Physics Analysis Activities in Group B
Studying the physics of CP violation; in particular, participation in the first studies of CP violation in the heavy quark B meson system, and in data analyses leading towards an understanding of the forces responsible for the matter-antimatter asymmetry in our universe. Specifically, the group has leadership of a study of inclusive particle production and the specifics of hadronization of the B quark. Members of the group have important leadership roles in studies of rare B decays, in systematic studies of radiative decays and in using BaBar data to measure R, the ratio of the e+e- total hadronic cross section to the Upsilon(4S) pair cross section. The group is also involved in long-term studies to measure CP violation in rare B decays (B -> Phi K).
Inclusive Spectra Analysis Working Group (AWG)
Conveners: Dave Muller and Blair Ratcliff (SLAC Group B)
There are two broad topics of study.
- The measurement of the fragmentation of the heavy b quark through
determination of the momentum distribution and relative rates of
inclusive particle production at the upsilon 4S.
- A study of events in which the upsilon 4S state, created in the initial PEP II electron-positron collisions, breaks up into a hard radiative photon and a recoiling hadronic system. A survey of the light quark spectroscopy in this recoiling system is proving interesting. But more topically interesting, these events can be used to provide a precise measurement, (~2-5%), of the ratio R=(e+e- -> hadrons/ e+e- -> µ+ µ-) over the energy region from about 500 MeV up through 4 or 5 GeV. Such a measurement would allow the determination of the QED running coupling constant, a, which is an increasingly important quantity in precision Electro-Weak Symmetry Breaking tests, especially in the current (g-2) experiment at BNL.
Radiative B Decays AWG
This group is responsible for measuring decays of the type b -> s gamma, b -> d gamma, and b -> s l+l-. This includes B decays such as B -> K* gamma, rho gamma, omega gamma as well as inclusive b -> s gamma. The former provides important information on the CKM triangle by constraining the length of the ratio vtd/vts. The latter provides constraints on New Physics that are, in some cases, more powerful than what can be achieved at the highest energy colliders planned.
Study of Rare B Decays
The study of B -> Phi+K0S is a charmless decay that we expect to be dominated by gluonic penguin diagrams and should have the same CP violating phase angle, sin2ß, as the classic golden decay B -> J/Psi + K0S. Differences in the angle measured in these two decay modes would indicate new physics! Currently the Standard Model is looking good, but we look forward to accumulating statistics and increasing the precision of the Phi+K0S measurement, looking for cracks in the Standard Model.
The research team currently consists of:
Dr. David Aston, Jose Benitez, Dr. Mark Convery, Dr. William Dunwoodie, Bryan Fulsom, Prof. David W.G.S. Leith, Matt McCulloch, Dr. David Muller, Dr. Blair N. Ratcliff, and Dr. Jaroslav Va'vra.
Graduate Student Contact
We currently offer research opportunities for
new Stanford physics graduate students to join in our work
under the supervision of Prof. Leith and Dr. Ratcliff.
Please refer to the group B research opportunities page for details on those and other research opportunities available in group B.
Interested physics students are invited to explore these opportunities further by contacting us for an appointment.