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Spectacular Physics from BaBar at ICHEP06

(Image - ICHEP06 poster)The major summer conference for particle physics, the 33rd International Conference on High Energy Physics (ICHEP06), began last Thursday morning in Moscow. Early last week, the usual frenzy of preparations at BaBar gradually subsided as the flood of physics results completed the internal review process, speakers finished up their talks and rehearsals, and the delegates sped off to Moscow. Just about everyone in the collaboration of 600 played an important role in these preparations, which rest foremost on the dedicated efforts of the PEP-II accelerator team and the BaBar operations crew. Satisfaction and excitement were running high. "We've been working day and night to finish up our summer results, complete the rigorous internal review of each, and then prepare the many talks," said BaBar Physics Analysis Coordinator Riccardo Faccini.

Even by BaBar standards, this year has been an unusually productive one. A total of 109 contributed papers are being submitted to the conference, up substantially from the 69 in 2004 and 72 in 2005. Of these conference contributions, the majority are final results: 69 papers have been or will be submitted to journals shortly. The remaining 40 contributions are fully developed analyses, which are ready for presentation to the wider particle physics community.

ICHEP06 follows the usual format for the Rochester series, with three days of parallel sessions held on Thursday through Saturday last week, followed by three days of plenary talks starting today. More than a thousand delegates to the conference have converged on Moscow for the most important gathering in particle physics this year. BaBar will highlight its many new physics results in 24 talks spread over six different parallel sessions, along with two plenary talks that were given earlier today in Moscow. "ICHEP06 is an opportunity to showcase the exciting science that is continuing to pour out of the B Factory experiments; it also is an outstanding forum for a new generation of talented young scientists to gain wider recognition in the particle physics community," said David MacFarlane, BaBar Spokesperson.

Planning and preparation for the summer 2006 campaign began almost a year ago with the September 2005 BaBar Collaboration Meeting. During the past year, BaBar has not only continued to accumulate new data at PEP-II, but has also undertaken a complete reprocessing of the existing data set. The new reconstruction implements improvements in the algorithms used to extract physics information from the raw event data and has resulted in a data sample with uniformly high quality for physics analysis. A new sample of simulated events was also produced and reconstructed over the past year, equivalent to three times the actual recorded number of events. "Reprocessing the full data sample and generating simulated events has been a massive but very successful world-wide effort over the past year, involving five Tier A computing centers in five countries and more than 40 simulation production sites throughout the collaboration," said Gregory Dubois-Felsmann, BaBar Computing Coordinator.

The outpouring of science from BaBar this summer spans the full range of physics questions being addressed with the B Factories. The overarching themes addressed with these results are providing an ever-improving precise understanding of the Standard Model for weak-interaction properties of quarks, a framework that then also allows us to search for evidence of new physics at high mass scales beyond the direct reach of current accelerators. "The scientific opportunity for discoveries of new physics at the B Factories remains very real and, ultimately, the legacy of precision flavor physics will prove extremely important throughout the era of the LHC as well," said MacFarlane.

These themes are reflected in the centerpiece suite of new BaBar measurements of CP violation or matter-antimatter asymmetries in B decays. A new measurement of CP violation in the most prolific channels, the same channels used in the original discovery of matter-antimatter differences in 2001, sets a precision benchmark for testing the Standard Model. Against this benchmark, new results for CP violation in B decay modes involving quantum loop diagrams, so-called penguin decays, allow us to search for evidence of new physics at high mass scales beyond the reach of current accelerators. New results for many penguin modes are being released this summer, including Bo η'Ko and a beautiful study of CP violation BoK+K-Kos where intricate interferences are possible. New results on the Unitarity Triangle angles α and γ have also been produced, including the first evidence for the rare decay Boρoρo, a critical element in precision measurements of α.

The same themes underlie a broad array of searches for very rare decays of beauty, charm and tau lepton decays. Indeed, many rare decays only occur through quantum loop processes, becoming windows for new physics. A beautiful new measurement of B decays to leptons and mesons containing no charm quarks demonstrates the rapid progress being made in pinning down a precise determination of the weak coupling between b and u quarks. Examples include the loop process Bργ, where BaBar has discovered a new mode and confirmed previous Belle results, providing yet another window for new physics searches. Tantalizing hints that we may be on the threshold for seeing matter-antimatter oscillations in states involving neutral charmed mesons are also reported. Observation of new particles, both within the spectrum of expected states and some new mysteries, are among the new results.

"I continue to be amazed by the breadth of exciting science coming out of BaBar. Each summer sees a fresh deluge of wonderful new results that manages to surpass the already copious production of the previous year. The B Factories continue to be a spectacular fountain of science," said SLAC Director Jonathan Dorfan.

—David MacFarlane
    SLAC Today, July 31, 2006