Mar 07 (Fri)
13:00 MCS0001 HEPMMax Elliot Huebner (Uppsala University): Non-Supersymmetric Orbifolds, Quivers and Chen-Ruan Orbifold Cohomology
We consider D3-brane probes of non-supersymmetric orbifolds and IIA on the same class of non-supersymmetric orbifolds. Both setups are characterized, in part, by quivers (which in the latter case relate for example to D0-brane probes) from which symmetries constraining the scale-dependence and tachyonic instabilities of the two systems, respectively, can be derived. We demonstrate that these considerations can be matched via a geometric analysis of the asymptotic boundary of the relevant orbifolds, in all cases, via considerations centered on Chen-Ruan orbifold cohomology.
Venue: MCS0001
Mar 10 (Mon)
12:00 MCS0001 PureKaren Vogtmann (University of Warwick): Moduli spaces of tori, graphs and other RAAG-complexes
The classical symmetric space for the general linear group
is a contractible space on which the outer automorphism group Out(Z^n)
of a free abelian group (otherwise known as GL(n,Z)) acts with finite
stabilizers. Classical Outer space is a contractible space on which the
group Out(F_n) of outer automorphisms of a non-abelian free group acts
with finite stabilizers. These outer automorphism groups pop up in
diverse areas of mathematics, and studying these spaces has been a very
effective way to discover features of the groups. In this talk I will
first review these spaces, which are spaces of tori and graphs, then
introduce right-angled Artin groups (RAAGs), which are a hybrid of free
groups and free abelian groups. I will then describe the more recent
construction of a contractible space on which the outer automorphism
group of a RAAG. acts, and discuss ways to exploit this space. This is
based on joint work with Bregman and Charney.
Venue: MCS0001
14:00 MCS2068 ProbIsao Suezedde (Warwick, UK): Stochastic calculus for EQFT
In Euclidean quantum field theory, we encounter challenge of rigorously defining some probabily measures for which we only have formal expressions. Approaches to this include stochastic quantization (i.e. constructing the measure as the invariant measure of some stochastic process) and lattice approach. I will introduce a third method, which is based on expressing the moments of the measure in term of some moments of Brownian bridges.
In this approach, mass term and magnetic potential are related respectively to integrals and stochastic integrals along the bridges. I will briefly talk about the case of the phi4 field, which is related to self-intersection measure of the bridges, and then about the case of Yang-Mills-Higgs field, which is related to the Amperean area of the bridges.
Venue: MCS2068
Mar 11 (Tue)
13:00 MCS2068 ASGMarkus Szymik (Sheffield University): Artin–Schreier quandles of involutions in absolute Galois groups
14:00 MCS2068 APDEGeorgios Domazakis (Durham University): Levy-driven Mean Field Games under displacement monotonicity
In this talk, we will discuss the existence and uniqueness of Nash equilibria for a Mean Field Game (MFG) system driven by a (possibly degenerate) mixed type of idiosyncratic noises, including both Brownian motion (local noise) and jump diffusion (nonlocal noise), within the framework of displacement monotonicity. The system is naturally formulated in terms of two key components: the forward-in-time nonlocal Fokker-Planck equation, which governs the evolution of the population distribution under the influence of both local and nonlocal noise, and the corresponding backward-in-time integrodifferential Hamilton-Jacobi-Bellman (HJB) equation, which characterizes the optimal control of individual agents. Assuming the associated Levy measure has finite second moments, we establish the existence of MFG equilibria using a classical Schauder fixed-point argument, without relying on ellipticity conditions or fractional regularity arguments. We then address the uniqueness of the solution by employing a stochastic control approach, described through the associated forward-backward stochastic differential equation (FBSDE) formulation. Our results extend the corresponding results on displacement monotone setting to the case of Levy--Ito jump diffusions. The talk is based on a joint work with Alpar R. Meszaros (Durham).
Venue: MCS2068
Mar 13 (Thu)
14:00 MCS2068 G&TMacarena Arenas (Cambridge): Taut smoothings and shortest geodesics
In this talk we will discuss the connection between
combinatorial properties of minimally self-intersecting curves on a
surface S and the geometric behaviour of geodesics on S when S is
endowed with a Riemannian metric. In particular, we will explain the
interplay between a smoothing, which is a type of surgery on a curve
that resolves a self-intersection, and k-systoles, which are shortest
geodesics having at least k self-intersections, and we will present some
results that partially elucidate this interplay.
Venue: MCS2068
Mar 14 (Fri)
13:00 MCS0001 HEPMPo-Shen Hsin (King's College London): TBA
Click on title to see abstract.
Back to Homepage
Click on series to expand.
Usual Venue: MCS3070
Contact: sabine.boegli@durham.ac.uk
Mar 11 14:00 Georgios Domazakis (Durham University): Levy-driven Mean Field Games under displacement monotonicity
In this talk, we will discuss the existence and uniqueness of Nash equilibria for a Mean Field Game (MFG) system driven by a (possibly degenerate) mixed type of idiosyncratic noises, including both Brownian motion (local noise) and jump diffusion (nonlocal noise), within the framework of displacement monotonicity. The system is naturally formulated in terms of two key components: the forward-in-time nonlocal Fokker-Planck equation, which governs the evolution of the population distribution under the influence of both local and nonlocal noise, and the corresponding backward-in-time integrodifferential Hamilton-Jacobi-Bellman (HJB) equation, which characterizes the optimal control of individual agents. Assuming the associated Levy measure has finite second moments, we establish the existence of MFG equilibria using a classical Schauder fixed-point argument, without relying on ellipticity conditions or fractional regularity arguments. We then address the uniqueness of the solution by employing a stochastic control approach, described through the associated forward-backward stochastic differential equation (FBSDE) formulation. Our results extend the corresponding results on displacement monotone setting to the case of Levy--Ito jump diffusions. The talk is based on a joint work with Alpar R. Meszaros (Durham).
Venue: MCS2068
Usual Venue: MCS2068
Contact: andrew.krause@durham.ac.uk
No upcoming seminars have been scheduled (not unusual outside term time).
Usual Venue: MCS2068
Contact: herbert.gangl@durham.ac.uk
Mar 11 13:00 Markus Szymik (Sheffield University): Artin–Schreier quandles of involutions in absolute Galois groups
Mar 18 13:00 Kalyani Kansal (Imperial College): Non-generic components of the Emerton-Gee stack for GL2
We will start by talking briefly about the history of the p-adic Langlands correspondence, and the form of the conjectures for categorical p-adic Langlands correspondence. We will introduce the Emerton-Gee stack (for GL2) which features as a key player in these conjectures. The reduced part of this stack can be viewed as parameterizing mod p Galois representations of the absolute Galois group of a finite extension of Qp. Restricting attention to unramified extensions of Qp, we will see precisely which of the irreducible components of the reduced Emerton-Gee stack are smooth or normal, and which have Gorenstein or Cohen-Macaulay normalizations, as well as determine their singular loci. We will see some consequences of these results for the conjectural categorical p-adic Langlands correspondence. This is based on joint work with Ben Savoie.
Venue: MCS2068
Usual Venue: OC218
Contact: mohamed.anber@durham.ac.uk
For more information, see HERE.
No upcoming seminars have been scheduled (not unusual outside term time).
Usual Venue: MCS3052
Contact: andrew.krause@durham.ac.uk
No upcoming seminars have been scheduled (not unusual outside term time).
Usual Venue: MCS2068
Contact: martin.p.kerin@durham.ac.uk
Mar 13 14:00 Macarena Arenas (Cambridge): Taut smoothings and shortest geodesics
In this talk we will discuss the connection between
combinatorial properties of minimally self-intersecting curves on a
surface S and the geometric behaviour of geodesics on S when S is
endowed with a Riemannian metric. In particular, we will explain the
interplay between a smoothing, which is a type of surgery on a curve
that resolves a self-intersection, and k-systoles, which are shortest
geodesics having at least k self-intersections, and we will present some
results that partially elucidate this interplay.
Venue: MCS2068
Mar 20 14:00 Fernando Galaz-García (Durham): TBA
May 01 14:00 Raphael Zentner (Durham): SL(2,C)-representations of 2-torsion homology spheres, and
applications to the Kauffman skein module
In recent joined work with Sudipta Ghosh and Steven Sivek we
prove that any rational homology 3-sphere whose first homology group is
2-torsion, and which is not a connected sum of RP^3s, admits irreducible
representations to SL(2,C) of its fundamental group. This has
applications to the question of torsion in the Kauffman skein module. We
will explain elements of the proof of our result, and how the
application to the skein module is derived.
Venue: MCS2068
Jun 12 14:00 Ilka Agricola (Marburg): TBD
Usual Venue: MCS0001
Contact: silvia.nagy@durham.ac.uk,enrico.andriolo@durham.ac.uk,tobias.p.hansen@durham.ac.uk
Mar 07 13:00 Max Elliot Huebner (Uppsala University): Non-Supersymmetric Orbifolds, Quivers and Chen-Ruan Orbifold Cohomology
We consider D3-brane probes of non-supersymmetric orbifolds and IIA on the same class of non-supersymmetric orbifolds. Both setups are characterized, in part, by quivers (which in the latter case relate for example to D0-brane probes) from which symmetries constraining the scale-dependence and tachyonic instabilities of the two systems, respectively, can be derived. We demonstrate that these considerations can be matched via a geometric analysis of the asymptotic boundary of the relevant orbifolds, in all cases, via considerations centered on Chen-Ruan orbifold cohomology.
Venue: MCS0001
Mar 14 13:00 Po-Shen Hsin (King's College London): TBA
Mar 21 13:00 Gabriele Travaglini (Queen Mary University of London): TBA
Usual Venue: MCS2068
Contact: kohei.suzuki@durham.ac.uk
Mar 10 14:00 Isao Suezedde (Warwick, UK): Stochastic calculus for EQFT
In Euclidean quantum field theory, we encounter challenge of rigorously defining some probabily measures for which we only have formal expressions. Approaches to this include stochastic quantization (i.e. constructing the measure as the invariant measure of some stochastic process) and lattice approach. I will introduce a third method, which is based on expressing the moments of the measure in term of some moments of Brownian bridges.
In this approach, mass term and magnetic potential are related respectively to integrals and stochastic integrals along the bridges. I will briefly talk about the case of the phi4 field, which is related to self-intersection measure of the bridges, and then about the case of Yang-Mills-Higgs field, which is related to the Amperean area of the bridges.
Venue: MCS2068
Usual Venue: MCS0001
Contact: raphael.zentner@durham.ac.uk
Mar 10 12:00 Karen Vogtmann (University of Warwick): Moduli spaces of tori, graphs and other RAAG-complexes
The classical symmetric space for the general linear group
is a contractible space on which the outer automorphism group Out(Z^n)
of a free abelian group (otherwise known as GL(n,Z)) acts with finite
stabilizers. Classical Outer space is a contractible space on which the
group Out(F_n) of outer automorphisms of a non-abelian free group acts
with finite stabilizers. These outer automorphism groups pop up in
diverse areas of mathematics, and studying these spaces has been a very
effective way to discover features of the groups. In this talk I will
first review these spaces, which are spaces of tori and graphs, then
introduce right-angled Artin groups (RAAGs), which are a hybrid of free
groups and free abelian groups. I will then describe the more recent
construction of a contractible space on which the outer automorphism
group of a RAAG. acts, and discuss ways to exploit this space. This is
based on joint work with Bregman and Charney.
Venue: MCS0001
Mar 17 12:00 Andras Juhasz (University of Oxford): TBA
