Thu·Jun 8, 2023Thursday·June 8, 2023

1. 01*

   Dark Matter Constraints from Isomeric ${}^{178m}$Hf

   D. S. M. Alves🇺🇸 · S. R. Elliott🇺🇸 · R. Massarczyk🇺🇸 · S. J. Meijer🇺🇸 · H. Ramani🇺🇸

   We describe a first measurement of the radiation from a ${}^{178m}$Hf sample to search for dark matter. The $\gamma$ flux from this sample, possessed by Los Alamos National Laboratory nuclear chemistry, was measured with a Ge detector at a distance of 4 ft due to its high activity. We search for $\gamma$s that cannot arise from the radioactive decay of ${}^{178m}$Hf, but might arise from the production of a nuclear state due to the inelastic scattering with dark matter. The limits obtained on this $\gamma$ flux are then translated into constraints on the parameter space of inelastic dark matter. Finally, we describe the potential reach of future studies with ${}^{178m}$Hf.

   nucl-exhep-phhep-thPRL(2023)·11 citations
2. 02*

   Binding energies of ground and isomeric states in neutron-rich ruthenium isotopes: measurements at JYFLTRAP and comparison to theory

   M. Hukkanen🇫🇮 · W. Ryssens🇧🇪 · P. Ascher🇫🇷 · M. Bender🇫🇷 · T. Eronen🇫🇮 · S. Grévy🇫🇷 · A. Kankainen🇫🇮 · M. Stryjczyk🇫🇮 · L. Al Ayoubi🇫🇮 · S. Ayet🇩🇪 · O. Beliuskina🇫🇮 · C. Delafosse🇫🇮 and 18 other authors

   We report on precision mass measurements of ${}^{113,115,117}$Ru performed with the JYFLTRAP double Penning trap mass spectrometer at the Accelerator Laboratory of University of Jyväskylä. The phase-imaging ion-cyclotron-resonance technique was used to resolve the ground and isomeric states in ${}^{113,115}$Ru and enabled for the first time a measurement of the isomer excitation energies, $E_x{(}^{113}$Ru${}^m)=100.5(8)$ keV and $E_x{(}^{115}$Ru${}^m)=129(5)$ keV. The ground state of ${}^{117}$Ru was measured using the time-of-flight ion-cyclotron-resonance technique. The new mass-excess value for ${}^{117}$Ru is around 36 keV lower and 7 times more precise than the previous literature value. With the more precise ground-state mass values, the evolution of the two-neutron separation energies is further constrained and a similar trend as predicted by the BSkG1 model is obtained up to the neutron number $N=71$.

   nucl-exnucl-thPRC(2023)·12 citations
3. 03*

   ${\beta }^{-}$ decay $Q$-value measurement of ${}^{136}$Cs and its implications to neutrino studies

   Z. Ge🇫🇮 · T. Eronen🇫🇮 · A. de Roubin🇫🇷 · M. Ramalho🇫🇮 · J. Kostensalo🇫🇮 · J. Kotila🇫🇮 · J. Suhonen🇫🇮 · D. A. Nesterenko🇫🇮 · A. Kankainen🇫🇮 · P. Ascher🇫🇷 · O. Beliuskina🇫🇮 · M. Flayol🇫🇷 and 12 other authors

   The ${\beta }^{-}$ decay $Q$-value of ${}^{136}$Cs ($J^{\pi }=5^{+}$, $t_{1/2}\approx 13$~days) was measured with the JYFLTRAP Penning trap setup at the Ion Guide Isotope Separator On-Line (IGISOL) facility of the University of Jyväskylä, Finland. The mono-isotopic samples required in the measurements were prepared with a new scheme utilised for the cleaning, based on the coupling of dipolar excitation with Ramsey's method of time-separated oscillatory fields and the phase-imaging ion-cyclotron-resonance (PI-ICR) technique. The $Q$ value is determined to be 2536.83(45) keV, which is $\sim$4 times more precise and 11.4(20) keV ($\sim$ 6$\sigma$) smaller than the adopted value in the most recent Atomic Mass Evaluation AME2020. The daughter, ${}^{136}$Ba, has a 4${}^{+}$ state at 2544.481(24) keV and a $3^{-}$ state at 2532.653(23) keV, both of which can potentially be ultralow $Q$-value end-states for the ${}^{136}$Cs decay. With our new ground-to-ground state $Q$ value, the decay energies to these two states become -7.65(45) keV and 4.18(45) keV, respectively. The former is confirmed to be negative at the level of $\sim$ 17$\sigma$, which verifies that this transition is not a suitable candidate for neutrino mass determination. On the other hand, the slightly negative $Q$ value makes this transition an interesting candidate for the study of virtual $\beta$-$\gamma$ transitions. The decay to the 3${}^{-}$ state is validated to have a positive low $Q$ value which makes it a viable candidate for neutrino mass determination. For this transition, we obtained a shell-model-based half-life estimate of $2.1_{-0.8}^{+1.6}\times 10^{12}$ yr.

   nucl-exPRC(2023)·10 citations
4. 04*

   Nuclear mass predictions based on deep neural network and finite-range droplet model (2012)

   To Chung Yiu🇸🇪 · Haozhao Liang🇯🇵 · Jenny Lee🇨🇳

   A neural network with two hidden layers is developed for nuclear mass prediction, based on the finite-range droplet model (FRDM12). Different hyperparameters, including the number of hidden units, the choice of activation functions, the initializers, and the learning rates, are adjusted explicitly and systematically. The resulting mass predictions are achieved by averaging the predictions given by several different sets of hyperparameters with different regularizers and seed numbers. It can provide us not only the average values of mass predictions but also reliable estimations in the mass prediction uncertainties. The overall root-mean-square deviations of nuclear mass have been reduced from $0.603$ MeV for the FRDM12 model to $0.200$ MeV and $0.232$ MeV for the training set and validation set, respectively.

   ↳ nucl-thnucl-exCPC(2024)·5 citations
5. 05*

   Coupled-channel influence on the $a_0(1700/1800)$ line shape

   N. N. Achasov🇷🇺 · G. N. Shestakov🇷🇺

   The current situation with the recently discovered $a_0(1700/1800)$ resonance is very paradoxical: it is believed that $a_0(1700/1800)$ must be strongly coupled with two vector mesons, but there is no direct experimental confirmation of this yet. Based on the assumption that the $a_0(1700/1800)$ is a state similar to the four-quark state from the MIT bag, belonging to either the ${\underline{9}}^{\ast }$ or the ${\underline{36}}^{\ast }$ $q^2{\bar{q}}^2$ multiplet, we analyze the influence of the strong $a_0(1700/1800)$ coupling to the vector channels $K^{\ast }{\bar{K}}^{\ast }$, $\rho \varphi$, and $\rho \omega$ on its line shape in the decay channels into pseudoscalar mesons $K\bar{K}$, $\pi \eta$, and $\pi {\eta }^{\prime }$. This effect depends on the location of the resonance mass $m_{a_0}$ relative to the nominal thresholds of vector channels. For example, if $m_{a_0}\approx 1700$ MeV, then the influence turns out to be hidden in a fairly wide range of coupling constants. On the whole, our analysis shows that, to confirm the presence of the strong $a_0(1700/1800)$ coupling to the vector channels, utterly required is the direct detection of the decays $a_0(1700/1800)\to K^{\ast }{\bar{K}}^{\ast }$, $\rho \varphi$, $\rho \omega$. The appearance of even certain hints at the existence of these decays would make it possible to fundamentally advance in understanding the nature of the new $a_0$ state.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2023)·9 citations
6. 06*

   Exploration of hadronization through heavy flavor production at the future Electron-Ion Collider

   Xuan Li🇺🇸

   The future Electron-Ion Collider (EIC), which is expected to start construction at Brookhaven National Laboratory in 2025, will utilize high-luminosity high-energy electron+proton and electron+nucleus collisions to explore several fundamental questions in the high energy and nuclear physics fields. Exploring how matter is formed from quarks and gluons, which is referred to as the hadronization process, is one of the EIC science objectives. The EIC project detector design led by the ePIC collaboration can realize a series of high precision heavy flavor hadron and jet measurements. Heavy flavor jet substructure and heavy flavor hadrons inside jets, which can provide direct information about the heavy quark hadronization process, have been studied in simulation for electron+proton and electron+nucleus collisions at EIC. The associated physics projections and comparison with latest theoretical calculations will be presented.

   ↳ hep-phhep-exnucl-exnucl-th0 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.