Determination of the Relative Sign of the Higgs Boson Couplings to W and Z Bosons Using WH Production via Vector-Boson Fusion with the ATLAS Detector

The associated production of Higgs and <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>W</a:mi></a:math> bosons via vector-boson fusion is highly sensitive to the relative sign of the Higgs boson couplings to <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>W</c:mi></c:math> and <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mi>Z</e:mi></e:math> bosons. In this Letter, two searches for this process are presented, using <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mrow><g:mn>140</g:mn><g:mtext> </g:mtext><g:mtext> </g:mtext><g:msup><g:mrow><g:mi>fb</g:mi></g:mrow><g:mrow><g:mo>−</g:mo><g:mn>1</g:mn></g:mrow></g:msup></g:mrow></g:math> of proton-proton collision data at <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mrow><i:msqrt><i:mrow><i:mi>s</i:mi></i:mrow></i:msqrt><i:mo>=</i:mo><i:mn>13</i:mn><i:mtext> </i:mtext><i:mtext> </i:mtext><i:mi>TeV</i:mi></i:mrow></i:math> recorded by the ATLAS detector at the LHC. The first search targets scenarios with opposite-sign couplings of the <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mi>W</k:mi></k:math> and <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mi>Z</m:mi></m:math> bosons to the Higgs boson, while the second targets standard model-like scenarios with same-sign couplings. Both analyses consider Higgs boson decays into a pair of <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mi>b</o:mi></o:math> quarks and <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"><q:mi>W</q:mi></q:math> boson decays with an electron or muon. The data exclude the opposite-sign coupling hypothesis with a significance beyond <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" display="inline"><s:mn>5</s:mn><s:mi>σ</s:mi></s:math>, and the observed (expected) upper limit set on the cross section for vector-boson fusion <u:math xmlns:u="http://www.w3.org/1998/Math/MathML" display="inline"><u:mi>W</u:mi><u:mi>H</u:mi></u:math> production is 9.0 (8.7) times the standard model value at 95% confidence level.