The EU Underground Laboratories Workshop will be held at the Gran Sasso Laboratory, Italy, on April 28-29.

The Workshop aims to reinforce the network between EU Underground Laboratories in order to develop a strong synergy to face next generation experiments for rare events searches. The meeting will focus on reviewing the existing facilities and planned new ones for supporting research activities, strategy for collaboration and work load sharing, training and networking, interaction with the APPEC community.

After recalling the definition of a black hole and its basic properties (mass, angular momentum and area), the seminar will focus on links between black holes and gravitational waves. In particular black hole thermodynamics will be discussed in connection with gravitational wave emission, as well as the so-called black hole information paradox.

Contact kleydeapc.in2p3.fr for zoom meeting details. 

Gravitational wave (GW) standard sirens are well-established probes with which one can measure cosmological parameters, and are complementary to other probes like the cosmic microwave background or supernovae standard candles. I will focus on dark GW sirens, specifically binary black holes (BBHs) for which there is only GW data. Relying on the assumption of a source mass model for the BBH distribution, we consider four models that are representative of the BBH population observed so far.

I will discuss classes of hidden symmetries of gravity and their consequences for black holes and compact objects. 

Light dark matter candidates, such as axions and hidden photons, call for new ideas in direct detection. I discuss the recently proposed strategy of searching for e.g. axions using tunable cryogenic plasmas. The plasma haloscope enables resonant conversion by matching the axion mass to a plasma frequency, therefore converting axions to plasmons. Metamaterials are promising candidates, as the plasma frequency can be tuned. Besides axions, other dark matter candidates, such as hidden photons and scalars, can be successfully targeted with a plasma haloscope.