Search for a heavy Higgs boson decaying into two lighter Higgs bosons in the ττbb final state at 13 TeV

A search for a heavy Higgs boson H decaying into the observed Higgs boson h with a mass of 125 GeV and another Higgs boson hS is presented. The h and hS bosons are required to decay into a pair of tau leptons and a pair of b quarks, respectively. The search uses a sample of proton-proton collisions collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 137 fb−1. Mass ranges of 240–3000 GeV for mH and 60–2800 GeV for $$ {m}_{{\mathrm{h}}_{\mathrm{S}}} $$ m h S are explored in the search. No signal has been observed. Model independent 95% confidence level upper limits on the product of the production cross section and the branching fractions of the signal process are set with a sensitivity ranging from 125 fb (for mH = 240 GeV) to 2.7 fb (for mH = 1000 GeV). These limits are compared to maximally allowed products of the production cross section and the branching fractions of the signal process in the next-to-minimal supersymmetric extension of the standard model.

Integrating out heavy fields in the path integral using the background-field method: general formalism

Building on an older method used to derive non-decoupling effects of a heavy Higgs boson in the Standard Model, we describe a general procedure to integrate out heavy fields in the path integral. The derivation of the corresponding effective Lagrangian including the one-loop contributions of the heavy particle(s) is particularly transparent, flexible, and algorithmic. The background-field formalism allows for a clear separation of tree-level and one-loop effects involving the heavy fields. Using expansion by regions the one-loop effects are further split into contributions from large and small momentum modes. The former are contained in Wilson coefficients of effective operators, the latter are reproduced by one-loop diagrams involving effective tree-level couplings. The method is illustrated by calculating potential non-decoupling effects of a heavy Higgs boson in a singlet Higgs extension of the Standard Model. In particular, we work in a field basis corresponding to mass eigenstates and properly take into account non-vanishing mixing between the two Higgs fields of the model. We also show that a proper choice of renormalization scheme for the non-standard sector of the underlying full theory is crucial for the construction of a consistent effective field theory.

Search for a heavy Higgs boson decaying into a Z boson and another heavy Higgs boson in the $$\ell \ell bb$$ and $$\ell \ell WW$$ final states in pp collisions at $$\sqrt{s}=13$$ $$\text {TeV}$$ with the ATLAS detector

A search for a heavy neutral Higgs boson, A, decaying into a Z boson and another heavy Higgs boson, H, is performed using a data sample corresponding to an integrated luminosity of 139 fb$$^{-1}$$ - 1 from proton–proton collisions at $$\sqrt{s} = 13$$ s = 13 $$\text {TeV}$$ TeV recorded by the ATLAS detector at the LHC. The search considers the Z boson decaying into electrons or muons and the H boson into a pair of b-quarks or W bosons. The mass range considered is 230–800 $$\text {GeV}$$ GeV for the A boson and 130–700 $$\text {GeV}$$ GeV for the H boson. The data are in good agreement with the background predicted by the Standard Model, and therefore 95% confidence-level upper limits for $$\sigma \times B(A\rightarrow ZH)\times B(H\rightarrow bb \; \text {or} \; H \rightarrow WW)$$ σ × B ( A → Z H ) × B ( H → b b or H → W W ) are set. The upper limits are in the range 0.0062–0.380 pb for the $$H\rightarrow bb$$ H → b b channel and in the range 0.023–8.9 pb for the $$H\rightarrow WW$$ H → W W channel. An interpretation of the results in the context of two-Higgs-doublet models is also given.

Probing electroweak baryogenesis induced by extra bottom Yukawa coupling via EDMs and collider signatures

We study the prospect of probing electroweak baryogenesis driven by an extra bottom Yukawa coupling ρbb in a general two Higgs doublet model via electric dipole moment (EDM) measurements and at the collider experiments. The parameter space receives meaningful constraints from 125 GeV Higgs h boson signal strength measurements as well as several heavy Higgs boson searches at the Large Hadron Collider (LHC). In addition, we show that the asymmetry of the CP asymmetry of inclusive B → Xsγ decay would provide complementary probe. A discovery is possible at the LHC via bg → bA → bZh process if |ρbb| ∼ 0.15 and 250 GeV≲ mA ≲ 350 GeV, where A is CP odd scalar. For mA> 2mt threshold, where mt is the top quark mass, one may also discover bg → bA →$$ bt\overline{t} $$ bt t ¯ at the high luminosity LHC run if an extra top Yukawa coupling |ρtt| ∼ 0.5, though it may suffer from systematic uncertainties. For completeness we study gg →$$ t\overline{t}A $$ t t ¯ A →$$ t\overline{t}b\overline{b} $$ t t ¯ b b ¯ but find it not promising.