National Seminar Theoretical High Energy Physics

The National Seminar THEP will take place on Friday, November 15 th 2024.

  • DATE:

    Friday, 15th November 2024

    10:30 – 15:30 followed by drinks

     

  • SPEAKERS:

    Maximilian Attems (UvA/Nikhef)
    Koenraad Schalm (LEI)
    Luca Buoninfante (RU)
    Tomislav Prokopec (UU)

  • ABSTRACTS:

    Maximilian Attems (UvA/Nikhef) – Novel probes of the Quark-Gluon plasma
    Since the discovery of the primordial fluid, called the Quark-Gluon Plasma (QGP), in ultra-relativistic heavy-ion collisions the droplets of this almost perfect fluid are subject of intense research. After a review of what we have learned about the different stages of the hadronic collision I will emphasize two questions for the road ahead: How does a strongly coupled liquid the QGP emerge? How can we use jets to see the inner workings of the QGP?
    For the first question, we make use of the gauge/gravity duality to model the creation of a strongly coupled Quark-Gluon plasma in  the very early non-equilibrium stage with a non-trivial non-conformal equation of state. Regarding the second question, we propose a new experimental probe of a medium modified gluon to quark and anti-quark splitting function through the rate of collinear charm and anti-charm production in jets comparing  heavy-ion over proton-proton collisions.

    Koenraad Schalm (LEI) – Black holes, hydrodynamics and strange metal transport: successes and new discoveries.
    Abstract: to appear on the event page

    Luca Buoninfante (RU) – Remarks on ghost-like resonances
    Ghosts are fields whose kinetic operators and propagators have signs opposite to those of ordinary fields. They appear naturally in higher-derivative field theories, where they are typically responsible for improving the ultraviolet behaviour of loop diagrams through a faster fall-off of the propagator. In many ways, ghost particles behave very differently from ordinary particles, especially when quantum effects are taken into account. In this talk we analyse various aspects of ghost-like resonances: the resummation that leads to the dressed propagator, the poles locations, the analytic continuation into the second Riemann sheet and the spectral representations in both first and second sheets. In particular, we show that for real masses above the multiparticle threshold the ghost propagator has a pair of complex conjugate poles in the first sheet, unlike the case of an ordinary unstable resonance which has no pole in the first sheet but a complex conjugate pair in the second sheet. We discuss mathematical and physical implications of these features, also in relation to higher-derivative field theories and especially for Quadratic Gravity.

    Tomislav Prokopec (UU) – Semiclassical gravity and its limitations
    According to Semiclassical Gravity (SCG), matter is treated as quantum and gravity as classical. Since quantum gravitational effects are so weak, SCG has been successful and has many applications. For example, it provides a successful description of the dynamics of the early (and late) Universe, in which thermal plasma of the hot Big Bang, described by the one-loop quantum energy momentum tensor of the plasma, drives the Universe’s expansion.
    The central problem of contemporary cosmology is the creation and evolution of small gravitational perturbations on top of the homogeneous background. These perturbations encode most of the information we have about the primordial Universe, and their evolution is standardly treated as classical. In this talk I will argue that such a treatment may be inadequate and that — just as quantum matter properties are important for the background evolution — they may be important for the evolution of gravitational perturbations. I dub this nascent theory the Semiclassical Theory of Gravitational Perturbations (SCGP). Some preliminary results of SCGP will be discussed.

  • LOCATION:

    Nikhef colloquium room, Nikhef,  Science Park 105, Amsterdam

    https://go.nikhef.nl/colloquium

  • SCHEDULE:

    10:00 Coffee/tea
    10:30 Maximilian Attems (UvA/Nikhef)
    11:15 Koenraad Schalm (LEI) –Nikhef colloquium–
    12:15 Lunch
    14:00 Luca Buoninfante (RU)
    14:45 Tomislav Prokopec (UU)
    15:30 Borrel/drinks

  • LOCAL ORGANIZERS:

    For questions or suggestions, please contact one of the organizers:

    Melissa van Beekveld (NIKHEF)
    e-mail: mbeekvel@nikhef.nl

    Timothy Budd (RU)
    e-mail: T.Budd@science.ru.nl

    Subodh Patil (UL)
    e-mail: patil@lorentz.leidenuniv.nl