Mon·Jan 19, 2015Monday·January 19, 2015

1. 01*

   Resonances as Probes of Heavy-Ion Collisions at ALICE

   A. G. Knospe (for the ALICE Collaboration)🇺🇸

   Hadronic resonances serve as unique probes in the study of the hot and dense nuclear matter produced in heavy-ion collisions. Properties of the hadronic phase of the collision can be extracted from measurements of the suppression of resonance yields. A comparison of the transverse-momentum spectra of the phi(1020) meson and the proton (which have similar masses) can be used to study particle production mechanisms. Resonance measurements in pp collisions provide input for tuning QCD-inspired particle production models and serve as reference measurements for other collision systems. Measurements of resonances in p-Pb collisions allow nuclear effects in the absence of a hot and dense final state to be studied. The ALICE Collaboration has measured resonances in pp, p-Pb, and Pb-Pb collisions. These measurements will be discussed and compared to results from other experiments and to theoretical models.

   nucl-exJ.Phys.Conf.Ser.(2015)·6 citations
2. 02*

   Subthreshold Xi- Production in Collisions of p(3.5 GeV)+Nb

   G. Agakishiev · O. Arnold · A. Balanda · D. Belver · A.V. Belyaev · J.C. Berger-Chen · A. Blanco · M. Böhmer · J.L. Boyard · P. Cabanelas · S. Chernenko · A. Dybczak and 86 other authors

   Results on the production of the double-strange cascade hyperon ${\mathrm{\Xi }}^{-}$ are reported for collisions of p\,(3.5~GeV)\,+\,Nb, studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18 at GSI Helmholtzzentrum for Heavy-Ion Research, Darmstadt. For the first time, subthreshold ${\mathrm{\Xi }}^{-}$ production is observed in proton-nucleus interactions. Assuming a ${\mathrm{\Xi }}^{-}$ phase-space distribution similar to that of $\mathrm{\Lambda }$ hyperons, the production probability amounts to $P_{{\mathrm{\Xi }}^{-}}=(2.0\pm 0.4(\mathrm{stat})\pm 0.3(\mathrm{norm})\pm 0.6(\mathrm{syst}))\times 10^{-4}$ resulting in a ${\mathrm{\Xi }}^{-}/(\mathrm{\Lambda }+{\mathrm{\Sigma }}^0)$ ratio of $P_{{\mathrm{\Xi }}^{-}}/P_{\mathrm{\Lambda }+{\mathrm{\Sigma }}^0}=(1.2\pm 0.3(\mathrm{stat})\pm 0.4(\mathrm{syst}))\times 10^{-2}$. Available model predictions are significantly lower than the estimated ${\mathrm{\Xi }}^{-}$ yield.

   nucl-exPRL(2015)·45 citations
3. 03*

   Comments on "Interference phenomena in the $J^p=1/2^{-}$ - wave in $\eta$ photoproduction" by A.V. Anisovich et al. [arXiv:1501.02093]

   Viacheslav Kuznetsov🇷🇺

   The authors of arXiv:1501.02093v1 claimed that " ... narrow structure observed in the excitation function of $\gamma n\to \eta n$ can be reproduced fully with a particular interference pattern in the $J^p=1/2^{-}$ partial wave..." while a narrow structure in Compton scattering off the neutron is "...a stand-alone observation unrelated to the structure observed in $\gamma n\to \eta n$...". The source for the second statement may be a simple numerical error. If so, the interpretation of the narrow structure in $\gamma n\to \eta n$ as interference effects in the $J^p=1/2^{-}$-wave and some conclusions from arXiv:1501.02093v1 are questionable.

   nucl-exhep-exhep-ph0 citations
4. 04*

   Possible observables for the chiral electric separation effect in Cu + Au collisions

   Guo-Liang Ma🇨🇳 · Xu-Guang Huang🇨🇳

   The quark-gluon plasma (QGP) generated in relativistic heavy-ion collisions could be locally parity-odd. In parity-odd QGP, the electric field may induce a chiral current which is called the chiral electric separation effect (CESE). We propose two possible observables for CESE in Cu + Au collisions: The first one is the correlation ${\zeta }_{\alpha \beta }=⟨\cos [2({\varphi }_{\alpha }+{\varphi }_{\beta }-2{\Psi }_{\mathrm{RP}})]⟩$; the second one is the charge-dependent event-plane angle ${\Psi }_2^q$ with $q=\pm$ being charge. Nonzero $\Delta \zeta ={\zeta }_{opp}-{\zeta }_{same}$ and $\Delta \Psi =⟨|{\Psi }_2^{+}-{\Psi }_2^{-}|⟩$ may signal the CESE in Cu + Au collisions. Within a multiphase transport model, we study how the final state interaction affects these observables. We find that the correlation ${\gamma }_{\alpha \beta }=⟨\cos ({\varphi }_{\alpha }+{\varphi }_{\beta }-{\Psi }_{\mathrm{RP}})⟩$ is sensitive to the out-of-plane charge separation caused by the chiral magnetic effect and to the in-plane charge separation caused by the in-plane electric field, but it is not sensitive to the CESE. On the other hand, $\Delta \zeta$ and $\Delta \Psi$ are sensitive to the CESE. Therefore, we suggest that the future experiments measure the above observables in Cu+Au collisions in order to disentangle different chiral and charge separation mechanisms.

   ↳ nucl-thhep-phnucl-exPRC(2015)·19 citations
5. 05*

   Constraining the Eq. of State of Super-Hadronic Matter from Heavy-Ion Collisions

   Scott Pratt🇺🇸 · Evan Sangaline🇺🇸 · Paul Sorensen🇺🇸 · Hui Wang🇺🇸

   The equation of state of QCD matter for temperatures near and above the quark-hadron transition (165 MeV) is inferred within a Bayesian framework through the comparison of data from the Relativistic Heavy Ion Collider and from the Large Hadron Collider to theoretical models. State-of- the-art statistical techniques are applied to simultaneously analyze multiple classes of observables while varying 14 independent model parameters. The resulting posterior distribution over possible equations of state is consistent with results from lattice gauge theory.

   ↳ nucl-thnucl-exPRL(2015)·228 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.