We present a measurement of the W boson mass in W-->e(nu) decays using 1 fb-1 of data collected with the D0 detector during Run II of the Fermilab Tevatron collider. With a sample of 499830 W-->e(nu) candidate events, we measure M(W)=80.401+/-0.043 GeV. This is the most precise measurement from a single experiment.
Using a data sample of $$\sqrt{s}=13\,\text {TeV}$$ proton-proton collisions collected by the CMS experiment at the LHC in 2017 and 2018 with an integrated luminosity of $$103\text {~fb}^{-1}$$ , the $$\text {B}^{0}_{\mathrm{s}} \rightarrow \uppsi (\text {2S})\text {K}_\mathrm{S}^{0}$$ and $$\text {B}^{0} \rightarrow \uppsi (\text {2S})\text {K}_\mathrm{S}^{0} \uppi ^+\uppi ^-$$ decays are observed with significances exceeding 5 standard deviations. The resulting branching fraction ratios, measured for the first time, correspond to $${\mathcal {B}}(\text {B}^{0}_{\mathrm{s}} \rightarrow \uppsi (\text {2S})K_\mathrm{S}^{0})/{\mathcal {B}}(\text {B}^{0}\rightarrow \uppsi (\text {2S})K_\mathrm{S}^{0}) = (3.33 \pm 0.69 (\text {stat})\, \pm 0.11\,(\text {syst}) \pm 0.34\,(f_{\mathrm{s}}/f_{\mathrm{d}})) \times 10^{-2}$$ and $${\mathcal {B}}(\text {B}^{0} \rightarrow \uppsi (\text {2S})\text {K}_\mathrm{S}^{0} \uppi ^{+} \uppi ^{-})/ {\mathcal {B}}(\text {B}^{0} \rightarrow \uppsi (\text {2S})\text {K}^{0}_{\mathrm{S}}) = 0.480 \pm 0.013\,(\text {stat}) \pm 0.032\,(\text {syst})$$ , where the last uncertainty in the first ratio is related to the uncertainty in the ratio of production cross sections of $$\hbox {B}^{0}_{\mathrm{s}}$$ and $$\hbox {B}^{0}$$ mesons, $$f_{\mathrm{s}}/f_{\mathrm{d}}$$ .
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.
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
We report on a search for a spin-zero non-standard model particle in proton-antiproton collisions collected by the Collider Detector at Fermilab at a center-of-mass-energy of 1.96 TeV. This particle, the phi boson, is expected to decay into a bottom-antibottom quark pair and to be produced in association with at least one bottom quark. The data sample consists of events with three jets identified as initiated by bottom quarks and corresponds to 5.4 fb(-1) of integrated luminosity. In each event, the invariant mass of the two most energetic jets is studied by looking for deviations from the multijet background, which is modeled using data. No evidence is found for such a particle. Exclusion upper limits ranging from 20 to 2 pb are set for the product of production cross sections times branching fraction for the hypothetical phi boson with mass between 100 and 300 GeV/c(2). These are the most stringent constraints to date.
A search has been performed for heavy resonances decaying to ZZ or ZW in 2 ℓ 2q final states, with two charged leptons ( ℓ = e , μ ) produced by the decay of a Z boson, and two quarks produced by the decay of a W or Z boson. The analysis is sensitive to resonances with masses in the range from 400 to 4500 GeV. Two categories are defined based on the merged or resolved reconstruction of the hadronically decaying vector boson, optimized for high- and low-mass resonances, respectively. The search is based on data collected during 2016 by the CMS experiment at the LHC in proton-proton collisions with a center-of-mass energy of √(s)=13 TeV, corresponding to an integrated luminosity of 35.9 fb −1 . No excess is observed in the data above the standard model background expectation. Upper limits on the production cross section of heavy, narrow spin-1 and spin-2 resonances are derived as a function of the resonance mass, and exclusion limits on the production of W ′ bosons and bulk graviton particles are calculated in the framework of the heavy vector triplet model and warped extra dimensions, respectively.
Measurements are presented of the lifetimes of the B 0 , B s 0 , Λ b 0 , and B c + hadrons using the decay channels B 0 → J / ψ K ∗ ( 892 ) 0 , B 0 → J / ψ K S 0 , B s 0 → J / ψ π + π - , B s 0 → J / ψ ϕ ( 1020 ) , Λ b 0 → J / ψ Λ 0 , and B c + → J / ψ π + . The data sample, corresponding to an integrated luminosity of 19.7 fb -1 , was collected by the CMS detector at the LHC in proton-proton collisions at s = 8 TeV . The B 0 lifetime is measured to be 453.0 ± 1.6 (stat) ± 1.8 (syst) μ m in J / ψ K ∗ ( 892 ) 0 and 457.8 ± 2.7 (stat) ± 2.8 (syst) μ m in J / ψ K S 0 , which results in a combined measurement of c τ B 0 = 454.1 ± 1.4 (stat) ± 1.7 (syst) μ m . The effective lifetime of the B s 0 meson is measured in two decay modes, with contributions from different amounts of the heavy and light eigenstates. This results in two different measured lifetimes: c τ B s 0 → J / ψ π + π - = 502.7 ± 10.2 (stat) ± 3.4 (syst) μ m and c τ B s 0 → J / ψ ϕ ( 1020 ) = 443.9 ± 2.0 (stat) ± 1.5 (syst) μ m . The Λ b 0 lifetime is found to be 442.9 ± 8.2 (stat) ± 2.8 (syst) μ m . The precision from each of these channels is as good as or better than previous measurements. The B c + lifetime, measured with respect to the B + to reduce the systematic uncertainty, is 162.3 ± 7.8 (stat) ± 4.2 (syst) ± 0.1 ( τ B + ) μ m . All results are in agreement with current world-average values.
A search for new physics in events with a Z boson produced in association with large missing transverse momentum at the LHC is presented. The search is based on the 2016 data sample of proton-proton collisions recorded with the CMS experiment at s = 13 TeV , corresponding to an integrated luminosity of 35.9 fb - 1 . The results of this search are interpreted in terms of a simplified model of dark matter production via spin-0 or spin-1 mediators, a scenario with a standard-model-like Higgs boson produced in association with the Z boson and decaying invisibly, a model of unparticle production, and a model with large extra spatial dimensions. No significant deviations from the background expectations are found, and limits are set on relevant model parameters, significantly extending the results previously achieved in this channel.
A search for standard model production of four top quarks ( t t ¯ t t ¯ ) is reported using events containing at least three leptons ( e , μ ) or a same-sign lepton pair. The events are produced in proton-proton collisions at a center-of-mass energy of 13 TeV at the LHC, and the data sample, recorded in 2016, corresponds to an integrated luminosity of 35.9 fb - 1 . Jet multiplicity and flavor are used to enhance signal sensitivity, and dedicated control regions are used to constrain the dominant backgrounds. The observed and expected signal significances are, respectively, 1.6 and 1.0 standard deviations, and the t t ¯ t t ¯ cross section is measured to be 16 . 9 - 11.4 + 13.8 fb , in agreement with next-to-leading-order standard model predictions. These results are also used to constrain the Yukawa coupling between the top quark and the Higgs boson to be less than 2.1 times its expected standard model value at 95% confidence level.
Four-lepton production in proton-proton collisions, , where or , is studied at a center-of-mass energy of 13 with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 35.9. The ZZ production cross section, , measured using events with two opposite-sign, same-flavor lepton pairs produced in the mass region , is consistent with standard model predictions. Differential cross sections are measured and are well described by the theoretical predictions. The Z boson branching fraction to four leptons is measured to be for events with a four-lepton invariant mass in the range and a dilepton mass for all opposite-sign, same-flavor lepton pairs. The results agree with standard model predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous ZZZ and ZZ couplings at 95% confidence level: , , , .
A search is reported for heavy resonances decaying into e μ final states in proton-proton collisions recorded by the CMS experiment at the CERN LHC at √(s)=13 TeV, corresponding to an integrated luminosity of 35.9 fb −1 . The search focuses on resonance masses above 200 GeV. With no evidence found for physics beyond the standard model in the e μ mass spectrum, upper limits are set at 95
Article history: Received 28 August 2017 Received in revised form 14 November 2017 Accepted 2 December 2017 Available online 6 December 2017 Editor: M. Doser
The nuclear modification factors of J / ψ and ψ (2S) mesons are measured in PbPb collisions at a centre-of-mass energy per nucleon pair of s NN = 5.02 TeV . The analysis is based on PbPb and p p data samples collected by CMS at the LHC in 2015, corresponding to integrated luminosities of 464 μ b - 1 and 28 pb -1 , respectively. The measurements are performed in the dimuon rapidity range of | y | 2.4 as a function of centrality, rapidity, and transverse momentum ( p T ) from p T = 3 GeV / c in the most forward region and up to 50 GeV / c . Both prompt and nonprompt (coming from b hadron decays) J / ψ mesons are observed to be increasingly suppressed with centrality, with a magnitude similar to the one observed at s NN = 2.76 TeV for the two J / ψ meson components. No dependence on rapidity is observed for either prompt or nonprompt J / ψ mesons. An indication of a lower prompt J / ψ meson suppression at p T \u003e 25 GeV / c is seen with respect to that observed at intermediate p T . The prompt ψ (2S) meson yield is found to be more suppressed than that of the prompt J / ψ mesons in the entire p T range.
Abstract A search for heavy resonances decaying to a pair of Z bosons is performed using data collected with the CMS detector at the LHC. Events are selected by requiring two oppositely charged leptons (electrons or muons), consistent with the decay of a Z boson, and large missing transverse momentum, which is interpreted as arising from the decay of a second Z boson to two neutrinos. The analysis uses data from proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1. The hypothesis of a spin-2 bulk graviton (X) decaying to a pair of Z bosons is examined for 600 ≤ m X ≤ 2500 GeV and upper limits at 95% confidence level are set on the product of the production cross section and branching fraction of X → ZZ ranging from 100 to 4 fb. For bulk graviton models characterized by a curvature scale parameter $$ \tilde{k}=0.5 $$ k ˜ = 0.5 in the extra dimension, the region m X < 800 GeV is excluded, providing the most stringent limit reported to date. Variations of the model considering the possibility of a wide resonance produced exclusively via gluon-gluon fusion or $$ \mathrm{q}\overline{\mathrm{q}} $$ q q ¯ annihilation are also examined.