-circuit measurements without active feedback, and post-processed symmetry verification (PSV), which combines measurements of correlations between target observables and gauge transformations. We illustrate both approaches for the discrete non-Abelian group $D_{3}$ in 2+1 dimensions, explaining their usefulness for current NISQ devices even in the presence of fast fluctuating noise. Our results open new avenues for robust quantum simulation of non-Abelian gauge theories, for further development of error-mitigation techniques, and for measurement-based control methods in qudit platforms.
↳ quant-phcond-mat.otherhep-latnucl-thQuantum(2025)·25 citations
07
Melting of $c c ˉ$ and $b b ˉ$ pairs in the pre-equilibrium stage of proton-nucleus collisions at the Large Hadron Collider
Lucia Oliva🇮🇹 · Gabriele Parisi🇮🇹 · Vincenzo Greco🇮🇹 · Marco Ruggieri🇮🇹
We study the melting of $c c ˉ$ and $b b ˉ$ pairs in the early stage of high-energy proton-nucleus collisions. We describe the early stage in terms of an evolving $S U (3)$ glasma stage, that is dominated by intense, out-of-equilibrium gluon fields. On top of these fields, we liberate heavy quark-antiquark pairs, whose constituents are let evolve according to relativistic kinetic theory coupled to the gluon fields. We define a pair-by-pair probability that the pair melts during the evolution, which we relate to the fluctuations of the color charges induced by the interaction of the quarks with the gluon fields. We find that color decorrelation is the main melting mechanism within the pre-equilibrium stage. Moreover, we estimate that within $Δ τ \approx 0.4 - 0.5$ fm/c after the formation time of the pairs, about $50%$ of $c c ˉ$ and $b b ˉ$ pairs are melted.
↳ hep-phnucl-thPRD(2025)·12 citations
08
Numerical study of computational cost of maintaining adiabaticity for long paths
Thomas D. Cohen · Hyunwoo Oh · Veronica Wang
Recent work argued that the scaling of a dimensionless quantity $Q_{D}$ with path length is a better proxy for quantifying the scaling of the computational cost of maintaining adiabaticity than the timescale. It also conjectured that generically the scaling will be superlinear (although special cases exist in which it is linear). The quantity $Q_{D}$ depends only on the properties of ground states along the Hamiltonian path and the rate at which the path is followed. In this paper, we demonstrate that this conjecture holds for simple Hamiltonian systems that can be studied numerically. In particular, the systems studied exhibit the behavior that $Q_{D}$ grows approximately as $L lo g L$ where $L$ is the path length when the threshold error is fixed.
↳ quant-phhep-latnucl-thEPJA(2026)·2 citations
09
An Improved Precision Calculation of the $0 ν β β$ Contact Term within Chiral Effective Field Theory
Graham Van Goffrier🇬🇧
Neutrinoless double-beta ( $0 ν β β$ ) decay is an as-yet unobserved nuclear process, which stands to provide crucial insights for model-building beyond the Standard Model of particle physics. Its detection would simultaneously confirm the hypothesis that neutrinos are Majorana fermions, thus violating lepton-number conservation, and provide the first measurement of the absolute neutrino mass scale. This work aims to improve the estimation within chiral effective field theory of the so-called ''contact term'' for $0 ν β β$ -decay, a short-range two-nucleon effect which is unaccounted for in traditional nuclear approaches to the process. We conduct a thorough review of the justifications for this contact term and the most precise computation of its size to date ( $g_{ν}^{N N}$ = 1.3(6) at renormalisation point $μ = m_{π}$ ), whose precision is limited by a truncation to elastic intermediate hadronic states. We then perform an extension of this analysis to a subleading class of inelastic intermediate states which we characterise, delivering an updated figure for the contact coefficient ( $g_{ν}^{N N}$ = 1.4(3) at $μ = m_{π}$ ) with uncertainty reduced by half. Such ab initio nuclear results, especially with enhanced precision, show promise for the resolution of disagreements between estimates of $0 ν β β$ from different many-body methods.
↳ hep-phnucl-thPRD(2025)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE

On the definition of the nucleon axial charge density

Channels of Stellar-mass Black Hole Formation

Symmetry verification for noisy quantum simulations of non-Abelian lattice gauge theories

Melting of ccˉ and bbˉ pairs in the pre-equilibrium stage of proton-nucleus collisions at the Large Hadron Collider

Numerical study of computational cost of maintaining adiabaticity for long paths

An Improved Precision Calculation of the 0νββ Contact Term within Chiral Effective Field Theory

Affiliations

Melting of $c c ˉ$ and $b b ˉ$ pairs in the pre-equilibrium stage of proton-nucleus collisions at the Large Hadron Collider

An Improved Precision Calculation of the $0 ν β β$ Contact Term within Chiral Effective Field Theory