Tue·Jun 5, 2018Tuesday·June 5, 2018

1. 01*

   Search for Variations of Po-213 Half-Life

   E.N.Alexeyev · Yu.M.Gavrilyuk · A.M.Gangapshev · A.M.Gezhaev · V.V.Kazalov · V.V.Kuzminov · S.I.Panasenko · S.S.Ratkevich

   A device with the parent ${}^{229}$Th source was constructed to search for variations of the daughter ${}^{213}$Po half-life ($T_{1/2}=4.2$ $\mu$s). A solar-daily variation with amplitude $A_{So}=(5.3\pm 1.1)\times 10^{-4}$, a lunar-daily variation with amplitude $A_L=(4.8\pm 2.1)\times 10^{-4}$, and a sidereal-daily variation with amplitude $A_S=(4.2\pm 1.7)\times 10^{-4}$ were found upon proceeding the data series over a 622-day interval (from July 2015 to March 2017). The ${}^{213}$Po half-life mean value is found to be $T_{1/2}=3.705\pm 0.001$ $\mu$s. The obtained half-life is in good agreement with some of the literature values obtained with great accuracy.

   nucl-exPhys.Part.Nucl.(2018)·9 citations
2. 02*

   Production of dark-matter bound states in the early universe by three-body recombination

   Eric Braaten🇺🇸 · Daekyoung Kang🇨🇳 · Ranjan Laha🇩🇪

   The small-scale structure problems of the universe can be solved by self-interacting dark matter that becomes strongly interacting at low energy. A particularly predictive model for the self-interactions is resonant short-range interactions with an S-wave scattering length that is much larger than the range. The velocity dependence of the cross section in such a model provides an excellent fit to self-interaction cross sections inferred from dark-matter halos of galaxies and clusters of galaxies if the dark-matter mass is about 19 GeV and the scattering length is about 17 fm. Such a model makes definite predictions for the few-body physics of weakly bound clusters of the dark-matter particles. The formation of the two-body bound cluster is a bottleneck for the formation of larger bound clusters. We calculate the production of two-body bound clusters by three-body recombination in the early universe under the assumption that the dark matter particles are identical bosons, which is the most favorable case. If the dark-matter mass is 19 GeV and the scattering length is 17 fm, the fraction of dark matter in the form of two-body bound clusters can increase by as much as 4 orders of magnitude when the dark-matter temperature falls below the binding energy, but its present value remains less than 10^(-6). The present fraction can be increased to as large as 10^(-3) by relaxing the constraints from small-scale structure and decreasing the mass of the dark matter particle.

   ↳ hep-phastro-ph.COhep-exnucl-ex+1JHEP(2018)·38 citations
3. 03*

   Microscopic description of proton-induced spallation reactions with the Constrained Molecular Dynamics (CoMD) Model

   A. Assimakopoulou · G.A. Souliotis🇬🇷 · A. Bonasera🇺🇸 · A. Botvina🇩🇪 · N.G. Nicolis · M. Veselsky🇸🇰

   We studied the complete dynamics of the proton-induced spallation process with the microscopic framework of the Constrained Molecular Dynamics (CoMD) Model. We performed calculations of proton-induced spallation reactions on 181Ta, 208Pb, and 238U targets with the CoMD model and compared the results with a standard two-step approach based on an intranuclear cascade model (INC) followed by a statistical deexcitation model. The calculations were also compared with recent experimental data from the literature. Our calculations showed an overall satisfactory agreement with the experimental data and suggest further improvements in the models. We point out that this CoMD study represents the first complete dynamical description of spallation reactions with a microscopic N-body approach and may lead to advancements in the physics-based modelling of the spallation process.

   ↳ nucl-thnucl-exJ.Phys.G(2019)·4 citations
4. 04*

   Transversity generalized parton distributions for the deuteron

   W. Cosyn🇧🇪 · B. Pire🇫🇷

   Transversity generalized parton distributions (GPDs) appear as scalar functions in the decomposition of off-forward quark-quark and gluon-gluon correlators with a parton helicity flip. For a spin 1 hadron, we find 9 transversity GPDs for both quarks and gluons at leading twist 2. We study these twist-2 chiral odd quark transversity GPDs for the deuteron in a light cone convolution model, based on the impulse approximation, and using the lowest Fock-space state for the deuteron.

   ↳ hep-phnucl-exnucl-thPRD(2018)·35 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.