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Fri 19 Apr 16:00: Flavor Hierarchies from Minimal U(2) Symmetries

School of Physical Sciences - Wed, 17/04/2024 - 14:02

Flavor Hierarchies from Minimal U(2) Symmetries

We explore the possibility that the distinct patterns observed in fermion masses and mixings may be due to a minimally-broken U(2) flavor symmetry giving rise to an accidental U(2)^5 symmetry in the Yukawa couplings of the charged fermions. In model-independent analysis we find that the selection rules of the U(2) symmetry enhances the importance of charge lepton flavor violation as a probe for new physics. I will also present an economical realization of the framework with a renormalizable model, which links all flavor hierarchies to a single hierarchy of scales at high energies. The model has a rich phenomenology with promising signatures, especially in the context of K and B meson physics.

Speaker: Anders Eller Thomsen (Bern U.)
Friday 19 April 2024, 16:00-17:00
Venue: MR19 (Potter Room, Pavilion B), CMS.
Series: HEP phenomenology joint Cavendish-DAMTP seminar; organiser: Nico Gubernari.

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Wed 24 Apr 14:15: Porphyrins In Discrete Metal-Mediated Assemblies

School of Physical Sciences - Wed, 17/04/2024 - 13:35

Porphyrins In Discrete Metal-Mediated Assemblies

Given the fundamental role of (metallo)porphyrins in various natural processes, integration of these functional units into artificial ensembles is an enduring task for supramolecular chemists.1a,b In this wide context, the metal-mediated assembling approach has afforded a variety of spectacular 3D discrete arrays of porphyrins with new functions, ranging from molecular recognition to (photo)catalysis.1c Over the years we also have employed (metallo)porphyrins and coordination compounds for the obtainment of discrete multi-component systems, mostly for artificial photosynthesis purposes.2 More recently, we expanded our interests towards two main directions: i. preparation and photophysical investigation of metalloporphyrins as photosensitizers/catalysts for H2 generation3a or as photoactive units to model Proton Coupled Electron Transfer processes;3b,c ii. possible strategies for the obtainment of heretoleptic porphyrin metallacycles.4 An excursion on the most fascinating past and recent examples will be presented.

Speaker: Professor Elisabetta Iengo
Wednesday 24 April 2024, 14:15-15:15
Venue: Dept. of Chemistry, Pfizer Lecture Theater.
Series: Materials Chemistry Research Interest Group; organiser: Sharon Connor.

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Wed 21 Aug 16:00: Kirk Public Lecture: Title TBC SSD - Stochastic systems for anomalous diffusion

School of Physical Sciences - Wed, 17/04/2024 - 12:30

Kirk Public Lecture: Title TBC

SSD - Stochastic systems for anomalous diffusion

Speaker: Ruth Williams (University of California, San Diego)
Wednesday 21 August 2024, 16:00-17:00
Venue: Seminar Room 1, Newton Institute.
Series: Isaac Newton Institute Seminar Series; organiser: nobody.

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Mon 12 Aug 16:00: Rothschild Public Lecture: On Archimedes' Principle SSD - Stochastic systems for anomalous diffusion

School of Physical Sciences - Wed, 17/04/2024 - 12:30

Rothschild Public Lecture: On Archimedes' Principle

Archimedes’ principle says that the upward buoyant force that is exerted on a body submerged in a fluid is equal to the weight of the displaced fluid. There is no mathematical literature on Archimedes’ principle exceptfor two articles co-authored by the speaker. This is because the principle can be easily derived from standard macroscopic laws of physics regarding pressure. I will show how the principle can be derivedfrom Newtonian mechanics applied to “ideal gas” consisting of point particles. Besides the derivation from a “lower level” theory, the main novelty is that the macroscopic floating object is allowed to move, unlike in the traditional proof. The talk is based on joint research with Jacek Małecki

SSD - Stochastic systems for anomalous diffusion

Speaker: Krzysztof Burdzy (University of Washington)
Monday 12 August 2024, 16:00-17:00
Venue: Seminar Room 1, Newton Institute.
Series: Isaac Newton Institute Seminar Series; organiser: nobody.

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Thu 06 Jun 16:00: Kirk Public Lecture: Evading Newton’s third law to set patterns in motion ADI - Anti-diffusive dynamics: from sub-cellular to astrophysical scales

School of Physical Sciences - Wed, 17/04/2024 - 12:30

Kirk Public Lecture: Evading Newton’s third law to set patterns in motion

Newton’s third law establishes that pair interactions are reciprocal: for every action, there is an equal and opposite reaction. In some nonequilibrium multicomponent systems, however, interactions among different elements seem to evade this law. This occurs for instance when mesoscale forces are mediated by a nonequilibrium environment and is common in the living world, from molecular interactions between proteins to antagonistic interactions between predators and their prey and social forces. This nonreciprocity breaks time-reversal symmetry, resulting in the emergence of traveling and oscillating patterns. After reviewing familiar theoretical approaches to phase separation of two immiscible fluids, such as oil and water, I will introduce a minimal model for the emergence of both spatial and temporal order observed in a broad class of nonequilibrium settings, from chemical reactions in living cells to active cytoskeletal gels. These systems can be described in terms of two conserved concentration fields that ``chase’’ each through antagonistic cross-diffusivities. The resulting nonreciprocal dynamics yields a rich variety of traveling and oscillating patterns, with many features that can be analyzed analytically. This model provides a generic description for the transition from stationary to self-organized dynamical patterns and identifies a new class of pattern formation.

ADI - Anti-diffusive dynamics: from sub-cellular to astrophysical scales

Speaker: M Cristina Marchetti (University of California, Santa Barbara)
Thursday 06 June 2024, 16:00-17:00
Venue: Seminar Room 1, Newton Institute.
Series: Isaac Newton Institute Seminar Series; organiser: nobody.

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Wed 05 Jun 16:00: Rothschild Public Lecture: Inertia, Turbulence and the Concentration Field in Active Fluids ADI - Anti-diffusive dynamics: from sub-cellular to astrophysical scales

School of Physical Sciences - Wed, 17/04/2024 - 12:30

Rothschild Public Lecture: Inertia, Turbulence and the Concentration Field in Active Fluids

The spectacular phenomena displayed by fluids of self-driven particles arise through the interplay of broken time-reversal symmetry with conservation laws of matter and total momentum. I will open with the transition from order to active turbulence, the end-state of the instability of aligned states of orientable motile particles, with an inertial rather than a viscous perspective. I will discuss two simplifying limits – a one-component active fluid, and a densely packed suspension – in which the active-particle concentration does not appear explicitly. I will then turn to the interplay of hydrodynamic flow and particle number in varied settings: an obstacle in a dilute suspension, as well as phenomena in denser systems. At each stage I will highlight fundamental theoretical issues.

ADI - Anti-diffusive dynamics: from sub-cellular to astrophysical scales

Speaker: Sriram Ramaswamy (Indian Institute of Science)
Wednesday 05 June 2024, 16:00-17:00
Venue: Seminar Room 1, Newton Institute.
Series: Isaac Newton Institute Seminar Series; organiser: nobody.

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Tue 30 Apr 14:00: Information Measures in Selected Learning Problems Note unusual day of the week and location

School of Physical Sciences - Wed, 17/04/2024 - 10:17

Information Measures in Selected Learning Problems

Abstract: Shannon’s information measures played a fundamental role in the study of information storage and communication. In recent years, however, such measures also emerged naturally in the study of machine learning theory and algorithms. In this presentation, we present new results on three such problems: 1) the study of multi-armed bandits when there exists heterogeneity in the reward variances, 2) policy optimization for the Markov decision process with multiple reward functions, and 3) the study of machine learning generalization error bounds. It is shown that information measures can also naturally capture effects in learning theory and algorithms that are not directly related to information storage and communications, and we expect them to play pivotal roles in the study of machine learning algorithms in the future.

Bio: Dr. Chao Tian received the B.E. degree in Electronic Engineering from Tsinghua University, Beijing, China, and the M.S. and Ph. D. degrees in Electrical and Computer Engineering from Cornell University, Ithaca, NY. Dr. Tian was a postdoctoral researcher at Ecole Polytechnique Federale de Lausanne (EPFL), then a member of technical staff—research at AT&T Labs—Research, an Associate Professor in the Department of Electrical Engineering and Computer Science at the University of Tennessee Knoxville, and is now an Associate Professor in the Department of Electrical and Computer Engineering at Texas A&M University. His authored and co-authored papers received the 2014 IEEE Data Storage Best Paper Award, the 2017 IEEE Jack Keil Wolf ISIT Student Paper Award, and the 2020-2021 IEEE Data Storage Best Student Paper Award. He was an Associate Editor for the IEEE Signal Processing Letters 2012-2014, an Editor for the IEEE Transactions on Communications 2016-2021, and an Associate Editor for the IEEE Transactions on Information Theory 2021-2023. He is a general co-chair of the 2024 IEEE Information Theory Workshop.

Note unusual day of the week and location

Speaker: Prof Chao Tian, Texas A&M University
Tuesday 30 April 2024, 14:00-15:00
Venue: MR3, CMS Pavilion A.
Series: Information Theory Seminar; organiser: Dr Varun Jog.

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