Date

Search for supersymmetry in events with four or more leptons in $\sqrt{s}=13$ TeV $pp$ collisions with ATLAS

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Rev.D 98 (2018) 032009, 2018.
Inspire Record 1667045 DOI 10.17182/hepdata.82585

Results from a search for supersymmetry in events with four or more charged leptons (electrons, muons and taus) are presented. The analysis uses a data sample corresponding to 36.1 fb$^{-1}$ of proton-proton collisions delivered by the Large Hadron Collider at $\sqrt{s}=13$ TeV and recorded by the ATLAS detector. Four-lepton signal regions with up to two hadronically decaying taus are designed to target a range of supersymmetric scenarios that can be either enriched in or depleted of events involving the production and decay of a $Z$ boson. Data yields are consistent with Standard Model expectations and results are used to set upper limits on the event yields from processes beyond the Standard Model. Exclusion limits are set at the 95% confidence level in simplified models of General Gauge Mediated supersymmetry, where higgsino masses are excluded up to 295 GeV. In $R$-parity-violating simplified models with decays of the lightest supersymmetric particle to charged leptons, lower limits of 1.46 TeV, 1.06 TeV, and 2.25 TeV are placed on wino, slepton and gluino masses, respectively.

76 data tables

The $m_{\mathrm{eff}}$ distribution for events passing the signal region requirements except the $m_{\mathrm{eff}}$ requirement in SR0A and SR0B. Distributions for data, the estimated SM backgrounds, and an example SUSY scenario are shown. "Other" is the sum of the $tWZ$, $t\bar{t}WW$, and $t\bar{t}t\bar{t}$ backgrounds. The last bin captures the overflow events. Both the statistical and systematic uncertainties in the SM background are included in the shaded band. The red arrows indicate the $m_{\mathrm{eff}}$ selections in the signal regions.

The $E_{\mathrm{T}}^{\mathrm{miss}}$ distribution for events passing the signal region requirements except the $E_{\mathrm{T}}^{\mathrm{miss}}$ requirement in SR0C and SR0D. Distributions for data, the estimated SM backgrounds, and an example SUSY scenario are shown. "Other" is the sum of the $tWZ$, $t\bar{t}WW$, and $t\bar{t}t\bar{t}$ backgrounds. The last bin captures the overflow events. Both the statistical and systematic uncertainties in the SM background are included in the shaded band. The red arrows indicate the $E_{\mathrm{T}}^{\mathrm{miss}}$ selections in the signal regions.

The $m_{\mathrm{eff}}$ distribution for events passing the signal region requirements except the $m_{\mathrm{eff}}$ requirement in SR1. Distributions for data, the estimated SM backgrounds, and an example SUSY scenario are shown. "Other" is the sum of the $tWZ$, $t\bar{t}WW$, and $t\bar{t}t\bar{t}$ backgrounds. The last bin captures the overflow events. Both the statistical and systematic uncertainties in the SM background are included in the shaded band. The red arrows indicate the $m_{\mathrm{eff}}$ selections in the signal region.

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Search for low-mass dijet resonances using trigger-level jets with the ATLAS detector in $pp$ collisions at sqrt(s)=13 TeV

The ATLAS collaboration Aaboud, M. ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Rev.Lett. 121 (2018) 081801, 2018.
Inspire Record 1667040 DOI 10.17182/hepdata.84597

Searches for dijet resonances with sub-TeV masses using the ATLAS detector at the Large Hadron Collider can be statistically limited by the bandwidth available to inclusive single-jet triggers, whose data-collection rates at low transverse momentum are much lower than the rate from Standard Model multijet production. This Letter describes a new search for dijet resonances where this limitation is overcome by recording only the event information calculated by the jet trigger algorithms, thereby allowing much higher event rates with reduced storage needs. The search targets low-mass dijet resonances in the range 450-1800 GeV. The analyzed dataset has an integrated luminosity of up to 29.3 fb$^{-1}$ and was recorded at a center-of-mass energy of 13 TeV. No excesses are found; limits are set on Gaussian-shaped contributions to the dijet mass distribution from new particles and on a model of dark-matter particles with axial-vector couplings to quarks.

6 data tables

Data, estimated background and uncertainties, in the region defined by |y*|<0.3.

Data, estimated background and uncertainties, in the region defined by |y*|<0.6.

Observed 95% CL limit on cross section times acceptance times branching ratio for each width and mass of Gaussian signal shape tested, in the region defined by |y*|<0.3.

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Measurement of differential cross sections for Z boson production in association with jets in proton-proton collisions at $\sqrt{s} =$ 13 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Eur.Phys.J.C 78 (2018) 965, 2018.
Inspire Record 1667854 DOI 10.17182/hepdata.91404

The production of a Z boson, decaying to two charged leptons, in association with jets in proton-proton collisions at a centre-of-mass energy of 13 TeV is measured. Data recorded with the CMS detector at the LHC are used that correspond to an integrated luminosity of 2.19 fb$^{-1}$. The cross section is measured as a function of the jet multiplicity and its dependence on the transverse momentum of the Z boson, the jet kinematic variables (transverse momentum and rapidity), the scalar sum of the jet momenta, which quantifies the hadronic activity, and the balance in transverse momentum between the reconstructed jet recoil and the Z boson. The measurements are compared with predictions from four different calculations. The first two merge matrix elements with different parton multiplicities in the final state and parton showering, one of which includes one-loop corrections. The third is a fixed-order calculation with next-to-next-to-leading order accuracy for the process with a Z boson and one parton in the final state. The fourth combines the fully differential next-to-next-to-leading order calculation with next-to-next-to-leading logarithm resummation and parton showering.

36 data tables

Measured cross section for Z+jets as a function of the exclusive jet multiplicity, $N_{\text{jets}}$, and breakdown of the relative uncertainty.

Bin-to-bin correlation in the measured cross section for Z+jets as a function of the exclusive jet multiplicity, $N_{\text{jets}}$.

Measured cross section for Z+jets as a function of inclusive jet multiplicity, $N_{\text{jets}}^{\text{min}}$, and breakdown of the relative uncertainty.

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Search for pair production of Higgs bosons in the $b\bar{b}b\bar{b}$ final state using proton-proton collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
JHEP 01 (2019) 030, 2019.
Inspire Record 1668124 DOI 10.17182/hepdata.82599

A search for Higgs boson pair production in the $b\bar{b}b\bar{b}$ final state is carried out with up to 36.1 $\mathrm{fb}^{-1}$ of LHC proton--proton collision data collected at $\sqrt{s}$ = 13 TeV with the ATLAS detector in 2015 and 2016. Three benchmark signals are studied: a spin-2 graviton decaying into a Higgs boson pair, a scalar resonance decaying into a Higgs boson pair, and Standard Model non-resonant Higgs boson pair production. Two analyses are carried out, each implementing a particular technique for the event reconstruction that targets Higgs bosons reconstructed as pairs of jets or single boosted jets. The resonance mass range covered is 260--3000 GeV. The analyses are statistically combined and upper limits on the production cross section of Higgs boson pairs times branching ratio to $b\bar{b}b\bar{b}$ are set in each model. No significant excess is observed; the largest deviation of data over prediction is found at a mass of 280 GeV, corresponding to 2.3 standard deviations globally. The observed 95% confidence level upper limit on the non-resonant production is 13 times the Standard Model prediction.

4 data tables

The observed and expected 95% CL upper limits on the production cross section times branching ratio for the narrow-width scalar.

The observed and expected 95% CL upper limits on the production cross section times branching ratio for the bulk Randall-Sundrum model with $\frac{k}{\overline{M}_{\mathrm{Pl}}} = 1$.

The observed and expected 95% CL upper limits on the production cross section times branching ratio for the bulk Randall-Sundrum model with $\frac{k}{\overline{M}_{\mathrm{Pl}}} = 2$.

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Search for disappearing tracks as a signature of new long-lived particles in proton-proton collisions at $\sqrt{s} =$ 13 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
JHEP 08 (2018) 016, 2018.
Inspire Record 1669245 DOI 10.17182/hepdata.84707

A search is presented for long-lived charged particles that decay within the CMS detector and produce the signature of a disappearing track. A disappearing track is an isolated track with missing hits in the outer layers of the silicon tracker, little or no energy in associated calorimeter deposits, and no associated hits in the muon detectors. This search uses data collected with the CMS detector in 2015 and 2016 from proton-proton collisions at a center-of-mass energy of 13 TeV at the LHC, corresponding to an integrated luminosity of 38.4 fb$^{-1}$. The results of the search are interpreted in the context of the anomaly-mediated supersymmetry breaking model. The data are consistent with the background-only hypothesis. Limits are set on the product of the cross section for direct production of charginos and their branching fraction to a neutralino and a pion, as a function of the chargino mass and lifetime. At 95% confidence level, charginos with masses below 715 (695) GeV are excluded for a lifetime of 3 (7) ns, as are charginos with lifetimes from 0.5 to 60 ns for a mass of 505 GeV. These are the most stringent limits using a disappearing track signature on this signal model for chargino lifetimes above $\approx$ 0.7 ns.

14 data tables

The expected and observed 95% CL upper limits on the product of the cross section for direct production of charginos and their branching fraction to $\widetilde{\chi}^{0}_{1}\mathrm{\pi^{\pm}}$ as a function of chargino mass for a chargino lifetime of 0.3 ns. The ratio of the vacuum expectation values of the two Higgs doublets, $\tan \beta$, is fixed to 5 with $\mu > 0$, where $\mu$ is the higgsino mass parameter. The direct chargino production cross section includes both $\widetilde{\chi}^{0}_{1}\widetilde{\chi}^\pm_{1}$ and $\widetilde{\chi}^\pm_{1}\widetilde{\chi}^\mp_{1}$ production in roughly a 2:1 ratio for all chargino masses considered, and the branching fraction of $\widetilde{\chi}^\pm_{1} \rightarrow \widetilde{\chi}^{0}_{1}\mathrm{\pi^{\pm}}$ is set to 100%. The theoretical prediction for the AMSB model is also shown.

The expected and observed 95% CL upper limits on the product of the cross section for direct production of charginos and their branching fraction to $\widetilde{\chi}^{0}_{1}\mathrm{\pi^{\pm}}$ as a function of chargino mass for a chargino lifetime of 3.3 ns. The ratio of the vacuum expectation values of the two Higgs doublets, $\tan \beta$, is fixed to 5 with $\mu > 0$, where $\mu$ is the higgsino mass parameter. The direct chargino production cross section includes both $\widetilde{\chi}^{0}_{1}\widetilde{\chi}^\pm_{1}$ and $\widetilde{\chi}^\pm_{1}\widetilde{\chi}^\mp_{1}$ production in roughly a 2:1 ratio for all chargino masses considered, and the branching fraction of $\widetilde{\chi}^\pm_{1} \rightarrow \widetilde{\chi}^{0}_{1}\mathrm{\pi^{\pm}}$ is set to 100%. The theoretical prediction for the AMSB model is also shown.

The expected and observed 95% CL upper limits on the product of the cross section for direct production of charginos and their branching fraction to $\widetilde{\chi}^{0}_{1}\mathrm{\pi^{\pm}}$ as a function of chargino mass for a chargino lifetime of 33 ns. The ratio of the vacuum expectation values of the two Higgs doublets, $\tan \beta$, is fixed to 5 with $\mu > 0$, where $\mu$ is the higgsino mass parameter. The direct chargino production cross section includes both $\widetilde{\chi}^{0}_{1}\widetilde{\chi}^\pm_{1}$ and $\widetilde{\chi}^\pm_{1}\widetilde{\chi}^\mp_{1}$ production in roughly a 2:1 ratio for all chargino masses considered, and the branching fraction of $\widetilde{\chi}^\pm_{1} \rightarrow \widetilde{\chi}^{0}_{1}\mathrm{\pi^{\pm}}$ is set to 100%. The theoretical prediction for the AMSB model is also shown.

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Beam energy dependence of rapidity-even dipolar flow in Au+Au collisions

The STAR collaboration Adam, J. ; Adamczyk, Leszek ; Adams, Joseph ; et al.
Phys.Lett.B 784 (2018) 26-32, 2018.
Inspire Record 1669807 DOI 10.17182/hepdata.100168

New measurements of directed flow for charged hadrons, characterized by the Fourier coefficient \vone, are presented for transverse momenta $\mathrm{p_T}$, and centrality intervals in Au+Au collisions recorded by the STAR experiment for the center-of-mass energy range $\mathrm{\sqrt{s_{_{NN}}}} = 7.7 - 200$ GeV. The measurements underscore the importance of momentum conservation and the characteristic dependencies on $\mathrm{\sqrt{s_{_{NN}}}}$, centrality and $\mathrm{p_T}$ are consistent with the expectations of geometric fluctuations generated in the initial stages of the collision, acting in concert with a hydrodynamic-like expansion. The centrality and $\mathrm{p_T}$ dependencies of $\mathrm{v^{even}_{1}}$, as well as an observed similarity between its excitation function and that for $\mathrm{v_3}$, could serve as constraints for initial-state models. The $\mathrm{v^{even}_{1}}$ excitation function could also provide an important supplement to the flow measurements employed for precision extraction of the temperature dependence of the specific shear viscosity.

5 data tables

$v_{11}$ vs. $p_{T}^{b}$ for several selections of $p_{T}^{a}$ for 0-5 central Au+Au collisions at $\sqrt{s_{_{NN}}} = 200$ GeV. The curve shows the result of the simultaneous fit.

Extracted values of $v^{even}_{1}$ vs. $p_{T}$ for 0-10 central Au+Au collisions for several values of $\sqrt{s_{_{NN}}}$ as indicated; the $v^{even}_{1}$ values are obtained via fits. The curve in panel (a) shows the result from a viscous hydrodynamically based predictions.

(a) Centrality dependence of $v^{even}_{1}$ for $0.4 \lt p_{T} \lt 0.7$ GeV/c for Au+Au collisions at $\sqrt{s_{_{NN}}} = 200, 39$ and $19.6$ GeV; (b) $K$ vs. $\langle N_{ch} \rangle^{-1}$ for the $v^{even}_{1}$ values shown in (a). The $\langle N_{ch} \rangle$ values correspond to the centrality intervals indicated in panel (a).

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Elliptic flow of charm and strange hadrons in high-multiplicity pPb collisions at $\sqrt{s_{_\mathrm{NN}}} =$ 8.16 TeV

The CMS collaboration Sirunyan, A. M. ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Rev.Lett. 121 (2018) 082301, 2018.
Inspire Record 1670168 DOI 10.17182/hepdata.83911

The elliptic azimuthal anisotropy coefficient ($v_2$) is measured for charm (D$^0$) and strange (K$_\mathrm{S}^0$, $\Lambda$, $\Xi^-$, and $\Omega^-$) hadrons, using a data sample of pPb collisions collected by the CMS experiment, at a nucleon-nucleon center-of-mass energy $\sqrt{s_{_\mathrm{NN}}} =$ 8.16 TeV. A significant positive $v_2$ signal from long-range azimuthal correlations is observed for all particle species in high-multiplicity pPb collisions. The measurement represents the first observation of possible long-range collectivity for open heavy flavor hadrons in small systems. The results suggest that charm quarks have a smaller $v_2$ than the lighter quarks, probably reflecting a weaker collective behavior. This effect is not seen in the larger PbPb collision system at $\sqrt{s_{_\mathrm{NN}}} =$ 5.02 TeV, also presented.

24 data tables

The elliptic flow, $v_{2}$, for $K^{0}_{S}$ as a function of $p_{T}$ in pPb collision at 8.16 TeV.

The elliptic flow, $v_{2}$, for $\Lambda$ as a function of $p_{T}$ in pPb collision at 8.16 TeV.

The elliptic flow, $v_{2}$, for $\Xi^{-}$ as a function of $p_{T}$ in pPb collision at 8.16 TeV.

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Measurement of the top quark mass with lepton+jets final states using pp collisions at $\sqrt{s}=$ 13 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Eur.Phys.J.C 78 (2018) 891, 2018.
Inspire Record 1671499 DOI 10.17182/hepdata.85702

The mass of the top quark is measured using a sample of $\mathrm{t\overline{t}}$ events collected by the CMS detector using proton-proton collisions at $\sqrt{s} =$ 13 TeV at the CERN LHC. Events are selected with one isolated muon or electron and at least four jets from data corresponding to an integrated luminosity of 35.9 fb$^{-1}$. For each event the mass is reconstructed from a kinematic fit of the decay products to a $\mathrm{t\overline{t}}$ hypothesis. Using the ideogram method, the top quark mass is determined simultaneously with an overall jet energy scale factor (JSF), constrained by the mass of the W boson in $\mathrm{q\overline{q}'}$ decays. The measurement is calibrated on samples simulated at next-to-leading order matched to a leading-order parton shower. The top quark mass is found to be 172.25 $\pm$ 0.08 (stat+JSF) $\pm$ 0.62 (syst) GeV. The dependence of this result on the kinematic properties of the event is studied and compared to predictions of different models of $\mathrm{t\overline{t}}$ production, and no indications of a bias in the measurements are observed.

1 data table

Measured top quark mass $m_{t}$


Version 3
Search for supersymmetry in final states with charm jets and missing transverse momentum in 13 TeV $pp$ collisions with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
JHEP 09 (2018) 050, 2018.
Inspire Record 1672099 DOI 10.17182/hepdata.83011

A search for supersymmetric partners of top quarks decaying as $\tilde{t}_1\to c\tilde\chi^0_1$ and supersymmetric partners of charm quarks decaying as $\tilde{c}_1\to c\tilde\chi^0_1$, where $\tilde\chi^0_1$ is the lightest neutralino, is presented. The search uses 36.1 ${\rm fb}^{-1}$ $pp$ collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS experiment at the Large Hadron Collider and is performed in final states with jets identified as containing charm hadrons. Assuming a 100% branching ratio to $c\tilde\chi^0_1$, top and charm squarks with masses up to 850 GeV are excluded at 95% confidence level for a massless lightest neutralino. For $m_{\tilde{t}_1,\tilde{c}_1}-m_{\tilde\chi^0_1}

44 data tables

Acceptance for SR1 in the $\tilde{t}_1/\tilde{c}_1-\tilde{\chi}_1^0$ mass plane.

Acceptance for SR2 in the $\tilde{t}_1/\tilde{c}_1-\tilde{\chi}_1^0$ mass plane.

Acceptance for SR3 in the $\tilde{t}_1/\tilde{c}_1-\tilde{\chi}_1^0$ mass plane.

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Search for heavy resonances decaying to a photon and a hadronically decaying $Z/W/H$ boson in $pp$ collisions at $\sqrt{s}=13$ $\mathrm{TeV}$ with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Rev.D 98 (2018) 032015, 2018.
Inspire Record 1672010 DOI 10.17182/hepdata.82605

Many extensions of the Standard Model predict new resonances decaying to a $Z$, $W$, or Higgs boson and a photon. This paper presents a search for such resonances produced in $pp$ collisions at $\sqrt{s} = 13$ $\mathrm{TeV}$ using a dataset with an integrated luminosity of 36.1 fb$^{-1}$ collected by the ATLAS detector at the Large Hadron Collider. The $Z/W/H$ bosons are identified through their decays to hadrons. The data are found to be consistent with the Standard Model expectation in the entire investigated mass range. Upper limits are set on the production cross section times branching fraction for resonance decays to $Z/W+\gamma$ in the mass range from 1.0 to 6.8 $\mathrm{TeV}$, and for the first time into $H+\gamma$ in the mass range from 1.0 to 3.0 $\mathrm{TeV}$.

18 data tables

Efficiencies for gg->X(J=0)->Zgamma signal events to pass the category selections as a function of the resonance mass.

Efficiencies for qqbar->X(J=2)->Zgamma signal events to pass the category selections as a function of the resonance mass.

Efficiencies for gg->X(J=2)->Zgamma signal events to pass the category selections as a function of the resonance mass.

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