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First Evidence for cos 2β > 0 and Resolution of the Cabibbo-Kobayashi-Maskawa Quark-Mixing Unitarity Triangle Ambiguity

Adachi, I. and Chao, D. S. and Cheng, C. H. and Echenard, B. and Flood, K. T. and Hitlin, D. G. and Kim, J. and Li, Y. and Miyashita, T. S. and Ongmongkolkul, P. and Porter, F. C. (2018) First Evidence for cos 2β > 0 and Resolution of the Cabibbo-Kobayashi-Maskawa Quark-Mixing Unitarity Triangle Ambiguity. Physical Review Letters, 121 (26). Art. No. 261801. ISSN 0031-9007.

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We present first evidence that the cosine of the CP-violating weak phase 2β is positive, and hence exclude trigonometric multifold solutions of the Cabibbo-Kobayashi-Maskawa (CKM) Unitarity Triangle using a time-dependent Dalitz plot analysis of B^0 → D(*)h^0 with D → K^0_Sπ+π− decays, where h^0 ∈ {π^0,η,ω} denotes a light unflavored and neutral hadron. The measurement is performed combining the final data sets of the BABAR and Belle experiments collected at the Υ(4S) resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain (471±3) × 10^6BB pairs recorded by the BABAR detector and (772±11) × 10^6BB pairs recorded by the Belle detector. The results of the measurement are sin2β = 0.80±0.14(stat)±0.06(syst)±0.03(model) and cos2β = 0.91±0.22(stat)±0.09(syst)±0.07(model). The result for the direct measurement of the angle β of the CKM Unitarity Triangle is β = [22.5±4.4(stat)±1.2(syst)±0.6(model)]°. The measurement assumes no direct CP violation in B^0 → D(*)h^0 decays. The quoted model uncertainties are due to the composition of the D^0 → K^0Sπ+π− decay amplitude model, which is newly established by performing a Dalitz plot amplitude analysis using a high-statistics e+e− → cc data sample. CP violation is observed in B^0 → D(*)h^0 decays at the level of 5.1 standard deviations. The significance for cos2β > 0 is 3.7 standard deviations. The trigonometric multifold solution π/2 – β = (68.1±0.7)° is excluded at the level of 7.3 standard deviations. The measurement resolves an ambiguity in the determination of the apex of the CKM Unitarity Triangle.

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Hitlin, D. G.0000-0003-4028-6982
Porter, F. C.0000-0003-1948-8889
Additional Information:© 2018 Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3. Received 17 April 2018; revised manuscript received 22 August 2018; published 26 December 2018. We thank the PEP-II and KEKB groups for the excellent operation of the accelerators. The BABAR experiment acknowledges the substantial dedicated effort from the computing organizations for their support. The collaborating institutions wish to thank SLAC for its support and kind hospitality. The Belle experiment wishes to acknowledge the KEK cryogenics group for efficient solenoid operations; and the KEK computer group, the NII, and PNNL/EMSL for valuable computing and SINET5 network support. This work was supported by MEXT, JSPS and Nagoya’s TLPRC (Japan); ARC (Australia); FWF (Austria); NSERC (Canada); NSFC and CCEPP (China); MSMT (Czechia); CEA and CNRS-IN2P3 (France); BMBF, CZF, DFG, EXC153, and VS (Germany); DST (India); INFN (Italy); MOE, MSIP, NRF, RSRI, FLRFAS project and GSDC of KISTI (Korea); FOM (The Netherlands); NFR (Norway); MNiSW and NCN (Poland); MES and RFAAE (Russia); ARRS (Slovenia); IKERBASQUE and MINECO (Spain); SNSF (Switzerland); MOE and MOST (Taiwan); STFC (United Kingdom); BSF (USA-Israel); and DOE and NSF (USA). Individuals have received support from the Marie Curie EIF (European Union) and the A. P. Sloan Foundation (USA).
Funding AgencyGrant Number
Ministry of Education, Culture, Sports, Science and Technology (MEXT)UNSPECIFIED
Japan Society for the Promotion of Science (JSPS)UNSPECIFIED
Australian Research CouncilUNSPECIFIED
Fonds zur Förderung der wissenschaftlichen Forschung (FWF)UNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
National Natural Science Foundation of ChinaUNSPECIFIED
Center for Excellence in Particle Physics (CCEPP)UNSPECIFIED
Ministry of Education, Youth and Sports of the Czech RepublicUNSPECIFIED
Commissariat à l'énergie atomique (CEA)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Institut National de Physique Nucléaire et de Physique des Particules (IN2P3)UNSPECIFIED
Bundesministerium für Bildung und Forschung (BMBF)UNSPECIFIED
Deutsche Forschungsgemeinschaft (DFG)UNSPECIFIED
Department of Science and Technology (India)UNSPECIFIED
Istituto Nazionale di Fisica Nucleare (INFN)UNSPECIFIED
Ministry of Education (Korea)UNSPECIFIED
Ministry of Science, ICT and Future Planning (Korea)UNSPECIFIED
National Research Foundation of KoreaUNSPECIFIED
Korea Institute of Science and Technology Information (KISTI)UNSPECIFIED
Stichting voor Fundamenteel Onderzoek der Materie (FOM)UNSPECIFIED
Research Council of NorwayUNSPECIFIED
Ministerstwo Nauki i Szkolnictwa Wyższego (MNiSW)UNSPECIFIED
National Science Centre (Poland)UNSPECIFIED
Ministry of Education and Science of the Russian Federation UNSPECIFIED
Slovenian Research AgencyUNSPECIFIED
Ministerio de Economía, Industria y Competitividad (MINECO)UNSPECIFIED
Swiss National Science Foundation (SNSF)UNSPECIFIED
Ministry of Education (Taipei)UNSPECIFIED
Ministry of Science and Technology (Taipei)UNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
Binational Science Foundation (USA-Israel)UNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Marie Curie FellowshipUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Issue or Number:26
Record Number:CaltechAUTHORS:20190104-090808118
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92086
Deposited By: Tony Diaz
Deposited On:04 Jan 2019 17:48
Last Modified:03 Oct 2019 20:40

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