CHARM: MIXING, CP VIOLATION AND RARE DECAYS AT LHCb

Michael Alexander,On Behalf Of The Lhcb Collaboration

doi:10.1142/s2010194514604141

Michael Alexander, On Behalf Of The Lhcb Collaboration

Open Access

https://doi.org/10.1142/s2010194514604141

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Abstract

Recent results on mixing, CP violation and rare decays in charm physics from the LHCb experiment are presented. Study of "wrong-sign" D0 → K+π- decays provides the highest precision measurements to date of the mixing parameters x′2 and y′, and of CP violation in this decay mode. Direct and indirect CP violation in the D0 system are probed to a sensitivity of around 10-3 using D0 → K+K− and D0 → π+π− decays and found to be consistent with zero. Searches for the rare decays [Formula: see text], [Formula: see text] and D0 → μ+μ− find no evidence of signal, but set the best limits on branching fractions to date. Thus, despite many excellent results in charm physics from LHCb, no evidence for physics beyond the Standard Model is found.

Highlights

CP violation and the branching fractions of rare decays in charm physics can be significantly enhanced beyond Standard Model (SM) predictions by the presence of non-SM particles
These are distinguished by a fit to the distribution of mD0 and ∆m ≡ mD∗+ − mD0
Where ACP is the time-integrated CP asymmetry of the given decay, gives direct access to direct CP violation as the production asymmetry of the D0 meson cancels in the difference

Summary

Introduction

CP violation and the branching fractions of rare decays in charm physics can be significantly enhanced beyond Standard Model (SM) predictions by the presence of non-SM particles. Precision measurements of these parameters can provide evidence for, or strict limits on, new physics. The LHCb detector at the LHC is designed for precision measurements of CP violation in decays involving c and b quarks. The Vertex Locator provides fine tracking around the interaction point, achieving decay-time resolutions of around 50 fs for D0 mesons; the full tracking system yields momentum resolutions of σ(p)/p ∼ 0.5%; and the two Ring Imaging Cherenkov detectors provide clean separation of pions and kaons.

TeV in and

Rare Decays

Conclusions