Search

The original article can be found online at https://doi.org/10.1140/epjc/s10052-018-6242-x. J. C (2018) 78:789 https://doi.org/10.1140/epjc/s10052-018-6242-x In this article the author name Luigi Calligaris was incorrectly written as A. Calligaris. [Extracted from the article]

The original article can be found online at https://doi.org/10.1140/epjc/s10052-018-6332-9. J. C (2018) 78:891 https://doi.org/10.1140/epjc/s10052-018-6332-9 In this article the author name Luigi Calligaris was incorrectly written as A. Calligaris. [Extracted from the article]

The original article can be found online at https://doi.org/10.1140/epjc/s10052-019-6774-8. Erratum to: Measurement of exclusive photoproduction from protons in pPb collisions at sNN=5.02TeV J. C (2019) 79:277 https://doi.org/10.1140/epjc/s10052-019-6774-8 In this article the author name Luigi Calligaris was incorrectly written as A. Calligaris. [Extracted from the article]

A Correction to this paper has been published: https://doi.org/10.1140/epjc/s10052-020-08562-y [ABSTRACT FROM AUTHOR]

Measurements are presented of the single-diffractive dijet cross section and the diffractive cross section as a function of the proton fractional momentum loss ξ and the four-momentum transfer squared t. Both processes p p → p X and p p → X p , i.e. with the proton scattering to either side of the interaction point, are measured, where X includes at least two jets; the results of the two processes are averaged. The analyses are based on data collected simultaneously with the CMS and TOTEM detectors at the LHC in proton–proton collisions at s = 8 Te during a dedicated run with β ∗ = 90 m at low instantaneous luminosity and correspond to an integrated luminosity of 37.5 nb - 1 . The single-diffractive dijet cross section σ jj p X , in the kinematic region ξ < 0.1 , 0.03 < | t | < 1 Ge 2 , with at least two jets with transverse momentum p T > 40 Ge , and pseudorapidity | η | < 4.4 , is 21.7 ± 0.9 (stat) - 3.3 + 3.0 (syst) ± 0.9 (lumi) nb . The ratio of the single-diffractive to inclusive dijet yields, normalised per unit of ξ , is presented as a function of x, the longitudinal momentum fraction of the proton carried by the struck parton. The ratio in the kinematic region defined above, for x values in the range - 2.9 ≤ log 10 x ≤ - 1.6 , is R = (σ jj p X / Δ ξ) / σ jj = 0.025 ± 0.001 (stat) ± 0.003 (syst) , where σ jj p X and σ jj are the single-diffractive and inclusive dijet cross sections, respectively. The results are compared with predictions from models of diffractive and nondiffractive interactions. Monte Carlo predictions based on the HERA diffractive parton distribution functions agree well with the data when corrected for the effect of soft rescattering between the spectator partons. [ABSTRACT FROM AUTHOR]

Normalised multi-differential cross sections for top quark pair ( t t ¯ ) production are measured in proton-proton collisions at a centre-of-mass energy of 13 TeV using events containing two oppositely charged leptons. The analysed data were recorded with the CMS detector in 2016 and correspond to an integrated luminosity of 35.9 fb - 1 . The double-differential t t ¯ cross section is measured as a function of the kinematic properties of the top quark and of the t t ¯ system at parton level in the full phase space. A triple-differential measurement is performed as a function of the invariant mass and rapidity of the t t ¯ system and the multiplicity of additional jets at particle level. The data are compared to predictions of Monte Carlo event generators that complement next-to-leading-order (NLO) quantum chromodynamics (QCD) calculations with parton showers. Together with a fixed-order NLO QCD calculation, the triple-differential measurement is used to extract values of the strong coupling strength α S and the top quark pole mass ( m t pole ) using several sets of parton distribution functions (PDFs). The measurement of m t pole exploits the sensitivity of the t t ¯ invariant mass distribution to m t pole near the production threshold. Furthermore, a simultaneous fit of the PDFs, α S , and m t pole is performed at NLO, demonstrating that the new data have significant impact on the gluon PDF, and at the same time allow an accurate determination of α S and m t pole . The values α S (m Z) = 0.1135 - 0.0017 + 0.0021 and m t pole = 170.5 ± 0.8 GeV are extracted, which account for experimental and theoretical uncertainties, the latter being estimated from NLO scale variations. Possible effects from Coulomb and soft-gluon resummation near the t t ¯ production threshold are neglected in these parameter extractions. A rough estimate of these effects indicates an expected correction of m t pole of the order of + 1 GeV , which can be regarded as additional theoretical uncertainty in the current m t pole extraction. [ABSTRACT FROM AUTHOR]

Events with no charged particles produced between the two leading jets are studied in proton-proton collisions at [ABSTRACT FROM AUTHOR]

A measurement is presented of electroweak (EW) production of a W boson in association with two jets in proton–proton collisions at s = 13 Te . The data sample was recorded by the CMS Collaboration at the LHC and corresponds to an integrated luminosity of 35.9 fb - 1 . The measurement is performed for the ℓ ν jj final state (with ℓ ν indicating a lepton–neutrino pair, and j representing the quarks produced in the hard interaction) in a kinematic region defined by invariant mass m jj > 120 Ge and transverse momenta p T j > 25 Ge . The cross section of the process is measured in the electron and muon channels yielding σ EW (W jj) = 6.23 ± 0.12 (stat) ± 0.61 (syst) pb per channel, in agreement with leading-order standard model predictions. The additional hadronic activity of events in a signal-enriched region is studied, and the measurements are compared with predictions. The final state is also used to perform a search for anomalous trilinear gauge couplings. Limits on anomalous trilinear gauge couplings associated with dimension-six operators are given in the framework of an effective field theory. The corresponding 95% confidence level intervals are - 2.3 < c W W W / Λ 2 < 2.5 Te - 2 , - 8.8 < c W / Λ 2 < 16 Te - 2 , and - 45 < c B / Λ 2 < 46 Te - 2 . These results are combined with the CMS EW Zjj analysis, yielding the constraint on the c W W W coupling: - 1.8 < c W W W / Λ 2 < 2.0 Te - 2 . [ABSTRACT FROM AUTHOR]

New sets of CMS underlying-event parameters ("tunes") are presented for the pythia8 event generator. These tunes use the NNPDF3.1 parton distribution functions (PDFs) at leading (LO), next-to-leading (NLO), or next-to-next-to-leading (NNLO) orders in perturbative quantum chromodynamics, and the strong coupling evolution at LO or NLO. Measurements of charged-particle multiplicity and transverse momentum densities at various hadron collision energies are fit simultaneously to determine the parameters of the tunes. Comparisons of the predictions of the new tunes are provided for observables sensitive to the event shapes at LEP, global underlying event, soft multiparton interactions, and double-parton scattering contributions. In addition, comparisons are made for observables measured in various specific processes, such as multijet, Drell–Yan, and top quark-antiquark pair production including jet substructure observables. The simulation of the underlying event provided by the new tunes is interfaced to a higher-order matrix-element calculation. For the first time, predictions from pythia8 obtained with tunes based on NLO or NNLO PDFs are shown to reliably describe minimum-bias and underlying-event data with a similar level of agreement to predictions from tunes using LO PDF sets. [ABSTRACT FROM AUTHOR]

Measurements are presented of the triple-differential cross section for inclusive isolated-photon+jet events in p p collisions at s = 8 TeV as a function of photon transverse momentum ( p T γ ), photon pseudorapidity ( η γ ), and jet pseudorapidity ( η jet ). The data correspond to an integrated luminosity of 19.7 fb - 1 that probe a broad range of the available phase space, for | η γ | < 1.44 and 1.57 < | η γ | < 2.50 , | η jet | < 2.5 , 40 < p T γ < 1000 GeV , and jet transverse momentum, p T jet , > 25 GeV . The measurements are compared to next-to-leading order perturbative quantum chromodynamics calculations, which reproduce the data within uncertainties. [ABSTRACT FROM AUTHOR]

A search for new physics in top quark production is performed in proton-proton collisions at 13 TeV . The data set corresponds to an integrated luminosity of 35.9 fb - 1 collected in 2016 with the CMS detector. Events with two opposite-sign isolated leptons (electrons or muons), and b quark jets in the final state are selected. The search is sensitive to new physics in top quark pair production and in single top quark production in association with a W boson. No significant deviation from the standard model expectation is observed. Results are interpreted in the framework of effective field theory and constraints on the relevant effective couplings are set, one at a time, using a dedicated multivariate analysis. This analysis differs from previous searches for new physics in the top quark sector by explicitly separating t W from t t ¯ events and exploiting the specific sensitivity of the t W process to new physics. [ABSTRACT FROM AUTHOR]

Measurements of the associated production of a $$\mathrm{Z}$$ boson with at least one jet originating from a b quark in proton-proton collisions at $$\sqrt{s} = 8\,\text {TeV} $$ are presented. Differential cross sections are measured with data collected by the CMS experiment corresponding to an integrated luminosity of 19.8 $$\,\text {fb}^{-1}$$ . $$\mathrm{Z}$$ bosons are reconstructed through their decays to electrons and muons. Cross sections are measured as a function of observables characterizing the kinematics of the $$\mathrm{b}$$ jet and the $$\mathrm{Z}$$ boson. Ratios of differential cross sections for the associated production with at least one $$\mathrm{b}$$ jet to the associated production with any jet are also presented. The production of a $$\mathrm{Z}$$ boson with at least two $$\mathrm{b}$$ jets is investigated, and differential cross sections are measured for the dijet system. Results are compared to theoretical predictions, testing two different flavour schemes for the choice of initial-state partons. [ABSTRACT FROM AUTHOR]

A measurement is presented of the triple-differential dijet cross section at a centre-of-mass energy of 8 $$\,\text {TeV}$$ using 19.7 $$\,\text {fb}^\text {-1}$$ 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 $$\alpha _S(M_\text {Z}) = 0.1199\,\pm {0.0015}\,(\mathrm {exp})\, _{-0.0020}^{+0.0031}\,(\mathrm {theo})$$ , where $$M_\text {Z}$$ is the mass of the Z boson. [ABSTRACT FROM AUTHOR]

A search for new phenomena is performed using events with jets and significant transverse momentum imbalance, as inferred through the $$M_{\mathrm {T2}}$$ variable. The results are based on a sample of proton-proton collisions collected in 2016 at a center-of-mass energy of 13 $$\,\text {TeV}$$ with the CMS detector and corresponding to an integrated luminosity of 35.9 $$\,\text {fb}^\text {-1}$$ . No excess event yield is observed above the predicted standard model background, and the results are interpreted as exclusion limits at 95% confidence level on the masses of predicted particles in a variety of simplified models of R-parity conserving supersymmetry. Depending on the details of the model, 95% confidence level lower limits on the gluino (light-flavor squark) masses are placed up to 2025 (1550) $$\,\text {GeV}$$ . Mass limits as high as 1070 (1175) $$\,\text {GeV}$$ are set on the masses of top (bottom) squarks. Information is provided to enable re-interpretation of these results, including model-independent limits on the number of non-standard model events for a set of simplified, inclusive search regions. [ABSTRACT FROM AUTHOR]

A search for heavy resonances with masses above 1 TeV, decaying to final states containing a vector boson and a Higgs boson, is presented. The search considers hadronic decays of the vector boson, and Higgs boson decays to b quarks. The decay products are highly boosted, and each collimated pair of quarks is reconstructed as a single, massive jet. The analysis is performed using a data sample collected in 2016 by the CMS experiment at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb-1. The data are consistent with the background expectation and are used to place limits on the parameters of a theoretical model with a heavy vector triplet. In the benchmark scenario with mass-degenerate W′ and Z′ bosons decaying predominantly to pairs of standard model bosons, for the first time heavy resonances for masses as high as 3.3 TeV are excluded at 95% confidence level, setting the most stringent constraints to date on such states decaying into a vector boson and a Higgs boson. [ABSTRACT FROM AUTHOR]

Results are reported from a search for physics beyond the standard model in final states with at least three charged leptons, in any combination of electrons or muons. The data sample corresponds to an integrated luminosity of 2.3 fb−1 of proton–proton collisions at √s = 13 TeV, recorded by the CMS experiment at the LHC in 2015. Two jets are required in each event, providing good sensitivity to strong production of gluinos and squarks. The search regions, sensitive to a range of different new physics scenarios, are defined using the number of jets tagged as originating from bottom quarks, the sum of the magnitudes of the transverse momenta of the jets, the imbalance in the overall transverse momentum in the event, and the invariant mass of oppositesign, same-flavor lepton pairs. The event yields observed in data are consistent with the expected background contributions from standard model processes. These results are used to derive limits in terms of R-parity conserving simplified models of supersymmetry that describe strong production of gluinos and squarks.Model-independent limits are presented to facilitate the reinterpretation of the results in a broad range of scenarios for physics beyond the standard model. [ABSTRACT FROM AUTHOR]

A data sample of events from proton-proton collisions with two isolated same-sign leptons, missing transverse momentum, and jets is studied in a search for signatures of new physics phenomena by the CMS Collaboration at the LHC. The data correspond to an integrated luminosity of 35.9 fb-1, and a center-of-mass energy of 13 TeV. The properties of the events are consistent with expectations from standard model processes, and no excess yield is observed. Exclusion limits at 95% confidence level are set on cross sections for the pair production of gluinos, squarks, and same-sign top quarks, as well as top-quark associated production of a heavy scalar or pseudoscalar boson decaying to top quarks, and on the standard model production of events with four top quarks. The observed lower mass limits are as high as 1500 GeV for gluinos, 830 GeV for bottom squarks. The excluded mass range for heavy (pseudo)scalar bosons is 350-360 (350-410) GeV. Additionally, model-independent limits in several topological regions are provided, allowing for further interpretations of the results. [ABSTRACT FROM AUTHOR]

The first measurement of the jet mass $$m_{\text {jet}}$$ of top quark jets produced in $${\mathrm{t}}\overline{\mathrm{t}} $$ events from pp collisions at $$\sqrt{s}=8$$ $$\,\text {TeV}$$ is reported for the jet with the largest transverse momentum $$p_{\mathrm{T}}$$ in highly boosted hadronic top quark decays. The data sample, collected with the CMS detector, corresponds to an integrated luminosity of 19.7 $$\,\text {fb}^{-1}$$ . The measurement is performed in the lepton+jets channel in which the products of the semileptonic decay $${\mathrm{t}} \rightarrow \mathrm{b} \mathrm {W}$$ with $$\mathrm {W}\rightarrow \ell \nu $$ where $$\ell $$ is an electron or muon, are used to select $${\mathrm{t}}\overline{\mathrm{t}} $$ events with large Lorentz boosts. The products of the fully hadronic decay $${\mathrm{t}} \rightarrow \mathrm{b} \mathrm {W}$$ with $$\mathrm {W}\rightarrow \mathrm{q} \overline{\mathrm{q}} '$$ are reconstructed using a single Cambridge-Aachen jet with distance parameter $$R=1.2$$ , and $$p_{\mathrm{T}} >400$$ $$\,\text {GeV}$$ . The $${\mathrm{t}}\overline{\mathrm{t}} $$ cross section as a function of $$m_{\text {jet}}$$ is unfolded at the particle level and is used to test the modelling of highly boosted top quark production. The peak position of the $$m_{\text {jet}}$$ distribution is sensitive to the top quark mass $$m_{{\mathrm{t}}}$$ , and the data are used to extract a value of $$m_{{\mathrm{t}}}$$ to assess this sensitivity. [ABSTRACT FROM AUTHOR]

A measurement of the top quark mass is reported in events containing a single top quark produced via the electroweak t channel. The analysis is performed using data from proton-proton collisions collected with the CMS detector at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb $$^{-1}$$ . Top quark candidates are reconstructed from their decay to a $$\mathrm {W}$$ boson and a b quark, with the $$\mathrm {W}$$ boson decaying leptonically to a muon and a neutrino. The final state signature and kinematic properties of single top quark events in the t channel are used to enhance the purity of the sample, suppressing the contribution from top quark pair production. A fit to the invariant mass distribution of reconstructed top quark candidates yields a value of the top quark mass of $$172.95 \pm 0.77\,\text {(stat)} ^{+0.97}_{-0.93}\,\text {(syst)} \,\text {GeV} $$ . This result is in agreement with the current world average, and represents the first measurement of the top quark mass in event topologies not dominated by top quark pair production, therefore contributing to future averages with partially uncorrelated systematic uncertainties and a largely uncorrelated statistical uncertainty. [ABSTRACT FROM AUTHOR]

Searches are presented for direct production of top or bottom squark pairs in proton-proton collisions at the CERN LHC. Two searches, based on complementary techniques, are performed in all-jet final states that are characterized by a significant imbalance in transverse momentum. An additional search requires the presence of a charged lepton isolated from other activity in the event. The data were collected in 2015 at a centre-of-mass energy of 13 $$\,\text {TeV}$$ with the CMS detector and correspond to an integrated luminosity of 2.3 $$\,\text {fb}^{-1}$$ . No statistically significant excess of events is found beyond the expected contribution from standard model processes. Exclusion limits are set in the context of simplified models of top or bottom squark pair production. Models with top and bottom squark masses up to 830 and 890 $$\,\text {GeV}$$ , respectively, are probed for light neutralinos. For models with top squark masses of 675 $$\,\text {GeV}$$ , neutralino masses up to 260 $$\,\text {GeV}$$ are excluded at 95% confidence level. [ABSTRACT FROM AUTHOR]

A search for new phenomena is performed in final states containing one or more jets and an imbalance in transverse momentum in pp collisions at a centre-of-mass energy of 13 $$\,\text {TeV}$$ . The analysed data sample, recorded with the CMS detector at the CERN LHC, corresponds to an integrated luminosity of 2.3 $$\,\text {fb}^{-1}$$ . Several kinematic variables are employed to suppress the dominant background, multijet production, as well as to discriminate between other standard model and new physics processes. The search provides sensitivity to a broad range of new-physics models that yield a stable weakly interacting massive particle. The number of observed candidate events is found to agree with the expected contributions from standard model processes, and the result is interpreted in the mass parameter space of fourteen simplified supersymmetric models that assume the pair production of gluinos or squarks and a range of decay modes. For models that assume gluino pair production, masses up to 1575 and 975 $$\,\text {GeV}$$ are excluded for gluinos and neutralinos, respectively. For models involving the pair production of top squarks and compressed mass spectra, top squark masses up to 400 $$\,\text {GeV}$$ are excluded. [ABSTRACT FROM AUTHOR]

A search for narrow resonances decaying to an electron and a muon is presented. The $$\mathrm {e}$$ $${\mu }$$ mass spectrum is also investigated for non-resonant contributions from the production of quantum black holes (QBHs). The analysis is performed using data corresponding to an integrated luminosity of 19.7 $$~\text {fb}^\text {-1}$$ collected in proton-proton collisions at a centre-of-mass energy of 8 $$~\text {TeV}$$ with the CMS detector at the LHC. With no evidence for physics beyond the standard model in the invariant mass spectrum of selected $$\mathrm {e}\mu $$ pairs, upper limits are set at 95 $$\%$$ confidence level on the product of cross section and branching fraction for signals arising in theories with charged lepton flavour violation. In the search for narrow resonances, the resonant production of a $$\mathrm {\tau }$$ sneutrino in R-parity violating supersymmetry is considered. The $$\mathrm {\tau }$$ sneutrino is excluded for masses below 1.28 $$~\text {TeV}$$ for couplings $$\lambda _{132}=\lambda _{231}=\lambda '_{311}=0.01$$ , and below 2.30 $$~\text {TeV}$$ for $$\lambda _{132}=\lambda _{231}=0.07$$ and $$\lambda '_{311}=0.11$$ . These are the most stringent limits to date from direct searches at high-energy colliders. In addition, the resonance searches are interpreted in terms of a model with heavy partners of the $${\mathrm {Z}} $$ boson and the photon. In a framework of TeV-scale quantum gravity based on a renormalization of Newton's constant, the search for non-resonant contributions to the $$\mathrm {e}$$ $${\mu }$$ mass spectrum excludes QBH production below a threshold mass $$M_{\mathrm {th}}$$ of 1.99 $$~\text {TeV}$$ . In models that invoke extra dimensions, the bounds range from 2.36 $$~\text {TeV}$$ for one extra dimension to 3.63 $$~\text {TeV}$$ for six extra dimensions. This is the first search for QBHs decaying into the $$\mathrm {e}$$ $${\mu }$$ final state. [ABSTRACT FROM AUTHOR]

A measurement of the forward-backward asymmetry $${A}_{\mathrm{FB}}$$ of oppositely charged lepton pairs ( $$\mu \mu $$ and $$\mathrm{e}\mathrm{e}$$ ) produced via $$\mathrm{Z}/\gamma ^*$$ boson exchange in pp collisions at $$\sqrt{s} = 8$$ $$\,\mathrm{TeV}$$ is presented. The data sample corresponds to an integrated luminosity of 19.7 $$\,\mathrm{fb}^{-1}$$ collected with the CMS detector at the LHC. The measurement of $${A}_{\mathrm{FB}}$$ is performed for dilepton masses between 40 $$\,\text {GeV}$$ and 2 $$\,\mathrm{TeV}$$ and for dilepton rapidity up to 5. The $${A}_{\mathrm{FB}}$$ measurements as a function of dilepton mass and rapidity are compared with the standard model predictions. [ABSTRACT FROM AUTHOR]

This paper presents a measurement of the inclusive 3-jet production differential cross section at a proton-proton centre-of-mass energy of 7 TeV using data corresponding to an integrated luminosity of 5 $$\,\mathrm{fb}^{-1}$$ collected with the CMS detector. The analysis is based on the three jets with the highest transverse momenta. The cross section is measured as a function of the invariant mass of the three jets in a range of 445-3270 GeV and in two bins of the maximum rapidity of the jets up to a value of 2. A comparison between the measurement and the prediction from perturbative QCD at next-to-leading order is performed. Within uncertainties, data and theory are in agreement. The sensitivity of the observable to the strong coupling constant $$\alpha _\mathrm {S}$$ is studied. A fit to all data points with 3-jet masses larger than 664 GeV gives a value of the strong coupling constant of $$\alpha _S(M_\mathrm{Z}) = 0.1171 \pm 0.0013\,\text {(exp)} \,^{+0.0073}_{-0.0047}\,\text {(theo)} $$ . [ABSTRACT FROM AUTHOR]

Measurements of the differential and double-differential Drell-Yan cross sections in the dielectron and dimuon channels are presented. They are based on proton-proton collision data at $$\sqrt{s} = 8\,\text {TeV} $$ recorded with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7 $$\,\text {fb}^{-1}$$ . The measured inclusive cross section in the $$\mathrm{Z}$$ peak region (60-120 $$\,\text {GeV}$$ ), obtained from the combination of the dielectron and dimuon channels, is $$1138 \pm 8\,\text {(exp)} \pm 25\,\text {(theo)} \pm 30\,\text {(lumi)} \text {\,pb} $$ , where the statistical uncertainty is negligible. The differential cross section $$\mathrm{d}\sigma /\mathrm{d}{}m$$ in the dilepton mass range 15-2000 $$\,\text {GeV}$$ is measured and corrected to the full phase space. The double-differential cross section $$\mathrm{d}^2\sigma /\mathrm{d}{}m\,\mathrm{d}|y |$$ is also measured over the mass range 20 to 1500 $$\,\text {GeV}$$ and absolute dilepton rapidity from 0 to 2.4. In addition, the ratios of the normalized differential cross sections measured at $$\sqrt{s} = 7$$ and 8 $$\,\text {TeV}$$ are presented. These measurements are compared to the predictions of perturbative QCD at next-to-leading and next-to-next-to-leading (NNLO) orders using various sets of parton distribution functions (PDFs). The results agree with the NNLO theoretical predictions computed with fewz 3.1 using the CT10 NNLO and NNPDF2.1 NNLO PDFs. The measured double-differential cross section and ratio of normalized differential cross sections are sufficiently precise to constrain the proton PDFs. [ABSTRACT FROM AUTHOR]

A study of dijet production in proton–proton collisions was performed at for jets with pT>35 GeV and |y|<4.7 using data collected with the CMS detector at the LHC in 2010. Events with at least one pair of jets are denoted as “inclusive”. Events with exactly one pair of jets are called “exclusive”. The ratio of the cross section of all pairwise combinations of jets to the exclusive dijet cross section as a function of the rapidity difference between jets |Δy| is measured for the first time up to |Δy|=9.2. The ratio of the cross section for the pair consisting of the most forward and the most backward jet from the inclusive sample to the exclusive dijet cross section is also presented. The predictions of the Monte Carlo event generators pythia6 and pythia8 agree with the measurements. In both ratios the herwig++ generator exhibits a more pronounced rise versus |Δy| than observed in the data. The BFKL-motivated generators cascade and hej+ariadne predict for these ratios a significantly stronger rise than observed. [ABSTRACT FROM AUTHOR]

A search for a doubly-charged Higgs boson in pp collisions at is presented. The data correspond to an integrated luminosity of 4.9 fb−1, collected by the CMS experiment at the LHC. The search is performed using events with three or more isolated charged leptons of any flavor, giving sensitivity to the decays of pair-produced triplet components Φ++Φ−−, and Φ++Φ− from associated production. No excess is observed compared to the background prediction, and upper limits at the 95 % confidence level are set on the Φ++ production cross section, under specific assumptions on its branching fractions. Lower bounds on the Φ++ mass are reported, providing significantly more stringent constraints than previously published limits. [ABSTRACT FROM AUTHOR]

Spectra of identified charged hadrons are measured in pp collisions at the LHC for $\sqrt{s} = 0.9, 2.76,\mbox{ and } 7~\mbox{TeV}$. Charged pions, kaons, and protons in the transverse-momentum range p≈0.1-1.7 GeV/ c and for rapidities | y|<1 are identified via their energy loss in the CMS silicon tracker. The average p increases rapidly with the mass of the hadron and the event charged-particle multiplicity, independently of the center-of-mass energy. The fully corrected p spectra and integrated yields are compared to various tunes of the Pythia 6 and Pythia 8 event generators. [ABSTRACT FROM AUTHOR]

The top-quark mass is measured in proton-proton collisions at $\sqrt{s} = 7\ \mbox{TeV}$ using a data sample corresponding to an integrated luminosity of 5.0 fb collected by the CMS experiment at the LHC. The measurement is performed in the dilepton decay channel $\mathrm{t}\overline{\mathrm{t}}\rightarrow(\ell^{+}\nu_{\ell}\mathrm{b})\,(\ell^{-}\overline{\nu}_{\ell}\overline{\mathrm{b}})$, where ℓ=e, μ. Candidate top-quark decays are selected by requiring two leptons, at least two jets, and imbalance in transverse momentum. The mass is reconstructed with an analytical matrix weighting technique using distributions derived from simulated samples. Using a maximum-likelihood fit, the top-quark mass is determined to be 172.5±0.4 (stat.)±1.5 (syst.) GeV. [ABSTRACT FROM AUTHOR]

Measurements from the CMS experiment at the LHC of dihadron correlations for charged particles produced in PbPb collisions at a nucleon-nucleon centre-of-mass energy of 2.76 TeV are presented. The results are reported as a function of the particle transverse momenta (pT) and collision centrality over a broad range in relative pseudorapidity (Δη) and the full range of relative azimuthal angle (Δɸ). The observed two-dimensional correlation structure in Δη and Δɸ is characterised by a narrow peak at (Δη, Δɸ)~ (0, 0) from jet-like correlations and a longrange structure that persists up to at least ∣Δη∣ = 4. An enhancement of the magnitude of the short-range jet peak is observed with increasing centrality, especially for particles of pT around 1-2 GeV/c. The long-range azimuthal dihadron correlations are extensively studied using a Fourier decomposition analysis. The extracted Fourier coefficients are found to factorise into a product of single-particle azimuthal anisotropies up to pT ~ 3-3.5 GeV/c for at least one particle from each pair, except for the second-order harmonics in the most central PbPb events. Various orders of the single-particle azimuthal anisotropy harmonics are extracted for associated particle pT of 1-3 GeV/c, as a function of the trigger particle pT up to 20 GeV/c and over the full centrality range. [ABSTRACT FROM AUTHOR]

A study of forward energy flow and central charged-particle multiplicity in events with W and Z bosons decaying into leptons is presented. The analysis uses a sample of 7 TeV pp collisions, corresponding to an integrated luminosity of 36 pb, recorded by the CMS experiment at the LHC. The observed forward energy depositions, their correlations, and the central charged-particle multiplicities are not well described by the available non-diffractive soft-hadron production models. A study of about 300 events with no significant energy deposited in one of the forward calorimeters, corresponding to a pseudorapidity gap of at least 1.9 units, is also presented. An indication for a diffractive component in these events comes from the observation that the majority of the charged leptons from the W(Z) decays are found in the hemisphere opposite to the gap. When fitting the signed lepton pseudorapidity distribution of these events with predicted distributions from an admixture of diffractive ( pompyt) and non-diffractive ( pythia) Monte Carlo simulations, the diffractive component is determined to be (50.0 ± 9.3 (stat.) ± 5.2 (syst.))%. [ABSTRACT FROM AUTHOR]

A measurement for inclusive 2- and 3-jet events of the azimuthal correlation between the two jets with the largest transverse momenta, Δ ϕ 12 , is presented. The measurement considers events where the two leading jets are nearly collinear ("back-to-back") in the transverse plane and is performed for several ranges of the leading jet transverse momentum. Proton-proton collision data collected with the CMS experiment at a center-of-mass energy of 13 Te and corresponding to an integrated luminosity of 35.9 fb - 1 are used. Predictions based on calculations using matrix elements at leading-order and next-to-leading-order accuracy in perturbative quantum chromodynamics supplemented with leading-log parton showers and hadronization are generally in agreement with the measurements. Discrepancies between the measurement and theoretical predictions are as large as 15%, mainly in the region 177 ∘ < Δ ϕ 12 < 180 ∘ . The 2- and 3-jet measurements are not simultaneously described by any of models. [ABSTRACT FROM AUTHOR]

Exclusive ρ 770 0 photoproduction is measured for the first time in ultraperipheral pPb collisions at s NN = 5.02 Te with the CMS detector. The cross section σ (γ p → ρ 770 0 p) is 11.0 ± 1.4 (stat) ± 1.0 (syst) μ b at ⟨ W γ p ⟩ = 92.6 Ge for photon–proton centre-of-mass energies W γ p between 29 and 213 Ge . The differential cross section d σ / d | t | is measured in the interval 0.025 < | t | < 1 Ge 2 as a function of W γ p , where t is the squared four-momentum transfer at the proton vertex. The results are compared with previous measurements and theoretical predictions. The measured cross section σ (γ p → ρ 770 0 p) has a power-law dependence on the photon–proton centre-of-mass, consistent with electron–proton collision measurements performed at HERA. The W γ p dependence of the exponential slope of the differential cross section d σ / d | t | is also measured. [ABSTRACT FROM AUTHOR]

A search is presented for a heavy pseudoscalar boson A decaying to a Z boson and a Higgs boson with mass of 125 GeV . In the final state considered, the Higgs boson decays to a bottom quark and antiquark, and the Z boson decays either into a pair of electrons, muons, or neutrinos. The analysis is performed using a data sample corresponding to an integrated luminosity of 35.9 fb - 1 collected in 2016 by the CMS experiment at the LHC from proton–proton collisions at a center-of-mass energy of 13 Te . The data are found to be consistent with the background expectations. Exclusion limits are set in the context of two-Higgs-doublet models in the A boson mass range between 225 and 1000 GeV . [ABSTRACT FROM AUTHOR]

A measurement of the top quark–antiquark pair production cross section σ t t ¯ in proton–proton collisions at a centre-of-mass energy of 13 Te is presented. The data correspond to an integrated luminosity of 35.9 fb - 1 , recorded by the CMS experiment at the CERN LHC in 2016. Dilepton events (e ± μ ∓ μ + μ - e + e - ) are selected and the cross section is measured from a likelihood fit. For a top quark mass parameter in the simulation of m t MC = 172.5 Ge the fit yields a measured cross section σ t t ¯ = 803 ± 2 (stat) ± 25 (syst) ± 20 (lumi) pb , in agreement with the expectation from the standard model calculation at next-to-next-to-leading order. A simultaneous fit of the cross section and the top quark mass parameter in the powheg simulation is performed. The measured value of m t MC = 172.33 ± 0.14 (stat) - 0.72 + 0.66 (syst) Ge is in good agreement with previous measurements. The resulting cross section is used, together with the theoretical prediction, to determine the top quark mass and to extract a value of the strong coupling constant with different sets of parton distribution functions. [ABSTRACT FROM AUTHOR]

A search for supersymmetry is presented based on events with at least one photon, jets, and large missing transverse momentum produced in proton–proton collisions at a center-of-mass energy of 13 Te . The data correspond to an integrated luminosity of 35.9 fb - 1 and were recorded at the LHC with the CMS detector in 2016. The analysis characterizes signal-like events by categorizing the data into various signal regions based on the number of jets, the number of b -tagged jets, and the missing transverse momentum. No significant excess of events is observed with respect to the expectations from standard model processes. Limits are placed on the gluino and top squark pair production cross sections using several simplified models of supersymmetric particle production with gauge-mediated supersymmetry breaking. Depending on the model and the mass of the next-to-lightest supersymmetric particle, the production of gluinos with masses as large as 2120 Ge and the production of top squarks with masses as large as 1230 Ge are excluded at 95% confidence level. [ABSTRACT FROM AUTHOR]

A measurement of the energy density in proton–proton collisions at a centre-of-mass energy of s = 13 TeV is presented. The data have been recorded with the CMS experiment at the LHC during low luminosity operations in 2015. The energy density is studied as a function of pseudorapidity in the ranges - 6.6 < η < - 5.2 and 3.15 < | η | < 5.20 . The results are compared with the predictions of several models. All the models considered suggest a different shape of the pseudorapidity dependence compared to that observed in the data. A comparison with LHC proton–proton collision data at s = 0.9 and 7 TeV confirms the compatibility of the data with the hypothesis of limiting fragmentation. [ABSTRACT FROM AUTHOR]

Combined measurements of the production and decay rates of the Higgs boson, as well as its couplings to vector bosons and fermions, are presented. The analysis uses the LHC proton–proton collision data set recorded with the CMS detector in 2016 at s = 13 Te , corresponding to an integrated luminosity of 35.9 fb - 1 . The combination is based on analyses targeting the five main Higgs boson production mechanisms (gluon fusion, vector boson fusion, and associated production with a W or Z boson, or a top quark-antiquark pair) and the following decay modes: H → γ γ Z Z W W τ τ b b , and μ μ . Searches for invisible Higgs boson decays are also considered. The best-fit ratio of the signal yield to the standard model expectation is measured to be μ = 1.17 ± 0.10 , assuming a Higgs boson mass of 125.09 Ge . Additional results are given for various assumptions on the scaling behavior of the production and decay modes, including generic parametrizations based on ratios of cross sections and branching fractions or couplings. The results are compatible with the standard model predictions in all parametrizations considered. In addition, constraints are placed on various two Higgs doublet models. [ABSTRACT FROM AUTHOR]

A search for the pair production of heavy vector-like partners T and B of the top and bottom quarks has been performed by the CMS experiment at the CERN LHC using proton–proton collisions at s = 13 Te . The data sample was collected in 2016 and corresponds to an integrated luminosity of 35.9 fb - 1 . Final states studied for T T ¯ production include those where one of the T quarks decays via T → t Z and the other via T → b W , t Z , or t H , where H is a Higgs boson. For the B B ¯ case, final states include those where one of the B quarks decays via B → b Z and the other B → t W , b Z , or b H . Events with two oppositely charged electrons or muons, consistent with coming from the decay of a Z boson, and jets are investigated. The number of observed events is consistent with standard model background estimations. Lower limits at 95% confidence level are placed on the masses of the T and B quarks for a range of branching fractions. Assuming 100% branching fractions for T → t Z , and B → b Z , T and B quark mass values below 1280 and 1130 Ge , respectively, are excluded. [ABSTRACT FROM AUTHOR]

A search is presented for resonant production of second-generation sleptons ( μ ~ L , ν ~ μ ) via the R-parity-violating coupling λ 211 ′ to quarks, in events with two same-sign muons and at least two jets in the final state. The smuon (muon sneutrino) is expected to decay into a muon and a neutralino (chargino), which will then decay into a second muon and at least two jets. The analysis is based on the 2016 data set of proton-proton collisions at s = 13 TeV recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 35.9 fb - 1 . No significant deviation is observed with respect to standard model expectations. Upper limits on cross sections, ranging from 0.24 to 730 fb , are derived in the context of two simplified models representing the dominant signal contributions leading to a same-sign muon pair. The cross section limits are translated into coupling limits for a modified constrained minimal supersymmetric model with λ 211 ′ as the only nonzero R-parity violating coupling. The results significantly extend restrictions of the parameter space compared with previous searches for similar models. [ABSTRACT FROM AUTHOR]

A top quark mass measurement is performed using 35.9 fb - 1 of LHC proton–proton collision data collected with the CMS detector at s = 13 TeV . The measurement uses the t t ¯ all-jets final state. A kinematic fit is performed to reconstruct the decay of the t t ¯ system and suppress the multijet background. Using the ideogram method, the top quark mass ( m t ) is determined, simultaneously constraining an additional jet energy scale factor (JSF ). The resulting value of m t = 172.34 ± 0.20 (stat+JSF) ± 0.70 (syst) GeV is in good agreement with previous measurements. In addition, a combined measurement that uses the t t ¯ lepton+jets and all-jets final states is presented, using the same mass extraction method, and provides an m t measurement of 172.26 ± 0.07 (stat+JSF) ± 0.61 (syst) GeV . This is the first combined m t extraction from the lepton+jets and all-jets channels through a single likelihood function. [ABSTRACT FROM AUTHOR]

The exclusive photoproduction of Υ (nS) meson states from protons, γ p → Υ (nS) p (with n = 1 , 2 , 3 ), is studied in ultraperipheral p Pb collisions at a centre-of-mass energy per nucleon pair of s NN = 5.02 TeV . The measurement is performed using the Υ (nS) → μ + μ - decay mode, with data collected by the CMS experiment corresponding to an integrated luminosity of 32.6 nb - 1 . Differential cross sections as functions of the Υ (nS) transverse momentum squared p T 2 , and rapidity y, are presented. The Υ (1 S) photoproduction cross section is extracted in the rapidity range | y | < 2.2 , which corresponds to photon–proton centre-of-mass energies in the range 91 < W γ p < 826 GeV . The data are compared to theoretical predictions based on perturbative quantum chromodynamics and to previous measurements. [ABSTRACT FROM AUTHOR]

Measurements are presented of associated production of a W boson and a charm quark ( W + c ) in proton–proton collisions at a center-of-mass energy of 13 Te . The data correspond to an integrated luminosity of 35.7 fb - 1 collected by the CMS experiment at the CERN LHC. The W bosons are identified by their decay into a muon and a neutrino. The charm quarks are tagged via the full reconstruction of D ∗ (2010) ± mesons that decay via D ∗ (2010) ± → D 0 + π ± → K ∓ + π ± + π ± . A cross section is measured in the fiducial region defined by the muon transverse momentum p T μ > 26 Ge , muon pseudorapidity | η μ | < 2.4 , and charm quark transverse momentum p T c > 5 Ge . The inclusive cross section for this kinematic range is σ (W + c) = 1026 ± 31 (stat) + 76 - 72 (syst) pb . The cross section is also measured differentially as a function of the pseudorapidity of the muon from the W boson decay. These measurements are compared with theoretical predictions and are used to probe the strange quark content of the proton. [ABSTRACT FROM AUTHOR]

A search for dark matter produced in association with a Higgs boson decaying to a pair of bottom quarks is performed in proton–proton collisions at a center-of-mass energy of 13 Te collected with the CMS detector at the LHC. The analyzed data sample corresponds to an integrated luminosity of 35.9 fb - 1 . The signal is characterized by a large missing transverse momentum recoiling against a bottom quark–antiquark system that has a large Lorentz boost. The number of events observed in the data is consistent with the standard model background prediction. Results are interpreted in terms of limits both on parameters of the type-2 two-Higgs doublet model extended by an additional light pseudoscalar boson a (2HDM+ a ) and on parameters of a baryonic Z ′ simplified model. The 2HDM+ a model is tested experimentally for the first time. For the baryonic Z ′ model, the presented results constitute the most stringent constraints to date. [ABSTRACT FROM AUTHOR]

A search is presented for a heavy spin-1 resonance Z ′ decaying to a top quark and a vector-like top quark partner T in the lepton + jets final state. The search is performed using a data set of p p collisions at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 35.9 fb - 1 as recorded by the CMS experiment at the CERN LHC in the year 2016. The analysis is optimised for final states arising from the T decay modes to a top quark and a Higgs or Z boson ( T → H t , Z t ). The event selection makes use of resolved and merged top quark decay products, as well as decays of boosted Higgs bosons and Z and W bosons using jet substructure techniques. No significant deviation from the standard model background expectation is observed. Exclusion limits on the product of the cross section and branching fraction for Z ′ → t T , T → H t , Z t , W b are presented for various combinations of the Z ′ resonance mass and the vector-like T quark mass. These results represent the most stringent limits to date for the decay mode Z ′ → t T → t H t . In a benchmark model with extra dimensions, invoking a heavy spin-1 resonance G ∗ , masses of the G ∗ between 1.5 and 2.3 TeV and between 2.0 and 2.4 TeV are excluded for T masses of 1.2 and 1.5 TeV , respectively. [ABSTRACT FROM AUTHOR]