Event-by-event fluctuations of the multiplicities of inclusive charged particles and photons at forward rapidity in Au+Au collisions at √SNN=200 GeV have been studied. The dominant contribution to such fluctuations is expected to come from correlated production of charged and neutral pions. We search for evidence of dynamical fluctuations of different physical origins. Observables constructed out of moments of multiplicities are used as measures of fluctuations. Mixed events and model calculations are used as base lines. Results are compared to the dynamical net-charge fluctuations measured in the same acceptance. A nonzero statistically significant signal of dynamical fluctuations is observed in excess to the model prediction when charged particles and photons are measured in the same acceptance. We find that, unlike dynamical net-charge fluctuation, charge-neutral fluctuation is not dominated by correlation owing to particle decay. Results are compared to the expectations based on the generic production mechanism of pions owing to isospin symmetry, for which no significant (<1%) deviation is observed.

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Published in Physical Review C: Nuclear Physics, v. 91, no. 3, article 034905, p. 1-13.

©2015 American Physical Society

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Collectively the authors are known as the STAR Collaboration. Due to the large number of authors involved, only the first 10 and the ones affiliated with the University of Kentucky are listed in the author section above. For the complete list of authors, please download this article or visit the following link: http://dx.doi.org/10.1103/PhysRevC.91.034905

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This work was supported in part by the Offices of NP and HEP within the U.S. DOE Office of Science, the U.S. NSF, CNRS/IN2P3; FAPESP CNPq of Brazil; the Ministry of Education and Science of the Russian Federation, NNSFC, CAS, MoST, and MoE of China; the Korean Research Foundation; GA and MSMT of the Czech Republic; FIAS of Germany; DAE, DST, and CSIR of India; the National Science Centre of Poland; National Research Foundation (NRF-2012004024); the Ministry of Science, Education and Sports of the Republic of Croatia; and RosAtom of Russia.

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