# M. Ronen Plesser

## Professor of Physics

### Overview

My research is in String Theory, the most ambitious attempt yet at a comprehensive theory of the fundamental structure of the universe. In some (rather imprecise) sense, string theory replaces the particles that form the fundamental building blocks for conventional theories (the fields, or wave phenomena, we observe are obtained starting from particles when we apply the principles of quantum mechanics) with objects that are not point-like but extended in one dimension – strings. At present, the theory is not precisely formulated, as we still seek the conceptual and technical tools needed. The structures we do have in hand suggest that, when formulated precisely, the theory will provide a consistent framework encompassing the two greatest achievements of twentieth century theoretical physics: Einstein’s general theory of relativity, which describes gravitational forces objects in terms of deformations of the geometry of spacetime; and quantum mechanics, a model of fundamental physics in which microscopic objects exhibit the properties of particles under some circumstances and those of waves under others. Both of these theories have been tested with extraordinary precision and yield predictions that agree with our observations of the physical universe. Relativistic effects are manifest at the largest scales in the universe, in the interactions of stars, galaxies, etc. The differences between a quantum mechanical description and a classical nineteenth century description of these objects are so small they can be neglected. Quantum effects dominate at the smallest scales – atoms and their constituents. In this realm, the effects of gravitation can be completely neglected. And yet, under extreme conditions of density, such as may obtain in the final instant of the evaporation of a black hole, both kinds of effects are important. A universal theory of physics thus requires a consistent quantum theory of gravity. Thus far, string theory is the most promising candidate for producing such a theory. Investigations of this theory have already yielded rich insights, and continue to produce more.

My own research centers on the crucial role played in the theory by geometric structures. There is an obvious role for geometry in a theory that incorporates gravitation, which as discussed above is tantamount to the geometry of spacetime. Related to this are several other, less obvious, geometric structures that play an important role in determining the physics of the theory. Indeed, advances in mathematics and in the physics of string theory have often been closely linked. An example of how the two fields have interacted in a surprising way is the ongoing story of mirror symmetry.

### Selected Grants

A Regional Conference Series in Mathematical String Theory awarded by National Science Foundation (Principal Investigator). 2013 to 2019

Moduli Spaces of String Vacua with Four Supersymmetries awarded by National Science Foundation (Principal Investigator). 2015 to 2018

Integrative Middle School STEM Teacher Preparation: A Collaborative Capacity Building Project at Duke University awarded by National Science Foundation (Co Investigator). 2014 to 2017

Geometry and Physics of String Compactifications awarded by National Science Foundation (Principal Investigator). 2012 to 2016

Algebraic Geometry and Quantum Field Theory of D-Branes awarded by National Science Foundation (Co-Principal Investigator). 2006 to 2011

D-Brane Physics and Calabi-Yau Geometry awarded by National Science Foundation (Co-Principal Investigator). 2003 to 2007

Focused Research awarded by National Science Foundation (Co-Principal Investigator). 2000 to 2004

Jockers, H, Katz, S, Morrison, DR, and Plesser, MR. "SU(N) Transitions in M-Theory on Calabi–Yau Fourfolds and Background Fluxes." *Communications in Mathematical Physics* 351.2 (April 2017): 837-871.
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Aspinwall, PS, and Plesser, MR. "General mirror pairs for gauged linear sigma models." *Journal of High Energy Physics* 2015.11 (November 2015).
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Morrison, DR, and Ronen Plesser, M. "Special Lagrangian torus fibrations of complete intersection Calabi–Yau manifolds: A geometric conjecture." *Nuclear Physics B* 898 (September 2015): 751-770.
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Bertolini, M, and Plesser, MR. "Worldsheet instantons and (0,2) linear models." *Journal of High Energy Physics* 2015.8 (August 2015).
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Bertolini, M, Melnikov, IV, and Plesser, MR. "Accidents in (0,2) Landau-Ginzburg theories." *Journal of High Energy Physics* 2014.12 (December 2014).
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Aspinwall, PS, Melnikov, IV, and Ronen Plesser, M. "(0,2) Elephants." *JHEP* 2012 (January 2012): 60-. (Academic Article)
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Aspinwall, PS, Melnikov, IV, and Plesser, MR. "(0,2) elephants." *Journal of High Energy Physics* 2012.1 (2012).
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Kreuzer, M, McOrist, J, Melnikov, IV, and Plesserd, MR. "(0,2) Deformations of linear sigma models." *Journal of High Energy Physics* 2011.7 (2011).
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Melnikov, IV, and Plesser, MR. "A (0,2) mirror map." *Journal of High Energy Physics* 2011.2 (2011).
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Aspinwall, PS, and Plesser, MR. "Decompactifications and massless D-branes in hybrid models." *Journal of High Energy Physics* 2010.7 (2010).
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