Fri·Jul 4, 2014Friday·July 4, 2014

1. 01*

   High-resolution search for the ${\Theta }^{+}$ pentaquark via a pion-induced reaction at J-PARC

   J-PARC E19 Collaboration: M. Moritsu · S. Adachi · M. Agnello · S. Ajimura · K. Aoki · H. C. Bhang · B. Bassalleck · E. Botta · S. Bufalino · N. Chiga · H. Ekawa · P. Evtoukhovitch and 62 other authors

   The pentaquark ${\Theta }^{+}$ has been searched for via the ${\pi }^{-}p\to K^{-}X$ reaction with beam momenta of 1.92 and 2.01 GeV/$c$ at J-PARC. A missing mass resolution of 2 MeV (FWHM) was achieved but no sharp peak structure was observed. The upper limits on the production cross section averaged over the scattering angle from 2${}^{\circ }$ to 15${}^{\circ }$ in the laboratory frame were found to be less than 0.28 $\mu$b/sr at the 90\% confidence level for both the 1.92- and 2.01-GeV/$c$ data. The systematic uncertainty of the upper limits was controlled within 10\%. Constraints on the ${\Theta }^{+}$ decay width were also evaluated with a theoretical calculation using effective Lagrangian. The present result implies that the width should be less than 0.36 and 1.9 MeV for the spin-parity of $1/2^{+}$ and $1/2^{-}$, respectively.

   nucl-exhep-exnucl-thPRC(2014)·25 citations
2. 02*

   Experimental constraints on the $\omega$-nucleus real potential

   S. Friedrich🇩🇪 · K. Makonyi🇩🇪 · V. Metag🇩🇪 · D. Bayadilov🇩🇪 · B. Bantes🇩🇪 · R. Beck🇩🇪 · Y. A. Beloglazov🇩🇪 · S. Böse🇩🇪 · K.-T. Brinkmann🇩🇪 · Th. Challand🇨🇭 · V. Crede🇺🇸 · T. Dahlke🇩🇪 and 52 other authors

   In a search for $\omega$ mesic states, the production of $\omega$-mesons in coincidence with forward going protons has been studied in photon induced reactions on ${}^{12}$C for incident photon energies of 1250 - 3100 MeV. The ${\pi }^0\gamma$ pairs from decays of bound or quasi-free $\omega$-mesons have been measured with the CBELSA/TAPS detector system in coincidence with protons registered in the MiniTAPS forward array. Structures in the total energy distribution of the ${\pi }^0\gamma$ pairs, which would indicate the population and decay of bound $\omega {}^{11}$B states, are not observed. The ${\pi }^0\gamma$ cross section of 0.3 nb/MeV/sr observed in the bound state energy regime between -100 and 0 MeV may be accounted for by yield leaking into the bound state regime because of the large in-medium width of the $\omega$-meson. A comparison of the measured total energy distribution with calculations suggests the real part $V_0$ of the $\omega {}^{11}$B potential to be small and only weakly attractive with $V_0(\rho ={\rho }_0)=-15\pm$ 35(stat) $\pm$20(syst) MeV in contrast to some theoretical predictions of attractive potentials with a depth of 100 - 150 MeV.

   nucl-exPLB(2014)·20 citations
3. 03*

   Hyperfine structure and hyperfine anomaly in Pb

   J. R. Persson🇳🇴

   The hyperfine structure in the 6p2-configuration in lead has been analysed and the results is compared with calculations. The hyperfine anomaly and improved values of the nuclear magnetic moment for four lead isotopes is obtained, using the results from the analysis. The results open up for new measurements of the hyperfine structure in unstable lead isotopes, in order to extract information of the hyperfine anomaly and distribution of magnetisation in the nucleus.

   ↳ physics.atom-phnucl-exJ.Phys.Comm.(2018)·3 citations
4. 04*

   Information and statistics: a new paradigm in theoretical nuclear physics

   J. Piekarewicz🇺🇸 · Wei-Chia Chen🇺🇸 · F.J. Fattoyev🇺🇸

   Theoretical predictions of physical observables often involve extrapolations to regions that are poorly constrained by laboratory experiments and astrophysical observations. Without properly quantified theoretical errors, such model predictions are of very limited utility. In this contribution we use maximum-likelihood estimation to compute theoretical errors and assess correlations between physical observables. We illustrate the power and elegance of these methods using examples of both pedagogical and realistic interest. In particular, we implement a gaussian approximation to the likelihood function to develop a new relativistic effective interaction constrained by ground-state properties of finite nuclei, their monopole response, and masses of neutron stars.

   ↳ nucl-thastro-ph.SRnucl-exJ.Phys.G(2015)·24 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.