[ NIKHEF theory group ]


To meet, discuss, collaborate, generate ideas, share expertise, in the context of the FOM programme "Higgs as Probe and Portal"

We hope to see you here!

Agenda 19 May 2017

Time: 10.00 - 17.00
  • 10.30 - 11.00, H320:

    Thomas Konstandin (Desy)
    The effective action as a tool in particle physics and cosmology

    Abstract: Several notable applications of the effective action exist in particle physics and cosmology. First, I will provide an extensive introduction to the basic concepts of effective actions and spontaneous symmetry breaking. Next, I will focus on some topics that have been discussed in the literature recently. These are the resummation of the infrared contributions, issues concerning the gauge-dependence of the effective action and the interplay of these two effects.

  • 11.00 - 12.00, H331 (Nikhef colloquium, not part of HPP meeting):

    Patrick Koppenburg
    On pentaquark particles and their discovery at LHCb

    Abstract: It has now been over 50 years since the inception of the quark model. The original papers by Gell-Mann and Zweig included the description of the now well known three-quark baryons and quark-antiquark mesons. They also included the possibility of "exotic" hadrons, such as mesons containing two quarks and two antiquarks (tetraquarks), or four quarks and an antiquark (pentaquarks). There is no clear reason why such exotic combinations of quarks should not exist. Indeed, in recent years strong tetraquark candidates have been discovered. However, until recently the observation of any lasting pentaquark candidates had eluded all searches. Using the LHCb Run 1 dataset, two J/ψp resonances consistent with pentaquark states have been observed in Λb→J/ψpK- decays and recently confirmed in Λb0 → J/ψpπ- decays. We will briefly introduce the LHCb experiment, present the status of searches for pentaquarks and describe the amplitude analysis that led to the observation of the new states. Their nature is still disputed. Possible future studies that could determine their nature will be presented.

  • 14.20 - 14.50, H331

    Bogumila Swiezewska (Utrecht)
    Radiative symmetry breaking induced by a Higgs portal

    Abstract: In this talk the issue and pattern of radiative symmetry breaking within models where the Standard Model is coupled to new physics (extra scalars and possibly extra gauge groups) through a Higgs portal will be discussed. With radiative symmetry breaking all scales present in a theory are generated dynamically thus curing the hierarchy problem of the SM. I will provide a model in which radiative symmetry breaking occurs, giving the correct value of the mass of the Higgs boson and the potential is stable up to the Planck scale. I will discuss different approximations and subtleties involved when working with an effective potential which is a function of multiple scalar fields.

  • 15.00 - 16.00, H331

    Special Seminar:

    Martin Beneke (TUM)
    TeV scale MSSM Dark Matter and the electroweak Sommerfeld effect

    Abstract: For heavy MSSM dark matter with a dominant triplet (wino) component, resummation of large quantum corrections due to the electroweak force (the "Sommerfeld" effect) is imperative for a reliable calculation of the annihilation cross section. In this talk I first discuss how this is done within the non-relativistic effective field theory of the full MSSM. It is then investigated whether dominantly wino dark matter with the correct thermally produced relic density remains viable in the light of strong constraints from the non-observation of cosmic ray and terrestrial dark-matter on nuclei scattering signals.

  • 16.00 "Physics Cafe". This is an informal Nikhef event. It is not part of HPP, but we are invited to join. There are two 10-minute science presentations and drinks.


    - Kasper van Dam (HiSPARC)

    HiSPARC: where outreach meets science. How we use many low-budget detectors to measure cosmic air showers.

    - Juan Rojo (Theoretical Physics)

    Does the God Particle talk to itself? Unraveling the Higgs self-interactions at the LHC