Wed, 22 Oct 2025

13:00 - 14:00
Quillen Room N3.12

Superconformal Field Theory on Threebranes at a Calabi-Yau Singularity

Tabea Sieper
Abstract

Just as parallel threebranes on a smooth manifold are related to string theory on AdS_5 \times S^5, parallel threebranes near a conical singularity are related to string theory on AdS_5 \times X_5 for a suitable X_5. For the example of the conifold singularity Klebanov and Witten conjectured that a string theory on AdS_5 \times X^5 can be described by a certain \mathcal{N}=1 supersymmetric gauge theory. Based primarily on their work (arXiv:hep-th/9807080), I describe the gravitational setup of this correspondence as well as their construction of the field theory, allowing for various checks of the duality.

Junior Strings is a seminar series where DPhil students present topics of common interest that do not necessarily overlap with their own research area. This is primarily aimed at PhD students and post-docs but everyone is welcome.


 

Mon, 03 Nov 2025
16:00
C3

TBC

Julie Tavernier
(University of Bath)
Abstract

TBC

Mon, 27 Oct 2025
16:00
C3

On the distribution of very short character sums

Paweł Nosal
(University of Warwick)
Abstract
In their paper concerning quadratic residues Davenport and Erdős show that normalized sums of Legendre symbols $(\tfrac{n}{p})$ of suitable length $H(p) = p^{o(1)}$, with uniformly random starting point $X \in [0,...,p-1]$ obey the Central Limit Theorem, as the size of prime conductor goes to infinity.  
 
Recently, Basak, Nath and Zaharescu proved that the CLT still holds, if we pick $X$ uniformly at random from $[0,...,(\log p)^A], A>1$ , set $H(p) = (\log p)^{o(1)}$ and take the limit along full density subset of primes.  
 
In this talk, I will present a modification of their approach, inspired by the work of Harper on short character sums over moving intervals. This allows us to obtain the CLT of this type with $X$ uniformly random from $[0,...,g(p)]$ with practically arbitrary $g(p) \ll p^{\epsilon}$ for all $\epsilon >0$.
Mon, 20 Oct 2025
16:00
C3

An application of Goursat’s Lemma to the irreducibility of Galois representations

Zachary Feng
(University of Oxford)
Abstract
Goursat’s Lemma is an elementary, but perhaps niche, result in group theory classifying subdirect products of the product of two groups. In this talk, I will review what this lemma says, and describe how it can be used to deduce the irreducibility of Galois representations.

 
Bridging a gap: a heavy elastica between point supports
 Curtis, G Griffiths, I Vella, D International Journal of Solids and Structures volume 326 (29 Oct 2025) doi:10.1016/j.ijsolstr.2025.113702
The informal diplomacies of Oswald Veblen
 Hollings, C Kennedy, S Luciano, E Bulletin of the American Mathematical Society volume 63 issue 3 491-529 (29 Apr 2026) doi:10.1090/bull/1886
Thu, 06 Nov 2025

16:00 - 17:00
L5

The value of information flows in the stock market - joint with Hai Duong

Prof. Bart Taub
(University of Glasgow)
Abstract
Stock market traders who trade because of information they possess reveal that information to the rest of the market in the process of bidding: if the information is positive they bid up the price, and if it is negative they lower it.   New information constantly develops and is brought to the market in this way, and because it influences prices, it ultimately influences the allocation of investments by firms.  
 
Using a new approach, we estimate the flow of this information and the price of that information (different from the stock price), and thus its value, for each stock, and then sum up this value across all stocks, obtaining an estimate of the total value of the dynamic flow of information in the stock market as a whole. This requires digesting the records of millions of stock orders (including cancelled orders, not just executed trades) to construct the dynamic limit order book and estimate the information flow and value from its structure.  
 
Our results support the notion that the cross-correlation of price impact across stocks is consistent with the CAPM: there is a single systematic component of price impact, and this is driven by the volatility of the systematic component of the stock market. This result suggests that by separating the underlying information into two components, systematic and idiosyncratic, informed traders distinguish between productive assets that have a systematic impact on the economy and those that can be diversified.  


 

Song of the Week: Miles Davis - Générique

This track is from the soundtrack to the Louis Malle 1958 film Ascenseur pour l'échafaud. Apparently Davis only gave the musicians a few rudimentary harmonic sequences, and, once the plot was explained, the band improvised without any precomposed theme, while edited loops of the relevant film sequences were projected in the background.

Makes you want to go to the movies.

QSHS: an axion dark matter resonant search apparatus
 Alsulami, A Bailey, I Carosi, G Chapman, G Chakraborty, B Daw, E Du, N Durham, S Esmenda, J Gallop, J Gamble, T Godfrey, T Gregori, G Halliday, J Hao, L Hardy, E Laird, E Leek, P March-Russell, J Meeson, P Mostyn, C Pashkin, Y Peatain, S Perry, M Piscitelli, M Reig, M Sarkar, S Sokolov, A Tan, B Withington, S New Journal of Physics volume 27 issue 10 (06 Oct 2025) doi:10.1088/1367-2630/ae0756
Nonequilibrium physics of brain dynamics
 Nartallo-Kaluarachchi, R Kringelbach, M Deco, G Lambiotte, R Goriely, A Physics Reports volume 1152 1-43 (24 Oct 2025) doi:10.1016/j.physrep.2025.10.003
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