Thu·Jun 7, 2018Thursday·June 7, 2018

1. 01*

   Study of 12C(p,p',gamma)12C reaction

   M. Dhibar · I. Mazumdar🇮🇳 · G. Anil Kumar · S. P. Weppner · A. K. Rhine Kumar🇮🇳 · S. M. Patel · P. B. Chavan

   In the present work, we report our in depth study of 12C(p,p'gamma)12C reaction both experimentally and theoretically with proton beam energy ranging from 8 MeV to 22 MeV. The angular distributions were measured at six different angles. We discuss the gamma angular distributions, total cross sections values for 4.438, 9.64, 12.7 and 15.1 MeV states. We also describe the theoretical interpretation of our measurements using optical model analysis. We also report the branching ratios from our measurements. For the first time, we have measured the the cross section and branching ratio for the 9.64 MeV state.

   nucl-ex2 citations
2. 02*

   Quenching of $g_{\mathrm{A}}$ deduced from the $\beta$-spectrum shape of ${}^{113}$Cd measured with the COBRA experiment

   Lucas Bodenstein-Dresler🇩🇪 · Yingjie Chu🇩🇪 · Daniel Gehre🇩🇪 · Claus Gößling🇩🇪 · Arne Heimbold🇩🇪 · Christian Herrmann🇩🇪 · Rastislav Hodak🇨🇿 · Joel Kostensalo🇫🇮 · Kevin Kröninger🇩🇪 · Julia Küttler🇩🇪 · Christian Nitsch🇩🇪 · Thomas Quante🇩🇪 and 8 other authors

   A dedicated study of the quenching of the weak axial-vector coupling strength $g_{\mathrm{A}}$ in nuclear processes has been performed by the COBRA collaboration. This investigation is driven by nuclear model calculations which show that the $\beta$-spectrum shape of the fourfold forbidden non-unique decay of ${}^{113}$Cd strongly depends on the effective value of $g_{\mathrm{A}}$. Using an array of CdZnTe semiconductor detectors, 45 independent ${}^{113}$Cd spectra were obtained and interpreted in the context of three nuclear models. The resulting effective mean values are ${\bar{g}}_{\mathrm{A}}(\text{ISM})=0.915\pm 0.007$, ${\bar{g}}_{\mathrm{A}}(\text{MQPM})=0.911\pm 0.013$ and ${\bar{g}}_{\mathrm{A}}(\text{IBFM-2})=0.955\pm 0.022$. These values agree well within the determined uncertainties and deviate significantly from the free value of $g_{\mathrm{A}}$. This can be seen as a first step towards answering the long-standing question regarding quenching effects related to $g_{\mathrm{A}}$ in low-energy nuclear processes.

   nucl-exPLB(2020)·50 citations
3. 03*

   $K^0\Lambda$ photoproduction off the neutron with nucleon resonances

   Sang-Ho Kim🇰🇷 · Hyun-Chul Kim🇰🇷

   We investigate kaon photoproduction off the neutron target, i.e., $\gamma n\to K^0\Lambda$, focusing on the role of nucleon resonances given in the Review of Particle Data Group in the range of $\sqrt{s}\approx 1600-2200$ MeV. We employ an effective Lagrangian method and a Regge approach. The strong couplings of nucleon resonances with $K\Lambda$ vertices are constrained by quark model predictions. The numerical results of the total and differential cross sections are found to be in qualitative agreement with the recent CLAS and FOREST experimental data. We discuss the effects of the narrow nucleon resonance $N(1685,1/2^{+})$ on both the total and differential cross sections near the threshold energy. In addition, we present the results of the beam asymmetry as a prediction.

   ↳ hep-phhep-exnucl-exnucl-thPLB(2018)·13 citations
4. 04*

   Low-$p_T$ $e^{+}{e}^{-}$ pair production in Au$+$Au collisions at $\sqrt{s_{NN}}$ = 200 GeV and U$+$U collisions at $\sqrt{s_{NN}}$ = 193 GeV at STAR

   J. Adam🇺🇸 · L. Adamczyk🇵🇱 · J. R. Adams🇺🇸 · J. K. Adkins🇺🇸 · G. Agakishiev🇷🇺 · M. M. Aggarwal🇮🇳 · Z. Ahammed🇮🇳 · N. N. Ajitanand🇺🇸 · I. Alekseev🇷🇺 · D. M. Anderson🇺🇸 · R. Aoyama🇯🇵 · A. Aparin🇷🇺 and 338 other authors

   We report first measurements of $e^{+}{e}^{-}$ pair production in the mass region 0.4 $<M_{ee}<$ 2.6 GeV/$c^2$ at low transverse momentum ($p_T<$ 0.15 GeV/$c$) in non-central Au$+$Au collisions at $\sqrt{s_{NN}}$ = 200 GeV and U$+$U collisions at $\sqrt{s_{NN}}$ = 193 GeV. Significant enhancement factors, expressed as ratios of data over known hadronic contributions, are observed in the 40-80% centrality of these collisions. The excess yields peak distinctly at low-$p_T$ with a width ($\sqrt{⟨p_T^2⟩}$) between 40 to 60 MeV/$c$. The absolute cross section of the excess depends weakly on centrality while those from a theoretical model calculation incorporating an in-medium broadened $\rho$ spectral function and radiation from a Quark Gluon Plasma or hadronic cocktail contributions increase dramatically with increasing number of participant nucleons. Model calculations of photon-photon interactions generated by the initial projectile and target nuclei describe the observed excess yields but fail to reproduce the $p_T^2$ distributions.

   ↳ hep-exnucl-exPRL(2018)·140 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.