Mon·Mar 20, 2023Monday·March 20, 2023

1. 01*

   Compilation of isomeric ratios of light particle induced nuclear reactions

   A. Rodrigo · N. Otuka · S. Takács🇭🇺 · A.J. Koning🇦🇹

   Experimental isomeric ratios of light (A$\le$4) particle-induced nuclear reactions were compiled for the product nuclides having metastable states with half-lives longer than 0.1 sec. The experimental isomeric ratio data were taken from the EXFOR library and reviewed. When an experiment reports isomer production cross sections instead of isomeric ratios, the cross sections taken from the EXFOR library were converted to the isomeric ratios by us. During compilation, questionable data (e.g.,preliminary data compiled in EXFOR in parallel with their final data, sum of isomer production cross sections larger than the total production cross sections) were excluded. As an application of the new compilation, goodness-of-fit was studied for the isomeric ratios predicted by the reaction model code TALYS-1.96.

   nucl-exNucl.Data Tabl.(2023)·9 citations
2. 02*

   Angular correlation of the two gamma rays produced in the thermal neutron capture on gadolinium-155 and gadolinium-157

   Pierre Goux🇯🇵 · Franz Glessgen🇯🇵 · Enrico Gazzola🇯🇵 · Mandeep Singh Reen🇯🇵 · William Focillon🇫🇷 · Michel Gonin🇫🇷 · Tomoyuki Tanaka🇯🇵 · Kaito Hagiwara🇯🇵 · Ajmi Ali🇯🇵 · Takashi Sudo🇯🇵 · Yusuke Koshio🇯🇵 · Makoto Sakuda🇯🇵 and 6 other authors

   The ANNRI-Gd collaboration studied in detail the single $\gamma$-ray spectrum produced from the thermal neutron capture on ${}^{155}$Gd and ${}^{157}$Gd in our previous publications. Gadolinium targets were exposed to a neutron beam provided by the Japan Spallation Neutron Source (JSNS) in J-PARC, Japan. In the present analysis, one new additional coaxial germanium crystal was used in the analysis in combination with the fourteen germanium crystals in the cluster detectors to study the angular correlation of the two $\gamma$ rays emitted in the same neutron capture. We present for the first time angular correlation functions for two $\gamma$ rays produced during the electromagnetic cascade transitions in the (n, $\gamma$) reactions on ${}^{155}$Gd and ${}^{157}$Gd. As expected, we observe the mild angular correlations for the strong, but rare transitions from the resonance state to the two energy levels of known spin-parities. Contrariwise, we observe negligibly small angular correlations for arbitrary pairs of two $\gamma$ rays produced in the majority of cascade transitions from the resonance state to the dense continuum states.

   nucl-exphysics.ins-detPTEP(2023)·0 citations
3. 03*

   Comparison of inclusive and photon-tagged jet suppression in 5.02 TeV Pb+Pb collisions with ATLAS

   ATLAS Collaboration

   Parton energy loss in the quark-gluon plasma (QGP) is studied with a measurement of photon-tagged jet production in 1.7 nb${}^{-1}$ of Pb+Pb data and 260 pb${}^{-1}$ of $pp$ data, both at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV, with the ATLAS detector. The process $pp\to \gamma$+jet+$X$ and its analogue in Pb+Pb collisions is measured in events containing an isolated photon with transverse momentum ($p_{\mathrm{T}}$) above $50$ GeV and reported as a function of jet $p_{\mathrm{T}}$. This selection results in a sample of jets with a steeply falling $p_{\mathrm{T}}$ distribution that are mostly initiated by the showering of quarks. The $pp$ and Pb+Pb measurements are used to report the nuclear modification factor, $R_{\mathrm{AA}}$, and the fractional energy loss, $S_{\mathrm{loss}}$, for photon-tagged jets. In addition, the results are compared with the analogous ones for inclusive jets, which have a significantly smaller quark-initiated fraction. The $R_{\mathrm{AA}}$ and $S_{\mathrm{loss}}$ values are found to be significantly different between those for photon-tagged jets and inclusive jets, demonstrating that energy loss in the QGP is sensitive to the colour-charge of the initiating parton. The results are also compared with a variety of theoretical models of colour-charge-dependent energy loss.

   nucl-exhep-exPLB(2023)·51 citations
4. 04*

   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 $\rho (770)$, $\varphi (1020)$, $J/\psi$ and ${\rm Y}(1S)$ 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 $p_{\perp }^2$-dependence, while those of the $J/\psi$ and ${\rm Y}(1S)$ mesons are characterized by narrow distributions in the $x$-range but, comparatively, much more gradual fall-offs with respect to the $p_{\perp }^2$-range depicted.

   ↳ hep-phhep-exhep-latnucl-ex+1PRD(2023)·14 citations
5. 05*

   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 $\theta$ 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 ($Q\simeq$ 18.6 keV) taken at the European Commission's Joint Research Centre. Finding no statistically significant excess, we exclude axion decay constants below $9.4\times 10^{12}-1.8\times 10^{10}$ GeV (95% confidence level) for masses in the $1.7\times {10}^{-23}-8.7\times 10^{-21}$ eV range.

   ↳ hep-phnucl-exnucl-thPRD(2023)·19 citations
6. 06*

   Expanding RIB Capabilities at the Cyclotron Institute: \textsuperscript{3}He-LIG production with an Isobar Separator LSTAR

   D. Melconian🇺🇸 · G.P.A. Berg🇺🇸 · P.D. Shidling · M. Couder🇺🇸 · M. Brodeur🇺🇸 · G. Chubarian · V.E. Iacob · J. Klimo · G. Tabacaru

   A new \textsuperscript{3}He-driven IGISOL production station and mass separator have been designed to produce neutron-deficient low-mass isotopes at the Cyclotron Institute for the TAMUTRAP facility. The LSTAR design has a mass resolution $M/\Delta M\ge 3,000$ to reject contaminants with $>95\%$ efficiency.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.B(2023)·2 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.