Measurement of the Higgs boson mass and width using the four-lepton final state in proton-proton collisions at s=13 TeV

Abstract

A measurement of the Higgs boson mass and width via its decay to two <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>Z</a:mi></a:math> bosons is presented. Proton-proton collision data collected by the CMS experiment, corresponding to an integrated luminosity of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mn>138</c:mn><c:mtext> </c:mtext><c:mtext> </c:mtext><c:msup><c:mi>fb</c:mi><c:mrow><c:mo>−</c:mo><c:mn>1</c:mn></c:mrow></c:msup></c:math> at a center-of-mass energy of 13 TeV, is used. The invariant mass distribution of four leptons in the on-shell Higgs boson decay is used to measure its mass and constrain its width. This yields the most precise single measurement of the Higgs boson mass to date, <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mn>125.04</e:mn><e:mo>±</e:mo><e:mn>0.12</e:mn><e:mtext> </e:mtext><e:mtext> </e:mtext><e:mi>GeV</e:mi></e:math>, and an upper limit on the width <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:msub><g:mi mathvariant="normal">Γ</g:mi><g:mi>H</g:mi></g:msub><g:mo>&lt;</g:mo><g:mn>330</g:mn><g:mtext> </g:mtext><g:mtext> </g:mtext><g:mi>MeV</g:mi></g:math> at 95% confidence level. A combination of the on- and off-shell Higgs boson production decaying to four leptons is used to determine the Higgs boson width, assuming that no new virtual particles affect the production, a premise that is tested by adding new heavy particles in the gluon fusion loop model. This result is combined with a previous CMS analysis of the off-shell Higgs boson production with decay to two leptons and two neutrinos, giving a measured Higgs boson width of <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"><j:msubsup><j:mn>3.0</j:mn><j:mrow><j:mo>−</j:mo><j:mn>1.5</j:mn></j:mrow><j:mrow><j:mo>+</j:mo><j:mn>2.0</j:mn></j:mrow></j:msubsup><j:mtext> </j:mtext><j:mtext> </j:mtext><j:mi>MeV</j:mi></j:math>, in agreement with the standard model prediction of 4.1 MeV. The strength of the off-shell Higgs boson production is also reported. The scenario of no off-shell Higgs boson production is excluded at a confidence level corresponding to 3.8 standard deviations.