Thu·Jun 30, 2022Thursday·June 30, 2022

1. 01*

   Resonance excitations in ${}^7$Be(d,p)${}^8$Be${}^{\ast }$ to address the cosmological lithium problem

   Sk M. Ali🇮🇳 · D. Gupta🇮🇳 · K. Kundalia🇮🇳 · Swapan K. Saha🇮🇳 · O. Tengblad🇪🇸 · J.D. Ovejas🇪🇸 · A. Perea🇪🇸 · I. Martel🇪🇸 · J. Cederkall🇸🇪 · J. Park🇸🇪 · S. Szwec🇫🇮

   The anomaly in lithium abundance is a well-known unresolved problem in nuclear astrophysics. A recent revisit to the problem tried the avenue of resonance enhancement to account for the primordial ${}^7$Li abundance in standard big-bang nucleosynthesis (BBN). Prior measurements of the ${}^7$Be(d,p)${}^8$Be* reaction could not account for the individual contributions of the different excited states involved, particularly at higher energies close to the Q-value of the reaction. We carried out an experiment at HIE-ISOLDE, CERN to study this reaction at E${}_{cm}$ = 7.8 MeV, populating excitations up to 22 MeV in ${}^8$Be for the first time. The angular distributions of the several excited states have been measured and the contributions of the higher excited states in the total cross section at the relevant big-bang energies were obtained by extrapolation to the Gamow window using the TALYS code. The results show that by including the contribution of the 16.63 MeV state, the maximum value of the total S-factor inside the Gamow window comes out to be 167 MeV b as compared to earlier estimate of 100 MeV b. However, this still does not account for the lithium discrepancy.

   nucl-exPRL(2022)·24 citations
2. 02*

   Isospin-symmetry implications for nuclear two-body distributions and short-range correlations

   R. Weiss🇺🇸 · A. Lovato🇺🇸 · R. B. Wiringa🇺🇸

   We study the implications of isospin symmetry in nuclear systems on two-body distributions and derive relations between different densities or momentum distributions of a given nucleus or of different nuclei in the same isospin multiplet. A connection between neutrinoless double beta decay transition of mirror nuclei and two-body densities is also obtained. The relations are numerically verified by means of quantum Monte Carlo calculations. We discuss the relevance of these results to the analysis of nuclear short-range correlations and also show that isospin symmetry allows us to extract information about the spectator nucleons when a short-range correlated pair is formed.

   ↳ nucl-thnucl-exPRC(2022)·2 citations
3. 03*

   Effect of thermal gluon absorption and medium fluctuations on heavy flavour nuclear modification factor at RHIC and LHC energies

   Ashik Ikbal Sheikh🇺🇸

   The presence of thermal gluons reduces the stimulated gluon emission off a heavy quark propagating in the quark-gluon plasma (QGP) while absorption causes reduction of the radiative energy loss. On the other hand, the chromo-electromagnetic field fluctuations present in the QGP lead to collisional energy gain of the heavy quark. The net effect of the thermal gluon absorption and field fluctuations is a reduction of the total energy loss of the heavy quark, prominent at the lower momenta. We consider both kind of the energy gains along with the usual losses, and compute the nuclear modification factor ($R_{AA}$) of heavy mesons, viz., $D$ and $B$ mesons. The calculations have been compared with the experimental measurements in Au-Au collisions at $\sqrt{s_{NN}}=200$ GeV from STAR and PHENIX experiments at the RHIC and Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV and $5.02$ TeV from CMS and ALICE experiments at the LHC. We find a significant effect of the total energy gain due to thermal gluon absorption and field fluctuations on heavy flavour suppression, especially at the lower transverse momenta.

   ↳ hep-phnucl-exnucl-thEPJA(2021)·1 citation
4. 04*

   Investigating the coalescence-inspired sum rule for light nuclei and hypernuclei in heavy-ion collisions

   Ashik Ikbal Sheikh🇺🇸

   A data-driven idea is presented to test if light nuclei and hypernuclei obey the coalescence-inspired sum rule, i.e., to test if the flow of a light nucleus or hypernucleus is the summed flow of each of its constituents. Here, the mass difference and charge difference among the constituents of light nuclei and hypernuclei are treated appropriately. The idea is applied to the available data for $\sqrt{s_{NN}}=3$ GeV fixed-target Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC), published by the STAR collaboration. It is found that the sum rule for light nuclei is approximately valid near mid-rapidity ($-0.3<y<0$), but there is a clear violation of the sum rule at large rapidity ($y<-0.3$). The Jet AA Microscopic Transport Model (JAM), with baryonic mean-field plus nucleon coalescence, generates a similar pattern as obtained from the experimental data. In the present approach, the rapidity dependence of directed flow of the hypernuclei ${}_{\mathrm{\Lambda }}^3\mathrm{H}$ and ${}_{\mathrm{\Lambda }}^4\mathrm{H}$ is predicted in a model-independent way for $\sqrt{s_{NN}}=3$ GeV Au+Au collisions, which will be explored by ongoing and future measurements from STAR.

   ↳ nucl-thhep-exhep-phnucl-exPRC(2022)·2 citations
5. 05*

   Quantum Chromodynamics Resolution of the ATOMKI Anomaly in ${}^4\mathrm{He}$ Nuclear Transitions

   Valery Kubarovsky🇺🇸 · Jennifer Rittenhouse West🇺🇸 · Stanley J. Brodsky🇺🇸

   Observations of anomalous angular correlations in electron-positron pairs produced from excited states of ${}^4$He, ${}^8$Be and ${}^{12}$C nuclei have been suggested as due to the creation and subsequent decay of a new light particle of mass $\sim$17 MeV. In this work, we investigate the possibility that the source of the observed signals is a set of new excitation channels created by the 12-quark hidden-color Fock state within the ${}^4\mathrm{He}$ nuclear wavefunction dubbed the ``hexadiquark.'' We calculate the invariant $e^{+}{e}^{-}$ mass spectrum for the electromagnetic transition from a new excitation of ${}^4$He, estimating its differential and total decay width. We find that we can fit the shape of the anomalous signal with the QCD Fock state at excitation energy ${\mathrm{E}}^{\ast }=17.9\pm 1$ MeV and a Gaussian form factor for the electromagnetic decay. We address the physical issues with the fit parameters using properties of the hexadiquark state, in particular the three weakly repulsive $6_{\mathrm{C}}$ interactions of $\mathrm{SU}(3{)}_{\mathrm{C}}$ between diquark pairs. Experimental tests of our model are described in detail. In light of this work, we emphasize the need for independent experimental confirmation or refutation of the ATOMKI results as well as dedicated experiments to search for the proposed new excitations of ${}^4\mathrm{He}$ and other $\alpha$-cluster nuclei.

   ↳ hep-phnucl-exnucl-thPRC(2025)·16 citations
6. 06*

   Theoretical study on the contributions of $\omega$ meson to the $X(3872)\to J/\psi {\pi }^{+}{\pi }^{-}$ and $J/\psi {\pi }^{+}{\pi }^{-}{\pi }^0$ decays

   Hao-Nan Wang🇨🇳 · Qian Wang🇨🇳 · Ju-Jun Xie🇨🇳

   With the newly measurements of $X(3872)\to J/\psi {\pi }^{+}{\pi }^{-}$ from LHCb Collaboration, in addition to the dominant contribution from the ${\rho }^0$ meson, we perform a theoretical study on the contribution of $\omega$ meson in the $X(3872)\to J/\psi {\pi }^{+}{\pi }^{-}$ and $X(3872)\to J/\psi {\pi }^{+}{\pi }^{-}{\pi }^0$ processes. It is found that the recent experimental measurements on the ${\pi }^{+}{\pi }^{-}$ invariant mass distributions can be well reproduced, and the ratio of the couplings between $X(3872)\to J/\psi {\rho }^0$ and $X(3872)\to J/\psi \omega$ is also evaluated. Within the parameters extracted from the ${\pi }^{+}{\pi }^{-}$ invariant mass distributions of the $X(3872)\to J/\psi {\pi }^{+}{\pi }^{-}$ process, the branching fractions of the $X(3872)\to J/\psi \omega$ channel relative to that of the $X(3872)\to J/\psi {\pi }^{+}{\pi }^{-}{\pi }^0$ channel and the ${\pi }^{+}{\pi }^{-}{\pi }^0$ invariant mass distributions of the $X(3872)\to J/\psi {\pi }^{+}{\pi }^{-}{\pi }^0$ decay are calculated, which gives a hint for the further high-statistic experiment.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2022)·7 citations
7. 07*

   Two-photon exchange in (muonic) deuterium at N3LO in pionless effective field theory

   Vadim Lensky (JGU Mainz)🇩🇪 · Franziska Hagelstein (JGU Mainz and PSI Villigen)🇩🇪 · Vladimir Pascalutsa (JGU Mainz)🇩🇪

   We present a study of the two-photon-exchange ($2\gamma$-exchange) corrections to the $S$-levels in muonic ($\mu$D) and ordinary (D) deuterium within the pionless effective field theory (pionless EFT). Our calculation proceeds up to next-to-next-to-next-to-leading order (N3LO) in the pionless EFT expansion. The only unknown low-energy constant entering the calculation at this order corresponds to the coupling of a longitudinal photon to the nucleon-nucleon system. To minimise its correlation with the deuteron charge radius, it is extracted using the information about the hydrogen-deuterium isotope shift. We find the elastic $2\gamma$-exchange contribution in $\mu$D larger by several standard deviations than obtained in other recent calculations. This discrepancy ameliorates the mismatch between theory and experiment on the size of $2\gamma$-exchange effects, and is attributed to the properties of the deuteron elastic charge form factor parametrisation used to evaluate the elastic contribution. We identify a correlation between the deuteron charge and Friar radii, which can help one to judge how well a form factor parametrisation describes the low-virtuality properties of the deuteron. We also evaluate the higher-order $2\gamma$-exchange contributions in $\mu$D, generated by the single-nucleon structure and expected to be the most important terms beyond N3LO. The uncertainty of the theoretical result is dominated by the truncation of the pionless EFT series and is quantified using a Bayesian approach. The resulting extractions of the deuteron charge radius from the $\mu$D Lamb shift, the $2S-1S$ transition in D, and the $2S-1S$ hydrogen-deuterium isotope shift, with the respective $2\gamma$-exchange effects evaluated in a unified pionless EFT approach, are in perfect agreement.

   ↳ nucl-thhep-phnucl-exphysics.atom-phEPJA(2022)·6 citations
8. 08*

   Total Neutron Cross-section Measurement on CH with a Novel 3D-projection Scintillator Detector

   A. Agarwal · H. Budd · J. Capo · J. Chaves · P. Chong · G. Christodoulou · M. Danilov · A. Dergacheva · A. De Roeck · N. Dokania · D. Douqa · K. Dugas and 50 other authors

   In order to extract neutrino oscillation parameters, precision long-baseline neutrino oscillation experiments rely on detailed models of neutrino interactions with nuclei. These models constitute an important source of systematic uncertainty, partially because detectors to date have been blind to final state neutrons. Three-dimensional projection scintillator trackers comprise components of the near detectors of the next generation long-baseline neutrino experiments. Due to the good timing resolution and fine granularity, this technology is capable of measuring neutron kinetic energy in neutrino interactions on an event-by-event basis and will provide valuable data for refining neutrino interaction models and ways to reconstruct neutrino energy. Two prototypes have been exposed to the neutron beamline at Los Alamos National Laboratory (LANL) in both 2019 and 2020, with neutron energies between 0 and 800 MeV. In order to demonstrate the capability of neutron detection, the total neutron-scintillator cross section is measured and compared to external measurements. The measured total neutron cross section in scintillator between 98 and 688 MeV is 0.36 $\pm$ 0.05 barn.

   ↳ physics.ins-dethep-exnucl-exPLB(2023)·27 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.