Decays $D^+_{(s)}\to \pi(K)^{+}\ell^+\ell^-$ and D⁰→ℓ⁺ℓ^- in the MSSM with and without R-parity

The new physics reach of null tests with $$D \rightarrow \pi \ell \ell $$ and $$D_s \rightarrow K \ell \ell $$ decays

“…Another possibility to probe SUSY in c → u FCNCs is with R-parity violating terms λ L Q D, which induce (axial)-vector couplings with C 9 = −C 10 through tree level exchange of a scalar partner of a singlet down quark, see [1] for details; also [35]. However, this unavoidably involves doublet up-type quarks, hence is subject to constraints from rare kaon decays, specifically K → πνν.…”

“…For the models presented F R / F L ranges within ∼ [0. 9,35]. Also given are the values of the mixing angle θ u for each model.…”

Charm decays

“…The present experimental upper limit B exp < 6.2 × 10 −9 by LHCb [34] sets the strongest constraints on the difference of (pseudo)scalar Wilson coefficients. While the SM branching ratio is commonly estimated orders of magnitude below B exp [35,36,37], a BSM-induced branching ratio close to the experimental limit is allowed within, e.g., two Higgs doublet and leptoquark models [26,33,35,37,38,39,40]. The decay into electrons is, on the other hand, helicity suppressed and diluted by misidentification from O(αm 2 D /m 2 e ) enhanced D 0 → e + e − γ decays with soft photons [28].…”

“…D → P and D → PP , SM CP-asymmetries are small, A SM CP ∼ Im λ b λ s ∼ 10 −3 . Further SM null test are given in terms of angular observables, [26,33,35,39,40,48,49,50,51,52,53,54,55,56,57,58,59].…”

Null test searches for BSM physics with rare charm decays

“…The experimental and theoretical status of rare charm decays is presented in Ref. [5] and increasing and ongoing research interest [1,2,[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] manifests the importance of progress in the field.…”