ϒandϒ′leptonic widths,aμb, andmbfrom full lattice QCD
| Autor: | K. Hornbostel, R. J. Dowdall, Christine Davies, B. Colquhoun, G. P. Lepage |
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| Rok vydání: | 2015 |
| Předmět: | |
| Zdroj: | Physical Review D. 91 |
| ISSN: | 1550-2368 1550-7998 |
| DOI: | 10.1103/physrevd.91.074514 |
| Popis: | We determine the decay rate to leptons of the ground-state $\mathrm{\ensuremath{\Upsilon}}$ meson and its first radial excitation in lattice QCD for the first time. We use radiatively improved nonrelativistic QCD for the $b$ quarks and include $u$, $d$, $s$ and $c$ quarks in the sea with $u/d$ masses down to their physical values. We find $\mathrm{\ensuremath{\Gamma}}(\mathrm{\ensuremath{\Upsilon}}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}})=1.19(11)\text{ }\text{ }\mathrm{keV}$ and $\mathrm{\ensuremath{\Gamma}}({\mathrm{\ensuremath{\Upsilon}}}^{\ensuremath{'}}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}})=0.69(9)\text{ }\text{ }\mathrm{keV}$, both in good agreement with experimental results. The decay constants we obtain are included in a summary plot of meson decay constants from lattice QCD given in the Conclusions. We also test time moments of the vector current-current correlator against values determined from the $b$-quark contribution to $\ensuremath{\sigma}({e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\text{hadrons})$ and calculate the $b$-quark piece of the hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon, ${a}_{\ensuremath{\mu}}^{b}=0.271(37)\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}10}$. Finally we determine the $b$-quark mass, obtaining in the $\overline{\mathrm{MS}}$ scheme, ${\overline{m}}_{b}({\overline{m}}_{b},{n}_{f}=5)=4.196(23)\text{ }\text{ }\mathrm{GeV}$, the most accurate result from lattice QCD to date. |
| Databáze: | OpenAIRE |
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