Office Location: 281 Physics
Office Phone: 919-660-2563
Email Address: kotwal@phy.duke.edu
Web Page: http://www.phy.duke.edu/~kotwal
Research Categories: Experimental High Energy Physics
Research Description:
Prof. Ashutosh Kotwal's research focusses on the physics of fundamental particles and forces at high energies. One of the outstanding mysteries is the mechanism by which particles acquire mass. The theory of gauge symmetry has been very successful in describing the known fundamental forces; however this theory is obviously incomplete because it requires all particles to be massless. Clearly we are missing a big piece of the puzzle.
Prof. Kotwal is pursuing this question experimentally using two approaches - precision measurements of fundamental parameters, and direct searches for new particles and forces. He is the convener of the Electroweak physics group in the CDF experiment at Fermilab. The experiment is collecting data from proton-antiproton collisions with a total energy of 2 trillion eV (equivalent to accelerating potential of 2 trillion volts), the highest energy collider in the world. Physicists in this group are engaged in precision measurements of the production and decay properties and the self-interactions of the W and Z bosons and the photon.
Prof. Kotwal leads the effort to measure the mass of the W boson, which is sensitive to the quantum mechanical effects of new particles or forces. He has developed a new experimental technique of finding and using cosmic rays for precise calibrations. With the data to be collected over the next few years, his goal is to make a W mass measurement with a precision of 0.03%, a major improvement over the state-of-the-art.
Prof. Kotwal also works with his students and post-doc on searches of rare, exotic signatures of new interactions. He recently published the results of a search for a new weak force and particle substructure, which is the most sensitive search in the electron-neutrino channel. His student, Heather Gerberich, is completing her Ph.D. thesis on a search for new, electron-like particles decaying to an electron and a photon. Such states are predicted by particle hypotheses as tightly-bound states and in theories of unified forces. She presented her results at the APS Conference this year and will also be presenting them at the Lepton-Photon Conference. Dr. Kotwal is also working with an undergraduate student, Edward Daverman, to perform a similar search for massive muon-like states decaying to a muon and a photon. These heavy lepton searches are the first performed at Fermilab.
Prof. Kotwal is working with his post-doc, Christopher Hays, and another graduate student, Joshua Tuttle, to search for doubly-charged Higgs particles. These particles are predicted in theories where the weak interaction has both left-handed and right-handed couplings, as is indicated by recent data on neutrino oscillations. Furthermore, in Supersymmetric extensions which impose a fermion-boson duality, the doubly-charged Higgs particle is predicted to be light, providing exciting motivation for the search. Chris presented these and other exotic search results at the Annual Fermilab Users Meeting this year. The cosmic ray detection technique mentioned above provides crucial input that makes these searches possible.
In addition to his experimental research, Prof. Kotwal has done theoretical work in the phenomenology of black holes in extra spatial dimensions. Extra spatial dimensions have been motivated by string theory and to explain why the gravitational force is so much weaker than the electromagnetic force at large distances. In this scenario it is possible for the gravitational force to be strong in the high energy regime of particle colliders, leading to the production of black holes. Prof. Kotwal and his post-doc published a paper last year, which analyses the production and decay of rotating black holes, and describes their experimental signatures. Prof. Kotwal has also co-authored a paper on black hole relics with colleagues from J. W. Goethe University in Frankfurt, which was published this year.
Dr. Kotwal is the recipient of the Outstanding Junior Investigator Award and the Alfred P. Sloan Foundation Fellowship.
Teaching (Fall 2009):
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