CURRICULUM VITAE. Degree University Year Subject Class/Remarks. Ph. D. Utkal University, 2004 String Theory Noncommutative

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1 1 CURRICULUM VITAE 1. NAME : Kamal Lochan Panigrahi 2. Address for correspondence: Department of Physics Indian Institute of Technology Kharagpur, Kharagpur , INDIA panigrahi@phy.iitkgp.ernet.in klpanigrahi@gmail.com Phone: , Fax: Personal data : Nationality : Indian Date of birth : June 16, 1975 Sex : Male Marital Status : Married 4. Education Degree University Year Subject Class/Remarks Institute of Physics/ Thesis Topic: D-branes and Ph. D. Utkal University, 2004 String Theory Noncommutative Bhubaneswar String Theory Diploma in Advanced Physics Institute of Physics 1999 Physics - Bhubaneswar Sambalpur University, M. Sc. Sambalpur 1997 Physics FIRST Utkal University, FIRST with B. Sc. Bhubaneswar 1995 Physics Distinction Council of Higher Physics 10+2 Secondary Edu, Odisha 1992 Chemistry FIRST Mathematics High Board of Mathematics School Secondary Edu, Odisha 1990 Gen. Science FIRST 5. Postdoctoral Experience INFN Fellow at Dipartimento di Fisica, Universita di Roma, Tor Vergata, ITALY ( )

2 Kamal Lochan Panigrahi 2 Postdoctoral fellow at Dipartimento di Fisica, Universita di Genova, ITALY ( ) 6. Academic positions held July 2013 onwards, Associate Professor, Department of Physics at Indian Institute of Technology Kharagpur. May 2009 to July 2013 Assistant Professor, Department of Physics & Meteorology, at Indian Institute of Technology Kharagpur. Feb to April 2009 Assistant Professor, Department of Physics at Indian Institute of Technology Guwahati. 7. Teaching Experience I have been teaching the following undergraduate and postgraduate courses: Physics- I (B.Tech 1st year (UG)), Classical Mechanics-I (UG), Classical Mechanics-II (UG), Nuclear and Particle Physics (UG), High Energy Physics (UG and PG), Quantum Field Theory (UG), Heat and Thermodynamics (UG), Quantum Mechanics-I (UG), Quantum Mechanics-II (UG), String Theory (UG and PG), Advanced Mathematical Techniques (PG). 8. Ph. D. Students supervision Dr. Pratap Kumar Swain, Topic: Semiclassical strings and D-branes in diverse string backgrounds. (Graduated in 2013) Dr. Pabitra Mohan Pradhan, Topic: Rotating and Pulsating Strings in Anti-de Sitter Space. (Graduated in 2015) Dr. Sagar Biswas, Topic: Semiclassical strings on some nonlocal string and D-brane backgrounds. (Graduated in 2015) Aritra Banerjee, Topic: Classical solutions from integrable deformations of string sigma model (about to submit Ph. D. thesis) Manoranjan Samal, Topic: Strings and D-branes in exactly solvable backgrounds. Soumya Bhattacharya, Topic: String Theory and Gravity Sorna Prava Barik, Topic: String Theory In addition I have supervised more than 15 M. Sc. projects during the past ten years.

3 Kamal Lochan Panigrahi 3 9. Ongoing Sponsored Research Title: Semiclassical strings in AdS/CFT Funding Agency: Science and Engineering Research Board (SERB) Duration: Three years Amount: Rs. 12,56, Department/Institute Responsibilities Chairman, Department Undergraduate Committee (since 2015) Department Representative: ERP (since 2014) Department Faculty in charge: Time Table ( ) Department Faculty in charge: Examinations ( ) Faculty-in-charge: Int. M. Sc. second year laboratory in Organization Convener National Strings Meeting-2013 held at Indian Institute of Technology (IIT) Kharagpur during December Organizing secretary International Conference on Theoretical and Applied Physics held at Department of Physics, IIT-Kharagpur during 1-2 December co-director of XXIV SERC school on High Energy Physics, at IIT-Guwahati in March Organizer Workshop on High Energy Physics: Particle Physics, Strings and Cosmology held at IIT-Guwahati during Feb 21-23, STC QIP: A Roadmap of Quantum Mechanics to String Theory held at IIT-Guwahati during September 03-07, Faculty advisor for B. Tech Students for two years at IIT-Guwahati. 12. Honours, Scholarships : SFB Associate Professor Fellowship to visit DESY, Hamburg in 2016 ICTP Junior Associate ( ) (awarded by The Abdus Salam International Center for Theoretical Physics, Trieste, ITALY)

4 Kamal Lochan Panigrahi 4 Visiting Scientist (May-July 2007) at Center for Quantum Spacetime (CQUeST), Sogang University, Seoul Awarded a postdoctoral fellowship by the University of Genova, ITALY in Awarded a postdoctoral fellowship in 2003 (by the Instituto Nazionale di Fisica Nucleare (I.N.F.N.)) by the Government of ITALY to do research in the University of Rome, Italy. Qualified for the GATE 98 (Graduate Aptitude test in Engineering) Qualified for the joint CSIR-UGC NET (Conducted by the Council of Scientific and Industrial Research) for eligibility of lectureship held on Senior College Merit Scholarship ( ) Junior College Merit Scholarship ( ) 13. Scientific Service: Editorial Board Member The Scientific World Journal published by Hindawi Publishing Corporation. Editorial Board Member: High Energy Physics : Dataset Papers in Physics Referee for Journal of High Energy Physics, Physics Letters B, International Journal of Modern Physics A, European Physical Journal C and Canadian Journal of Physics 14. Visits Abroad (> 1 month) Visiting Associate Professor DESY, Hamburg during May-July Visiting Scientist CERN, Switzerland May-June Visited International Centre for Theoretical Physics (ICTP) Trieste, ITALY as Junior Associate during May-July 2013 Visited ICTP, Trieste, ITALY as Junior Associate during May-July 2012 Visited CERN, Switzerland as Visiting Scientist in December Visiting Scientist at Center for Quantum Spacetime (CQUeST), Seoul, Korea during May-July Schools, Conferences and Workshops attended/to attend, Visits made

5 Kamal Lochan Panigrahi 5 1. EXTENDED WORKSHOP IN STRING THEORY held at Harish-Chandra Research Institute, Allahabad, India in November MILLENIUM MEETING IN STRING THEORY held at Jawaharlal Nehru Center, Bangalore, India in January SERC SCHOOL IN THEORETICAL HIGH ENERGY PHYSICS held at Saha Institute of Nuclear Physics, Kolkata, India in February STRINGS 2001 held at Tata Institute of Fundamental Research, Mumbai, India in January IMSC STRING WORKSHOP held at Institute of Mathematical Sciences, Chennai, India in November, SPRING SCHOOL ON SUPERSTRINGS AND RELATED MATTERS held at ICTP, Trieste, Italy in March WORKSHOP ON STRING THEORY at the Harish-Chandra Research Institute (HRI), Allahabad, December 12 21, PASCOS 2003 at Tata Institute of Fundamental Research, Mumbai, India, January 3-8, INFN MEETING at CAPRI, Italy in October INFN MEETING AT PERUGIA, Italy in December SPRING SCHOOL ON SUPERSTRINGS AND RELATED MATTERS held at ICTP, Trieste, Italy in March Strings at CERN held at CERN, Switzerland in July Visited Institute of Physics, INDIA in August SPRING SCHOOL ON SUPERSTRINGS AND RELATED MATTERS held at ICTP, Trieste, Italy in March Advanced String School held at Institute of Physics, Bhubaneswar, India in September Visiting scientist at Institute of Physics, Bhubaneswar, India May-July Participated in Strings 2009 held at University of Roma, Tor Vergata, Italy in June Visited University of Genova in June Participated in National Strings Meeting, held at Indian Institute of Technology Bombay during February 10-15, 2010.

6 Kamal Lochan Panigrahi Visiting Scientist at CERN, Geneva during December 2010 for 3 weeks. 21. Visited ICTP, Trieste as Junior Associate during May-June 2012 for 6 weeks 22. Participated in Indian Strings Meeting, held at Puri, India during December 16-21, Visited ICTP, Trieste as Junior Associate during 16 May-22 July Participated in National Strings Meeting, held at Indian Institute of Technology Kharagpur during December 22-27, Scientific Visitor at Theroy Division, CERN during 15 May-26 June STRINGS 2015 held at International Center for Theoretical Sciences, Bangalore, India in June Seminars and Talks 1. Delivered a seminar on D-brane Bound States from Charged Mcroscopic Strings in the IMSC STRING WORKSHOP held at Institute of Mathematical Sciences, Chennai, India in November, Delivered a seminar on D-branes and Noncommutative String Theory at Institute of Physics, Bhubaneswar, in February, Delivered a seminar on Bound States of String Networks and D-branes at University of Roma, Tor Vergata, Italy in March, Delivered a seminar on p-p branes in PP-wave Background in Workshop in string theory at Harish-Chandra Research Institute (HRI), Allahabad, in December, Delivered a seminar on Intersecting p-p branes in PP-wave Background in PAS- COS 2003 at Tata Institute of Fundamental Reseacrh, Mumbai, INDIA in January, Delivered a seminar on H-deformed branes and Horizons in plane wave Spacetime at University of Perugia, Italy, in December Delivered a seminar on H-deformed branes and Horizons in plane waves at University of Rome, Tor Vergata, Rome, Italy in February Delivered a seminar on Rolling branes in Dp-brane background, at University of Rome, Tor Vergata, Rome, Italy in October Delivered a seminar on Rolling Brane Dynamics Near NS5-branes at Dipartimento di Fisica, Universita di Genova in February 2005.

7 Kamal Lochan Panigrahi Delivered seminar on D-brane dynamics in curved backgrounds at Harish-Chandra Research Institute (HRI), Allahabad, INDIA at Indian Institute of Technology (IIT), Kanpur, INDIA at Indian Association for Cultivation of Science (IACS), Kolkata, INDIA and at Institute of Physics, Bhubaneswar, INDIA in August Delivered a seminar on D-branes in cosmological backgrounds at Institute of Physics, India in March Delivered a seminar on D-brane dynamics at Institute of Mathematical Sciences, Chennai, India in March Delivered a seminar on Geometric tachyon dynamics, and D-branes in a big bang/big crunch universe at Center of High Energy Physics (CHEP), Indian Institute of Science, Bangalore, India in July Delivered a seminar on D-branes static and dynamics in curved backgrounds at Indian Institute of Technology, Guwahati, India in September Invited seminar on Lagrangian formulation of Higher spin theories on AdS space at the international conference (Indian String Meeting (ISM06)) at Puri, India in December Delivered a seminar on D-branes in a Null Linear Dilaton Background at Physics Academy of North East (PANE 07), Gauhati University, India in March Delivered a Seminar on Massless Higher spin theories on AdS at Center for Quantum Spacetime, Sogang University, Seoul in June Delivered a seminar on On the geometrical tachyon and universal open string tachyon, at Institute of Physics, India in October Delivered a seminar on The geometrical tachyon and universal open string tachyon, at Saha Institute of Nuclear Physics, in December Delivered a seminar on String theory: Is this a theory of everything?, at Indian Institute of Science Education and Research (IISER) Kolkata, in February Delivered a seminar on Massless Higher Spin theories in AdS space, at S. N. Bose Centre for Basic Sciences, Kolkata in February Delivered a seminar on Spiky strings and Wilson loops in AdS(4) x CP**3 at the Department of Physics, University of Genova in June Delivered a seminar on AdS/CFT and Semiclassical Strings, at Indian Institute of Science Education and Research (IISER) Thiruvananthapuram, in July 2010.

8 Kamal Lochan Panigrahi Delivered a seminar on Rotating Strings in AdS at the Scuola Normale Superiore, PISA in June Delivered a seminar on String Theory and AdS/CFT duality at the Sambalpur University, India in February Delivered a seminar on Semiclassical strings in AdS and AdS/CFT duality at the Centre for High Energy Physics, Indian Institute of Sciences, Bangalore in July Delivered a seminar on Semiclassical strings on AdS x S and its deformations at Banaras Hindu University in November Delivered a seminar on Strings in integrable deformations of AdS5 x S5 at Saha Institute of Nuclear Physics, Kolkata in February Delivered a seminar on String side story of AdS/CFT duality at NISER in February Delivered a seminar on On the string side of AdS/CFT and their deformations in the Department of Physics at IIT-Kharagpur in March 2016.

9 Kamal Lochan Panigrahi List of Referees 1. Professor Augusto Sagnotti Scuola Normale Superiore Piazza dei Cavalieri, Pisa ITALY a.sagnotti@sns.it fax: Professor Ignatios Antoniadis Department of Physics, CERN Theory Division, CH-1211, Geneva 23, Switzerland Ignatios.Antoniadis@cern.ch ignatios.antoniadis@polytechnique.edu fax: Professor Carlo M. Becchi Dipartimento di Fisica Universita di Genova Via Dodecaneso Genova, ITALY carlomaria.becchi@ge.infn.it fax:

10 Kamal Lochan Panigrahi 10 List of Publications 1. A. Banerjee and Kamal L. Panigrahi, On circular strings in (AdS 3 S 3 ) κ, arxiv: [hep-th]. 2. Kamal L. Panigrahi and M. Samal, Chaos in classical string dynamics in ˆγ deformed AdS 5 T 1,1, arxiv: [hep-th]. 3. A. Banerjee, K. L. Panigrahi and M. Samal, A note on oscillating strings in AdS 3 S 3 with mixed three-form fluxes, JHEP 1511, 133 (2015) arxiv: [hepth]. 4. A. Banerjee, S. Bhattacharya, and Kamal L. Panigrahi, Spiky strings in κ-deformed AdS, JHEP 1506, 057 (2015), arxiv: [hep-th] 5. S. Biswas and Kamal L. Panigrahi, Rotating and Orbiting Strings in Dp-brane background, JHEP (2015) arxiv: [hep-th]. 6. Kamal L. Panigrahi, P. M. Pradhan and M. Samal, Pulsating strings on (AdS 3 S 3 ) κ, JHEP (2015) arxiv: [hep-th]. 7. A. Banerjee and Kamal L. Panigrahi, On the Rotating and Oscillating strings in (AdS 3 S 3 ) κ, JHEP (2014), [arxiv: ]. 8. A. Banerjee, Kamal L. Panigrahi and P. M. Pradhan, Spiky strings on AdS 3 S 3 with NS-NS flux, Phys. Rev. D 90, 10, (2014), [arxiv: [hep-th]]. 9. A. Banerjee, S. Biswas and Kamal L. Panigrahi, Semiclassical Strings in Supergravity PFT, Eur. Phys. J. C74 (2014) 10, 3115, arxiv: [hep-th]. 10. S. Biswas and Kamal L. Panigrahi, Semiclassical Strings on Curved Branes, JHEP 1310, 106 (2013), arxiv: [hep-th]. 11. P. M. Pradhan and Kamal L. Panigrahi, Pulsating Strings With Angular Momenta,, Phys. Rev. D 88, (2013), arxiv: [hep-th]. 12. T. K. Dey and Kamal L. Panigrahi, Mass Deformed L-BLG Theory From ABJ Theory, Phys. Rev. D 86, (2012), arxiv: [hep-th] 13. Kamal L. Panigrahi and P. K. Swain, On the D-brane solutions in Godel Universe, arxiv: [hep-th]. 14. Kamal L. Panigrahi and P. M. Pradhan, On Rotating and Oscillating Four-Spin Strings in AdS 5 S 5, JHEP 1211, 053 (2012), arxiv: [hep-th]. 15. S. Biswas and Kamal L. Panigrahi, Spiky Strings on I-brane,JHEP 1208, 044 (2012), arxiv: [hep-th].

11 Kamal Lochan Panigrahi Kamal L. Panigrahi, P. M. Pradhan and P. K. Swain, Three Spin Spiky Strings in β-deformed Background, JHEP (2012), arxiv: [hep-th]. 17. Kamal L. Panigrahi, P. M. Pradhan, P. K. Swain. Rotating Strings in AdS 4 CP 3 with B-NS holonomy, JHEP , 2012, arxiv: [hep-th]. 18. P. S. Kwon, G. Y. Jun, Kamal L. Panigrahi, M. Sami, Inflation driven by single geometric tachyon with D-brane orbiting around NS5-branes, Phys. Lett. B712 10, (2012) arxiv: [hep-th]. 19. S. Biswas, Kamal L. Panigrahi, Spiky Strings on NS5-branes, Phys. Lett. B , (2011), arxiv: [hep-th]. 20. J. Kluson and Kamal L. Panigrahi, T-Duality For String in Horava-Lifshitz Gravity, Eur. Phys. J. C 71, 1595, (2011), arxiv: [hep-th]. 21. Kamal L. Panigrahi and S. Roy, Drag force in a hot non-relativistic, non-commutative Yang-Mills plasma, JHEP , 2010, arxiv: [hep-th]. 22. J. Kluson and Kamal L. Panigrahi, Wilson Loops from D-branes in AdS 4 CP 3 with B NS holonomy,, Eur. Phys. J. C67 565, 2010, arxiv: [hep-th]. 23. B. Gwak, B. H. Lee, Kamal L. Panigrahi and C. Park, Semiclassical strings in AdS 3 S 2, JHEP , 2009, arxiv: [hep-th] 24. S. Jain and Kamal L. Panigrahi, Spiky Strings in AdS 4 CP 3 with Neveu-Schwarz Flux, JHEP , arxiv: [hep-th]. 25. J. Kluson and Kamal L. Panigrahi, Defects and Wilson Loops in 3d QFT from D-branes in AdS 4 CP 3, Euro. Phys. J. C 61, 339, 2009, arxiv: [hep-th] 26. B. H. Lee, Kamal L. Panigrahi, C. Park, Spiky strings on AdS 4 CP 3,JHEP , 2008, arxiv: [hep-th]. 27. J. Kluson, B. H. Lee, Kamal L. Panigrahi, C. Park, Magnon like solutions for strings in I-brane background, JHEP 0808, 032 (2008), arxiv: [hep-th]. 28. B. H. Lee, R. R. Nayak, Kamal L. Panigrahi, C. Park, On the giant magnon and spike solutions for strings on AdS 3 S 3, JHEP (2008) arxiv: [hep-th]. 29. Kamal L. Panigrahi, and H. Singh, Spinflation from Geometric Tachyon, JHEP 0805: 088 (2008), arxiv: [hep-th]. 30. J. Kluson, and Kamal L. Panigrahi, D1-brane in beta-deformed Background, JHEP 0711: 011 (2007), arxiv: [hep-th] 31. Kamal L. Panigrahi, and H. Singh, Assisted Inflation from Geometric Tachyon, JHEP 0711: 017 (2007) arxiv: [hep-th].

12 Kamal Lochan Panigrahi J. Kluson, and Kamal L. Panigrahi, On the Universal Tachyon and Geometrical Tachyon, JHEP 0706 :015, 2007 arxiv: [hep-th]. 33. J. Kluson, R. R. Nayak, and Kamal L. Panigrahi, Giant Magnon in NS5-brane background, JHEP 0704: 099,2007 hep-th/ N. Ohta and Kamal L. Panigrahi, Supersymmetric Intersecting Branes in Timedependent Backgrounds, Phys. Rev. D74, (2006) hep-th/ A. Fotopoulos, Kamal L. Panigrahi, M. Tsulaia, Lagrangian formulation of Higher Spin Theories on AdS Space, Phys. Rev. D 74, (2006) hepth/ R. R. Nayak, Kamal L. Panigrahi, and S. Siwach, Time-dependent supergravity solutions in null dilaton background, Phys. Lett. B (2006),arXiv:hepth/ R. R. Nayak, and Kamal L. Panigrahi, D-brane solutions in a light-like linear dilaton background, Phys. Lett. B (2006), arxiv:hep-th/ J. Kluson, R. R. Nayak, and Kamal L. Panigrahi, D1-brane with Overcritical Electric Field in AdS3 and S-brane, JHEP 05 (2006) 022, arxiv: hep-th/ J. Kluson, R. R. Nayak, and Kamal L. Panigrahi, D-brane dynamics in a plane wave background, Phys. Rev. D 73, (2006), arxiv: hep-th/ J. Kluson, and Kamal L. Panigrahi, Anti-de Sitter D-brane Dynamics, JHEP 0511 (2005) 045, arxiv: hep-th/ Y. Hikida, R. R. Nayak, and Kamal L. Panigrahi, D-branes in a Big Bang/Big Crunch Universe: Misner Space, JHEP 0509 (2005) 023, arxiv: hep-th/ J. Kluson, and Kamal L. Panigrahi, Supertube Dynamics in Diverse Backgrounds, JHEP0508 (2005) 033, arxiv: hep-th/ Y. Hikida, R. R. Nayak, and Kamal L. Panigrahi, D-branes in a Big Bang/Big Crunch Universe: Nappi-Witten Gauged WZW Model, JHEP 0505 (2005) 018, arxiv: hep-th/ Y. Nakayama, Kamal L. Panigrahi, S.-J. Rey, and H. Takayanagi, Rolling Down the Throat in NS5-brane Background: The Case of Electrified D-Brane, JHEP 0501 (2005) 052, arxiv:hep-th/ Kamal L. Panigrahi, D-Brane Dynamics in Dp-Brane Background, Phys. Lett. B (2004), arxiv:hep-th/ R. R. Nayak, Kamal L. Panigrahi, and S. Siwach, Brane Solutions with/without Rotation in PP-wave Spacetime, Nucl. Phys. B (2004), arxiv:hep-th/

13 Kamal Lochan Panigrahi S. F. Hassan, R. R. Nayak, and Kamal L. Panigrahi, D-branes in the NS5 Nearhorizon pp-wave Background, arxiv:hep-th/ R. R. Nayak, and Kamal L. Panigrahi, More D-branes in plane wave spacetime, Phys. Lett. B (2003), arxiv:hep-th/ N. Ohta, Kamal L. Panigrahi, and S. Siwach, Intersecting branes in pp-wave spacetime, Nucl. Phys. B (2003), arxiv:hep-th/ Kamal L. Panigrahi, and S. Siwach, D-branes in pp-wave spacetime with nonconstant NS-NS flux, Phys. Lett. B (2003), arxiv:hep-th/ A. Biswas, A. Kumar and Kamal L. Panigrahi, p-p Branes in PP-wave Background, Phys. Rev. D (2002), arxiv:hep-th/ A. Biswas, and Kamal L. Panigrahi, Intersecting Membranes from Charged Macroscopic Strings, Mod. Phys. Lett. A (2002), arxiv:hep-th/ A. Kumar, S. Mukherji, and Kamal L. Panigrahi, D-brane Bound States from Charged Macroscopic Strings, JHEP (2002), arxiv: hep-th/ A. Kumar, R. R. Nayak, and Kamal L. Panigrahi, Bound States of String Networks and D-branes, Phys. Rev. Lett (2002), arxiv: hep-th/ A. Kumar, A. Misra, and Kamal L. Panigrahi, Noncommutative N=2 Strings, JHEP (2001), arxiv:hep-th/ Conference Proceeding 56. A. Biswas, A. Kumar, and K.L. Panigrahi, INTERSECTING P-P-PRIME BRANES IN PP-WAVE BACKGROUND, Prepared for 9th International Symposium on Particles, Strings and Cosmology (PASCOS 03), Mumbai (Bombay) India, 3-8 Jan Published in Pramana (2004).

14 Kamal Lochan Panigrahi 14 Research Summary and Plan String theory, D-branes and AdS/CFT duality: In the last few years my research focus of attention has been the study of AdS/CFT correspondence, D-branes and string theory in various time-dependent exact string backgrounds by using the methods of conformal field theory and the effective field theory. I am also interested in topics of Higher Spin gauge theory. Semiclassical Strings in AdS and its integrable deformations: The AdS/CFT correspondence is a remarkable equivalence between two very different types of theories, Gauge theory String theory. Both types of theories play central role in modern theoretical high-energy physics. Gauge theories are the basis of the standard model of particle physics while string theory is the leading candidate for a quantum theory of gravity. The best understood case of the AdS/CFT correspondence is the equivalence between N = 4 SUSY Yang-Mills theory and type IIB string on AdS 5 S 5. The gauge theory is non- Abelian gauge theory defined in dimensions like those describing the strong and electro-weak interactions in the standard model. AdS/CFT is a weak-strong coupling duality meaning that the gauge and string sides of the correspondence are tractable in different regimes, which means that proving this duality is extremely hard. Fortunately in recent years the integrability of both sides of duality has been extremely useful for establishing the correspondence more, by showing that the theories on both sides of correspondence are solvable in certain limits. In this connection, Hofman and Maldacena (HM) proposed a special limit where the problem of determining the spectrum of both sides becomes rather simple. The spectrum consists of an elementary excitation known as magnon which propagate with a conserved momentum p along the long spin chain. In the dual formulation, the most important ingredient is semiclassical string solutions, which can be mapped to long trace operator with large energy and large angular momenta. Our focus has been to compute various rigidly rotating strings in AdS and AdS-like backgrounds to find out spiky string configurations and check what we learn from the dual formulation. We found a large class of these solutions in AdS 3 S 3 background, with spin angular momentum along some directions inside AdS 3. We have further found out similar solutions in the near horizon geometry of stack of large NS5-branes. Furthermore, we have obtained spiky strings and magnon solutions in the AdS 4 CP 3 background with and without background flux. The generic feature of all these solutions is that they satisfy a particular dispersion relation among various conserved charges. In the dual formulation they correspond to long trace operators of the dual gauge theory living of the boundary. We have been investigating the role of semiclassical strings (both rotating and pulsating strings) in understanding the conjectured duality better. This provides further support into the AdS/CFT correspondence. More recently, integrable deformations of AdS have been investigated in detail and further insight in trying to get more general theories have been obtained by using the map. Even though the dual gauge theory is not understood completely, but the hope that with the studies of strings in the bulk, one may be able to look for suitable theories. In this connection we have been able to study some rotating and pulsating strings and derived new results which are very interesting. More recently

15 Kamal Lochan Panigrahi 15 we are trying to understand the gauge theory dual in detail. D-brane dynamics, Geometric Tachyon, and Inflationary Scenario: In string theory, D-branes have emerged as important objects in understanding the nonperturbative dynamics of string theory and gauge theories. They have been useful in understanding the string and gauge theory correspondence known as AdS/CFT correspondence. They have also played an important role in establishing various strong-weak dualities in string theory. In the study of tachyon dynamics, in open string theories, construction of various time dependent classical solutions has been an important area of research in the recent past. These solutions represent the decay of an unstable D-brane or a brane-antibrane pair as the tachyon rolls towards the minimum of the potential. Indeed, if we replace the tachyon a bit from its maximum of its potential, it rolls towards the minimum and the final decay product has the equation of state of that of a non-interacting and pressureless dust (known as tachyon matter) and there are no perturbative excitations around the minimum of its potential. This gives a qualitative picture of the open-closed duality, namely if one starts with a system with open strings, in the end one is left with only closed string radiations. These solutions, in general, are constructed by perturbing the boundary conformal eld theory that describes the D-brane by an exact marginal deformation. More recently the open string tachyon has got a geometric interpretation, in the form of a rolling branes in the NS5-background. The radial mode on the probe D-brane has been identified with the geometrical tachyon, and the relevant physics got interesting meaning. The classical Dirac-Born-Infeld analysis has also been lifted to the full string theory level by analyzing the branes in N = 2 Liouville theory. In this direction, I have studied a related problem on the dynamics of rolling branes in the generic Dp-brane background. Unlike the case of the rolling tachyon, the potential in this problem have a power-like behavior. But nevertheless by analyzing carefully, one is able to show that at very late times, this system has the same behavior as that of the rolling tachyon problem. The homogeneous decay of the p-brane in a D(p + 2) background admits a final state which resembles with that of the pressureless dust at very late times. Hence the speculation is that the generic properties of the open-string tachyon could be analyzed in a more complicated set up. In another development, we have studied rolling radion dynamics of electrified D-brane in NS5-brane background, both in effective field theory and in full open string theory, by constructing the relevant boundary states. We construct exact boundary states and, from them, extract conserved Noether currents. By applying Lorentz covariance, we show how the decay of electrified D-brane is related to that of bare D-brane. We compute spectral moments of final state energy and winding quantum number. Using Lorentz covariance argument, we explain in elementary way why winding quantum number should be included and derive rules how to do so. We conclude that the geometric realization between radion rolling dynamics and tachyon rolling dynamics holds universally, both for bare and electrified D-branes. We have further studied the time dependent dynamics of the D-branes in curved back- grounds, in the hamiltonian formulation. First we study the supertube- a bunch of straight string with the D0-brane blown up into the spherical D2- brane by the Born-Infeld electric and magnetic fields dynamics in diverse backgrounds. We have furthermore studied the anti-de Sitter D-brane

16 Kamal Lochan Panigrahi 16 dynamics in Hamiltonian formulation. By exploiting the existence of certain conserved charges, we have solved the equation of motion for a D1-brane in the AdS 3 background and find the space-time dependent solutions. We further studied the dynamics by mapping the problem to that of the open string tachyon, and examine the time dependent solutions in some detail. More recently the relationship between the geometric tachyon and the universal open string tachyon has also been analyzed. We have studied various properties of non-bps D(p + 1)-brane in the background of k NS5-branes, with one of the transverse direction compactified on a circle, from the point of view of Dirac-Born-Infeld action. We have analysed two different embedding of non-bps D(p + 1)-brane in given background and study the classical solutions of the world-volume theory. We have argued for the configuration of a non-bps D(p + 1)-brane which allows us to find solutions of the equations of motion that give unified descriptions of G (D-branes with geometric instability) and U-type (branes with the usual open string tachyon in its world volume) branes. In the last few years string inspired cosmology has been one of the very important field of research to derive quantities of inflationary universe. In particular the tachyon cosmology has been very successful barring some issues in reheating phenomena. The tachyon in the open string theories has been interpreted as an inflaton field and one derives various quantities pertaining to slow roll inflation. We once again take the D-branes in curved space time geometry and study assisted inflation. We have studied the effect of rolling of N D3-branes in the vicinity of NS5-branes. We find out that this system coupled with the four dimensional gravity gives the slow roll assisted inflation of the scalar field theory. Once again this expectation is exactly similar to that of N-tachyon assisted inflation on unstable D-branes. String theory in time dependent background One of the interesting problems pertaining to space like singularities is that whether the space-like singularities at the early universe cosmology can be resolved by the string theoretic techniques. Near the Big-Bang/Big-Crunch singularies the usual laws of physics breaks down, and it has not been possible to predict the theory from the point of view of general theory of relativity. Recently a flat background with a linear dilaton has been proposed to be an exact and supersymmetric solution of string theory which can be taken as a model for big bang/big crunch singularity. The dual Matrix theory description has been given in terms of a (1+1)-d supersymmetric Yang-Mills theory on a time-dependent world-sheet given by the Milne orbifold of (1+1)-d Minkowski space. We have studied a non-trivial extension of this background by including various fuxes. We have been able to find out that at early times the theory is strongly coupled, and it can be described by means of a matrix string theory and at late times it can be treated as a free theory. We further have constructed some time dependent supergravity solution and recently are trying to understand the possible gauge duals. The formulation of string theory in cosmological (or broadly time-dependent backgrounds) has been one of the most exciting and challenging subject. Among other things, it is important to see how the string theory resolves the initial space-like singularities of the early universe. We have investigated the D-branes in a two-dimensional Lorentzian orbifold R 1,1 /Γ with a discrete boost Γ. This space is known as Misner or Milne space, and includes big crunch/big bang singularity. In this space, there are D0-branes in spiral orbits and D1- branes with or without flux on them.

17 Kamal Lochan Panigrahi 17 In particular, we observe imaginary parts of partition functions, and interpret them as the rates of open string pair creation for D0-branes and emission of winding closed strings for D1-branes. These phenomena occur due to the time-dependence of the background. Open string 2 2 scattering amplitude on a D1- brane is also computed and found to be less singular than closed string case. We have further investigated the Nappi-Witten model as a conformal field theory model which includes big bang/big crunch singularities. This model can be described a (SL(2; R) SU(2))/(U(1) U(1)) Wess-Zumino-Witten model, that describes a four dimensional anisotropic universe starting at a big bang singularity, expanding for a while and end at a big crunch singularity. It has also regions that contain closed-time-like curves (CTCs). We have investigated, with probe D-branes, the singularities and the CTCs. We classified all the branes in a group theoretic way and then verified their existence in the effective field theory approach. We have been able to show that the D-brane metric from the DBI action does not contain singularities and the wave functions on them are well behaved even in the presence of closed time like curves. Higher Spin Gauge Theory: Massless Higher Spin gauge theories are classical field theories which describe self-interacting massless fields with an arbitrary spin. Being an interesting subject by itself Higher Spin gauge theories recently triggered an increasing interest because of their possible connection with the String and M-theory, namely it has been conjectured that massless Higher Spin theory is the most symmetrical phase of String theory the later being spontaneously broken phase of the former. We have given an alternative formulation to reducible higher spin fields on AdS which, though describes the same physical polarizations, is new in a sense that it is carried out in a (D+1)-dimensional ambient space of a D-dimensional AdS. We have formulated the Lagrangian description of reducible Higher Spin fields in the framework of BRST approach. We believe that this formulation might be useful for further studies of interacting higher spin theories on AdS background.