The resonance parameters of the charmonium ground state, eta(c)(1(l)S(0)), have been measured by means of the reaction (p) over barp --> eta(c) --> gammagamma. The mass and total width are determined to be 2984.1 +/- 2.1 +/- 1.0 MeV/c(2) and 20.4(-6.7)(+7.7) +/- 2.0 Mev, respectively. The product of branching ratios B((p) over barp --> eta(c))B(eta(c) --> gammagamma) is determined to be (22.4(-3.7)(+3.8) +/- 2.0) x 10(-8), from which B(eta(c) --> gammagamma) = (1.87(-0.31-0.50)(+0.32+0.95)) x 10(-4), and Gamma(eta(c) --> gammagamma) = 3.8(-1.0-1.0)(+1.1+1-9) keV are derived using B(eta(c) --> (p) over barp) (12 +/- 4) x 10(-4) from the literature. (C) 2003 Published by Elsevier B.V.
Measurement of the resonance parameters of the charmonium ground state, eta(c)(1(1)S(0))
ARGIRO', Stefano;MENICHETTI, Ezio;OBERTINO, Maria Margherita;
2003-01-01
Abstract
The resonance parameters of the charmonium ground state, eta(c)(1(l)S(0)), have been measured by means of the reaction (p) over barp --> eta(c) --> gammagamma. The mass and total width are determined to be 2984.1 +/- 2.1 +/- 1.0 MeV/c(2) and 20.4(-6.7)(+7.7) +/- 2.0 Mev, respectively. The product of branching ratios B((p) over barp --> eta(c))B(eta(c) --> gammagamma) is determined to be (22.4(-3.7)(+3.8) +/- 2.0) x 10(-8), from which B(eta(c) --> gammagamma) = (1.87(-0.31-0.50)(+0.32+0.95)) x 10(-4), and Gamma(eta(c) --> gammagamma) = 3.8(-1.0-1.0)(+1.1+1-9) keV are derived using B(eta(c) --> (p) over barp) (12 +/- 4) x 10(-4) from the literature. (C) 2003 Published by Elsevier B.V.
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