This paper presents studies of Bose-Einstein correlations (BEC) in proton-proton collisions at a centre-of-mass energy of 13 TeV, using data from the ATLAS detector at the CERN Large Hadron Collider. Data were collected in a special low-luminosity configuration with a minimum-bias trigger and a high-multiplicity track trigger, accumulating integrated luminosities of 151 $\mu$b$^{-1}$ and 8.4 nb$^{-1}$ respectively. The BEC are measured for pairs of like-sign charged particles, each with $|\eta|$ < 2.5, for two kinematic ranges: the first with particle $p_T$ > 100 MeV and the second with particle $p_T$ > 500 MeV. The BEC parameters, characterizing the source radius and particle correlation strength, are investigated as functions of charged-particle multiplicity (up to 300) and average transverse momentum of the pair (up to 1.5 GeV). The double-differential dependence on charged-particle multiplicity and average transverse momentum of the pair is also studied. The BEC radius is found to be independent of the charged-particle multiplicity for high charged-particle multiplicity (above 100), confirming a previous observation at lower energy. This saturation occurs independent of the transverse momentum of the pair.
Comparison of single-ratio two-particle correlation functions, C<sub>2</sub><sup>data</sup>(Q) and C<sub>2</sub><sup>MC</sup>(Q), with the two-particle double-ratio correlation function, R<sub>2</sub>(Q), for the high-multiplicity track (HMT) events using the opposite hemisphere (OHP) like-charge particles pairs reference sample for k<sub>T</sub> - interval 1000 < k<sub>T</sub> ≤ 1500 MeV.
Comparison of single-ratio two-particle correlation functions, C<sub>2</sub><sup>data</sup>(Q) and C<sub>2</sub><sup>MC</sup>(Q), with the two-particle double-ratio correlation function, R<sub>2</sub>(Q), for the high-multiplicity track (HMT) events using the unlike-charge particle (UCP) pairs reference sample for k<sub>T</sub> - interval 1000 < k<sub>T</sub> ≤ 1500 MeV.
The Bose-Einstein correlation (BEC) parameter R as a function of n<sub>ch</sub> for MB events using different MC generators in the calculation of R<sub>2</sub>(Q). The uncertainties shown are statistical. The lower panel of each plot shows the ratio of the BEC parameters obtained using EPOS LHC (red circles), Pythia 8 Monash (blue squares) and Herwig++ UE-EE-5 (green triangles) compared with the parameters obtained using Pythia 8 A2. The gray band in the lower panels is the MC systematic uncertainty, obtained as explained in the text.
A search for resonances decaying into a W boson and a radion, where the radion decays into two W bosons, is presented. The data analyzed correspond to an integrated luminosity of 138 fb$^{-1}$ recorded in proton-proton collisions with the CMS detector at $\sqrt{s} =$ 13 TeV. One isolated charged lepton is required, together with missing transverse momentum and one or two massive large-radius jets, containing the decay products of either two or one W bosons, respectively. No excess over the background estimation is observed. The results are combined with those from a complementary channel with an all-hadronic final state, described in an accompanying paper. Limits are set on parameters of an extended warped extra-dimensional model. These searches are the first of their kind at the LHC.
Post-fit distributions of the reconstructed $\ell\nu$+jets system ($m_{\mathrm{j}\ell\nu}$, $m_{\mathrm{jj}\ell\nu}$) in data and simulation for SR4.
Observed upper limits at 95\% \CL on the signal cross section $\times$ branching fraction as functions of the $m_{\mathrm{W}_{\mathrm{KK}}}$ and $m_{\mathrm{R}}$ resonance masses after combinign with an analysis of the all-hadronic final state.
Expected median lower limit contour on the $m_{\mathrm{W}_{\mathrm{KK}}}$ and $m_{\mathrm{R}}$ plane after combinign with an analysis of the all-hadronic final state.
Measurements of the production cross-sections of the Standard Model (SM) Higgs boson ($H$) decaying into a pair of $\tau$-leptons are presented. The measurements use data collected with the ATLAS detector from $pp$ collisions produced at the Large Hadron Collider at a centre-of-mass energy of $\sqrt{s}=13\,\text{TeV}$, corresponding to an integrated luminosity of $139\,\text{fb}^{-1}$. Leptonic ($\tau\to\ell\nu_{\ell}\nu_{\tau}$) and hadronic ($\tau\to\text{hadrons}~\nu_{\tau}$) decays of the $\tau$-lepton are considered. All measurements account for the branching ratio of $H\to\tau\tau$ and are performed with a requirement $|y_H|<2.5$, where $y_H$ is the true Higgs boson rapidity. The cross-section of the $pp\to H\to\tau\tau$ process is measured to be $2.94 \pm 0.21 \text{(stat)} ^{+\,0.37}_{-\,0.32} \text{(syst)}$ pb, in agreement with the SM prediction of $3.17\pm0.09~ \mbox{pb}$. Inclusive cross-sections are determined separately for the four dominant production modes: $2.65 \pm 0.41 \text{(stat)} ^{+\,0.91}_{-\,0.67} \text{(syst)}$ pb for gluon$-$gluon fusion, $0.197 \pm 0.028 \text{(stat)} ^{+\,0.032}_{-\,0.026} \text{(syst)}$ pb for vector-boson fusion, $0.115 \pm 0.058 \text{(stat)} ^{+\,0.042}_{-\,0.040} \text{(syst)}$ pb for vector-boson associated production, and $0.033 \pm 0.031 \text{(stat)} ^{+\,0.022}_{-\,0.017} \text{(syst)}$ pb for top-quark pair associated production. Measurements in exclusive regions of the phase space, using the simplified template cross-section framework, are also performed. All results are in agreement with the SM predictions.
Observed yields in the boost_0_1J signal region category of the hh channel.
Observed yields in the boost_0_ge2J signal region category of the hh channel.
Observed yields in the boost_1_1J signal region category of the hh channel.
The production cross section of a top quark pair in association with a photon is measured in proton-proton collisions in the decay channel with two oppositely charged leptons (e$^\pm\mu^\mp$, e$^+$e$^-$, or $\mu^+\mu^-$). The measurement is performed using 138 fb$^{-1}$ of proton-proton collision data recorded by the CMS experiment at $\sqrt{s} =$ 13 TeV during the 2016-2018 data-taking period of the CERN LHC. A fiducial phase space is defined such that photons radiated by initial-state particles, top quarks, or any of their decay products are included. An inclusive cross section of 175.2 $\pm$ 2.5 (stat) $\pm$ 6.3 (syst) fb is measured in a signal region with at least one jet coming from the hadronization of a bottom quark and exactly one photon with transverse momentum above 20 GeV. Differential cross sections are measured as functions of several kinematic observables of the photon, leptons, and jets, and compared to standard model predictions. The measurements are also interpreted in the standard model effective field theory framework, and limits are found on the relevant Wilson coefficients from these results alone and in combination with a previous CMS measurement of the $\mathrm{t\bar{t}}\gamma$ production process using the lepton+jets final state.
Observed and predicted event yields as a function of $p_{T}(\gamma)$ in the $e\mu$ channel, after the fit to the data.
Observed and predicted event yields as a function of $p_{T}(\gamma)$ in the $ee$ channel, after the fit to the data.
Observed and predicted event yields as a function of $p_{T}(\gamma)$ in the $\mu\mu$ channel, after the fit to the data.
A search for Kaluza-Klein excited vector boson resonances, $W_\mathrm{KK}$, decaying in cascade to three W bosons via a scalar radion $R, W_\mathrm{KK}\to WR \to WWW$, with two or three massive jets is presented. The search is performed with proton-proton collision data recorded at $\sqrt{s} =$ 13 TeV, collected by the CMS experiment at the CERN LHC, during 2016-2018, corresponding to an integrated luminosity of 138 fb$^{-1}$. Two final states are simultaneously probed, one where the two W bosons produced by the R decay are reconstructed as separate, large-radius, massive jets, and one where they are merged in a single large-radius jet. The observed data are in agreement with the standard model expectations. Limits are set on the product of the $W_\mathrm{KK}$ resonance cross section and branching fraction to three W bosons in an extended warped extra-dimensional model and are the first of their kind at the LHC.
Distribution of $m_{\mathrm{jj}}$ for preselected events with $\mathrm{N}_{j}$ = 2
Distribution of $m_{\mathrm{j}}$ for preselected events with $\mathrm{N}_{j}$ = 2
Distribution of the deep-WH value of the highest-mass jet with $m_{\mathrm{j}}$ > 100 GeV for preselected events with $\mathrm{N}_{j}$ = 2
This search, a type not previously performed at ATLAS, uses a comparison of the production cross sections for $e^+ \mu^-$ and $e^- \mu^+$ pairs to constrain physics processes beyond the Standard Model. It uses $139 \text{fb}^{-1}$ of proton$-$proton collision data recorded at $\sqrt{s} = 13$ TeV at the LHC. Targeting sources of new physics which prefer final states containing $e^{+}\mu^{-}$ to $e^{-}\mu^{+}$, the search contains two broad signal regions which are used to provide model-independent constraints on the ratio of cross sections at the 2% level. The search also has two special selections targeting supersymmetric models and leptoquark signatures. Observations using one of these selections are able to exclude, at 95% confidence level, singly produced smuons with masses up to 640 GeV in a model in which the only other light sparticle is a neutralino when the $R$-parity-violating coupling $\lambda'_{231}$ is close to unity. Observations using the other selection exclude scalar leptoquarks with masses below 1880 GeV when $g_{\text{1R}}^{eu}=g_{\text{1R}}^{\mu c}=1$, at 95% confidence level. The limit on the coupling reduces to $g_{\text{1R}}^{eu}=g_{\text{1R}}^{\mu c}=0.46$ for a mass of 1420 GeV.
Observed yields, and (post-fit) expected yields for the data-driven SM estimates. Yields are shown for the benchmark RPV-supersymmetry signal points in SR-RPV and the leptoquark signal points in SR-LQ after a fit excluding the $e^{+}\mu^{-}$ signal region and setting $\mu_{\text{sig}}=1$. Small weights correcting for muon charge biases affect all rows except that containing the fake-lepton estimate. These weights, $w_i$, cause non-integer yields. The uncertainties, $\sqrt{\sum_i w_i^2}$, are given for data to support the choice made to model the yields with a Poisson distribution.
The observed exclusion contour at 95% CL as a function of the smuon and neutralino masses, for $\lambda_{231}^{'}=1.0$.
The expected exclusion contour at 95% CL as a function of the smuon and neutralino masses, for $\lambda_{231}^{'}=1.0$.
Inclusive and differential cross sections of single top quark production in association with a Z boson are measured in proton-proton collisions at a center-of-mass energy of 13 TeV with a data sample corresponding to an integrated luminosity of 138 fb$^{-1}$ recorded by the CMS experiment. Events are selected based on the presence of three leptons, electrons or muons, associated with leptonic Z boson and top quark decays. The measurement yields an inclusive cross section of 87.9 $_{-7.3}^{+7.5}$ (stat) $_{-6.0}^{+7.3}$ (syst) fb for a dilepton invariant mass greater than 30 GeV, in agreement with standard model (SM) calculations and the most precise determination to date. The ratio between the cross sections for the top quark and the top antiquark production in association with a Z boson is measured as 2.37 $_{-0.42}^{+0.56}$ (stat) ${}_{-0.13}^{+0.27}$ (syst). Differential measurements at parton and particle levels are performed for the first time. Several kinematic observables are considered to study the modeling of the process. Results are compared to theoretical predictions with different assumptions on the source of the initial-state b quark and found to be in agreement, within the uncertainties. Additionally, the spin asymmetry, which is sensitive to the top quark polarization, is determined from the differential distribution of the polarization angle at parton level to be 0.54 $\pm$ 0.16 (stat) $\pm$ 0.06 (syst), in agreement with SM predictions.
Numerical results of inclusive cross section measurements. Each row represents a measurement: "tZq" for fully inclusive, "tZq_top" for the top quark channel, "tZq_antitop" for the top antiquark channel, "ratio" for the ratio measurement. The columns are the central value, statistical error up/down, systematic error up/down. All values are in fb, except for the ratio (dimensionless).
Numerical representation of impact plot.
Simulated signal, total background, and observed data in the signal category with exactly 1 b jet and 2-3 jets for the three data-taking years combined. For the uncertainty on the signal and background, both the total (systematic+statistical) and statistical uncertainties are provided. The uncertainty on the data is the (statistical) Poisson uncertainty. Note that this is the prefit version.
A measurement of the cross section of the associated production of a single top quark and a W boson in final states with a muon or electron and jets in proton-proton collisions at $\sqrt{s}$ = 13 TeV is presented. The data correspond to an integrated luminosity of 36 fb$^{-1}$ collected with the CMS detector at the CERN LHC in 2016. A boosted decision tree is used to separate the tW signal from the dominant $\mathrm{t\bar{t}}$ background, whilst the subleading W+jets and multijet backgrounds are constrained using data-based estimates. This result is the first observation of the tW process in final states containing a muon or electron and jets, with a significance exceeding 5 standard deviations. The cross section is determined to be 89 $\pm$ 4 (stat) $\pm$ 12 (syst) pb, consistent with the standard model.
The observed and theoretical cross section. In the observed, the first uncertainty is statistical, the second uncertianty is the systematic. In the expected, the first uncertainty is due to scale variations, the second due to the choice of PDF.
The systematic sources considered in the analysis and their relative contribution to the observed uncertainty. The uncertainties are divided by normalization, experimental, theoretical and statistical uncertainties, with each section ordered by their contribution to the total uncertainty.
The production of dark matter in association with Higgs bosons is predicted in several extensions of the Standard Model. An exploration of such scenarios is presented, considering final states with missing transverse momentum and $b$-tagged jets consistent with a Higgs boson. The analysis uses proton-proton collision data at a centre-of-mass energy of 13 TeV recorded by the ATLAS experiment at the LHC during Run 2, amounting to an integrated luminosity of 139 fb$^{-1}$. The analysis, when compared with previous searches, benefits from a larger dataset, but also has further improvements providing sensitivity to a wider spectrum of signal scenarios. These improvements include both an optimised event selection and advances in the object identification, such as the use of the likelihood-based significance of the missing transverse momentum and variable-radius track-jets. No significant deviation from Standard Model expectations is observed. Limits are set, at 95% confidence level, in two benchmark models with two Higgs doublets extended by either a heavy vector boson $Z'$ or a pseudoscalar singlet $a$ and which both provide a dark matter candidate $\chi$. In the case of the two-Higgs-doublet model with an additional vector boson $Z'$, the observed limits extend up to a $Z'$ mass of 3 TeV for a mass of 100 GeV for the dark matter candidate. The two-Higgs-doublet model with a dark matter particle mass of 10 GeV and an additional pseudoscalar $a$ is excluded for masses of the $a$ up to 520 GeV and 240 GeV for $\tan \beta = 1$ and $\tan \beta = 10$ respectively. Limits on the visible cross-sections are set and range from 0.05 fb to 3.26 fb, depending on the missing transverse momentum and $b$-quark jet multiplicity requirements.
<b>- - - - - - - - Overview of HEPData Record - - - - - - - -</b> <br><br> <b>Exclusion contours:</b> <ul> <li><a href="?table=LimitContour_ZP2HDM_obs">Observed 95% CL exclusion limit for the Z'-2HDM model</a> <li><a href="?table=LimitContour_ZP2HDM_exp">Expected 95% CL exclusion limit for the Z'-2HDM model</a> <li><a href="?table=LimitContour_ZP2HDM_exp_1s">Expected +- 1sigma 95% CL exclusion limit for the Z'-2HDM model</a> <li><a href="?table=LimitContour_ZP2HDM_exp_2s">Expected +- 2sigma 95% CL exclusion limit for the Z'-2HDM model</a> <li><a href="?table=LimitContour_2HDMa_tb1_sp0p35_obs">Observed 95% CL exclusion limit for ggF production in the 2HDM+a model</a> <li><a href="?table=LimitContour_2HDMa_tb1_sp0p35_exp">Expected 95% CL exclusion limit for ggF production in the 2HDM+a model</a> <li><a href="?table=LimitContour_2HDMa_tb1_sp0p35_exp_1s">Expected +- 1 sigma 95% CL exclusion limit for ggF production in the 2HDM+a model</a> <li><a href="?table=LimitContour_2HDMa_tb1_sp0p35_exp_2s">Expected +- 2 sigma 95% CL exclusion limit for ggF production in the 2HDM+a model</a> <li><a href="?table=LimitContour_2HDMa_tb10_sp0p35_obs">Observed 95% CL exclusion limit for bbA production in the 2HDM+a model</a> <li><a href="?table=LimitContour_2HDMa_tb10_sp0p35_exp">Expected 95% CL exclusion limit for bbA production in the 2HDM+a model</a> <li><a href="?table=LimitContour_2HDMa_tb10_sp0p35_exp_1s">Expected +- 1 sigma 95% CL exclusion limit for bbA production in the 2HDM+a model</a> <li><a href="?table=LimitContour_2HDMa_tb10_sp0p35_exp_2s">Expected +- 2 sigma 95% CL exclusion limit for bbA production in the 2HDM+a model</a> <li><a href="?table=LimitContour_ZP2HDM_2018CONF_obs">Observed 95% CL exclusion limit for the Z'-2HDM model with the benchmark used in arXiv:1707.01302.</a> <li><a href="?table=LimitContour_ZP2HDM_2018CONF_exp">Expected 95% CL exclusion limit for the Z'-2HDM model with the benchmark used in arXiv:1707.01302.</a> <li><a href="?table=LimitContour_ZP2HDM_2018CONF_exp_1s">Expected +- 1 sigma 95% CL exclusion limit for the Z'-2HDM model with the benchmark used in arXiv:1707.01302.</a> <li><a href="?table=LimitContour_ZP2HDM_2018CONF_exp_2s">Expected +- 2 sigma 95% CL exclusion limit for the Z'-2HDM model with the benchmark used in arXiv:1707.01302.</a> </ul> <b>Upper limits on cross-sections:</b> <ul> <li><a href="?table=Limits_ZP2HDM">95% CL upper limit on the cross-section for the Z'-2HDM model</a> <li><a href="?table=Limits_2HDMa_tb1_sp0p35">95% CL upper limit on the ggF cross-section in the 2HDM+a model</a> <li><a href="?table=Limits_2HDMa_tb10_sp0p35">95% CL upper limit on the bbA cross-section in the 2HDM+a model</a> <li><a href="?table=MIL">95% CL upper limit on the visible cross-section</a> </ul> <b>Theoretical cross-sections:</b> <ul> <li><a href="?table=CrossSections_ZP2HDM">Cross-section for the Z'-2HDM model</a> <li><a href="?table=CrossSections_2HDMa_tb1_sp0p35">Cross-section for ggF production in the 2HDM+a model</a> <li><a href="?table=CrossSections_2HDMa_tb10_sp0p35">Cross-section for bbA production in the 2HDM+a model</a> </ul> <b>Kinematic distributions:</b> <ul> <li><a href="?table=SR_post_plot_2b_150_200">Higgs candidate invariant mass in the region with 2 b-jets and missing energy between 150-200 GeV</a> <li><a href="?table=SR_post_plot_2b_200_350">Higgs candidate invariant mass in the region with 2 b-jets and missing energy between 200-350 GeV</a> <li><a href="?table=SR_post_plot_2b_350_500">Higgs candidate invariant mass in the region with 2 b-jets and missing energy between 350-500 GeV</a> <li><a href="?table=SR_post_plot_2b_500_750">Higgs candidate invariant mass in the region with 2 b-jets and missing energy between 500-750 GeV</a> <li><a href="?table=SR_post_plot_2b_750">Higgs candidate invariant mass in the region with 2 b-jets and missing energy higher than 750 GeV</a> <li><a href="?table=SR_post_plot_3b_150_200">Higgs candidate invariant mass in the region with at least 3 b-jets and missing energy between 150-200 GeV</a> <li><a href="?table=SR_post_plot_3b_200_350">Higgs candidate invariant mass in the region with at least 3 b-jets and missing energy between 200-350 GeV</a> <li><a href="?table=SR_post_plot_3b_350_500">Higgs candidate invariant mass in the region with at least 3 b-jets and missing energy between 350-500 GeV</a> <li><a href="?table=SR_post_plot_3b_500">Higgs candidate invariant mass in the region with at least 3 b-jets and missing energy higher than 500 GeV</a> <li><a href="?table=MET_post_plot_0L2b">Missing energy in events with 0 leptons and 2 b-jets</a> <li><a href="?table=MET_post_plot_0L3b">Missing energy in events with 0 leptons and at least 3 b-jets</a> <li><a href="?table=CR_post_plot_CR1">Yields in the different missing energy bins and muon-charge of the 1-lepton control region</a> <li><a href="?table=CR_post_plot_CR2">Yields in the different METlepInv bins of the 2-lepton control region</a> </ul> <b>Cut flows:</b> The tables contain three columns, corresponding to the Z'-2HDM and 2HDM+a model assuming 100% ggF or bbA production respectively. <ul> <li><a href="?table=Resolved_150_200_2b">Signal region with 2 b-jets and missing energy between 150-200 GeV</a> <li><a href="?table=Resolved_200_350_2b">Signal region with 2 b-jets and missing energy between 200-350 GeV</a> <li><a href="?table=Resolved_350_500_2b">Signal region with 2 b-jets and missing energy between 350-500 GeV</a> <li><a href="?table=Merged_500_750_2w0b">Signal region with 2 b-jets and missing energy between 500-750 GeV</a> <li><a href="?table=Merged_750_2w0b">Signal region with 2 b-jets and missing energy higher than 750 GeV</a> <li><a href="?table=Resolved_150_200_3pb">Signal region with at least 3 b-jets and missing energy between 150-200 GeV</a> <li><a href="?table=Resolved_200_350_3pb">Signal region with at least 3 b-jets and missing energy between 200-350 GeV</a> <li><a href="?table=Resolved_350_500_3pb">Signal region with at least 3 b-jets and missing energy between 350-500 GeV</a> <li><a href="?table=Merged_2w1pb">Signal region with at least 3 b-jets and missing energy higher than 500 GeV</a> </ul> <b>Acceptance and efficiencies:</b> <ul> <li><a href="?table=AcceptanceTimesEfficiency_a2HDM_bb_2_150_noHiggsWindowCut">2HDM+a model, bbA production, 2 b-jets, MET=150-200 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_a2HDM_bb_2_200_noHiggsWindowCut">2HDM+a model, bbA production, 2 b-jets, MET=200-350 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_a2HDM_bb_2_350_noHiggsWindowCut">2HDM+a model, bbA production, 2 b-jets, MET=350-500 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_a2HDM_bb_2_500_noHiggsWindowCut">2HDM+a model, bbA production, 2 b-jets, MET=500-750 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_a2HDM_bb_2_750ptv_noHiggsWindowCut">2HDM+a model, bbA production, 2 b-jets, MET higher than 750 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_a2HDM_bb_3_150_noHiggsWindowCut">2HDM+a model, bbA production, at least 3 b-jets, MET=150-200 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_a2HDM_bb_3_200_noHiggsWindowCut">2HDM+a model, bbA production, at least 3 b-jets, MET=200-350 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_a2HDM_bb_3_350_noHiggsWindowCut">2HDM+a model, bbA production, at least 3 b-jets, MET=350-500 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_a2HDM_bb_3_500ptv_noHiggsWindowCut">2HDM+a model, bbA production, at least 3 b-jets, MET higher than GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_a2HDM_ggF_2_150_noHiggsWindowCut">2HDM+a model, ggF production, 2 b-jets, MET=150-200 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_a2HDM_ggF_2_200_noHiggsWindowCut">2HDM+a model, ggF production, 2 b-jets, MET=200-350 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_a2HDM_ggF_2_350_noHiggsWindowCut">2HDM+a model, ggF production, 2 b-jets, MET=350-500 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_a2HDM_ggF_2_500_noHiggsWindowCut">2HDM+a model, ggF production, 2 b-jets, MET=500-750 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_a2HDM_ggF_2_750ptv_noHiggsWindowCut">2HDM+a model, ggF production, 2 b-jets, MET higher than 750 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_a2HDM_ggF_3_150_noHiggsWindowCut">2HDM+a model, ggF production, at least 3 b-jets, MET=150-200 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_a2HDM_ggF_3_200_noHiggsWindowCut">2HDM+a model, ggF production, at least 3 b-jets, MET=200-350 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_a2HDM_ggF_3_350_noHiggsWindowCut">2HDM+a model, ggF production, at least 3 b-jets, MET=350-500 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_a2HDM_ggF_3_500ptv_noHiggsWindowCut">2HDM+a model, ggF production, at least 3 b-jets, MET higher than 500 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_zp2hdm_CMS_2_150_noHiggsWindowCut">Z'-2HDM model, 2 b-jets, MET=150-200 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_zp2hdm_CMS_2_200_noHiggsWindowCut">Z'-2HDM model, 2 b-jets, MET=200-350 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_zp2hdm_CMS_2_350_noHiggsWindowCut">Z'-2HDM model, 2 b-jets, MET=350-500 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_zp2hdm_CMS_2_500_noHiggsWindowCut">Z'-2HDM model, 2 b-jets, MET=500-750 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_zp2hdm_CMS_2_750ptv_noHiggsWindowCut">Z'-2HDM model, 2 b-jets, MET higher than 750 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_zp2hdm_CMS_3_150_noHiggsWindowCut">Z'-2HDM model, at least 3 b-jets, MET=150-200 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_zp2hdm_CMS_3_200_noHiggsWindowCut">Z'-2HDM model, at least 3 b-jets, MET=200-350 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_zp2hdm_CMS_3_350_noHiggsWindowCut">Z'-2HDM model, at least 3 b-jets, MET=350-500 GeV</a> <li><a href="?table=AcceptanceTimesEfficiency_zp2hdm_CMS_3_500ptv_noHiggsWindowCut">Z'-2HDM model, at least 3 b-jets, MET higher than 500 GeV</a> </ul>
Observed 95% CL exclusion limit for the Zprime-2HDM model.
Expected 95% CL exclusion limit for the Zprime-2HDM model.
A search optimized for new heavy particles decaying to two $b$-quarks and produced in association with additional $b$-quarks is reported. The sensitivity is improved by $b$-tagging at least one lower-$p_{\rm{T}}$ jet in addition to the two highest-$p_{\rm{T}}$ jets. The data used in this search correspond to an integrated luminosity of 103 $\text{fb}^{-1}$ collected with a dedicated trijet trigger during the 2017 and 2018 $\sqrt{s} = 13$ TeV proton-proton collision runs with the ATLAS detector at the LHC. The search looks for resonant peaks in the $b$-tagged dijet invariant mass spectrum over a smoothly falling background. The background is estimated with an innovative data-driven method based on orthonormal functions. The observed $b$-tagged dijet invariant mass spectrum is compatible with the background-only hypothesis. Upper limits at 95% confidence level on a heavy vector-boson production cross section times branching ratio to a pair of $b$-quarks are derived.
Background estimate from the FD method with N=3 and data in the SR.
The observed (solid) and expected (dashed) 95% CL upper limits on the production of $Z' \to b\bar{b}$ in association with b-quarks.
Acceptance and Acceptance times efficiency for the LUV Z' model.