High-statistics study ofϒ(2S)→π+π−ϒ(

Abstract

A detailed investigation of the decay Y(2S)-+.rr+.rr-T( IS) has been made from 128 000 Y ( 2 S ) decays observed in the CLEO detector at the Cornell Electron Storage Ring (CESR). We find this branching ratio to be (19.1rtl.2rtO.6)%. The properties of the rrr system have been studied using 491 exclusive events of the type T (ZS)+r+.rr-T( IS), Y ( 1 S ) + e + e P or p + p -. Assuming e-p universality we find B ( T ( l S ) + p + p -) =(2.84+.0.18+.0.20)%. A search for Y ( 2 S ) + r ] Y ( 1s) yieldsan upper limit of 1% at the 90% confidence level for this branching ratio. We have also searched for [ Y ( 2 S ) or Y ( 3S)]+rr+.rr-Y( IS), Y ( lS)+noninteracting particles.

Mass bounds on a very light neutralino

“…To our knowledge, this idea was first proposed in [197], as a test of the SM neutral current, and it has since been widely employed [198][199][200][201]. In [202] it was proposed as a method to look for physics beyond the SM, then a light gravitino.…”

Effect of theηηchannel and interference phenomena in the two-pion transitions of charmonia and bottomonia

“…For the decay J/ψ → φπ + π − data were taken from Mark III, DM2 and BES II Collaborations; for ψ(2S ) → J/ψ(π + π − and π 0 π 0 ) -from Mark II and Crystal Ball(80) (see also in [3]). For Υ(2S ) → Υ(1S )(π + π − and π 0 π 0 ) data were used from ARGUS [4], CLEO [5], CUSB [6], and Crystal Ball [7] Collaborations; for [10] and Belle [11]; for Υ(5S ) → Υ(1S , 2S , 3S )π + π − -from Belle Collaboration [11].…”

Determination of closed-flavour πJ/ψ and πϒ cross sections at low energies from dipion decays

“…Here we consider the dipion decays of heavy quarkonia below open-flavor thresholds, which have been observed in four cases, ψ ′ → ππJ/ψ [11,12,13], Υ ′ → ππΥ [14,15,16,17] Υ ′′ → ππΥ [15,16,17,18,19] and Υ ′′ → ππΥ ′ [15,16,17,18,19]. These transitions are quite weak, with partial widths of only ca.…”