A Fermionic Top Partner: Naturalness and the LHC

Abstract

Naturalness demands that the quadratic divergence of the one-loop top contribution to the Higgs mass be cancelled at a scale below 1 TeV. This can be achieved by introducing a fermionic (spin-1/2) top partner, as in, for example, Little Higgs models. In this paper, we study the phenomenology of a simple model realizing this mechanism. We present the current bounds on the model from precision electroweak fits, flavor physics, and direct searches at the LHC. The lower bound on the top partner mass from precision electroweak data is approximately 500 GeV, while the LHC bound with 5/fb of data at sqrt(s)=7 TeV is about 450 GeV. Given these bounds, the model can incorporate a 125 GeV Higgs with minimal fine-tuning of about 20%. We conclude that natural electroweak symmetry breaking with a fermionic top partner remains a viable possibility. We also compute the Higgs decay rates into gauge bosons, and find that significant, potentially observable deviations from the Standard Model predictions may occur.

30 pages, 8 figures, 1 table; v2: Minor changes. Final version to appear in JHEP; v3: References added

References in corpus (9)

• PYTHIA 6.4 Physics and Manual
• -- HATHOR -- HAdronic Top and Heavy quarks crOss section calculatoR
• Combined results of searches for the standard model Higgs boson in pp collisions at sqrt(s) = 7 TeV
• Estimate of BR(B -> X_s gamma) at O(alpha_s^2)
• Light custodians in natural composite Higgs models
• Combined search for the Standard Model Higgs boson using up to 4.9 fb-1 of pp collision data at sqrt(s) = 7 TeV with the ATLAS detector at the LHC
• The Higgs boson from an extended symmetry
• Strong constraints on the rare decays Bs -> mu+ mu- and B0 -> mu+ mu-
• Triangulating an exotic T quark

Cited by in corpus (80)

• Composite Higgses
• A First Top Partner Hunter's Guide
• Model Independent Framework for Searches of Top Partners
• On the Interpretation of a Possible $\sim 750$ GeV Particle Decaying into $\gamma \gamma$
• Light top partners and precision physics
• Physics at the e+ e- Linear Collider
• Higgs Low-Energy Theorem (and its corrections) in Composite Models
• A Higgs Conundrum with Vector Fermions
• Quark flavour observables in the Littlest Higgs model with T-parity after LHC Run 1
• Survey of vector-like fermion extensions of the Standard Model and their phenomenological implications
• Fastlim: a fast LHC limit calculator
• Search for pair and single production of new heavy quarks that decay to a $Z$ boson and a third-generation quark in $pp$ collisions at $\sqrt{s}=8$ TeV with the ATLAS detector
• Light Higgs and Vector-like Quarks without Prejudice
• Pushing Higgs Effective Theory to its Limits
• On the Interpretation of Top Partners Searches
• Search for vector-like $B$ quarks in events with one isolated lepton, missing transverse momentum and jets at $\sqrt{s}=$ 8 TeV with the ATLAS detector
• Search for pair-produced vectorlike B quarks in proton-proton collisions at sqrt(s) = 8 TeV
• Stabilizing Electroweak Vacuum in a Vector-like Fermion Model
• LHC Signatures of Warped-space Vectorlike Quarks
• Alternatives to an Elementary Higgs
• Early discovery of top partners and test of the Higgs nature
• Can the 125 GeV Higgs be the Little Higgs?
• SUSY Stops at a Bump
• Littlest Higgs with T-parity: Status and Prospects
• Little Higgs theory confronted with the LHC Higgs data
• Searching for Dark Photons with Maverick Top Partners
• Interpreting the $W$-mass anomaly in the vectorlike quark models
• Implications of gauge-mediated supersymmetry breaking with vector-like quarks and a ~125 GeV Higgs boson
• Vector-like Bottom Quarks in Composite Higgs Models
• Constraining Top partner and Naturalness at the LHC and TLEP
• Odd Top Partners at the LHC
• Neutrino Masses from Neutral Top Partners
• Top Partners and Higgs Boson Production
• Top Partners Searches and Composite Higgs Models
• New Higgs Production Mechanism in Composite Higgs Models
• Loop Induced Single Top Partner Production and Decay at the LHC
• Top Partner Discovery in the $T\to tZ$ channel at the LHC
• Top Polarization in Stop Production at the LHC
• Single top partner production in the Higgs to diphoton channel in the Littlest Higgs Model with $T$-parity
• Effects from New Colored States and the Higgs Portal on Gluon Fusion and Higgs Decays
• The Excitation of the Global Symmetry-Breaking Vacuum in Composite Higgs Models
• Towards the fate of natural composite Higgs model through single $t^{\prime }$ search at the 8 TeV LHC
• Search for single production of the vector-like top partner at the 14 TeV LHC
• The Natural Composite Higgs
• A Complete Model for R-parity Violation
• Speculations on the W-Mass Measurement at CDF
• Shedding Light on Top Partner at the LHC
• Exotic Top Partners and Little Higgs
• Stop and sbottom search using dileptonic $M_{T2}$ variable and boosted top technique at the LHC
• Probing the flavor violating scalar top quark signal at the LHC
• Higgs Couplings and Naturalness
• Search for single production of the heavy vectorlike $T$ quark with $T\to th$ and $h\to \gamma \gamma$ at the high-luminosity LHC
• Non-minimal Universal Extra Dimensions with Brane Local Terms: The Top Quark Sector
• Higgs couplings and Naturalness in the littlest Higgs model with T-parity at the LHC and TLEP
• The production and decay of the top partner $T$ in the left-right twin higgs model at the ILC and CLIC
• Cancellation in Dark Matter-Nucleon Interactions: the Role of Non-Standard-Model-like Yukawa Couplings
• Exploring maverick top partner decays at the LHC
• Higgs decay to goldstini and its observability at the LHC
• Discovery potential for $T^{\prime }\to tZ$ in the trilepton channel at the LHC
• Heavy vector-like quarks decaying to exotic scalars: a case study with triplets
• Yukawa Corrections to Higgs Production in Top Partner Models
• Looking for a vectorlike B quark at LHC using jet substructure
• LHC signatures of vector-like quarks
• Status and Prospects of the Two-Higgs-Doublet SU(6)/Sp(6) little-Higgs Model and the Alignment Limit
• The fate of the Littlest Higgs Model with T-parity under 13 TeV LHC Data
• Vector Quarks in the Higgs Triplet Model
• Higgs-Precision Constraints on Colored Naturalness
• Left-right twin Higgs model confronted with the latest LHC Higgs data
• Vector-like quarks with a scalar triplet
• Correlating the CDF $W$-boson mass shift with the $b\to s{\ell }^{+}{\ell }^{-}$ anomalies
• Multiple b-jets Reveal Top Super-partners and the 125 GeV Higgs
• Coupling Extraction From Off-Shell Cross-sections
• Minimal Signatures of Naturalness
• Status and Implications of BSM Searches at the LHC
• Combination of searches for singly produced vector-like top quarks in pp collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Emergent 2HDM in LSS Little-Higgs: Musings from Flavor and Electroweak Physics
• Search for pair production of heavy particles decaying to a top quark and a gluon in the lepton+jets final state in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Spin-One Top Partner: Phenomenology
• Vector-like quarks decaying into singly and doubly charged bosons at LHC
• On the implications of positive W mass shift