Cross sections for the reactionse+e−→K+K−π+π−,K+K−π0π0, andK+K−K+K−measured using initial-state radiation events

Abstract

We study the processes e+e−→K+K−π+π−γ, K+K−π0π0γ, and K+K−K+K−γ, where the photon is radiated from the initial state. About 84 000, 8000, and 4200 fully reconstructed events, respectively, are selected from 454 fb−1 of BABAR data. The invariant mass of the hadronic final state defines the e+e− center-of-mass energy, so that the K+K−π+π−γ data can be compared with direct measurements of the e+e−→K+K−π+π− reaction. No direct measurements exist for the e+e−→K+K−π0π0 or e+e−→K+K−K+K− reactions, and we present an update of our previous result based on a data sample that is twice as large. Studying the structure of these events, we find contributions from a number of intermediate states and extract their cross sections. In particular, we perform a more detailed study of the e+e−→ϕ(1020)ππγ reaction and confirm the presence of the Y(2175) resonance in the ϕ(1020)f0(980) and K+K−f0(980) modes. In the charmonium region, we observe the J/ψ in all three final states and in several intermediate states, as well as the ψ(2S) in some modes, and measure the corresponding products of branching fraction and electron width.35 MoreReceived 15 March 2011DOI:https://doi.org/10.1103/PhysRevD.86.012008© 2012 American Physical Society