Search for r-parity violating supersymmetry in multilepton final states with the D0 detector

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Results obtained from a search for the trilepton signature {mu}{mu}{ell} (with {ell} = e, or {mu}) are combined with two complementary searches for the trilepton signatures ee{ell} and eer and interpreted in the framework of R-parity violating Supersymmetry. Pairwise, R-parity conserving production of the supersymmetric particles is assumed, followed by R-parity violating decays via an LL{bar E}-operator with one dominant coupling {lambda}{sub 122}. An LL{bar E}-operator couples two weak isospin doublet and one singlet (s)lepton fields and thus violates lepton number conservation. The data, collected with the D0 detector at the Fermilab proton-antiproton collider Tevatron, corresponds to an integrated luminosity ... continued below

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266 pages

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Kaefer, Daniela November 1, 2006.

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Results obtained from a search for the trilepton signature {mu}{mu}{ell} (with {ell} = e, or {mu}) are combined with two complementary searches for the trilepton signatures ee{ell} and eer and interpreted in the framework of R-parity violating Supersymmetry. Pairwise, R-parity conserving production of the supersymmetric particles is assumed, followed by R-parity violating decays via an LL{bar E}-operator with one dominant coupling {lambda}{sub 122}. An LL{bar E}-operator couples two weak isospin doublet and one singlet (s)lepton fields and thus violates lepton number conservation. The data, collected with the D0 detector at the Fermilab proton-antiproton collider Tevatron, corresponds to an integrated luminosity of {integral} L dt = 360 {+-} 23 pb{sup -1}. No evident is observed, while 0.41 {+-} 0.11(stat) {+-} 0.07(sys) events are expected from Standard Model processes. The resulting 95% confidence level cross section limits on new physics producing a {mu}{mu}{ell} signature in the detector are of the order of 0.020 to 0.136 pb. They are interpreted in two different supersymmetry scenarios: the mSUGRA and the MSSM model. The corresponding lower limits on the masses of the lightest neutralino ({tilde {chi}}{sub 1}{sup 0}) and the lightest chargino ({tilde {chi}}{sub 1}{sup {+-}}) in case of the mSUGRA model are found to be in the range of: mSUGRA, {mu} > 0: M({tilde {chi}}{sub 1}{sup 0}) {approx}> 115-128 GeV and M({tilde {chi}}{sub 1}{sup {+-}}) {approx}> 215-241 GeV; mSUGRA, {mu} < 0: ({tilde {chi}}{sub 1}{sup 0}) {approx}> 101-114 GeV and M({tilde {chi}}{sub 1}{sup {+-}}) {approx}> 194-230 GeV, depending on the actual values of the model parameters: m{sub 0}, m{sub 1/2}, A{sub 0}, tan{beta}, and {mu}. The first and second parameters provide the boundary conditions for the masses of the supersymmetric spin-0 and spin-1/2 particles, respectively, while A{sub 0} gives the universal value for the trilinear couplings at the GUT scale. The parameter tan {beta} denotes the ratio of the vacuum expectation values of the two Higgs fields and {mu}, finally, represents the Higgs mixing parameter. In the MSSM scenario the lower bound on the mass of the lightest chargino (for fixed neutralino mass) is found to be in the range of: M({tilde {chi}}{sub 1}{sup {+-}}) {approx}> 205 GeV, for M({tilde {chi}}{sub 1}{sup 0}) = 30 GeV; M({tilde {chi}}{sub 1}{sup {+-}}) {approx}> 232 GeV, for M({tilde {chi}}{sub 1}{sup 0}) = 200 GeV. The parameters of the considered MSSM model are: M{sub 1}, M{sub 2}, M{sub 3}, A{sub 0}, tan {beta}, {mu}, and m{sub A}. The first three parameters define the common masses of the superpartners of the U(1){sub Y}, SU(2){sub L}, and SU(3){sub C} bosons at the electroweak scale, respectively. The following three parameters are identical to those defined in the mSUGRA model above, while m{sub A} denotes the mass of the pseudoscalar Higgs boson, present in the supersymmetric extension of the Standard Model. In addition all sfermion masses are set to 1000 GeV.

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266 pages

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  • Report No.: FERMILAB-THESIS-2006-22
  • Grant Number: AC02-07CH11359
  • DOI: 10.2172/907810 | External Link
  • Office of Scientific & Technical Information Report Number: 907810
  • Archival Resource Key: ark:/67531/metadc890508

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  • November 1, 2006

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  • Sept. 22, 2016, 2:13 a.m.

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  • July 25, 2017, 11:14 a.m.

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Kaefer, Daniela. Search for r-parity violating supersymmetry in multilepton final states with the D0 detector, thesis or dissertation, November 1, 2006; Batavia, Illinois. (digital.library.unt.edu/ark:/67531/metadc890508/: accessed October 16, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.