Tue·Jan 3, 2017Tuesday·January 3, 2017

1. 01*

   Study of $\eta$ and ${\eta }^{\prime }$ photoproduction at MAMI

   V. L. Kashevarov🇩🇪 · P. Ott🇩🇪 · S. Prakhov🇩🇪 · P. Adlarson🇩🇪 · F. Afzal🇩🇪 · Z. Ahmed🇨🇦 · C. S. Akondi🇺🇸 · J. R. M. Annand🇬🇧 · H. J. Arends🇩🇪 · R. Beck🇩🇪 · A. Braghieri🇮🇹 · W. J. Briscoe🇺🇸 and 78 other authors

   The reactions $\gamma p\to \eta p$ and $\gamma p\to {\eta }^{\prime }p$ have been measured from their thresholds up to the center-of-mass energy $W=1.96$GeV with the tagged-photon facilities at the Mainz Microtron, MAMI. Differential cross sections were obtained with unprecedented accuracy, providing fine energy binning and full production-angle coverage. A strong cusp is observed in the total cross section and excitation functions for $\eta$ photoproduction at the energies in vicinity of the ${\eta }^{\prime }$ threshold, $W=1896$MeV ($E_{\gamma }=1447$MeV). This behavior is explained in a revised $\eta$MAID isobar model by a significant branching of the $N(1895)1/2^{-}$ nucleon resonance to both, $\eta p$ and ${\eta }^{\prime }p$, confirming the existence and constraining the properties of this poorly known state.

   nucl-exhep-exhep-phPRL(2017)·77 citations
2. 02*

   Forward-backward multiplicity correlations at the LHC from independent sources

   Adam Olszewski🇵🇱 · Wojciech Broniowski🇵🇱

   It is argued that the superposition approach, where partons are independently emitted from longitudinally extended sources in the early stage, is fully compatible with the experimental results for the forward-backward multiplicity correlations in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76\text{ TeV}$. The pertinent correlation analysis is based on the PhD Thesis of Ref. [1], which includes an unpublished analysis of data taken by the ALICE Collaboration. Our calculations show that in the experimentally covered pseudorapidity range $\Delta \eta =1.2$, the initial sources in the backward and forward bins are maximally correlated, which complies to the string-like interpretation of the underlying early-stage production mechanism.

   ↳ nucl-thnucl-exActa Phys.Polon.B(2017)·1 citation
3. 03*

   Legendre Analysis of Differential Distributions in Hadronic Reactions

   Yakov I. Azimov (PNPI)🇷🇺 · Igor I. Strakovsky (GWU)🇺🇸 · William J. Briscoe (GWU)🇺🇸 · Ron L. Workman (GWU)🇺🇸

   Modern experimental facilities, such as CBELSA, ELPH, JLab, MAMI and SPring-8 have provided a tremendous volume of data, often with wide energy and angular coverage, and with increasing precision. For reactions with two hadrons in the final state, these data are often presented as multiple sets of panels, with angular distributions at numerous specific energies. Such presentations have limited visual appeal, and their physical content is typically extracted through some model- dependent treatment. Instead, we explore the use of a Legendre series expansion with a relatively small number of essential coefficients. This approach has been applied in several recent experimental investigations. We present some general properties of the Legendre coefficients in the helicity framework and consider what physical information can be extracted without any model-dependent assumptions.

   ↳ hep-phhep-exnucl-exnucl-thPRC(2017)·4 citations
4. 04*

   Large-area silica aerogel for use as Cherenkov radiators with high refractive index, developed by supercritical carbon dioxide drying

   Makoto Tabata🇯🇵 · Ichiro Adachi🇯🇵 · Yoshikiyo Hatakeyama🇯🇵 · Hideyuki Kawai🇯🇵 · Takeshi Morita🇯🇵 · Takayuki Sumiyoshi🇯🇵

   This study presents the development of large-area (18 $\times$ 18 $\times$ 2 cm${}^3$), high refractive index ($n\sim$1.05) hydrophobic silica aerogel tiles for use as Cherenkov radiators. These transparent aerogel tiles will be installed in a Cherenkov detector for the next-generation accelerator-based particle physics experiment Belle II, to be performed at the High Energy Accelerator Research Organization (KEK) in Japan. Cracking has been eliminated from the prototype aerogel tiles by improving the supercritical carbon dioxide (scCO${}_2$) extraction procedure when drying the wet gel tiles. Finally, a method of mass-producing aerogel tiles for the actual detector was established. It was confirmed that the experimentally manufactured aerogel tiles meet the required optical and hydrophobic characteristics and have a uniform tile density.

   ↳ physics.ins-dethep-exnucl-exThe Journal of Supercritical Fluids(2016)·7 citations
5. 05*

   Uncertainties in s-process nucleosynthesis in massive stars determined by Monte Carlo variations

   Nobuya Nishimura🇬🇧 · Raphael Hirschi · Thomas Rauscher🇬🇧 · Alexander St. J. Murphy🇬🇧 · Gabriele Cescutti

   The $s$-process in massive stars produces the weak component of the $s$-process (nuclei up to $A\sim 90$), in amounts that match solar abundances. For heavier isotopes, such as barium, production through neutron capture is significantly enhanced in very metal-poor stars with fast rotation. However, detailed theoretical predictions for the resulting final $s$-process abundances have important uncertainties caused both by the underlying uncertainties in the nuclear physics (principally neutron capture reaction and $\beta$-decay rates) as well as by the stellar evolution modeling. In this work, we investigated the impact of nuclear-physics uncertainties relevant to the $s$-process in massive stars. Using a Monte-Carlo based approach, we performed extensive nuclear reaction network calculations that include newly evaluated upper and lower limits for the individual temperature dependent reaction rates. We found that most of the uncertainty in the final abundances is caused by uncertainties in the neutron capture rates, while $\beta$-decay rate uncertainties affect only a few nuclei near $s$-process branchings. The $s$-process in rotating metal-poor stars shows quantitatively different uncertainties and key reactions, although the qualitative characteristics are similar. We confirmed that our results do not significantly change at different metallicities for fast rotating massive stars in the very low metallicity regime. We highlight which of the identified key reactions are realistic candidates for improved measurement by future experiments.

   ↳ astro-ph.SRnucl-exnucl-thMNRAS(2017)·42 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.