Fri·Oct 30, 2015Friday·October 30, 2015

1. 01*

   Latest results from the NA61/SHINE beam energy scan with p+p and Be+Be collisions

   Maja Mackowiak-Pawlowska (for the NA61/SHINE Collaboration)🇵🇱

   The NA61/SHINE experiment aims to discover the critical point of strongly interacting matter and study the properties of the onset of deconfinement by measurements of hadron production properties in proton-proton, proton-nucleus and nucleus-nucleus interactions in the CERN SPS energy range. This contribution presents results on the energy dependence of hadron spectra and yields as well as on fluctuations and two-particle correlations in p+p and centrality selected Be+Be collisions. In particular, the energy dependence of the signal of deconfinement, the "horn", observed in central Pb+Pb collisions is compared with the corresponding results from p+p interactions. Also string-hadronic models are tested using hadron spectra and fluctuations measured in p+p interactions. Results on fluctuations (multiplicity and transverse momentum) are presented as a function of the collision energy for Be+Be and p+p collisions in search for the critical point of strongly interacting matter.

   nucl-exPoS EPS-HEP2015 (2015) 205·1 citation
2. 02*

   Centrality Dependence of Particle Production in p-A collisions measured by ALICE

   Alberica Toia (for the ALICE Collaboration)🇩🇪

   We present the centrality dependence of particle production in p-Pb collisions at sqrt(s_NN)= 5.02 TeV measured by the ALICE experiment, including the pseudo-rapidity and transverse momentum spectra, with a special emphasis on the event classification in centrality classes and its implications for the interpretation of the nuclear effects.

   nucl-exJ.Phys.Conf.Ser.(2016)·0 citations
3. 03*

   Particle production in p-Pb collisions with ALICE at the LHC

   Alberica Toia (for the ALICE Collaboration)🇩🇪

   Measurements of the transverse momentum spectra of light flavor particles at intermediate and high pT are an important tool for QCD studies. In pp collisions they provide a baseline for perturbative QCD, while in Pb-Pb they are used to investigate the suppression caused by the surrounding medium. In p-Pb collisions, such measurements provide a reference to disentangle final from initial state effects and thus play an important role in the search for signatures of the formation of a deconfined hot medium. While the comparison of the p-Pb and Pb-Pb data indicates that initial state effects do not play a role in the suppression of hadron production observed at high pT in heavy ion collisions, several measurements of particle production in the low and intermediate pT region indicate the presence of collective effects.

   nucl-exEPJ Web Conf.(2016)·0 citations
4. 04*

   Opportunities With Decay-At-Rest Neutrinos From Decay-In-Flight Neutrino Beams

   C. Grant🇺🇸 · B. R. Littlejohn🇺🇸

   Neutrino beam facilities, like spallation neutron facilities, produce copious quantities of neutrinos from the decay at rest of mesons and muons. The viability of decay-in-flight neutrino beams as sites for decay-at-rest neutrino studies has been investigated by calculating expected low-energy neutrino fluxes from the existing Fermilab NuMI beam facility. Decay-at-rest neutrino production in NuMI is found to be roughly equivalent per megawatt to that of spallation facilities, and is concentrated in the facility's target hall and beam stop regions. Interaction rates in 5 and 60 ton liquid argon detectors at a variety of existing and hypothetical locations along the beamline are found to be comparable to the largest existing decay-at-rest datasets for some channels. The physics implications and experimental challenges of such a measurement are discussed, along with prospects for measurements at targeted facilities along a future Fermilab long-baseline neutrino beam.

   ↳ hep-exhep-phnucl-exphysics.ins-detPoS(2016)·14 citations
5. 05*

   Compositeness of the Delta(1232) resonance in pi N scattering

   Takayasu Sekihara (Osaka U., Res. Ctr. Nucl. Phys.)🇯🇵 · Takashi Arai (KEK, Tsukuba)🇯🇵 · Junko Yamagata-Sekihara (Nat. Inst. Tech., Oshima Coll.)🇯🇵 · Shigehiro Yasui (Tokyo Inst. Tech.)🇯🇵

   We evaluate the $\pi N$ compositeness of the $\Delta (1232)$ resonance so as to clarify the internal structure of $\Delta (1232)$ in terms of the $\pi N$ component. Here the compositeness is defined as contributions from two-body wave functions to the normalization of the total wave function and is extracted from the $\pi N$ scattering amplitude. In this study we employ the chiral unitary approach with the interaction up to the next-to-leading order plus a bare $\Delta$ term in chiral perturbation theory and describe $\Delta (1232)$ in an elastic $\pi N$ scattering. Fitting the $\pi N$ scattering amplitude to the solution of the partial wave analysis, we obtain a large real part of the $\pi N$ compositeness for $\Delta (1232)$ comparable to unity and non-negligible imaginary part as well, with which we reconfirm the result in the previous study on the $\pi N$ compositeness for $\Delta (1232)$.

   ↳ hep-phhep-exnucl-exnucl-thJPS Conf.Proc.(2016)·2 citations
6. 06*

   Pentaquark states in a diquark-triquark model

   Ruilin Zhu🇨🇳 · Cong-Feng Qiao🇨🇳

   The diquark-triquark model is used to explain charmonium-pentaquark states, i.e., $P_c(4380)$ and $P_c(4450)$, which were observed recently by the LHCb collaboration. For the first time, we investigate the properties of the color attractive configuration of a triquark and we define a nonlocal light cone distribution amplitude for pentaquark states, where both diquark and triquark are not pointlike, but they have nonzero size. We establish an effective diquark-triquark Hamiltonian based on spin-orbital interaction. According to the Hamiltonian, we show that the minimum mass splitting between ${\frac{5}{2}}^{+}$ and ${\frac{3}{2}}^{-}$ is around $100$~MeV, which may naturally solve the challenging problem of small mass splitting between $P_c(4450)$ and $P_c(4380)$. This helps to understand the peculiarities of $P_c(4380)$ with a broad decay width whereas $P_c(4450)$ has a narrow decay width. Based on the diquark-triquark model, we predict more pentaquark states, which will hopefully be measured in future experiments.

   ↳ hep-phhep-exnucl-exPLB(2016)·169 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.