Di-electron spectrum at mid-rapidity in p+p collisions at √s=200 GeV
We report on the mid-rapidity mass spectrum of di-electrons and cross sections of pseudoscalar and vector mesons via e+e- decays, from √s=200 GeV p+p collisions, measured by the large-acceptance experiment STAR at the Relativistic Heavy Ion Collider. The ratio of the di-electron continuum to the combinatorial background is larger than 10% over the entire mass range. Simulations of di-electrons from light-meson decays and heavy-flavor decays (charmonium and open charm correlation) are found to describe the data. The extracted ω→e+e- invariant yields are consistent with previous measurements. The mid-rapidity yields (dN/dy) of φ and J/ψ are extracted through their di-electron decay channels and are consistent with the previous measurements of φ→K+K- and J/ψ→e+e -. Our results suggest a new upper limit of the branching ratio of the η→e+e- of 1.7×10-5 at the 90% confidence level. © 2012 American Physical Society.
Adamczyk, L; Agakishiev, G; Aggarwal, MM; Ahammed, Z; Alakhverdyants, AV; Alekseev, I; Alford, J; Anderson, BD; Anson, CD; Arkhipkin, D; Aschenauer, E; Averichev, GS; Balewski, J; Banerjee, A; Barnovska, Z; Beavis, DR; Bellwied, R; Betancourt, MJ; Betts, RR; Bhasin, A; Bhati, AK; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, LC; Bordyuzhin, IG; Borowski, W; Bouchet, J; Brandin, AV; Brovko, SG; Bruna, E; Bueltmann, S; Bunzarov, I; Burton, TP; Butterworth, J; Cai, XZ; Caines, H; Calderón De La Barca Sánchez, M; Cebra, D; Cendejas, R; Cervantes, MC; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, HF; Chen, JH; Chen, JY; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chung, P; Chwastowski, J; Codrington, MJM; Corliss, R; Cramer, JG; Crawford, HJ; Cui, X; Davila Leyva, A; De Silva, LC; Debbe, RR; Dedovich, TG; Deng, J; Derradi De Souza, R; Dhamija, S; Didenko, L; Ding, F; Dion, A; Djawotho, P; Dong, X; Drachenberg, JL; Draper, JE; Du, CM; Dunkelberger, LE; Dunlop, JC; Efimov, LG; Elnimr, M; Engelage, J; Eppley, G; Eun, L; Evdokimov, O; Fatemi, R; Fazio, S; Fedorisin, J; Fersch, RG; Filip, P; Finch, E; Fisyak, Y; Gagliardi, CA; Gangadharan, DR; Geurts, F; Gibson, A; Gliske, S; Gorbunov, YN; Grebenyuk, OG; Grosnick, D; Gupta, S; Guryn, W; Haag, B
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