arXiv subjects

L. J. Bel

Publications and source records attributed to L. J. Bel.

276 records · Page 16Linked to original sources

arXiv2015

Identification of beauty and charm quark jets at LHCb

Identification of jets originating from beauty and charm quarks is important for measuring Standard Model processes and for searching for new physics. The performance of algorithms developed to select $b$- and $c$-quark jets is measured using data recorded by LHCb from proton-proton collisions at $\sqrt{s}=7$ TeV in 2011 and at $\sqrt{s}=8$ TeV in 2012. The efficiency for identifying a $b(c)$ jet is about 65%(25%) with a probability for misidentifying a light-parton jet of 0.3% for jets with transverse momentum $p_{\rm T} > 20$ GeV and pseudorapidity $2.2 < η< 4.2$. The dependence of the performance on the $p_{\rm T}$ and $η$ of the jet is also measured.

hep-ex↗

arXiv2015

First observation and measurement of the branching fraction for the decay $B^0_s \to D_s^{*\mp} K^{\pm}$

The first observation of the $B^0_s \to D_s^{*\mp} K^{\pm}$ decay is reported using 3.0$fb^{-1}$ of proton-proton collision data collected by the LHCb experiment. The $D_s^{*\mp}$ mesons are reconstructed through the decay chain $D_s^{*\mp} \to γD_s^{\mp}(K^{\mp}K^{\pm}π^{\mp})$. The branching fraction relative to that for $B^0_s \to D_s^{*-} π^{+}$ is measured to be $0.068 \pm 0.005 ^{+0.003}_{-0.002}$, where the first uncertainty is statistical and the second is systematic. Using a recent measurement of $BR(B^0_s \to D_s^{*-} π^{+})$ the absolute branching fraction of $B^0_s \to D_s^{*\mp} K^{\pm}$ is measured as ( 16.3 $\pm$ 1.2 (stat) $^{+0.7}_{-0.5}$ (syst) $\pm$ 4.8 (norm) ) $\times$ 10$^{-5}$, where the third uncertainty is due to the uncertainty on the branching fraction of the normalisation channel.

hep-ex↗

arXiv2015

Measurement of the time-dependent CP asymmetries in $B_s^0\rightarrow J/ψK_{\rm S}^0$

The first measurement of decay-time-dependent CP asymmetries in the decay $B_s^0\rightarrow J/ψK_{\rm S}^0$ and an updated measurement of the ratio of branching fractions $\mathcal{B}(B_s^0\rightarrow J/ψK_{\rm S}^0)/\mathcal{B}(B_d^0\rightarrow J/ψK_{\rm S}^0)$} are presented. The results are obtained using data corresponding to an integrated luminosity of 3.0 fb$^{-1}$ of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of 7 and 8 TeV. The results on the CP asymmetries are $A_{ΔΓ}(B_s^0\rightarrow J/ψK_{\rm S}^0) = 0.49_{-0.65}^{+0.77}(stat) \pm 0.06(syst)$, $C_{\rm dir}(B_s^0\rightarrow J/ψK_{\rm S}^0) = -0.28 \pm 0.41(stat) \pm 0.08(syst)$ and $S_{\rm mix}(B_s^0\rightarrow J/ψK_{\rm S}^0) = -0.08 \pm 0.40(stat) \pm 0.08(syst)$. The ratio $\mathcal{B}(B_s^0\rightarrow J/ψK_{\rm S}^0)/\mathcal{B}(B_d^0\rightarrow J/ψK_{\rm S}^0)$ is measured to be $0.0431 \pm 0.0017(stat) \pm 0.0012(syst) \pm 0.0025(f_s/f_d)$, where the last uncertainty is due to the knowledge of the $B_s^0$ and $B_d^0$ production fractions.

hep-ex↗

arXiv2015

A study of $CP$ violation in $B^\mp \rightarrow Dh^\mp$ ($h=K,π$) with the modes $D \rightarrow K^\mp π^\pm π^0$, $D \rightarrow π^+π^-π^0$ and $D \rightarrow K^+K^-π^0$

An analysis of the decays of $B^\mp \rightarrow D K^\mp$ and $B^\mp \rightarrow D π^\mp $ is presented in which the $D$ meson is reconstructed in the three-body final states $K^\mp π^\pm π^0$, $π^+ π^- π^0$ and $K^+ K^- π^0$. Using data from LHCb corresponding to an integrated luminosity of 3.0 fb$^{-1}$ of $pp$ collisions, measurements of several $CP$ observables are performed. First observations are obtained of the suppressed ADS decay $B^\mp \rightarrow [π^\mp K^\pm π^0]_D π^\mp$ and the quasi-GLW decay $B^\mp \rightarrow [K^+ K^- π^0]_D π^\mp$. The results are interpreted in the context of the unitarity triangle angle $γ$ and related parameters.

hep-ex↗

arXiv2015

Measurement of $CP$ violation in $B^0 \rightarrow J/ψK^0_S$ decays

Measurements are presented of the $CP$ violation observables $S$ and $C$ in the decays of $B^0$ and $\overline{B}{}^0$ mesons to the $J/ψK^0_S$ final state. The data sample corresponds to an integrated luminosity of $3.0\,\text{fb}^{-1}$ collected with the LHCb experiment in proton-proton collisions at center-of-mass energies of $7$ and $8\,\text{TeV}$. The analysis of the time evolution of $41500$ $B^0$ and $\overline{B}{}^0$ decays yields $S = 0.731 \pm 0.035 \, \text{(stat)} \pm 0.020 \,\text{(syst)}$ and $C = -0.038 \pm 0.032 \, \text{(stat)} \pm 0.005\,\text{(syst)}$. In the Standard Model, $S$ equals $\sin(2β)$ to a good level of precision. The values are consistent with the current world averages and with the Standard Model expectations.

hep-ex↗

arXiv2014

Determination of the branching fractions of $B_{s}^{0} \to D_{s}^{\mp} K^{\pm}$ and $B^{0} \to D_{s}^{-} K^{+}$

Measurements are presented of the branching fractions of the decays $B_{s}^{0} \to D_{s}^{\mp} K^{\pm}$ and $B^{0} \to D_{s}^{-} K^{+}$ relative to the decays $B_{s}^{0} \to D_{s}^{-} π^{+}$ and $B^{0} \to D^{-} π^{+}$, respectively. The data used correspond to an integrated luminosity of 3.0 fb$^{-1}$ of proton-proton collisions. The ratios of branching fractions are $\dfrac{\mathcal{B}(B_{s}^{0} \to D_{s}^{\mp} K^{\pm})}{\mathcal{B}(B_{s}^{0} \to D_{s}^{-} π^{+})} = 0.0752 \pm 0.0015 \pm 0.0019$ and $\dfrac{\mathcal{B}(B^{0} \to D_{s}^{-} K^{+})}{\mathcal{B}(B^{0} \to D^{-} π^{+})} = 0.0129 \pm 0.0005 \pm 0.0008,$ where the uncertainties are statistical and systematic, respectively.

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