Journal Club

Seminar Room

If you want to propose a paper, you can contact Supratim Das Bakshi (sdb AT

Tuesday 22nd of March, 2022

The hidden side of scalar-triplet models with spontaneous CP violation

Scalar triplet extensions of the Standard Model provide an interesting playground for the explanation of neutrino mass suppression through the type-II seesaw mechanism. Propelled by the possible connections with leptonic CP violation, we explore under which conditions spontaneous CP violation can arise in models with extra scalar triplets. The minimal model satisfying such conditions requires adding two such triplets to the SM field content. For this model, the scalar mass spectrum in both the CP-conserving and spontaneous CP-violating scenarios is studied. In the former case, a decoupling limit for the new scalars can be achieved, while this is not the case when CP is spontaneously broken. In particular, we show that the existence of two light neutral scalars with masses below a few tenths of GeVs is unavoidable in the CP-violating case. Using matrix theory theorems, we derive upper bounds for the masses of those light scalars and briefly examine whether they can still be experimentally viable. Other interesting features of the scalar mass spectrum are discussed as, e.g., the existence of relations among the charged and neutral scalar masses.
Comments: 29 LaTeX pages; 4 figures. Typos corrected, comments and references added
Subjects: High Energy Physics - Phenomenology (hep-ph)
Report number: CFTP/21-012
Cite as: arXiv:2109.13179 [hep-ph]
  (or arXiv:2109.13179v2 [hep-ph] for this version)

Submission history

From: Bernardo Gonçalves [view email] 
[v1] Mon, 27 Sep 2021 16:46:45 UTC (1,120 KB)
[v2] Wed, 19 Jan 2022 17:07:44 UTC (1,122 KB)

Presented by Miki



Search for pair-produced vector-like leptons in  3b τ final states


Abstract: A search for vector-like leptons (VLLs) is presented in the context of the 4321 model, a UV-complete
model with the potential to explain existing B-physics measurements that are in tension with standard model
predictions. The analyzed data correspond to an integrated luminosity of 97 fb1, and were recorded by the CMS
detector at the LHC in proton-proton collisions at √s=13 TeV at the LHC. Final states with 3 b jets and two
third-generation leptons (ττ,τντ, or ντντ) are targeted. Expected upper limits are derived on the VLL production
cross section in the VLL mass range 500-1050 GeV, assuming only electroweak production. At the low end of this
mass range, the expected limits are below the expected production cross section, whereas at the high end of the
mass range the expected upper limits on the production cross section are several times higher than the expected
cross section for electroweak production. A mild excess, consistent with a possible signal, is observed in the data,
such that the observed upper limits are approximately double the expected limits. The maximum likelihood fit
prefers the presence of signal at the level of 2.8σ, for a representative VLL mass point of 600 GeV.

See also the following talk at Moriond EW 2022:

Presented by Javi