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論文

Measurement of the branching fraction of $$B rightarrow D^{(*)}pi ellnu$$ at Belle using hadronic tagging in fully reconstructed events

Vossen, A.*; 谷田 聖; Belle Collaboration*; 他164名*

Physical Review D, 98(1), p.012005_1 - 012005_9, 2018/07

 被引用回数:2 パーセンタイル:18.61(Astronomy & Astrophysics)

We report a measurement of the branching fraction of the decay $$B rightarrow D^{(*)}pi ellnu$$. The analysis uses 772$$times 10^6$$ $$Bbar{B}$$ pairs produced in $$e^+e^-rightarrow Upsilon(4S)$$ data recorded by the Belle experiment at the KEKB asymmetric-energy $$e^+e^-$$ collider. The tagging $$B$$ meson in the decay is fully reconstructed in a hadronic decay mode. On the signal side, we reconstruct the decay $$B rightarrow D^{(*)}pi ellnu$$ $$(ell=e,mu)$$. The measured branching fractions are $$mathcal{B}(B^+ rightarrow D^-pi^+ ell^+nu)$$ = [4.55 $$pm$$ 0.27 (stat.) $$pm$$ 0.39 (syst.)]$$times 10^{-3}$$, $$mathcal{B}(B^0 rightarrow bar{D}^0pi^- ell^+nu)$$ = [4.05 $$pm$$ 0.36 (stat.) $$pm$$ 0.41 (syst.)]$$times 10^{-3}$$, $$mathcal{B}(B^+ rightarrow D^{*-}pi^+ ell^+nu)$$ = [6.03 $$pm$$ 0.43 (stat.) $$pm$$ 0.38 (syst.)]$$times 10^{-3}$$, and $$mathcal{B}(B^0 rightarrow bar{D}^{*0}pi^- ell^+nu)$$ = [6.46 $$pm$$ 0.53 (stat.) $$pm$$ 0.52 (syst.)]$$times 10^{-3}$$. These are in good agreement with the current world average values.

論文

J-PARC E19 experiment; Pentaquark $$Theta^+$$ search in hadronic reaction at J-PARC

高橋 智則*; 江川 弘行; 早川 修平; 細見 健二; 市川 裕大; 今井 憲一; 佐甲 博之; 佐藤 進; 杉村 仁志; 谷田 聖; et al.

JPS Conference Proceedings (Internet), 8, p.022011_1 - 022011_6, 2015/09

A search for the $$Theta^+$$ pentaquark in the $$pi^-p to K^-X$$ reaction was performed at the J-PARC Hadron Facility. Two data samples were collected in 2010 and 2012 at $$pi^-$$ beam momenta of 1.92 and 2.0 GeV/$$c$$, respectively. No peak structure was observed in the missing mass spectra obtained from either data set. The upper limit for the production cross section averaged over the scattering-angle range of $$2^{circ}$$ to $$15^{circ}$$ in the laboratory frame was found to be 0.28 $$mu$$b/sr. The decay width of the $$Theta^+$$ can be directly connected to the production cross section through a theoretical calculation using an effective Lagrangian. The estimated upper limits of the width were 0.41 and 2.8 MeV for the spin-parities of $$1/2^+$$ and $$1/2^-$$, respectively.

論文

Search for the $$Theta^{+}$$ pentaquark via the $$pi^-prightarrow K^-X$$ reaction at 1.92 GeV/$$c$$

白鳥 昂太郎; 今井 憲一; 佐甲 博之; 佐藤 進; 他64名*

Physical Review Letters, 109(13), p.132002_1 - 132002_5, 2012/09

J-PARCにおいて$$Theta^+$$ペンタクォークの探索実験を1.4MeV/$$c^2$$の高分解能の$$pi^-prightarrow K^-X$$を用いて行った。1.92GeV/$$c$$$$pi$$中間子ビームを液体水素標的に照射し生成を試みた。しかしながら、ミッシングマススペクトルに明瞭なピーク構造を観測することはできなかった。質量領域1.51-1.55GeV/$$c^2$$にて、微分生成断面積の上限値を$$K$$の散乱角度2$$^{circ}$$から15$$^{circ}$$の範囲で求め0.26$$mu$$b/srを得た。この生成断面積の上限値から$$Theta^+$$の幅の上限値をeffective Lagrangianによる理論計算を用いて求め、スピンパリティに応じ、0.72MeV/$$c^2(1/2^+)$$と3.1MeV/$$c^2(1/2^-)$$を得た。

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