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Sudhakar Panda
Research Summary:
We investigated the effective action of the tachyon field on a D-brane,
of both bosonic as well as superstring theory. It is found that
the non-standard kinetic term of the tachyon field requires a correction
to the Dirac-Born-Infeld Lagrangian. Using the tachyon potential,
derived in boundary string field theory, the dynamics of the rolling
tachyon was studied in the context of inflationary scenario in cosmology
(work with D. Choudhury, D. Ghoshal and D.P. Jatkar).
The bosonic string theory is formulated in the background of generic
electromagnetic field and its quantum dynamics is studied. For specific
configurations of the background electric and magnetic fields the
thermodynamical properties of the system, in the gravity decoupling
limit, are studied (work with S. Kar).
We ahve constructed the action for N-coincident D0-branes which
is targetspace supersymmetric and invariant under local world line
fermionic kappa-symmetry in D-dimensional N=2 superspace. The action
has a generic structure determined by a super- and kappa-invariant
effective mass which is a generic function of SU(N) fields of the
theory and their momenta and which also depends on the spatial momentum
of the center of mass of the system. Comparision has been made for
the ND0-brane action with that of Matrix theory (work with S.S.
Pal and D. Sorokin).
The scalar potential of gauged N=4 supergravity with matter is
studied. The constriants on the matter scalars are solved in terms
of an explicit parametrisation of an SO(6, 6+n) element. In a particular
example of noncompact groups and four scalars, we find a potential
with an absolute minimum and a positive cosmological constant (work
with M. deRoo and D. B. Westra).
Publications:
(1) Choudhury D., Ghoshal D, Jatkar D.P. and Panda S., On the
Cosmological Relevance of the Tachyon, PHys. Lett. B544 (2002) 231.
(2) Kar S. and Panda S., Electromagnetic Strings: complimentarity
between time and temperature, JHEP 11 (2002) 052.
(3) de Roo M., Panda S. and Westra D.B., De Sitter solution in
N=4 matter coupled supergravity, JHEP 02 (2003) 003.
(4) Panda S. and Sorokin D., Supersymmetric and Kappa-invariant
coincident D0-branes, JHEP 02 (2003) 055.
Preprints:
(1) On the Cosmological Relevance of the Tachyon, D. Choudhury,
D. Ghoshal, D.P. Jatkar and S. Panda, hep-th/0204204.
(2) Electromagnetic Strings: complimentarity between time and
temperature, S. Kar and S. Panda, hep-th/0205078.
(3) Coincident Dp-branes in codimension two, S.S. Pal and S. Panda,
hep-th/0211115.
(4) De Sitter solution in N=4 matter coupled supergravity, M.
de Roo, S. Panda and D.B. Westra, hep-th/0212216.
(5) Supersymmetric and Kappa-invariant coincident D0-branes, S.
Panda and D. Sorokin, hep-th/0301065.
Conference/Workshops Attended:
(1) International Workshop on String Theory, HRI, Allahabad (2002).
(2) PASCOS-2003, TIFR, Mumbai (2003).
(3) Workshop on String Theory, IACS, Kolkata (2003).
Visits to other Institutes:
(1) BITS, Pilani (2002).
(2) University of Groningen, The Netherlands (2002).
(3) TIFR, Mumbai (2003).
(4) IACS, Kolkata (2003).
Invited Lectures/Seminars:
(1) Pulling the World with Strings; BITS, Pilani.
(2) Tachyon Condensation and Cosmology; Univ. of Groningen, The
Netherlands.
(3) De Sitter solution in gauged N=4 supergravity; IACS, Kolkata.
(4) Unification of Interaction in Nature; IERT, Allahabad.
(5) What is String Theory; IERT, Allahabad.
Other Activities:
Organiser, Intrnational Workshop on String Theory, HRI, Allahabad.
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