Roy Briere-Dept of Physics - Carnegie Mellon University

Roy Briere

Professor, Physics

Office: Wean 7418
Phone: 412-268-2742
Fax: 412-681-0648


Ph.D., University of Chicago


My research field is high-energy particle physics.  I am interested in "flavor physics" as well as other topics.  Flavor physics is the study of the decays and other properties of the different types (or flavors) of quarks.  The weak interaction, which is responsible for these decays, has several unique features, including the violation of discrete symmetries such as parity (mirror reflection) and CP (combined parity and matter-antimatter inversion).  In addition, it is the only force which results in a change of particle type upon emission of one of its force carriers, the W boson.  As such, it is responsible for all fundamental decays.

My main activity involves the BESIII experiment at the BEPCII collider in Beijing.  Electron-positron collisions are used to produce various bound states of charm quarks.  I joined in 2008, shortly before first data-taking, along with several other US colleagues with the aim of focusing on charm physics via weak decays of D mesons.  Many key measurements needed for progress in flavor physics, such as decay constants, semileptonic form factors, and absolute hadronic branching ratios, can be made by our experiment.  Key results will be compared with modern Lattice QCD.  In many cases, our goal is to validate the LQCD results in the charm sector to give confidence in other LQCD results.  These other calculations are a critical input to interpretations of already existing data about
bottom quark decays, but are not easy to directly validate as they are in the case of charm.  The world's best charm results are from CLEO (another experiment I collaborate on), but greater precision is desirable to perform even more stringent tests. 

In 2013, I joined the BelleII experiment at the KEK Lab in Japan.  This is a second-generation "B factory" operating in the 10 GeV energy range to study topics such as CP violation and rare B decays.  Many other topics, including charm physics, are also accessible.  We plan to accumulate a data sample 50 times larger than previous experiments.

My interest in flavor physics stems from my Ph.D. research measuring CP violation and performing tests of CPT symmetry (CP plus reversal of time flow) in the neutral K meson system, involving weak interactions of strange quarks.  Since 1995, I have been a member of the CLEO collaboration, which also used electron-positron collisions to study bottom and charm quarks. Data-taking finished in 2008, and while final results are still being extracted, my focus is now shifting toward extending key CLEO results at BESIII. 

In addition to physics analysis, other interests include calibration of wire drift chambers (both for tracking and for dE/dx particle identification), and work on other software infrastructure, particularly "D Tagging" tools.  I also served as CLEO's co-spokesperson from 2005-7, and earlier as CLEO Analysis Coordinator.

Selected Publications