DEPARTMENT OF PHYSICS / HIP JOINT COLLOQUIA / SEMINARS 2026

• • Tuesday 11 August 2026 at 10:15 in A315 and using Zoom: Christophe Royon (CMS)
    From the odderon discovery, the observation of saturation of the gluon density,  to the search for axion-like particles at the Large Hadron Collider
    Abstract: After describing elastic interactions and the discovery of the odderon, by the TOTEM and D0 Collaborations, we will discuss a new regime where the gluon density in the proton or Pb can be very large which leads to new equations in Quantum Chromodynamics. We will also present the latest expectations on beyond standard model physics and especially the production of axion-like particles using intact protons after the collision. We will finish by describing briefly the Low Gain Avalanche Detectors and their applications in medicine for cancer treatment and with NASA to measure cosmic rays.
  • Tuesday 18 August 2026 at 10:15 in A315 and using Zoom: Andrea Malara (Université Libre de Bruxelles)
    Probing the Invisible: Higgs Boson Decays and Dark Matter
    Abstract: Invisible particles at the LHC can reveal themselves through an imbalance in transverse momentum, accompanied by visible objects recoiling against them. Such signatures provide powerful probes of dark matter and of nonstandard invisible decays of the Higgs boson. This seminar will review the CMS searches for invisible Higgs-boson decays using the full Run 2 data set, highlighting the complementary production channels, the principal experimental challenges, and the methods used to constrain the dominant Standard Model backgrounds. I will then present the new CMS Run 3 monojet result, based on 62 fb^-1 of proton–proton collision data collected in 2022–2023 at sqrt(s)=13.6 TeV. The search targets events with energetic jets and large missing transverse momentum. Its results are interpreted in terms of invisible Higgs decays, simplified dark-matter models, and models with large extra spatial dimensions.
  • Monday 24 August 2026 at 14:15 in A315 and using Zoom: Robert D. Pisarski (Brookhaven); Note unusual time!
    Syncreticity with fractional ‘t Hooft determinants in the chiral phase transition
    Abstract: The order of the chiral phase transition at nonzero temperature, T, continues to puzzle. I conjecture that for massless quarks, the chiral phase transition at T_χ is syncretic: terms which break the axial U(1)_A symmetry are fractional powers of ‘t Hooft determinants in the broken phase (for N_c colors, an integer times 1/N_c) but involve only integral powers of ‘t Hooft determinants in the chirally symmetric phase; terms symmetric under U(1)_A remain of the same form for all T and µ. For three flavors, N_f =3, the chiral transition is predicted to be weakly first order, and could well be very weakly. For N_f ≥ 1, the chiral transition is generically “beyond Landau”, as it is for T ≠ 0 and imaginary µ. This can be tested, now, for lattice QCD with 2+1 flavors.

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