Interpretation of LHC excesses in ditop and ditau channels as a 400-GeV pseudoscalar resonance

Abstract

Since the discovery in 2012 of the Higgs boson at the LHC, as the last missing piece of the Standard Model of particle physics, any hint of new physics has been intensively searched for, with no confirmation to date. There are however slight deviations from the SM that are worth investigating. The CMS collaboration has reported, in a search for heavy resonances decaying in $t\bar{t}$ with a 13-TeV center-of-mass energy and a luminosity of 35.9 fb${}^{-1}$, deviations from the SM predictions at the 3.5$\sigma$ level locally (1.9$\sigma$ after the look-elsewhere effect). In addition, in the ditau final state search performed by the ATLAS collaboration at $\sqrt{s}=13$ TeV and $\mathcal{L}=139$ fb${}^{-1}$, deviations from the SM at the 2$\sigma$ level have been also observed. Interestingly, both slight excesses are compatible with a new pseudoscalar boson with a mass around 400 GeV that couples at least to fermions of the third generation and gluons. Starting from a purely phenomenological perspective, we inspect the possibility that a 400-GeV pseudoscalar can account for these deviations and at the same time satisfy the constraints on the rest of the channels that it gives contributions to and that are analyzed by the ATLAS and CMS experiments. After obtaining the range of effective couplings compatible with all experimental measurements, we study the gauge invariant UV completions that can give rise to this type of pseudoscalar resonance, which can be accommodated in an $SO(6)/SO(5)$ model with consistency at the 1$\sigma$ level and in a $SO(5)\times U(1{)}_P\times U(1{)}_X/SO(4)\times U(1{)}_X$ at the 2$\sigma$ level, while exceedingly large quartic couplings would be necessary to account for it in a general two Higgs doublet model.

arXiv comment24 pages, 3 figures, 2 tables; matches version published in JHEP

References in corpus (35)

• Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC
• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• The Minimal Composite Higgs Model
• Higgs as a Holographic Pseudo-Goldstone Boson
• A custodial symmetry for Zbb
• Model-independent constraints on Delta F=2 operators and the scale of New Physics
• Flavor Structure of Warped Extra Dimension Models
• The Composite Nambu-Goldstone Higgs
• The Flavor of the Composite Pseudo-Goldstone Higgs
• Beyond the Minimal Composite Higgs Model
• What is the gamma gamma resonance at 750 GeV?
• The Other Natural Two Higgs Doublet Model
• The Minimal Composite Higgs Model and Electroweak Precision Tests
• Search for heavy Higgs bosons decaying into two tau leptons with the ATLAS detector using $pp$ collisions at $\sqrt{s}=13$ TeV
• Holography for fermions
• Search for Scalar Diphoton Resonances in the Mass Range $65-600$ GeV with the ATLAS Detector in $pp$ Collision Data at $\sqrt{s}$ = 8 $TeV$
• A minimal set of top-Higgs anomalous couplings
• Search for diphoton resonances in the mass range from 150 to 850 GeV in pp collisions at sqrt(s) = 8 TeV
• Search for new phenomena in high-mass diphoton final states using 37 fb${}^{-1}$ of proton-proton collisions collected at $\sqrt{s}=13$ TeV with the ATLAS detector
• Composite Higgs-Mediated FCNC
• Search for a new scalar resonance decaying to a pair of Z bosons in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Search for heavy resonances decaying into a $W$ or $Z$ boson and a Higgs boson in final states with leptons and $b$-jets in 36 fb${}^{-1}$ of $\sqrt{s}=13$ TeV $pp$ collisions with the ATLAS detector
• Weak Interactions in Top-Quark Pair Production at Hadron Colliders: An Update
• Flavor hierarchies from dynamical scales
• Possible indications for new Higgs bosons in the reach of the LHC: N2HDM and NMSSM interpretations
• Search for a heavy pseudoscalar boson decaying to a Z and a Higgs boson at $\sqrt{s}=$ 13 TeV
• Matched predictions for the $b\bar{b}H$ cross section at the 13 TeV LHC
• Higgs bosons with large couplings to light quarks
• Minimally extended SILH
• Search for beyond the standard model Higgs bosons decaying into a $\mathrm{b}\overline{\mathrm{b}}$ pair in pp collisions at $\sqrt{s}=$ 13 TeV
• On the Structure of Anomalous Composite Higgs Models
• Anomaly Holography, the Wess-Zumino-Witten Term, and Electroweak Symmetry Breaking
• Anomaly Holography
• Topological terms in Composite Higgs Models
• Evidences for a pseudo scalar resonance at 400 GeV Possible interpretations