Measurement of the CKM angle phi3 using B->DK at Belle II

Manish Kumar ; Kavita Lalwani ; Karim Trabelsi ; Prashant Krishnan

08 July 2018
FPCP 2018, Hyderabad,INDIA

Abstract: The precise determination of the CKM angle phi3 is highly desirable to scrutinise the consistency of the Standard Model and to probe for the presence of new physics. There have been many efforts by BABAR, Belle and LHCb to measure this angle but due to the small data samples so far produced, phi3 is poorly determined. Hence, a precision measurement of phi3 is required. In this work, the Belle II experimental facility at the SuperKEKB e^+e^− collider will be used, which is the upgraded version of Belle at KEKB; SuperKEKB is an energy-asymmetric e^+e^− collider at KEK Japan. The design luminosity is 8×10^35 cm^−2s^−1 and the Belle II experiment will record a data sample that corresponds to an integrated luminosity of 50 ab^−1, which is a factor of 50 more than the Belle experiment. This data sample will shed light on new physics beyond the Standard Model via high precision measurements of heavy flavor decays and searches for rare signal, including a precision measurement of the CKM angle phi3. In this poster presentation, the preliminary results of Monte Carlo (MC) simulation studies dedicated to the measurement of phi3 using the decay B -> DK, where D -> K0_Spi^+pi^−, will be presented. Further, two important variables the energy difference between the reconstructed energy of BBbar pairs and center-of-mass energy of Υ(4S) deltaE and the beam constrained mass (M_bc) are reconstructed for signal events and the two background: B → Dpi and combinatorial type continuum background. These distributions are further compared for different versions of the reconstruction and background conditions to determine the efficiency of selecting signal events and validate the reconstruction performance for further analysis. Further, an improved precision on the measurement of the CKM angle phi3 by extrapolating the measurement results at integrated luminosity of 50 ab^−1 will also be discussed. This work will give an overview about the status of this analysis.

Keyword(s): CP Violation ; CKM angle phi3 ; Belle II ; SuperKEKB

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 Record created 2018-07-08, last modified 2018-07-13

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