Measurement of the branching fraction of B^+ -> tau^+ nu_tau decays with the semileptonic tagging method
Belle Collaboration, B. Kronenbitter, M. Heck, P. Goldenzweig, T. Kuhr, A. Abdesselam, I. Adachi, H. Aihara, S. Al Said, K. Arinstein, D. M. Asner, T. Aushev, R… 展开作者
Belle Collaboration, B. Kronenbitter, M. Heck, P. Goldenzweig, T. Kuhr, A. Abdesselam, I. Adachi, H. Aihara, S. Al Said, K. Arinstein, D. M. Asner, T. Aushev, R. Ayad, T. Aziz, A. M. Bakich, V. Bansal, E. Barberio, V. Bhardwaj, A. Bondar, G. Bonvicini, A. Bozek, M. Bračko, T. E. Browder, D. Červenkov, V. Chekelian, A. Chen, B. G. Cheon, K. Chilikin, R. Chistov, K. Cho, V. Chobanova, Y. Choi, D. Cinabro, J. Dalseno, M. Danilov, J. Dingfelder, Z. Doležal, Z. Drásal, A. Drutskoy, D. Dutta, S. Eidelman, D. Epifanov, H. Farhat, J. E. Fast, T. Ferber, O. Frost, B. G. Fulsom, V. Gaur, N. Gabyshev, A. Garmash, D. Getzkow, R. Gillard, R. Glattauer, B. Golob, J. Grygier, K. Hayasaka, H. Hayashii, X. H. He, M. Heider, A. Heller, T. Horiguchi, M. Huschle, T. Iijima, K. Inami, A. Ishikawa, R. Itoh, Y. Iwasaki, I. Jaegle, K. K. Joo, T. Julius, K. H. Kang, E. Kato, D. Y. Kim, H. J. Kim, J. B. Kim, J. H. Kim, K. T. Kim, M. J. Kim, S. H. Kim, Y. J. Kim, K. Kinoshita, B. R. Ko, P. Kodyš, P. Križan, P. Krokovny, A. Kuzmin, Y. -J. Kwon, J. S. Lange, D. H. Lee, I. S. Lee, P. Lewis, L. Li Gioi, J. Libby, D. Liventsev, P. Lukin, D. Matvienko, H. Miyata, R. Mizuk, G. B. Mohanty, S. Mohanty, A. Moll, H. K. Moon, R. Mussa, E. Nakano, M. Nakao, T. Nanut, Z. Natkaniec, M. Nayak, N. K. Nisar, S. Nishida, S. Okuno, S. L. Olsen, W. Ostrowicz, C. Oswald, P. Pakhlov, G. Pakhlova, H. Park, T. K. Pedlar, L. Pesántez, R. Pestotnik, M. Petrič, L. E. Piilonen, C. Pulvermacher, E. Ribežl, M. Ritter, A. Rostomyan, S. Ryu, Y. Sakai, L. Santelj, T. Sanuki, Y. Sato, V. Savinov, O. Schneider, G. Schnell, M. Schram, C. Schwanda, K. Senyo, O. Seon, M. E. Sevior, V. Shebalin, T. -A. Shibata, J. -G. Shiu, B. Shwartz, A. Sibidanov, F. Simon, Y. -S. Sohn, A. Sokolov, E. Solovieva, S. Stanič, M. Starič, M. Steder, T. Sumiyoshi, U. Tamponi, Y. Teramoto, K. Trabelsi, M. Uchida, S. Uehara, T. Uglov, Y. Unno, S. Uno, P. Urquijo, Y. Usov, C. Van Hulse, P. Vanhoefer, G. Varner, A. Vinokurova, A. Vossen, M. N. Wagner, C. H. Wang, M. -Z. Wang, P. Wang, M. Watanabe, Y. Watanabe, K. M. Williams, E. Won, H. Yamamoto, S. Yashchenko, Y. Yook, Z. P. Zhang, V. Zhilich, V. Zhulanov, M. Ziegler, A. Zupanc
我们使用772 x 10^6个BBbar对的数据样本测量了B^+ -> tau^+ nu_tau衰变的分支分数,这些数据样本是在KEKB非对称能量e^+e^-对撞机上用Belle探测器在Y(4S)共振处收集的。我们在半轻子衰变中重建了伴随的B介子,并在衰变通道B^+ -> tau^+ nu_tau中探测到反冲的B介子候选者。我们得到了BR(B^+ -> tau^+ nu_tau)= [1.25 +- 0.28(stat.)+- 0.27(系统)] x 10^-4。这一结果与以前的测量结果和基于标准模型的计算结果吻合得很好。
英文摘要:
We report a measurement of the branching fraction of B^+ -> tau^+ nu_tau decays using a data sample of 772 x 10^6 BBbar pairs, collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^+e^- collider. We reconstruct the accompanying B meson in a semileptonic decay and detect the recoiling B candidate in the decay channel B^+ -> tau^+ nu_tau. We obtain a branching fraction of BR(B^+ -> tau^+ nu_tau) = [1.25 +- 0.28 (stat.) +- 0.27 (syst.)] x 10^-4. This result is in good agreement with previous measurements and the expectation from the calculation based on the Standard Model.
We report a measurement of the ratios of branching fractions $\mathcal{R}(D^{(*)}) = {\cal B}(\bar{B} \to D^{(*)} τ^- \barν_τ)/{\cal B}(\bar{B} \to D^{(*)} \ell^- \barν_{\ell})$ where $\ell$ denotes an electron or a muon. The results are based on a data sample containing $772 \times 10^6$ $B\bar{B}$ events recorded at the $Υ(4S)$ resonance with the Belle detector at the KEKB $e^+ e^-$ collider. The tag-side B meson is reconstructed in a semileptonic decay mode, and the signal-side $τ$ is reconstructed in a purely leptonic decay. The results are $\mathcal{R}(D) = 0.307 \pm 0.037 \pm 0.016$ and …
We report the first direct measurement of the inclusive branching fraction ${\mathcal B}(B_s \rightarrow D_s X)$ via $B_s$ tagging in $e^+e^-\toΥ$(5S) events. Tagging is accomplished through a partial reconstruction of semileptonic decays $B_s \rightarrow D_s X \ell ν$, where $X$ denotes unreconstructed additional hadrons or photons and $\ell$ is an electron or muon. With 121.4 fb$^{-1}$ of data collected at the $Υ$(5S) resonance by the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider, we obtain ${\mathcal B}(B_s \rightarrow D_s X)$ = $(60.2 \pm 5.8 \pm 2.3)$\%, where the first …
New light on WW scattering at the LHC with W jet tagging
最近在大型强子对撞机(LHC)上发现了125 GeV的类Higgs粒子,研究其在高能W_LW_L散射中的作用至关重要,这可能揭示其与标准模型Higgs的可能偏离。我们进行了更新的研究WW散射的半轻子通道在LHC,最近开发的W喷注标记方法改进。由此产生的强相互作用轻希格斯(SILH)模型的统计意义是大约20%以上的传统的“镀金”双轻子通道的基础上,而200%以上的信号事件被保留。如果信号强度是纯无希格斯粒子模型的100%(10%),这允许在14 TeV LHC上使用大约40(3000)fb^{-1}数据发现SILH模型。同时,对反常Higgs-W玻色子耦合的出色灵敏度使得半轻子WW散射成为Higgs共振精确测量的重要补充。
The Belle II experiment at the SuperKEKB energy-asymmetric $e^+ e^-$ collider is a substantial upgrade of the B factory facility, Belle, at the Japanese KEK laboratory. The main operation of SuperKEKB has started in March 2019, and collisions ran until July 2019, achieving a peak luminosity of $5.5\times 10^{33}$ cm$^{-2}$s$^{-1}$. The results presented here were obtained from a subset of collected data of 0.41 fb$^{-1}$. In the poster presented at the conference the first results from studying semileptonic $\textit{B}$-meson decays were shown. The performance of the Full Event Interpretation …
Measurement of the $\ttbar$ Production Cross Section in 2 fb$^{-1}$ of $\ppbar$ Collisions at $\sqrt{s}=1.96$ TeV Using Lepton Plus Jets Events with Soft Muon b-Tagging
This proceeding summarizes the recent measurements of semileptonic $b\to u$ decays from the Belle experiment. These analyses use the full data set collected at the $Υ(4S)$ resonance at KEKB accelerator complex with a center-of-mass energy of $\sqrt{s} = 10.58$ GeV, which contains an integrated luminosity of 711 fb$^{-1}$ and corresponds to 772 million $Υ(4S) \to B\bar{B}$ events. In the sector of inclusive decay, the partial branching fraction of $B \to X_{u} \ell ν$ decays and the CKM matrix element $|V_{ub}|$ are measured with hadronic tagging. The first measurement of differential branching…
The Belle II experiment at the SuperKEKB energy-asymmetric $e^+e^-$ collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The design luminosity of the machine is $8\times10^{35}\, \mathrm{cm}^{-2}\mathrm{s}^{-1}$ and the Belle II experiment aims to record $50\, \mathrm{ab}^{-1}$ of data, a factor of 50 more than its predecessor. From February to July 2018, SuperKEKB has completed a commissioning run, achieved a peak luminosity of $5.5 \times 10^{33}\, \mathrm{cm}^{-2}\mathrm{s}^{-1}$, and Belle II recorded a data sample of about $0.5\, \mathrm{fb}^{-1}$. I…
The experimental results on the ratios of branching fractions $\mathcal{R}(D) = {\cal B}(\bar{B} \to D τ^- \barν_τ)/{\cal B}(\bar{B} \to D \ell^- \barν_{\ell})$ and $\mathcal{R}(D^*) = {\cal B}(\bar{B} \to D^* τ^- \barν_τ)/{\cal B}(\bar{B} \to D^* \ell^- \barν_{\ell})$, where $\ell$ denotes an electron or a muon, show a long-standing discrepancy with the Standard Model predictions, and might hint to a violation of lepton flavor universality. We report a new simultaneous measurement of $\mathcal{R}(D)$ and $\mathcal{R}(D^*)$, based on a data sample containing $772 \times 10^6$ $B\bar{B}$ events…
We perform a global analysis of exclusive hadronic tau decays into one and two mesons using the low-energy limit of the Standard Model Effective Field Theory up to dimension six, assuming left-handed neutrinos. A controlled theoretical input on the Standard Model hadronic form factors, based on chiral symmetry, dispersion relations, data and asymptotic QCD properties, has allowed us to set bounds on the New Physics effective couplings using the present experimental data. Our results highlight the importance of semileptonic $τ$ decays in complementing the traditional low-energy probes, such nuc…
Measurement of the branching ratio of $\bar{B}^0 \rightarrow D^{*+} τ^- \barν_τ$ relative to $\bar{B}^0 \rightarrow D^{*+} \ell^- \barν_{\ell}$ decays with a semileptonic tagging method
Based on the mechanism of neutral meson mixing, we predict the branching fraction of the semileptonic decay of $D_s^+\to π^0 \ell^+ ν_\ell$ ($\ell=e$, $μ$) using recently measured branching fraction of $D_s^+\to ηe^+ν_e$ by BESIII experiment . We also give a formula that can describe the neutral meson mixing of $π^0$, $η$, $η'$ and a pseudoscalar gluonium $G$ in a unified way. The predicted branching fraction of $D_s^+\toπ^0 e^+ν_e$ decay is $\mathcal{B}(D_s^+\toπ^0 e^+ν_e)=(2.65\pm 0.38)\times 10^{-5}$. It is important to search for the decay $D_s^+\to π^0 \ell^+ ν_\ell$ in experiment, in ord…
Measurement of the t anti-t Production Cross Section in p anti-p Collisions at s**(1/2) = 1.96 TeV using Missing E(t) + jets Events with Secondary Vertex b-Tagging