Wed·May 25, 2016Wednesday·May 25, 2016

1. 01*

   Photoproduction of leptophobic bosons

   Cristiano Fanelli🇺🇸 · Mike Williams🇺🇸

   We propose a search for photoproduction of leptophobic bosons that couple to quarks at the GlueX experiment at Jefferson Lab. We study in detail a new gauge boson that couples to baryon number $B$, and estimate that $\gamma p\to pB$ will provide the best sensitivity for $B$ masses above 0.5 GeV. This search will also provide sensitivity to other proposed dark-sector states that couple to quarks. Finally, our results motivate a similar search for $B$ boson electroproduction at the CLAS experiment.

   ↳ hep-phhep-exnucl-exJ.Phys.G(2017)·19 citations
2. 02*

   Systematics of dynamic moment of inertia in super-deformed bands in Mass ~150 region

   S. Roy🇮🇳

   An empirical semi-classical model have been proposed to investigate the nature of dynamic moment-of-inertia , of the super-deformed (SD) bands in nuclei of mass 150 region. The model incorporates an additional frequency dependent distortion, to the dynamic moment-of-inertia term akin to a vibrational component to explain the extreme spin structure of these bands. Using this model two separate components to the dynamic moment of inertia, ${\Im }^{(2)}$ have been identified for the SD band structure for the mass 150 region. Three distinct nature of the moment-of-inertia, also have been identified using the two parameter model.

   ↳ nucl-thnucl-ex0 citations
3. 03*

   Multipion correlations induced by isospin conservation of coherent emission

   Dhevan Gangadharan🇺🇸

   Recent measurements have revealed a significant suppression of multipion Bose-Einstein correlations in heavy-ion collisions at the LHC. The suppression may be explained by postulating coherent pion emission. Typically, the suppression of Bose-Einstein correlations due to coherence is taken into account with the coherent state formalism in quantum optics. However, since charged pion correlations are most often measured, the additional constraint of isospin conservation, which is absent in quantum optics, needs to be taken into account. As a consequence, correlations emerge between pions of opposite charge. A calculation of the correlations induced by isospin conservation of coherent emission is made for two, three- and four-pion correlation functions and compared to the data from the LHC.

   ↳ nucl-thnucl-exPLB(2016)·1 citation
4. 04*

   Comment on "Structure effects in the ${}^{15}$N(n,$\gamma$)${}^{16}$N radiative capture reaction from the Coulomb dissociation of ${}^{16}$N"

   Peter Mohr🇭🇺

   In their recent study Neelam, Shubhchintak, and Chatterjee have claimed that "it would certainly be useful to perform a Coulomb dissociation experiment to find the low energy capture cross section for the reaction" ${}^{15}$N(n,$\gamma$)${}^{16}$N. However, it is obvious that a Coulomb dissociation experiment cannot constrain this capture cross section because the dominating branchings of the capture reaction lead to excited states in ${}^{16}$N which do not contribute in a Coulomb dissociation experiment. An estimate of the total ${}^{15}$N(n,$\gamma$)${}^{16}$N cross section from Coulomb dissociation of ${}^{16}$N requires a precise knowledge of the $\gamma$-ray branchings in the capture reaction. Surprisingly, the calculation of Neelam, Shubhchintak, and Chatterjee predicts a strongly energy-dependent ground state branching of the order of 0.05\% to 0.6\% at energies between 100 and 500 keV which is almost 2 orders of magnitude below calculations in the direct capture model. Additionally, this calculation of Neelam, Shubhchintak, and Chatterjee deviates significantly from the expected energy dependence for $p$-wave capture.

   ↳ nucl-thnucl-exPRC(2016)·0 citations
5. 05*

   Nucleosynthesis of ${}^{92}$Nb and the relevance of the low-lying isomer at 135.5 keV

   Peter Mohr🇭🇺

   Background: Because of its half-life of about 35 million years, 92Nb is considered as a chronometer for nucleosynthesis events prior to the birth of our sun. The abundance of 92Nb in the early solar system can be derived from meteoritic data. It has to be compared to theoretical estimates for the production of 92Nb to determine the time between the last nucleosynthesis event before the formation of the early solar system. Purpose: The influence of a low-lying short-lived isomer on the nucleosynthesis of 92Nb is analyzed. The thermal coupling between the ground state and the isomer via so-called intermediate states affects the production and survival of 92Nb. Method: The properties of the lowest intermediate state in 92Nb are known from experiment. From the lifetime of the intermediate state and from its decay branchings, the transition rate from the ground state to the isomer and the effective half-life of 92Nb are calculated as a function of the temperature. Results: The coupling between the ground state and the isomer is strong. This leads to thermalization of ground state and isomer in the nucleosynthesis of 92Nb in any explosive production scenario and almost 100% survival of 92Nb in its ground state. However, the strong coupling leads to a temperature-dependent effective half-life of 92Nb which makes the 92Nb survival very sensitive to temperatures as low as about 8 keV, thus turning 92Nb at least partly into a thermometer. Conclusions: The low-lying isomer in 92Nb does not affect the production of 92Nb in explosive scenarios. In retrospect this validates all previous studies where the isomer was not taken into account. However, the dramatic reduction of the effective half-life at temperatures below 10 keV may affect the survival of 92Nb after its synthesis in supernovae which are the most likely astrophysical site for the nucleosynthesis of 92Nb.

   ↳ nucl-thnucl-exPRC(2016)·6 citations
6. 06*

   Results on heavy ion collisions at LHCb

   Yanxi Zhang (for the LHCb collaboration)🇫🇷

   Heavy flavor production is important in heavy ion collisions to study both cold and hot nuclear matter effects. The LHCb experiment can make unique contribution to heavy ion physics, owing to the full particle identification of the detector in the forward region and the ability to collect fixed target data with proton or lead beams. This report describes recent results with proton-lead collision data collected in 2013 and the prospect of heavy-ion studies at LHCb.

   ↳ hep-exnucl-ex5 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.