Production Of Gauginos Research Articles

Search for electroweak production of charginos and neutralinos in WH events in proton-proton collisions at sqrt{s}=13 TeV

Results are reported from a search for physics beyond the standard model in proton-proton collision events with a charged lepton (electron or muon), two jets identified as originating from a bottom quark decay, and significant imbalance in the transverse momentum. The search was performed using a data sample corresponding to 35.9 fb−1, collected by the CMS experiment in 2016 at sqrt{s}=13 TeV. Events with this signature can arise, for example, from the electroweak production of gauginos, which are predicted in models based on supersymmetry. The event yields observed in data are consistent with the estimated standard model backgrounds. Limits are obtained on the cross sections for chargino-neutralino left({tilde{chi}}_1^{pm }{tilde{chi}}_2^0right) production in a simplified model of supersymmetry with the decays {chi}_1^{pm}to {mathrm{W}}^{pm }{tilde{chi}}_1^0kern0.5em mathrm{and}kern0.5em {tilde{chi}}_2^0to mathrm{H}{chi}_1^0 . Values of {m}_{{tilde{chi}}_1^{pm }} between 220 and 490 GeV are excluded at 95% confidence level by this search when the {tilde{chi}}_1^0 is massless, and values of {m}_{{tilde{chi}}_1^0} are 1 excluded up to 110 GeV for {m}_{{tilde{chi}}_1^{pm }}approx 450 GeV.

Soft gluon resummation for associated gluino-gaugino production at the LHC

We perform a threshold resummation calculation for the associated production of gluinos and gauginos at the LHC to the next-to-leading logarithmic accuracy. Analytical results are presented for the process-dependent soft anomalous dimension and the hard function. The resummed results are matched to a full next-to-leading order calculation, for which we have generalised the previously known results to the case of supersymmetric scenarios featuring non-universal squark masses. Numerically, the next-to-leading logarithmic contributions increase the total next-to-leading order cross section by 7 to 20% for central scale choices and gluino masses of 3 to 6 TeV, respectively, and reduce its scale dependence typically from up to $\pm12$% to below $\pm3$%.

Precision predictions for direct gaugino and slepton production at the LHC

The search for electroweak superpartners has recently moved to the centre of interest at the LHC. We provide the currently most precise theoretical predictions for these particles, use them to assess the precision of parton shower simulations, and reanalyse public experimental results assuming more general decompositions of gauginos and sleptons.

Searches for electroweak production of supersymmetric gauginos and sleptons with the ATLAS detector

Results from the searches for electroweak production of gauginos or sleptons decaying into leptonic final states performed using 20.3 fb−1 of proton-proton collision data at √S = 8 TeV recorded with the ATLAS experiment at the Large Hadron Collider are presented. No significant excesses are observed with respect to the prediction from Standard Model processes. Limits are set on a wide range of SUSY models.

Searches for electroweak production of supersymmetric gauginos and sleptons with the ATLAS detector

Searches for electroweak production of supersymmetric gauginos and sleptons with the ATLAS detector

Searches for electroweak production of supersymmetric gauginos and sleptons with the ATLAS detector

Searches for electroweak production of supersymmetric gauginos and sleptons with the ATLAS detector

Searches for Supersymmetry and Exotics phenomena with the ATLAS detector

Searches for new physics beyond the Standard Model are performed using the p-p LHC data collected with the ATLAS detector in 2011 at 7 TeV and in 2012 at 8 TeV centre-of-mass energy. Various production modes for supersymmetric (SUSY) particles are considered: strong production of squarks and gluinos, weak production of sleptons and gauginos, R-parity violating decays and long-lived particles. No significant deviation from the Standard Model processes is observed and limits are set on different flavours of SUSY, such as cMSSM/mSUGRA, pMSSM, GMSB and AMSB. Searches for exotic models for BSM physics are performed, probing for a large variety of well-motivated models, such as heavy gauge resonances, excited fermions, extra-dimensions, exotic Higgs models and new quarks. As in the case of SUSY searches, no excess is observed above the SM background and limits are obtained for the models mentioned above.

Search for supersymmetry with like-sign lepton-tau events at CDF.

We present a search for chargino-neutralino associated production using like electric charge dilepton events collected by the CDF II detector at the Fermilab Tevatron in proton-antiproton collisions at sqrt[s] = 1.96 TeV. One lepton is identified as the hadronic decay of a tau lepton, while the other is an electron or muon. In data corresponding to 6.0 fb(-1) of integrated luminosity, we obtain good agreement with standard model predictions and set limits on the chargino-neutralino production cross section for simplified gravity- and gauge-mediated models. As an example, assuming that the chargino and neutralino decays to taus dominate, in the simplified gauge-mediated model we exclude cross sections greater than 300 fb at 95% credibility level for chargino and neutralino masses of 225 GeV/c(2). This analysis is the first to extend the LHC searches for electroweak supersymmetric production of gauginos to high tanβ and slepton next-to-lightest supersymmetric particle scenarios.

Searches for direct supersymmetric gaugino and slepton pair production in final states with leptons with the ATLAS detector

A search for direct production of supersymmetric gauginos and sleptons in final states with two and three leptons is presented. The two lepton analysis uses 4.7 fb(-1) of proton-proton collision data at root s = 7 TeV, while the three lepton analysis uses 13 fb(-1) at root s = 8 TeV. All data were recorded by the ATLAS detector at the Large Hadron Collider. The results are interpreted in the phenomenological minimal supersymmetric Standard Model, as well as simplified models. No significant excess above the Standard Model expectation is observed. Limits on the particle masses are placed at the 95% confidence level. In simplified models, chargino masses are excluded up to 580 GeV.

Searches with multilepton final states

In this talk, the latest results from CMS and ATLAS on searches for new physics with multiple leptons in the final state are presented using up to 20/fb of data from the 8 TeV LHC run of 2012. Interpretation of results in terms of SUSY searches for production of gauginos and sleptons are shown. For RP conserving models, both neutralinos and gravitinos as lightest supersymmetric particles are considered.

SUSY searches for EWK production of Gauginos and Sleptons at the LHC by CMS

We search for signs of new physics in events with multi-leptonic final states in 9.2 fb −1 of protonproton collisions at √ s = 8 TeV with the CMS experiment [1]. The final states under study comprise exactly three leptons, four leptons, a pair of same-sign leptons, two opposite-sign-same-flavor leptons plus jets, and two opposite- sign leptons which have a mass outside the Z-boson decay window. Observations agree well with the expectations from the standard model. The obtained results are then interpreted as limits on the direct electroweak SUSY production of charginos, neutralinos and sleptons.

Search for direct slepton and gaugino production in final states with two leptons and missing transverse momentum with the ATLAS detector in pp collisions at [formula omitted

A search for the electroweak pair production of charged sleptons and weak gauginos decaying into final states with two leptons is performed using 4.7 fb−1 of proton–proton collision data at s=7 TeV recorded with the ATLAS experiment at the Large Hadron Collider. No significant excesses are observed with respect to the prediction from Standard Model processes. In the scenario of direct slepton production, if the sleptons decay directly into the lightest neutralino, left-handed slepton masses between 85 and 195 GeV are excluded at 95% confidence level for a 20 GeV neutralino. Chargino masses between 110 and 340 GeV are excluded in the scenario of direct production of wino-like chargino pairs decaying into the lightest neutralino via an intermediate on-shell charged slepton for a 10 GeV neutralino. The results are also interpreted in the framework of the phenomenological minimal supersymmetric Standard Model.

Gaugino production in proton-proton collisions at a center-of-mass energy of 8 TeV

Abstract Motivated by hints for a light Standard Model-like Higgs boson and a shift in experimental attention towards electroweak supersymmetry particle production at the CERN LHC, we update in this paper our precision predictions at next-to-leading order of perturbative QCD matched to resummation at the next-to-leading logarithmic accuracy for direct gaugino pair production in proton-proton collisions with a center-of-mass energy of 8 TeV. Tables of total cross sections are presented together with the corresponding scale and parton density uncertainties for benchmark points adopted recently by the experimental collaborations, and figures are presented for up-to-date model lines attached to them. Since the experimental analyses are currently obtained with parton showers matched to multi-parton matrix elements, we also analyze the precision of this procedure by comparing invariant-mass and transverse-momentum distributions obtained in this way to those obtained with threshold and transverse-momentum resummation.

Searches for supersymmetry with the ATLAS detector using final states with two leptons and missing transverse momentum in [formula omitted] proton–proton collisions

Results of three searches are presented for the production of supersymmetric particles decaying into final states with missing transverse momentum and exactly two isolated leptons, e or μ. The analysis uses a data sample collected during the first half of 2011 that corresponds to a total integrated luminosity of 1 fb−1 of s=7 TeV proton–proton collisions recorded with the ATLAS detector at the Large Hadron Collider. Opposite-sign and same-sign dilepton events are separately studied, with no deviations from the Standard Model expectation observed. Additionally, in opposite-sign events, a search is made for an excess of same-flavour over different-flavour lepton pairs. Effective production cross sections in excess of 9.9 fb for opposite-sign events containing supersymmetric particles with missing transverse momentum greater than 250 GeV are excluded at 95% CL. For same-sign events containing supersymmetric particles with missing transverse momentum greater than 100 GeV, effective production cross sections in excess of 14.8 fb are excluded at 95% CL. The latter limit is interpreted in a simplified electroweak gaugino production model excluding chargino masses up to 200 GeV, under the assumption that slepton decay is dominant.

Flavour violation in gauge-mediated supersymmetry breaking models: Experimental constraints and phenomenology at the LHC

We present an extensive analysis of gauge-mediated supersymmetry breaking models with minimal and non-minimal flavour violation. We first demonstrate that low-energy, precision electroweak, and cosmological constraints exclude large “collider-friendly” regions of the minimal parameter space. We then discuss various possibilities how flavour violation, although naturally suppressed, may still occur in gauge-mediation models. The introduction of non-minimal flavour violation at the electroweak scale is shown to relax the stringent experimental constraints, so that benchmark points, that are also cosmologically viable, can be defined and their phenomenology, i.e. squark and gaugino production cross sections with flavour violation, at the LHC can be studied.

Erratum: Next-to-leading order supersymmetric QCD predictions for associated production of gauginos and gluinos [Phys. Rev. D62, 095014 (2000)

We present complete results of a next-to-leading order calculation of the production of gaugino-like charginos ($\chargino$) and neutralinos ($\neutralino$) in association with gluinos ($\gluino$) at hadron colliders, including the strong corrections from the exchange of colored particles and sparticles. Adopting a variety of models for the sparticle mass spectrum, including typical supergravity (SUGRA) models and a light gluino model, we provide predictions for total and differential cross sections at the energies of the Fermilab Tevatron and CERN Large Hadron Collider (LHC).

Associated production of sfermions and gauginos at high-energy ee colliders

In the context of the Minimal Supersymmetric extension of the Standard Model, we analyze the production at future high-energy $e^+e^-$ colliders of second and third generation scalar leptons as well as scalar quarks in association with neutralinos and charginos, $e^+e^-\to f\tilde{f}\chi$. In the case of third generation squarks, we also discuss the associated production with gluinos. We show that the cross sections for some of these three-body final state processes could be significant enough to allow for the detection of scalar fermions with masses above the kinematical two--body threshold, $\sqrt{s}= 2m_{\tilde{f}}$. We then discuss, taking as a reference example the case of scalar muons, the production cross sections in various approximations and make a comparison with the full four-body production process, $e^+e^- \to f\bar{f} \chi \chi$, in particular around the two-sfermion threshold.

Associated production of sfermions and gauginos at high-energy ee colliders: The case of selectrons and electronic sneutrinos

We analyze the associated production at future high--energy $e^+e^-$ colliders, of first generation sleptons with neutralinos and charginos in the modes $e^+ e^-$ and $e \gamma$, in the framework of the Minimal Supersymmetric extension of the Standard Model. We show that the production rates, in particular for associated production of right--handed selectrons and the lightest neutralino which in general is the first accessible kinematically, can be much larger than the corresponding ones for second and third generation scalar leptons and for scalar quarks. With the high--luminosities expected at these colliders, the detection of first generation sleptons with masses significantly above the kinematical two--body threshold, $\sqrt{s}= 2m_{\tilde{l}}$, is thus possible in favourable regions of the parameter space.

Search for R-parity violation with a [formula omitted] coupling at [formula omitted] GeV

Searches for pair production of gauginos and squarks in e + e − collisions at a centre-of-mass energy of 189 GeV have been performed on data corresponding to an integrated luminosity of 158 pb −1 collected by the DELPHI detector at LEP. The data were analyzed under the assumption of non-conservation of R-parity through a single dominant U ̄ D ̄ D ̄ coupling between squarks and quarks. Typical final states contain between 4 and 10 jets with or without additional leptons. No excess of data above Standard Model expectations was observed. The results were used to constrain domains of the MSSM parameter space and derive limits on the masses of supersymmetric particles. The following mass limits at 95% CL were obtained from these searches: neutralino mass: m χ ̃ 0 1 ⩾32 GeV; chargino mass: m χ ̃ + 1 ⩾94 GeV; stop and sbottom mass (indirect decay) with ΔM>5 GeV: m t ̃ 1 ⩾74 GeV for Φ mix=0 rad, m t ̃ 1 ⩾59 GeV for Φ mix=0.98 rad, m b ̃ 1 ⩾72 GeV for Φ mix=0 rad. The angle φ mix is the mixing angle between left and right handed quarks.

Next-to-leading order supersymmetric QCD predictions for associated production of gauginos and gluinos

We present complete results of a next-to-leading order calculation of the production of gaugino-like charginos ({tilde {chi}}{sup {+-}}) and neutralinos ({tilde {chi}}{sup 0}) in association with gluinos ({tilde g}) at hadron colliders, including the strong corrections from the exchange of colored particles and sparticles. Adopting a variety of models for the sparticle mass spectrum, including typical supergravity (SUGRA) models and a light gluino model, we provide predictions for total and differential cross sections at the energies of the Fermilab Tevatron and CERN Large Hadron Collider (LHC).