Decays of Bs and B0 mesons into J/\psi \pi +\pi -\pi +\pi - final states, produced in pp collisions at the LHC, are investigated using data corresponding to an integrated luminosity of 3/fb collected with the LHCb detector. B^0_(s) -> J\psi f_1(1285) decays are seen for the first time, and the branching fractions are measured. Using these rates, the f_1(1285) mixing angle between strange and non-strange components of its wave function in the q-qbar structure model is determined to be \pm (24.0^{+3.1+0.6}_{-2.6-0.8}) degrees. Implications on the possible tetraquark nature of the f_1(1285) are discussed.
Invariant mass distribution for $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi^+\pi^-\pi^+\pi^-$ combinations. The data are fit with Crystal Ball functions for $\overline{ B }{} ^0$ [(red) dashed curve] and $\overline{ B }{} ^0_ s $ [(purple) dot-dashed curve] signals, an exponential function for combinatoric background (black) dotted, and a Gaussian shape for lower mass background (blue) long-dashed. The total is shown with a (blue) solid curve. |
fitdata.pdf [43 KiB] HiDef png [456 KiB] Thumbnail [257 KiB] *.C file |
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Background subtracted invariant mass distributions of the four pions in (a) $\overline{ B }{} ^0_ s $ and (b) $\overline{ B }{} ^0$ decays are shown in the histogram overlaid with the (black) filled points with the error bars indicating the uncertainties. The open (red) circles show the helicity $\pm$1 components of the signals. |
m4pi_h[..].pdf [38 KiB] HiDef png [287 KiB] Thumbnail [191 KiB] *.C file |
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Fits to the four-pion invariant mass in (a) $\overline{ B }{} ^0_ s $ and (b) $\overline{ B }{} ^0$ decays. The data are shown as points, the signals components as (black) dashed curves, the combinatorial background by (black) dotted curves, and the higher mass resonance tail by (red) dot-dashed curves. |
fitB-f[..].pdf [39 KiB] HiDef png [337 KiB] Thumbnail [182 KiB] *.C file |
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Animated gif made out of all figures. |
PAPER-2013-055.gif Thumbnail |
Fit results for $\overline{ B }{} ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} f_1(1285)$ and $\overline{ B }{} ^0 \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} f_1(1285)$ decays. |
Table_1.pdf [43 KiB] HiDef png [30 KiB] Thumbnail [15 KiB] tex code |
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Systematic uncertainties of the branching fractions ${\cal{B}}(\overline{ B }{} \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} f_1(1285) , f_1(1285)\rightarrow \pi^+\pi^-\pi^+\pi^-)$ and the $\overline{ B }{} ^0 /\overline{ B }{} ^0_ s $ rate ratio. The "+" and "--" signs indicate the positive and negative uncertainties, respectively. All numbers are in (%). |
Table_2.pdf [40 KiB] HiDef png [74 KiB] Thumbnail [35 KiB] tex code |
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Branching fractions used for normalization. |
Table_3.pdf [75 KiB] HiDef png [50 KiB] Thumbnail [24 KiB] tex code |
Created on 27 April 2024.