Wednesday, September 26th, 2018

Physics Seminar: Cobi Sonnenschein

Time: 1:30 PM - 2:30 PM

Location: SCGP 313

Description:

__Title__: The HISH ( Holography Inspired Stringy Hadron) model and the quantization of a string with massive endpoints

__Abstract__: Holography inspired stringy hadron (HISH) is a model that describes hadrons as strings in four dimensional flat space-time. For mesons, baryons and exotics- open strings with endpoint (massive) particles, and for glueballs- closed strings. In the first part of the talk I will summarize the derivation and the results of the model. In particular the spectra and decay width of hadrons including possible identification of glue-balls and exotic hadrons. I will compare these results with the PDG experimental data. In the second part of the talk I will describe in details the quantization of a string with massive endpoints. This will include the classical solutions of rotating strings and the trans-verse and planar quantum fluctuations in the quadratic approximation. I will introduce an alternative method of renormalizing the system and computing the intercept. Next I will discuss the modification due to the non-criticality of the string and present the HISH Regge-like trajectories. I will determine the OPE of the coordinates of the HISH string. I will present the computation of the hadron strong decay width both the total and partial widths. Preliminary results about scattering amplitudes of HISH strings will be also be described.

**Math Event:**Algebraic Geometry: Aaron Bertram - Stability Conditions on Projective Space.

Time: 4:00 PM - 5:30 PM

Location: Math Tower P-131

Description:

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__Title__: Stability Conditions on Projective Space.

__Speaker__: Aaron Bertram [University of Utah]

__Abstract__: Gieseker stability uses the Hilbert polynomial of a coherent sheaf divided by its leading coefficient as an "asymptotic" slope function. We propose a family of stability conditions on Castelnuovo-Mumford regular sheaves that use the Hilbert polynomial divided by its derivative as "exact" slopes. We conjecture that this converges to Gieseker stability (it's true in dimensions 1,2,3). This is joint work with Matteo Altavilla and Marin Petkovic, and an application to the classification of Gorenstein rings is joint work with Brooke Ullery.

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Thursday, September 27th, 2018

Simons Center Cafe Beer Tasting and Food Pairing

Time: 6:00 PM - 8:00 PM

Location: Simons Center Cafe

Description: Thursday September 27
6 - 8pm
Local Beer and Food Pairings
$35pp, Reservations required
631-632-2881

**Math Event:**Math Colloquium: Boris Bukh - Bipartite Turan problem

Time: 4:00 PM - 5:00 PM

Location: Math Tower P-131

Description:

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__Title__: Bipartite Turan problem

__Speaker__: Boris Bukh [Carnegie Mellon]

__Abstract__: What is the largest graph not containing a copy of a fixed graph H? This question of Turan from 1941 remains open. The most challenging case is when H is bipartite. This case leads to interesting graph embedding problems on one hand, and mysterious algebro-geometric constructions on the other. In the talk, I will discuss the key problems and recent progress in the area.

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Friday, September 28th, 2018

Exactly Solvable Program Seminar: Raphael Nepomechie

Time: 11:00 AM - 12:00 PM

Location: 313

Description:

__Title__: Symmetries and degeneracies of quantum spin chains

__Abstract__: The spectrum of a quantum spin chain can have degeneracies, which can be understood from the model’s symmetries. We consider here the symmetries and degeneracies of anisotropic integrable open spin chains, which are associated to affine Lie algebras $\hat g$. These spin chains have quantum group symmetries corresponding to removing one node from the $\hat g$ Dynkin diagram. Based on recent work with A. Retore (arXiv 1802.04864) and R. Pimenta (arXiv 1805.10144).

**Math Event:**Math Colloquium: Federico Rodriguez Hertz - On the geometry of invariant measures

Time: 4:00 PM - 5:00 PM

Location: SCGP 102

Description:

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__Title__: On the geometry of invariant measures

__Speaker__: Federico Rodriguez Hertz [Penn State University]

__Abstract__: In this talk I will try to explain that, in dynamical systems with some hyperbolicity, some invariant measures present a very nice geometric structure. I also will explain how this geometric structures can be used to recover certain rigidity of the system in study. The goal is to show this approach through examples, so I plan to spend some time describing these examples, their relevant measures and geometry.

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