NExT Seminar Meeting

Wednesday 10 Nov 2021, 13:00 → 18:55 GMT

Building 2/ Room 1085 (Lecture Theatre) (University of Southampton)

Teams link

University of Southampton Map

1 Low mass H+ -> WA, A->mumu

The search for an A boson produced in the decay chain t->H+->A and using the A->mumu channel in the ATLAS experiment is reported. Requirements on 3 jets, a bet and an electron enhance the selection in top quarks, but no explicit H+ reconstruction is done. The analysis covers a charged Higgs mass range 100 to 160 GeV and a range of A masses from 15 to 75 GeV. No significant excess is observed and limits are set on tan beta in the mA,mH+ plane using a 2HDM. Input is sought on the next steps.

Speaker: Bill Murray (University of Warwick (GB))

next-20211109a.odp

next-20211109a.pdf

next-20211109a.pdf

I cannot work out how to connect to the teams meeting. Sorry.

2 Recasting searches for light BSM Higgs Onto 2HDM Type-I parameter space

The talk discusses the reinterpretation study of the existing results from the CMS Collaboration, specifically, searches for light BSM Higgs pairs produced in the chain decay pp→H(SM)→hh(AA) into a variety of final states. Through this, we test the LHC sensitivity to other possible new signatures to investigate in the future, like pp→H(SM)→ZA→ZZh, by taking advantage of strong correlations between these processes existing in, e.g., the 2HDM type-I

Speaker: Ms Souad Semlali (University of Southampton)

Talk.pdf

3 Type Ib seesaw model in the Early Universe

We study the connection between the masses and mixing of neutrinos and two cosmological indications of physics beyond the Standard Model (SM): the existence of dark matter and baryon asymmetry. Motivated by the testability, we consider a type Ib seesaw model instead of the traditional type I seesaw model, where the effective neutrino mass operator involves two different Higgs doublets and two right-handed neutrinos forming a single heavy Dirac pair. To account for DM, we consider two different extensions of the type Ib seesaw model: a neutrino portal extension and a U(1) gauge extension. To explain the baryon asymmetry (BAU), we construct an effective realisation of the type Ib seesaw mechanism which makes it possible to produce a correct baryon asymmetry through resonant leptogenesis. We explore the parameter space of variant models consistent with both oscillation data and observational results. Within this framework, we show how the results can be directly related to laboratory experiments for relatively low scale heavy Dirac neutrino.

Speaker: Bowen Fu (University of Southampton)

TypeIb.pdf

4 Top quark mass corrections to NNLO double Higgs boson production

In this talk, I will discuss recent computations of the top quark mass dependence of NNLO double Higgs boson production, including both the real and virtual contributions. The dependence is computed in the large top quark mass limit, which is particularly useful for processes that are dominated by top quarks running in loops.

Speaker: Mr Joshua Davies (University of Sussex)

slides.pdf

15:00 Coffee/Tea break

5 Fermiophobic Z' model for simultaneously explaining the muon anomalies RK(*) and (g-2)μ

We discuss a simple renormalisable, gauge-invariant model with a fermiophobic Z' boson: it has no couplings to the three Standard Model chiral families but does couple to a fourth heavy vector-like family. This model can simultaneously account for the measured B-decay ratios RK(*) and the muon anomalous magnetic moment (g −2)μ. We identify the parameter space where this explanation is consistent with existing experimental constraints coming from Bs mixing, neutrino trident production and collider searches.

Speaker: Mr Mario Fernandez Navarro (University of Southampton)

NExT_seminar_MFN.pdf

6 Explaining B anomalies with Planck-safe Z'

I will present a family of Z' extensions of the SM featuring generation-dependent couplings to quarks and leptons, vector-like BSM fermions and flavourful scalars as well as optional right-handed neutrinos. These theories can account for the flavour anomalies observed in B meson decays, avoid Landau poles and remain predictive until the Planck scale as well as stabilise the Higgs potential altogether. The phenomenological viability of the models and their potential to be probed at future colliders are discussed.

Speaker: Mr Tom Steudtner (University of Sussex)

Steudtner.pdf

7 Probing New Physics Through Flavor Anomalies

Speaker: Shaaban Khalil Ibrahim (ENHEP Egyptian Network of High Energy Physics (EG))

BSM_Flavor.pdf

8 Charged-lepton-flavor violation from Lorentz and CPT violation

Lorentz and CPT invariance are among the most fundamental and tested symmetries in physics. However, the class of Lorentz- and CPT-violating interactions that induce charged-lepton-flavor transitions remains largely unstudied. Dominant Lorentz- and CPT-violating operators initiating flavor-changing tau and muon decays are analyzed. Coupled with measurements from the MEG and BaBar collaborations, several first constraints are placed on flavor off-diagonal coefficients for Lorentz violation. The outlook for improved constraints in future experiments is also discussed.

Speaker: Nathaniel Sherrill (University of Sussex)

NExT_2021_pdf.pdf