Date

Collaboration

Phrases

Reactions

Search for physics beyond the standard model in multilepton final states in proton-proton collisions at $\sqrt{s} =$ 13 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
No Journal Information, 2019.
Inspire Record 1764474 DOI 10.17182/hepdata.91969

A search for physics beyond the standard model in events with at least three charged leptons (electrons or muons) is presented. The data sample corresponds to an integrated luminosity of 137 fb$^{-1}$ of proton-proton collisions at $\sqrt{s} =$ 13 TeV, collected with the CMS detector at the LHC in 2016-2018. The two targeted signal processes are pair production of type-III seesaw heavy fermions and production of a light scalar or pseudoscalar boson in association with a pair of top quarks. The heavy fermions may be manifested as an excess of events with large values of leptonic transverse momenta or missing transverse momentum. The light scalars or pseudoscalars may create a localized excess in the dilepton mass spectra. The results exclude heavy fermions of the type-III seesaw model for masses below 880 GeV at 95% confidence level in the scenario of equal branching fractions to each lepton flavor. This is the most restrictive limit on the flavor-democratic scenario of the type-III seesaw model to date. Assuming a Yukawa coupling of unit strength to top quarks, branching fractions of new scalar (pseudoscalar) bosons to dielectrons or dimuons above 0.004 (0.03) and 0.04 (0.03) are excluded at 95% confidence level for masses in the range 15-75 and 108-340 GeV, respectively. These are the first limits in these channels on an extension of the standard model with scalar or pseudoscalar particles.

58 data tables

The 95% confidence level exclusion limits for the flavor-democratic scenario on the total production cross section of heavy fermion pairs.

The dimuon $M_{OSSF}^{20}$ distribution in the 4L($\mu\mu$) 0B, $S_{T}$<400 GeV signal region. The last bin does not contain the overflow events. The signal is shown with $g_{t}^2\mathcal{B}(\phi - {\mu\mu})$=0.05.

The dimuon $M_{OSSF}^{300}$ distribution in the 4L($\mu\mu$) 0B, $S_{T}$<400 GeV signal region. The last bin does not contain the overflow events. The signal is shown with $g_{t}^2\mathcal{B}(\phi - {\mu\mu})$=0.05.

More…

Search for a heavy pseudoscalar Higgs boson decaying into a 125 GeV Higgs boson and a Z boson in final states with two tau and two light leptons at $\sqrt{s}=$ 13 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
No Journal Information, 2019.
Inspire Record 1761088 DOI 10.17182/hepdata.90685

A search is performed for a pseudoscalar Higgs boson, A, decaying into a 125 GeV Higgs boson h and a Z boson. The h boson is specifically targeted in its decay into a pair of tau leptons, while the Z boson decays into a pair of electrons or muons. A data sample of proton-proton collisions collected by the CMS experiment at the LHC at $\sqrt{s} =$ 13 TeV is used, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. No excess above the standard model background expectations is observed in data. A model-independent upper limit is set on the product of the gluon fusion production cross section for the A boson and the branching fraction to Zh$\to\ell\ell\tau\tau$. The observed upper limit at 95% confidence level ranges from 27 to 5 fb for A boson masses from 220 to 400 GeV, respectively. The results are used to constrain the extended Higgs sector parameters for two benchmark scenarios of the minimal supersymmetric standard model.

1 data table

The expected and observed 95% CL model-independent upper limits on the product of the cross section and branching fraction for the A boson (pseudoscalar Higgs boson).


Measurement of the $ Z\gamma \to \nu \overline{\nu}\gamma $ production cross section in pp collisions at $ \sqrt{s}=13 $ TeV with the ATLAS detector and limits on anomalous triple gauge-boson couplings

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
JHEP 1812 (2018) 010, 2018.
Inspire Record 1698006 DOI 10.17182/hepdata.83965

The production of Z bosons in association with a high-energy photon (Zγ production) is studied in the neutrino decay channel of the Z boson using pp collisions at $ \sqrt{s}=13 $ TeV. The analysis uses a data sample with an integrated luminosity of 36.1fb$^{−1}$ collected by the ATLAS detector at the LHC in 2015 and 2016. Candidate Zγ events with invisible decays of the Z boson are selected by requiring significant transverse momentum (p$_{T}$) of the dineutrino system in conjunction with a single isolated photon with large transverse energy (E$_{T}$). The rate of Zγ production is measured as a function of photon E$_{T}$, dineutrino system p$_{T}$ and jet multiplicity. Evidence of anomalous triple gauge-boson couplings is sought in Zγ production with photon E$_{T}$ greater than 600 GeV. No excess is observed relative to the Standard Model expectation, and upper limits are set on the strength of ZZγ and Zγγ couplings.

8 data tables

Measured integrated cross sections for the $Z\gamma$ process for neutrino final states at $\sqrt{s} = 13$ TeV in the extended fiducial region defined in the paper.

Measured differential cross sections for the $pp \rightarrow \nu\bar{\nu}\gamma$ process at $\sqrt{s} = 13$ TeV as a function of photon $E_{T}$ in the inclusive $N_{jets} \geq 0$ extended fiducial region defined in the paper.

Measured differential cross sections for the $pp \rightarrow \nu\bar{\nu}\gamma$ process at $\sqrt{s} = 13$ TeV as a function of photon $E_{T}$ in the exclusive $N_{jets} = 0$ extended fiducial region defined in the paper.

More…

Search for associated production of a Higgs boson and a single top quark in proton-proton collisions at $\sqrt{s} =$ TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Rev. D99 (2019) 092005, 2019.
Inspire Record 1704945 DOI 10.17182/hepdata.90686

A search is presented for the production of a Higgs boson in association with a single top quark, based on data collected in 2016 by the CMS experiment at the LHC at a center-of-mass energy of 13 TeV, which corresponds to an integrated luminosity of 35.9  fb-1. The production cross section for this process is highly sensitive to the absolute values of the top quark Yukawa coupling, yt; the Higgs boson coupling to vector bosons, gHVV; and, uniquely, their relative sign. Analyses using multilepton signatures, targeting H→WW, H→ττ, and H→ZZ decay modes, and signatures with a single lepton and a bb¯ pair, targeting the H→bb¯ decay, are combined with a reinterpretation of a measurement in the H→γγ channel to constrain yt. For a standard model–like value of gHVV, the data favor positive values of yt and exclude values of yt below about -0.9ytSM.

2 data tables

Expected and observed 95% CL upper limits on the tH production cross section times $H \to WW/ZZ/\tau\tau/b\bar{b}/\gamma\gamma$ branching fraction for a scenario of inverted couplings ($\kappa_t=-1.0$ and $\kappa_V=1.0$, top rows), vanishing top quark Yukawa coupling ($\kappa_t=0.0$ and $\kappa_V=1.0$, middle rows), and for an SM-like signal ($\kappa_t=1.0$ and $\kappa_V=1.0$, bottom rows), in pb. The Higgs to vector boson couplings is considered to be SM-like. The expected limit is calculated on a background-only data set, i.e., without tH contribution, but including a coupling dependent contribution from the ttH production. The ttH normalization is kept fixed in the fit, while the tH cross section is allowed to float. Limits can be compared to the expected product of tH cross sections and branching fractions of 0.83, 0.28, and 0.077 pb for the inverted top quark Yukawa coupling, the vanishing top-Yukawa and the SM-like scenario.

Observed and expected 95% CL upper limit on the tH cross section times combined $HH \to WW/ZZ/\tau\tau/b\bar{b}/\gamma\gamma$ branching fraction for different values of the top-Yukawa coupling modifier, assuming SM-like Higgs to vector boson couplings. The expected limit is calculated on a background-only data set, i.e., without tH contribution, but including a coupling dependent contribution from the ttH production. The ttH normalization is kept fixed in the fit, while the tH cross section is allowed to float.


Measurement of $W^{\pm}Z$ production cross sections and gauge boson polarisation in $pp$ collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Eur.Phys.J. C79 (2019) 535, 2019.
Inspire Record 1720438 DOI 10.17182/hepdata.83701

This paper presents measurements of $W^{\pm }Z$ production cross sections in pp collisions at a centre-of-mass energy of 13  $\text {TeV}$ . The data were collected in 2015 and 2016 by the ATLAS experiment at the Large Hadron Collider, and correspond to an integrated luminosity of $36.1~\hbox {fb}^{-1}$ . The $W^{\pm }Z$ candidate events are reconstructed using leptonic decay modes of the gauge bosons into electrons and muons. The measured inclusive cross section in the detector fiducial region for a single leptonic decay mode is $\sigma _{W^\pm Z \rightarrow \ell ^{'} \nu \ell \ell }^{\text {fid.}} = 63.7 \, \pm ~1.0~\text {(stat.)} \, \pm ~2.3~\text {(syst.)} \, \pm ~1.4~\text {(lumi.)}$  fb, reproduced by the next-to-next-to-leading-order Standard Model prediction of $61.5^{+1.4-1.3}$  fb. Cross sections for $W^+Z$ and $W^-Z$ production and their ratio are presented as well as differential cross sections for several kinematic observables. An analysis of angular distributions of leptons from decays of W and Z bosons is performed for the first time in pair-produced events in hadronic collisions, and integrated helicity fractions in the detector fiducial region are measured for the W and Z bosons separately. Of particular interest, the longitudinal helicity fraction of pair-produced vector bosons is also measured.

24 data tables

The measured $W^{\pm}Z$ fiducial cross section in the four channels and their combination. The first systematic uncertainty is the combined systematic uncertainty excluding luminosity uncertainty, the second is the modelling uncertainty, the third is luminosity uncertainty.

The measured $W^{+}Z$ fiducial cross section in the four channels and their combination. The first systematic uncertainty is the combined systematic uncertainty excluding luminosity uncertainty, the second is the modelling uncertainty, the third is luminosity uncertainty.

The measured $W^{-}Z$ fiducial cross section in the four channels and their combination. The first systematic uncertainty is the combined systematic uncertainty excluding luminosity uncertainty, the second is the modelling uncertainty, the third is luminosity uncertainty.

More…

Search for squarks and gluinos in final states with same-sign leptons and jets using 139 fb$^{-1}$ of data collected with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
No Journal Information, 2019.
Inspire Record 1754675 DOI 10.17182/hepdata.91214

A search for supersymmetric partners of gluons and quarks is presented, involving signatures with jets and either two isolated leptons (electrons or muons) with the same electric charge, or at least three isolated leptons. A data sample of proton-proton collisions at $\sqrt{s}$ = 13 TeV recorded with the ATLAS detector at the Large Hadron Collider between 2015 and 2018, corresponding to a total integrated luminosity of 139 fb$^{-1}$, is used for the search. No significant excess over the Standard Model expectation is observed. The results are interpreted in simplified supersymmetric models featuring both R-parity conservation and R-parity violation, raising the exclusion limits beyond those of previous ATLAS searches to 1600 GeV for gluino masses and 750 GeV for bottom and top squark masses in these scenarios.

30 data tables

Best observed 95% CL exclusion contours selected from Rpc2L1b and Rpc2L2b on the lightest bottom squark and lightest neutralino masses in a SUSY scenario where pairs of bottom-antibottom squarks are produced and decay into the lightest neutralino via a chargino, $\tilde b^{}_{1}\to t\tilde{\chi}_1^-$ followed by $\tilde{\chi}_1^\pm\to W^\pm\tilde{\chi}_1^0$.

Number of signal events expected for 139 fb$^{-1}$ at different stages of the event selection for the signal region Rpc2L0b, in a SUSY scenario where gluinos are produced in pairs and decay into the lightest neutralino via a two-steps cascade, $\tilde g\to q\bar{q}^{'}\tilde{\chi}_1^\pm$ followed by $\tilde{\chi}_1^\pm\to W^\pm\tilde{\chi}_2^0$ and $\tilde{\chi}_2^0\to Z\tilde{\chi}_1^0$. The masses of the superpartners involved in the process are set to $m(\tilde g)$ = 1600 GeV, $m(\tilde \chi_1^\pm)$ = 1200 GeV, $m(\tilde \chi_2^0)$ = 1000 GeV and $m(\tilde \chi_1^0)$ = 800 GeV. Only statistical uncertainties are shown.

Number of signal events expected for 139 fb$^{-1}$ at different stages of the event selection for the signal region Rpc2L1b, in a SUSY scenario where pairs of bottom-antibottom squarks are produced and decay into the lightest neutralino via a chargino, $\tilde b^{}_{1}\to t\tilde{\chi}_1^-$ followed by $\tilde{\chi}_1^\pm\to W^\pm\tilde{\chi}_1^0$. The masses of the superpartners involved in the process are set to $m(\tilde{b}^{}_1)$ = 850 GeV, $m(\tilde \chi_1^\pm)$ = 500 GeV and $m(\tilde \chi_1^0)$ = 400 GeV. Only statistical uncertainties are shown.

More…

Measurement of charged jet cross section in pp collisions at ${\sqrt{s}=5.02}$ TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adhya, Souvik Priyam ; et al.
No Journal Information, 2019.
Inspire Record 1733689 DOI 10.17182/hepdata.91239

The cross section of jets reconstructed from charged particles is measured in the transverse momentum range of $5<p_\mathrm{T}<100\ \mathrm{GeV}/c$ in pp collisions at the center-of-mass energy of $\sqrt{s} = 5.02\ \mathrm{TeV}$ with the ALICE detector. The jets are reconstructed using the anti-$k_\mathrm{T}$ algorithm with resolution parameters $R=0.2$, $0.3$, $0.4$, and $0.6$ in the pseudorapidity range $|\eta|< 0.9-R$. The charged jet cross sections are compared with the leading order (LO) and to next-to-leading order (NLO) perturbative Quantum ChromoDynamics (pQCD) calculations. It was found that the NLO calculations agree better with the measurements. The cross section ratios for different resolution parameters were also measured. These ratios increase from low $p_\mathrm{T}$ to high $p_\mathrm{T}$ and saturate at high $p_\mathrm{T}$, indicating that jet collimation is larger at high $p_\mathrm{T}$ than at low $p_\mathrm{T}$. These results provide a precision test of pQCD predictions and serve as a baseline for the measurement in Pb$-$Pb collisions at the same energy to quantify the effects of the hot and dense medium created in heavy-ion collisions at the LHC.

4 data tables

Charged jet differential cross sections without UE subtraction in pp collisions at $\sqrt{s}$ = 5.02 TeV with the leading track bias. All jets must contain at least one track with $p_{T}$ > 5 GeV/$c$. Statistical uncertainties are displayed as vertical error bars. The total systematic uncertainties are shown as shaded bands around the data points. Data are scaled to enhance visibility

Fig. 6: Charged jet cross section ratios for $\\sigma$(R = 0.2)/$\\sigma$(R = 0.4) (Red) and $\\sigma$(R = 0.2)/$\\sigma$(R = 0.6). The systematic uncertainty of the cross section ratio is indicated by a shaded band drawn around data points.

Fig. 3: Fully corrected charged jet differential cross sections in pp collisions at $\\sqrt{s}$ = 5.02 TeV. Statistical uncertainties are displayed as vertical error bars. The total systematic uncertainties are shown as shaded bands around the data points. Data are scaled to enhance visibility.

More…

Measurement of prompt photon production in $\sqrt{s_\mathrm{NN}} = 8.16$ TeV $p$+Pb collisions with ATLAS

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Lett. B796 (2019) 230-252, 2019.
Inspire Record 1723858 DOI 10.17182/hepdata.87256

The inclusive production rates of isolated, prompt photons in p+Pb collisions at sNN=8.16 TeV are studied with the ATLAS detector at the Large Hadron Collider using a dataset with an integrated luminosity of 165 nb −1 recorded in 2016. The cross-section and nuclear modification factor RpPb are measured as a function of photon transverse energy from 20 GeV to 550 GeV and in three nucleon–nucleon centre-of-mass pseudorapidity regions, (−2.83,−2.02) , (−1.84,0.91) , and (1.09,1.90) . The cross-section and RpPb values are compared with the results of a next-to-leading-order perturbative QCD calculation, with and without nuclear parton distribution function modifications, and with expectations based on a model of the energy loss of partons prior to the hard scattering. The data disfavour a large amount of energy loss and provide new constraints on the parton densities in nuclei.

7 data tables

The measured cross sections for prompt, isolated photons with rapidity in (1.09,1.90).

The measured cross sections for prompt, isolated photons with rapidity in (−1.84,0.91).

The measured cross sections for prompt, isolated photons with rapidity in (−2.83,−2.02).

More…

Measurement of the associated production of a single top quark and a Z boson in pp collisions at $\sqrt{s} =$ 13 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Lett. B779 (2018) 358-384, 2018.
Inspire Record 1642230 DOI 10.17182/hepdata.81680

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 s=13TeV 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 σ(pp→tZq→Wbℓ+ℓ−q)=123−31+33(stat)−23+29(syst)fb , where ℓ stands for electrons, muons, or τ leptons, with observed and expected significances of 3.7 and 3.1 standard deviations, respectively.

1 data table

The measured cross section, with statistical and systematic uncertainties. The observed significance. The expected significance


Observation of electroweak production of a same-sign $W$ boson pair in association with two jets in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
No Journal Information, 2019.
Inspire Record 1738841 DOI 10.17182/hepdata.84643

This Letter presents the observation and measurement of electroweak production of a same-sign $W$ boson pair in association with two jets using 36.1 fb$^{-1}$ of proton-proton collision data recorded at a center-of-mass energy of $\sqrt{s}=13$ TeV by the ATLAS detector at the Large Hadron Collider. The analysis is performed in the detector fiducial phase-space region, defined by the presence of two same-sign leptons, electron or muon, and at least two jets with a large invariant mass and rapidity difference. A total of 122 candidate events are observed for a background expectation of $69 \pm 7$ events, corresponding to an observed signal significance of 6.5 standard deviations. The measured fiducial signal cross section is $\sigma^{\mathrm {fid.}}=2.89^{+0.51}_{-0.48} \mathrm{(stat.)} ^{+0.29}_{-0.28} \mathrm{(syst.)}$ fb.

6 data tables

Measured fiducial cross section.

The $m_{jj}$ distribution for events meeting all selection criteria for the signal region. Signal and individual background distributions are shown as predicted after the fit. The last bin includes the overflow. The highest value measured in a candidate event in data is $m_{jj}=3.8$ TeV.

The $m_{ll}$ distribution for events meeting all selection criteria for the signal region as predicted after the fit. The fitted signal strength and nuisance parameters have been propagated, with the exception of the uncertainties due to the interference and electroweak corrections for which a flat uncertainty is assigned. The last bin includes the overflow. The highest value measured in a candidate event in data is $m_{ll}=824$ GeV.

More…

Search for an exotic decay of the Higgs boson to a pair of light pseudoscalars in the final state with two muons and two b quarks in pp collisions at 13 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Lett. B795 (2019) 398-423, 2019.
Inspire Record 1709317 DOI 10.17182/hepdata.91235

A search for exotic decays of the Higgs boson to a pair of light pseudoscalar particles a$_1$ is performed under the hypothesis that one of the pseudoscalars decays to a pair of opposite sign muons and the other decays to b$\overline{\mathrm{b}}$. Such signatures are predicted in a number of extensions of the standard model (SM), including next-to-minimal supersymmetry and two-Higgs-doublet models with an additional scalar singlet. The results are based on a data set of proton-proton collisions corresponding to an integrated luminosity of 35.9 fb$^{-1}$, accumulated with the CMS experiment at the CERN LHC in 2016 at a centre-of-mass energy of 13 TeV. No statistically significant excess is observed with respect to the SM backgrounds in the search region for pseudoscalar masses from 20 GeV to half of the Higgs boson mass. Upper limits at 95% confidence level are set on the product of the production cross section and branching fraction, $\sigma_{\mathrm{h}}\mathcal{B}$(h $\to$ a$_1$ a$_1$ $\to$ $\mu^+\mu^-\mathrm{b}\bar{\mathrm{b}}$), ranging from 5 to 33 fb, depending on the pseudoscalar mass. Corresponding limits on the branching fraction, assuming the SM prediction for $\sigma_{\mathrm{h}}$, are (1$-$7)$\times$ 10$^{-4}$.

2 data tables

Observed and expected upper limits at 95% CL on the product of the Higgs boson production cross section and B(h->aa->mumubb)

Observed and expected upper limits at 95% CL on the branching fraction of (h->aa->mumubb)


Measurement of the inclusive cross-section for the production of jets in association with a Z boson in proton-proton collisions at 8 TeV using the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
No Journal Information, 2019.
Inspire Record 1744201 DOI 10.17182/hepdata.90953

The inclusive cross-section for jet production in association with a Z boson decaying into an electron-positron pair is measured as a function of the transverse momentum and the absolute rapidity of jets using 19.9 fb$^{-1}$ of $\sqrt s = 8$ TeV proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider. The measured Z + jets cross-section is unfolded to the particle level. The cross-section is compared with state-of-the-art Standard Model calculations, including the next-to-leading-order and next-to-next-to-leading-order perturbative QCD calculations, corrected for non-perturbative and QED radiation effects. The results of the measurements cover final-state jets with transverse momenta up to 1 TeV, and show good agreement with fixed-order calculations.

20 data tables

List of experimentally considered systematic uncertainties for the Z + jets cross-section measurement

The double-differential Z + jets production cross-section as a function of |y_{jet}| in the 25 GeV < p_{T}^{jet} < 50 GeV range. The particle level phase space definition: - 66 GeV < m_{ee} < 116 GeV - |eta_{electron}| < 2.47 - p_{T}^{electron} > 20 GeV - anti-kt R=0.4 jets N>=1 - |y_{jet}| < 3.4 - p_{T}^{jet} > 25 GeV - Delta R(jet, electron) > 0.4

The double-differential Z + jets production cross-section as a function of |y_{jet}| in the 50 GeV < p_{T}^{jet} < 100 GeV range. The particle level phase space definition: - 66 GeV < m_{ee} < 116 GeV - |eta_{electron}| < 2.47 - p_{T}^{electron} > 20 GeV - anti-kt R=0.4 jets N>=1 - |y_{jet}| < 3.4 - p_{T}^{jet} > 25 GeV - Delta R(jet, electron) > 0.4

More…

Search for light long-lived neutral particles produced in $pp$ collisions at $\sqrt{s} =$ 13 TeV and decaying into collimated leptons or light hadrons with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
No Journal Information, 2019.
Inspire Record 1752519 DOI 10.17182/hepdata.91132

Several models of physics beyond the Standard Model predict the existence of dark photons, light neutral particles decaying into collimated leptons or light hadrons. This paper presents a search for long-lived dark photons produced from the decay of a Higgs boson or a heavy scalar boson and decaying into displaced collimated Standard Model fermions. The search uses data corresponding to an integrated luminosity of 36.1 fb$^{-1}$ collected in proton-proton collisions at $\sqrt{s} =$ 13 TeV recorded in 2015-2016 with the ATLAS detector at the Large Hadron Collider. The observed number of events is consistent with the expected background, and limits on the production cross section times branching fraction as a function of the proper decay length of the dark photon are reported. A cross section times branching fraction above 4 pb is excluded for a Higgs boson decaying into two dark photons for dark-photon decay lengths between 1.5 mm and 307 mm.

19 data tables

Upper limits at 95% CL on the cross section times branching fraction for the process $H \to 2\gamma_d + X$ with $m_H$ = 125 GeV in the muon-muon final state.

Upper limits at 95% CL on the cross section times branching fraction for the process $H \to 4\gamma_d + X$ with $m_H$ = 125 GeV in the muon-muon final state.

Upper limits at 95% CL on the cross section times branching fraction for the process $H \to 2\gamma_d + X$ with $m_H$ = 800 GeV in the muon-muon final state.

More…

Version 2
Search for long-lived particles using nonprompt jets and missing transverse momentum with proton-proton collisions at $\sqrt{s} =$ 13 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Lett. B797 (2019) 134876, 2019.
Inspire Record 1740108 DOI 10.17182/hepdata.90583

A search for long-lived particles decaying to displaced, nonprompt jets and missing transverse momentum is presented. The data sample corresponds to an integrated luminosity of 137 fb$^{-1}$ of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment at the CERN LHC in 2016-2018. Candidate signal events containing nonprompt jets are identified using the timing capabilities of the CMS electromagnetic calorimeter. The results of the search are consistent with the background prediction and are interpreted using a gauge-mediated supersymmetry breaking reference model with a gluino next-to-lightest supersymmetric particle. In this model, gluino masses up to 2100, 2500, and 1900 GeV are excluded at 95% confidence level for proper decay lengths of 0.3, 1, and 100 m, respectively. These are the best limits to date for such massive gluinos with proper decay lengths greater than $\sim$0.5 m.

28 data tables

The distribution (normalized to unity) of number of ECAL cells hit in the jet for jets in a background enriched data sample (satisfying $|\eta| < 1.48$, $PV_{\rm track}^{\rm fraction} > 1/12$, $\mathrm{HEF} > 0.2$, $t_{\mathrm{jet}} < -3\,\mathrm{ns}$ and $E^{\mathrm{CSC}}_\mathrm{ECAL}/E_{\mathrm{ECAL}} < 0.8$) and for signal jets satisfying signal region requirements (except those on $E_{\mathrm{ECAL}}$ and $N^{\mathrm{cell}}_{\mathrm{ECAL}}$).

Selection efficiencies for the GMSB model with $m_{\tilde{g}}=1000$ and various proper decay lengths

Summary of the estimated number of background events.

More…

Evidence for the production of three massive vector bosons with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
No Journal Information, 2019.
Inspire Record 1726499 DOI 10.17182/hepdata.89323

A search for the production of three massive vector bosons in proton-proton collisions is performed using data at $\sqrt{s} = 13$ TeV recorded with the ATLAS detector at the Large Hadron Collider in the years 2015-2017, corresponding to an integrated luminosity of $79.8$ fb$^{-1}$. Events with two same-sign leptons $\ell$ (electrons or muons) and at least two reconstructed jets are selected to search for $WWW \to \ell \nu \ell \nu qq$. Events with three leptons without any same-flavour opposite-sign lepton pairs are used to search for $WWW \to \ell \nu \ell\nu \ell \nu$, while events with three leptons and at least one same-flavour opposite-sign lepton pair and one or more reconstructed jets are used to search for $WWZ \to \ell \nu qq \ell \ell$. Finally, events with four leptons are analysed to search for $WWZ \to \ell \nu \ell \nu \ell \ell$ and $WZZ \to qq \ell \ell \ell \ell$. Evidence for the joint production of three massive vector bosons is observed with a significance of 4.1 standard deviations, where the expectation is 3.1 standard deviations.

2 data tables

Measurement of the $WWW$ cross section.

Measurement of the $WWZ$ cross section.


Measurement of the cross-section and charge asymmetry of $W$ bosons produced in proton-proton collisions at $\sqrt{s}=8$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
Eur.Phys.J., 2019.
Inspire Record 1729240 DOI 10.17182/hepdata.89322

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of $20.2~\mbox{fb$^{-1}$}$. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.

8 data tables

Cross-sections (differential in $\eta_{\mu}$) and asymmetry, as a function of $|\eta_{\mu}|$). The central values are provided along with the statistical and dominant systematic uncertainties: the data statistical uncertainty (Data Stat.), the $E_T^{\textrm{miss}}$ uncertainty, the uncertainties related to muon reconstruction (Muon Reco.), those related to the background, those from MC statistics (MC Stat.), and modelling uncertainties. The uncertainties of the cross-sections are given in percent and those of the asymmetry as an absolute difference from the nominal.

The correction factors, $C_{W^±,i}$ with their associated systematic uncertainties as a function of $|\eta_{\mu}|$, for $W^+$ and $W^−$

The integrated global correction factor $C_{W^±}$, for $W^+$ and $W^−$

More…

Search for light pseudoscalar boson pairs produced from decays of the 125 GeV Higgs boson in final states with two muons and two nearby tracks in pp collisions at $\sqrt{s}=$ 13 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
No Journal Information, 2019.
Inspire Record 1744267 DOI 10.17182/hepdata.90694

A search is presented for pairs of light pseudoscalar bosons, in the mass range from 4 to 15 GeV, produced from decays of the 125 GeV Higgs boson. The decay modes considered are final states that arise when one of the pseudoscalars decays to a pair of tau leptons, and the other one either into a pair of tau leptons or muons. The search is based on proton-proton collisions collected by the CMS experiment in 2016 at a center-of-mass energy of 13 TeV that correspond to an integrated luminosity of 35.9 fb${-1}$. The 2$\mu$2$\tau$ and 4$\tau$ channels are used in combination to constrain the product of the Higgs boson production cross section and the branching fraction into 4$\tau$ final state, $\sigma\mathcal{B}$, exploiting the linear dependence of the fermionic coupling strength of pseudoscalar bosons on the fermion mass. No significant excess is observed beyond the expectation from the standard model. The observed and expected upper limits at 95% confidence level on $\sigma\mathcal{B}$, relative to the standard model Higgs boson production cross section, are set respectively between 0.022 and 0.23 and between 0.027 and 0.19 in the mass range probed by the analysis.

1 data table

Expected and observed 95% CL upper limits on (sigma(pp->h)/sigma(pp->hSM)) * B(h -> aa -> tautautautau) as a function of m(a) obtained from the 13 TeV data, where h(SM) is the Higgs boson of the standard model, h is the observed particle with mass of 125 GeV, and (a) denotes a light Higgs-like state.


Version 2
Search for heavy charged long-lived particles in the ATLAS detector in 36.1 fb$^{-1}$ of proton-proton collision data at $\sqrt{s} = 13$ TeV

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Rev. D99 (2019) 092007, 2019.
Inspire Record 1718558 DOI 10.17182/hepdata.86565

A search for heavy charged long-lived particles is performed using a data sample of 36.1  fb−1 of proton-proton collisions at s=13  TeV collected by the ATLAS experiment at the Large Hadron Collider. The search is based on observables related to ionization energy loss and time of flight, which are sensitive to the velocity of heavy charged particles traveling significantly slower than the speed of light. Multiple search strategies for a wide range of lifetimes, corresponding to path lengths of a few meters, are defined as model independently as possible, by referencing several representative physics cases that yield long-lived particles within supersymmetric models, such as gluinos/squarks (R-hadrons), charginos and staus. No significant deviations from the expected Standard Model background are observed. Upper limits at 95% confidence level are provided on the production cross sections of long-lived R-hadrons as well as directly pair-produced staus and charginos. These results translate into lower limits on the masses of long-lived gluino, sbottom and stop R-hadrons, as well as staus and charginos of 2000, 1250, 1340, 430, and 1090 GeV, respectively.

30 data tables

Lower mass requirement for signal regions.

Lower mass requirement for signal regions.

Expected and observed events in the 16 discovery regions along with the according control regions.

More…

Search for new phenomena in events with missing transverse momentum and a Higgs boson decaying into two photons at $\sqrt{s}$ = 13 TeV with the ATLAS detector

The ATLAS collaboration
No Journal Information, 2017.
Inspire Record 1589907 DOI 10.17182/hepdata.80077

A search for new phenomena in events with missing transverse momentum and a Standard Model (SM) Higgs boson decaying into two photons is presented. This study is based on data collected with the ATLAS detector corresponding to an integrated luminosity of $36.1~\mathrm{fb}^{-1}$ of proton-proton collisions at the LHC at a center-of-mass energy of 13 TeV in 2015 and 2016. No significant excess over the background expectation is observed. 95% confidence level limits are set on the production cross section times branching fraction of the SM Higgs boson decaying into two photons in association with missing transverse momentum in three different theoretical benchmark models. 95% confidence level limits are also set on the observed signal strength in a two-dimensional plane using masses of benchmark models particles. Additionally, the results are interpreted in terms of 90% confidence level limits on the dark matter-nucleon scattering cross section, as a function of the dark matter particle mass, for a spin-independent scenario.

3 data tables

The missing energy significance distribution between data and MC. the MET significance is defined as the MET divided by the SumET. SumET is the total transverse energy calculated from the scalar sum of the transverse momenta of the calibrated photons, electrons, muons and jets used in the MET calculation.

The diphoton pT distribution of the data and MC.

The pT hard distribution of the data and MC. The pT hard means the vectorial sum of all hard objects, like photons, leptons and jets. The jets pT are required to be greater than 25 GeV.


Search for a heavy charged boson in events with a charged lepton and missing transverse momentum from $pp$ collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
No Journal Information, 2019.
Inspire Record 1739784 DOI 10.17182/hepdata.90193

A search for a heavy charged-boson resonance decaying into a charged lepton (electron or muon) and a neutrino is reported. A data sample of 139 fb$^{-1}$ of proton-proton collisions at $\sqrt{s} = 13$ TeV collected with the ATLAS detector at the LHC during 2015-2018 is used in the search. The observed transverse mass distribution computed from the lepton and missing transverse momenta is consistent with the distribution expected from the Standard Model, and upper limits on the cross section for $pp \to W^\prime \to \ell\nu$ are extracted ($\ell = e$ or $\mu$). These vary between 1.3 pb and 0.05 fb depending on the resonance mass in the range between 0.15 and 7.0 TeV at 95% confidence level for the electron and muon channels combined. Gauge bosons with a mass below 6.0 TeV and 5.1 TeV are excluded in the electron and muon channels, respectively, in a model with a resonance that has couplings to fermions identical to those of the Standard Model $W$ boson. Cross-section limits are also provided for resonances with several fixed $\Gamma / m$ values in the range between 1% and 15%. Model-independent limits are derived in single-bin signal regions defined by a varying minimum transverse mass threshold. The resulting visible cross-section upper limits range between 4.6 (15) pb and 22 (22) ab as the threshold increases from 130 (110) GeV to 5.1 (5.1) TeV in the electron (muon) channel.

14 data tables

Transverse mass distribution for events satisfying all selection criteria in the electron channel.

Transverse mass distribution for events satisfying all selection criteria in the muon channel.

Upper limits at the 95% CL on the cross section for SSM $W^\prime$ production and decay to the electron+neutrino channel as a function of the $W^\prime$ pole mass.

More…

Measurement of fiducial and differential $W^+W^-$ production cross-sections at $\sqrt{s}=$13 TeV with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
No Journal Information, 2019.
Inspire Record 1734263 DOI 10.17182/hepdata.89225

A measurement of fiducial and differential cross-sections for $W^+W^-$ production in proton-proton collisions at $\sqrt{s}=$13 TeV with the ATLAS experiment at the Large Hadron Collider using data corresponding to an integrated luminosity of $36.1$ fb$^{-1}$ is presented. Events with one electron and one muon are selected, corresponding to the decay of the diboson system as $WW\rightarrow e^{\pm}\nu\mu^{\mp}\nu$. To suppress top-quark background, events containing jets with a transverse momentum exceeding 35 GeV are not included in the measurement phase space. The fiducial cross-section, six differential distributions and the cross-section as a function of the jet-veto transverse momentum threshold are measured and compared with several theoretical predictions. Constraints on anomalous electroweak gauge boson self-interactions are also presented in the framework of a dimension-six effective field theory.

43 data tables

Measured fiducial cross-section as a function of the jet-veto $p_{T}$ threshold. The value at the jet-veto $p_{T}$ threshold of 35GeV corresponds to the nominal fiducial cross section measured in this publication.

Statistical correlation between bins in data for the measured fiducial cross-section as a function of the jet-veto $p_{T}$ threshold. The value at the jet-veto $p_{T}$ threshold of 35GeV corresponds to the nominal fiducial cross section measured in this publication.

Total correlation between bins in data for the measured fiducial cross-section as a function of the jet-veto $p_{T}$ threshold. The value at the jet-veto $p_{T}$ threshold of 35GeV corresponds to the nominal fiducial cross section measured in this publication.

More…

Measurement of the $t\bar{t}Z$ and $t\bar{t}W$ cross sections in proton-proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Rev. D99 (2019) 072009, 2019.
Inspire Record 1713423 DOI 10.17182/hepdata.88175

A measurement of the associated production of a top-quark pair (tt¯) with a vector boson (W, Z) in proton-proton collisions at a center-of-mass energy of 13 TeV is presented, using 36.1  fb-1 of integrated luminosity collected by the ATLAS detector at the Large Hadron Collider. Events are selected in channels with two same- or opposite-sign leptons (electrons or muons), three leptons or four leptons, and each channel is further divided into multiple regions to maximize the sensitivity of the measurement. The tt¯Z and tt¯W production cross sections are simultaneously measured using a combined fit to all regions. The best-fit values of the production cross sections are σtt¯Z=0.95±0.08stat±0.10syst  pb and σtt¯W=0.87±0.13stat±0.14syst  pb in agreement with the Standard Model predictions. The measurement of the tt¯Z cross section is used to set constraints on effective field theory operators which modify the tt¯Z vertex.

5 data tables

The result of the simultaneous fit to the $t\bar{t}Z$ and $t\bar{t}W$ cross sections.

68% confidence level (CL) contours of the measured $t\bar{t}Z$ and $t\bar{t}W$ cross sections.

95% confidence level (CL) contours of the measured $t\bar{t}Z$ and $t\bar{t}W$ cross sections.

More…

Measurement of electroweak WZ boson production and search for new physics in WZ $+$ two jets events in pp collisions at $\sqrt{s} =$ 13 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
No Journal Information, 2019.
Inspire Record 1713565 DOI 10.17182/hepdata.89174

A measurement of WZ electroweak (EW) vector boson scattering is presented. The measurement is performed in the leptonic decay modes WZ$\to \ell\nu\ell'\ell'$, where $\ell, \ell' = $e, $\mu$. The analysis is based on a data sample of proton-proton collisions at $\sqrt{s} =$ 13 TeV at the LHC collected with the CMS detector and corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The WZ plus two jet production cross section is measured in fiducial regions with enhanced contributions from EW production and found to be consistent with standard model predictions. The EW WZ production in association with two jets is measured with an observed (expected) significance of 2.2 (2.5) standard deviations. Constraints on charged Higgs boson production and on anomalous quartic gauge couplings in terms of dimension-eight effective field theory operators are also presented.

5 data tables

The measured WZ cross section in the tight EWK fiducial region.

The measured WZ cross section in the loose EWK fiducial region.

The measured EWK WZ scale factor (mu) in the tight EWK fiducial region. The uncertainty is the combined stastical uncertianty and the systematic uncertainty including experimental and theortical sources

More…

Search for the production of W$^\pm$W$^\pm$W$^\mp$ events at $\sqrt{s} =$ 13 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
No Journal Information, 2019.
Inspire Record 1734235 DOI 10.17182/hepdata.89176

A search for the production of events containing three W bosons predicted by the standard model is reported. The search is based on a data sample of proton-proton collisions at a center-of-mass energy of 13 TeV recorded by the CMS experiment at the CERN LHC and corresponding to a total integrated luminosity of 35.9 fb$^{-1}$. The search is performed in final states with three leptons (electrons or muons), or with two same-charge leptons plus two jets. The observed (expected) significance of the signal for W$^\pm$W$^\pm$W$^\mp$ production is 0.60 (1.78) standard deviations, and the ratio of the measured signal yield to that expected from the standard model is 0.34$^{+0.62}_{-0.34}$. Limits are placed on three anomalous quartic gauge couplings and on the production of massive axion-like particles.

9 data tables

Lost-lepton and three-lepton background contributions.

Non-prompt lepton background estimates.

Summary of typical systematic uncertainties of estimated background contributions.

More…

Observation of electroweak $W^{\pm}Z$ boson pair production in association with two jets in $pp$ collisions at $\sqrt{s} =$ 13 TeV with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Lett. B793 (2019) 469-492, 2019.
Inspire Record 1711223 DOI 10.17182/hepdata.83785

An observation of electroweak W±Z production in association with two jets in proton–proton collisions is presented. The data collected by the ATLAS detector at the Large Hadron Collider in 2015 and 2016 at a centre-of-mass energy of s=13 TeV are used, corresponding to an integrated luminosity of 36.1fb−1 . Events containing three identified leptons, either electrons or muons, and two jets are selected. The electroweak production of W±Z bosons in association with two jets is measured with an observed significance of 5.3 standard deviations. A fiducial cross-section for electroweak production including interference effects and for a single leptonic decay mode is measured to be σWZjj−EW=0.57−0.13+0.14(stat.)−0.06+0.07(syst.)fb . Total and differential fiducial cross-sections of the sum of W±Zjj electroweak and strong productions for several kinematic observables are also measured.

21 data tables

Fiducial cross section of the electroweak $W^{\pm}Z$ boson pair production in association with two jets. The first systematic uncertainty is experimental, the second is the theory modelling and interference systematics and the third one is the luminosity uncertainty.

Fiducial cross section of the $W^{\pm}Z$ boson pair production in association with two jets. The first systematic uncertainty is experimental, the second is the theory modelling and interference systematics and the third one is the luminosity uncertainty.

Numbers of observed and expected events in the $W^{\pm}Zjj$ signal region and in the three control regions, before the fit. The expected number of $WZjj-EW$ events from $SHERPA$ and the estimated number of background events from the other processes are shown. The sum of the background containing misidentified leptons is labelled "Misid. leptons". The total uncertainties are quoted.

More…