Observation of B0 to Lambda Lambdabar K0 and B0 to Lambda Lambdabar K*0 at Belle - High Energy Physics - ExperimentReportar como inadecuado




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Abstract: We study the charmless decays B to Lambda Lambdabar h, where h stands forpi^+, K^+,K^0,K^{*+}, or K^{*0}, using a 605 fb^{-1} data sample collected atthe Upsilon4Sresonance with the Belle detector at the KEKB asymmetric energye^+ e^- collider. We observe B0 to Lambda Lambdabar K0 and B0 to LambdaLambdabar K*0 with branching fractions of 4.76^{+0.84} {-0.68} stat. \pm0.61 syst. \times 10^{-6} and 2.46^{+0.87} {-0.72} \pm 0.34 \times10^{-6}, respectively. The significances of these signals in the threshold-massenhanced mass region are 12.4 sigma and 9.3 sigma, respectively. We also updatethe branching fraction BFB+ to Lambda Lambdabar K+ = 3.38^{+0.41} {-0.36}\pm 0.41\times 10^{-6} with better accuracy,and report the followingmeasurement or 90% confidence level upper limit in the threshold-mass-enhancedregion: BFB+ to Lambda Lambdabar K*+ = 2.19^{+1.13} {-0.89} \pm 0.33 \times10^{-6} with 3.7 sigma significance; BFB+ to Lambda Lambdabar pi+ < 0.94\times 10^{-6}. A related search for B0 to Lambda Lambdabar D0bar yields abranching fraction BFB0 to Lambda Lambdabar D0bar = 1.05 {-0.44}^{+0.57} \pm0.13\times 10^{-5}. This may be compared with the large, ~10^{-4}, branchingfraction observed for B0 to p pbar D0bar. The m {Lambda Lambdabar} enhancementsnear threshold and related angular distributions for the observed modes arealso reported.PACS:13.25.Hw, 14.40.Nd



Autor: Y.-W.Chang, M.-Z.Wang, et al

Fuente: https://arxiv.org/



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