Baryogénèse

Résumé

vignette|upright=2|La baryogénèse se serait produite après l'inflation (en beige), mais bien avant la première seconde suivant le Big Bang. Elle se situerait dans les parties jaune-orange du schéma ci-dessus. En cosmologie, le terme baryogénèse désigne une ou des périodes de formation des baryons au sein de l'univers primordial. Ainsi, d'après la théorie du Big Bang, lors des premiers instants de l'Univers, ce dernier était trop chaud pour permettre l'existence de la matière. Cette dernière se serait formée à partir du moment où l'Univers est devenu suffisamment froid pour ce faire. L'époque de la baryogénèse n'est pas connue avec certitude. Elle se situerait entre 10-32 et 10-12 s après le Big Bang (cf. #Modèles). Les principales hypothèses situent la baryogénèse dans deux ères : la baryogénèse de grande unification se serait produite pendant ou peu après l'ère de grande unification ; la baryogénèse électrofaible se serait produite lors de la transition électro-faible. À la suite d

Source officielle

https://fr.wikipedia.org/wiki/Baryog%C3%A9n%C3%A8se

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Effective Field Theories for New and Old Physics

Alfredo Glioti

Effective Field Theories have changed our understanding of Quantum Field Theories. This thesis shows several applications of this powerful tool in the context of the Standard Model and for searches of New Physics.The thesis starts with a review of the Standard Model and its open questions and is followed by an updated and systematic study of models of flavor in the context of Partial Compositeness in Composite Higgs theories. Following that, the question on how to measure the Wilson coefficients of the Standard Model effective operators at present and future experiments is addressed: first by using modern Machine Learning techniques by studying angular distributions for diboson production, followed then by a study on ElectroWeak radiation at a future Muon Collider and how to use it to better probe the new physics parameter space.The fourth chapter deals instead with applying Non-Relativistic Effective Theories to the study of exotic mesons in the Standard Model. The two competing interpretations, a molecule formed of two mesons or a compact tetraquark state, and their consequences are studied. In particular this study is done on the X(3872) exotic charmonium and the consequences of the two accidental tunings of this system are discussed.The last chapter addresses the problem of baryogenesis from the ElectroWeak phase transition. A new scalar sector is introduced that decouples the physics responsible for the generation of the baryon asymmetry from the weak scale. This helps solving the main problems that ElectroWeak baryogenesis models face, namely the large modifications to the Higgs physics and the need of large CP violating new effects.

EPFL2022

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Initial condition for baryogenesis via neutrino oscillation

Shintaro Eijima

We consider a baryogenesis scenario via the oscillation of right-handed neutrinos with Majorana masses of the order of GeV, which are also responsible for neutrino masses by the seesaw mechanism. We study how the initial condition alters the prediction of the present baryon asymmetry by this mechanism. It is usually assumed that the abundance of right-handed neutrinos is zero after the reheating of the inflationary universe and they are produced in scattering processes by the renomalizable Yukawa interaction. However, the higher-dimensional operator with right-handed neutrinos may provide an additional production which is most effective at the reheating epoch. It is shown that such an initial abundance of right-handed neutrinos can significantly modify the prediction when the strong washout of the asymmetry is absent. This leads to the parameter space of the model for the successful baryogenesis being enlarged.

Amer Physical Soc2017

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, ,

Conventional scenarios of electroweak (EW) baryogenesis are strongly constrained by experimental searches for CP violation beyond the SM. We propose an alternative scenario where the EW phase transition and baryogenesis occur at temperatures of the order of a new physics threshold far above the Fermi scale, say, in the 100-1000 TeV range. This way the needed new sources of CP-violation, together with possible associated flavor-violating effects, decouple from low energy observables. The key ingredient is a new CP- and flavor-conserving sector at the Fermi scale that ensures the EW symmetry remains broken and sphalerons suppressed at all temperatures below .We analyze a minimal incarnation based on a linear O(N) model. We identify a specific large-N limit where the effects of the new sector are vanishingly small at zero temperature while being significant at finite temperature. This crucially helps the construction of realistic models. A number of accidental factors, ultimately related to the size of the relevant SM couplings, force N to be above approximate to 100. Such a large N may seem bizarre, but it does not affect the simplicity of the model and in fact it allows us to carry out a consistent re-summation of the leading contributions to the thermal effective potential. Extensions of the SM Higgs sector can be compatible with smaller values N approximate to 20-30.Collider signatures are all parametrically suppressed by inverse powers of N and may be challenging to probe, but present constraints from direct dark matter searches cannot be accommodated in the minimal model. We discuss various extensions that satisfy all current bounds. One of these involves a new gauge force confining at scales between approximate to 1 GeV and the weak scale.

Springer2019

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