## DEPARTMENT OF PHYSICS / HIP JOINT COLLOQUIA / SEMINARS 2024

**Tuesday 19 November 2024 at 10:15 in A315 and using Zoom: Kuang Zhang (Helsinki)**

*Lattice and Finite-Element Simulations of Quench Dynamics and Defects of p-wave GL Effective Theory of Superfluid ^3He*

Ginzburg-Landau (GL) effective theory is a widely accepted theoretical frame of physical systems with phase transitions. For the case of superfluid liquid $^3$He, a p-wave GL theory is used. Because the p-wave nature of the Cooper pair of condensation, superfluid order parameter of liquid $^3$He is a tensor with 18-real components, and the equation of motion is a coupled non-linear system of 18 PDEs. This complicity obstructs researchers’ understanding of certain physics in a p-wave superlfuid, such as phase transition dynamics, topological defects and boundary effects etc. In this talk, I will present how we utilize the sophisticated HPC tools, which are developed by communities of lattice field theory and computational mathematics on hybrid CPU-GPU platforms, to overcome this difficulty. In particular, I will discuss lattice simulations of a first order transition between superfluid A- and B- phase under temperature quench, the applications of adaptive finite element method on resolving cosmology-like topological defects and spatial modulated configurations of order parameters in superfluid under nano-confinement.*Abstract:***Friday 29 November 2024 at 10:15 in Exactum C124: Dieter Haidt (Desy)**

*From Fermi to neutral currents and their impact*

The discovery of weak neutral currents in the Gargamelle experiment at CERN (1973) will be described and discussed in its historic context. Initially, the community was rather skeptical about the Gargamelle analysis, since at the same time a prominent American group had also presented an analysis denying the existence of weak neutral current. The discovery was the very first experimental verification, which gave substance to the theory of Weinberg published a few years before. In retrospect, the discovery was the beginning of electroweak physics and had an enormous impact in establishing the Standard Model of today.*Abstract:*

**Tuesday 10 December 2024 at 10:15 in A315 and using Zoom: Niccolò Forzano (Swansea)**

*Thermal evolution of dark matter symplectic glueballs*

We investigate a novel model for dark matter within a dark Yang–Mills theory governed by a symplectic gauge group, which presents similarities and differences from SU(N) models. We first determine the equation of state for this theory, focusing on temperatures near the phase transition and calculating the associated latent heat. We then explore the evolution of this dark matter model in the early universe, examining mechanisms for its potential indirect interactions with the visible sector, the gravitational wave spectrum it could generate, and the resulting relic abundances.*Abstract:*

**Tuesday 14 January 2025 at 10:15 in A315 and using Zoom: Michael Campbell (CERN)**

*Hybrid pixel detectors*

Hybrid pixel detectors were first developed for the LHC as they provide noise hit free imaging of particle collisions even at extremely high event rates. The same feature can be used to provide detection and imaging solutions in numerous other fields. The Medipix Collaborations, which are coordinated at CERN, have pioneered the spread of hybrid pixel detector technology to fields as far apart as space-based dosimetry, industrial X-ray analysis and inspection, homeland security, molecular biology, medical imaging and classroom experiments. This presentation will explain how hybrid pixel detectors work and cover how the Medipix and Timepix readout chips can provide unique imaging solutions to many different fields. The recent introduction of sub-ns timing at the pixel level combined with novel interconnect technologies permitting almost seamless coverage of large detection areas should further extend the reach of the technology.*Abstract:*

**Tuesday 21 January 2025 at 10:15 in A315 and using Zoom: Emidio Gabrielli (Trieste)**

*Entanglement at colliders*

*Abstract: TBA*

*Hopefully the up to 50 min + 10 min discussion long seminar/colloquium will be understandable to a wide audience.
Contacts: Keijo Kajantie (keijo kajantie at helsinki fi) [ HIP seminar],
Jaakko Annala (jaakko annala at helsinki fi) [cosmo seminar]*

New Nordic series of seminars over the web, link: https://sites.google.com/view/nordictheory/home

For more information, and to subscribe to email announcements, contact Oscar Henriksson (oscar henriksson at helsinki fi)

**Other related seminars**

*Friday 10-12 seminar series in D114:Astrophysics seminar*

Mathematical Physics Seminar and Workshop series Wed 14-16 in Exactum C123.

InstituteQ Events and Seminars

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