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CMS-PAS-BPH-20-003
Combination of the ATLAS, CMS and LHCb results on the B0(s)μ+μ decays
Abstract: A combination of results on the rare B0sμ+μ and B0μ+μ decays from the ATLAS, CMS, and LHCb experiments using data collected at the Large Hadron Collider between 2011 and 2016, is presented. The B0sμ+μ branching fraction is obtained to be (2.69 +0.370.35) × 109 and the effective lifetime of the B0sμ+μ decay is measured to be τB0sμ+μ= 1.91+0.370.35 ps. An upper limit on the B0μ+μ branching fraction is evaluated to be B(B0μ+μ)< 1.6 (1.9) × 1010 at 90% (95%) confidence level. An upper limit on the ratio of the B0μ+μ and B0sμ+μ branching fractions is obtained to be 0.052 (0.060) at 90% (95%) confidence level.
Figures Summary References CMS Publications
Figures

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Figure 1:
In the left-hand plot, the two-dimensional likelihood contours of the results for the B0sμ+μ and B0μ+μ decays for the three experiments are shown together with their combination. The dataset used was collected from 2011 to 2016. The red dashed line represents the ATLAS experiment, the green dot-dashed line the CMS experiment, the blue long-dashed line the LHCb experiment and the continuous line their combination. For each experiment and for the combination, likelihood contours correspond to the values of 2ΔlnL= 2.3, 6.2, and 11.8, respectively. In the right-hand plot, the combination of the three experiments is shown with contours of different shades. Likelihood contours correspond to the values of 2ΔlnL= 2.3, 6.2, 11.8, 19.3, and 30.2, represented in order by darkest to less dark colour. In both plots, the red point shows the SM predictions with their uncertainties. The published results from the three experiments are detailed in Ref. [1,2,3].

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Figure 1-a:
The two-dimensional likelihood contours of the results for the B0sμ+μ and B0μ+μ decays for the three experiments are shown together with their combination. The dataset used was collected from 2011 to 2016. The red dashed line represents the ATLAS experiment, the green dot-dashed line the CMS experiment, the blue long-dashed line the LHCb experiment and the continuous line their combination. For each experiment and for the combination, likelihood contours correspond to the values of 2ΔlnL= 2.3, 6.2, and 11.8, respectively. The red point shows the SM predictions with their uncertainties. The published results from the three experiments are detailed in Ref. [1,2,3].

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Figure 1-b:
The combination of the three experiments is shown with contours of different shades. Likelihood contours correspond to the values of 2ΔlnL= 2.3, 6.2, 11.8, 19.3, and 30.2, represented in order by darkest to less dark colour. The red point shows the SM predictions with their uncertainties. The published results from the three experiments are detailed in Ref. [1,2,3].

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Figure 2:
Value of 2ΔlnL for B(B0sμ+μ) (left) and B(B0μ+μ) (right), shown in both as solid black line. In the left-hand plot, the dark (light) green dashed lines represent the 1σ (2σ) interval. In the right-hand plot, the dark (light) blue dashed lines represent the 90% (95%) CL. In both plots, the red solid band shows the SM prediction with its uncertainty. The published results from the three experiments are detailed in Ref. [1,2,3].

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Figure 2-a:
Value of 2ΔlnL for B(B0sμ+μ), shown as solid black line. The dark (light) blue dashed lines represent the 90% (95%) CL. The red solid band shows the SM prediction with its uncertainty. The published results from the three experiments are detailed in Ref. [1,2,3].

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Figure 2-b:
Value of 2ΔlnL for B(B0μ+μ), shown as solid black line. The dark (light) blue dashed lines represent the 90% (95%) CL. The red solid band shows the SM prediction with its uncertainty. The published results from the three experiments are detailed in Ref. [1,2,3].

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Figure 3:
Value of 2ΔlnL for the ratio of the B0μ+μ and B0sμ+μ branching fractions, R, shown as solid black line. The light (dark) blue dashed line represents the 90% (95%) CL and the red solid band shows the SM prediction with its uncertainty. The published results from the three experiments are detailed in Ref. [1,2,3].

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Figure 4:
Value of 2ΔlnL for the combination of CMS and LHCb measurements [2,3] of the B0sμ+μ effective lifetime, shown as solid black line. The dark and light green dashed lines represent the intervals corresponding to 2ΔlnL=1 and 4, respectively, and the red solid band shows the SM prediction with its uncertainty.
Summary
In summary, the results of the ATLAS, CMS, and LHCb experiments on the B0s,dμ+μ decays obtained from the data collected between 2011 and 2016 have been combined.
References
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