Golden probe of electroweak symmetry breaking
The ratio of the Higgs couplings to $WW$ and $ZZ$ pairs, $$\lambda_{WZ}$$, 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/1loop interference effects, to both the magnitude and, in particular, overall sign of $$\lambda_{WZ}$$. 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 $$h\to4\ell$$ ($$4\ell \equiv 2e2\mu, 4e, 4\mu$$) 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 $$h\to4\ell$$ to the magnitude of $$\lambda_{WZ}$$. 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 1loop. Furthermore, this makes $$h\to4\ell$$ a unique and independent probe of the electroweak symmetry breaking mechanism and custodial symmetry.
 Authors:

^{[1]};
^{[2]};
^{[3]};
^{[4]};
^{[5]}
 European Organization for Nuclear Research (CERN), Geneva (Switzerland); California Inst. of Technology (CalTech), Pasadena, CA (United States)
 Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
 California Inst. of Technology (CalTech), Pasadena, CA (United States)
 Carleton Univ., Ottawa, ON (Canada)
 Univ. de Granada, Granada (Spain)
 Publication Date:
 Report Number(s):
 UGFT32216; CAFPE19216; FERMILABPUB16304PPD; arXiv:1608.02159
Journal ID: ISSN 00319007; PRLTAO; 1479943
 Grant/Contract Number:
 AC0207CH11359; FG0292ER40701
 Type:
 Published Article
 Journal Name:
 Physical Review Letters
 Additional Journal Information:
 Journal Volume: 117; Journal Issue: 24; Journal ID: ISSN 00319007
 Publisher:
 American Physical Society (APS)
 Research Org:
 Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
 Sponsoring Org:
 USDOE Office of Science (SC), High Energy Physics (HEP) (SC25)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
 OSTI Identifier:
 1335055
 Alternate Identifier(s):
 OSTI ID: 1335647
Chen, Yi, Lykken, Joe, Spiropulu, Maria, Stolarski, Daniel, and VegaMorales, Roberto. Golden probe of electroweak symmetry breaking. United States: N. p.,
Web. doi:10.1103/PhysRevLett.117.241801.
Chen, Yi, Lykken, Joe, Spiropulu, Maria, Stolarski, Daniel, & VegaMorales, Roberto. Golden probe of electroweak symmetry breaking. United States. doi:10.1103/PhysRevLett.117.241801.
Chen, Yi, Lykken, Joe, Spiropulu, Maria, Stolarski, Daniel, and VegaMorales, Roberto. 2016.
"Golden probe of electroweak symmetry breaking". United States.
doi:10.1103/PhysRevLett.117.241801.
@article{osti_1335055,
title = {Golden probe of electroweak symmetry breaking},
author = {Chen, Yi and Lykken, Joe and Spiropulu, Maria and Stolarski, Daniel and VegaMorales, Roberto},
abstractNote = {The ratio of the Higgs couplings to $WW$ and $ZZ$ pairs, $\lambda_{WZ}$, 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/1loop interference effects, to both the magnitude and, in particular, overall sign of $\lambda_{WZ}$. 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 $h\to4\ell$ ($4\ell \equiv 2e2\mu, 4e, 4\mu$) 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 $h\to4\ell$ to the magnitude of $\lambda_{WZ}$. 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 1loop. Furthermore, this makes $h\to4\ell$ a unique and independent probe of the electroweak symmetry breaking mechanism and custodial symmetry.},
doi = {10.1103/PhysRevLett.117.241801},
journal = {Physical Review Letters},
number = 24,
volume = 117,
place = {United States},
year = {2016},
month = {12}
}