Observation of pi{sup +}pi{sup -}pi{sup +}pi{sup -} photoproduction in ultraperipheral heavy-ion collisions at sq root(s{sub NN})=200 GeV at the STAR detector

Journal Article · Thu Apr 15 04:00:00 EDT 2010 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.81.044901· OSTI ID:21388952

Abelev, B I; Betts, R R; Evdokimov, O; Garcia-Solis, E J; Hofman, D J; Hollis, R S; Iordanova, A; Kauder, K; Suarez, M C ^[1]; Aggarwal, M M; Bhati, A K; Kumar, L; Pruthi, N K ^[2]; Ahammed, Z; Chattopadhyay, S; Dutta Mazumdar, M R; Ganti, M S; Ghosh, P; Mohanty, B; Mondal, M M ^[3]

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1. University of Illinois at Chicago, Chicago, Illinois 60607 (United States)
2. Panjab University, Chandigarh 160014 (India)
3. Variable Energy Cyclotron Centre, Kolkata 700064 (India)

We present a measurement of pi{sup +}pi{sup -}pi{sup +}pi{sup -} photonuclear production in ultraperipheral Au-Au collisions at sq root(s{sub N{sub N}})=200 GeV from the STAR experiment. The pi{sup +}pi{sup -}pi{sup +}pi{sup -} 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{sup +}pi{sup -}pi{sup +}pi{sup -} invariant mass spectrum of the coherent events exhibits a broad peak around 1540+-40 MeV/c{sup 2} with a width of 570+-60 MeV/c{sup 2}, in agreement with the photoproduction data for the rho{sup 0}(1700). We do not observe a corresponding peak in the pi{sup +}pi{sup -} final state and measure an upper limit for the ratio of the branching fractions of the rho{sup 0}(1700) to pi{sup +}pi{sup -} and pi{sup +}pi{sup -}pi{sup +}pi{sup -} of 2.5% at 90% confidence level. The ratio of rho{sup 0}(1700) and rho{sup 0}(770) coherent production cross sections is measured to be 13.4+-0.8{sub stat.}+-4.4{sub syst.}%.

• OSTI ID: 21388952
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 4 Vol. 81; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ATOM COLLISIONS
ATOM-ATOM COLLISIONS
BASIC INTERACTIONS
BEAMS
BOSONS
BRANCHING RATIO
COHERENT PRODUCTION
COLLISIONS
CROSS SECTIONS
DIMENSIONLESS NUMBERS
ELECTROMAGNETIC INTERACTIONS
ELEMENTARY PARTICLES
ELEMENTS
ENERGY RANGE
ENERGY-LEVEL TRANSITIONS
EXCITATION
GEV RANGE
GEV RANGE 100-1000
GOLD
HADRONS
HEAVY ION REACTIONS
INTERACTIONS
LINEAR MOMENTUM
MASS SPECTRA
MESONS
METALS
NUCLEAR REACTIONS
PARTICLE INTERACTIONS
PARTICLE PRODUCTION
PHOTOPRODUCTION
PIONS
PIONS MINUS
PIONS PLUS
PSEUDOSCALAR MESONS
SPECTRA
TRANSITION ELEMENTS
TRANSVERSE MOMENTUM