Uncovering the relation of a scalar resonance to the Higgs boson

AbstractWe show that the presence of a lightish scalar resonance, $$\sigma $$σ, that mixes with the composite Goldstone–Higgs boson can relax the typical bounds found in this class of models. This mechanism, inbred in models with a walking dynamics above the condensation scale, allows for a low compositeness scale $$f \gtrsim 400$$f≳400 GeV, corresponding to a misalignment angle $$s_\theta \lesssim 0.6$$sθ≲0.6, contrary to the common lore of a smaller angle. According to recent lattice results, the light $$\sigma $$σ emerges thanks to a near-conformal phase above the condensation scale, consistent to the requirements from flavour physics. We study this effect in a general way, showing that it appears in all cosets emerging from an underlying gauge-fermion dynamics, in the presence of top partial compositeness. The scenario is testable both on the Lattice and experimentally, as it requires the presence of a second broad Higgs-like resonance, below 1 TeV, that can be revealed at the LHC in the ZZ and $$t\bar{t}$$tt¯ channels.

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Reconstruction and identification of boosted di-τ systems in a search for Higgs boson pairs using 13 TeV proton-proton collision data in ATLAS

Journal of High Energy Physics ◽

10.1007/jhep11(2020)163 ◽

2020 ◽

Vol 2020 (11) ◽

Author(s):

G. Aad ◽

◽

B. Abbott ◽

D. C. Abbott ◽

A. Abed Abud ◽

...

Keyword(s):

Higgs Boson ◽

Hadron Collider ◽

Gluon Fusion ◽

Mass Range ◽

Proton Collision ◽

Final State ◽

Proton Proton ◽

Scalar Resonance ◽

Proton Proton Collision ◽

A New Technique

Abstract In this paper, a new technique for reconstructing and identifying hadronically decaying τ+τ− pairs with a large Lorentz boost, referred to as the di-τ tagger, is developed and used for the first time in the ATLAS experiment at the Large Hadron Collider. A benchmark di-τ tagging selection is employed in the search for resonant Higgs boson pair production, where one Higgs boson decays into a boosted $$ b\overline{b} $$ b b ¯ pair and the other into a boosted τ+τ− pair, with two hadronically decaying τ-leptons in the final state. Using 139 fb−1 of proton-proton collision data recorded at a centre-of-mass energy of 13 TeV, the efficiency of the di-τ tagger is determined and the background with quark- or gluon-initiated jets misidentified as di-τ objects is estimated. The search for a heavy, narrow, scalar resonance produced via gluon-gluon fusion and decaying into two Higgs bosons is carried out in the mass range 1–3 TeV using the same dataset. No deviations from the Standard Model predictions are observed, and 95% confidence-level exclusion limits are set on this model.

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