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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, Zhulanov V. Measurement of R(D) and R(D^{*}) with a Semileptonic Tagging Method. PHYSICAL REVIEW LETTERS 2020; 124:161803. [PMID: 32383937 DOI: 10.1103/physrevlett.124.161803] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Accepted: 03/10/2020] [Indexed: 06/11/2023]
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.
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Adare A, Afanasiev S, Aidala C, Ajitanand NN, Akiba Y, Akimoto R, Al-Bataineh H, Alexander J, Alfred M, Al-Jamel A, Al-Ta'ani H, Angerami A, Aoki K, Apadula N, Aphecetche L, Aramaki Y, Armendariz R, Aronson SH, Asai J, Asano H, Aschenauer EC, Atomssa ET, Averbeck R, Awes TC, Azmoun B, Babintsev V, Bagoly A, Bai M, Baksay G, Baksay L, Baldisseri A, Bannier B, Barish KN, Barnes PD, Bassalleck B, Basye AT, Bathe S, Batsouli S, Baublis V, Bauer F, Baumann C, Baumgart S, Bazilevsky A, Belikov S, Belmont R, Bennett R, Berdnikov A, Berdnikov Y, Bhom JH, Bickley AA, Bjorndal MT, Blau DS, Boer M, Boissevain JG, Bok JS, Borel H, Boyle K, Brooks ML, Brown DS, Bryslawskyj J, Bucher D, Buesching H, Bumazhnov V, Bunce G, Burward-Hoy JM, Butsyk S, Camacho CM, Campbell S, Canoa Roman V, Caringi A, Castera P, Chai JS, Chang BS, Chang WC, Charvet JL, Chen CH, Chernichenko S, Chi CY, Chiba J, Chiu M, Choi IJ, Choi JB, Choi S, Choudhury RK, Christiansen P, Chujo T, Chung P, Churyn A, Chvala O, Cianciolo V, Citron Z, Cleven CR, Cobigo Y, Cole BA, Comets MP, Conesa Del Valle Z, Connors M, Constantin P, Csanád M, Csörgő T, Dahms T, Dairaku S, Danchev I, Danley TW, Das K, Datta A, Daugherity MS, David G, Dayananda MK, Deaton MB, Dehmelt K, Delagrange H, Denisov A, d'Enterria D, Deshpande A, Desmond EJ, Dharmawardane KV, Dietzsch O, Ding L, Dion A, Do JH, Donadelli M, D'Orazio L, Drachenberg JL, Drapier O, Drees A, Drees KA, Dubey AK, Durham JM, Durum A, Dutta D, Dzhordzhadze V, Edwards S, Efremenko YV, Egdemir J, Ellinghaus F, Emam WS, Engelmore T, Enokizono A, En'yo H, Espagnon B, Esumi S, Eyser KO, Fadem B, Fan W, Feege N, Fields DE, Finger M, Finger M, Fleuret F, Fokin SL, Forestier B, Fraenkel Z, Frantz JE, Franz A, Frawley AD, Fujiwara K, Fukao Y, Fung SY, Fusayasu T, Gadrat S, Gainey K, Gal C, Gallus P, Garg P, Garishvili A, Garishvili I, Gastineau F, Ge H, Germain M, Glenn A, Gong H, Gong X, Gonin M, Gosset J, Goto Y, Granier de Cassagnac R, Grau N, Greene SV, Grim G, Grosse Perdekamp M, Gunji T, Guo L, Gustafsson HÅ, Hachiya T, Hadj Henni A, Haegemann C, Haggerty JS, Hagiwara MN, Hahn KI, Hamagaki H, Hamblen J, Han R, Hanks J, Harada H, Hartouni EP, Haruna K, Harvey M, Hasegawa S, Haseler TOS, Hashimoto K, Haslum E, Hasuko K, Hayano R, He X, Heffner M, Hemmick TK, Hester T, Heuser JM, Hiejima H, Hill JC, Hill K, Hobbs R, Hodges A, Hohlmann M, Hollis RS, Holmes M, Holzmann W, Homma K, Hong B, Horaguchi T, Hori Y, Hornback D, Hotvedt N, Huang J, Huang S, Hur MG, Ichihara T, Ichimiya R, Iinuma H, Ikeda Y, Imai K, Imrek J, Inaba M, Inoue Y, Iordanova A, Isenhower D, Isenhower L, Ishihara M, Isobe T, Issah M, Isupov A, Ivanishchev D, Iwanaga Y, Jacak BV, Javani M, Ji Z, Jia J, Jiang X, Jin J, Jinnouchi O, Johnson BM, Jones T, Joo KS, Jouan D, Jumper DS, Kajihara F, Kametani S, Kamihara N, Kamin J, Kaneta M, Kaneti S, Kang BH, Kang JH, Kang JS, Kanou H, Kapustinsky J, Karatsu K, Kasai M, Kawagishi T, Kawall D, Kawashima M, Kazantsev AV, Kelly S, Kempel T, Khachatryan V, Khanzadeev A, Kijima KM, Kikuchi J, Kim A, Kim BI, Kim C, Kim DH, Kim DJ, Kim E, Kim EJ, Kim HJ, Kim KB, Kim M, Kim SH, Kim YJ, Kim YK, Kim YS, Kincses D, Kinney E, Kiriluk K, Kiss Á, Kistenev E, Kiyomichi A, Klatsky J, Klay J, Klein-Boesing C, Kleinjan D, Kline P, Kochenda L, Kochetkov V, Komatsu Y, Komkov B, Konno M, Koster J, Kotchetkov D, Kotov D, Kozlov A, Král A, Kravitz A, Krizek F, Kroon PJ, Kubart J, Kunde GJ, Kurgyis B, Kurihara N, Kurita K, Kurosawa M, Kweon MJ, Kwon Y, Kyle GS, Lacey R, Lai YS, Lajoie JG, Layton D, Lebedev A, Le Bornec Y, Leckey S, Lee B, Lee DM, Lee J, Lee KB, Lee KS, Lee MK, Lee SH, Lee SR, Lee T, Leitch MJ, Leite MAL, Leitgab M, Lenzi B, Leung YH, Lewis B, Lewis NA, Li X, Li X, Li XH, Lichtenwalner P, Liebing P, Lim H, Lim SH, Linden Levy LA, Liška T, Litvinenko A, Liu H, Liu MX, Lökös S, Love B, Lynch D, Maguire CF, Majoros T, Makdisi YI, Makek M, Malakhov A, Malik MD, Manion A, Manko VI, Mannel E, Mao Y, Mašek L, Masui H, Masumoto S, Matathias F, McCain MC, McCumber M, McGaughey PL, McGlinchey D, McKinney C, Means N, Mendoza M, Meredith B, Miake Y, Mibe T, Mignerey AC, Mihalik DE, Mikeš P, Miki K, Miller TE, Milov A, Mioduszewski S, Mishra DK, Mishra GC, Mishra M, Mitchell JT, Mitrovski M, Mitsuka G, Miyachi Y, Miyasaka S, Mohanty AK, Mohapatra S, Moon HJ, Moon T, Morino Y, Morreale A, Morrison DP, Morrow SI, Moss JM, Motschwiller S, Moukhanova TV, Mukhopadhyay D, Murakami T, Murata J, Mwai A, Nagae T, Nagamiya S, Nagashima K, Nagata Y, Nagle JL, Naglis M, Nagy MI, Nakagawa I, Nakamiya Y, Nakamura KR, Nakamura T, Nakano K, Nam S, Nattrass C, Nederlof A, Newby J, Nguyen M, Nihashi M, Niida T, Norman BE, Nouicer R, Novák T, Novitzky N, Nyanin AS, Nystrand J, Oakley C, O'Brien E, Oda SX, Ogilvie CA, Ohnishi H, Ojha ID, Oka M, Okada K, Omiwade OO, Onuki Y, Orjuela Koop JD, Osborn JD, Oskarsson A, Otterlund I, Ouchida M, Ozawa K, Pak R, Pal D, Palounek APT, Pantuev V, Papavassiliou V, Park BH, Park IH, Park J, Park S, Park SK, Park WJ, Pate SF, Patel L, Patel M, Pei H, Peng JC, Peng W, Pereira H, Perepelitsa DV, Peresedov V, Peressounko DY, PerezLara CE, Petti R, Pinkenburg C, Pisani RP, Proissl M, Purschke ML, Purwar AK, Qu H, Radzevich PV, Rak J, Rakotozafindrabe A, Ravinovich I, Read KF, Rembeczki S, Reuter M, Reygers K, Reynolds D, Riabov V, Riabov Y, Richardson E, Richford D, Rinn T, Roach D, Roche G, Rolnick SD, Romana A, Rosati M, Rosen CA, Rosendahl SSE, Rosnet P, Rowan Z, Rukoyatkin P, Runchey J, Ružička P, Rykov VL, Ryu SS, Sahlmueller B, Saito N, Sakaguchi T, Sakai S, Sakashita K, Sakata H, Sako H, Samsonov V, Sano M, Sano S, Sarsour M, Sato HD, Sato S, Sato T, Sawada S, Schmoll BK, Sedgwick K, Seele J, Seidl R, Semenov AY, Semenov V, Sen A, Seto R, Sharma D, Shea TK, Shein I, Shevel A, Shibata TA, Shigaki K, Shimomura M, Shohjoh T, Shoji K, Shukla P, Sickles A, Silva CL, Silvermyr D, Silvestre C, Sim KS, Singh BK, Singh CP, Singh V, Skoby MJ, Skutnik S, Slunečka M, Smith WC, Soldatov A, Soltz RA, Sondheim WE, Sorensen SP, Sourikova IV, Staley F, Stankus PW, Stenlund E, Stepanov M, Ster A, Stoll SP, Sugitate T, Suire C, Sukhanov A, Sullivan JP, Sun J, Sun Z, Sziklai J, Tabaru T, Takagi S, Takagui EM, Takahara A, Taketani A, Tanabe R, Tanaka KH, Tanaka Y, Taneja S, Tanida K, Tannenbaum MJ, Tarafdar S, Taranenko A, Tarján P, Tennant E, Themann H, Thomas D, Thomas TL, Tieulent R, Todoroki T, Togawa M, Toia A, Tojo J, Tomášek L, Tomášek M, Tomita Y, Torii H, Towell RS, Tram VN, Tserruya I, Tsuchimoto Y, Tsuji T, Tuli SK, Tydesjö H, Tyurin N, Ueda Y, Ujvari B, Vale C, Valle H, van Hecke HW, Vargyas M, Vazquez-Zambrano E, Veicht A, Velkovska J, Vértesi R, Vinogradov AA, Virius M, Vossen A, Vrba V, Vznuzdaev E, Wagner M, Walker D, Wang XR, Watanabe D, Watanabe K, Watanabe Y, Watanabe YS, Wei F, Wei R, Wessels J, White SN, Willis N, Winter D, Wolin S, Wong CP, Woody CL, Wright RM, Wysocki M, Xia B, Xie W, Xu C, Xu Q, Yamaguchi YL, Yamaura K, Yang R, Yanovich A, Yasin Z, Ying J, Yokkaichi S, Yoo JH, You Z, Young GR, Younus I, Yu H, Yushmanov IE, Zajc WA, Zaudtke O, Zelenski A, Zhang C, Zharko S, Zhou S, Zimamyi J, Zolin L, Zou L. Beam Energy and Centrality Dependence of Direct-Photon Emission from Ultrarelativistic Heavy-Ion Collisions. PHYSICAL REVIEW LETTERS 2019; 123:022301. [PMID: 31386493 DOI: 10.1103/physrevlett.123.022301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 04/27/2019] [Indexed: 06/10/2023]
Abstract
The PHENIX collaboration presents first measurements of low-momentum (0.4<p_{T}<3 GeV/c) direct-photon yields from Au+Au collisions at sqrt[s_{NN}]=39 and 62.4 GeV. For both beam energies the direct-photon yields are substantially enhanced with respect to expectations from prompt processes, similar to the yields observed in Au+Au collisions at sqrt[s_{NN}]=200. Analyzing the photon yield as a function of the experimental observable dN_{ch}/dη reveals that the low-momentum (>1 GeV/c) direct-photon yield dN_{γ}^{dir}/dη is a smooth function of dN_{ch}/dη and can be well described as proportional to (dN_{ch}/dη)^{α} with α≈1.25. This scaling behavior holds for a wide range of beam energies at the Relativistic Heavy Ion Collider and the Large Hadron Collider, for centrality selected samples, as well as for different A+A collision systems. At a given beam energy, the scaling also holds for high p_{T} (>5 GeV/c), but when results from different collision energies are compared, an additional sqrt[s_{NN}]-dependent multiplicative factor is needed to describe the integrated-direct-photon yield.
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