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Published September 2015 | Published + Submitted
Journal Article Open

New Opportunities in h → 4ℓ


The Higgs decay h → 4ℓ has played an important role in discovering the Higgs and measuring its mass thanks to low background and excellent resolution. Current cuts in this channel have been optimized for Higgs discovery via the dominant tree level ZZ contribution arising from electroweak symmetry breaking. Going forward, one of the primary objectives of this sensitive channel will be to probe other Higgs couplings and search for new physics on top of the tree level ZZ `back-ground'. Thanks to interference between these small couplings and the large tree level contribution to ZZ, the h → 4ℓ decay is uniquely capable of probing the magnitude and CP phases of the Higgs couplings to and Z as well as, to a lesser extent, ZZ couplings arising from higher dimensional operators. With this in mind we examine how much relaxing current cuts can enhance the sensitivity while also accounting for the dominant non-Higgs continuum qq → 4ℓ background. We find the largest enhancement in sensitivity for the hZy couplings (≳ 100%) followed by hyy (≳ 40%) and less so for the higher dimensional hZZ couplings (a few percent). With these enhancements, we show that couplings of order Standard Model values for hyy may optimistically be probed by end of Run-II at the LHC while for hZy perhaps towards the end of a high luminosity LHC. Thus an appropriately optimized h → 4ℓ analysis can complement direct decays of the Higgs to on-shell and Z pairs giving a unique opportunity to directly access the CP properties of these couplings.

Additional Information

Open Access, © The Authors. Article funded by SCOAP3. 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. Received: April 4, 2015. Revised: August 27, 2015. Accepted: September 3, 2015. Published: September 28, 2015. We thank Joe Lykken and Maria Spiropulu for providing us with the resources necessary to complete this study and Adam Falkowski for useful comments on the manuscript. We also thank Ian Low, Javi Serra, and Daniel Stolarski for helpful discussions. R.V.M. is supported by the ERC Advanced Grant Higgs@LHC. Fermilab is operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. Y.C. is supported by the Weston Havens Foundation and DOE grant No. DE-FG02-92-ER-40701. This work is also sponsored in part by the DOE grant No. DE-FG02-91ER40684 and used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number OCI-1053575.

Attached Files

Published - art_10.1007_JHEP09_2015_185.pdf

Submitted - 1503.05855v1.pdf


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August 20, 2023
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