Le boson de Higgs sait probablement des choses sur la matière noire et l'inflation (chapitre 4)
Qu'est-ce que le boson de Higgs sait que nous ne sav(i)ons pas?Darkon et Inflaton
... non-collider experimental results confront the Standard Model (SM) with two major puzzles: neutrino masses and dark matter. The phenomenon of neutrino oscillations show that at least two neutrinos have nonzero but small masses located around sub-eV scale. Evidences from astrophysics and cosmology have pointed out that the ordinary baryonic matter is not the dominant form of material in the Universe. Rather, about 23% of energy density of the Universe is non-luminous and non-absorbing matter, called dark matter (DM). Enclosing dark matter and the massiveness of neutrino into SM may have effects on the Higgs sector for the analysis of stability of vacuum. Although the exact nature of dark matter and neutrino mass is still unknown and their interactions with SM particle vary for different models, there exist several guidelines for our purpose to analyze the vacuum stability. Based on Standard Model (SM) gauge structure and changing the SM Higgs potential in a controllable way, the model should introduce new particles as less as possible to make the analysis of stability possible and necessary... One of the popular DM candidates is the weakly interacting massive particle (WIMP) which is stable on cosmological time scale and a thermal relic of the Big Bang. Typically, one of the simplest way to justify the stability of DM is to impose a Z2 parity symmetry, for example the R-parity in supersymmetry. [One model is] the darkon: The SM with an additional real singlet scalar S, called darkon.
Chian-Shu Chen et Yong Tang, Vacuum stability, neutrinos, and dark matter, 26/02/2012
No hint of new physics beyond the SM has been found so far at the LHC up to 1 TeV. It is important to examine up to what scale the SM can be a valid effective description of nature. The determination of the Higgs mass finally fixes all the parameters in the SM. We can now obtain the bare parameters at the ultraviolet (UV) cutoff scale Λ. These parameters are important. If a UV theory such as string theory fails to fit them, it is killed...After fixing all the dimensionless bare couplings, the last remaining parameter in the SM is the bare Higgs mass. The quadratically divergent bare Higgs mass is found to be suppressed too when the UV cutoff is Λ ≅ 1017GeV. ...The Higgs potential in the Standard Model (SM) can have a saddle point around 1017 GeV and its height is suppressed because the Higgs quartic coupling becomes small. These facts suggest that the SM Higgs field may serve as an inflaton, without assuming the very large coupling to the Ricci scalar of order 104, which is necessary in the ordinary Higgs inflation scenario. In this paper, we have pursued the possibility that the Higgs potential becomes almost flat above the UV cutoff Λ. Since a first order phase transition at the end of the inflation leads to the graceful exit problem, the Higgs potential must be monotonically increasing in all the range below and above. From this condition, we get an upper bound on to be ∼ 1017 GeV.... even if we allow arbitrary potential above Λ, still the restriction is rather severe to achieve this minimal Higgs inflation scenario. It is curious that the upper bound on from the minimal Higgs inflation coincides with the scale where the quartic coupling and its beta function (and possibly the bare Higgs mass) vanish. This coincident scale around 1017GeV is close to the string scale in the conventional perturbative superstring scenario. This fact may suggest that the physics of the SM, string theory, and the universe are all directly connected.
Yuta Hamada, Hikaru Kawai,y and Kin-ya Oda, Minimal Higgs inflation, 30/08/2013
//ajout du 27/01/14
La solution au problème de la divergence quadratique de la masse du boson de Higgs abordée dans l'extrait précédent est très spécifique et l'hypothèse qui la sous-tend ne peut être testée que de façon très indirecte via des observations astrophysiques et un modèle cosmologique donné. Aussi reviendrons nous dans le prochain billet sur une autre solution beaucoup plus générique au problème de stabilité lié au boson de Higgs, une solution qui présente surtout l'intérêt d'être testable directement au LHC, je veux parler de la supersymétrie bien sûr ...