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In this issue:
From the Theory Group: Could Quarks and Leptons Be Supersymmetric Bound States?
SLAC Blood Drive November 17

SLAC Today

Thursday - November 11, 2010

From the Theory Group: Could Quarks and Leptons Be Supersymmetric Bound States?

(Image - preons)
 (Image courtesy Gonzalo Torroba.)

The Standard Model of particle physics has been extremely successful in describing the interactions and behaviors of subatomic particles, but many important puzzles remain. One mystery is the origin of the masses for particles called quarks, which make up protons and neutrons, and leptons, of which the best known is the electron. These masses vary widely; for example, the lightest quark, the "up" quark, is lighter than the heaviest quark, the "top" quark, by a factor of 100,000. The Standard Model does not explain the mass ratios between quarks and leptons. Leading theories of physics beyond the Standard Model, such as the popular theory of supersymmetry, also do not address this question.

In the weak interactions of the Standard Model, also called the weak nuclear force, interrelationships between the various quarks have been found to correspond to entries in a model called the Cabbibo-Kobayashi-Maskawa matrix. These matrix entries follow an intricate pattern related to the quark masses. However, the Standard Model does not explain the origin of this matrix, and so does not explain the mass ratios between the quarks or why they show the decay patterns observed in particle experiments. Leading theories of physics beyond the Standard Model, such as the popular theory of supersymmetry, also do not address these questions.  Read more...

SLAC Blood Drive November 17

The SLAC Blood Drive is coming next Wednesday, November 17, from 8:00 a.m. to 3:30 p.m. in the Panofsky Auditorium lobby. Each donor will receive a special edition Donor Cup 2010 T-shirt. Bring a first-time donor with you and each of you will receive a Baskin Robbins "Pint for a Pint" coupon!

Remember: we are still in competition with many tech companies in the Bay Area for the 2010 Blood Drive "Donor Cup." Our numbers look great and hopefully they will increase as we go forward.

To make an appointment, visit bloodcenter.stanford.edu and click on "Schedule a Blood Drive." Search by sponsor code: 0136.

Walk-ins are welcome. Appointments will be given priority. For eligibility questions, see "Eligibility, Medical History, and Deferral Information." For more information, please contact Lauren Barbieri (x2354).

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