I work on string theory as applied to black holes, heavy ion collisions, and aspects of condensed matter theory, theoretical cosmology, and number theory.
I focus particularly on the gauge-string duality, which relates gauge theories in four flat spacetime dimensions to string theory in five or ten curved dimensions. The gauge theories that can be described in this way are relatives of quantum chromodynamics, which is the theory of quarks and gluons.
Here are some of the things that I've worked on in recent years:
- Black holes can superconduct.
- Black holes dual to super-Yang-Mills theory at finite chemical potential exhibit Fermi surfaces.
- The motion of vortex rings can be approximately described in terms of bosonic strings in a background field similar to a magnetic field.
- Quarks plowing through a thermal plasma of quarks and gluons lose energy at a rate that can be estimated using strings in anti-de Sitter space.
- Conformal symmetry can be used to help generate exact solutions to the relativistic Navier-Stokes equation that are similar to heavy-ion collisions.
- Classical string theory can sometimes be formulated entirely algebraically, without any calculus.
- There is a version of the gauge-string duality based on the $p$-adic numbers where the bulk geometry is a tree graph.
- O. DeWolfe, S. Gubser, O. Henriksson, and C. Rosen, "Fermionic Response in Finite-Density ABJM Theory with Broken Symmetry," Phys. Rev. D93, 026001, arXiv:1509.00518 [hep-th] (2016).
- S. Gubser, Z. Saleem, S. Schoenholz, B. Stoica, and J. Stokes, "Nonlinear Sigma Models with Compact Hyperbolic Target Spaces," JHEP 06, 145, arXiv:1510.02129 [hep-th] (2016).
- S. Gubser, B. Horn, and S. Parikh, "Perturbations of vortex ring pairs," Phys. Rev. D93, 046001, arXiv:1510.08059 [hep-th] (2016).
- S. Gubser, "Evolution of segmented strings," Phys. Rev. D94, 106007, arXiv:1601.08209 [hep-th] (2016).
- S. Gubser, S. Parikh, and P. Witaszczyk, "Segmented strings and the McMillan map," JHEP 07, 122, arXiv:1602.00679 [hep-th] (2016).
- S. Gubser, J. Knaute, S. Parikh, A. Samberg, and P. Witaszczyk, "$p$-adic AdS/CFT," Commun. Math. Phys. 352, 1019-1059, arXiv:1605.01061 [hep-th] (2017).
- O. DeWolfe, S. Gubser, O. Henriksson, and C. Rosen, "Gapped Fermions in Top-down Holographic Superconductors," Phys. Rev. D95, 086005, arXiv:1609.07186 [hep-th] (2017).
- S. Gubser, M. Heydeman, C. Jepsen, M. Marcolli, S. Parikh, I. Saberi, B. Stoica, and B. Trundy, "Edge length dynamics on graphs with applications to $p$-adic AdS/CFT," JHEP 06, 157, arXiv:1612.09580 [hep-th] (2017).
- S. Gubser, C. Jepsen, S. Parikh, and B. Trundy, "O(N) and O(N) and O(N)" JHEP 11, 107, arXiv:1703.04202 [hep-th] (2017).
- S. Gubser and S. Parikh, "Geodesic bulk diagrams on the Bruhat--Tits tree," Phys. Rev. D96, 066024, arXiv:1704.01149 [hep-th] (2017).
- S. Gubser, "A $p$-adic version of AdS/CFT," arXiv:1705.00373 [hep-th] (2017).
- S. Gubser, M. Heydeman, C. Jepsen, S. Parikh, I. Saberi, B. Stoica, and B. Trundy, "Signs of the time: Melonic theories over diverse number systems," arXiv:1707.01087 [hep-th] (2017).