Measurement of B(Bs→DsX) with Bs semileptonic tagging

B Wang,O Werbycka,R Van Tonder,N Dash,K Lieret,C Macqueen,D Matvienko,T Bilka,J Libby,S Ogawa,L Cao,Y Seino,I Badhrees,V Babu,D Kotchetkov,K Tanida,D Liventsev,C Beleño,T Uglov,S Jia,R Ayad,K Inami,D Cinabro,S Pardi,T Kuhr,K Nishimura,K Senyo,Y Choi,S Uno,F Di Capua,E Won,E Waheed,K Hayasaka,K Chilikin,G Bonvicini,M Nayak,R Pestotnik,F Tenchini,H Park,T Sanuki,E Solovieva,D Joffe,A Bobrov,A Vinokurova,R Mizuk,S Cunliffe,S Korpar,C Kiesling,A Rostomyan,M Nakao,Y Iwasaki,Z Doležal,G Karyan,M Merola,L Li Gioi,K Miyabayashi,P Krokovny,M Masuda,C Schwanda,M Campajola,E Prencipe,H Hayashii,T Ferber,A Ishikawa,Y Usov,M Iwasaki,T Aushev,R Kroeger,J Macnaughton,P Goldenzweig,S Sandilya,M Starič,P Križan,Y Onuki,V Gaur,V Bhardwaj,S Di Carlo,T Pang,R Mussa,O Schneider,G Schnell,A Chen,H Ono,S Nishida,M Bračko,A Garmash,D Epifanov,A Kuzmin,T Matsuda,T Sumiyoshi,K Kinoshita,D Červenkov,S Eidelman,V Savinov,G Pakhlova,Y Yusa,J E Fast ,T K Pedlar ,V Zhulanov,S K Choi ,K J Nath ,H E Cho ,S H Kim ,M Ritter,R Garg,V Shebalin,S.-H Park,H Ye,A Sokolov,V Zhilich,G Russo,Jyoti Prakash Biswal ,Y B Li ,M Takizawa,J Y Lee ,J G Shiu ,W.-S Hou,I S Lee ,G B Mohanty ,Y H Guan ,V Zhukova,S C Lee ,J Strube ,M.-Z Wang,H Aihara,L Šantelj ,M E Sevior ,B K Pal ,Y Jin,P Wang,D Y Kim ,K T Kim ,A Giri,C H Wang ,K Cho,P K Behera ,A J Schwartz ,B G Fulsom ,A B Kaliyar ,L E Piilonen ,P Kodyš,J V Bennett ,Z P Zhang ,M Bessner,K K Joo ,A M Bakich ,L K Li ,T Luo,M T Prim ,J S Lange ,N K Nisar ,A Bożek ,S B Yang ,V Popov,D M Asner ,Y J Kwon ,G Varner,K H Kang ,T E Browder ,Null Author_Id

doi:10.1103/physrevd.105.012004

Abstract

We report the first direct measurement of the inclusive branching fraction ${\mathcal B}(B_s \rightarrow D_s X)$ via $B_s$ tagging in $e^+e^-\to\Upsilon$(5S) events. Tagging is accomplished through a partial reconstruction of semileptonic decays $B_s \rightarrow D_s X \ell \nu$, where $X$ denotes unreconstructed additional hadrons or photons and $\ell$ is an electron or muon. With 121.4 fb$^{-1}$ of data collected at the $\Upsilon$(5S) resonance by the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider, we obtain ${\mathcal B}(B_s \rightarrow D_s X)$ = $(60.2 \pm 5.8 \pm 2.3)$\%, where the first uncertainty is statistical and the second is systematic.

Highlights

We report the first direct measurement of the inclusive branching fraction BðBs → DsXÞ via Bs tagging in eþe− → Υð5SÞ events
With 121.4 fb−1 of data collected at the Υð5SÞ resonance by the Belle detector at the KEKB asymmetric-energy eþe− collider, we obtain BðBs → DsXÞ 1⁄4 ð60.2 Æ 5.8 Æ 2.3Þ%, where the first uncertainty is statistical and the second is systematic
The branching fraction for the inclusive decay Bs → DsX plays an important role in the determination of the Bs production rate in Υð5SÞ events [4]

Summary

Published by the American Physical Society

We report the first direct measurement of the inclusive branching fraction BðBs → DsXÞ via Bs tagging in eþe− → Υð5SÞ events. We tag Bs events through a “partial reconstruction” of the semileptonic decay B0s → D−s Xlþν, with the D−s modes φπ− and K0SK−, using a procedure similar to one applied at the Υð4SÞ resonance [15], where a lepton (electron or muon) is paired with a charm meson to form a B candidate. For both signal and cross-feed, the number of events found in a data set depends on many of the same factors: number of Bs events, branching fractions of the reconstructed Ds modes, branching fractions of Bs → DsXlν, and Bs → DsX The reason for this is clear: the two types have a common origin, differing only in the assigning of Ds to tag- vs signal-side. The first correction term is found to be negligible (less than 10−3), and the second is εDsl 2εDs

We thus find

Findings

Reconstruction efficiency