DEPARTMENT OF PHYSICS / HIP JOINT COLLOQUIA / SEMINARS 2025

  • Tuesday 14 January 2025 at 10:15 in A315 and using Zoom: Michael Campbell (CERN)
    Cancelled/Postponed
    Hybrid pixel detectors
    Abstract: 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.
  • Thursday 16 January 2025 at 10:15 in A315 and using Zoom: Michal Heller  (Gent)
    New looks at nonequilibrium phenomena at high and low energies
    Abstract: I will discuss recent insights into nonequilibrium dynamics at high and low energies originating from the interplay of slow and fast processes. These theoretical developments are motivated, on one hand, by ultrarelativistic nuclear collisions at RHIC and LHC and neutron star mergers, and on the other, by cold atom experiments.
  • Tuesday 21 January 2025 at 10:15 in A315 and using Zoom: Emidio Gabrielli (Trieste)
    Quantum Entanglement and Bell Inequality Violation at High Energies
    Abstract: I will present pioneering results demonstrating, for the first time, quantum entanglement and non-locality at high energies and in the presence of strong and weak interactions. Central to this discussion is Bell’s inequality relating the probabilities of different measurements on a given system. It is satisfied by local, deterministic theories and violated by quantum mechanics in the presence of entangled states. I will review the potential for detecting entanglement and testing Bell inequalities in collider experiments, focusing on diverse final states such as top-quark and tau-lepton pairs, Lambda baryons, massive gauge bosons, and vector mesons. Additionally, I will explore how entanglement offers a novel approach for constraining physics beyond the Standard Model, highlighting its most promising implications for future researches.
  • Tuesday 4 February 2025 at 10:15 in A315 and using Zoom: Laurids Jeppe (DESY)
    Searching for new scalars, pseudoscalars and top quark pair bound states at CMS
    Abstract: I will present a search for heavy pseudoscalar or scalar bosons decaying to a top quark pair ($t\bar{t}$) in final states with one or two charged leptons, using 138 fb$^{-1}$  of proton-proton collisions at $\sqrt{s} = 13$ TeV recorded by the CMS experiment. The invariant mass of the reconstructed $t\bar{t}$ system and variables sensitive to its spin state are used to discriminate against the standard model $t\bar{t}$ background and to infer spin quantum numbers. An excess of the data above the background prediction, as modeled using perturbative quantum chromodynamics (QCD) only, is observed with a significance of above five standard deviations. I will discuss three possible hypotheses to interpret the excess, which is located close to the $t\bar{t}$ production threshold: by production of an additional scalar or pseudoscalar boson, or by the existence of a color singlet pseudoscalar $t\bar{t}$ bound state, as predicted in a simplified model of nonrelativistic QCD. For the first two hypotheses, I will outline upper limits on the coupling of pseudoscalar or scalar bosons to top quarks in a mass range of 365-1000 GeV and relative widths of 0.5-25%. For the third scenario, I will present and discuss an extracted cross section of 7.1 pb with an uncertainty of 11%.
  • Tuesday 25 February 2025 at 10:15 in A315 and using Zoom: Samuli Autti (Lancaster)
    TBA
    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