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Register a new userPrecise measurement of the $f_s/f_d$ ratio of fragmentation fractions and of $B^0_s$ decay branching fractions
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The ratio of the $B^0_s$ and $B^0$ fragmentation fractions, $f_s/f_d$, in proton-proton collisions at the LHC, is obtained as a function of $B$-meson transverse momentum and collision centre-of-mass energy from the combined analysis of different $B$-decay channels measured by the LHCb experiment. The results are described by a linear function of the meson transverse momentum, or with a function inspired by Tsallis statistics. Precise measurements of the branching fractions of the $B^0_s to J/psi phi$ and $B^0_s to D^-_s pi^+$ decays are performed, reducing their uncertainty by about a factor of two with respect to previous world averages. Numerous $B^0_s$ decay branching fractions, measured at the LHCb experiment, are also updated using the new values of $f_s/f_d$ and branching fractions of normalisation channels. These results reduce a major source of systematic uncertainty in several searches for new physics performed through measurements of $B^0_s$ branching fractions.
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Using 482 pb$^{-1}$ of data taken at $sqrt{s}=4.009$ GeV, we measure the branching fractions of the decays of $D^{*0}$ into $D^0pi^0$ and $D^0gamma$ to be $BR(D^{*0} to D^0pi^0)=(65.5pm 0.8pm 0.5)%$ and $BR(D^{*0} to D^0gamma)=(34.5pm 0.8pm 0.5)%$ respectively, by assuming that the $D^{*0}$ decays only into these two modes. The ratio of the two branching fractions is $BR(D^{*0} to D^0pi^0)/BR(D^{*0} to D^0gamma) =1.90pm 0.07pm 0.05$, which is independent of the assumption made above. The first uncertainties are statistical and the second ones systematic. The precision is improved by a factor of three compared to the present world average values.
The ratio of charged and neutral B meson production at the Upsilon(4S), f_{+-}/f_{00}, is measured through the decays B bar -> D* l- nu_l bar, reconstructed using a partial reconstruction method where the D* is detected only through a pion daughter from the decay D* -> D pi. Using data collected by the CLEO II detector, the charged and neutral B decays are measured in such a way that their ratio is independent of decay model, limited mainly by the uncertainty in the relative efficiency for detecting neutral and charged pions. This measurement yields the ratio of production fractions times the ratio of semileptonic branching fractions, f_{+-}b_{+}/f_{00}b_0. Assuming that b_+/b_0 is equal to the lifetime ratio tau_+/tau_0 and using the world average value of tau_+/tau_0 as input, we obtain f_{+-}/f_{00}=1.058+- 0.084+- 0.136.
First evidence of the $B^0to J/psiomega$ decay is found and the $B_{s}^0to J/psieta$ and $B_{s}^0to J/psieta^{prime}$ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 $mathrm{fb}^{-1}$ collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of $sqrt{s} = 7$ TeV. The branching fractions of these decays are measured relative to that of the $mathrm{B}^0to J/psirho^0$ decay: $$frac{Br(B^0to J/psiomega)}{Br(B^0to J/psirho^0)} = 0.89 pm0.19(stat)^{+0.07}_{-0.13}(syst)$$ $$frac{Br(B^0_sto J/psieta)}{Br(B^0to J/psirho^0)} = 14.0 pm 1.2(stat)^{+1.1}_{-1.5}(syst)^{+1.1}_{-1.0}(frac{f_d}{f_s}),$$ $$frac{Br(B^0_sto J/psieta^{prime})}{Br(B^0to J/psirho^0)} = 12.7pm1.1(stat)^{+0.5}_{-1.3}(syst)^{+1.0}_{-0.9}(frac{f_d}{f_s}),$$ where the last uncertainty is due to the knowledge of $f_d/f_s$, the ratio of b-quark hadronization factors that accounts for the different production rate of $B^0$ and $B^0_s$ mesons. The ratio of the branching fractions of $B^0_sto J/psieta^{prime}$ and $B^0_sto J/psieta$ decays is measured to be $$ frac{Br(B^0_sto J/psieta^{prime})}{Br(B^0_sto J/psieta)} = 0.90pm0.09(stat)^{+0.06}_{-0.02}(syst).$$
The first observation of the decay $bar{B}^0_s to D^0 K^{*0}$ using $pp$ data collected by the LHCb detector at a centre-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 36 pb$^{-1}$, is reported. A signal of $34.4 pm 6.8$ events is obtained and the absence of signal is rejected with a statistical significance of more than nine standard deviations. The $bar{B}^0_s to D^0 K^{*0}$ branching fraction is measured relative to that of $bar{B}^0 to D^0 rho^0$: $frac{{cal B}(bar{B}^0_s to D^0 K^{*0})}{{cal B}(bar{B}^0 to D^0 rho^0)} = 1.48 pm 0.34 pm 0.15 pm 0.12$, where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the ratio of the $B^0$ and $B^0_s$ hadronisation fractions.
Using the data accumulated in 2002-2004 with the DO detector in proton-antiproton collisions at the Fermilab Tevatron collider with centre-of-mass energy 1.96 TeV, the branching fractions of the decays B -> bar{D}_1^0(2420) mu^+ u_mu X and B -> bar{D}_2^{*0}(2460) mu^+ u_mu X and their ratio have been measured: BR(bar{b}->B) cdot BR(B-> bar{D}_1^0 mu^+ u_mu X) cdot BR(bar{D}_1^0 -> D*- pi+) = (0.087+-0.007(stat)+-0.014(syst))%; BR(bar{b}->B)cdot BR(B->D_2^{*0} mu^+ u_mu X) cdot BR(bar{D}_2^{*0} -> D*- pi^+) = (0.035+-0.007(stat)+-0.008(syst))%; and (BR(B -> bar{D}_2^{*0} mu^+ u_mu X)BR(D2*0->D*- pi+)) / (BR(B -> bar{D}_1^{0} mu^+ u_mu X)cdot BR(bar{D}_1^{0}->D*- pi^+)) = 0.39+-0.09(stat)+-0.12(syst), where the charge conjugated states are always implied.
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