Abstract
Many new physics models predict sizable modifications to the SM \( Zb\overline{b} \) couplings, while the corresponding measurements at LEP and SLC exhibit some discrepancy with the SM predictions. After updating the current results on the \( Zb\overline{b} \) coupling constraints from global fits, we list the observables that are most important for improving the \( Zb\overline{b} \) coupling constraints and estimate the expected precision reach of three proposed future e + e − colliders, CEPC, ILC and FCC-ee. We consider both the case that the results are SM-like and the one that the \( Zb\overline{b} \) couplings deviate significantly from the SM predictions. We show that, if we assume the value of the \( Zb\overline{b} \) couplings to be within 68% CL of the current measurements, any one of the three colliders will be able to rule out the SM with more than 99.9999% CL (5σ). We study the implications of the improved \( Zb\overline{b} \) coupling constraints on new physics models, and point out their complementarity with the constraints from the direct search of new physics particles at the LHC, as well as with Higgs precision measurements. Our results provide a further motivation for the construction of future e + e − colliders.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
H. Baer et al., The International Linear Collider Technical Design Report — Volume 2: Physics, arXiv:1306.6352 [INSPIRE].
TLEP Design Study Working Group collaboration, M. Bicer et al., First Look at the Physics Case of TLEP, JHEP 01 (2014) 164 [arXiv:1308.6176] [INSPIRE].
M. Ahmad et al., CEPC-SPPC Preliminary Conceptual Design Report, Volume I: Physics and Detector, (2015), http://cepc.ihep.ac.cn/preCDR/volume.html.
M. Baak et al., Working Group Report: Precision Study of Electroweak Interactions, arXiv:1310.6708 [INSPIRE].
J. Fan, M. Reece and L.-T. Wang, Possible Futures of Electroweak Precision: ILC, FCC-ee and CEPC, JHEP 09 (2015) 196 [arXiv:1411.1054] [INSPIRE].
J. Fan, M. Reece and L.-T. Wang, Precision Natural SUSY at CEPC, FCC-ee and ILC, JHEP 08 (2015) 152 [arXiv:1412.3107] [INSPIRE].
D. Curtin, R. Essig, S. Gori and J. Shelton, Illuminating Dark Photons with High-Energy Colliders, JHEP 02 (2015) 157 [arXiv:1412.0018] [INSPIRE].
M.E. Peskin and T. Takeuchi, Estimation of oblique electroweak corrections, Phys. Rev. D 46 (1992) 381 [INSPIRE].
R.D. Peccei, S. Peris and X. Zhang, Nonstandard couplings of the top quark and precision measurements of the electroweak theory, Nucl. Phys. B 349 (1991) 305 [INSPIRE].
K. Agashe, R. Contino, L. Da Rold and A. Pomarol, A custodial symmetry for \( Zb\overline{b} \), Phys. Lett. B 641 (2006) 62 [hep-ph/0605341] [INSPIRE].
H.E. Haber and H.E. Logan, Radiative corrections to the \( Zb\overline{b} \) vertex and constraints on extended Higgs sectors, Phys. Rev. D 62 (2000) 015011 [hep-ph/9909335] [INSPIRE].
ALEPH, DELPHI, L3, OPAL, SLD collaborations, the LEP Electroweak Working Group, the SLD Electroweak Group, the SLD Heavy Flavour Group, S. Schael et al., Precision electroweak measurements on the Z resonance, Phys. Rept. 427 (2006) 257 [hep-ex/0509008] [INSPIRE].
A. Freitas and Y.-C. Huang, Electroweak two-loop corrections to \( si{n}^2{\theta}_{\mathrm{eff}}^{b\overline{b}} \) and R b using numerical Mellin-Barnes integrals, JHEP 08 (2012) 050 [Erratum ibid. 1305 (2013) 074] [arXiv:1205.0299] [INSPIRE].
Gfitter Group collaboration, M. Baak et al., The global electroweak fit at NNLO and prospects for the LHC and ILC, Eur. Phys. J. C 74 (2014) 3046 [arXiv:1407.3792] [INSPIRE].
A. Freitas, Higher-order electroweak corrections to the partial widths and branching ratios of the Z boson, JHEP 04 (2014) 070 [arXiv:1401.2447] [INSPIRE].
B. Batell, S. Gori and L.-T. Wang, Higgs Couplings and Precision Electroweak Data, JHEP 01 (2013) 139 [arXiv:1209.6382] [INSPIRE].
M. Ciuchini, E. Franco, S. Mishima and L. Silvestrini, Electroweak Precision Observables, New Physics and the Nature of a 126 GeV Higgs Boson, JHEP 08 (2013) 106 [arXiv:1306.4644] [INSPIRE].
H. Flacher, M. Goebel, J. Haller, A. Hocker, K. Monig and J. Stelzer, Revisiting the Global Electroweak Fit of the Standard Model and Beyond with Gfitter, Eur. Phys. J. C 60 (2009) 543 [Erratum ibid. C 71 (2011) 1718] [arXiv:0811.0009] [INSPIRE].
A. Pomarol and F. Riva, Towards the Ultimate SM Fit to Close in on Higgs Physics, JHEP 01 (2014) 151 [arXiv:1308.2803] [INSPIRE].
J. Ellis, V. Sanz and T. You, The Effective Standard Model after LHC Run I, JHEP 03 (2015) 157 [arXiv:1410.7703] [INSPIRE].
A. Falkowski and F. Riva, Model-independent precision constraints on dimension-6 operators, JHEP 02 (2015) 039 [arXiv:1411.0669] [INSPIRE].
L. Berthier and M. Trott, Towards consistent Electroweak Precision Data constraints in the SMEFT, JHEP 05 (2015) 024 [arXiv:1502.02570] [INSPIRE].
L. Berthier and M. Trott, Consistent constraints on the Standard Model Effective Field Theory, JHEP 02 (2016) 069 [arXiv:1508.05060] [INSPIRE].
Particle Data Group collaboration, K.A. Olive et al., Review of Particle Physics, Chin. Phys. C 38 (2014) 090001 [INSPIRE].
ATLAS, CDF, CMS, D0 collaborations, First combination of Tevatron and LHC measurements of the top-quark mass, arXiv:1403.4427 [INSPIRE].
ATLAS collaboration, Measurement of the Higgs boson mass from the H → γγ and H →ZZ * →4ℓ channels with the ATLAS detector using 25 fb −1 of pp collision data, Phys. Rev. D 90 (2014) 052004 [arXiv:1406.3827] [INSPIRE].
CMS collaboration, Precise determination of the mass of the Higgs boson and studies of the compatibility of its couplings with the standard model, CMS-PAS-HIG-14-009.
M. Davier, A. Hoecker, B. Malaescu and Z. Zhang, Reevaluation of the Hadronic Contributions to the Muon g − 2 and to α(M 2 Z ), Eur. Phys. J. C 71 (2011) 1515 [Erratum ibid. C 72 (2012) 1874] [arXiv:1010.4180] [INSPIRE].
C.W. Murphy, Bottom-Quark Forward-Backward and Charge Asymmetries at Hadron Colliders, Phys. Rev. D 92 (2015) 054003 [arXiv:1504.02493] [INSPIRE].
A. Pich, Review of α s determinations, PoS(Confinement X)022 [arXiv:1303.2262] [INSPIRE].
M. Ciuchini, E. Franco, S. Mishima, M. Pierini, L. Reina and L. Silvestrini, Update of the electroweak precision fit, interplay with Higgs-boson signal strengths and model-independent constraints on new physics, arXiv:1410.6940 [INSPIRE].
D. Choudhury, T.M.P. Tait and C.E.M. Wagner, Beautiful mirrors and precision electroweak data, Phys. Rev. D 65 (2002) 053002 [hep-ph/0109097] [INSPIRE].
ATLAS collaboration, Search for charged Higgs bosons decaying via H ± → τ ± ν in fully hadronic final states using pp collision data at \( \sqrt{s}=8 \) TeV with the ATLAS detector, JHEP 03 (2015) 088 [arXiv:1412.6663] [INSPIRE].
CMS collaboration, Search for a heavy charged Higgs boson in proton-proton collisions at \( \sqrt{s}=8 \) TeV with the CMS detector, CMS-PAS-HIG-13-026.
N. Craig, F. D’Eramo, P. Draper, S. Thomas and H. Zhang, The Hunt for the Rest of the Higgs Bosons, JHEP 06 (2015) 137 [arXiv:1504.04630] [INSPIRE].
L. Da Rold, Solving the A b FB anomaly in natural composite models, JHEP 02 (2011) 034 [arXiv:1009.2392] [INSPIRE].
C. Grojean, O. Matsedonskyi and G. Panico, Light top partners and precision physics, JHEP 10 (2013) 160 [arXiv:1306.4655] [INSPIRE].
G. Panico and A. Wulzer, The Composite Nambu-Goldstone Higgs, Lect. Notes Phys. 913 (2016) 1 [arXiv:1506.01961] [INSPIRE].
O. Matsedonskyi, G. Panico and A. Wulzer, Light Top Partners for a Light Composite Higgs, JHEP 01 (2013) 164 [arXiv:1204.6333] [INSPIRE].
A. Thamm, R. Torre and A. Wulzer, Future tests of Higgs compositeness: direct vs indirect, JHEP 07 (2015) 100 [arXiv:1502.01701] [INSPIRE].
D. Barducci, S. De Curtis, S. Moretti and G.M. Pruna, Top pair production at a future e + e − machine in a composite Higgs scenario, JHEP 08 (2015) 127 [arXiv:1504.05407] [INSPIRE].
J.A. Aguilar-Saavedra, R. Benbrik, S. Heinemeyer and M. Pérez-Victoria, Handbook of vectorlike quarks: Mixing and single production, Phys. Rev. D 88 (2013) 094010 [arXiv:1306.0572] [INSPIRE].
D.E. Morrissey and C.E.M. Wagner, Beautiful mirrors, unification of couplings and collider phenomenology, Phys. Rev. D 69 (2004) 053001 [hep-ph/0308001] [INSPIRE].
K. Kumar, W. Shepherd, T.M.P. Tait and R. Vega-Morales, Beautiful Mirrors at the LHC, JHEP 08 (2010) 052 [arXiv:1004.4895] [INSPIRE].
CMS collaboration, Search for vector-like quarks in final states with a single lepton and jets in pp collisions at \( \sqrt{s}=8 \) TeV, CMS-PAS-B2G-12-017.
CMS collaboration, Search for pair-produced vector-like quarks of charge -1/3 decaying to bH using boosted Higgs jet-tagging in pp collisions at \( \sqrt{s}=8 \) TeV, CMS-PAS-B2G-14-001.
E. Álvarez, L. Da Rold and J.I. Sanchez Vietto, Single production of an exotic bottom partner at LHC, JHEP 02 (2014) 010 [arXiv:1311.2077] [INSPIRE].
G. Salam and A. Weiler, Collider Reach (β), http://collider-reach.web.cern.ch/collider-reach/.
R. Dermisek, S.-G. Kim and A. Raval, New Vector Boson Near the Z-pole and the Puzzle in Precision Electroweak Data, Phys. Rev. D 84 (2011) 035006 [arXiv:1105.0773] [INSPIRE].
R. Dermisek, S.-G. Kim and A. Raval, Z’ near the Z-pole, Phys. Rev. D 85 (2012) 075022 [arXiv:1201.0315] [INSPIRE].
M. Awramik, M. Czakon, A. Freitas and B.A. Kniehl, Two-loop electroweak fermionic corrections to \( { \sin}^2{\theta}_{\mathrm{eff}}^{b\overline{b}} \), Nucl. Phys. B 813 (2009) 174 [arXiv:0811.1364] [INSPIRE].
Open Access
This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.
Author information
Authors and Affiliations
Corresponding author
Additional information
ArXiv ePrint: 1508.07010
Rights and permissions
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0), which permits use, duplication, adaptation, distribution, and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
About this article
Cite this article
Gori, S., Gu, J. & Wang, LT. The \( Zb\overline{b} \) couplings at future e + e − colliders. J. High Energ. Phys. 2016, 62 (2016). https://doi.org/10.1007/JHEP04(2016)062
Received:
Revised:
Accepted:
Published:
DOI: https://doi.org/10.1007/JHEP04(2016)062