Abstract
The most recent CMS results from a search for supersymmetry (SUSY) with a compressed mass spectrum in leptonic final states will be presented. The search is targeting signatures with missing ...transverse momentum and two or three low-momentum (soft) leptons. The dataset used is collected by the CMS experiment during the Run–2 proton-proton collisions at
s
=
13
TeV at the LHC, and corresponds to an integrated luminosity of up to 137 fb
−1
. The observed data are found to be in agreement with the Standard Model prediction and exclusion upper limits are set on the SUSY particles production cross section. The results are interpreted in terms of electroweakino and top squark pair production. In both cases, a small mass difference between the produced SUSY particles and the lightest neutralino is considered. A wino-bino and a higgsino simplified models are used for the electroweakino interpretation. Exclusion limits at 95% confidence level are set on
x
˜
2
0
/
x
˜
1
±
masses up to 280 GeV for a mass difference between the
x
˜
2
0
/
x
˜
1
±
and the lightest neutralino of 10 GeV for the wino-bino production. In the higgsino interpretation
x
˜
2
0
/
x
˜
1
±
masses are excluded up to 210 GeV for a mass difference of 7.5 GeV and up to 150 GeV for a mass difference of 3 GeV. The results for the higgsino production are additionally interpreted in terms of a phenomenological minimal SUSY extension of the standard model, excluding the higgsino mass parameter
μ
up to 180 GeV for bino mass parameter
M
1
= 800 GeV. Upper limits at 95% confidence level are set on the top squark pair production interpretation, excluding top squark masses up to 530 GeV in the four-body top squark decay model and up to 475 GeV in the chargino-mediated decay model for a mass difference between the top squark and the lightest neutralino of 30 GeV.
Between the years 2015 and 2019, members of the Horizon 2020-funded Innovative Training Network named “AMVA4NewPhysics” studied the customization and application of advanced multivariate analysis ...methods and statistical learning tools to high-energy physics problems, as well as developed entirely new ones. Many of those methods were successfully used to improve the sensitivity of data analyses performed by the ATLAS and CMS experiments at the CERN Large Hadron Collider; several others, still in the testing phase, promise to further improve the precision of measurements of fundamental physics parameters and the reach of searches for new phenomena. In this paper, the most relevant new tools, among those studied and developed, are presented along with the evaluation of their performances.
2021 J. Phys.: Conf. Ser. 2105 012012 The most recent CMS results from a search for supersymmetry (SUSY) with a
compressed mass spectrum in leptonic final states will be presented. The search
is ...targeting signatures with missing transverse momentum and two or three
low-momentum (soft) leptons. The dataset used is collected by the CMS
experiment during the Run-2 p-p collisions at $\sqrt{s} = {}$13 TeV at the LHC,
and corresponds to an integrated luminosity of up to 137 fb$^{-1}$. The
observed data are found to be in agreement with the standard model (SM)
prediction and exclusion upper limits are set on the SUSY particles production
cross section. The results are interpreted in terms of electroweakino and top
squark pair production. In both cases, a small mass difference between the
produced SUSY particles and the lightest neutralino is considered. A wino-bino
and a higgsino simplified models are used for the electroweakino
interpretation. Exclusion limits at 95% confidence level are set on
$\tilde{\chi}_{2}^{0}$/$\tilde{\chi}_{1}^{\pm}$ masses up to 280 GeV for a mass
difference between the $\tilde{\chi}_{2}^{0}$/$\tilde{\chi}_{1}^{\pm}$ and the
lightest neutralino of 10 GeV for the wino-bino production. In the higgsino
interpretation $\tilde{\chi}_{2}^{0}$/$\tilde{\chi}_{1}^{\pm}$ masses are
excluded up to 210(150) GeV for a mass difference of 7.5(3) GeV. The results
for the higgsino production are additionally interpreted in terms of a
phenomenological minimal SUSY extension of the SM, excluding the higgsino mass
parameter $\mu$ up to 180 GeV for bino mass parameter $M_1 = {}$800 GeV. Upper
limits at 95% confidence level are set on the top squark pair production
interpretation, excluding top squark masses up to 530 GeV in the four-body top
squark decay model and up to 475 GeV in the chargino-mediated decay model for a
mass difference between the top squark and the lightest neutralino of 30 GeV.
The most recent CMS results from a search for supersymmetry (SUSY) with a compressed mass spectrum in leptonic final states will be presented. The search is targeting signatures with missing ...transverse momentum and two or three low-momentum (soft) leptons. The dataset used is collected by the CMS experiment during the Run-2 p-p collisions at \(\sqrt{s} = {}\)13 TeV at the LHC, and corresponds to an integrated luminosity of up to 137 fb\(^{-1}\). The observed data are found to be in agreement with the standard model (SM) prediction and exclusion upper limits are set on the SUSY particles production cross section. The results are interpreted in terms of electroweakino and top squark pair production. In both cases, a small mass difference between the produced SUSY particles and the lightest neutralino is considered. A wino-bino and a higgsino simplified models are used for the electroweakino interpretation. Exclusion limits at 95% confidence level are set on \(\tilde{\chi}_{2}^{0}\)/\(\tilde{\chi}_{1}^{\pm}\) masses up to 280 GeV for a mass difference between the \(\tilde{\chi}_{2}^{0}\)/\(\tilde{\chi}_{1}^{\pm}\) and the lightest neutralino of 10 GeV for the wino-bino production. In the higgsino interpretation \(\tilde{\chi}_{2}^{0}\)/\(\tilde{\chi}_{1}^{\pm}\) masses are excluded up to 210(150) GeV for a mass difference of 7.5(3) GeV. The results for the higgsino production are additionally interpreted in terms of a phenomenological minimal SUSY extension of the SM, excluding the higgsino mass parameter \(\mu\) up to 180 GeV for bino mass parameter \(M_1 = {}\)800 GeV. Upper limits at 95% confidence level are set on the top squark pair production interpretation, excluding top squark masses up to 530 GeV in the four-body top squark decay model and up to 475 GeV in the chargino-mediated decay model for a mass difference between the top squark and the lightest neutralino of 30 GeV.
Between the years 2015 and 2019, members of the Horizon 2020-funded Innovative Training Network named "AMVA4NewPhysics" studied the customization and application of advanced multivariate analysis ...methods and statistical learning tools to high-energy physics problems, as well as developed entirely new ones. Many of those methods were successfully used to improve the sensitivity of data analyses performed by the ATLAS and CMS experiments at the CERN Large Hadron Collider; several others, still in the testing phase, promise to further improve the precision of measurements of fundamental physics parameters and the reach of searches for new phenomena. In this paper, the most relevant new tools, among those studied and developed, are presented along with the evaluation of their performances.
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