Fri·Jan 6, 2017Friday·January 6, 2017

1. 01*

   Measurements of minimum entropy at K-shell photoelectric effect provides the radius and shape of the proton

   Jimenez Edward · Recalde Nicolas · Jimenez Esteban

   Constructive resonances with minimum entropy are derived from measurements of photoelectric effect cross sections at atomic K-shell thresholds. A resonance region with optimal constructive interference is given by a principal wave length {\lambda} of the order of Bohr atom radius. Our study shows that the proton shape is not a sphere but it has an elliptical volumetric shape with two equal axes and the other different. Resonance waves allowed us the possibility to measure both proton radius and shape through an interference term. This last, was a necessary condition in order to have an effective cross section maximum at threshold. The minimum entropy means minimum shape deformation and it was found to be (0.830 +/- 0.015) fm and the average proton radius was found to be (0.851 +/- 0.201) fm.

   nucl-ex0 citations
2. 02*

   Parton saturation scaling function for exclusive production of vector mesons and Deeply Virtual Compton Scattering

   F.G. Ben🇧🇷 · M.V.T. Machado🇧🇷 · W.K. Sauter🇧🇷

   We provide a universal expression of cross sections for the exclusive vector meson production and Deeply Virtual Compton Scattering (DVCS) in photon-proton and photon-nucleus interactions based on the geometric scaling phenomenon. The theoretical parameterization based on the scaling property depends only on the single variable ${\tau }_A=Q^2/Q_{\mathrm{sat}}^2$, where the saturation scale, $Q_{\mathrm{sat}}$, drives the energy dependence and the corresponding nuclear effects. This phenomenological result describes all available data from DESY-HERA for $\rho ,\varphi ,J/\psi$ production and DVCS measurements. A discussion on the size of nuclear shadowing corrections on photon-nucleus interaction is also done.

   ↳ hep-phhep-exnucl-exPRD(2017)·18 citations
3. 03*

   Measurements of $B\to J/\psi$ at forward rapidity in $p$$+$$p$ collisions at $\sqrt{s}=510$ GeV

   C. Aidala · N.N. Ajitanand · Y. Akiba · R. Akimoto · J. Alexander · M. Alfred · K. Aoki · N. Apadula · H. Asano · E.T. Atomssa · A. Attila · T.C. Awes and 420 other authors

   We report the first measurement of the fraction of $J/\psi$ mesons coming from $B$-meson decay ($F_{B\to J/\psi }$) in $p$+$p$ collisions at $\sqrt{s}=$ 510 GeV. The measurement is performed using the forward silicon vertex detector and central vertex detector at PHENIX, which provide precise tracking and distance-of-closest-approach determinations, enabling the statistical separation of $J/\psi$ due to $B$-meson decays from prompt $J/\psi$. The measured value of $F_{B\to J/\psi }$ is 8.1\%$\pm$2.3\% (stat)$\pm$1.9\% (syst) for $J/\psi$ with transverse momenta $0<p_T<5$ GeV/$c$ and rapidity $1.2<|y|<2.2$. The measured fraction $F_{B\to J/\psi }$ at PHENIX is compared to values measured by other experiments at higher center of mass energies and to fixed-order-next-to-leading-logarithm and color-evaporation-model predictions. The $b\bar{b}$ cross section per unit rapidity ($d\sigma /dy(pp\to b\bar{b})$) extracted from the obtained $F_{B\to J/\psi }$ and the PHENIX inclusive $J/\psi$ cross section measured at 200 GeV scaled with color-evaporation-model calculations, at the mean $B$ hadron rapidity $y=\pm 1.7$ in 510 GeV $p$$+$$p$ collisions, is $3.63_{-1.70}^{+1.92}\mu$b, and it is consistent with the fixed-order-next-to-leading-logarithm calculations.

   ↳ hep-exnucl-exPRD(2017)·17 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.