RAMANUJAN FELLOWS

K.NARAYAN Associate Professor, Physics Chennai Mathematical Institute Plot H1, SIPCOT IT Park Padur PO Siruseri-603103, Tamil Nadu [email protected]

K. Narayan obtained his B.Tech. (Engineering Physics) in 1997 from IIT Bombay, Mumbai, India, and his Ph.D. (string theory) from Cornell University, Ithaca, USA. After postdoctoral work at the Center for Geometry and Theoretical Physics, Duke University, USA, and the Tata Institute of Fundamental Research, Mumbai, India, Narayan joined the Chennai Mathematical Institute, Siruseri, India, as physics faculty in August 2007.

RESEARCH DESCRIPTION My research area is string theory, perhaps the most promising attempt at understanding the fundamental principles involved in unifying quantum mechanics and general relativity (gravity). I am broadly interested in string theory and its implications for physical phenomena in particular pertaining to the early universe, many body physics, spacetime geometry and quantum field theory. Some of the most important developments in string theory over the last several years have involved the remarkable connections between gravitational theories and quantum field theories without gravity, dubbed as “holography” (also known as AdS/CFT duality). In recent times, there has been considerable interest in generalizations of these to nonrelativistic systems towards addressing questions in many body physics. Some of my recent work has to with understanding some of these models (in particular involving Lifshitz scaling) concretely within string theory. This is a fascinating and exciting area currently and I'm continuing to explore this further. Some of my other interests involve studying Big-Bang (cosmological) singularities both in the context of certain time-dependent generalizations of AdS/CFT, and by studying the excitation spectra of strings. These toy models reveal new perspectives on these questions on the origins of the universe and time in the vicinity of the Big-Bang, which are under investigation. The study of instabilities in spacetime (in the absence of supersymmetry) is fascinating and string theory gives powerful tools to study the endpoints of such instabilities and the resolution of possible singularities. In many cases, the study of stringy excitation modes (in particular, closed string tachyons) dovetails beautifully with the algebraic geometry description of singularities present, enabling a description of phenomena such as topology change: some of my work has explored these connections. I have also been interested in the study of charged excited states in gauge theories, in particular their internal structure and possible decay in certain regimes, as well as enumeration of their degeneracies, using their realizations in string theory.

SELECTED PUBLICATIONS K.Narayan, On Lifshitz scaling and hyperscaling violation in string theory, arXiv:1202.5935 [hep-th]. Koushik Balasubramanian, K. Narayan, Lifshitz spacetimes from AdS null and cosmological solutions, J. High Energy Phys. 1008:014 (2010), arXiv:1005.3291 [hep-th].

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K. Narayan, On nonsupersymmetric C4/ZN, tachyons, terminal singularities and flips, J. High Energy Phys. 1003:019 (2010), arXiv:0912.3374 [hep-th]. Kallingalthodi Madhu, K. Narayan, String spectra near some null cosmological singularities, Phys. Rev. D 79, 126009 (2009), arXiv:0904.4532 [hep-th]. Adel Awad, Sumit Das, Suresh Nampuri, K. Narayan, Sandip Trivedi, Gauge theories with time dependent couplings and their cosmological duals, Phys. Rev. D 79, 046004 (2009), arXiv:0807.1517 [hep-th]. Atish Dabholkar, K. Narayan, Suresh Nampuri, Degeneracy of decadent dyons, J. High Energy Phys. 0803:026 (2008), arXiv:0802.0761 [hep-th]. K. Narayan, On the internal structure of dyons in N = 4 super Yang-Mills theories, Phys. Rev. D 77, 046004 (2008), arXiv:0712.3625 [hep-th]. Sumit Das, Jeremy Michelson, K. Narayan, Sandip Trivedi, Time dependent cosmologies and their duals, Phys. Rev. D 74, 026002 (2006), hep-th/0602107. David R. Morrison, K. Narayan, M. Ronen Plesser, Localized tachyons in C3/ZN, J. High Energy Phys. 0408:047 (2004), hep-th/0406039. Philip Argyres, K. Narayan, String webs from Field Theory, J. High Energy Phys. 0103:047, 2001, hep-th/0101114.

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