Seminars WS 17/18

Tue 17.10.2017, 16.30 h (28B110)

Herbert Dreiner (Bonn)

R-Parity violation at the LHC

Supersymmetry is a well motivated extension of the SM. It comes in two variants: with and without R-parity. We motivate a "standard" model of R-parity violation and using CheckMATE determine how well it has been tested at the LHC and give corresponding mass bounds.


Tue 14.11.2017, 16.30 h (28B110)

Thierry Lasserre (CNRS)

Sterile Neutrinos & Dark Matter

Sterile Neutrinos & Dark Matter Abstract: Sterile neutrinos are hypothetical particles insensitive to the standard weak interaction. They could mix with the active neutrinos, however. Light (eV-scale) sterile neutrinos are intensively being searched by many experiments using neutrino beams, nuclear reactors, and radioactive sources. Moreover massive relic sterile neutrinos at the keV mass scale are well suited candidates to explain the Dark Matter in our Universe. We will review the current status and discuss the experimental perspectives for detecting Dark Matter sterile neutrinos. We will focus on the next generation of beta-decay and neutrino capture experiments.


Tue 21.11.2017, 16.30 h (28B110)

Aaron Vincent (Imperial College)

Illuminating the dark sector with astrophysical neutrinos

IceCube’s observation of high-energy extra extraterrestrial neutrinos has signalled the dawn of neutrino astronomy. These events carry energies upward of a PeV and are isotropically distributed in the sky, and thus far their origin remains unknown. However, these data contain valuable information in their energy, flavour composition and arrival directions. I will demonstrate how these observables can already be used to learn about new physics, and specifically discuss the case of dark matter-neutrino interactions, which have long been studied in the low-energy limit of cosmology.


Tue 12.12.2017, 16.30 h (28B110)

Jorg Horandel (Nijmegen)

Observing the low-frequency universe with LOFAR

The LOFAR radio telescope is observing the universe at frequencies from 10 to 240 MHz. This is a unique window not previously explored by other observatories. We will give an overview on the LOFAR key science projects, namely: Epoch of Reionisation, Deep extragalactic surveys, Transient sources, Solar science and space weather,  Cosmic magnetism, and Ultra high energy cosmic rays. Main focus of the talk will be recent results from the key science project Cosmic Rays. In the last years we achieved a breakthrough in the radio detection of extensive air showers and we have established the radio technique as standard tool to measure the properties of cosmic rays, such as their arrival direction, their energy, and their particle type/mass.


Tue 16.01.2018, 16.30 h (28B110)

Karsten Büsser (DESY)

The International Linear Collider - Status and Perspectives

The International Linear Collider ILC is a proposed e+ e- collider for energies of 250-500 GeV and upgrade
options towards 1 TeV. After the publication of the Technical Design Report in 2012, a proposal for its realisation has been put forward by the Japanese HEP community and a possible site for the ILC has been identified in northern Japan. The Japanese government is currently evaluating the ILC for a possible bid to host it as an international project. A decision is expected before the end of 2018.

In a first energy stage at 250 GeV, the ILC would serve as a Higgs factory that would allow for the measurement of the Higgs couplings with precisions of a few % and below. Later energy upgrades to 350-500 GeV and beyond would make precision measurements as the mass and couplings of the top quark as well as measurement of the Higgs self coupling possible.

I will discuss the physics motivation for the ILC and challenges in the design of the accelerator and the detectors as well as the status of the international discussions about a possible realisation in Japan.


Tue 23.01.2018, 16.30 h (28B110)

Walter Winter (DESY Zeuthen)

Fundamental physics tests with neutrinos traveling over cosmological distances

I briefly review the recent results from the IceCube experiment and introduce the particle astrophysics of neutrino sources. Then I focus on two applications for fundamental physics tests: physics beyond the Standard Model changing the neutrino flavor composition at detection, and propagation effects over cosmological distances - at the example of neutrino lifetime.


Tue 30.01.2018, 16.30 h (28B110)

Philipp Mertsch (RWTH Aachen)

Three elephants in the gamma-ray sky

There are three elephants in the gamma-ray sky, extended diffuse emission that is just too big to be ignored: the Galactic centre excess, the Fermi bubbles and Loop I. Yet, to varying degrees, these structures are often times glossed over, if not ignored altogether. Lately, observational evidence and theoretical arguments have connected the Galactic centre excess with the Fermi bubbles and the Fermi bubbles with Loop I. This goes to show that neither can be interpreted separately and implies the need for a global picture.

We will work our way from the inside out, starting with the Galactic centre excess and its importance for dark matter indirect searches. Moving on to the Fermi bubbles, I will explain our recent numerical model that for the first time allows reproducing the observational data from radio waves to gamma-rays with confidence. Finally, I will discuss the large, prominent radio structure Loop I, our ignorance of its distance and how it can contaminate the CMB.