A summary of the constraints from searches performed by the ATLAS Collaboration for the electroweak production of charginos and neutralinos is presented. Results from eight separate ATLAS searches are considered, each using 140 fb$^{-1}$ of proton-proton data at a centre-of-mass energy of $\sqrt{s}$=13 TeV collected at the Large Hadron Collider during its second data-taking run. The results are interpreted in the context of the 19-parameter phenomenological minimal supersymmetric standard model, where R-parity conservation is assumed and the lightest supersymmetric particle is assumed to be the lightest neutralino. Constraints from previous electroweak, flavour and dark matter related measurements are also considered. The results are presented in terms of constraints on supersymmetric particle masses and are compared with limits from simplified models. Also shown is the impact of ATLAS searches on parameters such as the dark matter relic density and the spin-dependent and spin-independent scattering cross-sections targeted by direct dark matter detection experiments. The Higgs boson and Z boson `funnel regions', where a low-mass neutralino would not oversaturate the dark matter relic abundance, are almost completely excluded by the considered constraints. Example spectra for non-excluded supersymmetric models with light charginos and neutralinos are also presented.
SLHA files and exclusion information (in CSV format) are available to download for the pMSSM models in this paper. Please refer to <a href="https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/SUSY-2020-15/inputs/ATLAS_EW_pMSSM_Run2.html">this web page</a> for download links along with a description of the contents.
SLHA files and exclusion information (in CSV format) are available to download for the pMSSM models in this paper. Please refer to <a href="https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/SUSY-2020-15/inputs/ATLAS_EW_pMSSM_Run2.html">this web page</a> for download links along with a description of the contents.
We perform a low-mass dark matter search using an exposure of 30\,kg$\times$yr with the XENON100 detector. By dropping the requirement of a scintillation signal and using only the ionization signal to determine the interaction energy, we lowered the energy threshold for detection to 0.7\,keV for nuclear recoils. No dark matter detection can be claimed because a complete background model cannot be constructed without a primary scintillation signal. Instead, we compute an upper limit on the WIMP-nucleon scattering cross section under the assumption that every event passing our selection criteria could be a signal event. Using an energy interval from 0.7\,keV to 9.1\,keV, we derive a limit on the spin-independent WIMP-nucleon cross section that excludes WIMPs with a mass of 6\,GeV/$c^2$ above $1.4 \times 10^{-41}$\,cm$^2$ at 90\% confidence level.
WIMP exclusion limit on the spin-independent WIMP-nucleon scattering cross section at 90% confidence level.
The parity-violating asymmetries between a longitudinally-polarized electron beam and an unpolarized deuterium target have been measured recently. The measurement covered two kinematic points in the deep inelastic scattering region and five in the nucleon resonance region. We provide here details of the experimental setup, data analysis, and results on all asymmetry measurements including parity-violating electron asymmetries and those of inclusive pion production and beam-normal asymmetries. The parity-violating deep-inelastic asymmetries were used to extract the electron-quark weak effective couplings, and the resonance asymmetries provided the first evidence for quark-hadron duality in electroweak observables. These electron asymmetries and their interpretation were published earlier, but are presented here in more detail.
Asymmetry results on $\vec e-^2$H parity-violating scattering from the PVDIS experiment at JLab.
Asymmetry results on $\vec e-^2$H parity-violating scattering from the PVDIS experiment at JLab, for RES I settings.
Asymmetry results on $\vec e-^2$H parity-violating scattering from the PVDIS experiment at JLab, for RES II settings.
Measurements of the muon charge asymmetry in inclusive pp to WX production at sqrt(s) = 7 TeV are presented. The data sample corresponds to an integrated luminosity of 4.7 inverse femtobarns recorded with the CMS detector at the LHC. With a sample of more than twenty million W to mu nu events, the statistical precision is greatly improved in comparison to previous measurements. These new results provide additional constraints on the parton distribution functions of the proton in the range of the Bjorken scaling variable x from 10E-3 to 10E-1. These measurements and the recent CMS measurement of associated W + charm production are used together with the cross sections for inclusive deep inelastic ep scattering at HERA in a next-to-leading-order QCD analysis. The determination of the valence quark distributions is improved, and the strange-quark distribution is probed directly through the leading-order process g + s to W + c in proton-proton collisions at the LHC.
Summary of the final results for muon charge asymmetry $\mathcal{A}$ with the muon $p_{T}>25$ GeV. The first uncertainty is statistical and the second is systematic. The theoretical predictions are obtained using the FEWZ 3.1 MC tool interfaced with the NLO CT10, NNPDF2.3, HERAPDF1.5, and MSTW2008CPdeut PDF sets. The PDF uncertainty is at 68% C.L. The values are expressed as percentages.
Summary of the final results for muon charge asymmetry $\mathcal{A}$ with the muon $p_{T}>35$ GeV. The first uncertainty is statistical and the second is systematic. The theoretical predictions are obtained using the FEWZ 3.1 MC tool interfaced with the NLO CT10, NNPDF2.3, HERAPDF1.5, and MSTW2008CPdeut PDF sets. The PDF uncertainty is at 68% C.L. The values are expressed as percentages.
Covariance matrix (statistical and systematic uncertainties combined) with the muon $p_{T}>25$ GeV. The units are in $10^{-4}$.
We report the first measurement of the net-charge fluctuations in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV, measured with the ALICE detector at the CERN Large Hadron Collider. The dynamical fluctuations per unit entropy are observed to decrease when going from peripheral to central collisions. An additional reduction in the amount of fluctuations is seen in comparison to the results from lower energies. We examine the dependence of fluctuations on the pseudorapidity interval, which may account for the dilution of fluctuations during the evolution of the system. We find that the fluctuations at LHC are smaller compared to the measurements at the Relativistic heavy Ion Collider (RHIC), and as such, closer to what has been theoretically predicted for the formation of Quark-Gluon Plasma (QGP).
The measured NU(+-DYN) as a function of the centrality of the collisions, expressed as the number of participating nucleons, for two values of midrapidity range.
NU(+-DYN), corrected for charge conservation and finite acceptance effects, as a function of the centrality of the collisions, expressed as the number of participating nucleons, for two values of midrapidity range.
The measured and corrected NU(+-DYN) in P P collisions for two values of midrapidity range.
Decays of $b$ hadrons into final states containing a $D^0$ meson and a muon are used to measure the $b\bar{b}$ production cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC. In the pseudorapidity interval $2 < \eta < 6$ and integrated over all transverse momenta we find that the average cross-section to produce $b$-flavoured or $\bar{b}$-flavoured hadrons is ($75.3 \pm 5.4 \pm 13.0$) microbarns.
The cross section for b-flavoured hadrons (HADRON/B) as a function of pseudorapidity in proton-proton collisions at a centre-of-mass energy of 7 TeV. Cross sections are shown using fragmentation fractions both from LEP and from the Tevatron. See comment above regarding this latter point.
The cross section for b-flavoured hadrons (HADRON/B) over the pseudorapidity range 2.0-6.0 in proton-proton collisions at a centre-of-mass energy of 7 TeV. Cross sections are shown using fragmentation fractions both from LEP and from the Tevatron. See comment above regarding this latter point.
We present a Next-to-Leading order perturbative QCD analysis of world data on the spin dependent structure functions $g_1^p, g_1^n$, and $g_1^d$, including the new experimental information on the $Q^2$ dependence of $g_1^n$. Careful attention is paid to the experimental and theoretical uncertainties. The data constrain the first moments of the polarized valence quark distributions, but only qualitatively constrain the polarized sea quark and gluon distributions. The NLO results are used to determine the $Q^2$ dependence of the ratio $g_1/F_1$ and evolve the experimental data to a constant $Q^2 = 5 GeV^2$. We determine the first moments of the polarized structure functions of the proton and neutron and find agreement with the Bjorken sum rule.
Data from the 2.75 degree spectrometer.
Data from the 2.75 degree spectrometer evolved to a mean Q**2 of 5 GeV**2 using the MSBAR parameterization. The second systematic error is due to the evolution.
Data from the 5.5 degree spectrometer.
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