Measurement of the fraction of Υ (1 S) originating from χb(1 P) decays in pp collisions at $ \sqrt{s}=7\,TeV $

The production of chi(b)(1P) mesons in pp collisions at a centre-of-mass energy of 7 TeV is studied using 32 pb(-1) of data collected with the LHCb detector. The chi(b)(1P) mesons are reconstructed in the decay mode chi(b)(1P) -> Gamma(1S)gamma -> mu(+)mu(-)gamma. The fraction of Gamma(1S) originating from chi(b)(1P) decays in the Gamma(1S) transverse momentum range 6 < p(T)(Gamma(1S)) < 15GeV/c and rapidity range 2.0 < y(Gamma(1S)) < 4.5 is measured to be (20.7 +/- 5.7 +/- 2.1(-5.4)(+2.7))%, where the first uncertainty is statistical, the second is systematic and the last gives the range of the result due to the unknown Gamma(1S) and chi(b)(1P) polarizations.