Hello and Welcome to my home page !!

My name is Kamal Lochan Panigrahi. I work in the research areas of String theory and D-branes, String Cosmology and Higher Spin gauge theory.

My Research Interest: I am interested in all aspects of string theory, with special interest in

1. D-brane dynamics

2. AdS/CFT correspondence

3. Inflation is string theory

4. Higher Spin Gauge theory

5. Open string Tachyons

The papers that I wrote in these fields include:

Research Publications

1. B. -H. Lee, Kamal L. Panigrahi, C. Park, Spiky Strings on AdS(4) x CP**3, arXiv:0807.2559 [hep-th].

2. J. Kluson, B. -H. Lee, Kamal L. Panigrahi, C. Park, Magnon like solutions for strings in I-brane background, arXiv:0806.3879 [hep-th] (accepted in JHEP).

3. B. -H. Lee, R. R. Nayak , Kamal L. Panigrahi, C. Park, On the giant magnon and spike solutions for strings on AdS(3) x S**3, JHEP 0806: 065, 2008, arXiv:0804.2923 [hep-th].

4. Kamal L. Panigrahi, H. Singh, Spinflation from Geometric Tachyon, JHEP 0805:088, 2008, arXiv:0802.4230 [hep-th]

5. J. Kluson, and Kamal L. Panigrahi, D1-brane in beta deformed background, JHEP 0711:011, 2007, arXiv:0710.0148 [hep-th]

6. Kamal L. Panigrahi, H. Singh, Assisted Inflation from Geometric Tachyon, JHEP 0711:017, 2007, arXiv:0708.1679[hep-th]

7. J. Kluson, and Kamal L. Panigrahi, On the Universal Tachyon and Geometrical Tachyon, JHEP 0706: 015, 2007, arXiv:0704.3013 [hep-th]

8. J. Kluson, R. R. Nayak and Kamal L. Panigrahi, Giant Magnon in NS5-brane background, JHEP 0704:099,2007, hep-th/0703244

9. N. Ohta and Kamal L. Panigrahi, Supersymmetric Intersecting Branes in Time-dependent Backgrounds, Phys.Rev.D74:126003,2006, arXiv: hep- th/0610015

10. A. Fotopoulos, Kamal L. Panigrahi, M. Tsulaia, Lagrangian formulation of Higher Spin Theories on AdS Space, Phys. Rev. D 74, 085029 (2006), arXiv: hep-th/0607248.

11. R. R. Nayak, Kamal L. Panigrahi, and S. Siwach, Time-dependent supergravity solutions in null dilaton background, Phys. Lett. B640 214 (2006),arXiv:hep-th/0605278.

12. R. R. Nayak, and Kamal L. Panigrahi, D-brane solutions in a light-like linear dilaton background, Phys. Lett. B638 362 (2006), arXiv:hep-th/0604172.

13. J. Kluson, R. R. Nayak, and Kamal L. Panigrahi, D1-brane with Overcritical Electric Field in AdS3 and S-brane, Journal of High Energy Physcis (JHEP) 05 (2006) 022, arXiv: hep-th/0602211.

14. J. Kluson, R. R. Nayak, and Kamal L. Panigrahi, D-brane dynamics in a plane wave background, Phys. Rev. D 73, 066007 (2006), arXiv: hep-th/0512159.

15. Kluson, and Kamal L. Panigrahi, Anti-de Sitter D-brane Dynamics, JHEP 0511 (2005) 045, arXiv: hep-th/0509065.

16. 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/0508003.

17. Kluson, and Kamal L. Panigrahi, Supertube Dynamics in Diverse Backgrounds, JHEP 0508 (2005) 033, arXiv: hep-th/0506012.

18. 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/0503148.

19. 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/0412038.

20. Kamal L. Panigrahi, D-Brane Dynamics in Dp-Brane Background, Phys. Lett. B601, 64 (2004), arXiv:hep-th/0407134.

21. R. R. Nayak, Kamal L. Panigrahi, and S. Siwach, Brane Solutions with/without Rotation in PP-wave Spacetime, Nucl. Phys. B698, 149 (2004), arXiv:hep-th/0405124.

22. S. F. Hassan, R. R. Nayak, and Kamal L. Panigrahi, D-branes in the NS5 Near-horizon pp-Wave Background, arXiv:hep-th/0312224.

23. Nayak, and Kamal L. Panigrahi, More D-branes in plane wave spacetime, Phys. Lett. B575, 325 (2003), arXiv:hep-th/0310219.

24. N. Ohta, Kamal L. Panigrahi, and S. Siwach, Intersecting branes in pp-wave spacetime, Nucl. Phys. B674, 306 (2003), arXiv:hep-th/0306186.

25. Kamal L. Panigrahi, and S. Siwach, D-branes in pp-wave spacetime with nonconstant NS-NS flux, Phys. Lett. B561, 284 (2003), arXiv:hep-th/0303182.

26. A. Biswas, A. Kumar and Kamal L. Panigrahi, p-p' Branes in PP-wave Background, Phys. Rev. D66, 126002 (2002), arXiv:hep-th/0208042.

27. A. Biswas, and Kamal L. Panigrahi, Intersecting Membranes from Charged Macroscopic Strings, Mod. Phys. Lett. A17, 1297 (2002), arXiv:hep- th/0205138.

28. A. Kumar, S. Mukherji, and Kamal L. Panigrahi, D-brane Bound States from Charged Macroscopic Strings, JHEP 0205, 050 (2002), arXiv: hep-th/0112219.

29. A. Kumar, R. R. Nayak, and Kamal L. Panigrahi, Bound States of String Networks and D-branes, Phys. Rev. Lett. 88, 121601 (2002), arxiv: hep- th/0108174.

30. A. Kumar, A. Misra, and Kamal L. Panigrahi, Noncommutative N=2 Strings, JHEP 0102, 037 (2001), arXiv:hep-th/0011206.

31. A. . Biswas, A. Kumar, and Kamal L. Panigrahi, INTERSECTING P-P-PRIME BRANES IN PP-WAVE BACKGROUND, Prepared for 9^th International Symposium on Particles, Strings and Cosmology (PASCOS 03), Mumbai (Bombay) India, 3-8 Jan 2003, Pramana 62, 703 (2004).

My Research:

I am interested in research areas of various aspects of string theory and D-branes. In the last few years my focus on research has been to understand various aspects of string theory and D-branes in time dependent backgrounds from the view point of conformal field theory and from the effective field theory prospective, Time dependent tachyon condensation and S-branes and aspects of Higher Spin Gauge Theory. More recently I am interested in string cosmology.

Rigid rotating strings in Anti-de Sitter backgrounds: I am interested in various aspects of rigid rotating strings in various backgrounds. We study solutions for the rotating strings on the sphere and on the Anti-de-Sitter spacetime. We find the giant magnon and single spike solutions in the presence of constant magnetic field. We further study the rotating string on AdS(3) x S**3 geometry with two conserved angular momenta on S**3 and a spin along the AdS(3). We find the solutions corresponding to a circular string and a helical string. We further study giant magnon and spike solutions for the string rotating on
AdS(4) X CP**3 geometry. We consider rigid rotating fundamental string in the SU(2) X SU(2) sector inside the CP**3 and find out the general form of all the conserved charges. We find out the dispersion relation corresponding to both the known giant magnon and the new spike solutions. We further study the finite size correction in both cases.

String theory in time-dependent Background: I am interested in various aspects of strings and branes in time dependent (or cosmological) backgrounds. A flat background with a linear dilaton is 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 fluxes. 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.

We have investigated D-branes in a two-dimensional Lorentzian orbifold. 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. In particular, we observe imaginary parts of partition functions, and interpret the 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 à 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) \times SU(2))/(U(1) \times 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.

D-brane Dynamics in diverse backgrounds

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. 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. We argue that T-duality and Lorentz boost offer an intuitive approach. In the limit of large number of NS5-branes, both boundary wave functions and conserved currents are sharply peaked and agree with those deduced from the effective field theory. As the number of NS5-branes is reduced, width around the peak becomes wider by string corrections. We also study radiative decay process. 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.

Higher Spin Gauge Theory

I am interested in various aspects of Higher spin gauge theory and its relation to string theory. I have been working on the Higher Spin gauge theory on Anti de-Sitter space in a Lagrangian formulation. 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 Higher Spin Fields on AdS background.

Inflation in string theory

We study 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. We further study the assisted inflation scenario from the rolling of N BPS D3-brane into the NS5-branes, on a transverse geometry of R**3 x S**1, coupled to four dimensional gravity. We assume that the branes are distributed along the circle S**1 and the probe D3-branes spin along R**3 plane. Qualitatively this process is similar to that of N-tachyon assisted inflation on unstable D-branes. We further study the spinflation scenario numerically and analyze its effect.

Collaborators:

C.M. Becchi, M. Bianchi , C. Imbimbo, A. Sagnotti (Italy), S. J. Rey, B. H. Lee, C. Park (S. Korea), Y. Hikida, Y. Nakayama, N. Ohta, H. Takayanagi (Japan), S. F. Hassan (Sweden), J. Kluson (Czech Republic), M. Tsulaia and A. Fotopoulos (Greece), A. Biswas, A. Kumar, A. Misra, S. Mukherji, H. Singh, S. Siwach (India)

My Education

Ph. D. in Physics: Thesis Submitted in August 2003, Degree awarded in August 2004 (Institute of Physics, India)

Topic: D-branes and Noncommutative string theory

Postdoctoral Experience:

1. INFN Fellow at Dipartimento di Fisica, Universita di Roma, ``Tor Vergata'', ITALY (2003 - 2005)

2. Postdoctoral fellow at Dipartimento di Fisica (DIFI), Universita’ di Genova, ITALY (2005 - 2006)

Teaching:

July-Nov (2006) : Nuclear and Particle Physics (MSc)

January-May (2007) : High Energy Physics (MSc Elective)

July-Nov (2007) : Nuclear and Particle Physics (MSc)

January-May (2008): Quantum Field Theory (MSc Elective)

July-Nov (2008): Quantum Mechanics I (MSc)

Honours, Scholarships

· ICTP Junior Research Associate (2007-2012) awarded by The Abdus Salam International Center for Theoretical Physics

· Visiting Scientist (May-July 2007) at Center for Quantum Spacetime (CQUeST), Seoul

· Awarded a postdoctoral fellowship by the University of Genova, ITALY in 2005.

· 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 (Graduate Aptitude Test in Engineering)

· Qualified for the joint CSIR-UGC NET (Conducted by the Council of Scientific and Industrial Research)

· Senior College Merit Scholarship (1992-1995)

· Junior College Merit Scholarship (1990-1992)

Scientific Service

Referee for JHEP (Journal of High Energy Physics)

Referee for Physics Letters B

Schools, Conferences and Workshops attended/to attend

· ``EXTENDED WORKSHOP IN STRING THEORY" held at Harish-Chandra Research Institute, Allahabad, India in November 1999.

· ``MILLENIUM MEETING IN STRING THEORY" held at Jawaharlal Nehru Center, Bangalore, India in January 2000.

· ``SERC SCHOOL IN THEORETICAL HIGH ENERGY PHYSICS" held at Saha Institute of Nuclear Physics, Kolkata, India in February 2000.

· ``STRINGS 2001" held at Tata Institute of Fundamental Research, Mumbai, India in January 2001.

· ``IMSC STRING WORKSHOP" held at Institute of Mathematical Sciences, Chennai, India in November, 2001.

· `` SPRING SCHOOL ON SUPERSTRINGS AND RELATED MATTERS'' held at ICTP, Trieste, Italy in March 2002.

· `` WORKSHOP ON STRING THEORY'' at the Harish-Chandra Research Institute (HRI), Allahabad, December 12 -- 21, 2002.

· ``PASCOS 2003'' at Tata Institute of Fundamental Research, Mumbai, India, January 3-8, 2003.

· ``INFN MEETING'' at CAPRI, Italy in October 2003.

· ``INFN MEETING'' AT PERUGIA, Italy in December 2003.

· ``SPRING SCHOOL ON SUPERSTRINGS AND RELATED MATTERS'' held at ICTP, Trieste, Italy in March 2004.

· ''Strings at CERN'' held at CERN, Switzerland in July 2004.

· Visited Institute of Physics, INDIA in August 2004.

· ``SPRING SCHOOL ON SUPERSTRINGS AND RELATED MATTERS'' held at ICTP, Trieste, Italy in March 2005.

· Advanced String School held at Institute of Physics, Bhubaneswar, India in September 2006.

· Indian String Meeting (ISM06) held at Toshali Sands, Puri, India in December 2006.

· Visiting Scientist at Institute of Physics, Bhubaneswar, India May-June 2008

Seminars and Talks delivered

· Delivered a seminar on ``D-brane Bound States from Charged Macroscopic Strings'' in the ``IMSC STRING WORKSHOP'' held at Institute of Mathematical Sciences, Chennai, India in November, 2001.

· Delivered a seminar on ``D-branes and Noncommutative String Theory'' at ``Institute of Physics, Bhubaneswar'', in February, 2002.

· Delivered a seminar on ``Bound States of String Networks and D-branes" at ``University of Roma, Tor Vergata", Italy in March, 2002.

· 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, 2002

· Delivered a seminar on ``Intersecting p-p' branes in PP-wave Background'' in ``PASCOS 2003'' at ``Tata Institute of Fundamental Reseacrh, Mumbai, INDIA in January, 2003.

· Delivered a seminar on ``H-deformed branes and Horizons in plane wave Spacetime'' at ``University of Perugia, Italy, in December 2003.

· Delivered a seminar on ``H-deformed branes and Horizons in plane waves'' at ``University of Rome, Tor Vergata'', Rome, Italy in February 2004.

· Delivered a seminar on ``Rolling branes in Dp-brane background'', at ``University of Rome, Tor Vergata'', Rome, Italy in October 2004.

· Delivered a seminar on ``Rolling Brane Dynamics Near NS5-branes'' at Dipartimento di Fisica, Universita di Genova in February 2005.

· 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 2005.

· Delivered a seminar on ``D-branes in cosmological backgrounds'' at ``Institute of Physics'', India in March 2006.

· Delivered a seminar on ``D-brane dynamics'' at ``Institute of Mathematical Sciences'', Chennai, India in March 2006.

· 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 2006.

· Delivered a seminar on ``D-brane statics and Dynamics in Exact string backgrounds’’ at Indian Institute of Technology, Guwahati, India in September 2006.

· Delivered a seminar on ``Lagrangian Formulation of Higher Spin theories on AdS Space’’ at Indian String Meeting (ISM06), Puri India in December 2006.

· 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 2007

· Delivered a Seminar on ``Massless Higher spin theories on AdS’’ at Center for Quantum Spacetime, Sogang University, Seoul in June 2007.

· Delivered a seminar on ``On the geometrical tachyon and universal open string tachyon’’, at Institute of Physics, India in October 2007.

· Delivered a seminar on `` The geometrical tachyon and universal open string tachyon’’, at Saha Institute of Nuclear Physics, in December 2007.

· Delivered a seminar on `` String theory: Is this a theory of everything ?'', at Indian Institute of Science Education and Research (IISER) Kolkata , in February 2008.

· Delivered a seminar on `` Massless Higher Spin theories in AdS space'', at S. N. Bose Centre for Basic Sciences, Kolkata in February 2008.