Fri·Dec 25, 2020Friday·December 25, 2020

1. 01*

   Lifetime measurements of excited states in ${}^{15}$O

   B. Frentz · A. Aprahamian · A.M. Clark · C. Dulal · J.D. Enright · R.J. deBoer · J. Görres · S.L. Henderson · K.B. Howard · R. Kelmar · K. Lee · L. Morales and 5 other authors

   The CNO cycle is the main energy source in stars more massive than our sun, it defines the energy production and the cycle time that lead to the lifetime of massive stars, and it is an important tool for the determination of the age of globular clusters. One of the largest uncertainties in the CNO chain of reactions comes from the uncertainty in the ${}^{14}$N$(p,\gamma {)}^{15}$O reaction rate. This uncertainty arises predominantly from the uncertainty in the lifetime of the sub-threshold state in ${}^{15}$O at $E_x$ = 6792 keV. Previous measurements of this state's lifetime are significantly discrepant. Here, we report on a new lifetime measurement of this state, as well as the excited states in ${}^{15}$O at $E_x$ = 5181 keV and $E_x$ = 6172 keV, via the ${}^{14}$N$(p,\gamma {)}^{15}$O reaction at proton energies of $E_p=1020$ keV and $E_p=1570$ keV. The lifetimes have been determined with the Doppler-Shift Attenuation Method (DSAM) with three separate, nitrogen-implanted targets with Mo, Ta, and W backing. We obtained lifetimes from the weighted average of the three measurements, allowing us to account for systematic differences between the backing materials. For the 6792 keV state, we obtained a $\tau =0.6\pm 0.4$ fs. To provide cross-validation of our method, we measured the known lifetimes of the states at 5181 keV and 6172 keV to be $\tau =7.5\pm 3.0$ and $\tau =0.7\pm 0.5$ fs, respectively, which are in good agreement with previous measurements.

   nucl-exPRC(2021)·12 citations
2. 02*

   How large is the diffractive contribution to inclusive dijet photoproduction in UPCs at the LHC?

   V. Guzey (St. Petersburg, INP)🇷🇺 · M. Klasen (Munster U., ITP)🇩🇪

   Using next-to-leading order (NLO) perturbative QCD, we calculate the diffractive contribution to inclusive dijet photoproduction in Pb-Pb ultraperipheral collisions (UPCs) at the LHC and find that it does not exceed $5-10$% in small-$x_A$ bins in the ATLAS kinematics at $\sqrt{s_{NN}}=5.02$ TeV. Its smallness is a result of the restricted kinematics ($p_{T1}>20$ GeV and $x_A>0.001$), the large nuclear suppression of nuclear diffractive parton distribution functions predicted in the leading twist model of nuclear shadowing, and additional suppression due to QCD factorization breaking in diffraction. At the same time, using looser $p_T$ cuts, e.g., $p_{T1}>10$ GeV and $p_{Ti\ne 1}>5-7$ GeV, we find that $(d{\sigma }_{\mathrm{diff}}/d{x}_A)/(d{\sigma }_{\mathrm{inc}}/d{x}_A)$ can reach $10-20$% at $x\approx 5\times 10^{-4}$. Also, applying our framework to proton-proton UPCs at $\sqrt{s_{NN}}=13$ TeV, we find that the ratio of the diffractive and inclusive cross sections of dijet photoproduction $(d{\sigma }_{\mathrm{diff}}/d{x}_p)/(d{\sigma }_{\mathrm{inc}}/d{x}_p)$ is as large as $10-15$% for $x_p\sim 5\times 10^{-4}$. An account of the contribution of Pomeron-Pomeron scattering, which is not included in our analysis, should make this ratio somewhat larger.

   ↳ hep-phhep-exnucl-exPRD(2021)·13 citations
3. 03*

   19B isotope as a 17B-n-n three-body cluster close to unitary limit

   J. Carbonell🇫🇷 · E. Hiyama🇯🇵 · R. Lazauskas🇫🇷 · F. M. Marqués🇫🇷

   We describe 19B in terms of a 17B-n-n three-body system, where the two-body subsystems 17B-n and n-n are unbound (virtual) states close to the unitary limit. The energy of 19B ground state is well reproduced and two low-lying resonances are predicted. Their eventual link with the Efimov physics is discussed. This model can be extended to describe the recently discovered resonant states in 20,21B.

   ↳ nucl-thnucl-exJ.Phys.Conf.Ser.(2020)·0 citations
4. 04*

   Bayesian Analysis of a Future Beta Decay Experiment's Sensitivity to Neutrino Mass Scale and Ordering

   A. Ashtari Esfahani🇺🇸 · M. Betancourt🇺🇸 · Z. Bogorad🇺🇸 · S. Böser🇩🇪 · N. Buzinsky🇺🇸 · R. Cervantes🇺🇸 · C. Claessens🇩🇪 · L. de Viveiros🇺🇸 · M. Fertl🇩🇪 · J. A. Formaggio🇺🇸 · L. Gladstone🇺🇸 · M. Grando🇺🇸 and 34 other authors

   Bayesian modeling techniques enable sensitivity analyses that incorporate detailed expectations regarding future experiments. A model-based approach also allows one to evaluate inferences and predicted outcomes, by calibrating (or measuring) the consequences incurred when certain results are reported. We present procedures for calibrating predictions of an experiment's sensitivity to both continuous and discrete parameters. Using these procedures and a new Bayesian model of the $\beta$-decay spectrum, we assess a high-precision $\beta$-decay experiment's sensitivity to the neutrino mass scale and ordering, for one assumed design scenario. We find that such an experiment could measure the electron-weighted neutrino mass within $\sim 40$meV after 1 year (90$\%$ credibility). Neutrino masses $>500$meV could be measured within $\approx 5$meV. Using only $\beta$-decay and external reactor neutrino data, we find that next-generation $\beta$-decay experiments could potentially constrain the mass ordering using a two-neutrino spectral model analysis. By calibrating mass ordering results, we identify reporting criteria that can be tuned to suppress false ordering claims. In some cases, a two-neutrino analysis can reveal that the mass ordering is inverted, an unobtainable result for the traditional one-neutrino analysis approach.

   ↳ physics.data-anhep-phnucl-exPRC(2021)·23 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.