Professor Liu has numerous theoretical interests, including integrable systems, particle phenomenology, and QCD. Nevertheless, he has focused his research on string theory and M-theory. He has made important contributions to the study of solitons and black holes in string theory, with particular emphasis on dualities connecting various string theories and compactifications into a single unified framework. These include the study of H-monopoles (a name coined by Gauntlett, Harvey and Liu) as well as the explanation for string/string duality based on M2/M5-duality (in work with Duff and Minasian). This latter development opened the door to eleven dimensions and was one of the important milestones in the formulation of M-theory.
Overall, Professor Liu has worked extensively on supergravity solutions and their spacetime properties. He has constructed explicit monopole and brane solutions, and has used them as a means of testing various duality conjectures. Professor Liu has also focused his work on consistent Kaluza-Klein reductions and on lifting solutions to ten or eleven dimensions as a means of identifying their fundamental nature in terms of the building blocks of M-theory. Such investigations of explicit solutions and supergravity fields in nontrivial backgrounds have played important roles throughout the exploration of AdS/CFT duality and holography.
Professor Liu's current interests involve generalizations of AdS/CFT as well as braneworlds and warped geometries. For the latter, he hopes to develop a closer connection between supersymmetric braneworld scenarios and M-theory. Along these lines, he is exploring the holography of bulk spaces with a cutoff as well as the consistent trapping of bulk matter on the brane. Professor Liu believes this direction of research may have important consequences for M-theory, and likes to ponder the fate of extra dimensions in the universe.
A New Fractional D2-Brane, G2 Holonomy and T-Duality, (M. Cvetic, G.W. Gibbons, J.T. Liu, H. Lu and C.N. Pope), Class. Quant. Grav. 19, 5163 [arXiv:hep-th/0106162] (2002).
Quantum Discontinuity Between Zero and Infinitesimal Graviton Mass With a Lambda Term, (F.A. Dilkes, M.J. Duff, J.T. Liu and H. Sati), Phys. Rev. Lett. 87, 041301 [arXiv:hep-th/0102093] (2001).
Complementarity of the Maldacena and Randall-Sundrum Pictures, (M.J. Duff and J.T. Liu), Phys. Rev. Lett. 85, 2052 [arXiv:hep-th/0003237] (2000).
The Transition Temperature to the Superconducting Phase of QCD at High Baryon Density, (W.E. Brown, J.T. Liu and H.C. Ren), Phys. Rev. D 62, 054016 [arXiv:hep-ph/9912409] (2000).
Embedding AdS Black Holes in Ten and Eleven Dimensions, (M. Cvetic et al.), Nucl. Phys. B 558, 96 [arXiv:hep-th/9903214] (1999).
Eleven-Dimensional Origin of String/String Duality: A One-Loop Test, (M.J. Duff, J.T. Liu and R. Minasian), Nucl. Phys. B 452, 261 [arXiv:hep-th/9506126] (1995).
Magnetic Monopoles in String Theory, (J.P. Gauntlett, J.A. Harvey and J.T. Liu), Nucl. Phys. B 409, 363 [arXiv:hep-th/9211056] (1993).