Mon·Oct 27, 2014Monday·October 27, 2014

1. 01*

   Estimate of cold nuclear matter effects on bottom production in d+Au collisions at $\sqrt{s_{NN}}=200$ GeV

   Daniel Kikola🇵🇱 · Andrzej Lipiec🇵🇱

   We investigate modification of the bottom quark production due to cold nuclear matter effects (CNM) at mid-rapidity in d+Au collisions at $\sqrt{s_{NN}}=200$ GeV at RHIC. Our results indicate that bottom production is not suppressed due to CNM effects in those collisions. We also found that shadowing and initial $k_T$ breadboarding for charm quarks explains at low $p_T$ ($p_T<3$ GeV/c) the enhancement of heavy flavor decay electron yield in d+Au collisions at $\sqrt{s_{NN}}=200$ GeV compared to p+p.

   nucl-exActa Phys.Polon.B(2016)·2 citations
2. 02*

   Is the X(3915) the chi_{c0}(2P)?

   Stephen Lars Olsen🇰🇷

   The Particle Data Group has assigned the X(3915) meson, an omega J/psi mass peak seen in B-> omega J/psi decays and in two-photon fusion reactions gamma-gamma->omega J/psi, as the chi_{c0}(2P), the 2^3P_0 charmonium state. Here it is shown that if the X(3915) is the chi_{c0}(2P), the measured strength of the gamma-gamma->X(3915) signal implies an upper limit on the branching fraction Bf(chi_{c0}(2P)->omega J/psi)<7.8% that conflicts with a >14.3% lower limit derived for the same quantity from the B-> K X(3915) decay rate. Also, the absence any signal for X(3915)-> D0 D0-bar in B+ -> K+ D0 D0-bar decays is used to establish the limit Bf(X(3915)->D0 D0-bar) < 1.2xBf(X(3915)->omega J/psi). This contradicts expectations that chi_{c0}(2P) decays to D0 D0-bar would be a dominant process, while decays to omega J/psi, which are Okubo-Zweig-Iizuka suppressed, would be relatively rare. These, plus reasons given earlier by Guo and Meissner, raise serious doubts about the X(3915)=chi_{c0}(2P) assignment.

   ↳ hep-exhep-phnucl-exPRD(2015)·88 citations
3. 03*

   The effect of uu diquark suppression in proton splitting in Monte Carlo event generators

   V. Uzhinsky🇷🇺 · A. Galoyan🇷🇺

   Monte Carlo event generators assume that protons split into (uu)-diquarks and d-quarks with a probability of 1/3 in strong interactions. It is shown in this paper that using a value of 1/6 for the probability allows one to describe at a semi-quantitative level the NA49 Collaboration data for $p+p\to p+X$ reactions at 158 GeV/c. The Fritiof (FTF) model of Geant4 was used to simulate the reactions. The reduced weight of the (uu)-diquarks in protons is expected in the instanton model.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2015)·3 citations
4. 04*

   Longitudinal target-spin asymmetries for deeply virtual Compton scattering

   E. Seder · A. Biselli · S. Pisano · S. Niccolai · the CLAS Collaboration

   A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6-GeV electron beam, a longitudinally polarized proton target and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for $ep\to e^{\prime }{p}^{\prime }\gamma$ events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in $Q^2$, $x_B$, $t$ and $\varphi$, for 166 four-dimensional bins. In the framework of Generalized Parton Distributions (GPDs), at leading twist the $t$ dependence of these asymmetries provides insight on the spatial distribution of the axial charge of the proton, which appears to be concentrated in its center. These results also bring important and necessary constraints for the existing parametrizations of chiral-even GPDs.

   ↳ hep-exnucl-exPRL(2015)·67 citations
5. 05*

   Backgrounds and sensitivity of the NEXT double beta decay experiment

   M. Nebot-Guinot🇪🇸 · P. Ferrario🇪🇸 · J. Martin-Albo🇪🇸 · J. Muñoz Vidal🇪🇸 · J.J. Gómez-Cadenas (for the NEXT Collaboration)🇪🇸

   NEXT (Neutrino Experiment with a Xenon TPC) is a neutrinoless double-beta (\beta \beta 0\nu) decay experiment that will operate at the Canfranc Underground Laboratory (LSC). It is an electroluminescent high-pressure gaseous xenon Time Projection Chamber (TPC) with separate read-out planes for calorimetry and tracking. Energy resolution and background suppression are the two key features of any neutrinoless double beta decay experiment. NEXT has both good energy resolution (<1% FWHM) at the Q value of ${}^{136}$Xe and an extra handle for background identification provided by track reconstruction. With the background model of NEXT, based on the detector simulation and the evaluation of the detector radiopurity, we can determine the sensitivity to a measurement of the \beta\beta 2\nu\ mode in NEW and to a \beta\beta 0\nu\ search in NEXT100. In this way we can predict the background rate of $5\times 10^{-4}$counts/(keV kg yr), and a sensitivity to the Majorana neutrino mass down to 100 meV after a 5-years run of NEXT100.

   ↳ physics.ins-dethep-exnucl-exNucl.Part.Phys.Proc.(2016)·4 citations
6. 06*

   Latest results of NEXT-DEMO, the prototype of the NEXT 100 double beta decay experiment

   L. Serra🇪🇸 · D. Lorca🇪🇸 · J. Martin-Albo🇪🇸 · M. Sorel🇪🇸 · J. J. Gomez-Cadenas (for the NEXT Collaboration)🇪🇸

   NEXT-DEMO is a 1:4.5 scale prototype of the NEXT100 detector, a high-pressure xenon gas TPC that will search for the neutrinoless double beta decay of ${}^{136}$Xe. X-ray energy depositions produced by the de-excitation of Xenon atoms after the interaction of gamma rays from radioactive sources have been used to characterize the response of the detector obtaining the spatial calibration needed for close-to-optimal energy resolution. Our result, 5.5% FWHM at 30 keV, extrapolates to 0.6% FWHM at the Q value of ${}^{136}$Xe. Additionally, alpha decays from radon have been used to measure several detection properties and parameters of xenon gas such as electron-ion recombination, electron drift velocity, diffusion and primary scintillation light yield. Alpha spectroscopy is also used to quantify the activity of radon inside the detector, a potential source of background for most double beta decay experiments.

   ↳ physics.ins-dethep-exnucl-ex6 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.