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Würzburg Dark Matter Workshop

Würzburg Dark Matter Workshop (11.05.2023 – 12.05.2023)

From the 11.05.2023–12.05.2023, the Würzburg Dark Matter Workshop will take place. We will elaborate from different perspectives, how to possibly detect dark matter, be it in the form of WIMPs, light dark matter particles or primordial black holes, directly and indirectly. On the first day, there will be contributed talks in the afternoon. On the second day, there will be interactive Q&A sessions.

Online participation is possible via this zoom link: https://ucsd.zoom.us/j/93285541497 
The password is the all capitalised acronym in the previous paragraph without the s.



13:55–14:00 Welcome
Thomas Siegert (Uni Würzburg)

Direct Searches for Dark Matter – a XENON Perspective
Uwe Oberlack (Uni Mainz)


Indirect Dark Matter Searches with Fermi-LAT (PDF)
Chris Karwin (NASA/GSFC)


Indirect Direction of TeV-Scale Dark Matter Candidates with MAGIC (PDF)
Karl Mannheim (Uni Würzburg)


Recent Results on MeV Dark Matter Candidates (PDF)
Thomas Siegert (Uni Würzburg)

15:55–16:15 Coffee break

Light particle dark matter and MeV gamma-ray observation (PDF)
Shigeki Matsumoto (IPMU)



09:30–10:00 New hints on ALPs from GRB 221009A and prospects for COSI (PDF)
Fabrizio Tavecchio (INAF, online)
10:00–10:30 Indirect Search for Scotogenic WIMP Dark Matter (PDF)
Laura Eisenberger (Uni Würzburg, online)
10:30–11:00 Thermal real scalar triplet dark matter (PDF)
Yu Watanabe (IPMU)
11:00–11:15 Coffee break
11:15–12:00 Q&A Session I:
What did you always want to know about dark matter but never did to ask?
12:00–12:45 Q&A Session II:
How can I detect my dark matter model with COSI?
12:45–14:00 Lunch break
14:00–17:00 Wrap up of COSI and Dark Matter workshop (internal)



Uwe Oberlack (Uni Mainz):
Direct Searches for Dark Matter – a XENON Perspective

A wealth of astrophysical and cosmological evidence indicates the presence of non-baryonic dark matter (DM), which outweighs “regular” baryonic matter by at least a factor of five in the universe today. Despite having been first observed about 90 years ago, we have yet to unravel its physical nature. After an introduction to the topic, we will focus on one of the three main directions of searching for DM: directly, indirectly, and at accelerator experiments. The XENON project was initiated two decades ago and has been pushing the limits of direct detection with the novel technique of dual-phase liquid xenon time projection chambers (LXeTPC). XENONnT is the most recent, fourth generation of DM searches at the underground laboratory LNGS in Italy. We will present the current status and future directions, aiming (not only) at fully exploring the accessible parameter space for Weakly Interacting Massive Particles (WIMPs) down to the “neutrino fog”.


Karl Mannheim (Uni Würzburg):
Indirect Direction of TeV-Scale Dark Matter Candidates with MAGIC 

The indirect search for dark matter annihilation (DMA) with MAGIC startet in 2010 following a multi-prong strategy centered on clusters of galaxies, dwarf spheroidal galaxies, and the Galactic Center using high zenith-angle observations.  Combined with the results obtained with other IACTs and Fermi-LAT,  the currently achieved DMA limits for quasi-continuum and line emission due to the most important production channels of photons already cut deep into the viable SUSY parameter space for neutralino-like WIMP dark matter.  Theoretical predictions of the DMA-induced extragalactic background flux and of the supergalactic anisotropy  limit boost factors arising from the DMA subhalo clumping.  With the LST-array on La Palma approaching its completion, prospects for indirect DMA searches at the EW symmetry-breaking scale are bright.  Complementary observations of the synchrotron (radio) and IC emission (COSI) associated with charged leptons will allow to combat the complex astrophysical background and to improve the significance of the putative faint signal.


Chris Karwin (NASA/GSFC):
Indirect Dark Matter Searches with Fermi-LAT
With over 14 years of data collection, many dark matter (DM) searches have been performed with Fermi-LAT. Notably, a systematic excess of gamma rays has been detected coming from the Galactic Center (GC) region, and the current leading explanations include mis-modeling of the Galactic diffuse emission along the line of sight, emission from a sub-threshold source population such as millisecond pulsars, and/or WIMP DM annihilation. However, no complementary signal has yet been detected from a combined analysis of the Milky Way dwarf spheroidal satellite galaxies, and numerous studies have placed upper limits on the DM annihilation cross section. These upper limits remain one of the most robust and stringent constraints from indirect DM searches and, specifically, they are crucial for DM interpretations of the GC excess. Other complementary studies have provided competitive and independent upper limits as well, including those obtained from dwarf irregular galaxies, the Large and Small Magellanic Clouds, Galactic DM subhalos, the Milky Way halo, M31, galaxy clusters, the extragalactic gamma-ray background, and DM signals towards the Sun. Limits have also been placed on models of axion-like particles (ALPs), in this case looking for ALP-induced spectral distortions in LAT data. In this talk I will give a broad overview of these past results and also discuss future prospects for indirect DM searches with the LAT.


Laura Eisenberger (Uni Würzburg):
Indirect Search for Scotogenic WIMP Dark Matter

Weakly interacting massive particles (WIMPs) are one of the most promising candidates for dark matter. They are predicted for example by scotogenic models which implement an additional Z2 symmetry under which all Standard Model particles are even while new particles, among them a stable dark matter candidate, are odd. In our study, we use a scotogenic model (T1-2-A′) which can explain neutrino masses and the muon anomalous magnetic moment while fulfilling the current limits for charged lepton flavour violating processes simultaneously. In addition, it also incorporates a new WIMP dark matter type (m=1.1 TeV) consistent with limits from direct dark matter detection experiments. We focus on the indirect search for this promising dark matter candidate via the detection of annihilation signals. For this, we predict multiwavelength spectral energy distributions (SEDs) reaching from very-high-energy photons from pion decay to secondary Inverse Compton and synchrotron emission. The results are compared to observational limits.


Thomas Siegert (Uni Würzburg):
Recent Results on MeV Dark Matter Candidates

The spectrometer SPI onboard the INTEGRAL satellite is the currently most sensitive instrument for the indirect search of light dark matter, be it in the form of decaying or annihilating particles, axions, or primordial black holes. Thanks to its high resolution, also the search for gamma-ray lines from decaying/annihilating dark matter in the MeV band is possible in addition to the search for the expected final state radiation of standard model particle products. Furthermore, the MeV band is ideal to search for secondary and tertiary interactions of dark matter decay/annihilation products, such as electrons and positrons, as they will interact with the Cosmic Microwave Background and the interstellar radiation field via Inverse Compton scattering, and eventually annihilate to gamma-rays themselves, showing a characteristic 511 keV line. In this talk, I will summarise the latest results on the indirect search of light dark matter particles.


Shigeki Matsumoto (IPMU):
Light particle dark matter and MeV gamma-ray observation
MeV gamma-ray observations, such as the COSI project, are now being developed. These enable us to search for cosmic dark matter candidates that must be charted experimentally/observationally. We will focus on particle dark matter candidates in this talk, mainly the light thermal dark matter, a natural extension of WIMP whose mass is lighter enough than the electroweak scale. Such a candidate is usually constrained by CMB observations seriously and requests some discussions to be a target at the observations. We propose a framework to discuss the dark matter at future MeV gamma-ray observations and demonstrate, using some concrete examples, that it works.


Fabrizio Tavecchio (INAF):
New hints on ALPs from GRB 221009A and prospects for COSI
The detection by LHAASO up to 18 TeV of the gamma ray burst GRB 221009A at redshift z = 0.151 challenges standard physics because of the strong absorption due to the EBL for photons with energies above 10 TeV. Mixing of photons with axion-like particles (ALPs) can naturally explain the detection, providing a strong hint at ALP existence. I will briefly discuss the prospects for COSI, focusing in particular to the polarization features possibly detectable in the MeV band.


Yu Watanabe (IPMU):
Thermal real scalar triplet dark matter
Real scalar triplet dark matter, which is known to be an attractive candidate for a thermal WIMP, is comprehensively studied paying particular attention to the Sommerfeld effect on the dark matter annihilation caused by the weak interaction and the other interaction between the dark matter and the Higgs boson. We find a parameter region that includes the so-called ‘WIMP-Miracle’ one is still surviving, i.e. it respects all constraints imposed by dark matter searches at collider experiments, underground experiments (direct detection) and astrophysical observations (indirect detection). The region is also found to be efficiently searched for by various near future experiments. In particular, the XENONnT experiment will cover almost the entire parameter region.

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