Nuclear Theory·nucl-th

Monday·March 20, 2023

3 papers—1 primary·2 cross-listed

01
[Submitted on 17 Mar 2023]
Momentum dependent nucleon-nucleon contact interaction from a relativistic Lagrangian
E. Filandri🇮🇹 · L. Girlanda🇮🇹
A complete set of parity- and time-reversal conserving relativistic nucleon-nucleon contact operators is identified up to the order $O (p^{4})$ of the expansion in soft momenta $p$ . A basis is also provided for the corresponding non-relativistic operators contributing in the general reference frame. We show that the non-relativistic expansions of the relativistic operators involve twenty-six independent combinations, two starting at $O (p^{0})$ , seven at order $O (p^{2})$ and seventeen at order $O (p^{4})$ . This gives supporting evidence to the existence of two free low-energy constants which parametrize an interaction depending on the total nucleon pair momentum $P$ , and were recently found to be instrumental for the resolution of the long standing $A_{y}$ problem in low-energy $p - d$ scattering. Furthermore, all remaining $P$ -dependent interactions at the same order are uniquely determined as relativistic corrections.
Comments:
Minor changes, added references, to appear in Physics Letters B
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2303.10084 [pdf]
PLB(2023)·6 citations
02
[Submitted on 16 Mar 2023] (cross-list from hep-ph)
Light-front Wave Functions of Vector Mesons in an Algebraic Model
B. Almeida-Zamora🇲🇽 · J.J. Cobos-Martínez🇲🇽 · A. Bashir🇲🇽 · K. Raya🇪🇸 · J. Rodríguez-Quintero🇪🇸 · J. Segovia🇪🇸
Inspired by the recent development of an algebraic model which provides an adequate and unified description of the internal structure of the lowest-lying pseudo-scalar mesons, belonging both to the light quarks sector and to the one of heavy quarks, we perform its first extension to the vector-meson case. The algebraic model describes meson's structure in terms of the spectral density function that appears in a Nakanishi integral representation of the covariant quark-antiquark bound-state amplitude, \emph{i.e.}, the Bethe-Salpeter amplitude. We compute the leading-twist light-front wave functions of the $ρ (770)$ , $ϕ (1020)$ , $J / ψ$ and $Υ (1 S)$ mesons through their connection with the parton distribution amplitudes. Among the results we present, the following are of particular interest: (i) transverse light-front wave functions can be obtained algebraically from the corresponding parton distribution amplitudes, whereas that is not the case for longitudinal light-front wave functions, which requires an intermediate step where a spectral density function must be derived from the particular parton distribution amplitude; (ii) the derived spectral density functions show marked differences between light and heavy vector mesons, the latter being narrower as compared to the former; these are also non-positive definite, although the integral over the entire curve is larger than zero as expected; and (iii) the longitudinal and transverse light-front wave functions of vector mesons with light quark content exhibit steep $x$ - and $p_{⊥}^{2}$ -dependence, while those of the $J / ψ$ and $Υ (1 S)$ mesons are characterized by narrow distributions in the $x$ -range but, comparatively, much more gradual fall-offs with respect to the $p_{⊥}^{2}$ -range depicted.
Comments:
13 pages, 7 figures and 4 tables. Version accepted for publication in Phys. Rev. D
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:
2303.09581 [pdf]
PRD(2023)·14 citations
03
[Submitted on 17 Mar 2023] (cross-list from hep-ph)
Nuclear decay anomalies as a signature of axion dark matter
Xin Zhang🇨🇳 · Nick Houston🇨🇳 · Tianjun Li🇨🇳
A number of nuclear decay anomalies have been reported in the literature, which purport to show periodic variations in the decay rates of certain radioisotopes. If these reports reflect reality, they would necessitate a seismic shift in our understanding of fundamental physics. We provide the first mechanism to explain these findings, via the misalignment mechanism of QCD axion dark matter, wherein oscillations of the effective $θ$ angle induce periodic variation in nuclear binding energies and hence decay rates. As we expect this effect to be most pronounced in low- $Q$ systems, we analyse 12 years of tritium decay data ( $Q ≃$ 18.6 keV) taken at the European Commission's Joint Research Centre. Finding no statistically significant excess, we exclude axion decay constants below $9.4 \times 1 0^{12} - 1.8 \times 1 0^{10}$ GeV (95% confidence level) for masses in the $1.7 \times 10^{- 23} - 8.7 \times 1 0^{- 21}$ eV range.
Comments:
5 pages plus supplementary material. V3: updated to match published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2303.09865 [pdf]
PRD(2023)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE

Momentum dependent nucleon-nucleon contact interaction from a relativistic Lagrangian

Light-front Wave Functions of Vector Mesons in an Algebraic Model

Nuclear decay anomalies as a signature of axion dark matter

Affiliations