A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and missing transverse momentum are considered. The analysis uses 36.1 $fb^{-1}$ of proton-proton collision data recorded by the ATLAS experiment at $\sqrt{s}$ = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are interpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour-neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross-section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour-charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements.
- - - - - - - - Overview of HEPData Record - - - - - - - - <br/><br/> <b>Systematic uncertainties:</b> <a href="80080?version=1&table=Table2">table</a><br/><br/> <b>Fit results:</b> <a href="80080?version=1&table=Table3">SRb1 and SRb2</a> <a href="80080?version=1&table=Table4">SRt1, SRt2 and SRt3</a><br/><br/> <b>Upper limits:</b> <a href="80080?version=1&table=Table5">table</a><br/><br/> <b>SR distributions:</b> <ul> <li><a href="80080?version=1&table=Table6">SRb1: $E_{\mathrm T}^{\mathrm{miss}}$</a> <li><a href="80080?version=1&table=Table7">SRb2: $\cos{\theta}^*_{bb}$</a> <li><a href="80080?version=1&table=Table8">SRt1: $m_{\mathrm T}^{\mathrm{b,min}}$</a> <li><a href="80080?version=1&table=Table9">SRt2: $E_{\mathrm T}^{\mathrm{miss,sig}}$</a> <li><a href="80080?version=1&table=Table10">SRt3: $\xi^{+}_{\ell\ell}$</a> <li><a href="80080?version=1&table=Table34">SRb1: jet $p_{T}$</a> <li><a href="80080?version=1&table=Table35">SRb2: $H_{\mathrm T}^{ratio}$</a> <li><a href="80080?version=1&table=Table36">SRt1: $\Delta R_{bb}$</a> <li><a href="80080?version=1&table=Table37">SRt2: $M_{\mathrm T}^{b,min}$</a> <li><a href="80080?version=1&table=Table38">SRt3: $\Delta \phi_{boost}$</a> </ul> <b>Exclusion limits:</b> <ul> <li>Scalar SRb2 <a href="80080?version=1&table=Table11">expected</a> <a href="80080?version=1&table=Table12">observed</a> <li>Scalar SRt1/SRt2 <a href="80080?version=1&table=Table13">expected</a> <a href="80080?version=1&table=Table14">observed</a> <li>Scalar SRt3 <a href="80080?version=1&table=Table15">expected</a> <a href="80080?version=1&table=Table16">observed</a> <li>Pseudo-scalar SRb2 <a href="80080?version=1&table=Table17">expected</a> <a href="80080?version=1&table=Table18">observed</a> <li>Pseudo-scalar SRt1/SRt2 <a href="80080?version=1&table=Table19">expected</a> <a href="80080?version=1&table=Table20">observed</a> <li>Pseudo-scalar SRt3 <a href="80080?version=1&table=Table21">expected</a> <a href="80080?version=1&table=Table22">observed</a> <li>Scalar, SRt1/SRt2 vs DM mass <a href="80080?version=1&table=Table23">expected</a> <a href="80080?version=1&table=Table24">observed</a> <li>Scalar, SRt3 vs DM mass <a href="80080?version=1&table=Table25">expected</a> <a href="80080?version=1&table=Table26">observed</a> <li>Pseudo-scalar, SRt1/SRt2 vs DM mass <a href="80080?version=1&table=Table27">expected</a> <a href="80080?version=1&table=Table28">observed</a> <li>Pseudo-scalar, SRt3 vs DM mass <a href="80080?version=1&table=Table29">expected</a> <a href="80080?version=1&table=Table30">observed</a> <li>Colour-charged scalar mediators ($b-$FDM) <a href="80080?version=1&table=Table32">expected</a> <a href="80080?version=1&table=Table33">observed</a> </ul> <b>Direct detection plot:</b> <a href="80080?version=1&table=Table31">table</a><br/><br/> <b>Acceptances:</b> <ul> <li><a href="80080?version=1&table=Table39">SRb1</a> <li><a href="80080?version=1&table=Table41">SRb2 scalar</a> <li><a href="80080?version=1&table=Table44">SRb2 pseudo-scalar</a> <li><a href="80080?version=1&table=Table45">SRt2 scalar</a> <li><a href="80080?version=1&table=Table46">SRt1 scalar</a> <li><a href="80080?version=1&table=Table49">SRt2 pseudo-scalar</a> <li><a href="80080?version=1&table=Table50">SRt1 pseudo-scalar</a> <li><a href="80080?version=1&table=Table53">SRt3 scalar</a> <li><a href="80080?version=1&table=Table55">SRt3 pseudo-scalar</a> </ul> <b>Efficiencies:</b> <ul> <li><a href="80080?version=1&table=Table40">SRb1</a> <li><a href="80080?version=1&table=Table42">SRb2 scalar</a> <li><a href="80080?version=1&table=Table43">SRb2 pseudo-scalar</a> <li><a href="80080?version=1&table=Table47">SRt2 scalar</a> <li><a href="80080?version=1&table=Table48">SRt1 scalar</a> <li><a href="80080?version=1&table=Table51">SRt2 pseudo-scalar</a> <li><a href="80080?version=1&table=Table52">SRt1 pseudo-scalar</a> <li><a href="80080?version=1&table=Table54">SRt3 scalar</a> <li><a href="80080?version=1&table=Table56">SRt3 pseudo-scalar</a> </ul> <b>Cutflows:</b> <ul> <li><a href="80080?version=1&table=Table57">SRb1</a> <li><a href="80080?version=1&table=Table58">SRb2</a> <li><a href="80080?version=1&table=Table59">SRt1 scalar</a> <li><a href="80080?version=1&table=Table60">SRt2 scalar</a> <li><a href="80080?version=1&table=Table61">SRt1 pseudo-scalar</a> <li><a href="80080?version=1&table=Table62">SRt2 pseudo-scalar</a> <li><a href="80080?version=1&table=Table63">SRt3</a> </ul> <b>Truth Code snippets</b> are available under "Resources" (purple button on the left)
Summary of the main systematic uncertainties and their impact on the total SM background prediction in each of the signal regions studied. A range is shown for the four bins composing SRb2 . The total systematic uncertainty can be different from the sum in quadrature of individual sources due to the correlations between them resulting from the fit to the data. The quoted theoretical uncertainties include modelling and cross-section uncertainties.
Fit results in SRb1 and SRb2 for an integrated luminosity of $36.1 fb^{-1}$. The background normalisation parameters are obtained from the background-only fit in the CRs and are applied to the SRs. Small backgrounds are indicated as Others. The dominant component of these smaller background sources in SRb1 is di-boson processes. Benchmark signal models yields are given for each SR. The uncertainties on the yields include all systematic uncertainties.
This Letter presents the measurement of differential cross sections of isolated prompt photons produced in association with a b-jet or a c-jet. These final states provide sensitivity to the heavy-flavour content of the proton and aspects related to the modelling of heavy-flavour quarks in perturbative QCD. The measurement uses proton-proton collision data at a centre-of-mass energy of 8 TeV recorded by the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of up to 20.2 fb$^{-1}$. The differential cross sections are measured for each jet flavour with respect to the transverse energy of the leading photon in two photon pseudorapidity regions: $|\eta^\gamma|<1.37$ and $1.56<|\eta^\gamma|<2.37$. The measurement covers photon transverse energies $25 < E_\textrm{T}^\gamma<400$ GeV and $25 < E_\textrm{T}^\gamma<350$ GeV respectively for the two $|\eta^\gamma|$ regions. For each jet flavour, the ratio of the cross sections in the two $|\eta^\gamma|$ regions is also measured. The measurement is corrected for detector effects and compared to leading-order and next-to-leading-order perturbative QCD calculations, based on various treatments and assumptions about the heavy-flavour content of the proton. Overall, the predictions agree well with the measurement, but some deviations are observed at high photon transverse energies. The total uncertainty in the measurement ranges between 13% and 66%, while the central $\gamma+b$ measurement exhibits the smallest uncertainty, ranging from 13% to 27%, which is comparable to the precision of the theoretical predictions.
Measured fiducial integrated $\gamma+b$ and $\gamma+c$ cross sections for $|\eta^\gamma|<1.37$ and $1.56<|\eta^\gamma|<2.37$.
Measured $\gamma+b$ fiducial differential cross section as a function of $E_\text{T}^\gamma$ for $|\eta^\gamma|<1.37$.
Measured $\gamma+b$ fiducial differential cross section as a function of $E_\text{T}^\gamma$ for $1.56<|\eta^\gamma|<2.37$.
A search is conducted for new resonances decaying into a $WW$ or $WZ$ boson pair, where one $W$ boson decays leptonically and the other $W$ or $Z$ boson decays hadronically. It is based on proton-proton collision data with an integrated luminosity of 36.1 fb$^{-1}$ collected with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of $\sqrt{s}$ = 13 TeV in 2015 and 2016. The search is sensitive to diboson resonance production via vector-boson fusion as well as quark-antiquark annihilation and gluon-gluon fusion mechanisms. No significant excess of events is observed with respect to the Standard Model backgrounds. Several benchmark models are used to interpret the results. Limits on the production cross section are set for a new narrow scalar resonance, a new heavy vector-boson and a spin-2 Kaluza-Klein graviton.
Limit
Limit
A search for neutral heavy resonances is performed in the $WW\to e\nu\mu\nu$ decay channel using $pp$ collision data corresponding to an integrated luminosity of 36.1 fb$^{-1}$, collected at a centre-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. No evidence of such heavy resonances is found. In the search for production via the quark--antiquark annihilation or gluon--gluon fusion process, upper limits on $\sigma_X \times B(X \to WW)$ as a function of the resonance mass are obtained in the mass range between 200 GeV and up to 5 TeV for various benchmark models: a Higgs-like scalar in different width scenarios, a two-Higgs-doublet model, a heavy vector triplet model, and a warped extra dimensions model. In the vector-boson fusion process, constraints are also obtained on these resonances, as well as on a Higgs boson in the Georgi--Machacek model and a heavy tensor particle coupling only to gauge bosons.
Figure 1, left, subfigure a, Acceptance times efficiency as a function of signal mass for the ggF or qqA production. The "0" efficiency mass point means there's no such signal sample for the corresponding model.
Figure 1, right, subfigure b, Acceptance times efficiency as a function of signal mass for the VBF production. The "0" efficiency mass point means there's no such signal sample for the corresponding model.
Figure 2, left, subfigure a, Transverse mass distribution in the ggF top-quark control regions. For NWA signals, the "0" value means lack of statistics.
A search for heavy neutral Higgs bosons and $Z^{\prime}$ bosons is performed using a data sample corresponding to an integrated luminosity of 36.1 fb$^{-1}$ from proton-proton collisions at $\sqrt{s}$ = 13 TeV recorded by the ATLAS detector at the LHC during 2015 and 2016. The heavy resonance is assumed to decay to $\tau^+\tau^-$ with at least one tau lepton decaying to final states with hadrons and a neutrino. The search is performed in the mass range of 0.2-2.25 TeV for Higgs bosons and 0.2-4.0 TeV for $Z^{\prime}$ bosons. The data are in good agreement with the background predicted by the Standard Model. The results are interpreted in benchmark scenarios. In the context of the hMSSM scenario, the data exclude $\tan\beta > 1.0$ for $m_A$ = 0.25 TeV and $\tan\beta > 42$ for $m_A$ = 1.5 TeV at the 95% confidence level. For the Sequential Standard Model, $Z^{\prime}_\mathrm{SSM}$ with $m_{Z^{\prime}} < 2.42$ TeV is excluded at 95% confidence level, while $Z^{\prime}_\mathrm{NU}$ with $m_{Z^{\prime}} < 2.25$ TeV is excluded for the non-universal $G(221)$ model that exhibits enhanced couplings to third-generation fermions.
Observed and predicted mTtot distribution in the b-veto category of the 1l1tau_h channel. Despite listing this as an exclusive final state (as there must be no b-jets), there is no explicit selection on the presence of additional light-flavour jets. Please note that the bin content is divided by the bin width in the paper figure, but not in the HepData table. In the paper, the first bin is cut off at 60 GeV for aesthetics but contains underflows down to 50 GeV as in the HepData table. The last bin includes overflows. The combined prediction for A and H bosons with masses of 300, 500 and 800 GeV and $\tan\beta$ = 10 in the hMSSM scenario are also provided.
Observed and predicted mTtot distribution in the b-tag category of the 1l1tau_h channel. Despite listing this as an exclusive final state (as there must be at least one b-jets), there is no explicit selection on the presence of additional light-flavour jets. Please note that the bin content is divided by the bin width in the paper figure, but not in the HepData table. In the paper, the first bin is cut off at 60 GeV for aesthetics but contains underflows down to 50 GeV as in the HepData table. The last bin includes overflows. The combined prediction for A and H bosons with masses of 300, 500 and 800 GeV and $\tan\beta$ = 10 in the hMSSM scenario are also provided.
Observed and predicted mTtot distribution in the b-veto category of the 2tau_h channel. Despite listing this as an exclusive final state (as there must be no b-jets), there is no explicit selection on the presence of additional light-flavour jets. Please note that the bin content is divided by the bin width in the paper figure, but not in the HepData table. The last bin includes overflows. The combined prediction for A and H bosons with masses of 300, 500 and 800 GeV and $\tan\beta$ = 10 in the hMSSM scenario are also provided.
A search for heavy resonances decaying into a Higgs boson ($H$) and a new particle ($X$) is reported, utilizing 36.1 fb$^{-1}$ of proton-proton collision data at $\sqrt{s} =$ 13 TeV collected during 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. The particle $X$ is assumed to decay to a pair of light quarks, and the fully hadronic final state $XH \rightarrow q\bar q'b\bar b$ is analysed. The search considers the regime of high $XH$ resonance masses, where the $X$ and $H$ bosons are both highly Lorentz-boosted and are each reconstructed using a single jet with large radius parameter. A two-dimensional phase space of $XH$ mass versus $X$ mass is scanned for evidence of a signal, over a range of $XH$ resonance mass values between 1 TeV and 4 TeV, and for $X$ particles with masses from 50 GeV to 1000 GeV. All search results are consistent with the expectations for the background due to Standard Model processes, and 95% CL upper limits are set, as a function of $XH$ and $X$ masses, on the production cross-section of the $XH\rightarrow q\bar q'b\bar b$ resonance.
mass distribution
mass distribution
mass distribution
Combined ATLAS and CMS measurements of the Higgs boson production and decay rates, as well as constraints on its couplings to vector bosons and fermions, are presented. The combination is based on the analysis of five production processes, namely gluon fusion, vector boson fusion, and associated production with a $W$ or a $Z$ boson or a pair of top quarks, and of the six decay modes $H \to ZZ, WW$, $\gamma\gamma, \tau\tau, bb$, and $\mu\mu$. All results are reported assuming a value of 125.09 GeV for the Higgs boson mass, the result of the combined measurement by the ATLAS and CMS experiments. The analysis uses the CERN LHC proton--proton collision data recorded by the ATLAS and CMS experiments in 2011 and 2012, corresponding to integrated luminosities per experiment of approximately 5 fb$^{-1}$ at $\sqrt{s}=7$ TeV and 20 fb$^{-1}$ at $\sqrt{s} = 8$ TeV. The Higgs boson production and decay rates measured by the two experiments are combined within the context of three generic parameterisations: two based on cross sections and branching fractions, and one on ratios of coupling modifiers. Several interpretations of the measurements with more model-dependent parameterisations are also given. The combined signal yield relative to the Standard Model prediction is measured to be 1.09 $\pm$ 0.11. The combined measurements lead to observed significances for the vector boson fusion production process and for the $H \to \tau\tau$ decay of $5.4$ and $5.5$ standard deviations, respectively. The data are consistent with the Standard Model predictions for all parameterisations considered.
Best fit values of $\sigma_i \cdot \mathrm{B}^f$ for each specific channel $i \to H\to f$, as obtained from the generic parameterisation with 23 parameters for the combination of the ATLAS and CMS measurements, using the $\sqrt{s}$=7 and 8 TeV data. The cross sections are given for $\sqrt{s}$=8 TeV, assuming the SM values for $\sigma_i(7 \mathrm{TeV})/\sigma_i(8 \mathrm{TeV})$. The results are shown together with their total uncertainties and their breakdown into statistical and systematic components. The missing values are either not measured with a meaningful precision and therefore not quoted, in the case of the $H\to ZZ$ decay channel for the $WH$, $ZH$, and $ttH$ production processes, or not measured at all and therefore fixed to their corresponding SM predictions, in the case of the $H\to bb$ decay mode for the $gg\mathrm{F}$ and VBF production processes.
Best fit values of $\sigma_i \cdot \mathrm{B}^f$ relative to their SM prediction for each specific channel $i \to H\to f$, as obtained from the generic parameterisation with 23 parameters for the combination of the ATLAS and CMS measurements, using the $\sqrt{s}$=7 and 8 TeV data. The results are shown together with their total uncertainties and their breakdown into statistical and systematic components. The missing values are either not measured with a meaningful precision and therefore not quoted, in the case of the $H\to ZZ$ decay channel for the $WH$, $ZH$, and $ttH$ production processes, or not measured at all and therefore fixed to their corresponding SM predictions, in the case of the $H\to bb$ decay mode for the $gg\mathrm{F}$ and VBF production processes.
Best fit values of $\sigma(gg\to H\to ZZ)$, $\sigma_i/\sigma_{gg\mathrm{F}}$, and $\mathrm{B}^f/\mathrm{B}^{ZZ}$ from the combined analysis of the $\sqrt{s}$=7 and 8 TeV data. The values involving cross sections are given for $\sqrt{s}$=8 TeV, assuming the SM values for $\sigma_i(7 \mathrm{TeV})/\sigma_i(8 \mathrm{TeV})$. The results are shown for the combination of ATLAS and CMS, and also separately for each experiment, together with their total uncertainties and their breakdown into the four components described in the text. The expected uncertainties in the measurements are also shown.
A search for production of supersymmetric particles in final states containing jets, missing transverse momentum, and at least one hadronically decaying tau lepton is presented. The data were recorded by the ATLAS experiment in sqrt(s) = 7 TeV proton-proton collisions at the Large Hadron Collider. No excess above the Standard Model background expectation was observed in 2.05 fb-1 of data. The results are interpreted in the context of gauge mediated supersymmetry breaking models with Mmess = 250 TeV, N5 = 3, mu > 0, and Cgrav = 1. The production of supersymmetric particles is excluded at 95% C.L. up to a supersymmetry breaking scale Lambda = 30 Tev, independent of tan(beta), and up to Lambda = 43 TeV for large tan(beta).
Distribution of the missing transverse energy before final selection requirement on the effective mass. Tabulated are the observed Data events, the Standard Model predictions and the expected rates for two signal scenarios with Lambda=30TeV / tan(beta) = 20 and Lambda=40GeV / tan(beta)=30 respectively.
Distribution of the tau pt before final selection requirement on the effective mass. Tabulated are the observed Data events, the Standard Model predictions and the expected rates for two signal scenarios with Lambda=30TeV / tan(beta) = 20 and Lambda=40GeV / tan(beta)=30 respectively.
Distribution of the effective mass before final selection requirement on the effective mass. Tabulated are the observed Data events, the Standard Model predictions and the expected rates for two signal scenarios with Lambda=30TeV / tan(beta) = 20 and Lambda=40GeV / tan(beta)=30 respectively.
The results of a search for pair production of the lighter scalar partners of top quarks in 2.05 fb-1 of pp collisions at sqrt(s) =7 TeV using the ATLAS experiment at the LHC are reported. Scalar top quarks are searched for in events with two same flavour opposite-sign leptons (electrons or muons) with invariant mass consistent with the Z boson mass, large missing transverse momentum and jets in the final state. At least one of the jets is identified as originating from a b-quark. No excess over Standard Model expectations is found. The results are interpreted in the framework of R-parity conserving, gauge mediated Supersymmetry breaking `natural' scenarios, where the neutralino is the next-to-lightest supersymmetric particle. Scalar top quark masses up to 310 GeV are excluded for the lightest neutralino mass between 115 GeV and 230 GeV at 95% confidence level, reaching an exclusion of the scalar top quark mass of 330 GeV for the lightest neutralino mass of 190 GeV. Scalar top quark masses below 240 GeV are excluded for all values of the lightest neutralino mass above the Z boson mass.
The missing ET distribution from the combined EE and MUMU data for SR1. Tabulated are the observed Data rates and the Standard Model predictions as well as the distributions expected for two signal scenarios, both with an STOP mass of 250 GeV, and NEUTRALINO1 masses of 100 GeV and 220 GeV respectively.
The number of b-tagged jets for SR1 for the combined EE and MUMU channels. Tabulated are the observed Data rates and the Standard Model predictions as well as the distributions expected for two signal scenarios, both with an STOP mass of 250 GeV, and NEUTRALINO1 masses of 100 GeV and 220 GeV respectively.
The distrubution of leading jet pT for SR1 for the combined EE and MUMU channels. Tabulated are the observed Data rates and the Standard Model predictions as well as the distributions expected for two signal scenarios, both with an STOP mass of 250 GeV, and NEUTRALINO1 masses of 100 GeV and 220 GeV respectively. The last pT bin includes the number of overflow events for both data abd SM expectation.
A search for the weak production of charginos and neutralinos into final states with three electrons or muons and missing transverse momentum is presented. The analysis uses 2.06 fb^-1 of sqrt(s) = 7 TeV proton-proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with standard model expectations in two signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric and simplified models. For the simplified models, degenerate lightest chargino and next-to-lightest neutralino masses up to 300 GeV are excluded for mass differences from the lightest neutralino up to 300 GeV.
Transverse momentum distribution for the first leading lepton for events in the SR1 signal region for DATA and SM predictions.
Transverse momentum distribution for the first leading lepton for events in the SR2 signal region for DATA and SM predictions.
Transverse momentum distribution for the second leading lepton for events in the SR1 signal region for DATA and SM predictions.