1. Measurement of R(D) and R(D^{*}) with a Semileptonic Tagging Method.
- Author
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Caria G, Urquijo P, Adachi I, Aihara H, Al Said S, Asner DM, Atmacan H, Aushev T, Babu V, Badhrees I, Bahinipati S, Bakich AM, Behera P, Beleño C, Bennett J, Bhuyan B, Bilka T, Biswal J, Bozek A, Bračko M, Browder TE, Campajola M, Červenkov D, Chang P, Cheaib R, Chekelian V, Chen A, Cheon BG, Chilikin K, Cho HE, Cho K, Choi Y, Choudhury S, Cinabro D, Cunliffe S, Dash N, De Nardo G, Di Capua F, Di Carlo S, Doležal Z, Dong TV, Eidelman S, Epifanov D, Fast JE, Ferber T, Ferlewicz D, Fulsom BG, Garg R, Gaur V, Gabyshev N, Garmash A, Giri A, Goldenzweig P, Greenwald D, Grzymkowska O, Guan Y, Hartbrich O, Hayasaka K, Hayashii H, Higuchi T, Hou WS, Hsu CL, Iijima T, Inami K, Inguglia G, Ishikawa A, Itoh R, Iwasaki M, Iwasaki Y, Jacobs WW, Jeon HB, Jia S, Jin Y, Joffe D, Joo KK, Kaliyar AB, Kang KH, Karyan G, Kawasaki T, Kichimi H, Kim CH, Kim DY, Kim HJ, Kim KT, Kim SH, Kinoshita K, Kodyš P, Korpar S, Kotchetkov D, Križan P, Kroeger R, Krohn JF, Krokovny P, Kuhr T, Kumar R, Kwon YJ, Lange JS, Lee IS, Lee JK, Lee SC, Li LK, Li YB, Li Gioi L, Libby J, Lieret K, Liventsev D, Luo T, MacQueen C, Masuda M, Matsuda T, Matvienko D, Merola M, Metzner F, Miyabayashi K, Mohanty GB, Moon TJ, Mori T, Mussa R, Nakamura KR, Nakao M, Nath KJ, Nayak M, Nisar NK, Nishida S, Nishimura K, Ogawa K, Ono H, Onuki Y, Oskin P, Pakhlov P, Pakhlova G, Pal B, Pang T, Park H, Park SH, Patra S, Paul S, Pedlar TK, Pestotnik R, Piilonen LE, Popov V, Prencipe E, Prim MT, Rabusov A, Resmi PK, Ritter M, Rozanska M, Russo G, Sahoo D, Sakai Y, Sandilya S, Santelj L, Sanuki T, Savinov V, Schneider O, Schnell G, Schueler J, Schwanda C, Schwartz AJ, Seino Y, Senyo K, Sevior ME, Shebalin V, Shiu JG, Shwartz B, Simon F, Sokolov A, Solovieva E, Starič M, Stottler ZS, Sumiyoshi T, Sutcliffe W, Takizawa M, Tamponi U, Tanida K, Tenchini F, Trabelsi K, Uchida M, Uglov T, Uno S, Usov Y, Vahsen SE, Van Tonder R, Varner G, Varvell KE, Vossen A, Waheed E, Wang B, Wang CH, Wang MZ, Wang P, Wang XL, Watanuki S, Wiechczynski J, Won E, Yamamoto H, Yang SB, Ye H, Yin JH, Yuan CZ, Zhang ZP, Zhilich V, Zhukova V, and Zhulanov V
- Abstract
The experimental results on the ratios of branching fractions R(D)=B(B[over ¯]→Dτ^{-}ν[over ¯]_{τ})/B(B[over ¯]→Dℓ^{-}ν[over ¯]_{ℓ}) and R(D^{*})=B(B[over ¯]→D^{*}τ^{-}ν[over ¯]_{τ})/B(B[over ¯]→D^{*}ℓ^{-}ν[over ¯]_{ℓ}), where ℓ denotes an electron or a muon, show a long-standing discrepancy with the standard model predictions, and might hint at a violation of lepton flavor universality. We report a new simultaneous measurement of R(D) and R(D^{*}), based on a data sample containing 772×10^{6} BB[over ¯] events recorded at the ϒ(4S) resonance with the Belle detector at the KEKB e^{+}e^{-} collider. In this analysis the tag-side B meson is reconstructed in a semileptonic decay mode and the signal-side τ is reconstructed in a purely leptonic decay. The measured values are R(D)=0.307±0.037±0.016 and R(D^{*})=0.283±0.018±0.014, where the first uncertainties are statistical and the second are systematic. These results are in agreement with the standard model predictions within 0.2, 1.1, and 0.8 standard deviations for R(D), R(D^{*}), and their combination, respectively. This work constitutes the most precise measurements of R(D) and R(D^{*}) performed to date as well as the first result for R(D) based on a semileptonic tagging method.
- Published
- 2020
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