An amplitude analysis of the $B^{0}\to K^{*0}\mu^+\mu^-$ decay is presented using a dataset corresponding to an integrated luminosity of $4.7$ fb$^{-1}$ of $pp$ collision data collected with the LHCb experiment. For the first time, the coefficients associated to short-distance physics effects, sensitive to processes beyond the Standard Model, are extracted directly from the data through a $q^2$-unbinned amplitude analysis, where $q^2$ is the $\mu^+\mu^-$ invariant mass squared. Long-distance contributions, which originate from non-factorisable QCD processes, are systematically investigated and the most accurate assessment to date of their impact on the physical observables is obtained. The pattern of measured corrections to the short-distance couplings is found to be consistent with previous analyses of $b$- to $s$-quark transitions, with the largest discrepancy from the Standard Model predictions found to be at the level of 1.8 standard deviations. The global significance of the observed differences in the decay is 1.4 standard deviations.
Illustration of the $q^2$ spectrum in $B^0\rightarrow K^{*0}\mu ^+\mu ^- $ decays. The dashed line corresponds to the pure rare semileptonic decay, while the solid line includes the impact of different charmonium resonances. The gray bands correspond to the regions dominated by $B^0\rightarrow { J \mskip -3mu/\mskip -2mu\psi } K^{*0}$ and $B^0\rightarrow \psi {(2S)} K^{*0}$ tree-level decays. Magnitudes and phases of $c\bar{c}$ resonant components have been arbitrarily chosen for illustrative purposes. The dominant Wilson coefficients in each region of the spectrum are also highlighted for reference. |
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Two-dimensional profile-likelihood contours of the (left) $\mathcal{C}_9^{\mathrm{BSM}}$--$\mathcal{C}_{10}^{\mathrm{BSM}}$ and (right) $\mathcal{C}_9^{\prime \mathrm{BSM}}$--$\mathcal{C}_{10}^{\prime \mathrm{BSM}}$ pairs of Wilson coefficients at $68\%$ confidence level with (blue) and without (red) SM constraints at $q^{2}<0$. The fit is also repeated considering local FFs to be fixed to their SM predictions (grey) [16,25,31]. |
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Determination of the (top) $P^{\prime}_{5}$ and (bottom) $S_7$ angular observables obtained from the amplitude fit. Results are shown for fits with (blue) and without (red) constraints from $q^{2} < 0$, at 68% confidence level. The LHCb binned angular analysis [10] (black dots) and SM predictions from DHMV [33,68] (green) and GRvDV [16,25,31] (yellow) are overlaid for reference. The center panel shows the non-local contributions to $P^{\prime}_{5}$ determined from the amplitude fit. Here the difference between the LHCb binned angular analysis [10] and SM central value from DHMV is overlaid for reference (black dots), together with the uncertainty on the DHMV SM prediction (green) and difference between the SM predictions from GRvDV and DHMV (yellow). Theoretical predictions are shown only for $q^2 < 8\text{ Ge V} ^2 /c^4 $. |
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Non-local contributions to the angular observables (P-basis) obtained from data fits with (blue) and without (red) constraints from $q^{2} < 0$. The shaded regions are shown at 68% confidence level. When available, the difference between the LHCb binned angular analysis [10] and SM central-value from Refs. [33,68] is overlaid for reference (black dots), together with the uncertainty on the SM prediction (green). |
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Non-local contributions to the angular observables (S-basis) obtained from data fits with (blue) and without (red) constraints from $q^{2} < 0$. The shaded regions are shown at 68% confidence level. When available, the difference between the LHCb binned angular analysis [10] and SM central-value from Refs. [23,70] is overlaid for reference (black dots), together with the uncertainty on the SM prediction (green) and difference between the SM predictions from Refs. [16,25,31] with respect to Refs. [23,70] (yellow). |
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Created on 18 May 2024.