Resonances gone topsy turvy - the charm of QCD or new physics in b→sℓ+ℓ−?

James Lyon, Roman Zwicky

Research output: Contribution to journalArticle

Abstract

We investigate the interference pattern of the charm-resonances Ψ(3370,4040,4160,4415) with the electroweak penguin operator O9 in the branching fraction of B+→K+μμ. For this purpose we extract the charm vacuum polarisation via a standard dispersion relation from BESII-data on e+e−→hadrons. In the factorisation approximation (FA) the vacuum polarisation describes the interference fully non-perturbatively. The observed interference pattern by the LHCb collaboration is opposite in sign and and significantly enhanced as compared to the FA. A change of the FA-result by a factor of -2.5, which correspond to a 350%-corrections, results in a reasonable agreement with the data. This raises the question on the size of non-factorisable corrections which are colour enhanced but loop-suppressed. In the parton picture it is found that the corrections are of relative size ~-0.5 when averaged over the open charm-region which is far below -3.5 needed to explain the observed effect. We present combined fits to the BESII- and the LHCb-data, testing for effects beyond the Standard Model (SM)-FA. We cannot find any significant evidence of the parton estimate being too small due to cancellations between the individual resonances. It seems difficult to accommodate the LHCb-result in the standard treatment of the SM or QCD respectively. In the SM the effect can be described in a q2-dependent shift of the Wilson coefficient combination Ceff9+C′eff9. We devise strategies to investigate the microscopic structure in future measurements. We show that the charm-resonance effects can accommodate the B→K∗ll-anomalies (e.g. P′5). Hence our findings indicate that the interpretation of the anomaly through a Z′-boson, mediating between bs and ll fields, is disfavoured. More generally our results motivate investigations into b→sc¯c-physics.
Original languageEnglish
Number of pages28
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Publication statusUnpublished - 3 Jun 2014

Keywords

  • hep-ph
  • hep-ex

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