Abstract
In this paper, we study the light scalar and pseudoscalar invisible particles in the flavor changing neutral current processes of the Bc meson. Effective operators are introduced to describe the couplings between quarks and light invisible particles. The Wilson coefficients are extracted from the experimental results of the B and D mesons, which are used to predict the upper limits of the branching fractions of the similar decay processes for the Bc meson. The hadronic transition matrix element is calculated with the instantaneously approximated Bethe-Salpeter method. The upper limits of the branching fractions when mχ taking different values are presented. It is found that at some region of mχ, the channel Bc → Ds(*)χχ has the largest upper limit which is of the order of 10−6, and for Bc → Ds*χχ†, the largest value of the upper limits can achieve the order of 10−5. Other decay modes, such as Bc → D(*)χχ(†) and Bc → B(*)χχ(†), are also considered.
Highlights
JHEP03(2019)028 the SM fermions through different ways
The Wilson coefficients are extracted from the experimental results of the B and D mesons, which are used to predict the upper limits of the branching fractions of the similar decay processes for the Bc meson
We will not focus on any specific model, but consider the flavor-changing neutral current (FCNC) processes of Bc meson induced by such effective operators
Summary
By comparing the theoretical predictions and the experimental upper limits (the third column of table 1) of the branching ratios for these decays, we can set the upper bounds for the effective coupling constants gs and gs with specific mass of the invisible particle. Comparing the theoretical predictions and the experimental upper bound of these channels, we give the possible relations of the modulus square of the effective coupling constants, which are presented in figure 5. In this figure, the area below the colored line is allowed experimentally with a specific mass of χ. In figure 6, we show that the experimentally allowed region is that under the colored plane which corresponding a specific mass of χ
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