Louis Leblond

Louis Leblond's picture
Pennsylvania State University

Areas of Research:

Research Interests

I work at the interface between high-energy physics, string theory and cosmology with particular interest in theories of the early Universe. Recently, I have been studying quantum effects from interacting fields in spacetimes where the rate of expansion accelerates. In the context of inflation, this is the basic theory from which we can calculate deviations from Gaussianity. Various ongoing missions are constraining this fundamental characteristic of primordial perturbations. More speculatively, I have been looking for possible sensitivity to initial conditions through infrared effects. If present, this persistence of memory goes against the standard folklore that inflation is insensitive to initial conditions and it may also provide a natural explanation for the smallness of the measured value of the dark energy today. Finally, I also work on topological defects and their high energy signatures such as gravitational wavebursts from cosmic strings.

Positions Held

  • 2006-2009 Postdoc Research Associate, Mitchell Institute for Fundamental Physics, Texas A&M University, USA

Recent Publications

  • A. Klimek, L. Leblond, A.Sinha, Cavitation in holographic sQGP, Phys. Lett. B701, 144-150 (2011), arXiv: 1103.3987
  • L. Leblond and E. Pajer, Resonant Trispectrum and a Dozen More Primordial N-point functions, JCAP 1101, 035 (2011), arXiv: 1010.4565 [hep-th]
  • C. Burgess, R. Holman, L. Leblond and S. Shandera, Breakdown of Semiclassical Methods in de Sitter Space, JCAP 1010 017 (2010), arXiv: 1005.3551 [hep-th]
  • J. Kumar, L. Leblond and A. Rajaraman, Constructing Infrared Finite Propagators in Inflating Spacetime, Phys.Rev. D82 (2010) 023525, arXiv: 1002.4214
  • C.P. Burgess, L. Leblond, R. Holman, S. Shandera, Super-Hubble de Sitter Fluctuations and the Dynamical RG, JCAP 1003:033,2010, arXiv: 0912.1608
  • J. Kumar, L. Leblond and A. Rajaraman, Scale Dependent Local Non-Gaussianity from Loops. JCAP 1004, 024 (2010), arXiv: 0909.2040
  • B. Dutta, L. Leblond and K. Sinha, Mirage in the Sky: Non-thermal Dark Matter, Gravitino Problem, and Cosmic Ray Anomalies, Phys. Rev. D 80, 035014 (2009), arXiv: 0904.3773 [hep-ph].
  • L. Leblond, B. Shlaer and X. Siemens, Gravitational Waves from Broken Cosmic Strings: The Bursts and the Beads, Phys. Rev. D 79, 123519 (2009) arXiv: 0903.4686 [astro-ph.CO].
  • B. Dutta, L. Leblond and J. Kumar, Tachyon Mediated Non-Gaussianity, Phys. Rev. D 78, 083522 (2008), arXiv: 0805.1229 [hep-th].
  • L. Leblond and S. Shandera, Simple Bounds from the Perturbative Regime of Inflation, JCAP 0808, 007 (2008), arXiv: 0802.2290 [hep-th].
  • M. Becker, L. Leblond and S. E. Shandera, Inflation from Wrapped Branes, Phys. Rev. D 76, 123516 (2007), arXiv: 0709.1170 [hep-th].
  • B. Dutta, J. Kumar and L. Leblond, An Inflationary Scenario in Intersecting Brane Models, JHEP 0707, 045 (2007), hep-th/0703278
  • L. Leblond and M. Wyman, Cosmic Necklaces from String Theory, Phys. Rev. D 75, 123522 (2007), astro-ph/0701427
  • On the Decay of Massive Fields in de Sitter, D. P. Jatkar, L. Leblond, A. Rajaraman, arXiv: 1107.3513.
  • Breakdown of Semiclassical Methods in de Sitter Space, C.P. Burgess, R. Holman, L. Leblond, S. Shandera, arXiv: 1005.3551


  • Resumming late time divergences, Cornell University
  • Beyond Tree Level Inflation, DAMTP, Cambridge University, UK
  • Infrared Effects and Resummation in de Sitter, Workshop on Effective Field Theory in Cosmology, Ann Arbor, MI
  • Loop Correction to Cosmological Correlation Function, Fundamental Aspect of String Theory Workshop, KITP, Santa Barbara
  • Quantum Loops in de Sitter, Workshop on High Energy Phenomenology, Cook's Branch Conservancy, Texas.
  • Tachyon Mediated Non-Gaussianity, Cosmo 08, Madison
  • Inflation from Wrapped Branes, String Phenomenology 2008, UPenn, Philadelphia
  • Inflation from Branes Pascos 07, Imperial College, UK
  • PIRSA:11070031, From the biggest things to the Biggest Bang, 2011-07-13, EinsteinPlus 2011. Talk for a broad audience of non-scientists.
  • PIRSA:10050010, Eternal Inflation, 2010-05-03, Cosmology Mini Course
  • PIRSA:09050062, Perturbative Bounds in Inflation & Quantum Loops, 2009-05-22, Effective Field Theories in Inflation
  • PIRSA:08060163, Limits from the Perturbative Regime of Inflation and Non-Gaussianity, 2008-06-05, PASCOS 08
  • PIRSA:06100020, Bound State of Cosmic Superstrings in Curved Geometry, 2006-10-24, Cosmology