Study of rare B decays at ATLAS

Research Group: 
Particle Physics Research Centre
Number of Students: 
Length of Study in Years: 
Full-time Project: 
QM Scholarship
Project Description: 
The impressive progress that elementary particle physics made in the second half of the last century led to the formulation of a comprehensive theory, known as Standard Model (SM), which correctly describes all fundamental interactions in nature, except for the gravitational one. Indirect discoveries have always played an important role in high energy physics scenario and the indirect research can be considered to all intents and purposes complementary to the direct one since it allows to test much higher energy scales than those the current colliders are able to reach. This is very important now that electroweak precision tests and measurements on Flavour Changing Neutral Currents (FCNC) processes put very stringent constraints on physics beyond the SM, requiring it to appear first at scales O(10 TeV). On the other hand, New Physics (NP) is expected already at scales O(1 TeV) in order to offer a natural explanation to the smallness of the Higgs mass.

Rare B decays have always played a crucial role in shaping the flavour structure of the SM and particle physics in general. In particular, FCNC B decays, involving the semileptonic b-quark transition b to (s or d) provided crucial tests for the SM at the quantum level since they proceed through loop or box diagrams, and they are highly suppressed in the SM (also by helicity). Hence these rare B decays are characterised by their high sensitivity to NP. The Bs decay channel into two muons is the most direct example of the b to s transitions. At ATLAS we have analysed our data up to 2012, but we have now doubled our dataset hence a new analysis with new challenges and possibilities for further optimisation is starting. The ATLAS QMUL group has played a leading role in this analysis and under Dr Bona's supervision, a student could play a pivotal role in this effort.
SPA Academics: 
Marcella Bona