39 research outputs found
Radiative corrections to the Triple Higgs Coupling in the Inert Higgs Doublet Model
We investigate the implication of the recent discovery of a Higgs-like
particle in the first phase of the LHC Run 1 on the Inert Higgs Doublet Model
(IHDM). The determination of the Higgs couplings to SM particles and its
intrinsic properties will get improved during the new LHC Run 2 starting this
year. The new LHC Run 2 would also shade some light on the triple Higgs
coupling. Such measurement is very important in order to establish the details
of the electroweak symmetry breaking mechanism. Given the importance of the
Higgs couplings both at the LHC and
Linear Collider machines, accurate theoretical predictions are required. We
study the radiative corrections to the triple Higgs coupling and to
, couplings in the context of the IHDM. By combining several
theoretical and experimental constraints on parameter space, we show that extra
particles might modify the triple Higgs coupling near threshold regions.
Finally, we discuss the effect of these corrections on the double Higgs
production signal at the LC and show that they can be rather
important.Comment: 25 pages, 10 figure
Boosting dark matter searches at muon colliders with Machine Learning: the mono-Higgs channel as a case study
The search for dark-matter (DM) candidates at high-energy colliders is one of
the most promising avenues to understand the nature of this elusive component
of the universe. Several searches at the Large Hadron Collider (LHC) have
strongly constrained a wide range of simplified models. The combination of the
bounds from the LHC with direct-detection experiments exclude the most minimal
scalar singlet DM model. To address this, Lepton portal DM models are suitable
candidates where DM is predominantly produced at lepton colliders since the DM
candidate only interacts with the lepton sector through a mediator that carries
a lepton number. In this work, we analyse the production of DM pairs in
association with a Higgs boson decaying into two bottom quarks at future muon
colliders in the framework of the minimal lepton portal DM model. It is found
that the usual cut-based analysis methods fail to probe heavy DM masses for
both the resolved (where the decay products of the Higgs boson can be resolved
as two well-separated small- jets) and the merged (where the Higgs boson is
clustered as one large- jet). We have then built a search strategy based on
Boosted-Decision Trees (BDTs). We have optimised the hyperparameters of the BDT
model to both have a high signal-to-background ratio and to avoid overtraining
effects. We have found very important enhancements of the signal significance
with respect to the cut-based analysis by factors of -- depending on the
regime (resolved or merged) and the benchmark points. Using this BDT model on a
one-dimensional parameter space scan we found that future muon colliders with
TeV and can exclude DM masses up to
TeV at the CL.Comment: 22 pages, 9 figures, and 11 table
Scalar leptoquarks at the LHC and flavour anomalies: a comparison of pair-production modes at NLO-QCD
We analyse scalar leptoquark pair production at the LHC with predictions including t-channel lepton exchange contributions up to next-to-leading order (NLO) in QCD. In particular, we calculate NLO-QCD predictions for off-diagonal production channels, i.e. channels that involve two different leptoquark eigenstates and are driven solely by diagrams involving Standard Model leptons in the t-channel at leading order, as opposed to diagonal channels where a pair of the same leptoquark eigenstate is produced. We find that reliable theoretical predictions for both channels require NLO accuracy. The relative importance of the off-diagonal modes depends strongly on the considered scenario. In a generic model involving R and S leptoquarks, at large values of the Yukawa couplings off-diagonal contributions initiated by valence quarks can be up to an order of magnitude higher than the diagonal production. However, we also find that in phenomenologically viable scenarios addressing the flavour anomalies off-diagonal production is generally negligible, with a few exceptions of 10%β30% of the total rate depending on the treatment of the charm density in the proton
Scalar leptoquarks at the LHC and flavour anomalies: a comparison of pair-production modes at NLO-QCD
We analyse scalar leptoquark pair production at the LHC with predictions including t-channel lepton exchange contributions up to next-to-leading order (NLO) in QCD. In particular, we calculate NLO-QCD predictions for off-diagonal production channels, i.e. channels that involve two different leptoquark eigenstates and are driven solely by diagrams involving Standard Model leptons in the t-channel at leading order, as opposed to diagonal channels where a pair of the same leptoquark eigenstate is produced. We find that reliable theoretical predictions for both channels require NLO accuracy. The relative importance of the off-diagonal modes depends strongly on the considered scenario. In a generic model involving R and S leptoquarks, at large values of the Yukawa couplings off-diagonal contributions initiated by valence quarks can be up to an order of magnitude higher than the diagonal production. However, we also find that in phenomenologically viable scenarios addressing the flavour anomalies off-diagonal production is generally negligible, with a few exceptions of 10%β30% of the total rate depending on the treatment of the charm density in the proton