Mu to E Gamma

<h2 id="results">Results</h2>
<p>In May 2016 the MEG experiment published the world's leading upper limit on the branching ratio of this decay:
</p>

B
        
        (
        
          μ
          
            +
          
        
        →
        
          e
          
            +
          
        
        γ
        )
        <
        4.2
        ×
        
          10
          
            −
            13
          
        
      
    
    {\displaystyle \mathrm {B} (\mu ^{+}\to e^{+}\gamma )<4.2\times 10^{-13}}

<p>at 90% confidence level, <a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> based on data collected in 2009–2013. This improved the MEG limit from the prior MEGA experiment<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> by a factor of about 28.
</p>
<h2 id="apparatus">Apparatus</h2>
<p>MEG uses a continuous muon beam (3 × 107/s) incident on a plastic target.  The decay is reconstructed to look for a back-to-back <a href="/facts/Positron/HgV4zBzA">positron</a> and monochromatic photon (52.8 MeV).  A liquid xenon <a href="/facts/Scintillator/vhxA1Ufo">scintillator</a> with <a href="/facts/Photomultiplier/lVDdAH5d">photomultiplier tubes</a> measure the photon energy, and a <a href="/facts/Wire_chamber/BKstxtE9">drift chamber</a> in a magnetic field detects the positrons.
</p><p>The MEG collaboration presented upgrade plans for MEG-II at the Particles and Nuclei International Conference 2014, with one order of magnitude greater sensitivity, and increased muon production, to begin data taking in 2017.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> More experiments are planned to explore rare muon transitions, such as <a href="/facts/Comet_(experiment)/w1M2F8Pz">Comet (experiment)</a>, <a href="/facts/Mu2e/ICcNQ7B1">Mu2e</a> and <a href="/facts/Mu3e/zIoC8MA6">Mu3e</a>.
</p>

<h2 id="external-links">External links</h2>
<ul><li><a href="https://inspirehep.net/experiments/1679100">MEG-II experiment record</a> on <a href="/facts/INSPIRE-HEP/CDEYl9E1">INSPIRE-HEP</a></li></ul>
<ul><li><a href="http://meg.web.psi.ch/">"MEG home page"</a>.</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>"MEG goes in search of the forbidden". CERN Courier. 27 July 2004. <a href="http://cerncourier.com/cws/article/cern/29118" target="_blank">http://cerncourier.com/cws/article/cern/29118</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Baldini, A. M.; et al. (MEG collaboration) (May 2016). "Search for the Lepton Flavour Violating Decay μ+→e+γ with the Full Dataset of the MEG Experiment". arXiv:1605.05081 [hep-ex]. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Brooks, M. L.; et al. (MEGA Collaboration) (23 August 1999). "New limit for the lepton-family-number nonconserving decay μ+→e+γ". Physical Review Letters. 83 (8): 1521–1524. arXiv:hep-ex/9905013. Bibcode:1999PhRvL..83.1521B. doi:10.1103/PhysRevLett.83.1521. S2CID 119354296. <a href="https://zenodo.org/record/1233921" target="_blank">https://zenodo.org/record/1233921</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>Renga, F (2014). "Latest results of MEG and status of MEG-II". arXiv:1410.4705 [hep-ex]. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
</ol>

Mu to E Gamma open-in-new

Mu to E Gamma