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• 作者：R. Aaij ; B. Adeva ; M. Adinolfi ; Z. Ajaltouni ; S. Akar…
• 刊名：The European Physical Journal C
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：77
• 期：2
• 全文大小：1081KB
• 刊物类别：Physics and Astronomy
• 刊物主题：Elementary Particles, Quantum Field Theory; Nuclear Physics, Heavy Ions, Hadrons; Quantum Field Theories, String Theory; Measurement Science and Instrumentation; Astronomy, Astrophysics and Cosmology;
• 出版者：Springer Berlin Heidelberg
• ISSN：1434-6052
• 卷排序：77

文摘

The decays \({{\mathrm {B}} ^+} \rightarrow {{\mathrm {J}/\uppsi }} 3{{\uppi } ^+} 2{{\uppi } ^-} \) and \({{\mathrm {B}} ^+} \rightarrow {\uppsi {(2\mathrm {S})}} {{\uppi } ^+} {{\uppi } ^+} {{\uppi } ^-} \) are observed for the first time using a data sample corresponding to an integrated luminosity of 3.0 fb\(^{-1}\), collected by the LHCb experiment in proton–proton collisions at the centre-of-mass energies of 7 and 8\(\mathrm {\,TeV}\). The branching fractions relative to that of \({{\mathrm {B}} ^+} \rightarrow {\uppsi {(2\mathrm {S})}} {{\mathrm {K}} ^+} \) are measured to be $$\begin{aligned} \dfrac{{\mathcal {B}} ( {{\mathrm {B}} ^+} \rightarrow {{\mathrm {J}/\uppsi }} 3{{\uppi } ^+} 2{{\uppi } ^-} )}{{\mathcal {B}} ( {{\mathrm {B}} ^+} \rightarrow {\uppsi {(2\mathrm {S})}} {{\mathrm {K}} ^+} )}= & {} ( 1.88\!\pm \! 0.17\!\pm \! 0.09)\!\times \! 10^{-2}, \\ \dfrac{{\mathcal {B}} ( {{\mathrm {B}} ^+} \rightarrow {\uppsi {(2\mathrm {S})}} {{\uppi } ^+} {{\uppi } ^+} {{\uppi } ^-} )}{{\mathcal {B}} ( {{\mathrm {B}} ^+} \rightarrow {\uppsi {(2\mathrm {S})}} {{\mathrm {K}} ^+} )}= & {} ( 3.04\!\pm \!0.50\!\pm \!0.26)\!\times \! 10^{-2}, \end{aligned}$$where the first uncertainties are statistical and the second are systematic.1 IntroductionThe \({\mathrm {B}} ^+\)  meson is a bound state of a heavy \({\overline{{\mathrm {b}}}} \) quark and a \({\mathrm {u}} \) quark, with well known properties and a large number of decay modes [1], but little is known about decays of \({{\mathrm {B}} ^+} \) mesons to a \({\mathrm {J}/\uppsi }\) meson plus a large number of light hadrons. The \({{\mathrm {B}} ^+} \rightarrow {{\mathrm {J}/\uppsi }} 3{{\uppi } ^+} 2{{\uppi } ^-} \) decay channel is of particular interest, since it is one of the highest multiplicity final states currently experimentally accessible. Evidence for the corresponding decay of the \({\mathrm {B}} _{\mathrm {c}} ^+\) meson has recently been reported by the LHCb collaboration [2], with the measured branching fraction and qualitative behaviour of the multipion system consistent with expectations from QCD factorisation [3, 4]. In this scheme, the \({{\mathrm {B}} _{\mathrm {c}} ^+} \rightarrow {{\mathrm {J}/\uppsi }} 3{{\uppi } ^+} 2{{\uppi } ^-} \) decay is characterized by the form factors of the \({{\mathrm {B}} _{\mathrm {c}} ^+} \rightarrow {{\mathrm {J}/\uppsi }} \mathrm {W} ^+\) transition and the spectral functions for the conversion of the \(\mathrm {W} ^+\) boson into light hadrons [5–8]. Different decay topologies contribute to decays of \({\mathrm {B}} ^+\)  mesons into charmonia and light hadrons, affecting the dynamics of the multipion system and enabling the role of factorisation in \({\mathrm {B}} ^+\)  meson decays to be probed.