Conveners
Particle cosmology: Theory and Experiment
- Leandros Perivolaropoulos (U. of Ioannina)
- Vassilis Spanos (Department of Physics National and Kapodistrian University of Athens)
Particle cosmology: Theory and Experiment
- Nicolaos Toumbas (University of Cyprus)
Particle cosmology: Theory and Experiment
- Konstantinos Dimopoulos
The Higgs sector of the Next-to-Minimal Supersymmetric Standard Model can accommodate explicit CP-violating phases at the tree level, unlike the minimal scenario. In particular, the phase of the parameter that governs the singlet-singlino mass is relevant for the phenomenology of the dark matter in the model also, when R-parity is conserved. A small magnitude of this parameter can yield a...
The nature of dark matter, one of the major components of the cosmic
standard model, remains one of the outstanding problems in physics. One
interesting model is scalar field dark matter (SFDM), which fits naturally
into observations in both particle physics and cosmology. Simulations and
calculations using SFDM often use a classical field approximation (MFT) of
the underlying quantum...
The quest for Dark Matter (DM) and its nature has been puzzling scientists for nearly a century. This puzzle has engendered theories that span nearly hundred orders of magnitude in mass scales with widely contrasting nature. It has also motivated decades of experimental efforts correspondingly different in the wide variety of their target masses, observables, technologies and interpretations....
We study a minimal model for light scalar dark matter (DM) which requires a light scalar mediator to address the core-cusp problem as well as to interact with the standard model. We focus on the Breit-Wigner resonance for the DM annihilation and self-scattering channels. The thermally-averaged annihilation cross-section of DM has strong temperature dependence, whereas its energy exchange by...
We study models of cosmic inflation in order to explain the production of primordial black holes (PBHs), which can amount of a significant fraction of dark matter (DM) in the universe and the induced gravitational waves (GWs). In particular, we present mechanisms which lead to an enhancement of the scalar power spectrum at small scales. This amplification can explain the generation of PBHs and...
The twin Higgs framework offers an explanation of the little hierarchy problem while remaining consistent with the bounds on new colored states. This scenario also offers a concrete model of richly varied hidden sectors. Typically, the twin sector includes a SU(3) confining force which binds the twin quarks into hadrons. I outline how twin color can be spontaneously broken. In this case the...
A toy-model is presented, which considers two flat directions meeting at an enhanced symmetry point such that they realise the usual hybrid inflation mechanism. The kinetic term of the waterfall field features a pole at its Planckian vacuum expectation value (VEV), as in alpha-attractors. Consequently, after the phase transition which terminates hybrid inflation, the waterfall field never...
I will present a recently proposed approach to detect photon-coupled dark matter axions in an RF cavity. The approach relies on axion-mediated transitions between nearly-degenerate resonant modes, leading to parametrically enhanced signal power for light axions. We will discuss how a resonant signal is generated, and how it compares with traditional haloscope searches. We will also discuss...
We study the impact of sphaleron-induced thermal friction on the axion dark-matter abundance due to the interaction of an axion-like particle (ALP) with a dark non-abelian gauge sector in a secluded thermal bath. Thermal friction can either enhance the axion relic density by delaying the onset of oscillations or suppress it by damping them. We derive an analytical formula for the frictional...
We consider hybrid inflation models in the framework of no-scale supergravity. $U(1)_R$ symmetry can be broken on the renormalizable level or by Planck suppressed non-renormalizable operators. We show that a Starobinsky like inflation can be realized with asymptotically flat potentials for specific region of parameter space. A connection to the low energy physics as well as the neutrino...
LUX-ZEPLIN (LZ) is a direct detection dark matter experiment hosted in the Davis Campus of the Sanford Underground Research Facility in Lead, South Dakota. LZโs central detector is a dual-phase time projection chamber containing 7 tonnes of liquid xenon (LXe), 5.6 tonne fiducial mass, and is aided by a LXe โskinโ detector and liquid scintillator-based outer detector to veto events inconsistent...
One signature of an expanding universe is the time variation of the cosmological abundances of its different components. For example, a radiation-dominated universe inevitably gives way to a matter-dominated universe, and critical moments such as matter-radiation equality are fleeting. In this talk, I will stress that this lore is not always correct and that it is possible to obtain a form of...
We study in detail the viability and the patterns of a strong first-order electroweak phase transition as a prerequisite to electroweak baryogenesis in the framework of $Z_3$-invariant Next-to-Minimal Supersymmetric Standard Model (NMSSM), in the light of recent experimental results from the Higgs sector, dark matter (DM) searches and those from the searches of the lighter chargino and...
We show that the type-I seesaw, responsible for generating the light neutrino mass, itself is capable of accommodating one of the three right handed neutrinos as a freeze-in type of dark matter (DM) where the required smallness of the associated coupling is connected to the lightness of the (smallest) active neutrino mass. It turns out that (a) the non-thermal production of DM having mass...
Commonly known as Boltzmann suppression is the key ingredient to create chemical imbalance for thermal dark matter. In a degenerate/quasi degenerate dark sector chemical imbalance can also be generated from a different mechanism which is analogous to the radioactive decay law, known as co-decaying dark matter. In this work, we have studied the dynamics of a multicomponent thermally decoupled...
Baryogenesis, the process that is theorised to have happened in the beginning of the Universe which produced the observed baryonic asymmetry, remains one of the most fundamental problems in physics. Baryon number violation (BNV) is ordinarily required for baryogenesis, but so far, all searches for it came back negative. The HIBEAM/NNBAR program is a two stage set of experiments (HIBEAM then...
A low reheating temperature is predicted by many supersymmetric extensions of the Standard Model. This implies that an extended early matter domination era (eMD) might have occurred in the universe during the first seconds of the cosmic evolution. In this talk I will present how the density perturbations grow and primordial black holes (PBHs) can form during eMD. Emphasis will be given to the...
We investigate the impact of Coleman-Weinberg inflation on the stochastic gravitational wave background spectrum emitted by intermediate-scale cosmic strings. The string network is partially inflated and reenters the horizon at later times after the end of inflation, such that the short string loops are not produced. This leads to a significant modification of the gravitational wave spectrum...
