• Research areas: High Energy Physics and Experimental Cosmology
  • Education: Ph.D.: Princeton Univ. (2002)
      M.A.: Princeton Univ. (1999)
      A.B.: Harvard Univ. (1996)

My research attempts to find answers to the following two questions:
  1. "Why is the universe predominantly made of matter (rather than equivalent amounts of matter and antimatter)?"
  2. "Why does the expansion of the universe appear to be accelerating?"
In order to answer these two fundamental open questions in physics, I work on two experiments: BaBar and SNAP.

On BaBar, we study the phenomenon of CP violation. CP (or charge-parity) violation is a property of the Standard Model of particle physics, and is observed when particles decay via just one of the 4 known physical forces: the weak interaction. As the physicist Andrei Sakharov showed in 1967, CP violation is necessary for a matter-antimatter asymmetry to develop in the early universe after the Big Bang. However, there is not enough CP violation in the Standard Model of particle physics to explain why the universe we observe today is made of matter. Thus we have the question of where the extra CP violation could occur. This is one of physics' major unanswered questions. My colleagues and I specifically search for CP violation in decays of bottom quarks to the triplet of quarks: c anti-c d. This process is observable at the BaBar detector at the Stanford Linear Accelerator Center near Palo Alto, CA. This process is especially sensitive to potential sources of CP violation from extentions to the Standard Model at high energies which could help explain the asymmetry of matter and antimatter in the universe.

Come and talk to me anytime if you're interested in working on a physics project, if you have any general physics questions, or if there's anything else I could help you with.


Measurement of the Branching Fraction and CP content for the Decay B0 -> D*+D*-
Accepted for publication in Physical Review Letters (June 2002)

Links to other BaBar publications (authored by the BaBar collaboration, including myself)

Other members of the Caltech BaBar group:

Prof. David Hitlin
Prof. Frank Porter
Dr. Anders Ryd
Dr. Gregory Dubois-Felsmann
Dr. Songhoon Yang
Dr. Ilya Narsky
Alex Samuel
Ed Chen
Alexei Dvoretskii

In addition to BaBar, I have also recently joined the SNAP collaboration, which is in search of an answer to the second question above, namely: Why does the expansion of the universe appear to be accelerating? The problem has links to the interaction of quantum mechanics and Einstein's general relativity. Little is known about how how these two theories reconcile with each other, especially in terms of experimentally testable predictions, and information in this area has the enticing chance of pointing in the direction of the long-awaited goal in physics: a unified theory of quantum gravity which can be verified experimentally. My interests on this experiment include measurement of large-scale structure using weak lensing and measurement of spatial and time derivatives of the "dark energy" that is apparently causing the universe to undergo accelerated expansion.


The SNAP experiment and collaboration

Other members of the Caltech SNAP group:

Prof. Richard Ellis
Dr. Alexandre Refregier

NOTE TO STUDENTS: I am especially interested in any ideas or questions about physics you may have. If you happen to have a question from any area of physics to which a search has not led to an answer, please come by (Lauritsen 363) anytime or send me an e-mail -- I would be very happy to help you try to answer it (if it has an answer). I am especially interested in any potentially new ideas about physics you have, and helping you find out if your ideas have been thought of before and if they are correct.

Justin Albert ---