Conveners
Cosmology & Gravitational Waves: I
- Marco Drewes (Technische Universitaet Muenchen (DE))
Cosmology & Gravitational Waves: II
- David Richard Harvey (EPFL - EPF Lausanne)
Cosmology & Gravitational Waves: III
- David Richard Harvey (EPFL - EPF Lausanne)
Cosmology & Gravitational Waves: IV
- Damir Buskulic (LAPP / Université Savoie Mont Blanc)
I will discuss, in a model-independent way, how the nature of the electroweak phase transition is completely changed when the Standard Model Yukawas vary at the same time as the Higgs is acquiring its vacuum expectation value. (Large Yukawas before the electroweak phase transition also give an unsuppressed source of CP violation, see abstract/talk by Sebastian Bruggisser.) The thermal...
Varying Yukawas open new possibilities for electroweak baryogenesis. In this talk I will focus on the CP-violation and the baryon-asymmetry (for details on the strength of the phase transition, see abstract by Iason Baldes). Starting from first principles, I will derive the general form of the CP-violating semiclassical force and the diffusion equations for models with varying Yukawa...
Interactions that manifest themselves as lepton number violating processes at low energies in combination with sphaleron transitions typically erase any pre-existing baryon asymmetry of the Universe. We demonstrate in a model independent approach that the observation of lepton number violation, namely in neutrinoless double beta decay and at the LHC, would impose a stringent constraint on...
In this talk I will start by considering a question which curiously had not been properly considered so far: in the standard seesaw model what is the minimum value the mass of a right-handed (RH) neutrino must have for allowing successful leptogenesis via CP-violating decays? I show that, for low RH neutrino masses and thanks to thermal effects, leptogenesis turns out to proceed efficiently...
The extension of the Standard Model by heavy right-handed neutrinos can simultaneously explain the observed neutrino masses via the seesaw mechanism and the baryon asymmetry of the Universe via leptogenesis. If the mass of the heavy neutrinos is below the electroweak scale, they may be found at LHCb, BELLE II, the proposed SHiP experiment or a future high-energy collider. In this mass range,...
- Present circumstantial evidences that seem to favour a scenario of baryogenesis via
leptogenesis from heavy particle decays - New experimental results that could further support this picture in the next future
- Difficulties for going beyond the level of "circumstantial evidences in favour...".
General no-go arguments forbidding leptogenesis scales sufficiently low to be directly
...
Under general circumstances, the Standard Model Higgs is excited in the form of a condensate during or towards the end of inflation. The Higgs condensate is then forced to decay afterwards — due to non-perturbative effects — into the rest of the SM species. I will present the cosmological implications of this primordial decay, quantifying the necessary conditions to achieve a successful...
We investigate the production of gravitational waves during the preheating process after inflation in the common case of field potentials that are asymmetric around the minimum where the universe reheats. In particular, we study the impact of oscillons, comparatively long lived and spatially localized regions where a scalar field (e.g. the inflaton) oscillates with large amplitude. Contrary to...
Status of eLISA; Gravitational waves from first-order phase transitions; BSM physics with first-order phase transitions.
Gravitational waves are a promising new observational tool, not only for astrophysics but also for cosmology. In various extensions of the Standard Model the phase transition can be first order, and could produce copious gravitational waves from bubble collisions. Other possibilities, such as a tachyonic transition at the electroweak scale, produce a more subdued signature at higher...
We report on the ?first joint analysis of observational signatures from the electroweak baryogenesis
in both gravitational wave (GW) detectors and particle colliders to explore the nature of the electroweak phase transtion. Working with both the effective field theory and concrete models ,we show that a modified Higgs potential can keep the observed 125 GeV Higgs mass and produce a strong...
We investigate the capability of various configurations of the space interferometer eLISA to probe the late-time background expansion of the universe using gravitational wave standard sirens. We simulate catalogues of standard sirens composed by massive black hole binaries whose gravitational radiation is detectable by eLISA, and which are likely to produce an electromagnetic counterpart...
Calculating the neutralino relic density is a strong possibility to identify favoured and disfavoured regions of the parameter space of a supersymmetric theory such as the MSSM. With the latest results of the Planck mission, the cosmological parameters including the dark matter abundance are determined to an unprecedented precision. In order to reduce the theoretical uncertainty in the...
A trilinear coupling between an inflaton and the Standard Model Higgs boson opens up an exponentially enhanced decay channel. Such a coupling is for instance generically present in a combined Goldstone Inflation and Composite Higgs scenario. Here I will discuss our analysis of such a scenario and its constraints, paying attention to both the feasibility of the production of Standard Model...
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A mixed dark matter model consists of a cold dark matter (CDM) fraction and a fraction given by another dark component (non-cold). The free-streaming length increases with the velocity of the dark matter particle, varying from a scale value of Mpc for a warm dark matter component up to the size of Universe for a relativistic species that we label as dark radiation.
We study these models...
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Scalar-tensor modifications of gravity have long been considered as an alternative explanation for the late-time accelerated expansion of our Universe. I will first show that a rigorous discrimination between acceleration from modified gravity and from a cosmological constant or dark energy is not possible with observations of the large-scale structure alone. I will then demonstrate how...
Advanced LIGO's first scientific run, between September 2015 and January 2016, will be
historically remembered for the first direct detection of gravitational waves from an
astrophysical source. This run also provided the first direct evidence for the existence
of stellar-mass black hole binaries. In this talk, we will present details of the
detected sources, their astrophysical...
Gravitational-wave astronomy has made a tremendous stride forward with detections during the first observing run of the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO). The signals have been identified as originating from the merger of black holes, whose parameters it was possible to infer.
In this talk I will explain how the parameter inference from gravitational-wave...
Advanced LIGO's direct observation of gravitational radiation from a binary black hole merger has sent quakes through the physics and astronomy community. In a few short years, the search for gravitational waves will complete its transformation from an experimental effort into a new discipline of observational astronomy as we rapidly build a sample of merging compact binaries. However, the...
We have entered the advanced era for ground-based gravitational wave detectors in dramatic fashion. The improvement in sensitivity also benefits searches for continuous gravitational waves. Here I summarize the current activities, and plans for the future, of continuous wave searches in Advanced LIGO and Virgo data.
The direct detection of gravitational waves with Advanced LIGO has opened up the possibility of probing the genuinely strong-field dynamics of pure spacetime for the first time. Several tests of general relativity (GR) were carried out with the gravitational wave events GW150914 and GW151226. In the case of GW150914, the merger itself was in the most sensitive part of the detectors' frequency...
A stochastic background of gravitational waves can be described as a superposition of several uncorrelated contributions. It can be of both cosmological and astrophysical origin. In the first case, it can constitute potentially a unique probe of the primordial universe. In the second, it can give precious information on stellar populations.
After discussing how this kind of signal can be...
