Vector-like top/bottom quark partners and Higgs physics at the LHC

Abstract

Vector-like quarks (VLQs) that are partners of the heavy top and bottom quarks are predicted in many extensions of the Standard Model (SM). We explore the possibility that these states could explain not only the longstanding anomaly in the forward-backward asymmetry in $b$-quark production at LEP, $A_{\mathrm{FB}}^b$, but also the more recent $\sim 2\sigma$ deviation of the cross section for the associated Higgs production with top quark pairs at the LHC, $\sigma (pp\to t\bar{t}H)$. Introducing three illustrative models for VLQs with different representations under the SM gauge group, we show that the two anomalies can be resolved while satisfying all other theoretical and experimental constraints. In this case, the three different models predict VLQ states in the $1-2$ TeV mass range that can be soon probed at the LHC. In a second step, we discuss the sensitivity on the VLQ masses and couplings that could be obtained by means of a percent level accuracy in the measurement of ratios of partial Higgs decay widths, in particular $\Gamma (H\to \gamma \gamma )/\Gamma (H\to Z{Z}^{\ast })$ and $\Gamma (H\to b\bar{b})/\Gamma (H\to W{W}^{\ast })$. We show that top and bottom VL partners with masses up to $\sim 5$ TeV and exotic VLQs with masses in the $10$ TeV range can be probed at the high-luminosity LHC.

27 pages, 6 figures; v2: added references

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• A custodial symmetry for Zbb
• The global electroweak fit at NNLO and prospects for the LHC and ILC
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• Heavy Quarks Above the Top at the Tevatron
• Constraining extra-fermion(s) from the Higgs boson data
• Vector-like quarks in a composite Higgs model
• Total Width of 125 GeV Higgs Boson
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• Electroweak and QCD corrections to top-pair hadroproduction in association with heavy bosons
• Top Partners and Higgs Boson Production
• Z-peaked excess from heavy gluon decays to vector-like quarks
• Solving the A{FB}^b anomaly in natural composite models
• Precision Higgs coupling measurements at the LHC through ratios of production cross sections
• LHC Implications of the WIMP Miracle and Grand Unification
• Interplay of vector-like top partner multiplets in a realistic mixing set-up

Cited by in corpus (34)

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• Diphoton Excess in Consistent Supersymmetric SU(5) Models with Vector-like Particles
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• Future Collider Signatures of the Possible 750 GeV State
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• A low scale left-right symmetric mirror model
• Pseudoscalar decays to gauge bosons at the LHC and at a future 100 TeV collider
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• Bhabha scattering at ILC250
• Top and bottom partners, Higgs boson on the brane, and the tth signal
• Revisiting Vector-like Quark Model with Enhanced Top Yukawa Coupling
• Complementarity of Resonant Scalar, Vector-Like Quark and Superpartner Searches in Elucidating New Phenomena
• Diboson resonances within a custodially protected warped extra-dimensional scenario
• Rigorous treatment of the ${\mathcal{S}}^1/{\mathbb{Z}}_2$ orbifold model with brane-Higgs couplings
• The Two Scales of New Physics in Loop-Induced Higgs Couplings
• Vector-like Quark Interpretation of Excess in Higgs Signal Strength
• ttH, ttZ and ttW measurements at LHC and top quark compositeness