Abstract A search for new long-lived particles decaying to leptons using proton–proton collision data produced by the CERN LHC at $$\sqrt{s}=13\,\text {Te}\text {V} $$ s = 13 Te is presented. Events ...are selected with two leptons (an electron and a muon, two electrons, or two muons) that both have transverse impact parameter values between 0.01 and 10 $$\,\text {cm}$$ cm and are not required to form a common vertex. Data used for the analysis were collected with the CMS detector in 2016, 2017, and 2018, and correspond to an integrated luminosity of 118 (113) $$\,\text {fb}^{-1}$$ fb - 1 in the $${{\mathrm{e}}_{\mathrm{}}^{\mathrm{}}} {{\mathrm{e}}_{\mathrm{}}^{\mathrm{}}} $$ e e channel ( $${{\mathrm{e}}_{\mathrm{}}^{\mathrm{}}} {\upmu } $$ e μ and $${\upmu } {\upmu } $$ μ μ channels). The search is designed to be sensitive to a wide range of models with displaced $${{\mathrm{e}}_{\mathrm{}}^{\mathrm{}}} {\upmu } $$ e μ , $${{\mathrm{e}}_{\mathrm{}}^{\mathrm{}}} {{\mathrm{e}}_{\mathrm{}}^{\mathrm{}}} $$ e e , and $${\upmu } {\upmu } $$ μ μ final states. The results constrain several well-motivated models involving new long-lived particles that decay to displaced leptons. For some areas of the available phase space, these are the most stringent constraints to date.
Abstract A combination of searches for top squark pair production using proton–proton collision data at a center-of-mass energy of 13 $$\,\text {Te}\text {V}$$ Te at the CERN LHC, corresponding to an ...integrated luminosity of 137 $$\,\text {fb}^{-1}$$ fb - 1 collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on the model, the combined result excludes a top squark mass up to 1325 $$\,\text {Ge}\text {V}$$ Ge for a massless neutralino, and a neutralino mass up to 700 $$\,\text {Ge}\text {V}$$ Ge for a top squark mass of 1150 $$\,\text {Ge}\text {V}$$ Ge . Top squarks with masses from 145 to 295 $$\,\text {Ge}\text {V}$$ Ge , for neutralino masses from 0 to 100 $$\,\text {Ge}\text {V}$$ Ge , with a mass difference between the top squark and the neutralino in a window of 30 $$\,\text {Ge}\text {V}$$ Ge around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 $$\,\text {Ge}\text {V}$$ Ge .
Abstract Results of the Model Unspecific Search in CMS (MUSiC), using proton–proton collision data recorded at the LHC at a centre-of-mass energy of 13 $$\,\text {TeV}$$ TeV , corresponding to an ...integrated luminosity of 35.9 $$\,\text {fb}^{-1}$$ fb - 1 , are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.
Abstract A search for charged Higgs bosons produced in vector boson fusion processes and decaying into vector bosons, using proton–proton collisions at $$\sqrt{s}=13\,{\text {TeV}} $$ s = 13 TeV at ...the LHC, is reported. The data sample corresponds to an integrated luminosity of 137 $$\,{\text {fb}}^{-1}$$ fb - 1 collected with the CMS detector. Events are selected by requiring two or three electrons or muons, moderate missing transverse momentum, and two jets with a large rapidity separation and a large dijet mass. No excess of events with respect to the standard model background predictions is observed. Model independent upper limits at 95% confidence level are reported on the product of the cross section and branching fraction for vector boson fusion production of charged Higgs bosons as a function of mass, from 200 to 3000 $$\,{\text {GeV}}$$ GeV . The results are interpreted in the context of the Georgi–Machacek model.
Abstract Production cross sections of the Higgs boson are measured in the $${\mathrm{H}} \rightarrow {\mathrm{Z}} {\mathrm{Z}} \rightarrow 4\ell $$ H → Z Z → 4 ℓ ( $$\ell ={\mathrm{e}},{{{\upmu ...}}_{\mathrm{}}^{\mathrm{}}} $$ ℓ = e , μ ) decay channel. A data sample of proton–proton collisions at a center-of-mass energy of 13 $$\,\text {Te}\text {V}$$ Te , collected by the CMS detector at the LHC and corresponding to an integrated luminosity of 137 $$\,\text {fb}^{-1}$$ fb - 1 is used. The signal strength modifier $$\mu $$ μ , defined as the ratio of the Higgs boson production rate in the $$4\ell $$ 4 ℓ channel to the standard model (SM) expectation, is measured to be $$\mu =0.94 \pm 0.07 \,\text {(stat)} ^{+0.09}_{-0.08} \,\text {(syst)} $$ μ = 0.94 ± 0.07 (stat) - 0.08 + 0.09 (syst) at a fixed value of $$m_{{\mathrm{H}}} = 125.38\,\text {Ge}\text {V} $$ m H = 125.38 Ge . The signal strength modifiers for the individual Higgs boson production modes are also reported. The inclusive fiducial cross section for the $${\mathrm{H}} \rightarrow 4\ell $$ H → 4 ℓ process is measured to be $$2.84^{+0.23}_{-0.22} \,\text {(stat)} ^{+0.26}_{-0.21} \,\text {(syst)} \,\text {fb} $$ 2 . 84 - 0.22 + 0.23 (stat) - 0.21 + 0.26 (syst) fb , which is compatible with the SM prediction of $$2.84 \pm 0.15 \,\text {fb} $$ 2.84 ± 0.15 fb for the same fiducial region. Differential cross sections as a function of the transverse momentum and rapidity of the Higgs boson, the number of associated jets, and the transverse momentum of the leading associated jet are measured. A new set of cross section measurements in mutually exclusive categories targeted to identify production mechanisms and kinematical features of the events is presented. The results are in agreement with the SM predictions.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract The production of Z boson pairs in proton–proton ( $${\mathrm{p}} {\mathrm{p}} $$ p p ) collisions, $${{\mathrm{p}} {\mathrm{p}} \rightarrow ({\mathrm{Z}}/\gamma ^*)({\mathrm{Z}}/\gamma ^*) ...\rightarrow 2\ell 2\ell '}$$ p p → ( Z / γ ∗ ) ( Z / γ ∗ ) → 2 ℓ 2 ℓ ′ , where $${\ell ,\ell ' = {\mathrm{e}}}$$ ℓ , ℓ ′ = e or $${{\upmu }}$$ μ , is studied at a center-of-mass energy of 13 $$\,\text {TeV}$$ TeV with the CMS detector at the CERN LHC. The data sample corresponds to an integrated luminosity of 137 $$\,\text {fb}^{-1}$$ fb - 1 , collected during 2016–2018. The $${\mathrm{Z}} {\mathrm{Z}} $$ Z Z production cross section, $$\sigma _{\text {tot}} ({\mathrm{p}} {\mathrm{p}} \rightarrow {\mathrm{Z}} {\mathrm{Z}} ) = 17.4 \pm 0.3 \,\text {(stat)} \pm 0.5 \,\text {(syst)} \pm 0.4 \,\text {(theo)} \pm 0.3 \,\text {(lumi)} \text { pb} $$ σ tot ( p p → Z Z ) = 17.4 ± 0.3 (stat) ± 0.5 (syst) ± 0.4 (theo) ± 0.3 (lumi) pb , measured for events with two pairs of opposite-sign, same-flavor leptons produced in the mass region $${60< m_{\ell ^+\ell ^-} < 120\,\text {GeV}}$$ 60 < m ℓ + ℓ - < 120 GeV is consistent with standard model predictions. Differential cross sections are also measured and agree with theoretical predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous $${\mathrm{Z}} {\mathrm{Z}} {\mathrm{Z}} $$ Z Z Z and $${{\mathrm{Z}} {\mathrm{Z}} \gamma }$$ Z Z γ couplings.
Abstract A search is presented for supersymmetric partners of the top quark (top squarks) in final states with two oppositely charged leptons (electrons or muons), jets identified as originating from ...$${\text {b}}$$ b quarks, and missing transverse momentum. The search uses data from proton-proton collisions at $$\sqrt{s}=13\,\text {TeV} $$ s = 13 TeV collected with the CMS detector, corresponding to an integrated luminosity of 137 $$\,{\text {fb}}^{-1}$$ fb - 1 . Hypothetical signal events are efficiently separated from the dominant top quark pair production background with requirements on the significance of the missing transverse momentum and on transverse mass variables. No significant deviation is observed from the expected background. Exclusion limits are set in the context of simplified supersymmetric models with pair-produced lightest top squarks. For top squarks decaying exclusively to a top quark and a lightest neutralino, lower limits are placed at $$95\%$$ 95 % confidence level on the masses of the top squark and the neutralino up to 925 and 450 $$\,\text {GeV}$$ GeV , respectively. If the decay proceeds via an intermediate chargino, the corresponding lower limits on the mass of the lightest top squark are set up to 850 $$\,\text {GeV}$$ GeV for neutralino masses below 420 $$\,\text {GeV}$$ GeV . For top squarks undergoing a cascade decay through charginos and sleptons, the mass limits reach up to 1.4 $$\,\text {TeV}$$ TeV and 900 $$\,\text {GeV}$$ GeV respectively for the top squark and the lightest neutralino.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The triple-differential dijet cross-section, d 3 σ e p / d Q 2 d E t ¯ 2 d x γ j e t s , is measured with the H1 detector at HERA as a function of the photon virtuality Q 2 , the fraction of the ...photon's momentum carried by the parton entering the hard scattering, \x γ j e t s , and the square of the mean transverse energy, E t ¯ 2 , of the two highest E t jets. Jets are found using a longitudinal boost-invariant k T clustering algorithm in the γ ∗ p center of mass frame. The measurements cover the ranges 1.6 < Q 2 < 80 GeV2 in virtuality and 0.1 < y < 0.7 in inelasticity y. The results are well described by leading order QCD models which include the effects of a resolved component to the virtual photon. Models which treat the photon as point-like fail to describe the data. An effective leading order parton density for the virtual photon is extracted as a function of the photon virtuality, the probing scale and the parton momentum fraction. The xγ and probing scale dependences of the parton density show characteristic features of photon structure, and a suppression of this structure with increasing Q 2 is seen.
Abstract A search for exotic decays of the Higgs boson ( $$\text {H}$$ H ) with a mass of 125 $$\,\text {Ge}\hspace{-.08em}\text {V}$$ Ge V to a pair of light pseudoscalars $$\text {a}_{1} $$ a 1 is ...performed in final states where one pseudoscalar decays to two $${\textrm{b}}$$ b quarks and the other to a pair of muons or $$\tau $$ τ leptons. A data sample of proton–proton collisions at $$\sqrt{s}=13\,\text {Te}\hspace{-.08em}\text {V} $$ s = 13 Te V corresponding to an integrated luminosity of 138 $$\,\text {fb}^{-1}$$ fb - 1 recorded with the CMS detector is analyzed. No statistically significant excess is observed over the standard model backgrounds. Upper limits are set at 95% confidence level ( $$\text {CL}$$ CL ) on the Higgs boson branching fraction to $$\upmu \upmu \text{ b } \text{ b } $$ μ μ b b and to $$\uptau \uptau \text{ b } \text{ b },$$ τ τ b b , via a pair of $$\text {a}_{1} $$ a 1 s. The limits depend on the pseudoscalar mass $$m_{\text {a}_{1}}$$ m a 1 and are observed to be in the range (0.17–3.3) $$\times 10^{-4}$$ × 10 - 4 and (1.7–7.7) $$\times 10^{-2}$$ × 10 - 2 in the $$\upmu \upmu \text{ b } \text{ b } $$ μ μ b b and $$\uptau \uptau \text{ b } \text{ b } $$ τ τ b b final states, respectively. In the framework of models with two Higgs doublets and a complex scalar singlet (2HDM+S), the results of the two final states are combined to determine upper limits on the branching fraction $${\mathcal {B}}(\text {H} \rightarrow \text {a}_{1} \text {a}_{1} \rightarrow \ell \ell \text{ b } \text{ b})$$ B ( H → a 1 a 1 → ℓ ℓ b b ) at 95% $$\text {CL}$$ CL , with $$\ell $$ ℓ being a muon or a $$\uptau $$ τ lepton. For different types of 2HDM+S, upper bounds on the branching fraction $${\mathcal {B}}(\text {H} \rightarrow \text {a}_{1} \text {a}_{1} )$$ B ( H → a 1 a 1 ) are extracted from the combination of the two channels. In most of the Type II 2HDM+S parameter space, $${\mathcal {B}}(\text {H} \rightarrow \text {a}_{1} \text {a}_{1} )$$ B ( H → a 1 a 1 ) values above 0.23 are excluded at 95% $$\text {CL}$$ CL for $$m_{\text {a}_{1}}$$ m a 1 values between 15 and 60 $$\,\text {Ge}\hspace{-.08em}\text {V}$$ Ge V .
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract A search for a new boson X is presented using CERN LHC proton-proton collision data collected by the CMS experiment at s $$ \sqrt{s} $$ = 13 TeV in 2016–2018, and corresponding to an ...integrated luminosity of 138 fb −1. The resonance X decays into either a pair of Higgs bosons HH of mass 125 GeV or an H and a new spin-0 boson Y. One H subsequently decays to a pair of photons, and the second H or Y, to a pair of bottom quarks. The explored mass ranges of X are 260–1000 GeV and 300–1000 GeV, for decays to HH and to HY, respectively, with the Y mass range being 90–800 GeV. For a spin-0 X hypothesis, the 95% confidence level upper limit on the product of its production cross section and decay branching fraction is observed to be within 0.90–0.04 fb, depending on the masses of X and Y. The largest deviation from the background-only hypothesis with a local (global) significance of 3.8 (below 2.8) standard deviations is observed for X and Y masses of 650 and 90 GeV, respectively. The limits are interpreted using several models of new physics.
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