Thu·Jun 24, 2021Thursday·June 24, 2021

1. 01*

   Photoexcitation of ${}^{76}$Ge

   R. Schwengner (1)🇩🇪 · R. Massarczyk (2)🇺🇸 · K. Schmidt (1)🇩🇪 · K. Zuber (3)🇩🇪 · R. Beyer (1)🇩🇪 · D. Bemmerer (1)🇩🇪 · S. Hammer (1)🇩🇪 · A. Hartmann (1)🇩🇪 · T. Hensel (1,3)🇩🇪 · H. F. Hoffmann (1,3)🇩🇪 · A. R. Junghans (1)🇩🇪 · T. Kögler (1,4)🇩🇪 and 6 other authors

   The dipole strength of the nuclide ${}^{76}$Ge was studied in photon-scattering experiments using bremsstrahlung produced with electron beams of energies of 7.8 and 12.3 MeV at the $\gamma$ELBE facility. We identified 210 levels up to an excitation energy of 9.4 MeV and assigned spin $J$ = 1 to most of them. The quasicontinuum of unresolved transitions was included in the analysis of the spectra and the intensities of branching transitions were estimated on the basis of simulations of statistical $\gamma$-ray cascades. The photoabsorption cross section up to the neutron-separation energy was determined and is compared with predictions of the statistical reaction model. The derived photon strength function is compared with results of experiments using other reactions.

   nucl-exPRC(2022)·9 citations
2. 02*

   Joint Determination of Reactor Antineutrino Spectra from ${}^{235}$U and ${}^{239}$Pu Fission by Daya Bay and PROSPECT

   Daya Bay Collaboration · PROSPECT Collaboration: F. P. An · M. Andriamirado · A. B. Balantekin · H. R. Band · C. D. Bass · D. E. Bergeron · D. Berish · M. Bishai · S. Blyth · N. S. Bowden · C. D. Bryan and 229 other authors

   A joint determination of the reactor antineutrino spectra resulting from the fission of ${}^{235}$U and ${}^{239}$Pu has been carried out by the Daya Bay and PROSPECT collaborations. This Letter reports the level of consistency of ${}^{235}$U spectrum measurements from the two experiments and presents new results from a joint analysis of both data sets. The measurements are found to be consistent. The combined analysis reduces the degeneracy between the dominant ${}^{235}$U and ${}^{239}$Pu isotopes and improves the uncertainty of the ${}^{235}$U spectral shape to about 3\%. The ${}^{235}$U and ${}^{239}$Pu antineutrino energy spectra are unfolded from the jointly deconvolved reactor spectra using the Wiener-SVD unfolding method, providing a data-based reference for other reactor antineutrino experiments and other applications. This is the first measurement of the ${}^{235}$U and ${}^{239}$Pu spectra based on the combination of experiments at low- and highly enriched uranium reactors.

   nucl-exhep-exPRL(2022)·38 citations
3. 03*

   Azimuthal correlations in photoproduction and deep inelastic $\mathbf{ep}$ scattering at HERA

   ZEUS collaboration · I. Abt · R. Aggarwal · V. Aushev · O. Behnke · A. Bertolin · I. Bloch · I. Brock · N.H. Brook · R. Brugnera · A. Bruni · P.J. Bussey and 72 other authors

   Collective behaviour of final-state hadrons, and multiparton interactions are studied in high-multiplicity $ep$ scattering at a centre-of-mass energy $\sqrt{s}=318$ GeV with the ZEUS detector at HERA. Two- and four-particle azimuthal correlations, as well as multiplicity, transverse momentum, and pseudorapidity distributions for charged-particle multiplicities $N_{\text{c}h}\ge 20$ are measured. The dependence of two-particle correlations on the virtuality of the exchanged photon shows a clear transition from photoproduction to neutral current deep inelastic scattering. For the multiplicities studied, neither the measurements in photoproduction processes nor those in neutral current deep inelastic scattering indicate significant collective behaviour of the kind observed in high-multiplicity hadronic collisions at RHIC and the LHC. Comparisons of PYTHIA predictions with the measurements in photoproduction strongly indicate the presence of multiparton interactions from hadronic fluctuations of the exchanged photon.

   ↳ hep-exnucl-exJHEP(2021)·27 citations
4. 04*

   ${\eta }^{{(}^{\prime })}\to {\pi }^{+}{\pi }^{-}{\gamma }^{(\ast )}$ in large-$N_c$ chiral perturbation theory

   Patricia Bickert🇩🇪 · Stefan Scherer🇩🇪

   We present a calculation of the decays ${\eta }^{{(}^{\prime })}\to {\pi }^{+}{\pi }^{-}{\gamma }^{(\ast )}$ at the one-loop level up to and including next-to-next-to-leading order (NNLO) in large-$N_c$ chiral perturbation theory. The numerical evaluation of the results is performed successively at LO, NLO, and NNLO, fitting the relevant low-energy constants to the available experimental data. We discuss the widths and decay spectra of ${\eta }^{{(}^{\prime })}\to {\pi }^{+}{\pi }^{-}\gamma$ as well as ${\eta }^{{(}^{\prime })}\to {\pi }^{+}{\pi }^{-}{l}^{+}{l}^{-}$, with $l=e,\mu$.

   ↳ hep-phnucl-exnucl-thPRD(2021)·1 citation
5. 05*

   Enhanced D-D Fusion Rates when the Coulomb Barrier Is Lowered by Electrons

   Alfred Y. Wong · Alexander Gunn · Allan X. Chen · Chun-Ching Shih · Mason J. Guffey

   A profusion of unbound, low-energy electrons creates a local electric field that reduces Coulomb potential and increases quantum tunneling probability for pairs of nuclei. Neutral beam-target experiments on deuterium-deuterium fusion reactions, observed with neutron detectors, show percentage increases in fusion products are consistent with electron-screening predictions from Schrodinger wave mechanics. Experiments performed confirm that observed fusion rate enhancement with a negatively biased target is primarily due to changes to the fusion cross section, rather than simply acceleration due to electrostatic forces.

   ↳ physics.plasm-phnucl-ex0 citations
6. 06*

   Fragmentation of jets containing a prompt J$/\psi$ meson in PbPb and pp collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV

   CMS Collaboration

   Jets containing a prompt J$/\psi$ meson are studied in lead-lead collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV, using the CMS detector at the LHC. Jets are selected to be in the transverse momentum range of 30 $<$ $p_{\mathrm{T}}$ $<$ 40 GeV. The J$/\psi$ yield in these jets is evaluated as a function of the jet fragmentation variable $z$, the ratio of the J$/\psi$ $p_{\mathrm{T}}$ to the jet $p_{\mathrm{T}}$. The nuclear modification factor, $R_{\mathrm{AA}}$, is then derived by comparing the yield in lead-lead collisions to the corresponding expectation based on proton-proton data, at the same nucleon-nucleon center-of-mass energy. The suppression of the J$/\psi$ yield shows a dependence on $z$, indicating that the interaction of the J$/\psi$ with the quark-gluon plasma formed in heavy ion collisions depends on the fragmentation that gives rise to the J$/\psi$ meson.

   ↳ hep-exnucl-exPLB(2022)·51 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.