R-parity violation in production at LHC and Tevatron

2000

We study the production of (t +t)g at the hadron colliders in an R-parity (R p) violating supersymmetric model. This process provides us with information not only about R p violation, but may also help us in detecting the supersymmetry itself. It is possible to detect an R p violating signal (with single gluino production) at the future hadron colliders, such as Fermilab Tevatron Run II or CERN Large Hadron Collider (LHC), if the parameters in the supersymmetric / R p interactions are not too small, e.g. for mg = 1 TeV, λ = 0.1, still hundreds of events are produced at LHC with luminosity 30 f b −1. Even if we could not detect a signal of / R p in the experiment, we get stringent constraints on the heavy flavour / R p couplings. In addition to the minimal supersymmetric standard model we have also considered some models with a heavy gluino as the lightest supersymmetric particle.

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.

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.

Physics Letters B, 2014

We discuss the possible signatures at the Large Hadron Collider in models where R-parity is spontaneously broken. In the context of the minimal gauge theory for R-parity, we investigate signals with multileptons which can provide an unique test of this theory. The possible impact of these ideas for the search of supersymmetry at the Large Hadron Collider is discussed. We also discuss the constraints coming from cosmology due to the existence of two light sterile neutrinos in the theory.

Physical Review D, 1997

We discuss single top quark production via u idj → tb at the Fermilab Tevatron in the minimal supersymmetric model with R-parity violation. We find that within the allowed range of coupling constants, the lepton-number violating couplings can give rise to observable effects when the slepton mass lies in a specific narrow range. For the baryon-number violating couplings, the contribution to the production rate can be quite large in the presently allowed range of the coupling constants. We show that the measurement of single top production at the upgraded Tevatron can be used to constrain a linear combination of products of the R-parity violating couplings.

Journal of High Energy Physics, 2012

We investigate the simplest gauge theory for spontaneous R-parity breaking and its testability at the LHC. This theory based on a local B-L gauge symmetry can be considered as the simplest framework for understanding the origin of the R-parity violating interactions, giving rise to potential lepton number violating signals and suppressed baryon number violating operators. The full spectrum of the theory and the constraints coming from neutrino masses are analyzed in great detail. We discuss the proton decay issue and the possible dark matter candidates. In order to assess the testability of the theory we study the properties of the new gauge boson, the neutralino decays and the main production channels for the charged sleptons at the LHC. We find that the channels with four charged leptons, three of them with the same sign, and four jets give us the most striking signals for the testability of lepton number violation at the LHC.

Physical Review D, 2002

We investigate in detail the effects of the R-parity lepton number violation in the minimal supersymmetric standard model (MSSM) on the parent process pp → e + e − +X at the CERN Large Hadron Collider (LHC). The numerical comparisons between the contributions of the R-parity violating effects to the parent process via the Drell-Yan subprocess and the gluongluon fusion are made. We find that the R-violating effects on e + e − pair production at the LHC could be significant. The results show that the cross section of the e + e − pair productions via gluon-gluon collision at the LHC can be of the order of 10 2 fb, and this subprocess maybe competitive with the production mechanism via the Drell-Yan subprocess. We give also quantitatively the analysis of the effects from both the mass of sneutrino and coupling strength of the R-parity violating interactions.

Physics Letters B, 2006

A search for gaugino pair production with a trilepton signature in the framework of R-parity violating supersymmetry via the couplings λ, λ, or λ is presented. The data, corresponding to an integrated luminosity of L≈360 pb, were collected from April 2002 to August 2004 with the D∅ detector at the Fermilab Tevatron Collider, at a center-of-mass energy of s=1.96 TeV. This analysis considers final states with three charged leptons with the flavor combinations eeℓ, μμℓ, and eeτ (ℓ=e or μ). No evidence for supersymmetry is found and limits at the 95% confidence level are set on the gaugino pair production cross section and lower bounds on the masses of the lightest neutralino and chargino are derived in two supersymmetric models.

Physics Letters B, 1997

We study tt production in R-parity violating supersymmetry. The annihilation channel qq → tt gets new contributions from t-channel exchange of squarks or sleptons. With the data from Tevatron on tt production, we find that the squark-or slepton-exchange processes constrain the B-violating λ ′′ couplings or the L-violating λ ′ couplings, respectively. Our bounds are already comparable to the few existing constraints on third-generation R-parity violating couplings, and will improve when more precise measurements of the tt production cross-section become available. We also discuss the effects of these couplings for top production at the LHC.

Physics Letters B, 2006

Search for R-parity violating supersymmetry via the LLĒ couplings λ 121 , λ 122 or λ 133 in pp collisions at √ s = 1.96 TeV