Raj Gandhi

Research Summary:

My research has mainly focussed on neutrino physics and the particle physics/ astro-physics interface.

Over the past year I have been actively involved along with several other physicists in writing and preparing a proposal for a planned Indian Neutrino Observatory (INO). With Anindya Datta, I have done detailed studies of the physics possibilities and potential of the INO detector.This work is ongoing, and currently Poonam Mehta, a student from Delhi University,Pomita Ghoshal and Srubabati Goswami are also actively contributing to the INO effort at HRI.

With A. Datta, Poonam Mehta and Uma Sankar, (hep-ph 0312027) we have shown that atmospheric neutrinos can provide a sensitive and robust probe of CPT violation (CPTV). We performed realistic event-rate calculations and studied the variations of the ratio of total muon to antimuon survival rates with L/E and L (L &equiv baseline length, E &equiv neutrino energy) in a detector capable of identifying the muon charge. We demonstrated that measurements of these ratios when coupled with the significant L and E range which characterizes the atmospheric neutrino spectrum provide a method of both detecting the presence of such violations and putting bounds on them which compare very favourably with those possible from a future neutrino factory.

With A. Datta, Pomita Ghoshal, Poonam Mehta, S Goswami and Uma Sankar, we are finishing a study of matter effects in the mu-tau oscillation probability.

With my student, Pomita Ghoshal, I am working on studies of the effects of muon polarization at neutino factories.

Publications:

• A. Datta, R. Gandhi, P. Mehta and S. U. Sankar, "Atmospheric neutrinos as a probe of CPT and Lorentz violation," arXiv:hep-ph/0312027.(to appear in Physics Lett B)

• R. Gandhi, K. Kar and S. Uma Sankar, "Working Group Report: Neutrino And Astroparticle Physics," Pramana {\bf 60}, 405 (2003).

Preprints:

• Matter effects in P_{&nu&mu&rarr &nu&tau} with A. Datta,P. Ghoshal, S.Goswami, P. Mehta and S. Uma Sankar, in preparation.

• Atmospheric Neutrino Physics Sensitivity studies for a Large Mass Iron Calorimeter, with A. Datta,P. Ghoshal, S.Goswami, P. Mehta and S. Uma Sankar, in preparation.

Invited Talks and Seminars:

May 12, 2003	Invited Plenary talk at the International Conference on TRENDS IN NEUTRINO PHYSICS, Argonne National Labs, Chicago.
May 6, 2003	Invited talk at PHENO 03, Symposium on High Energy Particle Phenomenology, Madison, Wisconsin.
May 24, 2003	High Energy Seminar, Brookhaven National Lab, New York.
April, 2004	Invited Plenary talk at the Conference on PERSPECTIVES IN PARTICLE PHYSICS AND COSMOLOGY, PRL, Ahmedabad

Other Activities:

Teaching and Mentoring Activity: I have taught the Quantum Mechanics course for first year students in Fall 2003. I am guiding Pomita Ghoshal towads her Ph.D. In addition, Poonam Mehta, a PhD student from Delhi University, has been closely working with me over the past 2 years and we have written several papers together.

I continue to be closely involved in INO work. I am on the Programme Management Committee for the project, and have regularly participated in meetings and decision making. In addition, I am Co-ordinator for the Physics subgroup of the Collaboration, which is responsible for the physics part of the project. At present we are writing the physics chapter for the Detailed Project Report which will shortly be submitted to the funding agencies and become a INO public document.

Finally, I have convened and/or served on institute committees.