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In this issue:
BaBar Delivers for Winter and Spring Conferences
Science Today: BaBar - Taming Theoretical Errors in a Quark Mixing Parameter
Please Be Alert to Caution Zones
Photo: Under Secretary of Energy David Garman Visits SLAC

SLAC Today

Thursday - March 23, 2006
(Image - BaBar Collaboration)
The BaBar Collaboration

BaBar Delivers for Winter and Spring Conferences

by Heather Rock Woods

BaBar collaborators are hard at work preparing a new round of the latest physics results for the winter conferences. All told some 50 new papers have been produced or are in the final stages of review.

The "season" started in Aspen in mid-February, includes three major European conferences, and concludes in mid-April in Vancouver at the Flavor Physics and CP Violation conference.

BaBar's main mission is CP violation in B meson decays—responsible for differences in the decays of matter versus antimatter. The B-Factory program is much richer, though, with BaBar serving as an excellent factory for other particles as well: charm mesons, tau leptons, and charmonium mesons. Read more...

(Daily Column - Science Today)

BaBar: Taming Theoretical Errors in a Quark Mixing Parameter

by Heather Rock Woods

One of the main goals of the BaBar experiment is to make precision measurements of the elements in the quark mixing matrix involving the b quark. Also known as the CKM matrix after its inventors, quark mixing describes how the various quarks transform from one species to another, with elements that relate the weak interaction to the origin of mass.

Recently, the BaBar experiment published a precision measurement of the magnitude of the smallest CKM matrix element, Vub. Using a novel approach, the researchers greatly improved the theoretical error for the measurement, bringing it down from nine percent to six percent. In the same article, another method produced a result with only a three percent theoretical error, but at the price of a significant loss in statistical sensitivity. This second approach will require a lot more data to be competitive, but is considered to be the prototype measurement for what will ultimately be the most precise approach in the future.

A precision measurement of Vub allows physicists to predict the scale of the asymmetry in matter and antimatter decays in neutral B mesons within the CKM picture of the weak interaction. It also is part of set of rare decay measurements that may give us an early hint, or certainly will tell us indirectly about the underlying nature, of any new particles that may be directly produced at the Large Hadron Collider now under construction at CERN.

Please Be Alert to Caution Zones

by Larissa Williams

(Photo - Construction Zone)

SLAC is a busy site, with many science and research projects going on at all times. To support this research, we also have ongoing construction and maintenance projects to upgrade existing structures and create new ones. The work zones are constantly shifting, so precautions in the form of barricades, yellow or red tape, orange cones, and other methods are used to alert people of hazards.

Recently, pedestrians and bicycle riders have crossed areas blocked with hazard tape, and in a couple of cases, even continued on when asked not to by safety personnel. The area near the new Kavli building has been particularly problematic as parts of the building have been opened for use, while the walkway near one of the entrances is still under construction. This is a dangerous situation. Please be aware of the hazards ongoing in these areas and heed construction signs.

Safeguards and Security at SLAC has issued a reminder that any areas at SLAC that are blocked off or marked with yellow caution tape or red danger tape should not be entered or crossed by any pedestrian or vehicular traffic.  Read more...

Under Secretary of Energy David Garman Visits SLAC

(Photo - Garman)

Under Secretary Garman attended the DOE Site Offices Meeting and toured the SLAC site with Jonathan Dorfan yesterday. Garman visited SSRL, BaBar and GLAST.  He also discussed ILC and the LCLS project.  Here he is seen with Doug Schwartz and Keith Hodgson.

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