Multi-strange baryon production in p-Pb collisions at $\sqrt{s_\mathbf{NN}}=5.02$

J. Adam , H. Borel (1) , V.J.G. Feuillard (1, 2) , B. Hippolyte (3) , C. Kuhn (3) , A. Maire (3) , L. Molnar (3, 4) , C. Roy (3) , Laurent Aphecetche (4) , B. Audurier (4) , Guillaume Batigne (4) , B. Erazmus (4) , Magali Estienne (4) , Marie Germain (4) , J. Martin Blanco (4) , Gines Martinez Garcia (4) , L. Massacrier (4) , D.A. Moreira De Godoy (4) , A. Morreale (4) , Philippe Pillot (4) , L. Ronflette (4) , Y. Schutz (4) , Alexandre Shabetai (4) , Diego Stocco (4) , M. Wang (4) , J. Zhu (4) , C. Cheshkov (5) , B. Cheynis (5) , L. Ducroux (5) , J.-Y. Grossiord (5) , B. Teyssier (5) , R. Tieulent (5) , A. Uras (5) , R. Vernet (6) , G. Conesa Balbastre (7) , J. Faivre (7) , C. Furget (7) , R. Guernane (7) , C. Silvestre (7) , A. Vauthier (7) , Z. Conesa Del Valle (8) , I. Das (8) , B. Espagnon (8) , C. Hadjidakis (8) , I. Lakomov (8) , C. Suire (8) , J. D. Tapia Takaki (8) , M. Tarhini (8) , L. Valencia Palomo (8, 2) , V. Barret (2) , N. Bastid (2) , A. Batista Camejo (2) , P. Crochet (2) , P. Dupieux (2) , S. Li (2) , X. Lopez (2) , F. Manso (2) , S. Porteboeuf-Houssais (2) , P. Rosnet (2) , B. Vulpescu (2)

1 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
2 LPC - Laboratoire de Physique Corpusculaire - Clermont-Ferrand
3 IPHC - Institut Pluridisciplinaire Hubert Curien
4 SUBATECH - Laboratoire SUBATECH Nantes
5 IPNL - Institut de Physique Nucléaire de Lyon
6 CC-IN2P3 - Centre de Calcul de l'IN2P3
7 LPSC - Laboratoire de Physique Subatomique et de Cosmologie
8 IPNO - Institut de Physique Nucléaire d'Orsay

The multi-strange baryon yields in Pb--Pb collisions have been shown to exhibit an enhancement relative to pp reactions. In this work, $\Xi$ and $\Omega$ production rates have been measured with the ALICE experiment as a function of transverse momentum, ${p_{\rm T}}$, in p-Pb collisions at a centre-of-mass energy of ${\sqrt{s_{\rm NN}}}$ = 5.02 TeV. The results cover the kinematic ranges 0.6 GeV/$c<{p_{\rm T}} <$7.2 GeV/$c$ and 0.8 GeV/$c<{p_{\rm T}}<$ 5 GeV/$c$, for $\Xi$ and $\Omega$ respectively, in the common rapidity interval -0.5 $<{y_{\rm CMS}}<$ 0. Multi-strange baryons have been identified by reconstructing their weak decays into charged particles. The ${p_{\rm T}}$ spectra are analysed as a function of event charged-particle multiplicity, which in p-Pb collisions ranges over one order of magnitude and lies between those observed in pp and Pb-Pb collisions. The measured ${p_{\rm T}}$ distributions are compared to the expectations from a Blast-Wave model. The parameters which describe the production of lighter hadron species also describe the hyperon spectra in high multiplicity p-Pb. The yield of hyperons relative to charged pions is studied and compared with results from pp and Pb-Pb collisions. A statistical model is employed, which describes the change in the ratios with volume using a canonical suppression mechanism, in which the small volume causes a species-dependent relative reduction of hadron production. The calculations, in which the magnitude of the effect depends on the strangeness content, show good qualitative agreement with the data.

Domaines: Physique Nucléaire Expérimentale [nucl-ex]; Physique des Hautes Energies - Expérience [hep-ex]

J. Adam, H. Borel, V.J.G. Feuillard, B. Hippolyte, C. Kuhn, et al.. Multi-strange baryon production in p-Pb collisions at $\sqrt{s_\mathbf{NN}}=5.02$. Physics Letters B, 2016, 758, pp.389-401. ⟨10.1016/j.physletb.2016.05.027⟩. ⟨in2p3-01249887⟩