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Register a new userMeasurement of boldmath $R = {mathcal{B}left(t rightarrow Wb right)/mathcal{B}left(t rightarrow Wq right)} $ in Top--Quark--Pair Decays using Dilepton Events and the Full CDF Run II Data Set
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We present a measurement of the ratio of the top-quark branching fractions $R=mathcal{B}(trightarrow Wb)/mathcal{B}(trightarrow $ $q$ represents quarks of flavors $b$, $s$, or $d$, in the final state, in events with two charged leptons, missing transverse energy and at least two jets. The measurement uses $sqrt{s}$ = 1.96 TeV proton--antiproton collision data corresponding to an integrated luminosity of 8.7 fb$^{-1}$ and collected with the Collider Detector at Fermilab during Run II of the Tevatron. We measure $R=0.87 pm 0.07$ (stat+syst), and extract the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element, $left|V_{tb}right| = 0.93 pm 0.04$ (stat+syst) assuming three generations of quarks. Under these assumptions, a lower limit of $|V_{tb}|>0.85$ at 95% credibility level is set.
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We present a measurement of the top-quark mass in events containing two leptons (electrons or muons) with a large transverse momentum, two or more energetic jets, and a transverse-momentum imbalance. We use the full proton-antiproton collision data set collected by the CDF experiment during the Fermilab Tevatron Run~II at center-of-mass energy $sqrt{s} = 1.96$ TeV, corresponding to an integrated luminosity of 9.1 fb$^{-1}$. A special observable is exploited for an optimal reduction of the dominant systematic uncertainty, associated with the knowledge of the absolute energy of the hadronic jets. The distribution of this observable in the selected events is compared to simulated distributions of ${tbar{t}}$ dilepton signal and background.We measure a value for the top-quark mass of $171.5pm 1.9~{rm (stat)}pm 2.5~{rm (syst)}$ GeV/$c^2$.
We present a measurement of the ratio of top quark branching fractions R = B(t -> Wb)/B(t -> Wq), where q can be a d, s or b quark, in the lepton+jets and dilepton ttbar final states. The measurement uses data from 5.4 fb-1 of ppbar collisions collected with the D0 detector at the Fermilab Tevatron Collider. We measure R = 0.90 +/- 0.04, and we extract the CKM matrix element |Vtb| as |Vtb| = 0.95 +/- 0.02, assuming unitarity of the 3x3 CKM matrix.
The decays $B^+rightarrow J/psi pi^+ pi^- K^+$ are studied using a data set corresponding to an integrated luminosity of 9fb$^{-1}$ collected with the LHCb detector in proton-proton collisions between 2011 and 2018. Precise measurements of the ratios of branching fractions with the intermediate $psi_2(3823)$, $chi_{c1}(3872)$ and $psi(2S)$ states are reported. The decay of $B^+rightarrow psi_2(3872)K^+$ with $psi_2(3823)rightarrow Jpsipi^+pi^-$ is observed for the first time with a significance of 5.1 standard deviations. The mass differences between the $psi_2(3823)$, $chi_{c1}(3872)$ and $psi(2S)$ states are measured to be $$ begin{array}{rcl} m_{chi_{c1(3872)}} - m_{psi_2(3823)} &= & 47.50 pm 0.53 pm 0.13,mathrm{MeV/}c^2,, m_{psi_2(3823)} - m_{psi(2S)} &= & 137.98 pm 0.53 pm 0.14,mathrm{MeV/}c^2,, m_{chi_{c1}(3872)} - m_{psi(2S)} &= & 185.49 pm 0.06 pm 0.03,mathrm{MeV/}c^2,, end{array} $$ resulting in the most precise determination of the $chi_{c1}(3782)$ mass. The width of the $psi_2(3823)$ state is found to be below 5.2MeV at 90% confidence level. The Breit-Wigner width of the $chi_{c1}(3872)$ state is measured to be $$ Gamma^{mathrm{BW}}_{chi_{c1}(3872)} = 0.96^{+0.19}_{-0.18}pm0.21 mathrm{MeV},$$ which is inconsistent with zero by 5.5 standard deviations.
Using $pp$ collision data collected by LHCb at center-of-mass energies $sqrt{s}$ = 7 TeV and 8 TeV, corresponding to an integrated luminosity of 3 fb$^{-1}$, the ratio of the branching fraction of the $B_c^+ rightarrow psi(2S)pi^+$ decay relative to that of the $B_c^+ rightarrow J/psipi^+$ decay is measured to be 0.268 $pm$ 0.032 (stat) $pm$ 0.007 (syst) $pm$ 0.006 (BF). The first uncertainty is statistical, the second is systematic, and the third is due to the uncertainties on the branching fractions of the $J/psi rightarrow mu^+mu^-$ and $psi(2S) rightarrow mu^+mu^-$ decays. This measurement is consistent with the previous LHCb result, and the statistical uncertainty is halved.
We measure the forward--backward asymmetry of the production of top quark and antiquark pairs in proton-antiproton collisions at center-of-mass energy $sqrt{s} = 1.96~mathrm{TeV}$ using the full data set collected by the Collider Detector at Fermilab (CDF) in Tevatron Run II corresponding to an integrated luminosity of $9.1~rm{fb}^{-1}$. The asymmetry is characterized by the rapidity difference between top quarks and antiquarks ($Delta y$), and measured in the final state with two charged leptons (electrons and muons). The inclusive asymmetry, corrected to the entire phase space at parton level, is measured to be $A_{text{FB}}^{tbar{t}} = 0.12 pm 0.13$, consistent with the expectations from the standard-model (SM) and previous CDF results in the final state with a single charged lepton. The combination of the CDF measurements of the inclusive $A_{text{FB}}^{tbar{t}}$ in both final states yields $A_{text{FB}}^{tbar{t}}=0.160pm0.045$, which is consistent with the SM predictions. We also measure the differential asymmetry as a function of $Delta y$. A linear fit to $A_{text{FB}}^{tbar{t}}(|Delta y|)$, assuming zero asymmetry at $Delta y=0$, yields a slope of $alpha=0.14pm0.15$, consistent with the SM prediction and the previous CDF determination in the final state with a single charged lepton. The combined slope of $A_{text{FB}}^{tbar{t}}(|Delta y|)$ in the two final states is $alpha=0.227pm0.057$, which is $2.0sigma$ larger than the SM prediction.
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