Ashutosh V. Kotwal
Fritz London Distinguished Professor of Physics
Professor in the Department of Physics
Prof. Ashutosh Kotwal's research focuses on the physics of fundamental particles and forces at high energies. The discovery of the Higgs boson has answered the 50-year old puzzle of how fundamental particles acquire mass. However, the properties of the Higgs boson are not understood, and neither is the process by which the Higgs field condenses everywhere in space. Prof. Kotwal is pursuing these questions experimentally using two approaches - precision measurements of fundamental parameters, and direct searches for new particles and forces.
Prof. Kotwal leads the worldwide effort to measure very precisely the mass of the W boson, which is sensitive to the quantum mechanical effects of new particles or forces. In particular it is directly connected to the properties of the Higgs boson. If the properties of the Higgs differ from the current Standard Model theory, the mass of the W boson will also differ from its predicted value.
Using the data from the CDF and D0 experiments, he has developed new experimental techniques for performing precise calibrations. He has published numerous measurements of the W boson mass with increasing precision, most recently achieving a precision of 0.02%. This was the world's best measurement, and it predicted the mass of the Higgs boson which is compatible with the measurement at the LHC.
He now leads the effort to further improve the precision to 0.01%, which can prove if other new particles exist. Since a fundamental scalar particle has never been found in Nature before, it is possible the Higgs boson is actually a composite particle containing constituents. Prof. Kotwal's W mass measurement is one of the most powerful methods to probe a new level of substructure in the Higgs sector.
Prof. Kotwal's research on the ATLAS experiment at the LHC is also motivated by the possibility of Higgs and top quark compositeness. He has initiated a new idea to search for top quark constituents by looking for top-antitop resonances in events with four top quarks. In this project he has been joined by colleagues from Harvard and DESY, Germany. He is also pursuing the vector boson fusion process as a method to measure important Higgs properties and to detect resonances in the Higgs sector, both providing incisive tests of the Higgs theory.
The second part of Prof. Kotwal's ATLAS research is motivated by Dark Matter, which was discovered on the galactic and cosmic scales via its gravitational interaction. If Dark Matter consists of particles, these may be produced from the decay of heavier, short-lived charged particles which in turn can be produced at the LHC. With his postdoc Kate Pachal and colleagues from Harvard and Genoa, Prof. Kotwal is designing an analysis to search
for heavy short-lived charged particles using the silicon pixel detector. This work is closely aligned with Prof. Kotwal's expertise in particle tracking and efforts to improve tracking algorithms for ATLAS. His group is working to improve both the efficiency and speed of these algorithms so that such rare signatures can be recognized and separated at very high rates. This project is a key component of the LHC upgrades to collect vastly more data over the next two decades.
Prof. Kotwal also works with his students, post-doc and collaborators on searches of rare, exotic signatures of new interactions. Searching for a fifth force on ATLAS, he wrote the first three ATLAS papers on searches for heavy force mediators decaying to leptons. On the CDF experiment he has published searches for charged and neutral gauge bosons mediating new weak forces, the Higgs boson in theories that extend the standard model, and excited states of standard model fermions. These particles are predicted in theories where the weak interaction has both left-handed and right-handed couplings (as is indicated by data on neutrino oscillations), in supersymmetric theories which impose a fermion-boson duality, and in grand unified theories. Also on CDF, Prof. Kotwal pursued improved techniques to search for the standard model Higgs boson, publishing three papers using advanced techniques. These techniques are now being used in the ATLAS experiment for the Higgs boson measurements in the vector boson fusion process.
Also on CDF, Prof. Kotwal and collaborators have published the most precise measurements of the top quark mass in the dilepton channel. His latest measurement used, for the first time in particle physics, neural network algorithms based on biological evolution. This method showed how to solve certain optimization problems based on ensemble properties.
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 has published a theoretical analysis of the production and decay of rotating black holes and their experimental signatures. Prof. Kotwal has also co-authored a paper on black hole relics.
Prof. Kotwal is the recipient of the Outstanding Junior Investigator Award and the Alfred P. Sloan Foundation Fellowship. He is a Fellow of the American Physical Society and a Fellow of the American Association for the Advancement of Science. He has served as project leader for analysis, software and computing on the CDF experiment, and as the head of the experimental particle physics research group at Duke. He served as the Chair of the Fermilab Users Executive Committee and the DPF Nominating Committee. He has served as the Chair of Duke University's Information Technology Advisory Committee and as the Associate Chair of the Physics Department. He received the Dean's Leadership Award from Duke University and was elected Fellow of the Maharashtra Academy of Sciences, India.
Research in High Energy Physics at Duke University awarded by Department of Energy (Co Investigator). 2013 to 2021
REU Site: Undergraduate Research in Nuclear Physics at TUNL/Duke University awarded by National Science Foundation (Senior Investigator). 2015 to 2019
W Boson Mass Measurement at CDF awarded by Department of Energy (Principal Investigator). 2013 to 2016
Fermilab Guest Appointment awarded by Fermilab (Principal Investigator). 2014 to 2016
Research in High Energy Physics at Duke University awarded by Department of Energy (Principal Investigator). 1991 to 2013
Duke Grant Supplement for US ATLAS Institutional Board Chair awarded by Department of Energy (Principal Investigator). 1991 to 2012
Research in High Energy Physics at Duke University awarded by Department of Energy (Co-Principal Investigator). 1991 to 2009
Hadron Collider Physics Conference awarded by National Science Foundation (Co-Principal Investigator). 2006 to 2007
Fellowships, Supported Research, & Other Grants
Aad, G., et al. “Measurement of azimuthal anisotropy of muons from charm and bottom hadrons in Pb+Pb collisions at sNN=5.02 TeV with the ATLAS detector.” Physics Letters, Section B: Nuclear, Elementary Particle and High Energy Physics, vol. 807, Aug. 2020. Scopus, doi:10.1016/j.physletb.2020.135595. Full Text
Aaboud, M., et al. “Measurements of top-quark pair spin correlations in the eμ channel at √s=13 TeV using pp collisions in the ATLAS detector.” European Physical Journal C, vol. 80, no. 8, Aug. 2020. Scopus, doi:10.1140/epjc/s10052-020-8181-6. Full Text
Aad, G., et al. “Search for a scalar partner of the top quark in the all-hadronic tt¯ plus missing transverse momentum final state at √s=13 TeV with the ATLAS detector.” European Physical Journal C, vol. 80, no. 8, Aug. 2020. Scopus, doi:10.1140/epjc/s10052-020-8102-8. Full Text
Aad, G., et al. “Search for direct production of electroweakinos in final states with one lepton, missing transverse momentum and a Higgs boson decaying into two b-jets in pp collisions at √s=13 TeV with the ATLAS detector.” European Physical Journal C, vol. 80, no. 8, Aug. 2020. Scopus, doi:10.1140/epjc/s10052-020-8050-3. Full Text
Aad, G., et al. “CP Properties of Higgs Boson Interactions with Top Quarks in the tt[over ¯]H and tH Processes Using H→γγ with the ATLAS Detector.” Physical Review Letters, vol. 125, no. 6, Aug. 2020, p. 061802. Epmc, doi:10.1103/physrevlett.125.061802. Full Text
Aad, G., et al. “Measurements of the production cross-section for a Z boson in association with b-jets in proton-proton collisions at √s = 13 TeV with the ATLAS detector.” Journal of High Energy Physics, vol. 2020, no. 7, July 2020. Scopus, doi:10.1007/JHEP07(2020)044. Full Text
Aad, G., et al. “Search for the HH → bb¯ bb¯ process via vector-boson fusion production using proton-proton collisions at √s = 13 TeV with the ATLAS detector.” Journal of High Energy Physics, vol. 2020, no. 7, July 2020. Scopus, doi:10.1007/JHEP07(2020)108. Full Text
Aad, G., et al. “Measurement of the transverse momentum distribution of Drell–Yan lepton pairs in proton–proton collisions at √s=13 TeV with the ATLAS detector.” European Physical Journal C, vol. 80, no. 7, July 2020. Scopus, doi:10.1140/epjc/s10052-020-8001-z. Full Text
Aad, G., et al. “Observation of the associated production of a top quark and a Z boson in pp collisions at √s = 13 TeV with the ATLAS detector.” Journal of High Energy Physics, vol. 2020, no. 7, July 2020. Scopus, doi:10.1007/JHEP07(2020)124. Full Text
Aad, G., et al. “Search for Heavy Higgs Bosons Decaying into Two Tau Leptons with the ATLAS Detector Using pp Collisions at sqrt[s]=13 TeV.” Physical Review Letters, vol. 125, no. 5, July 2020, p. 051801. Epmc, doi:10.1103/physrevlett.125.051801. Full Text
Yeh, C. H., et al. “Jet substructure variables with the SiFCC detector at 100 TeV.” Proceedings of Science, vol. 340, 2019.
Sen, S., et al. “Detectors for superboosted τ-leptons at future circular colliders.” Proceedings of Science, vol. Part F128556, 2016.
Yu, S. S., et al. “Study of boosted W-jets and Higgs-jets with the SiFCC detector.” Proceedings of Science, vol. Part F128556, 2016.
Hays, C., et al. “First Measurement of the W Boson Mass with CDF in Run II.” Journal of Physics: Conference Series, vol. 110, no. 2, 2008. Scopus, doi:10.1088/1742-6596/110/2/022019. Full Text