A search for lepton flavour violating decays of the Higgs boson in the $\mu\tau$ and e$\tau$ decay modes is presented. The search is based on a data set corresponding to an integrated luminosity of 35.9 fb$^{-1}$ of proton-proton collisions collected with the CMS detector in 2016, at a centre-of-mass energy of 13 TeV. No significant excess over the standard model expectation is observed. The observed (expected) upper limits on the lepton flavour violating branching fractions of the Higgs boson are $\mathcal{B}$(H$\to\mu\tau$) < 0.25% (0.25%) and $\mathcal{B}$(H$\to$e$\tau$) < 0.61% (0.37%), at 95% confidence level. These results are used to derive upper limits on the off-diagonal $\mu\tau$ and e$\tau$ Yukawa couplings $\sqrt{|{Y_{\mu\tau}}|^{2}+|{Y_{\tau\mu}}|^{2}} < 1.43 \times 10^{-3}$ and $\sqrt{|{Y_{\mathrm{e}\tau}}|^{2}+|{Y_{\tau\mathrm{e}}}|^{2}} < 2.26 \times 10^{-3}$ at 95% confidence level. The limits on the lepton flavour violating branching fractions of the Higgs boson and on the associated Yukawa couplings are the most stringent to date.
Expected and observed 95 percent CL upper limits on BR(H to mu tau) for each individual category and combined from BDT fit analysis
Expected and observed 95 percent CL upper limits on BR(H to mu tau) for each individual category and combined from collinear mass fit analysis
Expected and observed 95 percent CL upper limits on BR(H to e tau) for each individual category and combined from BDT fit analysis
A search for resonance-like structures in the $\mathrm{B}^{0}_{\mathrm{s}}\pi^{\pm}$ invariant mass spectrum is performed using proton-proton collision data collected by the CMS experiment at the LHC at $\sqrt{s} = $ 8 TeV, corresponding to an integrated luminosity of 19.7 fb$^{-1}$. The $\mathrm{B}^{0}_{\mathrm{s}}$ mesons are reconstructed in the decay chain $\mathrm{B}^{0}_{\mathrm{s}} \rightarrow \mathrm{J}/\psi\,\phi$, with $\mathrm{J}/\psi \rightarrow \mu^+\mu^-$ and $\phi\rightarrow\mathrm{K^{+}}\mathrm{K^{-}}$. The $\mathrm{B}^{0}_{\mathrm{s}}\pi^{\pm}$ invariant mass distribution shows no statistically significant peaks for different selection requirements on the reconstructed $\mathrm{B}^{0}_{\mathrm{s}}$ and $\pi^{\pm}$ candidates. Upper limits are set on the relative production rates of the X(5568) and $\mathrm{B}^{0}_{\mathrm{s}}$ states times the branching fraction of the decay $\mathrm{X}(5568)^{\pm} \rightarrow \mathrm{B}^{0}_{\mathrm{s}} \pi^{\pm} $. In addition, upper limits are obtained as a function of the mass and the natural width of possible exotic states decaying into $\mathrm{B}^{0}_{\mathrm{s}}\pi^{\pm}$.
Upper limit of the relative production of the X(5568) decaying to $B^s \pi^\pm$, with respect to the inclusive $B^0_s$ production.
The TOTEM experiment at the LHC has performed the first measurement at $\sqrt{s} = 13$ TeV of the $\rho$ parameter, the real to imaginary ratio of the nuclear elastic scattering amplitude at $t=0$, obtaining the following results: $\rho = 0.09 \pm 0.01$ and $\rho = 0.10 \pm 0.01$, depending on different physics assumptions and mathematical modelling. The unprecedented precision of the $\rho$ measurement, combined with the TOTEM total cross-section measurements in an energy range larger than 10 TeV (from 2.76 to 13 TeV), has implied the exclusion of all the models classified and published by COMPETE. The $\rho$ results obtained by TOTEM are compatible with the predictions, from alternative theoretical models both in the Regge-like framework and in the QCD framework, of a colourless 3-gluon bound state exchange in the $t$-channel of the proton-proton elastic scattering. On the contrary, if shown that the 3-gluon bound state $t$-channel exchange is not of importance for the description of elastic scattering, the $\rho$ value determined by TOTEM would represent a first evidence of a slowing down of the total cross-section growth at higher energies. The very low-$|t|$ reach allowed also to determine the absolute normalisation using the Coulomb amplitude for the first time at the LHC and obtain a new total proton-proton cross-section measurement $\sigma_{tot} = 110.3 \pm 3.5$ mb, completely independent from the previous TOTEM determination. Combining the two TOTEM results yields $\sigma_{tot} = 110.5 \pm 2.4$ mb.
Differential cross-section.
Azimuthal correlations between the two jets with the largest transverse momenta $ {p_{\mathrm{T}}} $ in inclusive 2-, 3-, and 4-jet events are presented for several regions of the leading jet $ {p_{\mathrm{T}}} $ up to 4 TeV. For 3- and 4-jet scenarios, measurements of the minimum azimuthal angles between any two of the three or four leading $ {p_{\mathrm{T}}} $ jets are also presented. The analysis is based on data from proton-proton collisions collected by the CMS Collaboration at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. Calculations based on leading-order matrix elements supplemented with parton showering and hadronization do not fully describe the data, so next-to-leading-order calculations matched with parton shower and hadronization models are needed to better describe the measured distributions. Furthermore, we show that azimuthal jet correlations are sensitive to details of the parton showering, hadronization, and multiparton interactions. A next-to-leading-order calculation matched with parton showers in the MC@NLO method, as implemented in HERWIG 7, gives a better overall description of the measurements than the POWHEG method.
Normalized inclusive 2-jet cross section differential in $\Delta\phi_{1,2}$ for $200 < p_{T}^{max} < 300$ GeV
Normalized inclusive 2-jet cross section differential in $\Delta\phi_{1,2}$ for $300 < p_{T}^{max} < 400$ GeV
Normalized inclusive 2-jet cross section differential in $\Delta\phi_{1,2}$ for $400 < p_{T}^{max} < 500$ GeV
A measurement is presented of the associated production of a single top quark and a Z boson. The study uses data from proton-proton collisions at $\sqrt{s} =$ 13 TeV recorded by the CMS experiment, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. Using final states with three leptons (electrons or muons), the tZq production cross section is measured to be $\sigma$(pp$\to$tZq$\to$Wb$\ell^+\ell^-$q) = $123 ^{+33}_{-31}$ (stat) $^{+29}_{-23}$ (syst) fb, where $\ell$ stands for electrons, muons, or $\tau$ leptons, with observed and expected significances of 3.7 and 3.1 standard deviations, respectively.
The measured cross section, with statistical and systematic uncertainties. The observed significance. The expected significance
A first search for same-sign WW production via double-parton scattering is performed based on proton-proton collision data at a center-of-mass energy of 8 TeV using dimuon and electron-muon final states. The search is based on the analysis of data corresponding to an integrated luminosity of 19.7 fb$^{-1}$. No significant excess of events is observed above the expected single-parton scattering yields. A 95% confidence level upper limit of 0.32 pb is set on the inclusive cross section for same-sign WW production via the double-parton scattering process. This upper limit is used to place a 95% confidence level lower limit of 12.2 mb on the effective double-parton cross section parameter, closely related to the transverse distribution of partons in the proton. This limit on the effective cross section is consistent with previous measurements as well as with Monte Carlo event generator predictions.
Expected and observed upper limits on the cross section for inclusive same-sign WW production via DPS
A search for new physics using events containing an imbalance in transverse momentum and one or more energetic jets arising from initial-state radiation or the hadronic decay of W or Z bosons is presented. A data sample of proton-proton collisions at $\sqrt{s} = $ 13 TeV, collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 35.9 fb$^{-1}$, is used. The observed data are found to be in agreement with the expectation from standard model processes. The results are interpreted as limits on the dark matter production cross section in simplified models with vector, axial-vector, scalar, and pseudoscalar mediators. Interpretations in the context of fermion portal and nonthermal dark matter models are also provided. In addition, the results are interpreted in terms of invisible decays of the Higgs boson and set stringent limits on the fundamental Planck scale in the Arkani-Hamed, Dimopoulos, and Dvali model with large extra spatial dimensions.
Comparison between data and MC simulation in the $\gamma$+jets control sample before and after performing the simultaneous fit across all the control samples and the signal region assuming the absence of any signal. The plot shows the monojet category. The hadronic recoil $p_{T}$ in $\gamma$+jets events is used as a proxy for $p_{T}^{miss}$ in the signal region. The last bin includes all events with hadronic recoil $p_{T}$ larger than 1250 GeV in the monojet category.
Comparison between data and MC simulation in the $\gamma$+jets control sample before and after performing the simultaneous fit across all the control samples and the signal region assuming the absence of any signal. The plot shows the mono-V category. The hadronic recoil $p_{T}$ in $\gamma$+jets events is used as a proxy for $p_{T}^{miss}$ in the signal region. The last bin includes all events with hadronic recoil $p_{T}$ larger than 750 GeV in the mono-V category.
Comparison between data and MC simulation in the dimuon control samples before and after performing the simultaneous fit across all the control samples and the signal region assuming the absence of any signal. Plot correspond to the monojet category. The hadronic recoil $p_{T}$ in dilepton events is used as a proxy for $p_{T}^{miss}$ in the signal region. The leading contribution is represented by Z+jets production. The other backgrounds include top quark, diboson, and W+jets processes.
Using a low background data sample of $9.7\times10^{5}$ $J\psi\rightarrow\gamma\eta^\prime$, $\eta^\prime\rightarrow\gamma\pi^+\pi^-$ events, which are 2 orders of magnitude larger than those from the previous experiments, recorded with the BESIII detector at BEPCII, the decay dynamics of $\eta^\prime\rightarrow\gamma\pi^+\pi^-$ are studied with both model-dependent and model-independent approaches. The contributions of $\omega$ and the $\rho(770)-\omega$ interference are observed for the first time in the decays $\eta^\prime\rightarrow\gamma\pi^+\pi^-$ in both approaches. Additionally, a contribution from the box anomaly or the $\rho(1450)$ resonance is required in the model-dependent approach, while the process specific part of the decay amplitude is determined in the model-independent approach.
Numbers of events selected (Column 2), numbers of background events from sideband (Column 3), efficiencies (Column 4), and resolution RMS (Column 5) for different $M_{\pi^+\pi^-}$ bins.
We present measurements of two-particle angular correlations between high-transverse-momentum ($2<p_T<11$ GeV/$c$) $\pi^0$ observed at midrapidity ($|\eta|<0.35$) and particles produced either at forward ($3.1<\eta<3.9$) or backward ($-3.7<\eta<-3.1$) rapidity in $d$$+$Au and $p$$+$$p$ collisions at $\sqrt{s_{_{NN}}}=200$ GeV. The azimuthal angle correlations for particle pairs with this large rapidity gap in the Au-going direction exhibit a ridge-like structure that persists up to $p_T{\approx}6$ GeV/$c$ and which strongly depends on collision centrality, which is a similar characteristic to the hydrodynamical particle flow in A+A collisions. The ridge-like structure is absent in the $d$-going direction as well as in $p$$+$$p$ collisions, in the transverse-momentum range studied. The results indicate that the ridge-like structure is shifted in the Au-going direction toward more central collisions, similar to the charged-particle pseudorapidity distributions.
Fourier fit coefficients for CNT-MPCS (Au-going) correlations, as a function of collision system and $\pi^0$ $p_T$: (a) the negative of the dipole coefficient, $-c_1$; (b) the quadrupole coefficient $c_2$; (c) the ratio ${-c_2}/{c_1}$.
Fourier fit coefficients for CNT-MPCS (Au-going) correlations, as a function of collision system and $\pi^0$ $p_T$: Fractional systematic uncertainty on the quadrupole coefficient $c_2$ for $d$+Au.
Fourier fit coefficients for CNT-MPCS (Au-going) correlations, as a function of collision system and $\pi^0$ $p_T$: Fractional systematic uncertainty on the quadrupole coefficient $c_2$ for $p$+$p$.
We report the measurement of the $\gamma p \rightarrow K^{+}\Lambda$ and $\gamma p \rightarrow K^{+}\Sigma^{0}$ reactions at SPring-8. The differential cross sections and photon-beam asymmetries are measured at forward $K^{+}$ production angles using linearly polarized tagged-photon beams in the range of $E_{\gamma}=1.5$--3.0 GeV. With increasing photon energy, the cross sections for both $\gamma p \rightarrow K^{+}\Lambda$ and $\gamma p \rightarrow K^{+}\Sigma^{0}$ reactions decrease slowly. Distinct narrow structures in the production cross section have not been found at $E_{\gamma}=1.5$--3.0 GeV. The forward peaking in the angular distributions of cross sections, a characteristic feature of $t$-channel exchange, is observed for the production of $\Lambda$ in the whole observed energy range. A lack of similar feature for $\Sigma^{0}$ production reflects a less dominant role of $t$-channel contribution in this channel. The photon-beam asymmetries remain positive for both reactions, suggesting the dominance of $K^{*}$ exchange in the $t$ channel. These asymmetries increase gradually with the photon energy, and have a maximum value of +0.6 for both reactions. Comparison with theoretical predictions based on the Regge trajectory in the $t$ channel and the contributions of nucleon resonances indicates the major role of $t$-channel contributions as well as non-negligible effects of nucleon resonances in accounting for the reaction mechanism of hyperon photoproduction in this photon energy regime.
Differential cross sections for the GAMMA P --> K+ LAMBDA reaction as a function of photon energy Egamma for the kaon c.m. production polar angle 0.6 < cos(theta) < 0.7.
Differential cross sections for the GAMMA P --> K+ LAMBDA reaction as a function of photon energy Egamma for the kaon c.m. production polar angle 0.7 < cos(theta) < 0.8.
Differential cross sections for the GAMMA P --> K+ LAMBDA reaction as a function of photon energy Egamma for the kaon c.m. production polar angle 0.8 < cos(theta) < 0.9.
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