arXiv subjects

H. En'yo

Publications and source records attributed to H. En'yo.

114 records · Page 7Linked to original sources

arXiv2007

J/$ψ$ suppression in In-In collisions at 158 GeV/nucleon

The NA60 experiment has studied J/$ψ$ production in Indium-Indium collisions at 158 A$\cdot$GeV. In this paper we present an updated set of results obtained with the complete set of available statistics and an improved alignment of the vertex tracker. The centrality dependence of the J/$ψ$ production, obtained with an analysis technique based only on the J/$ψ$ sample, indicates that a suppression beyond that induced by nuclear absorption is present in In-In collisions, setting in at $\sim$80 participant nucleons. A first study of the systematic errors related with this measurement is discussed. We also present preliminary results on the J/$ψ$ azimuthal distributions.

nucl-ex↗

arXiv2006

Low Mass Dimuon Production in Indium-Indium Collisions at the CERN SPS

NA60 is a fixed-target experiment at the CERN SPS which measured dimuon production in nucleus-nucleus and proton-nucleus collisions. In this paper we report on a precision measurement of low-mass muon pairs in 158 AGeV indium-indium collisions. A significant excess of pairs is observed above the yield expected from neutral meson decays. The excess can be isolated by subtraction of expected sources, thanks to the excellent mass resolution and large sample size.

nucl-ex↗

arXiv2006

Nuclear mass number dependence of inclusive production of omega and phi mesons in 12 GeV p + A collisions

The inclusive production of omega and phi mesons is studied in the backward region of the interaction of 12 GeV protons with polyethylene, carbon, and copper targets. The mesons are measured in e^+ e^- decay channels. The production cross sections of the mesons are presented as functions of rapidity y and transverse momentum p_T. The nuclear mass number dependences (A dependences) are found to be A^{0.710 +/- 0.021(stat) +/- 0.037(syst)} for omega mesons and A^{0.937 +/- 0.049(stat) +/- 0.018(syst)} for phi mesons in the region of 0.9 < y < 1.7 and p_T < 0.75 GeV/c.

nucl-ex↗

arXiv2006

Experimental Signature of Medium Modifications for rho and omega Mesons in the 12 GeV p + A Reactions

The invariant mass spectra of e+e- pairs produced in 12-GeV proton-induced nuclear reactions are measured at the KEK Proton-Synchrotron. On the low-mass side of the omega meson peak, a significant enhancement over the known hadronic sources has been observed. The mass spectra, including the excess, are well reproduced by a model that takes into account the density dependence of the vector meson mass modification, as theoretically predicted.

nucl-ex↗

arXiv2005

Study of dimuon production in Indium-Indium collisions with the NA60 experiment

The NA60 experiment at the CERN-SPS is devoted to the study of dimuon production in heavy-ion and proton-nucleus collisions. We present preliminary results from the analysis of Indium-Indium collisions at 158 GeV per nucleon. The topics covered are low mass vector meson production, J/psi production and suppression, and the feasibility of the open charm measurement from the dimuon continuum in the mass range below the J/psi peak.

hep-ex↗

arXiv2000

Observation of $ρ/ ω$ Meson Modification in Nuclear Matter

We have measured invariant mass spectra of electron-positron pairs in the target rapidity region of 12GeV p+A reactions. We have observed a significant difference in the mass spectra below the $ω$ meson between p+C and p+Cu interactions. The difference is interpreted as a signature of the $ρ/ω$ modification at normal nuclear-matter density.

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