Observation of π+π−π+π− photoproduction in ultraperipheral heavy-ion collisions at √sNN=200 GeV at the STAR detector

Scientific paper - Original scientific paper

• Author: B. I. Abelev
• Author: ...
• Author: Mirko Planinić
• Author: ...
• Author: Nikola Poljak
• Author: ...
• Author: Y. Zoulkarneeva
• Collaboration: STAR Collaboration
• Author's institution: University of Zagreb; Faculty of Science; (Department of Physics)
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract (english)

We present a measurement of π+π−π+π− photonuclear production in ultraperipheral Au−Au collisions at √sNN=200 GeV from the STAR experiment. The π+π−π+π− 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 π+π−π+π− invariant mass spectrum of the coherent events exhibits a broad peak around 1540±40 MeV/c2 with a width of 570±60 MeV/c2, in agreement with the photoproduction data for the ρ0(1700). We do not observe a corresponding peak in the π+π− final state and measure an upper limit for the ratio of the branching fractions of the ρ0(1700) to π+π− and π+π−π+π− of 2.5% at 90% confidence level. The ratio of ρ0(1700) and ρ0(770) coherent production cross sections is measured to be 13.4±0.8stat.±4.4syst.%.

• Keywords (english): branching ratio; ratio; upper limit heavy ion; scattering gold peripheral pi; multiple production coherent interaction diffraction STAR mass spectrum; (2pi+ 2pi-) mass enhancement mass spectrum; (pi+ pi-) rho(1700); photoproduction rho(770)0; photoproduction cross section; ratio Brookhaven RHIC Coll rho(1700) --> 2pi+ 2pi- rho(1700) --> pi+ pi- 200 GeV-cms/nucleon
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: Physical Review C - Nuclear Physics
• Numbering: vol. 81, no. 4, 044901
• p-ISSN: 0556-2813
• e-ISSN: 1089-490X
• DOI: https://doi.org/10.1103/PhysRevC.81.044901
• URN:NBN: urn:nbn:hr:217:791802
• Publication: 2010
• Project: Number: 119-0982887-1006; Title (croatian): Istraživanje hadronskih sustava upotrebom relativističkih projektila; Leader: Mirko Planinić; Jurisdiction: Croatia; Funding stream: ZP
• Document URL: http://link.aps.org/doi/10.1103/PhysRevC.81.044901
• Type of resource: Text
• Access conditions: Open access
• Public note: Copyright (2010) by the American Physical Society. Received 4 December 2009; published 2 April 2010.
• Created on: 2019-11-02 17:17:30