The Double Life of Thermal QCD (2009)
Mia, Mohammed, Dasgupta, Keshav, Gale, Charles, Jeon, Sangyong
We study the gravity dual of a thermal gauge theory whose behavior parallels that of thermal QCD in the far IR. The UV of our theory has infinite degrees of freedom. We holographically renormalize...
Five Easy Pieces: The Dynamics of Quarks in Strongly Coupled Plasmas (2009)
Mia, Mohammed, Dasgupta, Keshav, Gale, Charles, Jeon, Sangyong
We revisit the analysis of the drag a massive quark experiences and the wake it creates at a temperature T while moving through a plasma using a gravity dual that captures the renormalisation group...
Magnetic Fields from Heterotic Cosmic Strings (2008)
Gwyn, Rhiannon, Alexander, Stephon, Brandenberger, Robert H., Dasgupta, Keshav
Large-scale magnetic fields are observed today to be coherent on galactic scales. While there exists an explanation for their amplification and their specific configuration in spiral galaxies -- the...
On The Warped Heterotic Axion (2008)
Dasgupta, Keshav, Firouzjahi, Hassan, Gwyn, Rhiannon
We study the axion in a warped heterotic background. It is shown that the axion decay constant, f_a, is sensitive to the warped mass scale of the throat. As an explicit model, we construct a novel...
D-terms on the resolved conifold (2008)
Dasgupta, Keshav, Franche, Paul, Knauf, Anke, Sully, James
We derive a novel deformation of the warped resolved conifold background with supersymmetry breaking ISD (1,2) fluxes by adding D7-branes to this type IIB theory. We find spontaneous supersymmetry...
A Study of Structure Formation and Reheating in the D3/D7 Brane Inflation Model (2008)
Brandenberger, Robert H., Dasgupta, Keshav, Davis, Anne-Christine
We study the spectrum of cosmological fluctuations in the D3/D7 brane inflationary universe with particular attention to the parametric excitation of entropy modes during the reheating stage. The...
Quaternionic Kahler Manifolds, Constrained Instantons and the Magic Square: I (2007)
Dasgupta, Keshav, Hussin, Veronique, Wissanji, Alisha
The classification of homogeneous quaternionic manifolds has been done by Alekseevskii, Wolf et al using transitive solvable group of isometries. These manifolds are not generically symmetric, but...
Dasgupta, Keshav, Firouzjahi, Hassan, Gwyn, Rhiannon
We study classical lump solutions in a warped throat where brane inflation takes place. Some of the solitonic or lump solutions that we study here are the (p,q) cosmic strings and their junctions,...
Uplifting and Inflation with D3 Branes (2006)
Burgess, Cliff P., Cline, James M., Dasgupta, Keshav, Firouzjahi, Hassan
Back-reaction effects can modify the dynamics of mobile D3 branes moving within type IIB vacua, in a way which has recently become calculable. We identify some of the ways these effects can alter...
Dipole-Deformed Bound States and Heterotic Kodaira Surfaces (2006)
Dasgupta, Keshav, Guffin, Josh, Gwyn, Rhiannon, Katz, Sheldon
We study a particular N = 1 confining gauge theory with fundamental flavors realised as seven branes in the background of wrapped five branes on a rigid two-cycle of a non-trivial global geometry. In...
Gauge-Gravity Dualities, Dipoles and New Non-Kahler Manifolds (2006)
Dasgupta, Keshav, Grisaru, Marc, Gwyn, Rhiannon, Katz, Sheldon, Knauf, Anke, Tatar, Radu
In this work we explore many directions in the framework of gauge-gravity dualities. In type IIB theory we give an explicit derivation of the local metric for five branes wrapped on rigid two-cycles....
Geometric Transitions, Flops and Non-Kahler Manifolds: II (2005)
Becker, Melanie, Dasgupta, Keshav, Katz, Sheldon, Knauf, Anke, Tatar, Radu
We continue our study of geometric transitions in type II and heterotic theories. In type IIB theory we discuss an F-theory setup which clarifies many of our earlier assumptions and allows us to...
Brane Inflation, Solitons and Cosmological Solutions: I (2005)
Chen, Pisin, Dasgupta, Keshav, Narayan, K., Shmakova, Marina, Zagermann, Marco
In this paper we study various cosmological solutions for a D3/D7 system directly from M-theory with fluxes and M2-branes. In M-theory, these solutions exist only if we incorporate higher derivative...
Geometric Transitions, Non-Kahler Geometries and String Vacua (2004)
Becker, Katrin, Becker, Melanie, Dasgupta, Keshav, Tatar, Radu
We summarize an explicit construction of a duality cycle for geometric transitions in type II and heterotic theories. We emphasize that the manifolds with torsion constructed with this duality cycle...
In the Realm of the Geometric Transitions (2004)
Alexander, Stephon, Becker, Katrin, Becker, Melanie, Dasgupta, Keshav, Knauf, Anke, Tatar, Radu
We complete the duality cycle by constructing the geometric transition duals in the type IIB, type I and heterotic theories. We show that in the type IIB theory the background on the closed string...
D3/D7 Brane Inflation and Semilocal Strings (2004)
Dasgupta, Keshav, Hsu, Jonathan P., Kallosh, Renata, Linde, Andrei, Zagermann, Marco
Among the inflationary models based on string theory, the D3/D7 model has the advantage that the flatness of the inflaton potential can be protected even with moduli stabilization. However, the...
Geometric Transitions, Flops and Non-Kahler Manifolds: I (2004)
Becker, Melanie, Dasgupta, Keshav, Knauf, Anke, Tatar, Radu
We construct a duality cycle which provides a complete supergravity description of geometric transitions in type II theories via a flop in M-theory. This cycle connects the different supergravity...
Kahler versus Non-Kahler Compactifications (2003)
Becker, Melanie, Dasgupta, Keshav
We review our present understanding of heterotic compactifications on non-Kahler complex manifolds with torsion. Most of these manifolds can be obtained by duality chasing a consistent F-theory...
Compactifications of Heterotic Strings on Non-Kahler Complex Manifolds: II (2003)
Becker, Katrin, Becker, Melanie, Dasgupta, Keshav, Green, Paul S., Sharpe, Eric
We continue our study of heterotic compactifications on non-Kahler complex manifolds with torsion. We give further evidence of the consistency of the six-dimensional manifold presented earlier and...
On Branes and Oriented B-fields (2003)
Dasgupta, Keshav, Shmakova, Marina
Novel theories appear on the world-volume of branes by orienting B fields along various directions of the branes. We review some of the earlier developments and explore many new examples of these...
Properties Of Heterotic Vacua From Superpotentials (2003)
Becker, Katrin, Becker, Melanie, Dasgupta, Keshav, Prokushkin, Sergey
We study the superpotential for the heterotic string compactified on non-Kahler complex manifolds. We show that many of the geometrical properties of these manifolds can be understood from the...
Time-Dependent Warping, Fluxes, and NCYM (2003)
Dasgupta, Keshav, Rajesh, Govindan, Robbins, Daniel, Sethi, Savdeep
We describe the supergravity solutions dual to D6-branes with both time-dependent and time-independent B-fields. These backgrounds generalize the Taub-NUT metric in two key ways: they have asymmetric...
Compactifications of Heterotic Theory on Non-Kahler Complex Manifolds: I (2003)
Becker, Katrin, Becker, Melanie, Dasgupta, Keshav, Green, Paul S.
We study new compactifications of the SO(32) heterotic string theory on compact complex non-Kahler manifolds. These manifolds have many interesting features like fewer moduli, torsional constraints,...
Heterotic Strings with Torsion (2002)
Becker, Katrin, Dasgupta, Keshav
In this paper we describe the heterotic dual of the type IIB theory compactified to four dimensions on a toroidal orientifold in the presence of fluxes. The type IIB background is most easily...
Protected Multiplets of M-Theory on a Plane Wave (2002)
Dasgupta, Keshav, Sheikh-Jabbari, Mohammad M., Van Raamsdonk, Mark
We show that the symmetry algebra governing the interacting part of the matrix model for M-theory on the maximally supersymmetric pp-wave is the basic classical Lie superalgebra SU(4|2). We determine...
Matrix Perturbation Theory For M-theory On a PP-Wave (2002)
Dasgupta, Keshav, Sheikh-Jabbari, Mohammad M., Van Raamsdonk, Mark
In this paper, we study the matrix model proposed by Berenstein, Maldacena, and Nastase to describe M-theory on the maximally supersymmetric pp-wave. We show that the model may be derived directly as...
D3/D7 Inflationary Model and M-theory (2002)
Dasgupta, Keshav, Herdeiro, Carlos, Hirano, Shinji, Kallosh, Renata
A proposal is made for a cosmological D3/D7 model with a constant magnetic flux along the D7 world-volume. It describes an N=2 gauge model with Fayet-Iliopoulos terms and the potential of the hybrid...
Geometric Transition versus Cascading Solution (2001)
Dasgupta, Keshav, Oh, Kyungho, Park, Jaemo, Tatar, Radu
We study Vafa's geometric transition and Klebanov - Strassler solution from various points of view in M-theory. In terms of brane configurations, we show the detailed equivalences between the two...
Open/Closed String Dualities and Seiberg Duality from Geometric Transitions in M-theory (2001)
Dasgupta, Keshav, Oh, Kyungho, Tatar, Radu
We propose a general method to study open/closed string dualities from transitions in M theory which is valid for a large class of geometrical configurations. By T-duality we can transform...
Geometric Transition, Large N Dualities and MQCD Dynamics (2001)
Dasgupta, Keshav, Oh, Kyungho, Tatar, Radu
We study Vafa's geometric transition from a brane setup in M-theory. In this transition D5 branes wrapped on P^1 cycles of a resolved conifold disappear and are replaced by fluxes on a deformed...
Nonlocal Field Theories and their Gravity Duals (2001)
Bergman, Aaron, Dasgupta, Keshav, Ganor, Ori J., Karczmarek, Joanna L., Rajesh, Govindan
The gravity duals of nonlocal field theories in the large N limit exhibit a novel behavior near the boundary. To explore this, we present and study the duals of dipole theories - a particular class...
Spatial noncommutativity is similar and can even be related to the non-Abelian nature of multiple D-branes. But they have so far seemed independent of each other. Reflecting this decoupling, the...
Conifolds with Discrete Torsion and Noncommutativity (2000)
Dasgupta, Keshav, Hyun, Seungjoon, Oh, Kyungho, Tatar, Radu
We study D3 branes at orbifolded conifold singularities in the presence of discrete torsion. The vacuum moduli space of open strings becomes non-commutative due to a deformation of the superpotential...
Noncommutative Tachyons (2000)
Dasgupta, Keshav, Mukhi, Sunil, Rajesh, Govindan
When unstable Dp-branes in type II string theory are placed in a B-field, the resulting tachyonic world-volume theory becomes noncommutative. We argue that for large noncommutativity parameter,...
Pinned Branes and New Non Lorentz Invariant Theories (2000)
Chakravarty, Shoibal, Dasgupta, Keshav, Ganor, Ori J., Rajesh, Govindan
We describe a mechanism for localising branes in ambient space. When a 3-form flux is turned on in a Taub-NUT space, an M5-brane gets an effective potential that pins it to the center of the space. A...
M Theory, Orientifolds and G-Flux (1999)
Dasgupta, Keshav, Rajesh, Govindan, Sethi, Savdeep
We study the properties of M and F theory compactifications to three and four dimensions with background fluxes. We provide a simple construction of supersymmetric vacua, including some with...
Brane Constructions, Fractional Branes and Anti-deSitter Domain Walls (1999)
Dasgupta, Keshav, Mukhi, Sunil
Compactifications of type IIB string theory on AdS5 x X5, where X5 is an Einstein space, can have one-fourth or half maximal supersymmetry for certain choices of X5. Some of these theories admit...
Brane mapping under $(-1)^{F_L}$ (1999)
We present the evidence that $(-1)^{F_L}$ is a nonperturbative symmetry of Type II string theory. We argue that $(-1)^{F_L}$ is a symmetry of string theory as much as the $SL(2, Z)$ of the Type II...
Brane Constructions, Conifolds and M-Theory (1998)
Dasgupta, Keshav, Mukhi, Sunil
We show that a set of parallel 3-brane probes near a conifold singularity can be mapped onto a configuration of intersecting branes in type IIA string theory. The field theory on the probes can be...
BPS Nature of 3-String Junctions (1997)
Dasgupta, Keshav, Mukhi, Sunil
We study BPS-saturated classical solutions for the world-sheet theory of a D-string in the presence of a point charge. These solutions are interpreted as describing planar 3-string junctions, which...
Anomaly Inflow on Orientifold Planes (1997)
Dasgupta, Keshav, Mukhi, Sunil
We examine some six-dimensional orientifold models with $N = 1$ supersymmetry, which can be realised as intersecting 7-branes and 7-planes. These models are studied in the light of recent work...
Gravitational Couplings and $Z_2$ Orientifolds (1997)
Dasgupta, Keshav, Jatkar, Dileep P., Mukhi, Sunil
The interplay between gravitational couplings on branes and the occurrence of fractional flux in low dimensional orientifolds is examined. It is argued that gravitational couplings need to be...
A Note on Low-Dimensional String Compactifications (1996)
Dasgupta, Keshav, Mukhi, Sunil
We study supersymmetric compactifications of type II strings on eightfolds to two dimensions. It is demonstrated that the type IIB string on an eightfold is free of gravitational anomalies. T-duality...
F-Theory at Constant Coupling (1996)
Dasgupta, Keshav, Mukhi, Sunil
The subspace of the moduli space of F-theory on K3 over which the coupling remains constant develops new branches at special values of this coupling. These values correspond to fixed points under the...
Dasgupta, Keshav, Mukhi, Sunil
We study Z2-orbifolds of 11-dimensional M-theory on tori of various dimensions. The most interesting model (besides the known S1/Z2 case) corresponds to T5/Z2, for which we argue that the resulting...