Zeit, Ort:

14:00 Uhr, Hybrid format: Bothe seminar room, Bothe building; login via zoom: https://zoom.us/j/92548552219?pwd=UCs5RFVlcGpzZWdpb0ZhYUUxUWdkZz09

Redner:

Lina Hedewig, Ludwig-Maximilians-Universität München

Titel:

Generation of Ar2+ from Ar+ and an Autofocus for Ion Microscopy

Zeit, Ort:

16:30 Uhr, Central seminar room (in-person plus zoom: https://zoom.us/j/93922533499?pwd=U2tscmt6RFJPenp3MzRBbzdNSTBqdz09 )

Redner:

Aqeel Ahmed (MPIK)

Titel:

Neutrino Portal Composite Dark Matter from a Light Hidden Sector

We present a class of models in which dark matter is composed of the composite states of a strongly coupled hidden sector. The hidden sector interacts with the standard model through the neutrino portal, allowing the relic abundance of dark matter to be set by annihilation into final states containing neutrinos. The coupling to the hidden sector also leads to the generation of neutrino masses through the inverse seesaw mechanism, with composite hidden sector states playing the role of the singlet neutrinos. We focus on the scenario in which the hidden sector is conformal in the ultraviolet, and the compositeness scale lies at or below the weak scale. We construct a holographic realization of this framework based on a five-dimensional warped geometry and study its phenomenology

Zeit, Ort:

11:15 Uhr, hybrid format: Otto Hahn lecture hall, library building or login via zoom: https://zoom.us/j/92548552219?pwd=UCs5RFVlcGpzZWdpb0ZhYUUxUWdkZz09, Meeting ID 925 4855 2219, Kenncode 505342

Redner:

Prof. Kiyoshi Ueda, Tohoku University, Japan

Titel:

Watching atoms and electrons in action with short wavelength free electron lasers

Abstract:The present talk will illustrate the current status of short-wavelength free-electron laser (FEL) experiments, focusing on characteristic properties of different facilities. The advent of hard x-ray FELs, such as SACLA in Japan, opened a route to extract the structure of a single nanoparticle [1] and its change upon the intense laser irradiation, which transforms the nanoparticle into a nanoplasma [2]. The first high repetition rate soft x-ray FEL, SASE3 of the European XFEL, combined with a Reaction Microscope/COLTRIMS, made the long-standing dream to watch atoms in action - initiated by photoexcitation of a molecule - a tangible reality, using the so-called core-level photoelectron diffraction technique for fixed-in-space molecules [3]. Generation of two-color attosecond pulse pairs at the LCLS in the USA finally opened the door to watching charge migration in a molecule, before the nuclear dynamics sets in, with an attosecond transient absorption technique based on the detection of resonant Auger electrons [4]. Generating phase-coherent multi-color pulses at FERMI, on the other hand, provided a novel approach to coherently control the electronic wave-packets [5] and to read out the photoionization phase [6]. These works were carried out by a wide range of international collaborations. I acknowledge all the collaborators in the authors list of [1-6] for fruitful collaborations. [1] A. Niozu et al. IUCrJ 7, 276 (2020); A. Niozu et al. PNAS 118, e2111747118 (2021).[2] T. Nishiyama et al. PRL 123, 123201 (2019); A. Niozu et al. PRX 11, 031046 (2021).[3] G. Kastire et al. PRX 10, 021052 (2020).[4] T. Barillot et al. PRX 11, 031048 (2021).[5] K. Prince et al. Nature Photonics 10, 176 (2016); D. Iablonskyi et al. PRL 119, 073203 (2017). [6] M. Di Fraia et al. PRL 123, 213904 (2019); D. You et al. PRX 10, 031070 (2020).