The mass of the W boson, a mediator of the weak force between elementary particles, is tightly constrained by the symmetries of the standard model of particle physics. The Higgs boson was the last missing component of the model. After observation of the Higgs boson, a measurement of the W boson mass provides a stringent test of the model. We measure the W boson mass, M W , using data corresponding to 8.8 inverse femtobarns of integrated luminosity collected in proton-antiproton collisions at a 1.96 tera–electron volt center-of-mass energy with the CDF II detector at the Fermilab Tevatron collider. A sample of approximately 4 million W boson candidates is used to obtain M W = 80 , 433.5 ± 6.4 stat ± 6.9 syst = 80 , 433.5 ± 9.4 MeV / c 2 , the precision of which exceeds that of all previous measurements combined (stat, statistical uncertainty; syst, systematic uncertainty; MeV, mega–electron volts; c , speed of light in a vacuum). This measurement is in significant tension with the standard model expectation.

At the Fermilab Tevatron proton-antiproton ($p\bar{p}$) collider, high-mass electron-neutrino ($e\nu$) pairs are produced predominantly in the process $p \bar{p} \rightarrow W(\rightarrow e\nu) + X$. The asymmetry of the electron and positron yield as a function of their pseudorapidity constrain the slope of the ratio of the $u$- to $d$-quark parton distributions versus the fraction of the proton momentum carried by the quarks. This paper reports on the measurement of the electron-charge asymmetry using the full data set recorded by the Collider Detector at Fermilab in 2001--2011 and corresponding to 9.1~fb$^{-1}$ of integrated luminosity. The measurement significantly improves the precision of the Tevatron constraints on the parton-distribution functions of the proton. Numerical tables of the measurement are provided.

The original article has been corrected.

We report an observation of new bottom baryons produced in p (cid:1) p collisions at the Tevatron. Using 1 : 1 fb (cid:2) 1 of data collected by the CDF II detector, we observe four (cid:2) 0 b (cid:1) (cid:3) resonances in the fully reconstructed decay mode (cid:2) 0 b ! (cid:2) (cid:4) c (cid:1) (cid:2) , where (cid:2) (cid:4) c ! pK (cid:2) (cid:1) (cid:4) . We interpret these states as the (cid:3) (cid:5)(cid:1)(cid:6)(cid:3) b baryons and measure the following masses: m (cid:3) (cid:4) b (cid:7) 5807 : 8 (cid:4) 2 : 0 (cid:2) 2 : 2 (cid:5) stat : (cid:6) (cid:3) 1 : 7 (cid:5) syst : (cid:6) MeV =c 2 , m (cid:3)

A. Cerrie,26 L. Cerritor ,28 Y.C. Chen, 1 M. Chertok,7 G. Chiarelli,42 G. Chlachidze, 15 K. Cho,25 D. Chokheli,13 A. Clark,18 C. Clarke, 54 M.E. Convery, 15 J. Conway, 7 M. Corboz,15 M. Cordelli,17 C.A. Cox,7 D.J. Cox, 7 M. Cremonesi, 42 D. Cruz,48 J. Cuevas y,9 R. Culbertson, 15 N. d’Ascenzov,15 M. Dattagg,15 P. de Barbaro, 45 L. Demortier,46 M. Deninno,6 M. D’Erricokk,40 F. Devoto, 21 A. Di Cantoll ,42 B. Di Ruzzap,15 J.R. Dittmann, 5 S. Donati ll ,42 M. D’Onofrio,27 M. Dorigott ,49 A. Driutti rrss,49 K. Ebina,53 R. Edgar, 32 A. Elagin,48 R. Erbacher, 7 S. Errede, 22 B. Esham, 22 R. Eusebi, 48 S. Farrington, 39

A search for the rare decay B-0 -> J/psi phi, is performed using pp collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb(-1). No significant signal of the decay is observed and an upper limit of 1.1 x 10(-7) at 90% confidence level is set on the branching fraction.

A four-body amplitude analysis of the B- -> D*(+)pi(-) pi(-) decay is performed, where fractions and relative phases of the various resonances contributing to the decay are measured. Several quasi-model-independent analyses are performed aimed at searching for the presence of new states and establishing the quantum numbers of previously observed charmed meson resonances. In particular the resonance parameters and quantum numbers are determined for the D-1 (2420), D-1 (2430), D-0 (2550), D-1* (2600), D-2 (2740) and D-3*(2750) states. The mixing between the D-1 (2420) and D-1 (2430) resonances is studied and the mixing parameters are measured. The dataset corresponds to an integrated luminosity of 4.7 fb(-1), collected in proton-proton collisions at center-of-mass energies of 7, 8 and 13 TeV with the LHCb detector.

We report four narrow peaks in the Ξ_{b}^{0}K^{-} mass spectrum obtained using pp collisions at center-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of 9  fb^{-1} recorded by the LHCb experiment. Referring to these states by their mass, the mass values are m[Ω_{b}(6316)^{-}]=6315.64±0.31±0.07±0.50  MeV, m[Ω_{b}(6330)^{-}]=6330.30±0.28±0.07±0.50  MeV, m[Ω_{b}(6340)^{-}]=6339.71±0.26±0.05±0.50  MeV, m[Ω_{b}(6350)^{-}]=6349.88±0.35±0.05±0.50  MeV, where the uncertainties are statistical, systematic, and the last is due to the knowledge of the Ξ_{b}^{0} mass. The natural widths of the three lower mass states are consistent with zero, and the 90% confidence-level upper limits are determined to be Γ[Ω_{b}(6316)^{-}]<2.8  MeV, Γ[Ω_{b}(6330)^{-}]<3.1  MeV and Γ[Ω_{b}(6340)^{-}]<1.5  MeV. The natural width of the Ω_{b}(6350)^{-} peak is 1.4_{-0.8}^{+1.0}±0.1  MeV, which is 2.5σ from zero and corresponds to an upper limit of 2.8 MeV. The peaks have local significances ranging from 3.6σ to 7.2σ. After accounting for the look-elsewhere effect, the significances of the Ω_{b}(6316)^{-} and Ω_{b}(6330)^{-} peaks are reduced to 2.1σ and 2.6σ, respectively, while the two higher mass peaks exceed 5σ. The observed peaks are consistent with expectations for excited Ω_{b}^{-} resonances.

The element vertical bar V-cb vertical bar of the Cabibbo-Kobayashi-Maskawa matrix is measured using semileptonic B-s(0) decays produced in proton-proton collision data collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb(-1). Rates of B-s0 -> D-s(-) mu(+)nu(mu) and B-s0 -> D-s*(-) mu(+)nu(mu) decays are analyzed using hadronic form-factor parametrizations derived either by Caprini, Lellouch and Neubert (CLN) or by Boyd, Grinstein and Lebed (BGL). The measured values of vertical bar V-cb vertical bar are (41.4 +/- 0.6 +/- 0.9 +/- 1.2) x 10(-3) and (42.3 +/- 0.8 +/- 0.9 +/- 1.2) x 10(-3) in the CLN and BGL parametrization, respectively. The first uncertainty is statistical, the second systematic, and the third is due to the external inputs used in the measurement. These results are in agreement with those obtained from decays of B+ and B-0 mesons. They are the first determinations of vertical bar V-cb vertical bar at a hadron-collider experiment and the first using B-s(0) meson decays.

In figure 11 of the original paper.

Using proton-proton collision data at centre-of-mass energies of s=7,8 and 13TeV recorded by the LHCb experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 9fb-1, the invariant mass spectrum of J/ψ pairs is studied. A narrow structure around 6.9GeV/c2 matching the lineshape of a resonance and a broad structure just above twice the J/ψ mass are observed. The deviation of the data from nonresonant J/ψ-pair production is above five standard deviations in the mass region between 6.2 and 7.4GeV/c2, covering predicted masses of states composed of four charm quarks. The mass and natural width of the narrow X(6900) structure are measured assuming a Breit-Wigner lineshape.

Abstract The cross-sections of $$\psi {(2S)}$$ ψ(2S) meson production in proton-proton collisions at $$\sqrt{s} =13\text { TeV} $$ s=13TeV are measured with a data sample collected by the LHCb detector corresponding to an integrated luminosity of $$275\text { pb} ^{-1} $$ 275pb-1 . The production cross-sections for prompt $$\psi {(2S)}$$ ψ(2S) mesons and those for $$\psi {(2S)}$$ ψ(2S) mesons from b-hadron decays ($${\psi {(2S)}} \text{-from- }{b} $$ ψ(2S)-from-b ) are determined as functions of the transverse momentum, $$p_{\mathrm {T}}$$ pT , and the rapidity, y, of the $$\psi {(2S)}$$ ψ(2S) meson in the kinematic range $$2

A measurement of the branching fraction of the decay B-s(0) -> (KSKS0)-K-0 is performed using proton- proton - collision data corresponding to an integrated luminosity of 5 fb(-1) collected by the LHCb experiment between 2011 and 2016. The branching fraction is determined to be B(B-s(0) -> (KSKS0)-K-0) = [8.3 +/- 1.6(stat) +/- 0.9(syst) +/- 0.8(norm) +/- 0.3(f(s)/f(d))] x 10(-6), where the first uncertainty is statistical, the second is systematic, and the third and fourth are due to uncertainties on the branching fraction of the normalization mode B-0 -> phi K-S(0) and the ratio of hadronization fractions f(s)/f(d). This is the most precise measurement of this branching fraction to date. Furthermore, a measurement of the branching fraction of the decay B-s(0) -> (KSKS0)-K-0 is performed relative to that of the B-s(0) -> (KSKS0)-K-0 channel, and is found to be B(B-s(0) -> (KSKS0)-K-0)/B(B-s(0) -> (KSKS0)-K-0) = [7.5 +/- 3.1(stat) 0.5(syst) +/- 0.3(f(s)/f(d))1 x 10(-2).

The cross-sections of $$\psi {(2S)}$$ meson production in proton-proton collisions at $$\sqrt{s} =13\text { TeV} $$ are measured with a data sample collected by the LHCb detector corresponding to an integrated luminosity of $$275\text { pb} ^{-1} $$. The production cross-sections for prompt $$\psi {(2S)}$$ mesons and those for $$\psi {(2S)}$$ mesons from b-hadron decays ($${\psi {(2S)}} \text{-from- }{b} $$) are determined as functions of the transverse momentum, $$p_{\mathrm {T}}$$, and the rapidity, y, of the $$\psi {(2S)}$$ meson in the kinematic range $$2<p_{\mathrm {T}} <20\text { GeV/}c $$ and $$2.0<y<4.5$$. The production cross-sections integrated over this kinematic region are $$\begin{aligned} \begin{aligned}&\sigma (\text{ prompt } {\psi {(2S)}},13\text { TeV})\\&\quad =1.430\pm 0.005\text { (stat)} \pm 0.099\text { (syst)} \,\upmu \text {b} ,\\&\sigma ({\psi {(2S)}} \text{-from- }{b},13\text { TeV})\\&\quad =0.426\pm 0.002\text { (stat)} \pm 0.030\text { (syst)} \,\upmu \text {b} . \end{aligned} \end{aligned}$$A new measurement of $$\psi {(2S)}$$ production cross-sections in pp collisions at $$\sqrt{s}=7\text { TeV} $$ is also performed using data collected in 2011, corresponding to an integrated luminosity of $$614\text { pb} ^{-1} $$. The integrated production cross-sections in the kinematic range $$3.5<p_{\mathrm {T}} <14\text { GeV/}c $$ and $$2.0<y<4.5$$ are $$\begin{aligned} \begin{aligned}&\sigma (\text{ prompt } {\psi {(2S)}},7\text { TeV})\\&\quad =0.471\pm 0.001\text { (stat)} \pm 0.025\text { (syst)} \,\upmu \text {b} ,\\&\sigma ({\psi {(2S)}} \text{-from- }{b},7\text { TeV})\\&\quad =0.126\pm 0.001\text { (stat)} \pm 0.008\text { (syst)} \,\upmu \text {b} . \end{aligned} \end{aligned}$$All results show reasonable agreement with theoretical calculations.

Observations are reported of different sources of CP violation from an amplitude analysis of B^{+}→π^{+}π^{+}π^{-} decays, based on a data sample corresponding to an integrated luminosity of 3  fb^{-1} of pp collisions recorded with the LHCb detector. A large CP asymmetry is observed in the decay amplitude involving the tensor f_{2}(1270) resonance, and in addition significant CP violation is found in the π^{+}π^{-}S wave at low invariant mass. The presence of CP violation related to interference between the π^{+}π^{-}S wave and the P wave B^{+}→ρ(770)^{0}π^{+} amplitude is also established; this causes large local asymmetries but cancels when integrated over the phase space of the decay. The results provide both qualitative and quantitative new insights into CP -violation effects in hadronic B decays.

Abstract The doubly Cabibbo-suppressed decay Ξ c + → pϕ with ϕ → K + K − is observed for the first time, with a statistical significance of more than fifteen standard deviations. The data sample used in this analysis corresponds to an integrated luminosity of 2 fb−1 recorded with the LHCb detector in pp collisions at a centre-of-mass energy of 8 TeV. The ratio of branching fractions between the decay Ξ c + → pϕ and the singly Cabibbo-suppressed decay Ξ c + → pK − π + is measured to be $$ \frac{\mathrm{\mathcal{B}}\left({\varXi}_c^{+}\to p\phi \right)}{\mathrm{\mathcal{B}}\left({\varXi}_c^{+}\to p{K}^{-}{\pi}^{+}\right)}=\left(19.8\pm 0.7\pm 0.9\pm 0.2\right)\times {10}^{-3}, $$ ℬ Ξ c + → p ϕ ℬ Ξ c + → p K − π + = 19.8 ± 0.7 ± 0.9 ± 0.2 × 10 − 3 , where the first uncertainty is statistical, the second systematic and the third due to the knowledge of the ϕ → K + K − branching fraction.

Bose-Einstein correlations for same-sign charged pions and kinematic b-bbar correlations in proton-proton collisions at a center-of-mass energy of 7 and 8 TeV are studied by the LHCb experiment. The dependence of Bose-Einstein correlation parameters on the charged-particle multiplicity is investigated. The correlation radius is observed to increase with multiplicity, while the chaoticity parameter decreases. The b-bbar correlations are studied using inclusive b quark decays to jpsi and are found to be in good agreement with theoretical predictions.