A search is performed for lepton-number-violating $B^-\to D^{(*)+}μ^-μ^-$ decays, using data collected by the LHCb experiment in proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb$^{-1}$. No significant signal is observed, and upper limits are set on the branching fractions, ${\cal B}(B^-\to D^{+}μ^-μ^-) < 4.6 \times 10^{-8}$ and ${\cal B}(B^-\to D^{*+}μ^-μ^-) < 5.9 \times 10^{-8}$, at the 95% confidence level.
Binned efficiencies across the Dalitz plane for $B^- \to D^{+} \mu^- \mu^-$ decay. Here $\mu_1^-$ and $\mu_2^-$ represent the two muons produced in the decay, and the index specifies their ordering in transverse momentum. Efficiencies are normalized to the average over the full simulated sample.
Binned efficiencies across the Dalitz plane for $B^- \to D^{*+} \mu^- \mu^-$ decay. Here $\mu_1^-$ and $\mu_2^-$ represent the two muons produced in the decay, and the index specifies their ordering in transverse momentum. Efficiencies are normalized to the average over the full simulated sample.
The $pp \to W^{\pm} (\to μ^{\pm} ν_μ) X$ cross-sections are measured at a proton-proton centre-of-mass energy $\sqrt{s} = 5.02$ TeV using a dataset corresponding to an integrated luminosity of 100 pb$^{-1}$ recorded by the LHCb experiment. Considering muons in the pseudorapidity range $2.2 < η< 4.4$, the cross-sections are measured differentially in twelve intervals of muon transverse momentum between $28 < p_\mathrm{T} < 52$ GeV. Integrated over $p_\mathrm{T}$, the measured cross-sections are \begin{align*} σ_{W^+ \to μ^+ ν_μ} &= 300.9 \pm 2.4 \pm 3.8 \pm 6.0~\text{pb}, \\ σ_{W^- \to μ^- \barν_μ} &= 236.9 \pm 2.1 \pm 2.7 \pm 4.7~\text{pb}, \end{align*} where the first uncertainties are statistical, the second are systematic, and the third are associated with the luminosity calibration. These integrated results are consistent with theoretical predictions. This analysis introduces a new method to determine the $W$-boson mass using the measured differential cross-sections corrected for detector effects. The measurement is performed on this statistically limited dataset as a proof of principle and yields \begin{align*} m_W = 80369 \pm 130 \pm 33~\text{MeV}, \end{align*} where the first uncertainty is experimental and the second is theoretical.
The measured differential cross sections ($d\sigma/dp_T$) for $W^+$. The first systematic uncertainty is statistical and the second is systematic.
The measured differential cross sections ($d\sigma/dp_T$) for $W^-$. The first systematic uncertainty is statistical and the second is systematic.
The correlation matrix corresponding to the statistical uncertainties on the differential cross-section ($d\sigma/dp_T$) fit results for $W^+$. To combine with $W^-$, use the rows and columns ordered as $W^+$ and then $W^-$. Assume no correlation in the statistical uncertainties between $W^+$ and $W^-$ (zero entries in the off-diagonal blocks).
We present a determination of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ from the decay $B\to D\ellν_\ell$ using a $365~\mathrm{fb}^{-1}$$e^+e^-\toΥ(4S)\to B\bar B$ data sample recorded by the Belle II experiment at the SuperKEKB collider. The semileptonic decay of one $B$ meson is reconstructed in the modes $B^0\to D^-(\to K^+π^-π^-)\ell^+ν_\ell$ and $B^+\to \bar D^0(\to K^+π^-)\ell^+ν_\ell$, where $\ell$ denotes either an electron or a muon. Charge conjugation is implied. The second $B$ meson in the $Υ(4S)$ event is not reconstructed explicitly. Using an inclusive reconstruction of the unobserved neutrino momentum, we determine the recoil variable $w=v_B\cdot v_D$, where $v_B$ and $v_D$ are the 4-velocities of the $B$ and $D$ mesons. We measure the total decay branching fractions to be $\mathcal{B}(B^0\to D^-\ell^+ν_\ell)=(2.06 \pm 0.05\,(\mathrm{stat.}) \pm 0.10\,(\mathrm{sys.}))\%$ and $\mathcal{B}(B^+\to\bar D^0\ell^+ν_\ell)=(2.31 \pm 0.04\,(\mathrm{stat.}) \pm 0.09\,(\mathrm{sys.}))\%$. We probe lepton flavor universality by measuring $\mathcal{B}(B\to Deν_e)/\mathcal{B}(B\to Dμν_μ)=1.020 \pm 0.020\,(\mathrm{stat.})\pm 0.022\,(\mathrm{sys.})$. Fitting the partial decay branching fraction as a function of $w$ and using the average of lattice QCD calculations of the $B\to D$ form factor, we obtain $ |V_{cb}|=(39.2\pm 0.4\,(\mathrm{stat.}) \pm 0.6\,(\mathrm{sys.}) \pm 0.5\,(\mathrm{th.})) \times 10^{-3}$.
Differential decay rate $d\Gamma/dw$ for $B \to D \ell \nu$ averaged over 4 modes. The uncertainty listed represents the total uncertainty from statistical and systematic sources.
Differential decay rates $d\Gamma/dw$ for individual $B \to D \ell \nu$ modes. The uncertainty listed represents the total uncertainty from statistical and systematic sources.
Correlations (stat.+syst.) between the $d\Gamma_i/dw$ bins for the averaged $B \rightarrow D \ell \nu$ spectrum (10x10). Element indices 0-9 correspond to $w$ bins: 0: [1.00, 1.06], 1: [1.06, 1.12], 2: [1.12, 1.18], 3: [1.18, 1.24], 4: [1.24, 1.30], 5: [1.30, 1.36], 6: [1.36, 1.42], 7: [1.42, 1.48], 8: [1.48, 1.54], 9: [1.54, 1.59]
A study on the Bose-Einstein correlations for triplets of same-sign pions is presented. The analysis is performed using proton-proton collisions at a centre-of-mass energy of $\sqrt{s}$ = 7 TeV, recorded by the LHCb experiment, corresponding to an integrated luminosity of 1.0 fb$^{-1}$. For the first time, the results are interpreted in the core-halo model. The parameters of the model are determined in regions of charged-particle multiplicity. This measurement provides insight into the nature of hadronisation in terms of coherence, showing a coherent emission of pions.
Results of the fit to the three-particle double ratio ($r_{d_{3}}$) for same-sign pion triplets, VELO track multiplicity for pp collision: 5-10.
Results of the fit to the three-particle double ratio ($r_{d_{3}}$) for same-sign pion triplets, VELO track multiplicity for pp collision: 11-20.
Results of the fit to the three-particle double ratio ($r_{d_{3}}$) for same-sign pion triplets, VELO track multiplicity for pp collision: 21-60.
The LHCb collaboration presents a novel suite of heavy-flavour jet substructure measurements at forward rapidity in proton-proton collisions at a centre-of-mass energy of $\sqrt{s} = 13$ TeV. The jet mass is a perturbatively calculable probe of the virtuality of hard-scattered quarks and gluons, connecting small-distance quantum chromodynamics (QCD) with long-distance experimental measurement. It becomes dominated by nonperturbative corrections at small values, presenting an excellent test of QCD across a broad range of energies. Measuring heavy-flavour jet mass with a theoretically unambiguous flavour definition for the first time probes the gluon splitting mechanism for heavy-flavour production and pushes tests of perturbative QCD to unprecedented theoretical precision. Utilising the soft drop jet-grooming technique to access the perturbative jet core further enhances constraints on first-principles theory. Measurements of the jet mass for jets containing fully reconstructed $B^\pm$ hadrons are reported with and without grooming. These results offer unparalleled tests of quark flavour and mass dependence in QCD and provide a baseline for future studies of heavy-flavour jet quenching in heavy-ion collisions.
Groomed $B^\pm$-tagged jet invariant mass $m_{\textrm{jet,gr}}/p_{\textrm{T,jet}}$ for $R=0.5$ jets reconstructed in pp data, without any WTA flavour requirement. Normalization is set to unity. $10 < p_{\textrm{T,jet}} < 12$ GeV, soft drop $z_{\textrm{cut}}=0.1, \beta=0$.
Groomed $B^\pm$-tagged jet invariant mass $m_{\textrm{jet,gr}}/p_{\textrm{T,jet}}$ for $R=0.5$ jets reconstructed in pp data, without any WTA flavour requirement. Normalization is set to unity. $12 < p_{\textrm{T,jet}} < 15$ GeV, soft drop $z_{\textrm{cut}}=0.1, \beta=0$.
Groomed $B^\pm$-tagged jet invariant mass $m_{\textrm{jet,gr}}/p_{\textrm{T,jet}}$ for $R=0.5$ jets reconstructed in pp data, without any WTA flavour requirement. Normalization is set to unity. $15 < p_{\textrm{T,jet}} < 20$ GeV, soft drop $z_{\textrm{cut}}=0.1, \beta=0$.
We present the results of a search for the charged-lepton-flavor violating decays $B^0 \rightarrow K^{*0}\tau^\pm \ell^{\mp}$, where $\ell^{\mp}$ is either an electron or a muon. The results are based on 365 fb$^{-1}$ and 711 fb$^{-1}$ datasets collected with the Belle II and Belle detectors, respectively. We use an exclusive hadronic $B$-tagging technique, and search for a signal decay in the system recoiling against a fully reconstructed $B$ meson. We find no evidence for $B^0 \rightarrow K^{*0}\tau^\pm \ell^{\mp}$ decays and set upper limits on the branching fractions in the range of $(2.9-6.4)\times10^{-5}$ at 90% confidence level.
$M_{\tau}$ distribution in signal region, (OS$e$, Belle)
$M_{\tau}$ distribution in signal region, (OS$e$, Belle II)
$M_{\tau}$ distribution in signal region, (OS$\mu$, Belle)
We present a search for the rare flavor-changing neutral-current decay $B^0 \to K^{\ast 0} τ^+ τ^-$ with data collected by the Belle II experiment at the SuperKEKB electron-positron collider. The analysis uses a 365 fb$^{-1}$ data sample recorded at the center-of-mass energy of the $Υ(4S)$ resonance. One of the $B$ mesons produced in the $Υ(4S)\to B^0 \bar{B}^0$ process is fully reconstructed in a hadronic decay mode, while its companion $B$ meson is required to decay into a $K^{\ast 0}$ and two $τ$ leptons of opposite charge. The $τ$ leptons are reconstructed in final states with a single electron, muon, charged pion or charged $ρ$ meson, and additional neutrinos. We set an upper limit on the branching ratio of $BR(B^0 \to K^{\ast 0} τ^+ τ^-) < 1.8 \times 10^{-3}$ at the 90% confidence level, which is the most stringent constraint reported to date.
- - - - - - - - Overview of HEPData Record - - - - - - - -<br/><br/></ul><b>Post-fit yields:</b><ul><li><a href="159541?version=1&table=Postfit%20yields:%20fit%20variable">Fit variable $\eta(\rm{BDT})$</a></ul><b>Signal $q^{2}$:</b><ul><li><a href="159541?version=1&table=Generated%20$q^2$"> Generated $q^{2}$ distribution </a></ul><b>Signal selection efficiency:</b><ul><li><a href="159541?version=1&table=Selection%20efficiency"> Selection efficieny in signal region </a>
Observed yields and fit results in bins of $\eta(\rm{BDT})$ as obtained by the fit on the four signal categories, corresponding to an integrated luminosity of 365 fb$^{-1}$. The yields are shown for $B^0 \rightarrow K^{\ast 0}\tau\tau$ signal and the two background components ($B\bar{B}$ decays and $q\bar{q}$ continuum).
Distribution of the di-tau invariant mass squared $q^2$ assumed for the generated signal $B^0 \rightarrow K^{\ast 0}\tau\tau$ events.
A measurement of the WZ$γ$ triboson production cross section is presented. The analysis is based on a data sample of proton-proton collisions at a center-of-mass energy of $\sqrt{s}$ = 13 TeV recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb$^{-1}$. The analysis focuses on the final state with three charged leptons, $\ell^\pmν\ell^+\ell^-$, where $\ell$ = e or $μ$, accompanied by an additional photon. The observed (expected) significance of the WZ$γ$ signal is 5.4 (3.8) standard deviations. The cross section is measured in a fiducial region, where events with an $\ell$ originating from a tau lepton decay are excluded, to be 5.48 $\pm$ 1.11 fb, which is compatible with the prediction of 3.69 $\pm$ 0.24 fb at next-to-leading order in quantum chromodynamics. Exclusion limits are set on anomalous quartic gauge couplings and on the production cross sections of massive axion-like particles.
The distributions of the variables used in the simultaneous fit for the nonprompt $l$ CR. The black points with error bars represent the data and their statistical uncertainties, whereas the shaded band represents the predicted uncertainties. The bottom panel in each figure shows the ratio of the number of events observed in data to that of the total SM prediction. The last bin of each plot has been extended to include the overflow contribution.
The distributions of the variables used in the simultaneous fit for the nonprompt $\gamma$ CR. The black points with error bars represent the data and their statistical uncertainties, whereas the shaded band represents the predicted uncertainties. The bottom panel in each figure shows the ratio of the number of events observed in data to that of the total SM prediction. The last bin of each plot has been extended to include the overflow contribution.
The distributions of the variables used in the simultaneous fit for the ZZ CR. The black points with error bars represent the data and their statistical uncertainties, whereas the shaded band represents the predicted uncertainties. The bottom panel in each figure shows the ratio of the number of events observed in data to that of the total SM prediction. The last bin of each plot has been extended to include the overflow contribution.
A search for $t$-channel exchange of leptoquarks (LQs) is performed in dimuon and dielectron spectra using proton-proton collision data collected at $\sqrt{s}$ = 13 TeV with the CMS detector at the CERN LHC. The data correspond to an integrated luminosity of 138 fb$^{-1}$. Eight scenarios are considered, in which scalar or vector LQs couple up or down quarks to muons or electrons, for dilepton invariant masses above 500 GeV. The LQ masses are probed up to 5 TeV, beyond a regime probed by previous pair-production and single-production searches. The differential distributions of dilepton events are fit to templates that model the nonresonant LQ exchange and various standard model background processes. Limits are set on LQ-fermion coupling strengths for scalar and vector LQ masses in the 1-5 TeV range at 95% confidence level, establishing stringent limits on first- and second-generation LQs.
Observed and Expected UL exclusions on the $BR(H\to SUEP)$ of hadronic signals with $m_{A'} = 0.7\;GeV$ and $BR(A' \rightarrow ee) = BR(A' \rightarrow \mu\mu) = 0.15$ and $BR(A' \rightarrow \pi\pi) = 0.7$.
The observed data in the dielectron channel and the fitted signal-plus-background templates, shown for the $S_{e u}$ scenario with a candidate LQ mass of 2.5 TeV. Distributions of events are binned in the reconstructed dilepton mass, rapidity, and cosine theta.
Observed and Expected UL exclusions on the $BR(H\to S)$ of leptonic signals with $m_{A'} = 0.5\;GeV$ and $BR(A' \rightarrow ee) = BR(A' \rightarrow \mu\mu) = 0.2$ and $BR(A' \rightarrow \pi\pi) = 0.6$.
Measurements are presented of the cross-section for the central exclusive production of $J/\psi\to\mu^+\mu^-$ and $\psi(2S)\to\mu^+\mu^-$ processes in proton-proton collisions at $\sqrt{s} = 13 $ TeV with 2016-2018 data. They are performed by requiring both muons to be in the LHCb acceptance (with pseudorapidity $2<\eta_{\mu^\pm} < 4.5$) and mesons in the rapidity range $2.0 < y < 4.5$. The integrated cross-section results are \begin{equation*} \sigma_{J/\psi\to\mu^+\mu^-}(2.0<y_{J/\psi}<4.5,2.0<\eta_{\mu^\pm} < 4.5) = 400 \pm 2 \pm 5 \pm 12 \,{\rm pb}\,, \end{equation*}\begin{equation*} \sigma_{\psi(2S)\to\mu^+\mu^-}(2.0<y_{\psi(2S)}<4.5,2.0<\eta_{\mu^\pm} < 4.5) = 9.40 \pm 0.15 \pm 0.13 \pm 0.27 \,{\rm pb}\,, \end{equation*} where the uncertainties are statistical, systematic and due to the luminosity determination. In addition, a measurement of the ratio of $\psi(2S)$ and $J/\psi$ cross-sections, at an average photon-proton centre-of-mass energy of 1 TeV, is performed, giving \begin{equation*} \frac{\sigma_{\psi(2S)}}{\sigma_{J/\psi}} = 0.1763 \pm 0.0029 \pm 0.0008 \pm 0.0039 \,, \end{equation*} where the first uncertainty is statistical, the second systematic and the third due to the knowledge of the involved branching fractions. For the first time, the dependence of the $J/\psi$ and $\psi(2S)$ cross-sections on the total transverse momentum transfer is determined in $pp$ collisions and is found consistent with the behaviour observed in electron-proton collisions.
Differential CEP $J/\psi\to\mu^+\mu^-$ cross-sections corrected for efficiency, acceptance and branching fraction. The systematic uncertainties are split between those uncorrelated across $y$ ranges, those that are 100% correlated and the luminosity uncertainty.
Differential CEP $\psi(2S)\to\mu^+\mu^-$ cross-sections corrected for efficiency, acceptance and branching fraction. The systematic uncertainties are split between those uncorrelated across $y$ ranges, those that are 100% correlated and the luminosity uncertainty.
Ratio of differential CEP $\psi(2S)\to\mu^+\mu^-$ to $J/\psi\to\mu^+\mu^-$ cross-sections corrected for efficiency, acceptance and branching fraction. The systematic uncertainties are split between those uncorrelated across $y$ ranges, those that are 100% correlated.
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