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Physics

Faculty and Research Publications

2018

Quarkonia

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Observation Of Y(4s)→N′Y(1s), Belle Collaboration, Ratnappuli Luminda Kulasiri Oct 2018

Observation Of Y(4s)→N′Y(1s), Belle Collaboration, Ratnappuli Luminda Kulasiri

Faculty and Research Publications

We report the first observation of the hadronic transition Υ(4S)→η′Υ(1S), using 496  fb−1 data collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e−collider. We reconstruct the η′ meson through its decays to ρ0γ and to π+π−η, with η→γγ. We measure B(Υ(4S)→η′Υ(1S))=[3.43±0.88(stat)±0.21(syst)]×10−5, with a significance of 5.7σ.


Search For Υ ( 1 S , 2 S ) → Z + C Z ( ' ) C − And E + E − → Z + C Z ( ' ) C − At √ S = 10.52 , 10.58, And 10.867 Gev, S. Jia Et Al., Ratnappuli L. Kulasiri May 2018

Search For Υ ( 1 S , 2 S ) → Z + C Z ( ' ) C − And E + E − → Z + C Z ( ' ) C − At √ S = 10.52 , 10.58, And 10.867 Gev, S. Jia Et Al., Ratnappuli L. Kulasiri

Faculty and Research Publications

The first search for double charged charmoniumlike state production in Υ(1S) and Υ(2S) decays and in e+e− annihilation at √s=10.52, 10.58, and 10.867 GeV is conducted using data collected with the Belle detector at the KEKB asymmetric energy electron-positron collider. No significant signals are observed in any of the studied modes, and the 90% credibility level upper limits on their product branching fractions in Υ(1S) and Υ(2S) decays [B(Υ(1S,2S)→Z+cZ(')−c)×B(Z+c→π++c¯c) (c¯c=J/ψ, χc1(1P), ψ(2S))] and the product of Born cross section and branching fraction for e+e−→Z+cZ(')−c (σ(e+e−→Z+cZ(')−c)×B(Z+c→π++c¯c)) at √s=10.52, 10.58, and 10.867 GeV are determined. Here, Zc refers to the Zc(3900) and …


Angular Analysis Of The E + E − → Dðþd∓ Process Near The Open Charm Threshold Using Initial-State Radiation, V. Zhukova Et Al., Ratnappuli L. Kulasiri Jan 2018

Angular Analysis Of The E + E − → Dðþd∓ Process Near The Open Charm Threshold Using Initial-State Radiation, V. Zhukova Et Al., Ratnappuli L. Kulasiri

Faculty and Research Publications

We report a new measurement of the exclusive e+e−→D(*)±D*∓ cross sections as a function of the center-of-mass energy from the D(*)±D*∓ threshold through √s=6.0  GeV, using the initial-state radiation technique. The analysis is based on a data sample collected with the Belle detector with an integrated luminosity of 951  fb−1. The accuracy of the cross section measurement is increased by a factor of 2 over the first Belle study. We perform the first angular analysis of the e+e−→D*±D*∓process and decompose this exclusive cross section into three components corresponding to the D∗helicities.