Fri·Jan 27, 2017Friday·January 27, 2017

1. 01*

   Direct photon yield in pp and in Pb-Pb collisions measured with the ALICE experiment

   Davide Francesco Lodato (for the ALICE Collaboration)🇳🇱

   The measurement of direct photon production in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV and in pp collisions at $\sqrt{s}=7$ TeV with the ALICE experiment is presented. In Pb-Pb collisions a clear direct photon signal below 3 GeV/$c$ is observed only for the $0-20\text{mbox}\%$ most central collisions. No excess is observed for semi-central and peripheral Pb-Pb collisions and in pp collisions. Furthermore, in pp collision the measurement of direct photon production in the range 10 $\le p_{\mathrm{T}}\le$ 60 GeV/$c$ is reported. The analysis is performed on the EMCal-triggered data taken in $2011$. The two main sources of background, namely photons from fragmentation processes and decay photons, have been subtracted from the inclusive photon spectrum by means of an isolation technique combined with the study of the transverse dispersion of electromagnetic showers. The measurement is in agreement both with NLO pQCD calculations and with those performed by the ATLAS and the CMS collaborations, extending the isolated photon spectrum investigated at LHC towards lower values of $p_{\mathrm{T}}$.

   nucl-exNucl.Part.Phys.Proc.(2017)·0 citations
2. 02*

   Production of $\Sigma (1385{)}^{\pm }$ and $\Xi (1530{)}^0$ in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

   ALICE Collaboration

   The transverse momentum distributions of the strange and double-strange hyperon resonances ($\Sigma (1385{)}^{\pm }$, $\Xi (1530{)}^0$) produced in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV were measured in the rapidity range $-0.5<y_{\mathrm{CMS}}<0$ for event classes corresponding to different charged-particle multiplicity densities, $⟨\mathrm{d}{N}_{\mathrm{ch}}/\mathrm{d}{\eta }_{\mathrm{lab}}⟩$. The mean transverse momentum values are presented as a function of $⟨\mathrm{d}{N}_{\mathrm{ch}}/\mathrm{d}{\eta }_{\mathrm{lab}}⟩$, as well as a function of the particle masses and compared with previous results on hyperon production. The integrated yield ratios of excited to ground-state hyperons are constant as a function of $⟨\mathrm{d}{N}_{\mathrm{ch}}/\mathrm{d}{\eta }_{\mathrm{lab}}⟩$. The equivalent ratios to pions exhibit an increase with $⟨\mathrm{d}{N}_{\mathrm{ch}}/\mathrm{d}{\eta }_{\mathrm{lab}}⟩$, depending on their strangeness content.

   nucl-exhep-exEPJC(2017)·65 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.