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- Steven B Giddings, Shamit Kachru, Joseph Polchinski
- 2001

Warped compactifications with significant warping provide one of the few known mechanisms for naturally generating large hierarchies of physical scales. We demonstrate that this mechanism is realizable in string theory, and give examples involving orientifold compactifications of IIB string theory and F-theory compactifications on Calabi-Yau four-folds. In… (More)

- Shamit Kachru, Cumrun Vafa
- 1995

We search for N = 2, d = 4 theories which can be realized both as heterotic string compactifications on K 3 × T 2 and as type II string compactifications on Calabi-Yau three-folds. In such cases, the exact non-perturbative superpotential of one string theory is given in terms of tree level computations in the other string theory. In particular we find… (More)

- Shamit Kachru, Renata Kallosh, Juan Maldacena, Liam Mcallister, Sandip P Trivedi
- 2003

We investigate the embedding of brane inflation into stable compactifications of string theory. At first sight a warped compactification geometry seems to produce a naturally flat inflaton potential, evading one well-known difficulty of brane-antibrane scenarios. Careful consideration of the closed string moduli reveals a further obstacle: superpotential… (More)

- Xingang Chen, Min-Xin Huang, Shamit Kachru, Gary Shiu
- 2008

We perform a general study of primordial scalar non-Gaussianities in single field inflationary models. We consider models where the inflaton Lagrangian is an arbitrary function of the scalar field and its first derivative, and the sound speed is arbitrary. We find that under reasonable assumptions, the non-Gaussianity is completely determined by 5… (More)

- Shamit Kachru, Michael Schulz, Sandip P Trivedi, January
- 2002

We study novel type IIB compactifications on the T 6 /Z 2 orientifold. This geometry arises in the T-dual description of Type I theory on T 6 , and one normally introduces 16 space-filling D3-branes to cancel the RR tadpoles. Here, we cancel the RR tadpoles either partially or fully by turning on three-form flux in the compact geometry. The resulting… (More)

- Shamit Kachru, Xiao Liu, Michael Mulligan
- 2008

We find candidate macroscopic gravity duals for scale-invariant but non-Lorentz invariant fixed points, which do not have particle number as a conserved quantity. We compute two-point correlation functions which exhibit novel behavior relative to their AdS counterparts, and find holographic renormalization group flows to conformal field theories. Our… (More)

- Shamit Kachru, Eva Silverstein
- 1998

We propose correspondences between 4d quantum field theories with N = 2, 1, 0 (super)conformal invariance and Type IIB string theory on various orbifolds of AdS 5 × S 5. We argue using the spacetime string theory, and check using the beta functions (exactly for N = 2, 1 and so far at 1-loop for the gauge couplings in the N = 0 case), that these theories… (More)

- Oliver Dewolfe, Alexander Giryavets, Shamit Kachru, Washington Taylor
- 2005

We demonstrate that flux compactifications of type IIA string theory can classically stabilize all geometric moduli. For a particular orientifold background, we explicitly construct an infinite family of supersymmetric vacua with all moduli stabilized at arbitrarily large volume, weak coupling, and small negative cosmological constant. We obtain these… (More)

- Shamit Kachru, Michael B Schulz, Prasanta K Tripathy, Sandip P Trivedi
- 2002

We describe a new class of supersymmetric string compactifications to 4d Minkowski space. These solutions involve type II strings propagating on (orientifolds of) non Calabi-Yau spaces in the presence of background NS and RR fluxes. The simplest examples have descriptions as cosets, generalizing the three-dimensional nilmanifold. They can also be thought of… (More)

- Mark P Hertzberg, Shamit Kachru, Washington Taylor, Max Tegmark
- 2007

We prove that inflation is forbidden in the most well understood class of semi-realistic type IIA string compactifications: Calabi-Yau compactifications with only standard NS-NS 3-form flux, R-R fluxes, D6-branes and O6-planes at large volume and small string coupling. With these ingredients, the first slow-roll parameter satisfies ǫ ≥ 27 13 whenever V > 0,… (More)