High Energy Physics

The High Energy Physics group at the University of Louisville is concerned with fundamental questions about the basic structure of matter and its interactions. We ask why the visible universe seems to be dominated by ordinary matter (where has the anti-matter gone?), why are the masses of the particles in nature what they are, and how do the interactions among these particles help shape the universe? Do particles undergo heretofore unexpected interactions and what new information can we gain about the universe by studying such rare processes? In particular, we study the production of particles collectively referred to as hadrons in an attempt to better understand the strong nuclear force, and we contribute to a search for the first evidence of the direct conversion of a muon to an electron.

We are members of the BaBar Collaboration and in the process of joining the Mu2e Collaboration. The BaBar detector collected data from 1999 to 2008 in electron-positron collisions at the SLAC National Accelerator Lab in California. Mu2e is in the early stages of planning and construction at FermiLab near Chicago, IL. One of our faculty members (Brown) was also recently a visitor on the ATLAS experiment. ATLAS began taking data in late 2009 with proton-proton collisions at the Large Hadron Collider (LHC) of the European Organization for Nuclear Research (CERN - which stands for the French "Conseil Europeen de Recherche Nucleaire"). BaBar produced copious high-quality data that we will continue to analyse for many years. ATLAS is producing abundant high-quality data for analysis and discovery over the coming decades. Mu2e will produce plentiful high-quality data in a few years and will provide unprecedented sensitivity for very rare processes.

Babar is a large, general-purpose electron-positron collider detector operating at center of mass energies near 10 GeV. The experiment ran in the PEP-II storage rings at SLAC in "B-Factory" mode, meaning that it was tuned for optimal production of the B meson, a particle whose decays provide an excellent glimpse at matter-antimatter asymmetry. Currently, the University of Louisville group is investigating probes of QCD in quark and gluon jets, studying inclusive hadron production, and searching for rare CP-violating decays of the B-meson to final states with baryons. This work involves extensive software development. The group has been steadily involved in software development and administration on BaBar since 1996. (Brown, Banerjee, Davis).

On ATLAS, we assisted with simulations of radiation backgrounds that affect the detector. The work resulted in some improvements to shielding design, reducing contamination from background radiation in sensitive detector systems. (Brown, Banerjee)

Mu2e is in development and the early stages of construction. The experiment uses a unique axial magnetic gradient and 'S-shaped' beam line to transfer muons to an aluminum target where they are captured. Subsequent conversion of the muon to an electron will result in the electron being jettisoned from the aluminum target and detected. This is a very sensitive measurement which calls on the experimental team to control and understand possible backgrounds. The University of Louisville group is helping primarily with software development and simulation. (Brown)

Faculty

• Swagato Banerjee, Ph.D. (Tata Institute of Fundamental Research, Mumbai, India)
• David N. Brown, Ph.D. (Purdue University)
• Christopher L. Davis, Ph.D. (Oxford University)

Representative Publications

• Search for a dark photon in e⁺e^- collisions at BABAR, J.P. Lees, D. N. Brown, C. L. Davis et al. (BABAR Collaboration), Phys. Rev. Lett. 113, 201801 (2014)
• Antideuteron production in Υ(nS) decays and in e⁺e^- → qq at 10.58 GeV, J.P. Lees, D. N. Brown, C. L. Davis et al. (BABAR Collaboration), Phys. Rev. D 89, 111102(R) (2014)
• Evidence for the baryonic decay B⁰ → D⁰ Λ Λ, J.P. Lees, D.N. Brown, C.L. Davis et al. (BABAR Collaboration), Phys. Rev. D 89, 112002 (2014)