Upsilon(5S)

Sorry for not writing for long time. I was busy for the analysis for summer conferences. Maybe I should look back what happened.

KEKB accelerator stopped its operation in the end of June for summer shutdown. Actually, we have to stop the accelerator during summer, in order to save electric power. In Japan, summer is the season when people use a large amount of the electricity. We will resume the experiment on September.

Before we stop the operation, we took some data at Upsilon(5S) resonance. Usually, the energy of KEKB is adjusted to Upsilon(4S) to produce B mesons (e+e- -> Upsilon(4S) -> BB). But this time, some collaborators requested to take at Upsilon(5S) for feasibility study for Bs mesons.
The study of Bs (Bs mixing, rare Bs decays ...) is now ongoing at Tevatron, and will be planned at LHC. But, KEKB/Belle can also provide some interesting physics if it runs at Upsilon(5S). The problem is that Upsilon(5S) does not necessarily produce Bs mesons (B* etc. are also produced), so I don't know how difficult the analysis is.

The Upsilon(5S) data is still under process, but will be available soon, so we might see some results in near future.