DEPARTMENT OF PHYSICS / HIP JOINT COLLOQUIA / SEMINARS 2025

    • Tuesday 18 November 2025 at 10:15 in A315 and using Zoom : Xin Li (Helsinki)
      Splitting of doubly and quadruply quantized vortices in holographic superfluids
      Abstract:       We investigate the splitting of vortices in holographic superfluids at finite temperatures, focusing on doubly and quadruply quantized vortices (with winding numbers 2 and 4). For doubly quantized vortices, we find that the growth rate of linear instabilities closely matches the characteristic time scale of the nonlinear splitting process, confirming the consistency between the two analyses. For quadruply quantized vortices, we analyze their linear stability and identify five unstable modes. As the temperature increases, three of them successively become the dominant mode, signaling two dynamical phase transitions and giving rise to three distinct splitting patterns. Two of these patterns have been observed experimentally, while the one at higher temperatures remains unreported, offering new theoretical guidance for future experiments.
    • Tuesday 25 November 2025 at 10:15 in A315 and using Zoom : Mikael Myllymäki (Helsinki)
      Precision Top Quark Mass Measurement at CMS Using the Profile Likelihood Method
      Abstract:       The most precise top quark mass measurements at the LHC are based on the kinematic reconstruction of the decay products from top and antitop quark production, especially in the decay channel with a single lepton and multiple jets. The most precise individual top quark mass measurement to date is determined from a profile likelihood fit using data recorded in 2016 with the CMS detector [1]. The profile likelihood method enables systematic uncertainties to be constrained, so that the total precision of the measurement can be improved by including more data, even when the measurement is almost exclusively limited by systematic uncertainties. In this talk, an extension of the CMS 2016 measurement is presented using data from 2016–2018, which is projected to significantly improve the total uncertainty of the measurement through the profile likelihood fit. [1] CMS Collaboration, Eur. Phys. J. C 83 (2023) 963, arXiv:2302.01967.
    • Tuesday 9 December 2025 at 10:15 in A315 and using Zoom : Tuomas Lappi (Jyväskylä)
      TBA
      Abstract:       TBA
    • Tuesday 22 January 2025 at 10:15 in A315 and using Zoom : René Meyer (Würzburg)
      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],
Tushar Gupta  (tushar.gupta at helsinki fi) [cosmo seminar]

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