Probing bilinear R-parity violating supergravity at the LHC (original) (raw)
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Searches for R-parity violating Supersymmetry at LEP II
sites.huji.ac.il
Results are presented from searches for R-parity-violating supersymmetry in events produced in pp collisions at √ s = 8 TeV at the LHC. Final states with 0, 1, 2, or multiple leptons are considered independently. The analysis is performed on data collected by the CMS experiment corresponding to an integrated luminosity of 19.5 fb −1. No excesses of events above the standard model expectations are observed, and 95% confidence level limits are set on supersymmetric particle masses and production cross sections. The results are interpreted in models featuring R-parity-violating decays of the lightest supersymmetric particle, which in the studied scenarios can be either the gluino, a bottom squark, or a neutralino. In a gluino pair production model with baryon number violation, gluinos with a mass less than 0.98 and 1.03 TeV are excluded, by analyses in a fully hadronic and one-lepton final state, respectively. An analysis in a dilepton final state is used to exclude bottom squarks with masses less than 307 GeV in a model considering bottom squark pair production. Multilepton final states are considered in the context of either strong or electroweak production of superpartners and are used to set limits on the masses of the lightest supersymmetric particles. These limits range from 300 to 900 GeV in models with leptonic and up to approximately 700 GeV in models with semileptonic R-parity-violating couplings.
Can R-parity violation hide vanilla supersymmetry at the LHC?
Journal of High Energy Physics, 2013
Current experimental constraints on a large parameter space in supersymmetric models rely on the large missing energy signature. This is usually provided by the lightest neutralino which stability is ensured by R-parity. However, if R-parity is violated, the lightest neutralino decays into the standard model particles and the missing energy cut is not efficient anymore. In particular, the U DD type R-parity violation induces the neutralino decay to three quarks which potentially leads to the most difficult signal to be searched at hadron colliders. In this paper, we study the constraints on R-parity violating supersymmetric models using a same-sign dilepton and a multijet signatures. We show that the gluino and squarks lighter than TeV are already excluded in the constrained minimal supersymmetric standard model with the R-parity violation if their masses are approximately equal. We also analyze constraints in a simplified model with the R-parity violation. We compare how the R-parity violation changes some of the observables typically used to distinguish a supersymmetric signal from standard model backgrounds.
Probing R-parity violating models of neutrino mass at the LHC
2012
It is shown that the R-parity violating decays of the lighter top squarks (t 1) triggered by the lepton number violating couplings λ ′ i33 , where the lepton family index i = 1-3, can be observed at the LHC via the dilepton di-jet channel even if the coupling is as small as 10 −4 or 10 −5 , which is the case in several models of neutrino mass, provided it is the next lightest supersymmetric particle(NLSP) the lightest neutralino being the lightest supersymmetric particle(LSP). We have first obtained a fairly model independent estimate of the minimum observable value of the parameter (P ij ≡ BR(t → l + i b)×BR(t * → l − jb)) at the LHC for an integrated luminosity of 10fb −1 as a function of m t 1 by a standard Pythia based analysis. We have then computed the parameter P ij in several representative models of neutrino mass constrained by the neutrino oscillation data and have found that the theoretical predictions are above the estimated minimum observable levels for a wide region of the parameter space.
Supersymmetry with Trilinear R-Parity Violation at the LHC
2011
The inclusion of trilinear R-parity violating couplings in a supersymmetric theory, has monumental impacts on the phenomenology. Regarding LHC physics, we no longer expect events with a lot of missing transverse energy, but events with large lepton and/or jet multiplicity. Here we present a study where the standard MSSM scenario of squark and gluino pair production and consequent cascade decay to the neutralino, is followed by a three-body decay of the neutralino through any of the 45 allowed trilinear R-parity violating operators. This allows us to study all these operators and detect any hierarchies among them as well as measuring the neutralino mass.
Probing neutralino properties in minimal supergravity with bilinear R-parity violation
Physical Review D, 2012
Supersymmetric models with bilinear R-parity violation (BRPV) can account for the observed neutrino masses and mixing parameters indicated by neutrino oscillation data. We consider minimal supergravity versions of BRPV where the lightest supersymmetric particle (LSP) is a neutralino. This is unstable, with a large enough decay length to be detected at the CERN Large Hadron Collider (LHC). We analyze the LHC potential to determine the LSP properties, such as mass, lifetime and branching ratios, and discuss their relation to neutrino properties.
Physical Review D, 2017
Results are reported from a search for R-parity violating supersymmetry in protonproton collision events collected by the CMS experiment at a center-of-mass energy of √ s = 8 TeV. The data sample corresponds to an integrated luminosity of 17.6 fb −1. This search assumes a minimal flavor violating model in which the lightest supersymmetric particle is a long-lived neutralino or gluino, leading to a signal with jets emanating from displaced vertices. In a sample of events with two displaced vertices, no excess yield above the expectation from standard model processes is observed, and limits are placed on the pair production cross section as a function of mass and lifetime of the neutralino or gluino. At 95% confidence level, the analysis excludes cross sections above approximately 1 fb for neutralinos or gluinos with mass between 400 and 1500 GeV and mean proper decay length between 1 and 30 mm. Gluino masses are excluded below 1 and 1.3 TeV for mean proper decay lengths of 300 µm and 1 mm, respectively, and below 1.4 TeV for the range 2-30 mm. The results are also applicable to other models in which long-lived particles decay into multijet final states.
ProbingR-parity violating models of neutrino mass at the LHC via top squark decays
Physical Review D, 2009
It is shown that the R-parity violating decays of the lighter top squarks (t 1) triggered by the lepton number violating couplings λ ′ i33 , where the lepton family index i = 1-3, can be observed at the LHC via the dilepton di-jet channel even if the coupling is as small as 10 −4 or 10 −5 , which is the case in several models of neutrino mass, provided it is the next lightest supersymmetric particle(NLSP) the lightest neutralino being the lightest supersymmetric particle(LSP). We have first obtained a fairly model independent estimate of the minimum observable value of the parameter (P ij ≡ BR(t → l + i b)×BR(t * → l − jb)) at the LHC for an integrated luminosity of 10fb −1 as a function of m t 1 by a standard Pythia based analysis. We have then computed the parameter P ij in several representative models of neutrino mass constrained by the neutrino oscillation data and have found that the theoretical predictions are above the estimated minimum observable levels for a wide region of the parameter space.
Search for R-Parity Violating Supersymmetry in the Dielectron Channel
Physical Review Letters, 1999
We present results of a search for R-parity-violating decay of the neutralino 0 1 , taken as the lightest supersymmetric particle, to a muon and two jets. The decay proceeds through a lepton-number violating coupling 0 2jk (j 1; 2; k 1; 2; 3), with R-parity conservation in all other production and decay processes. In the absence of candidate events from 77:5 3:9 pb ÿ1 of data collected by the D0 experiment at the Fermilab Tevatron in pp collisions at s p 1:8 TeV, and with an expected background of 0:18 0:03 0:02 events, we set limits on squark and gluino masses within the framework of the minimal low-energy supergravity-supersymmetry model.
Neutrino Oscillations and Collider Test of the R-parity Violating Minimal Supergravity Model
Journal of High Energy Physics, 2004
We study the R-parity violating minimal supergravity models accounting for the observed neutrino masses and mixing, which can be tested in future collider experiments. The bi-large mixing can be explained by allowing five dominant tri-linear couplings λ ′ 1,2,3 and λ1,2. The desired ratio of the atmospheric and solar neutrino mass-squared differences can be obtained in a very limited parameter space where the tree-level contribution is tuned to be suppressed. In this allowed region, we quantify the correlation between the three neutrino mixing angles and the tri-linear R-parity violating couplings. Qualitatively, the relations |λ ′ 1 | < |λ ′ 2 | ∼ |λ ′ 3 |, and |λ1| ∼ |λ2| are required by the large atmospheric neutrino mixing angle θ23 and the small angle θ13, and the large solar neutrino mixing angle θ12, respectively. Such a prediction on the couplings can be tested in the next linear colliders by observing the branching ratios of the lightest supersymmetric particle (LSP). For the stau or the neutralino LSP, the ratio |λ1| 2 : |λ2| 2 : |λ1| 2 + |λ2| 2 can be measured by establishing Br(eν) : Br(µν) : Br(τ ν) or Br(νe ± τ ∓) : Br(νµ ± τ ∓) : Br(ντ ± τ ∓), respectively. The information on the couplings λ ′ i can be drawn by measuring Br(litb) ∝ |λ ′ i | 2 if the neutralino LSP is heavier than the top quark.