2012/09/30 by Bhubanjyoti Bhattacharya, BHUBANJYOTI BHATTACHARYA, Alakabha Datta +3 · 1 citation
Physics and Astronomy · #Neutrino Physics Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ex #hep-ph
paper · pdf · doi:10.1142/s0217751x13500632
17 pages, latex, extensive discussion of theoretical error added, reference added. Further revision: even more detailed discussion of theoretical error added, as well as an explanation of why the NP strong phase is negligible
arxiv created 2013/04/29 · openalex publication_date 2013/06/05 · arxiv updated 2015/06/11 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
The most common decay used for measuring 2betas, the phase of Bs-Bsbar mixing, is Bs -> J/psi phi. This decay is dominated by the colour-suppressed tree diagram, but there are other contributions due to gluonic and electroweak penguin diagrams. These are often referred to as "penguin pollution" (PP) because their inclusion in the amplitude leads to a theoretical error in the extraction of 2betas from the data. In the standard model (SM), it is estimated that the PP is negligible, but there is some uncertainty as to its exact size. Now, phis^ccs (the measured value of 2betas) is small, in agreement with the SM, but still has significant experimental errors. When these are reduced, if one hopes to be able to see clear evidence of new physics (NP), it is crucial to have the theoretical error under control. In this paper, we show that, using a modification of the angular analysis currently used to measure phis^ccs in Bs -> J/psi phi, one can reduce the theoretical error due to PP. Theoretical input is still required, but it is much more modest than entirely neglecting the PP. If phis^ccs differs from the SM prediction, this points to NP in the mixing. There is also enough information to test for NP in the decay. This method can be applied to all Bs/Bsbar -> V1 V2 decays.