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Published December 9, 2016 | Submitted + Published
Journal Article Open

Golden Probe of Electroweak Symmetry Breaking

  • 1. ROR icon California Institute of Technology


The ratio of the Higgs couplings to WW and ZZ pairs, λ_(WZ), is a fundamental parameter in electroweak symmetry breaking as well as a measure of the (approximate) custodial symmetry possessed by the gauge boson mass matrix. We show that Higgs decays to four leptons are sensitive, via tree level/1-loop interference effects, to both the magnitude and, in particular, overall sign of λ_(WZ). Determining this sign requires interference effects, as it is nearly impossible to measure with rate information. Furthermore, simply determining the sign effectively establishes the custodial representation of the Higgs boson. We find that h → 4 ℓ (4 ℓ ≡ 2e2µ; 4e; 4µ) decays have excellent prospects of directly establishing the overall sign at a high luminosity 13 TeV LHC. We also examine the ultimate LHC sensitivity in h → 4 ℓ to the magnitude of λ_(WZ). Our results are independent of other measurements of the Higgs boson couplings and, in particular, largely free of assumptions about the top quark Yukawa couplings which also enter at 1-loop. This makes h → 4 ℓ a unique and independent probe of the electroweak symmetry breaking mechanism and custodial symmetry.

Additional Information

© 2016 The Authors. Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. (Received 5 September 2016; published 9 December 2016) We would like to thank Francisco del Aguila, Adam Falkowski, Heather Logan, Ian Low, Jose Santiago, and Martin Schmaltz for useful discussions. R. V. M. also thanks Fermilab and the Mainz Institute for Theoretical Physics (MITP) for their hospitality and partial support during the completion of this work as well as Tilman Plehn and the participants of the FIRSTRESULTS workshop for useful discussions. The work of Y. C. is supported by the Weston Havens Foundation and DOE Grant No. DE-FG02-92-ER-40701. D. S. is supported in part by the Natural Sciences and Engineering Research Council of Canada (NSERC). R. V. M. is supported by MINECO, under Grant No. FPA2013-47836-C3-2-P.

Attached Files

Published - PhysRevLett.117.241801.pdf

Submitted - 1608.02159v1.pdf


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