Observation of pi(+)pi(-)pi(+)pi(-) photoproduction in ultraperipheral heavy-ion collisions at root s(NN)=200 GeV at the STAR detector
Contribuinte(s) |
UNIVERSIDADE DE SÃO PAULO |
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Data(s) |
18/04/2012
18/04/2012
2010
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Resumo |
We present a measurement of pi(+)pi(-)pi(+)pi(-) photonuclear production in ultraperipheral Au-Au collisions at root s(NN) = 200 GeV from the STAR experiment. The pi(+)pi(-)pi(+)pi(-) final states are observed at low transverse momentum and are accompanied by mutual nuclear excitation of the beam particles. The strong enhancement of the production cross section at low transverse momentum is consistent with coherent photoproduction. The pi(+)pi(-)pi(+)pi(-) invariant mass spectrum of the coherent events exhibits a broad peak around 1540 +/- 40 MeV/c(2) with a width of 570 +/- 60 MeV/c(2), in agreement with the photoproduction data for the rho(0)(1700). We do not observe a corresponding peak in the pi(+)pi(-) final state and measure an upper limit for the ratio of the branching fractions of the rho(0)(1700) to pi(+)pi(-) and pi(+)pi(-)pi(+)pi(-) of 2.5% at 90% confidence level. The ratio of rho(0)(1700) and rho(0)(770) coherent production cross sections is measured to be 13.4 +/- 0.8(stat.) +/- 4.4(syst.)%. US DOE Office of Science US NSF National Science Foundation Sloan Foundation Deutsche Forschungsgemeinschaft - DFG Centre National de la Recherche Scientifique - CNRS[CNRS/IN2P3] STFC EPSRC of the United Kingdom FAPESP CNPq of Brazil MES Ministry of Education and Science of the Russian Federation National Natural Science Foundation of China (NNSFC) CAS of China MoST of China MoE of China GACR Czech Republic FOM and NWO of the Netherlands (DAE) Department of Atomic Energy, India (CSIR) Council of Scientific and Industrial Research - India Polish Ministry of Science and Higher Education Korea Research Foundation (KRF) Ministry of Science, Education, and Sports of the Republic of Croatia MES Russian Ministry of Science and Technology and RosAtom of Russia |
Identificador |
PHYSICAL REVIEW C, v.81, n.4, 2010 0556-2813 http://producao.usp.br/handle/BDPI/16304 10.1103/PhysRevC.81.044901 |
Idioma(s) |
eng |
Publicador |
AMER PHYSICAL SOC |
Relação |
Physical Review C |
Direitos |
restrictedAccess Copyright AMER PHYSICAL SOC |
Palavras-Chave | #HELICITY-COUPLING AMPLITUDES #TIME PROJECTION CHAMBER #GAMMA-GAMMA #PHOTON #PHYSICS #MASS #QUARKONIA #Physics, Nuclear |
Tipo |
article original article publishedVersion |