Search for the lepton-flavour violating decay D<sup>0sup> sp>→ sp>e<sup>±sup>μ<sup>∓sup>
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A search for the lepton-flavour violating decay <span id="mmlsi1" class="mathmlsrc"><span class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0370269316000411&_mathId=si1.gif&_user=111111111&_pii=S0370269316000411&_rdoc=1&_issn=03702693&md5=fc1877ec9ab7d383146f53623195cc45" title="Click to view the MathML source">D<sup>0sup>→e<sup>&plusmn;sup>μ<sup>∓sup>span><span class="mathContainer hidden"><span class="mathCode">si1.gif" overflow="scroll">sup>D0sup>stretchy="false">→sup>e&plusmn;sup>sup>μ∓sup>span>span>span> is made with a dataset corresponding to an integrated luminosity of <span id="mmlsi2" class="mathmlsrc">source" class="mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0370269316000411&_mathId=si2.gif&_user=111111111&_pii=S0370269316000411&_rdoc=1&_issn=03702693&md5=aeceaccfdc386158ce9873498f288901">ss="imgLazyJSB inlineImage" height="14" width="51" alt="View the MathML source" style="margin-top: -5px; vertical-align: middle" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S0370269316000411-si2.gif">script>style="vertical-align:bottom" width="51" alt="View the MathML source" title="View the MathML source" src="http://origin-ars.els-cdn.com/content/image/1-s2.0-S0370269316000411-si2.gif">script><span class="mathContainer hidden"><span class="mathCode">si2.gif" overflow="scroll">3.0space width="0.25em">space>sup>fb&minus;1sup>span>span>span> of proton&ndash;proton collisions at centre-of-mass energies of <span id="mmlsi24" class="mathmlsrc">source" class="mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0370269316000411&_mathId=si24.gif&_user=111111111&_pii=S0370269316000411&_rdoc=1&_issn=03702693&md5=0aeed9fced1f917d344752e5675b6909">ss="imgLazyJSB inlineImage" height="10" width="36" alt="View the MathML source" style="margin-top: -5px; vertical-align: middle" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S0370269316000411-si24.gif">script>style="vertical-align:bottom" width="36" alt="View the MathML source" title="View the MathML source" src="http://origin-ars.els-cdn.com/content/image/1-s2.0-S0370269316000411-si24.gif">script><span class="mathContainer hidden"><span class="mathCode">si24.gif" overflow="scroll">7space width="0.25em">space>TeVspan>span>span> and <span id="mmlsi26" class="mathmlsrc">source" class="mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0370269316000411&_mathId=si26.gif&_user=111111111&_pii=S0370269316000411&_rdoc=1&_issn=03702693&md5=e9c1ace21c4d45fb036fe0c92757049a">ss="imgLazyJSB inlineImage" height="10" width="35" alt="View the MathML source" style="margin-top: -5px; vertical-align: middle" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S0370269316000411-si26.gif">script>style="vertical-align:bottom" width="35" alt="View the MathML source" title="View the MathML source" src="http://origin-ars.els-cdn.com/content/image/1-s2.0-S0370269316000411-si26.gif">script><span class="mathContainer hidden"><span class="mathCode">si26.gif" overflow="scroll">8space width="0.25em">space>TeVspan>span>span>, collected by the LHCb experiment. Candidate <span id="mmlsi5" class="mathmlsrc"><span class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0370269316000411&_mathId=si5.gif&_user=111111111&_pii=S0370269316000411&_rdoc=1&_issn=03702693&md5=f0e2cdc444fe36fa3f696d6a2040a4a6" title="Click to view the MathML source">D<sup>0sup>span><span class="mathContainer hidden"><span class="mathCode">si5.gif" overflow="scroll">sup>D0sup>span>span>span> mesons are selected using the decay <span id="mmlsi27" class="mathmlsrc"><span class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0370269316000411&_mathId=si27.gif&_user=111111111&_pii=S0370269316000411&_rdoc=1&_issn=03702693&md5=35be6e726715a8b901212af5c88ce833" title="Click to view the MathML source">D<sup>⁎+sup>→D<sup>0sup>π<sup>+sup>span><span class="mathContainer hidden"><span class="mathCode">si27.gif" overflow="scroll">sup>D⁎+sup>stretchy="false">→sup>D0sup>sup>π+sup>span>span>span> and the <span id="mmlsi1" class="mathmlsrc"><span class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0370269316000411&_mathId=si1.gif&_user=111111111&_pii=S0370269316000411&_rdoc=1&_issn=03702693&md5=fc1877ec9ab7d383146f53623195cc45" title="Click to view the MathML source">D<sup>0sup>→e<sup>&plusmn;sup>μ<sup>∓sup>span><span class="mathContainer hidden"><span class="mathCode">si1.gif" overflow="scroll">sup>D0sup>stretchy="false">→sup>e&plusmn;sup>sup>μ∓sup>span>span>span> branching fraction is measured using the decay mode <span id="mmlsi28" class="mathmlsrc"><span class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0370269316000411&_mathId=si28.gif&_user=111111111&_pii=S0370269316000411&_rdoc=1&_issn=03702693&md5=50acf2c2ba49be9507581c6d97f5c66b" title="Click to view the MathML source">D<sup>0sup>→K<sup>&minus;sup>π<sup>+sup>span><span class="mathContainer hidden"><span class="mathCode">si28.gif" overflow="scroll">sup>D0sup>stretchy="false">→sup>K&minus;sup>sup>π+sup>span>span>span> as a normalization channel. No significant excess of <span id="mmlsi1" class="mathmlsrc"><span class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0370269316000411&_mathId=si1.gif&_user=111111111&_pii=S0370269316000411&_rdoc=1&_issn=03702693&md5=fc1877ec9ab7d383146f53623195cc45" title="Click to view the MathML source">D<sup>0sup>→e<sup>&plusmn;sup>μ<sup>∓sup>span><span class="mathContainer hidden"><span class="mathCode">si1.gif" overflow="scroll">sup>D0sup>stretchy="false">→sup>e&plusmn;sup>sup>μ∓sup>span>span>span> candidates over the expected background is seen, and a limit is set on the branching fraction, <span id="mmlsi8" class="mathmlsrc"><span class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0370269316000411&_mathId=si8.gif&_user=111111111&_pii=S0370269316000411&_rdoc=1&_issn=03702693&md5=8fe2e966e026ab3053ca20b522e85073" title="Click to view the MathML source">B(D<sup>0sup>→e<sup>&plusmn;sup>μ<sup>∓sup>)<1.3&times;10<sup>&minus;8sup>span><span class="mathContainer hidden"><span class="mathCode">si8.gif" overflow="scroll">script">Bstretchy="false">(sup>D0sup>stretchy="false">→sup>e&plusmn;sup>sup>μ∓sup>stretchy="false">)<1.3&times;sup>10&minus;8sup>span>span>span>, at 90% confidence level. This is an order of magnitude lower than the previous limit and it further constrains the parameter space in some leptoquark models and in supersymmetric models with R-parity violation.

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