Flavour Physics

The detailed study of quark transitions provides insights into the structure of the Standard Model, and allows the discovery and study of physics beyond the standard model.

Precision flavour physics is sensitive to loop effects caused by particles that can be far heavier than those directly produced at colliders - it can see beyond the energy frontier. In the past, this approach resulted in the prediction of the charm quark, and a heavy top quark, well before colliders could produce these particles directly. The observation of CP violation led to the prediction of the entire third generation of particles even before the second one had been fully discovered, an achievement that has recently been rewarded with the 2008 Nobel Prize.

The Bristol Flavour Physics Group has a comprehensive flavour physics programme, covering B physics (LHCb), charm physics (CLEO-c) and kaon physics (NA62.) These areas complement each other in their sensitivity to New Physics, providing an unprecedented experimental precision where a whole host of New Physics models could become apparent. Bristol are the only group in the UK with such a far-reaching programme.

With the next generation of flavour physics experiments, we enter a completely new realm of New Physics sensitivity. We do not know which approach will discover evidence of New Physics first, the highly sensitive search for deviations from SM predictions in precision flavour physics at LHCb and NA62, or direct observation of new particles at CMS. However, it is certain that the input from both will be needed if we wish not merely to destroy the Standard Model, but to understand the physics that lies beyond it. The discovery and analysis of directly produced new, massive particles is the domain of CMS. The measurement of coupling constants, and access to mass-scales beyond those produced at the LHC, are the domain of flavour physics.

The group is at the forefront of analyses at LHCb. One of the most powerful ways to increase the New Physics sensitivity of the quark flavour sector is, paradoxically, to measure precisely the value of the Standard Model parameter γ using B±→DK± or B0→DK* decays.

The NA62 experiment at CERN will deliver physics that will complement the LHC data. The Bristol group is studying the rare decay K+→π+νν. By measuring this branching ratio to ten percent  the Standard Model will be tested decisively, or New Physics discovered. The large number of kaons at NA62 will allow other rare decays to be studied with unprecedented precision and searches for lepton flavour violation.

RICH Mirror
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