A study of the decay
rc">rmulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0370269316301022&_mathId=si1.gif&_user=111111111&_pii=S0370269316301022&_rdoc=1&_issn=03702693&md5=a27d90cd9ed1c8a9305ee68cb10567d6" title="Click to view the MathML source">D0→K−π+μ+μ−r hidden"> is pe
rfo
rmed using data collected by the LHCb detecto
r in p
roton–p
roton collisions at a cent
re-of-mass ene
rgy of 8 TeV, co
rresponding to an integ
rated luminosity of
rc">rmulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0370269316301022&_mathId=si2.gif&_user=111111111&_pii=S0370269316301022&_rdoc=1&_issn=03702693&md5=aa553350039047030cfe0c9c588b103c" title="Click to view the MathML source">2.0 fb−1r hidden">. Decay candidates with muon pai
rs that have an inva
riant mass in the
range
rc">rmulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0370269316301022&_mathId=si102.gif&_user=111111111&_pii=S0370269316301022&_rdoc=1&_issn=03702693&md5=9ca79b3c364a17f07386b953b9201081" title="Click to view the MathML source">675–875 MeV/c2r hidden"> a
re conside
red. This
region is dominated by the
rc">rmulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0370269316301022&_mathId=si11.gif&_user=111111111&_pii=S0370269316301022&_rdoc=1&_issn=03702693&md5=ed6c8ea4c95c2a6afc807fff99e1cc17" title="Click to view the MathML source">ρ0r hidden"> and
ω resonances. The b
ranching f
raction in this
range is measu
red to be
This is the fi
rst obse
rvation of the decay
rc">rmulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0370269316301022&_mathId=si1.gif&_user=111111111&_pii=S0370269316301022&_rdoc=1&_issn=03702693&md5=a27d90cd9ed1c8a9305ee68cb10567d6" title="Click to view the MathML source">D0→K−π+μ+μ−r hidden">. Its b
ranching f
raction is consistent with the value expected in the Standa
rd Model.