Southeastern regional
mathematical string theory meeting

Next meeting:

Speakers tentatively include Hector Parra de Freitas (Harvard), Natalie Paquette (University of Washington Seattle), Diana Vaman (UVA), Sunit Patil (VT), Alonso Perez-Lona (VT).

Schedule:

• Friday November 8: Optional informal dinner at Sitar Indian Cuisine at 3630 Durham Chapel Hill Blvd, Durham NC. If you wish to join us, aim to be there by 7:45 - 8 pm, and please let Eric Sharpe know by Thurs Nov 7 around lunchtime so that he can make a reservation.

• Saturday November 9: All talks will be in room Physics 130.
  • 10:00-11:00: Natalie Paquette (University of Washington Seattle), "Top-down holography in an asymptotically flat spacetime"
    • Abstract: I will describe a construction of a simple duality between a 2d chiral CFT and a certain 4d theory on an asymptotically Euclidean spacetime called Burns space. This duality arises from studying the topological type I string on Penrose's twistor space, and is an example of what is often called "twisted holography". We will discuss the derivation of this duality and some of its basic properties.

  • 11:15-12:15: Hector Parra de Freitas (Harvard), "Symmetry enhancements in non-SUSY heterotic strings with reduced rank"
    • Abstract: I will discuss symmetry enhancements in four non-supersymmetric heterotic strings with reduced rank in dimensions D = 8,9,10 and their torus compactifications. All of these arise as heterotic orbifolds by symmetries involving Z2 involutions on the gauge bundle, trading e.g. the two factors of E8xE8 or O(16)xO(16). Each of them has a distinct tree-level moduli space with its own patterns of non-Abelian gauge symmetry enhancements as well as matter/tachyon content. I'll show how these enhancements can be obtained systematically and how they can be related across different perturbative theories (in a way that seems to be non-perturbative). I'll discuss how the analysis/classification of enhancements can be applied to the characterization of 1-loop potential extrema (when applicable), as well as matching "moduli" between duality frames.

  • 12:30-2:00: lunch

  • 2:00-3:00: Diana Vaman (UVA), "Classical limit, worldline formalism and a proof of eikonal exponentiation"
    • Abstract: In this talk I will focus on 2 body scattering processes mediated by massless force carriers. On the one hand, taking the classical limit of the QFT scattering amplitude leads to the eikonal method. On the other hand, since in the classical limit the scattering particles are almost on-shell throughout the scattering process, the worldline, a first quantized formalism, is the most efficient framework to study the scattering amplitude. This is an alternate but equivalent formalism to the quantum field theoretic (QFT) framework. By taking the classical limit of the scattering amplitude computed in the worldline, we can derive the WQFT rules of Mogull, Plefka and Steinhoff. In WQFT, the Feynman diagrams are reorganized into a new set of diagrams that facilitate the ℏ expansion. Unlike the QFT eikonal method, which works recursively in identifying the eikonal phase, the worldline-based computation allows to target and systematically extract the classical contributions directly through a specific set of WQFT diagrams. In worldline formalism, the perturbative expansion of the scattering amplitude is naturally organized in diagrams which factorize (reducible) and diagrams which are new to that order (irreducible), in a one-to-one map with the structure of the amplitude in the eikonal method. This leads to a straightforward proof the conjectured exponentiation of the eikonal phase to all orders.

  • 3:15-3:45: Sunit Patil (VT), "Conifold Transitions and Possible New Dualities in 4D N=1 Theories"
    • Abstract: Geometric transitions between Calabi-Yau threefolds have long been of interest in string compactifications. However, the physical/geometrical understanding of such transitions has been primarily limited to 4D, N=2 compactifications. It is of interest to understand such transitions in the context of 4D, N=1 theories. Recent work in heterotic theories has shed some light on the geometry of transitions involving not only Calabi-Yau threefolds, but also vector bundles or branes. I will discuss recent progress in this program by describing a field map between two potentially dual 4D, N=1 heterotic theories. We explore how holomorphic functions in the equivalence classes of complex structure, Kähler, and bundle (brane) moduli map through the transition. Yukawa couplings in the perturbative superpotential are calculated on both sides of the transition and matched using the derived moduli map, serving as a consistency check.
    • slides

  • 3:45-4:15: Alonso Perez-Lona (VT), "Discrete torsion in gauging non-invertible symmetries"
    • Abstract: We discuss two complementary generalizations of discrete torsion to noninvertible symmetries in 2d QFTs. Both generalizations are counted by group cohomology when one specializes to ordinary finite group symmetries. However, the counting is different for more general fusion categories. Furthermore, only one generalizes the picture of discrete torsion as differences in choices of gauge actions on B fields, as originally observed for ordinary orbifolds with B fields. We also explain how this same generalization of discrete torsion gives rise to physically-sensible twists on gaugeable algebras and fiber functors.
    • slides
• Group photos here, here.

Discrimination / diversity:

If you are an individual with a disability and desire an accommodation, please contact Eric Sharpe (VT office phone 540-381-0185) at least 10 business days prior to the event.

Coffee:

• There are two coffee shops in the Bryan Center.
• Another coffee shop, ``Twinnies,'' is located in the Fitzpatrick Center.
• Coffee is served in the LSRC cafeteria.
• There is a coffee shop in the Perkins Library.

For visitors to the area:

• For those flying in, the closest airport is Raleigh-Durham International (RDU).
• A map of Duke's campus can be found here.
• We will try to obtain parking passes for the lot beside the physics department building, email Eric Sharpe for such a pass if you will drive in.
• If you don't have a pass, convenient visitor parking at Duke can often (though not always) be found in the parking deck behind the Bryan Center, off of Science Drive. On rare occasion, that parking deck may be closed or full. In such an event, there is a visitor information center located at the traffic circle on Towerview Road, and the staff there can provide other visitor parking options. (For example, there is a parking deck on Erwin Road, across from the main entrance to the hospital -- but getting from there to the physics department is nontrivial.) Alternatively, see here for a comprehensive list of Duke visitor parking options.
• For those driving in from out of town, it should be noted that I-40 typically gets jammed with RTP traffic during morning and afternoon rush hours.

Funding:

Previous regional meetings:

Other upcoming meetings of interest:

Raleigh-Durham area attractions:

• Overview of Durham attractions
• Morehead Planetarium in Chapel Hill,
• There is a small Museum of NC history on the UNC-CH campus.
• Nasher Museum of Art at Duke University, open late on Thursday evenings,
• NC Museum of Art in Raleigh,
• NC Museum of Natural Sciences
• NC Museum of History
• Reader's Corner, a used book store on Hillsborough St. in Raleigh,
• Nice Price Books, another used book store on Hillsborough St. in Raleigh,
• Other Raleigh events held on the first Friday of every month are listed here,
• Full Frame Documentary Film Festival, held in April of each year.
• Events in Chapel Hill are often listed here.