Tue·Jun 23, 2020Tuesday·June 23, 2020

1. 01*

   $K^{+}\Lambda$ photoproduction at forward angles and low momentum transfer

   S. Alef · P. Bauer · D. Bayadilov · R. Beck · A. Bella · J. Bieling · A. Braghieri · P.L. Cole · D. Elsner · R. Di Salvo · A. Fantini · O. Freyermuth and 30 other authors

   $\gamma p\to K^{+}\Lambda$ differential cross sections and recoil polarisation data from threshold for extremely forward angles are presented. The measurements were performed at the BGOOD experiment at ELSA, utilising the high angular and momentum resolution forward spectrometer for charged particle identification. The data discriminates between conflicting results in the world data set and enable extraction of the cross section as the minimum momentum transfer to the recoiling hyperon is approached.

   nucl-exEPJA(2021)·27 citations
2. 02*

   Study of proton capture resonant state of ^{15}O at 7556 keV

   Sathi Sharma🇮🇳 · Arkabrata Gupta🇮🇳 · M. Roy Chowdhury🇮🇳 · A. Mandal🇮🇳 · A. Bisoi🇮🇳 · V. Nanal🇮🇳 · L. C. Tribedi🇮🇳 · M. Saha Sarkar🇮🇳

   The slowest reaction in the CNO cycle 14N(p, gamma)15O has been studied by populating the E^lab_p =278 keV (E^r_c.m.=259 keV) proton capture resonant state of ^{15}O at 7556 keV. The strength of the resonance has been determined from the experimental data. The level lifetime of the sub-threshold resonant state at Ex=6792 keV, as well as the lifetimes of the 5181 keV and 6172 keV states, have been measured using the Doppler shift attenuation method (DSAM). The structural properties of the nucleus ^{15}O, such as, the level energies, transition strengths, level lifetimes, and spectroscopic factors, have been calculated theoretically by using the large basis shell model, which agrees reasonably well with the present as well as the previous experimental data.

   nucl-exnucl-thPRC(2020)·8 citations
3. 03*

   Precision Measurement of the Beam-Normal Single-Spin Asymmetry in Forward-Angle Elastic Electron-Proton Scattering

   QWeak collaboration: D. Androic🇭🇷 · D.S. Armstrong🇺🇸 · A. Asaturyan🇦🇲 · K. Bartlett🇺🇸 · J. Beaufait🇺🇸 · R.S. Beminiwattha🇺🇸 · J. Benesch🇺🇸 · F. Benmokhtar🇺🇸 · J. Birchall🇨🇦 · R.D. Carlini🇺🇸 · J.C. Cornejo🇺🇸 · S. Covrig Dusa🇺🇸 and 82 other authors

   A beam-normal single-spin asymmetry generated in the scattering of transversely polarized electrons from unpolarized nucleons is an observable related to the imaginary part of the two-photon exchange process. We report a 2% precision measurement of the beam-normal single-spin asymmetry in elastic electron-proton scattering with a mean scattering angle of theta_lab = 7.9 degrees and a mean energy of 1.149 GeV. The asymmetry result is B_n = -5.194 +- 0.067 (stat) +- 0.082 (syst) ppm. This is the most precise measurement of this quantity available to date and therefore provides a stringent test of two-photon exchange models at far-forward scattering angles (theta_lab -> 0) where they should be most reliable.

   nucl-exPRL(2020)·12 citations
4. 04*

   Observation of a cusp-like structure in the $\gamma p\to K^{+}{\Sigma }^0$ cross section at forward angles and low momentum transfer

   T.C. Jude · S. Alef · P. Bauer · D. Bayadilov · R. Beck · A. Bella · J. Bieling · A. Braghieri · P.L. Cole · D. Elsner · R. Di Salvo · A. Fantini and 30 other authors

   The $\gamma p\to K^{+}{\Sigma }^0$ differential cross section at extremely forward angles was measured at the BGOOD experiment. A three-quarter drop in strength over a narrow range in energy and a strong dependence on the polar angle of the $K^{+}$ in the centre-of-mass of the reaction is observed at a centre-of-mass energy of 1900\,MeV. Residing close to multiple open and hidden strangeness thresholds, the structure appears consistent with meson-baryon threshold effects which may contribute to the reaction mechanism.

   nucl-exPLB(2021)·24 citations
5. 05*

   Assessing the accuracy of the GENIE event generator with electron-scattering data

   Artur M. Ankowski🇺🇸 · Alexander Friedland🇺🇸

   Precision neutrino oscillation experiments of the future---of which DUNE is a prime example---require reliable event generator tools. The 1--4 GeV energy regime, in which DUNE will operate, is marked by the transition from the low-energy nuclear physics domain to that of perturbative QCD, resulting in rich and highly complex physics. Given this complexity, it is important to establish a validation procedure capable of disentangling the physical processes and testing each of them individually. Here, we demonstrate the utility of this approach by benchmarking the GENIE generator, currently used by all Fermilab-based experiments, against a broad set of inclusive electron-scattering data. This comparison takes advantage of the fact that, while electron-nucleus and neutrino-nucleus processes share a lot of common physics, electron scattering gives one access to precisely known beam energies and scattering kinematics. Exploring the kinematic parameter range relevant to DUNE in this manner, we observe patterns of large discrepancies between the generator and data. These discrepancies are most prominent in the pion-producing regimes and are present not only in medium-sized nuclei, including argon, but also in deuterium and hydrogen targets, indicating mismodeled hadronic physics. Several directions for possible improvement are discussed.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2020)·33 citations
6. 06*

   Excess of soft dielectrons and photons

   I.M. Dremin🇷🇺

   Spectra of unbound electron-positron pairs (dielectrons, in brief) and photons from decays of parapositronia produced in ultraperipheral collisions of electrically charged objects are calculated. Their shapes at energies of the NICA collider are demonstrated. Soft dielectrons and photons are abundantly produced. The relevance of these processes to the astrophysical problem of cooling electron-positron pairs and the intense emission of 511 keV photons from the Galactic center is discussed.

   ↳ hep-phastro-ph.HEhep-exnucl-ex+1Universe(2020)·7 citations
7. 07*

   Selection rules of electromagnetic transitions for chirality-parity violation in atomic nuclei

   Y. Y. Wang🇨🇳 · X. H. Wu🇨🇳 · S. Q. Zhang🇨🇳 · P. W. Zhao🇨🇳 · J. Meng🇨🇳

   The nuclear Chirality-Parity (ChP) violation, a simultaneous breaking of chiral and reflection symmetries in the intrinsic frame, is investigated with a reflection-asymmetric triaxial particle rotor model. A new symmetry for an ideal ChP violation system is found and the corresponding selection rules of the electromagnetic transitions are derived. The fingerprints for the ChP violation including the nearly degenerate quartet bands and the selection rules of the electromagnetic transitions are provided. These fingerprints are examined for ChP quartet bands by taking a two-$j$ shell $h_{11/2}$ and $d_{5/2}$ with typical energy spacing for $A=$ 130 nuclei.

   ↳ nucl-thnucl-exSci.Bull.(2020)·24 citations
8. 08*

   Extracting Hypernuclear Properties from the $(e,e^{\prime }{K}^{+})$ Cross Section

   Omar Benhar🇮🇹

   Experimental studies of hypernuclear dynamics, besides being essential for the understanding of strong interactions in the strange sector, have important astrophysical implications. The observation of neutron stars with masses exceeding two solar masses poses a serious challenge to the models of hyperon dynamics in dense nuclear matter, many of which predict a maximum mass incompatible with the data. In this article, it is argued that valuable new insight may be gained extending the experimental studies of kaon electro production from nuclei to include the $\text{isotope}[208][]\mathrm{Pb}(e,e^{\prime }{K}^{+})\text{isotope}[208][\Lambda ]\mathrm{Tl}$ process. The connection with proton knockout reactions and the availability of accurate $\text{isotope}[208][]\mathrm{Pb}(e,e^{\prime }p)\text{isotope}[207][]\mathrm{Tl}$ data can be exploited to achieve a largely model-independent analysis of the measured cross section. A framework for the description of kaon electro production based on the formalism of nuclear many-body theory is outlined.

   ↳ nucl-thnucl-exParticles(2021)·0 citations
9. 09*

   Light nuclei production in Au + Au collisions at $\sqrt{s_{NN}}$ = 7.7-80 GeV from UrQMD model

   X. G. Deng🇨🇳 · Y. G. Ma🇨🇳

   Light nuclei production in relativistic ${}^{197}$Au + ${}^{197}$Au collisions from 7.7 to 80 GeV is investigated within the Ultra-relativistic-Quantum-Molecular-Dynamics model (UrQMD) with a naive coalescence approach. The results of the production of light nuclei at midrapidity can essentially match up the experimental data and a slight enhancement of combined ratio of $N_p{N}_t/N_d^2$ where $N_p,N_d$ and $N_t$ represent respectively the yields of proton, deuteron and triton, which is sensitive to the neutron density fluctuations, occurs around 20 GeV. However, this enhanced $N_p{N}_t/N_d^2$ ratio should not be over-understood considering that the present UrQMD model is a cascade version without equation of state (EoS), i.e. there is an absence of critical end point mechanism. Furthermore, within different rapidity regions, the kinetic temperatures of different light nuclei are extracted by the Blast-wave model analysis and ratios among different light nuclei are also discussed.

   ↳ nucl-thhep-phnucl-exPLB(2020)·22 citations
10. 10*

    Spin Hall effect in heavy ion collisions

    Shuai Y.F. Liu🇨🇳 · Yi Yin🇨🇳

    Spin Hall effect (SHE) is the generation of spin current due to an electric field, and has been observed in a variety of materials. The analogous spin Hall current can be induced by chemical potential and temperature gradient, both of which are present in hot and dense nuclear matter created in heavy-ion collisions. In this letter, we investigate the perspective of detecting spin Hall current experimentally. We propose to measure "directed spin flow", the first Fourier coefficients of local spin polarization of $\Lambda$ ($\bar{\Lambda }$) hyperon, at central collisions to probe spin Hall current. To quantify induced spin current, we evaluate relevant transport coefficients using thermal field theory. We benchmark the magnitude of the induced "directed spin flow" at two representatively collisions energies, namely ${\sqrt{s}}_{NN}=200\mathrm{GeV}$ and ${\sqrt{s}}_{NN}=19.6\mathrm{GeV}$, by employing a phenomenologically motivated freeze-out prescription. At both beam energies, the resulting "directed spin flow" ranges from $10^{-4}$ to $10^{-3}$, and is very sensitive to the rapidity.

    ↳ nucl-thhep-phnucl-exPRD(2021)·95 citations
11. 11*

    Variation of Single-Particle Energies: Scaling Behavior for the Spectrum of ${}^{48}$Cr

    Castaly Fan · Praveen C. Srivastava🇮🇳 · Larry Zamick🇺🇸

    We perform shell model calculations for ${}^{48}$Cr using GXPF1A and FPD6 interactions by varying single particle energies. We find a scaling behavior which leads to the finding that many different sets of interactions with vastly different single particle energies can give almost identical results for the yrast spectrum of ${}^{48}$Cr

    ↳ nucl-thnucl-ex0 citations
12. 12*

    Charm jets as a probe for strangeness at the future Electron-Ion Collider

    Miguel Arratia🇺🇸 · Yulia Furletova🇺🇸 · T. J. Hobbs🇺🇸 · Fredrick Olness🇺🇸 · Stephen J. Sekula🇺🇸

    We explore the feasibility of the measurement of charm-jet cross sections in charged-current deep-inelastic scattering at the future Electron-Ion Collider. This channel provides clean sensitivity to the strangeness content of the nucleon in the high-$x$ region. We estimate charm-jet tagging performance with parametrized detector simulations. We show the expected sensitivity to various scenarios for strange parton distribution functions. We argue that this measurement will be key to future QCD global analyses, so it should inform EIC detector designs and luminosity requirements.

    ↳ hep-phhep-exnucl-exnucl-thPRD(2021)·44 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.