• The search for physics beyond the Standard Model which until now has explained all interactions between the elementary particles, is an important area of research.
• Now, there is evidence that the Standard Model is not a complete description of the microscopic world of elementary particles.
• Scientists at Institute of Mathematical Sciences (IMSc), Chennai, have come up with a calculation based on the observations made at the LHCb (Large Hadron Collider beauty) experiment at CERN, which shows definitively that in a specific interaction, the standard model predictions are violated and there is indirect evidence of new physics.

B meson, lighter boson, vector-Kaon meson & a pair of muon:

• The interaction that has been studied involves the decay of the B meson into a lighter boson called the vector-Kaon meson and a pair of muon (a heavier cousin of the electron) and its antiparticle.
• The process is interesting as it involves a change in a quantum number known as “flavour” without the change of charge.
• The process can happen only because of the quantum nature of elementary particles and involves virtual creation of heavier particles for a very short time — a process known as the loop diagram.

loop processes:

• loop processes themselves are very tiny in relation to louder signals from more dominant processes.
• Flavour-changing loop processes like this one are further suppressed because of the nature of flavour-changing neutral current involved.
• Because of this weakness of the signal, the process is sensitive to violation of the Standard Model.
• Rusa Mandal and Rahul Sinha of IMSc, Chennai, have pointed out the precise discrepancy that shows up when the theoretical calculation based on the Standard Model is compared with the precise experimental observations from the LHCb at CERN.

First mooted:

• “It was at IMSc in 1996 and 1999 that we first showed how this mode would allow a plethora of related observables to be measured allowing for a very sensitive search for new physics,” .
• “Today, the study of this mode attracts the most attention among physicists studying flavour-changing loop processes and is a focus at all major high energy physics conferences in the world.”

Importance:

• Identification of this mode of decay as the one that would show up new physics has resulted in many physicists around the world studying it.