High Energy Physics Seminar: Dr. Nirmal Raj, University of Notre Dame  Add To Calendar

  • Date(s): Wednesday, 9/28 11:00 AM to Wednesday, 9/28 12:00 PM
  • Speaker: Dr. Nirmal Raj
  • Host: James Unwin
  • Campus Address: 2214 SES (Science and Engineering South)

Title:  Anticipating New Physics in Dilepton Angular Distributions.

Abstract: Hunting for resonances in invariant mass or momentum distributions is an important programme at the LHC. The location and size of a peak in the spectrum give a clear indication of the particle mass and decay width. Subsequent measurements of angular spectra can further inform us of the spin and chiral couplings. However, new physics may be non-resonant, in which case both halves of the final state phase space -- spectra of both energies and angles --  may be needed to extract its mass, spin and coupling properties all at once. Here the first hints may possibly appear in angular spectra. A good testing ground for this possibility is the Drell-Yan process of dilepton production, due to its high rates and small uncertainties. In this talk, I will corner the parameter space of leptoquarks (LQs) using LHC measurements of dilepton invariant mass spectra and the forward-backward asymmetry (AFB). The limits obtained are often stronger than those from dedicated searches through LQ production. I will also show that the AFB measurement could anticipate LQs sooner than any other probe. I will conclude with some suggestions on angular observables that may provide an unambiguous interface between theory and experiment.

HEP Sep28 flyer