Nuclear Theory·nucl-th

Friday·February 11, 2022

16 papers—7 primary·9 cross-listed

08
[Submitted on 9 Feb 2022] (cross-list from hep-th)
Deconfinement and Error Thresholds in Holography
Ning Bao🇺🇸 · ChunJun Cao🇺🇸 · Guanyu Zhu🇺🇸
We study the error threshold properties of holographic quantum error-correcting codes. We demonstrate that holographic CFTs admit an algebraic threshold, which is related to the confinement-deconfinement phase transition. We then apply geometric intuition from holography and the Hawking-Page phase transition to motivate the CFT result, and comment on potential extensions to other confining theories.
Comments:
6 pages, 3 figures. Updated to match published version
Subjects:
High Energy Physics — Theory (hep-th); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2202.04710 [pdf]
PRD(2022)·11 citations
09
[Submitted on 10 Feb 2022] (cross-list from nucl-ex)
Coherent photoproduction of the neutral pion and eta meson on the deuteron at incident energies below 1.15 GeV
T. Ishikawa🇯🇵 · A. Fix🇷🇺 · H. Fujimura🇯🇵 · H. Fukasawa🇯🇵 · R. Hashimoto🇯🇵 · Q. He🇯🇵 · Y. Honda🇯🇵 · T. Iwata🇯🇵 · S. Kaida🇯🇵 · J. Kasagi🇯🇵 · A. Kawano · S. Kuwasaki🇯🇵 and 26 other authors
Coherent photoproduction of the neutral pion and eta meson on the deuteron, $γ d$ { $\to$ } $π^{0} η d$ , has been experimentally studied at incident photon energies ranging from the reaction threshold to 1.15 GeV. The total cross section demonstrates a rapid rise below 1 GeV. The data are underestimated by the existing theoretical calculations based on quasi-free $π^{0} η$ photoproduction on the nucleon followed by deuteron coalescence. At the same time, the data are rather well reproduced by the calculations taking into account the final-state interaction. We have also measured for the first time the differential cross sections: the $π^{0} η$ invariant-mass distribution $d σ / d M_{π η}$ , the $π^{0} d$ invariant-mass distribution $d σ / d M_{π d}$ , the $η d$ invariant-mass distribution $d σ / d M_{η d}$ , and the distribution over the deuteron emission angle $d σ / d Ω_{d}$ in the overall center-of-mass frame. The measured cross section $d σ / d Ω_{d}$ does not exhibit strongly backward-peaking behavior predicted by the calculations. At all incident energies, an increase in $d σ / d M_{η d}$ near the $η d$ threshold is observed, which indicates a bound or virtual $η d$ state resulting from a strong attraction between $η$ and a deuteron. The possibilities of using coherent $π^{0} η$ photoproduction on a nucleus to study the $η$ -nuclear interaction are also discussed.
Comments:
15 pages, 9 figures
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2202.04776 [pdf]
PRC(2022)·12 citations
10
[Submitted on 10 Feb 2022] (cross-list from hep-ph)
$Λ_{b} \to p$ transition form factors in perturbative QCD
Jia-Jie Han🇨🇳 · Ya Li🇨🇳 · Hsiang-nan Li🇹🇼 · Yue-Long Shen🇨🇳 · Zhen-Jun Xiao🇨🇳 · Fu-Sheng Yu🇨🇳
We reanalyze the $Λ_{b} \to p$ transition form factors in the perturbative QCD (PQCD) approach by including higher-twist light-cone distribution amplitudes (LCDAs) of a $Λ_{b}$ baryon and a proton. The previous PQCD evaluation performed decades ago with only the leading-twist $Λ_{b}$ baryon and proton LCDAs gave the form factors, which are two orders of magnitude smaller than indicated by experimental data. We find that the twist-4 $Λ_{b}$ baryon LCDAs and the twist-4 and -5 proton LCDAs contribute dominantly, and the enhanced form factors become consistent with those from lattice QCD and other nonperturbative methods. The estimated branching ratios of the semileptonic decays $Λ_{b} \to p ℓ ν ˉ_{ℓ}$ and the hadronic decay $Λ_{b} \to p π$ are also close to the data. It implies that the $b$ quark mass is not really heavy enough, and higher-power contributions play a crucial role, similar to the observation made in analyses of $B$ meson transition form factors. With the formalism established in this work, we are ready to study various exclusive heavy baryon decays systematically in the PQCD approach.
Comments:
37 pages, 7 figures, version to be published in Eur.Phys.J.C
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2202.04804 [pdf]
EPJC(2022)·38 citations
11
[Submitted on 10 Feb 2022] (cross-list from hep-ph)
New-physics signatures via $C P$ violation in $η^{(')} \to π^{0} μ^{+} μ^{-}$ and $η^{'} \to η μ^{+} μ^{-}$ decays
Rafel Escribano🇪🇸 · Emilio Royo🇪🇸 · Pablo Sanchez-Puertas🇪🇸
In this work we investigate the prospect of observing new-physics signatures via $C P$ violation in $η^{(')} \to π^{0} μ^{+} μ^{-}$ and $η^{'} \to η μ^{+} μ^{-}$ decays at the REDTOP experiment. We make use of the SMEFT to parametrise the new-physics $C P$ -violating effects and find that the projected REDTOP statistics are not competitive with respect to nEDM experiments. This reasserts the $η \to μ^{+} μ^{-}$ process as the most promising channel to find $C P$ -violation at this experimental facility.
Comments:
12 pages, 1 figure, 1 table; v2 includes a comment about the neutron EDM constraint and possible accidental Wilson coefficient cancellations
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2202.04886 [pdf]
JHEP(2022)·14 citations
12
[Submitted on 10 Feb 2022] (cross-list from quant-ph)
Random-Matrix Approach to Transition-State Theory
H. A. Weidenmüller🇩🇪
To model a complex system intrinsically separated by a barrier, we use two random Hamiltonians, coupled to each other either by a tunneling matrix element or by an intermediate transition state. We study that model in the universal limit of large matrix dimension. We calculate the average probability for transition from scattering channel coupled to the first Hamiltonian to a scattering channel coupled to the second Hamiltonian. Using only the assumption that the sum of transmission coefficients of channels coupled to the second Hamiltonian is large we retrieve transition-state theory in its general form. For tunneling through a very thick barrier independence of formation and decay of the tunneling process hold more generally.
Comments:
6 pages no figures
Subjects:
Quantum Physics (quant-ph); Nuclear Theory (nucl-th)
arXiv:
2202.04914 [pdf]
PRE(2022)·6 citations
13
[Submitted on 10 Feb 2022] (cross-list from hep-ph)
QCD axial anomaly enhances the $η η^{'}$ decay of the hybrid candidate $η_{1} (1855)$
Hua-Xing Chen🇨🇳 · Niu Su🇨🇳 · Shi-Lin Zhu🇨🇳
We study the hybrid mesons with the exotic quantum number $I^{G} J^{P C} = 0^{+} 1^{-+}$ and investigate their decays into the $η η^{'}$ , $a_{1} (1260) π$ , $f_{1} (1285) η$ , $f_{1} (1420) η$ , $K^{*} (892) K ˉ$ , $K_{1} (1270) K ˉ$ , and $K_{1} (1400) K ˉ$ channels. We find that the QCD axial anomaly enhances the decay width of the $η η^{'}$ channel although this mode is strongly suppressed by the small $P$ -wave phase space. Our results support the interpretation of the $η_{1} (1855)$ recently observed by BESIII as the $s ˉ s g$ hybrid meson of $I^{G} J^{P C} = 0^{+} 1^{-+}$ . The QCD axial anomaly ensures the $η η^{'}$ decay mode to be a characteristic signal of the hybrid nature of the $η_{1} (1855)$ .
Comments:
8 pages, 2 figures, 1 table, references added, to be published in Chin. Phys. Lett
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:
2202.04918 [pdf]
Chin.Phys.Lett.(2022)·55 citations
14
[Submitted on 10 Feb 2022] (cross-list from nucl-ex)
Light Baryon Spectroscopy
Annika Thiel🇩🇪 · Farah Afzal🇩🇪 · Yannick Wunderlich🇩🇪
This review treats the advances in Light Baryon Spectroscopy of the last two decades, which were mainly obtained by measuring meson-production reactions at photon facilities all over the world. We provide a consistent compendium of experimental results, as well as a review of the theoretical methods of amplitude analysis used to analyze the data. The most significant datasets are presented in detail and are listed in combination with a full set of the relevant references. In addition, a brief summary of spin-formalisms, which are ubiquitous in Light Baryon Spectroscopy, as well as a review on complete experiments, are provided. The synthesis of the reviewed knowledge is presented in a full interpretation of the new results on the Light Baryon Spectrum.
Comments:
142 pages, 52 figures, 19 tables; Version 1 has been accepted for publication in "Progress in Particle and Nuclear Physics"; Version 2 contains further detail improvements
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2202.05055 [pdf]
PPNP(2022)·84 citations
15
[Submitted on 10 Feb 2022] (cross-list from nucl-ex)
Beta decay of halo nuclei
Karsten Riisager
Beta decay is a well-established and efficient probe of nuclear structure and provides important information also for halo nuclei. Detailed decay studies of near-dripline nuclei are challenging, but are now feasible due to the technical progress during the last decades in isotope production as well as detection capabilities. The halo structure can change the dynamics of the decay process, most noticably when decays proceed directly to continuum states as seems to be the case in beta-delayed deuteron emission, a process only observed until now for the halo nuclei $^{6}$ He and $^{11}$ Li. The pronounced clustering in halo states also leaves an imprint on the decay patterns, although the isospin symmetry remains important; in several cases the isobaric analogue states of halo states have also been established. Beta-delayed particle emission channels can be expected to dominate the decays of heavier halo nuclei, if not in terms of branching ratio than certainly in terms of beta strength. A remaining challenge is to find experimental as well as theoretical tools to study the multi-neutron final states that appear for most neutron dripline nuclei.
Comments:
22 pages, 5 figures. Contribution to the "Handbook of Nuclear Physics", Springer, 2022, edited by I. Tanihata, H. Toki and T. Kajino
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2202.05075 [pdf]
1 citation
16
[Submitted on 10 Feb 2022] (cross-list from hep-ph)
Dimensional reduction and the generalized pion in a magnetic field within the NJL model
Jingyi Chao🇨🇳 · Yu-Xin Liu🇨🇳
In this work, the mass of the neutral pion is investigated in the presence of background magnetic fields in the framework of the Nambu--Jona-Lasinio model. Taking into account the anisotropic four-fermion interactions, a tensor current arises in the magnetized QCD system, which forms an anomalous magnetic moment (AMM) coupling in the Dirac equation for the quarks. By solving the gap equations, we find that the sign of the dynamically generated AMM is opposite to the sign of the quark's charge and its magnitude is definitely smaller than the constituent mass. We construct two generalized Nambu-Goldstone pions, which emerge as combinations of the quantum fluctuations around the conventional scalar and the emergent tensor chiral condensates. We analytically demonstrate that the Goldstone nature has been spoiled by the dimensional reduction in the two-particle state and the corresponding decreasing mass of the lighter generalized pionic mode is a remnant of the infrared dynamics.
Comments:
12 pages, 1 figure, journal accepted version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2202.05090 [pdf]
PRD(2023)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE