Improved Measurement of the Electroweak Penguin Process B->Xsll

TL;DR

This paper reports an improved measurement of the branching fraction for the electroweak penguin decay B->Xsl+l- using a large dataset from the Belle detector, providing more precise results for this rare process.

Contribution

The study presents a more accurate measurement of Br(B->Xsll) with a larger dataset and refined reconstruction techniques, advancing understanding of electroweak penguin processes.

Findings

Measured Br(B->Xsll) = (4.11 ± 0.83 (stat) +0.74 -0.70 (syst)) × 10^{-6} for m(ll) > 0.2 GeV.

Utilized a sample of 152 million BB-bar events from the Belle detector.

Reconstructed Xs from K±, K0s, and up to four pions, with at most one neutral pion.

Abstract

We present an improved measurement of the branching fraction for the electroweak penguin process B->Xsl+l-, where l is an electron or a muon and Xs is a hadronic system containing an s-quark. The measurement is based on a sample of 152 * 10^6 ~ Upsilon(4S) -> BB-bar events collected with the Belle detector at the KEKB e+e- asymmetric-energy collider. The Xs hadronic system is reconstructed from one K+- or K0s and up to four pions, where at most one pion can be neutral. Summing over both lepton flavors, the inclusive branching fraction is measured to be Br(B->Xsll)=(4.11 +- 0.83(stat.) +0.74 -0.70 (syst.) )*10^{-6} for m(ll) > 0.2GeV.