Fri·Apr 1, 2022Friday·April 1, 2022

1. 01*

   Exclusive ${\pi }^{-}$ Electroproduction off the Neutron in Deuterium in the Resonance Region

   Y. Tian🇺🇸 · R. W. Gothe🇺🇸 · V. I. Mokeev🇺🇸 · G. Hollis🇺🇸 · M. J. Amaryan🇺🇸 · W. R. Armstrong🇺🇸 · H. Atac🇺🇸 · H. Avakian🇺🇸 · L. Barion🇮🇹 · M. Battaglieri🇮🇹 · I. Bedlinskiy🇷🇺 · B. Benkel🇨🇱 and 131 other authors

   New results for the exclusive and quasi-free cross sections off neutrons bound in deuterium ${\gamma }_{v}n(p)\to p{\pi }^{-}(p)$ are presented over a wide final state hadron angle range with a kinematic coverage of the invariant mass ($W$) up to 1.825 GeV and the virtual photon four-momentum transfer squared ($Q^2$) from 0.4 to 1.0 GeV${}^2$. The exclusive structure functions were extracted and their Legendre moments were obtained. Final-state-interaction contributions have been kinematically separated from the extracted quasi-free cross sections off bound neutrons solely based on the analysis of the experimental data. These new results will serve as long-awaited input for phenomenological analyses to extract the $Q^2$ evolution of previously unavailable $n\to N^{\ast }$ electroexcitation amplitudes and to improve state-of-the-art models of neutrino scattering off nuclei by augmenting the already available results from free protons.

   nucl-exPRC(2023)·4 citations
2. 02*

   Influence of the recoil-order and radiative correction on the beta decay correlation coefficients in mirror decays

   S. Vanlangendonck🇧🇪 · N. Severijns🇧🇪 · L. Hayen🇺🇸 · F. Glück🇩🇪

   Measurements of the beta decay correlation coefficients in nuclear decay aim for a precision below $1\%$ and theoretical predictions should follow this trend. In this work, the influence of the two dominant Standard Model correction terms, i.e. the recoil-order and the radiative correction, are studied for the most commonly measured beta correlations, i.e. the $\beta$-asymmetry parameter ($A_{\beta }$) and the $\beta -\nu$ angular correlation ($a_{\beta \nu }$). The recoil-order correction is calculated with the well-known Holstein formalism using the impulse approximation to evaluate experimentally inaccessible form factors. For the $\beta -\nu$ angular correlation previously unpublished, semi-analytical radiative correction values are tabulated. Results are presented for the mirror beta decays up to $A=45$. We examine the effect of both corrections and provide a comparison between different isotopes. This comparison will help planning, analysing, and comparing future experimental efforts.

   nucl-exPRC(2022)·6 citations
3. 03*

   Charm- and Bottom-Quark Production in Au$+$Au Collisions at $\sqrt{s_{{}_{NN}}}$ = 200 GeV

   PHENIX Collaboration: N.J. Abdulameer · U. Acharya · A. Adare · C. Aidala · N.N. Ajitanand · Y. Akiba · M. Alfred · N. Apadula · H. Asano · B. Azmoun · V. Babintsev · M. Bai and 334 other authors

   The invariant yield of electrons from open-heavy-flavor decays for $1<p_T<8$ GeV/$c$ at midrapidity $|y|<0.35$ in Au$+$Au collisions at $\sqrt{s_{{}_{NN}}}$ = 200 GeV has been measured by the PHENIX experiment at the Relativistic Heavy Ion Collider. A displaced-vertex analysis with the PHENIX silicon-vertex detector enables extraction of the fraction of charm and bottom hadron decays and unfolding of the invariant yield of parent charm and bottom hadrons. The nuclear-modification factors $R_{AA}$ for electrons from charm and bottom hadron decays and heavy-flavor hadrons show both a centrality and a quark-mass dependence, indicating suppression in the quark-gluon plasma produced in these collisions that is medium sized and quark-mass dependent.

   nucl-exPRC(2024)·28 citations
4. 04*

   Nonprompt direct-photon production in Au$+$Au collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV

   U.A. Acharya · A. Adare · C. Aidala · N.N. Ajitanand · Y. Akiba · M. Alfred · N. Apadula · H. Asano · B. Azmoun · V. Babintsev · M. Bai · N.S. Bandara and 325 other authors

   The measurement of the direct-photon spectrum from Au$+$Au collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV is presented by the PHENIX collaboration using the external-photon-conversion technique for 0\%--93\% central collisions in a transverse-momentum ($p_T$) range of 0.8--10 GeV/$c$. An excess of direct photons, above prompt-photon production from hard-scattering processes, is observed for $p_T<6$ GeV/$c$. Nonprompt direct photons are measured by subtracting the prompt component, which is estimated as $N_{\mathrm{coll}}$-scaled direct photons from $p$$+$$p$ collisions at 200 GeV, from the direct-photon spectrum. Results are obtained for $0.8<p_T<6.0$ GeV/$c$ and suggest that the spectrum has an increasing inverse slope from $\approx 0.2$ to 0.4 GeV/$c$ with increasing $p_T$, which indicates a possible sensitivity of the measurement to photons from earlier stages of the evolution of the collision. In addition, like the direct-photon production, the $p_T$-integrated nonprompt direct-photon yields also follow a power-law scaling behavior as a function of collision-system size. The exponent, $\alpha$, for the nonprompt component is found to be consistent with 1.1 with no apparent $p_T$ dependence.

   nucl-exPRC(2024)·66 citations
5. 05*

   Low Energy Protons as Probes of Hadronization Dynamics

   Carolina M. Robles Gajardo🇨🇱 · Alberto Accardi🇺🇸 · Mark D. Baker🇺🇸 · William K. Brooks🇨🇱 · Raphaël Dupré🇫🇷 · Mathieu Ehrhart🇫🇷 · Jorge A. López🇩🇪 · Zhoudunming Tu🇺🇸

   Energetic quarks liberated from hadrons in nuclear deep-inelastic scattering propagate through the nuclear medium, interacting with it via several processes. These include quark energy loss and nuclear interactions of forming hadrons. One manifestation of these interactions is the enhanced emission of low-energy charged particles, referred to as grey tracks. We use the theoretical components of the BeAGLE event generator to interpret grey track signatures of parton transport and hadron formation by comparing its predictions to E665 data. We extend the base version of BeAGLE by adding four different options for describing parton energy loss. The E665 data we used consists of multiplicity ratios for fixed-target scattering of 490 GeV muons on Xe normalized to deuterium as a function of the number of grey tracks. We compare multiplicity ratios for E665 grey tracks to the predictions of BeAGLE, varying the options and parameters to determine which physics phenomena can be identified by these data. We find that grey tracks are unaffected by modifications of the forward production. Thus their production must be dominated by interactions with hadrons in the backward region. This offers the advantage that selecting certain particles in the forward region is unlikely to bias a centrality selection. We see a strong correlation between the number of grey tracks and the in-medium path length. Our energy loss model does not reproduce the suppression observed in the projectile region. We see an underprediction of the proton production rate in backward kinematics, suggesting that a stronger source of interaction with the nuclear medium is needed for accurate modeling. These results lay an important foundation for future spectator tagging studies at both Jefferson Lab and at the Electron-Ion Collider, where neutron and proton grey track studies will be feasible down to very small momenta.

   ↳ hep-phhep-exnucl-exPRC(2022)·5 citations
6. 06*

   Evolution of the statistical disintegration of finite nuclei toward high energy

   A.S. Botvina🇩🇪 · N. Buyukcizmeci🇹🇷 · M. Bleicher🇩🇪

   We develop a statistical approach for the description of complex nuclei formation from dynamically produced baryons in high energy heavy-ion reactions. We consider a finite highly-excited expanding nuclear system formed after central nucleus-nucleus collisions. This system is sub-divided into primary equilibrated nucleon clusters. The final nuclei are produced after the decay of these excited clusters. By the successful comparison with the FOPI experimental data we prove the possibility of such a local equilibrium in nuclear matter with the temperature corresponding to the phase coexistence region. The regularities obtained in this new nuclei production mechanism are shown.

   ↳ nucl-thnucl-exPRC(2022)·16 citations
7. 07*

   Triangle singularities in the $T_{cc}^{+}\to D^{\ast +}{D}^0\to {\pi }^{+}{D}^0{D}^0$ decay width

   N.N. Achasov🇷🇺 · G.N. Shestakov🇷🇺

   The values of the masses of the particles involved in the decay of $T_{cc}^{+}\to D^{\ast +}{D}^0\to {\pi }^{+}{D}^0{D}^0$ suggest that due to the final state interactions in the transition vertex $T_{cc}^{+}\to D^{\ast +}{D}^0$ there may be triangle logarithmic singularities. We discuss their possible role and show that the tree approximation for calculating the decay widths $T_{cc}^{+}\to (D^{\ast +}{D}^0+D^{\ast 0}{D}^{+})\to {\pi }^{+}{D}^0{D}^0$, ${\pi }^0{D}^0{D}^{+}$, $\gamma D^0{D}^{+}$ is quite sufficient at the current level of measurement accuracy.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2022)·20 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.