Light Higgs Pair Research Articles

Heavy to light Higgs boson decays at NLO in the singlet extension of the Standard Model

We study the decay of a heavy Higgs boson into a light Higgs pair at one loop in the singlet extension of the Standard Model. To this purpose, we construct several renormalization schemes for the extended Higgs sector of the model. We apply these schemes to calculate the heavy-to-light Higgs decay width at next-to-leading order electroweak accuracy, and demonstrate that certain prescriptions lead to gauge-dependent results. We comprehensively examine how the NLO predictions depend on the relevant singlet model parameters, with emphasis on the trademark behavior of the quantum effects, and how these change under different renormalization schemes and a variable renormalization scale. Once all present constraints on the model are included, we find mild NLO corrections, typically of few percent, and with small theoretical uncertainties.

Dynamical generation of flavour

We propose the generation of Standard Model fermion hierarchy by the extension of renormalizable SO(10) GUT with O(N g ) family gauge symmetry. In this scenario, Higgs representations of SO(10) also carry family indices and are called Yukawons. Vacuum expectation values of these Yukawon fields break GUT and family symmetry and generate MSSM Yukawa couplings dynamically. We have demonstrated this idea using ${\mathbf {10}}\oplus {\mathbf {210}} \oplus {\mathbf {126}} \oplus {\overline {\mathbf {126}}}$ Higgs irrep, ignoring the contribution of 1 2 0-plet which is, however, required for complete fitting of fermion mass-mixing data. The effective MSSM matter fermion couplings to the light Higgs pair are determined by the null eigenvectors of the MSSM-type Higgs doublet superfield mass matrix $\mathcal {H}$ . A consistency condition on the doublet ([1,2,±1]) mass matrix ( $\text {Det}(\mathcal {H})=$ 0) is required to keep one pair of Higgs doublets light in the effective MSSM. We show that the Yukawa structure generated by null eigenvectors of $\mathcal {H}$ are of generic kind required by the MSSM. A hidden sector with a pair of (S a b ; ϕ a b ) fields breaks supersymmetry and facilitates $D_{O(N_{g})}\hspace *{-1pt}=$ 0. SUSY breaking is communicated via supergravity. In this scenario, matter fermion Yukawa couplings are reduced from 15 to just 3 parameters in MSGUT with three generations.

Next-to-next-to-leading order QCD corrections to light Higgs pair production via vector boson fusion in the type II two-Higgs-doublet model

We present the precision predictions on the pair production of light, $CP$-even Higgs boson in weak vector boson fusion (VBF) up to the QCD next-to-next-to-leading order (NNLO) at hadron colliders within the $CP$-conserving type II two-Higgs-doublet model [2HDM(II)] by adopting the structure function approach. We investigate the model parameter dependence, residual uncertainties from the factorization/renormalization scale, PDFs, and ${\ensuremath{\alpha}}_{s}$ on the integrated cross section at the QCD NNLO and find that the NNLO QCD corrections can reduce the scale uncertainty significantly. By analyzing the kinematic distributions of final Higgs bosons, we can extract the $CP$-even Higgs resonance via the ${H}^{0}\ensuremath{\rightarrow}{h}^{0}{h}^{0}$ channel as a means of probing the extension of the standard model (SM) Higgs sector.

Production of light Higgs pairs in 2-Higgs doublet models via the Higgs-strahlung process at the LHC

At the Large Hadron Collider, we prove the feasibility to detect pair production of the lightest CP-even Higgs boson h of a Type II 2-Higgs Doublet Model through the process q \bar q' --> Vhh (Higgs-strahlung, V=W+-,Z), in presence of two h --> b \bar b decays. We also show that, through such production and decay channels, one has direct access to the following Higgs self-couplings, thus enabling one to distinguish between a standard and the Supersymmetric version of the above model: lambda_(Hhh) -- which constrains the form of the Higgs potential -- as well as lambda_(W+- H+- h) and lambda_(Z A h) -- which are required by gauge invariance. Unfortunately, such claims cannot be extended to the Minimal Supersymmetric Standard Model, where the extraction of the same signals is impossible.

NEXT-TO-LEADING ORDER QCD CORRECTIONS TO LIGHT HIGGS PAIR PRODUCTION VIA VECTOR BOSON FUSION

We present the NLO QCD corrections for light Higgs pair production via vector boson fusion at the LHC within the CP conserving type II two-Higgs doublet model in the form of a fully flexible parton-level Monte Carlo program. Scale dependences on integrated cross sections and distributions are reduced with QCD K-factors of order unity.

Vector-boson production of light Higgs pairs in 2-Higgs doublet models

At the Large Hadron Collider, we prove the feasibility to detect pair production of the lightest CP-even Higgs boson h of Type II 2-Higgs Doublet Models through qq(') -> qq(')hh (vector-boson fusion). We also show that, through the hh -> 4b decay channel in presence of heavy-flavour tagging, further exploiting forward/backward jet sampling, one has direct access to the lambda Hhh triple Higgs coupling - which constrains the form of the Higgs potential.