An inclusive search for the standard model Higgs boson ($\mathrm{H}$) produced with large transverse momentum ($p_\mathrm{T}$) and decaying to a bottom quark-antiquark pair ($\mathrm{b}\overline{\mathrm{b}}$) is performed using a data set of pp collisions at $\sqrt{s}=$ 13 TeV collected with the CMS experiment at the LHC. The data sample corresponds to an integrated luminosity of 35.9 fb$^{-1}$. A highly Lorentz-boosted Higgs boson decaying to $\mathrm{b}\overline{\mathrm{b}}$ is reconstructed as a single, large radius jet and is identified using jet substructure and dedicated $\mathrm{b}$ tagging techniques. The method is validated with $\mathrm{Z}\to\mathrm{b}\overline{\mathrm{b}}$ decays. The $\mathrm{Z}\to\mathrm{b}\overline{\mathrm{b}}$ process is observed for the first time in the single-jet topology with a local significance of 5.1 standard deviations (5.8 expected). For a Higgs boson mass of 125 GeV, an excess of events above the expected background is observed (expected) with a local significance of 1.5 (0.7) standard deviations. The measured cross section times branching fraction for production via gluon fusion of $\mathrm{H} \rightarrow \mathrm{b}\overline{\mathrm{b}}$ with $p_\mathrm{T} > $450 GeV and in the pseudorapidity range $-$2.5 $< \eta <$ 2.5 is 74 $\pm$ 48 (stat) $_{-10}^{+17}$ (syst) fb, which is consistent within uncertainties with the standard model prediction.
A search is presented for additional neutral Higgs bosons in the $\tau\tau$ final state in proton-proton collisions at the LHC. The search is performed in the context of the minimal supersymmetric extension of the standard model (MSSM), using the data collected with the CMS detector in 2016 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. To enhance the sensitivity to neutral MSSM Higgs bosons, the search includes production of the Higgs boson in association with b quarks. No significant deviation above the expected background is observed. Model-independent limits at 95% confidence level (CL) are set on the product of the branching fraction for the decay into $\tau$ leptons and the cross section for the production via gluon fusion or in association with b quarks. These limits range from 18 pb at 90 GeV to 3.5 fb at 3.2 TeV for gluon fusion and from 15 pb (at 90 GeV) to 2.5 fb (at 3.2 TeV) for production in association with b quarks, assuming a narrow width resonance. In the m$_{\text{h}}^{\text{mod+}}$ scenario these limits translate into a 95% CL exclusion of $\tan\beta>$ 6 for neutral Higgs boson masses below 250 GeV, where $\tan\beta$ is the ratio of the vacuum expectation values of the neutral components of the two Higgs doublets. The 95% CL exclusion contour reaches 1.6 TeV for $\tan\beta=$ 60.
Searches for resonant and nonresonant pair-produced Higgs bosons (HH) decaying respectively into ll nu nu, through either W or Z bosons, and bbbar are presented. The analyses are based on a sample of proton-proton collisions at sqrt(s) = 13 TeV, collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 35.9 inverse femtobarns. Data and predictions from the standard model are in agreement within uncertainties. For the standard model HH hypothesis, the data exclude at 95% confidence level a product of the production cross section and branching fraction larger than 72 fb, corresponding to 79 times the prediction, consistent with expectations. Constraints are placed on different scenarios considering anomalous couplings, which could affect the rate and kinematics of HH production. Upper limits at 95% confidence level are set on the production cross section of narrow-width spin-0 and spin-2 particles decaying to Higgs boson pairs, the latter produced with minimal gravity-like coupling.
A search is presented for the decays of heavy exotic long-lived particles (LLPs) that are produced in proton-proton collisions at a center-of-mass energy of 13 TeV at the CERN LHC and come to rest in the CMS detector. Their decays would be visible during periods of time well separated from proton-proton collisions. Two decay scenarios of stopped LLPs are explored: a hadronic decay detected in the calorimeter and a decay into muons detected in the muon system. The calorimeter (muon) search covers a period of sensitivity totaling 721 (744) hours in 38.6 (39.0) fb$^{-1}$ of data collected by the CMS detector in 2015 and 2016. The results are interpreted in several scenarios that predict LLPs. Production cross section limits are set as a function of the mean proper lifetime and the mass of the LLPs, for lifetimes between 100 ns and 10 days. These are the most stringent limits to date on the mass of hadronically decaying stopped LLPs, and this is the first search at the LHC for stopped LLPs that decay to muons.
A measurement of the groomed jet mass in PbPb and pp collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV with the CMS detector at the LHC is presented. Jet grooming is a recursive procedure which sequentially removes soft constituents of a jet until a pair of hard subjets is found. The resulting groomed jets can be used to study modifications to the parton shower evolution in the presence of the hot and dense medium created in heavy ion collisions. Predictions of groomed jet properties from the PYTHIA and HERWIG++ event generators agree with the measurements in pp collisions. When comparing the results from the most central PbPb collisions to pp data, a hint of an increase of jets with large jet mass is observed, which could originate from additional medium-induced radiation at a large angle from the jet axis. However, no modification of the groomed mass of the core of the jet is observed for all PbPb centrality classes. The PbPb results are also compared to predictions from the JEWEL and Q-PYTHIA event generators, which predict a large modification of the groomed mass not observed in the data.
A search for the production of Higgs boson pairs in proton-proton collisions at a centre-of-mass energy of 13 TeV is presented, using a data sample corresponding to an integrated luminosity of 35.9 inverse femtobarns collected with the CMS detector at the LHC. Events with one Higgs boson decaying into two bottom quarks and the other decaying into two tau leptons are explored to investigate both resonant and nonresonant production mechanisms. The data are found to be consistent, within uncertainties, with the standard model background predictions. For resonant production, upper limits at the 95% confidence level are set on the production cross section for Higgs boson pairs as a function of the hypothesized resonance mass and are interpreted in the context of the minimal supersymmetric standard model. For nonresonant production, upper limits on the production cross section constrain the parameter space for anomalous Higgs boson couplings. The observed (expected) upper limit at 95% confidence level corresponds to about 30 (25) times the prediction of the standard model.
An analysis of the decay $\Lambda_b \to J/\psi(\to\mu^+\mu^-)\Lambda(\to p \pi^-)$ decay is performed to measure the $\Lambda_b$ polarization and three angular parameters in data from pp collisions at $\sqrt{s} =$ 7 and 8 TeV, collected by the CMS experiment at the LHC. The $\Lambda_b$ polarization is measured to be 0.00 $\pm$ 0.06 (stat) $\pm$ 0.06 (syst) and the parity-violating asymmetry parameter is determined to be 0.14 $\pm$ 0.14 (stat) $\pm$ 0.10 (syst). The measurements are compared to various theoretical predictions, including those from perturbative quantum chromodynamics.
A search is presented for the associated production of a Higgs boson with a top quark pair in the all-jet final state. Events containing seven or more jets are selected from a sample of proton-proton collisions at $\sqrt{s} =$ 13 TeV collected with the CMS detector at the LHC in 2016, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. To separate the $\mathrm{t}\overline{\mathrm{t}}$H signal from the irreducible $\mathrm{t}\overline{\mathrm{t}}+\mathrm{b}\overline{\mathrm{b}}$ background, the analysis assigns leading order matrix element signal and background probability densities to each event. A likelihood-ratio statistic based on these probability densities is used to extract the signal. The results are provided in terms of an observed $\mathrm{t}\overline{\mathrm{t}}$H signal strength relative to the standard model production cross section $\mu=\sigma/\sigma_\mathrm{SM}$, assuming a Higgs boson mass of 125 GeV. The best fit value is $\hat{\mu} =$ 0.9 $\pm$ 0.7 (stat) $\pm$ 1.3 (syst) = 0.9 $\pm$ 1.5 (tot), and the observed and expected upper limits are, respectively, $\mu <$ 3.8 and $<$ 3.1 at 95% confidence levels.
Measurements of differential cross sections d$\sigma$/d$\phi^*$ and double-differential cross sections d$^2\sigma$/d$\phi^*\,$d$|y|$ for inclusive Z boson production are presented using the dielectron and dimuon final states. The kinematic observable $\phi^*$ correlates with the dilepton transverse momentum but has better resolution, and $y$ is the dilepton rapidity. The analysis is based on data collected with the CMS experiment at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7 fb$^{-1}$. The normalised cross section (1/$\sigma$)$\,$d$\sigma$/d$\phi^*$, within the fiducial kinematic region, is measured with a precision of better than 0.5% for $\phi^*$ < 1. The measurements are compared to theoretical predictions and they agree, typically, within few percent.
A measurement is presented of the triple-differential dijet cross section at a centre-of-mass energy of 8 TeV using 19.7 inverse femtobarns of data collected with the CMS detector in proton-proton collisions at the LHC. The cross section is measured as a function of the average transverse momentum, half the rapidity separation, and the boost of the two leading jets in the event. The cross section is corrected for detector effects and compared to calculations in perturbative quantum chromodynamics at next-to-leading order accuracy, complemented with electroweak and nonperturbative corrections. New constraints on parton distribution functions are obtained and the inferred value of the strong coupling constant is alpha[S](M[Z]) = 0.1199 +/- 0.0015 (exp) -0.0020 +0.0031 (theo), where M[Z] is the mass of the Z boson.
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