Tue·Apr 23, 2019Tuesday·April 23, 2019

1. 01*

   Updated Summation Model: An Improved Agreement with the Daya Bay Antineutrino Fluxes

   M. Estienne (1) · M. Fallot (1) · A. Algora (2 and 3) · J. Briz-Monago (1) · V.M. Bui (1) · S. Cormon (1) · W. Gelletly (4) · L. Giot (1) · V. Guadilla (1) · D. Jordan (2) · L. Le Meur (1) · A. Porta (1) and 20 other authors

   A new summation method model of the reactor antineutrino energy spectrum is presented. It is updated with the most recent evaluated decay databases and with our Total Absorption Gamma-ray Spectroscopy measurements performed during the last decade. For the first time the spectral measurements from the Daya Bay experiment are compared with the detected antineutrino energy spectrum computed with the updated summation method without any renormalisation. The results exhibit a better agreement than is obtained with the Huber-Mueller model in the 2 to 5 MeV range, the region which dominates the detected flux. An unexpected systematic trend is found that the detected antineutrino flux computed with the summation model decreases with the inclusion of more Pandemonium free data. The detected flux obtained now lies only 1.9% above that detected in the Daya Bay experiment, a value that may be reduced with forthcoming new Pandemonium free data leaving less and less room to the reactor anomaly. Eventually, the new predictions of individual antineutrino spectra for the ${}^{235}$U, ${}^{239}$Pu, ${}^{241}$Pu and ${}^{238}$U are used to compute the dependence of the reactor antineutrino spectral shape on the fission fractions.

   nucl-exPRL(2019)·163 citations
2. 02*

   Novel Techniques for Constraining Neutron-Capture Rates Relevant for r-Process Heavy-Element Nucleosynthesis

   A. C. Larsen🇳🇴 · A. Spyrou🇺🇸 · S.N. Liddick🇺🇸 · M. Guttormsen🇳🇴

   The rapid-neutron capture process ($r$ process) is identified as the producer of about 50\% of elements heavier than iron. This process requires an astrophysical environment with an extremely high neutron flux over a short amount of time ($\sim$ seconds), creating very neutron-rich nuclei that are subsequently transformed to stable nuclei via ${\beta }^{-}$ decay. One key ingredient to large-scale $r$-process reaction networks is radiative neutron-capture ($n,\gamma$) rates, for which there exist virtually no data for extremely neutron-rich nuclei involved in the $r$ process. Due to the current status of nuclear-reaction theory and our poor understanding of basic nuclear properties such as level densities and average $\gamma$-decay strengths, theoretically estimated ($n,\gamma$) rates may vary by orders of magnitude and represent a major source of uncertainty in any nuclear-reaction network calculation of $r$-process abundances. In this review, we discuss new approaches to provide information on neutron-capture cross sections and reaction rates relevant to the $r$ process. In particular, we focus on indirect, experimental techniques to measure radiative neutron-capture rates. While direct measurements are not available at present, but could possibly be realized in the future, the indirect approaches present a first step towards constraining neutron-capture rates of importance to the $r$ process.

   nucl-exastro-ph.HEastro-ph.SRPPNP(2019)·73 citations
3. 03*

   High-stability, high-voltage power supplies for use with multi-reflection time-of-flight mass spectrographs

   P. Schury · M. Wada · H. Wollnik J-Y. Moon · T. Hashimoto · M. Rosenbusch

   Achieving the highest possible mass resolving power in a multi-reflection time-of-flight mass spectrometer requires very high-stability power supplies. To this end, we have developed a programmable high-voltage power supply that can achieve long-term stability on the order of parts-per-million. Herein we present the design of the stable high-voltage system and bench-top stability measurements up to 1~kV; the stabilization technique can, in principle, be applied up to 15~kV or more.. We demonstrate that in the $\le$1~Hz band the output stability is on the level of 1~part per million (ppm) during one hour, with only slightly more output variation across 3 days. We further demonstrate that the output is largely free of noise in the 1~Hz -- 200~Hz band. We also demonstrate settling to the ppm level within one minute following a 100~V step transition. Finally, we demonstrate that when these power supplies are used to bias the electrodes of a multi-reflection time-of-flight mass spectrograph the measured time-of-flight is stable on the ppm-level for at least one hour.

   ↳ physics.ins-detnucl-exRev.Sci.Instrum.(2020)·6 citations
4. 04*

   Nuclear matter properties at finite temperatures from effective interactions

   Jun Xu🇨🇳 · Arianna Carbone🇩🇪 · Zhen Zhang🇨🇳 · Che Ming Ko🇺🇸

   We study if commonly used nucleon-nucleon effective interactions, obtained from fitting the properties of cold nuclear matter and of finite nuclei, can properly describe the hot dense nuclear matter produced in intermediate-energy heavy-ion collisions. We use two representative effective interactions, i.e., an improved isospin- and momentum-dependent interaction with its isovector part calibrated by the results from the \emph{ab initio} non-perturbative self-consistent Green's function (SCGF) approach with chiral forces, and a Skyme-type interaction fitted to the equation of state of cold nuclear matter from chiral effective many-body perturbation theory and the binding energy of finite nuclei. In the mean-field approximation, we evaluate the equation of state and the single-nucleon potential for nuclear matter at finite temperatures and compare them to those from the SCGF approach. We find that the improved isospin- and momentum-dependent interaction reproduces reasonably well the SCGF results due to its weaker momentum dependence of the mean-field potential than in the Skyrme-type interaction. Our study thus indicates that effective interactions with the correct momentum dependence of the mean-filed potential can properly describe the properties of hot dense nuclear matter and are thus suitable for use in transport models to study heavy-ion collisions at intermediate energies.

   ↳ nucl-thnucl-exPRC(2019)·17 citations
5. 05*

   The Role of Lattice QCD in Searches for Violations of Fundamental Symmetries and Signals for New Physics

   Vincenzo Cirigliano🇺🇸 · Zohreh Davoudi🇺🇸 · Tanmoy Bhattacharya🇺🇸 · Taku Izubuchi🇺🇸 · Phiala E. Shanahan🇺🇸 · Sergey Syritsyn🇺🇸 · Michael L. Wagman🇺🇸

   This document is one of a series of whitepapers from the USQCD collaboration. Here, we discuss opportunities for Lattice Quantum Chromodynamics (LQCD) in the research frontier in fundamental symmetries and signals for new physics. LQCD, in synergy with effective field theories and nuclear many-body studies, provides theoretical support to ongoing and planned experimental programs in searches for electric dipole moments of the nucleon, nuclei and atoms, decay of the proton, $n$-$\overline{n}$ oscillations, neutrinoless double-$\beta$ decay of a nucleus, conversion of muon to electron, precision measurements of weak decays of the nucleon and of nuclei, precision isotope-shift spectroscopy, as well as direct dark matter detection experiments using nuclear targets. This whitepaper details the objectives of the LQCD program in the area of Fundamental Symmetries within the USQCD collaboration, identifies priorities that can be addressed within the next five years, and elaborates on the areas that will likely demand a high degree of innovation in both numerical and analytical frontiers of the LQCD research.

   ↳ hep-lathep-exhep-phnucl-ex+1EPJA(2019)·66 citations
6. 06*

   Status and Future Perspectives for Lattice Gauge Theory Calculations to the Exascale and Beyond

   Bálint Joó🇺🇸 · Chulwoo Jung🇺🇸 · Norman H. Christ🇺🇸 · William Detmold🇺🇸 · Robert G. Edwards🇺🇸 · Martin Savage🇺🇸 · Phiala Shanahan🇺🇸

   In this and a set of companion whitepapers, the USQCD Collaboration lays out a program of science and computing for lattice gauge theory. These whitepapers describe how calculation using lattice QCD (and other gauge theories) can aid the interpretation of ongoing and upcoming experiments in particle and nuclear physics, as well as inspire new ones.

   ↳ hep-lathep-exnucl-exphysics.comp-phEPJA(2019)·70 citations
7. 07*

   Structure of the nucleon and its first radial excitation

   Jorge Segovia🇪🇸

   A Poincaré-covariant continuum approach to the three valence-quark bound-state problem in quantum field theory is used to perform a detailed analysis of the nucleon's ground and first excited states: the so-called $N(940){\frac{1}{2}}^{+}$ and $N(1440){\frac{1}{2}}^{+}$. Such analysis predicts the presence of nonpointlike, fully-interacting quark-quark (diquark) correlations within them, being the isoscalar-scalar and isovector-pseudovector diquarks overwhelmingly dominant with similar relative strengths in both states. Moreover, the rest-frame wave functions of both states are largely $S$-wave in nature and the first excited state in this $1/2^{+}$ channel has the appearance of a radial excitation of the ground state. All these features have numerous observable consequences, we show herein those related with the nucleon's elastic, Roper's elastic and nucleon-to-Roper transition electromagnetic form factors, for both charged and neutral channels.

   ↳ nucl-thhep-exhep-lathep-ph+1Few Body Syst.(2019)·5 citations
8. 08*

   Nuclear gluons at RHIC in a multi-observable approach

   Ilkka Helenius🇫🇮 · John Lajoie🇺🇸 · Joseph D. Osborn🇺🇸 · Petja Paakkinen🇫🇮 · Hannu Paukkunen🇫🇮

   We explore the possibility of measuring nuclear gluon distributions at the Relativistic Heavy-Ion Collider (RHIC) with $\sqrt{s}=200\mathrm{GeV}$ proton-nucleus collisions. In addition to measurements at central rapidity, we consider also observables at forward rapidity, consistent with proposed upgrades to the experimental capabilities of STAR and sPHENIX. The processes we consider consist of Drell-Yan dilepton, dijet, and direct photon-jet production. The Drell-Yan process is found to be an efficient probe of gluons at small momentum fractions. In order to fully utilize the potential of Drell-Yan measurements we demonstrate how the overall normalization uncertainty present in the experimental data can be fixed using other experimental observables. An asset of the RHIC collider is its flexibility to run with different ion beams, and we outline how this ability could be taken advantage of to measure the $A$ dependence of gluon distributions for which the current constraints are scarce.

   ↳ hep-phhep-exnucl-exPRD(2019)·7 citations
9. 09*

   Lattice QCD and Neutrino-Nucleus Scattering

   Andreas S. Kronfeld🇺🇸 · David G. Richards🇺🇸 · William Detmold🇺🇸 · Rajan Gupta🇺🇸 · Huey-Wen Lin🇺🇸 · Keh-Fei Liu🇺🇸 · Aaron S. Meyer🇺🇸 · Raza Sufian🇺🇸 · Sergey Syritsin🇺🇸

   This document is one of a series of whitepapers from the USQCD collaboration. Here, we discuss opportunities for lattice QCD in neutrino-oscillation physics, which inevitably entails nucleon and nuclear structure. In addition to discussing pertinent lattice-QCD calculations of nucleon and nuclear matrix elements, the interplay with models of nuclei is discussed. This program of lattice- QCD calculations is relevant to current and upcoming neutrino experiments, becoming increasingly important on the timescale of LBNF/DUNE and HyperK.

   ↳ hep-lathep-exhep-phnucl-ex+1EPJA(2019)·94 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.