Wed·Sep 10, 2014Wednesday·September 10, 2014

1. 01*

   Measurement of the $np\to np{\pi }^0{\pi }^0$ Reaction in Search for the Recently Observed $d^{\ast }(2380)$ Resonance

   P. Adlarson🇸🇪 · W. Augustyniak🇵🇱 · W. Bardan🇵🇱 · M. Bashkanov🇩🇪 · F. S. Bergmann🇩🇪 · M. Berłowski🇵🇱 · H. Bhatt🇮🇳 · A. Bondar🇷🇺 · M. Büscher🇩🇪 · H. Calén🇸🇪 · I. Ciepał🇵🇱 · H. Clement🇩🇪 and 90 other authors

   Exclusive measurements of the quasi-free $np\to np{\pi }^0{\pi }^0$ reaction have been performed by means of $dp$ collisions at $T_d$ = 2.27 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region $\sqrt{s}$ = (2.35 - 2.46) GeV, which includes the region of the ABC effect and its associated $d^{\ast }(2380)$ resonance. Adding the $d^{\ast }$ resonance amplitude to that for the conventional processes leads to a reasonable description of the data. The observed resonance effect in the total cross section is in agreement with the predictions of Fäldt and Wilkin as well Albadajedo and Oset. The ABC effect, {\it i.e.} the low-mass enhancement in the ${\pi }^0{\pi }^0$-invariant mass spectrum, is found to be very modest - if present at all, which might pose a problem to some of its interpretations.

   nucl-exPLB(2015)·105 citations
2. 02*

   Search for double beta decay of ${}^{136}$Ce and ${}^{138}$Ce with HPGe gamma detector

   P. Belli (1)🇮🇹 · R. Bernabei (1,2)🇮🇹 · R. S. Boiko (3)🇺🇦 · F. Cappella (4,5)🇮🇹 · R. Cerulli (6)🇮🇹 · F. A. Danevich (3)🇺🇦 · A. Incicchitti (4,5)🇮🇹 · B. N. Kropivyansky (3)🇺🇦 · M. Laubenstein (6)🇮🇹 · D. V. Poda (3)🇺🇦 · O. G. Polischuk (3,4)🇺🇦 · V. I. Tretyak (3,4) ((1) INFN Roma Tor Vergata, (2) Univ. Roma Tor Vergata, (3) INR Kiev, (4) INFN Roma, (5) Univ. Roma, (6) INFN LNGS)🇺🇦

   Search for double $\beta$ decay of ${}^{136}$Ce and ${}^{138}$Ce was realized with 732 g of deeply purified cerium oxide sample measured over 1900 h with the help of an ultra-low background HPGe $\gamma$ detector with a volume of 465 cm${}^3$ at the STELLA facility of the Gran Sasso National Laboratories of the INFN (Italy). New improved half-life limits on double beta processes in the cerium isotopes were set at the level of $\lim T_{1/2}\sim 10^{17}-10^{18}$~yr; many of them are even two orders of magnitude larger than the best previous results.

   nucl-exphysics.ins-detNPA(2014)·20 citations
3. 03*

   Multiple scattering effects on heavy meson production in p+A collisions at backward rapidity

   Zhong-Bo Kang🇺🇸 · Ivan Vitev🇺🇸 · Enke Wang🇨🇳 · Hongxi Xing🇺🇸 · Cheng Zhang🇨🇳

   We study the incoherent multiple scattering effects on heavy meson production in the backward rapidity region of p+A collisions within the generalized high-twist factorization formalism. We calculate explicitly the double scattering contributions to the heavy meson differential cross sections by taking into account both initial-state and final-state interactions, and find that these corrections are positive. We further evaluate the nuclear modification factor for muons that come form the semi-leptonic decays of heavy flavor mesons. Phenomenological applications in d+Au collisions at a center-of-mass energy $\sqrt{s}=200$ GeV at RHIC and in p+Pb collisions at $\sqrt{s}=5.02$ TeV at the LHC are presented. We find that incoherent multiple scattering can describe rather well the observed nuclear enhancement in the intermediate $p_T$ region for such reactions.

   ↳ hep-phhep-exnucl-exnucl-thPLB(2015)·92 citations
4. 04*

   Deconfinement as an entropic self-destruction: a solution for the quarkonium suppression puzzle?

   Dmitri E. Kharzeev🇺🇸

   The entropic approach to dissociation of bound states immersed in strongly coupled systems is developed. In such systems, the excitations of the bound state are often delocalized and characterized by a large entropy, so that the bound state is strongly entangled with the rest of the statistical system. If this entropy $S$ increases with the separation $r$ between the constituents of the bound state, $S=S(r)$, then the resulting entropic force $F=T\partial S/\partial r$ ($T$ is temperature) can drive the dissociation process. As a specific example, we consider the case of heavy quarkonium in strongly coupled quark-gluon plasma, where lattice QCD indicates a large amount of entropy associated with the heavy quark pair at temperatures $0.9T_c\le T\le 1.5T_c$ ($T_c$ is the deconfinement temperature); this entropy $S(r)$ grows with the inter-quark distance $r$. We argue that the entropic mechanism results in an anomalously strong quarkonium suppression in the temperature range near $T_c$. This "entropic self-destruction" may thus explain why the experimentally measured quarkonium nuclear modification factor at RHIC (lower energy density) is smaller than at LHC (higher energy density), possibly resolving the "quarkonium suppression puzzle" - all of the previously known mechanisms of quarkonium dissociation operate more effectively at higher energy densities, and this contradicts the data. Moreover, we find that near $T_c$ the entropic force leads to delocalization of the bound hadron states; we argue that this delocalization may be the mechanism underlying deconfinement.

   ↳ hep-phhep-thnucl-exnucl-thPRD(2014)·53 citations
5. 05*

   Investigation of Hamamatsu H8500 phototubes as single photon detectors

   M. Hoek🇩🇪 · V. Lucherini🇮🇹 · M. Mirazita🇮🇹 · R.A. Montgomery🇮🇹 · A. Orlandi🇮🇹 · S. Anefalos Pereira🇮🇹 · S. Pisano🇮🇹 · P. Rossi🇺🇸 · A. Viticchiè🇮🇹 · A. Witchger🇺🇸

   We have investigated the response of a significant sample of Hamamatsu H8500 MultiAnode PhotoMultiplier Tubes (MAPMTs) as single photon detectors, in view of their use in a ring imaging Cherenkov counter for the CLAS12 spectrometer at the Thomas Jefferson National Accelerator Facility. For this, a laser working at 407.2nm wavelength was employed. The sample is divided equally into standard window type, with a spectral response in the visible light region, and UV-enhanced window type MAPMTs. The studies confirm the suitability of these MAPMTs for single photon detection in such a Cherenkov imaging application.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2015)·14 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.