A new chapter in the story of B decays

Observing something may begin a story, but the subsequent study fills in the rest of the book.

The observation of a new particle or a new decay mode is not the end of a story, but the beginning of one. New chapters must follow as the properties of the phenomenon are studied and their measurements refined.

Earlier this year, the LHCb collaboration opened the book on a new decay mode for the neutral Bs meson, a pairing of a bottom quark and a strange quark. Sometimes, the final decay products include two charged K mesons, particles containing an up and a strange quark. The newly observed decay mode arises when the K+ and K mesons are being produced by a more massive intermediate state than usual. A recent analysis at DZero verifies this observation and provides the next chapter in the story of this decay mode.

The decays of neutral B mesons are interesting because they allow for direct tests of matter-antimatter asymmetry. By independently verifying this decay mode, DZero has confirmed that there is an additional means to test for differences in the behavior of matter and antimatter. The K+ and K can also be used to directly study the massive intermediate state that produced them. The DZero analysis measured the neutral Bs meson’s decay rate into this intermediate particle. Analyzers also studied the spin of the intermediate particle, verifying that the particle is consistent with being a spin-2 particle, as suggested by the initial observation, and further ruling out the spin-0 and spin-1 states.

By not simply confirming the initial observation but performing complementary measurements and constraining the properties of the intermediate particle, DZero has contributed an exciting chapter to the ongoing story of this newly observed decay mode.

Mike Cooke

These physicists made major contributions to this analysis.
What if five or 10 years in the future, a similar observation is made that the Tevatron data should be able to confirm? The DZero data preservation task force recently issued a report describing the steps that need to be taken to ensure that such analyses can be performed in the future.