Abstract
A search for the D0→π+π−μ+μ− decay, where the muon pair does not originate from a resonance, is performed using proton–proton collision data corresponding to an integrated luminosity of 1.0fb−1 recorded by the LHCb experiment at a centre-of-mass energy of 7 TeV. No signal is observed and an upper limit on the relative branching fraction with respect to the resonant decay mode D0→π+π−ϕ(→μ+μ−), under the assumption of a phase-space model, is found to beB(D0→π+π−μ+μ−)/B(D0→π+π−ϕ(→μ+μ−))<0.96 at 90% confidence level. The upper limit on the absolute branching fraction is evaluated to be B(D0→π+π−μ+μ−)<5.5×10−7 at 90% confidence level. This is the most stringent to date.
Highlights
The upper limit on the absolute branching fraction is evaluated to be Flavour-changing neutral current (FCNC) processes are rare within the Standard Model (SM) as they cannot occur at tree level and are suppressed by the Glashow–Iliopoulos–Maiani (GIM)
This suppression allows for subleading processes with potential for physics beyond the SM, such as FCNC decays of D mesons, and the coupling of up-type quarks in electroweak processes illustrated in Fig. 1, to be probed more precisely
A search for the D0 → π +π −μ+μ− decay is conducted usionfg1.p0pfbc−o1llisaiton√sd=ata7, corresponding to an TeV recorded by the integrated luminosity LHCb experiment
Summary
Flavour-changing neutral current (FCNC) processes are rare within the Standard Model (SM) as they cannot occur at tree level and are suppressed by the Glashow–Iliopoulos–Maiani (GIM). In contrast to the B meson system, where the high mass of the top quark in the loop weakens the suppression, the GIM cancellation is almost exact [1] in D meson decays, leading to expected branching fractions for c → uμ+μ− processes in the range (1 − 3) × 10−9 [2,3,4]. This suppression allows for subleading processes with potential for physics beyond the SM, such as FCNC decays of D mesons, and the coupling of up-type quarks in electroweak processes illustrated, to be probed more precisely. D0 → π +π −φ(→ μ+μ−) decays, isolated in an appropriate dimuon range centred around the φ pole
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