Conveners
Cosmology and Particle Physics: parallel session 1
- Oliver Hahn
Cosmology and Particle Physics: parallel session 3
- Michal Malinský (IPNP, Charles University, Prague)
Cosmology and Particle Physics: parallel session 4
- Julien Lavalle (LUPM (CNRS / Univ. Montpellier))
The Simons Observatory (SO) is a cosmic microwave background (CMB) survey experiment located in the Atacama Desert in Chile at an elevation of 5200 meters, consisting of an array of three 0.42-meter small aperture telescopes (SATs) and one 6-meter large aperture telescope (LAT). SO will make accurate measurements of the CMB temperature and polarization spanning six frequency bands ranging from...
Although one of the two namesakes of the LCDM cosmological model, the hypothesis of cold dark matter existence still chiefly relies on its gravitational effects, whilst both direct and indirect detection via non-gravitational signatures have not yet been achieved.
Weakly interacting massive particles (WIMP) are a candidate cold relic with a mass of 1-1000 GeV: they might then annihilate or...
Dark matter energy injection in the early universe modifies both the ionization history and the temperature of the intergalactic medium.
In this work, we improve the CMB bounds on sub-keV dark matter and extend previous bounds from Lyman-$\alpha$ observations to the same mass range, resulting in new and competitive constraints on axion-like particles (ALPs) decaying into two photons.
The...
If the temperature of the hot thermal plasma in the Early Universe was within a few orders of magnitude of the quantum gravity scale, then the hoop conjecture predicts the formation of microscopic black holes from particle collisions in the plasma. These black holes may evaporate and produce the dark matter relic abundance observed today for a wide variety of dark matter masses. We study the...
Inflationary models with solid described through a triplet of fields with homogeneous and isotropic properties are consistent with observations [1] and at the same time predict unique nonlinear properties of primordial perturbations [2]. A problematic feature is the possibility of superluminal propagation of perturbations, which considerably restricts the parameter space of studied models....
Whether the magnetic monopole (MM) exists is a long-standing question in particle physics.
It is postulated to be crucially related to the quantization of the electric charge. Under the framework of the Grand Unified Theory (GUT), a certain amount of MMs are produced during the splitting between strong and electroweak forces, which occurred very shortly after the big bang. Past efforts were...
The origin of dark energy is one of the greatest puzzles in modern physics. Amending general relativity by the so-called cosmological constant $\Lambda$ allows to describe an accelerated expansion. However, such a procedure would lead to a severe fine-tuning problem with many unresolved questions. Consequently, the existence of new hypothetical scalar fields has been postulated, which couple...
We present a new dark matter (DM) scenario intimately linked to the baryon asymmetry of the visible sector. We question one of the Sakharov conditions: baryon number violation. We provide a framework where the dark sector carries an opposite but precisely compensating baryon asymmetry to that of the visible sector, therefore conserving baryon number at all times. Within an effective field...
If the mediator in a given $2\to 2$ $t$-channel process is kinematically allowed to be on-mass-shell, the matrix element can become singular. For a massive and stable mediator, this singularity cannot be regularized using the usual methods, like Dyson resummation of self-energy contributions, or infra-red regularization schemes.
Models of particle dark matter are especially affected by this...
In the 3+1 neutrino scheme with an additional state, we consider the thermalisation of neutrinos in the early Universe in the so-called very low reheating scenarios. This process could be incomplete due to the lack of interactions, leading to a reduced contribution of neutrinos to the cosmological energy density of radiation. We calculate this contribution, usually measured in terms of the...
We discuss thermal leptogenesis in the framework of the flipped SU(5) unification model, where the Majorana masses of neutrinos are generated through Witten's two-loop mechanism.
Our analysis shows that this model is compatible with the current experimental constraints on both the neutrino sector and observed baryon asymmetry. Moreover, it indicates an upper (and lower) limit on the absolute...
We study the phenomenological properties of the three-loop radiative seesaw model proposed by Krauss, Nasri, and Trodden. In this model, the tininess of the neutrino masses and there is a dark matter candidate. We show constraints on the parameter space of this model by mainly considering the DM relic density, the lepton flavour violation constraints, and neutrino oscillation data.
We also...
The sexaquark, a hypothesized six-quark bound state, has garnered interest as a potential dark matter candidate. At the same time, there are many arguments in the literature that place severe limitations on this possibility. Assuming it exists and is stable, I will advance a compelling case for the limited viability of the sexaquark as a dark matter candidate by presenting the first...
The wealth of theoretical and phenomenological information about Quantum Chromodynamics (QCD) at short and long distances collected so far in major collider measurements has profound implications in cosmology. We provide a brief discussion on the significant implications of the strongly coupled dynamics of quarks and gluons and the effects due to their collective motion on the physics of the...
