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in the R-parity violating SUSY model at hadron colliders 张仁友 中国科学技术大学
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R=(-1) 2S+L+3B SUSY new parity partially R-parity violation (RPV) i.e. non-simultaneous L and B violation in general super-potential Phenomenology: + neutrino-oscillation + stable Proton + scalar sneutrino resonance production and LFV decay Theoretical Motivation ’
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LFV process @Tevatron/LHC: --- sneutrino resonance effect in e can be experimentally detected sneutrino contribution (s-channel)squark contribution (u-,t-channel) --- s-channel decouple with u-channel
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Two decoupled contributions of sneutrino and squark:
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CompHep + Pythia d of e inclusive Not back-to-back!--- --- Large luminosity at the LHCglupn-gluon fusion subprocess! --- the QCD correction is quite significant in the high PT region! kinematic cuts: Why need NLO QCD corrections?
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Contributions up to O( s ) NLO 1.The Leading Order cross section 2. Virtual O( s ) one-loop corrections 3. Real gluon emission corrections 4. Real light-quark emission corrections 5. Higer order gluon-gluon fusion contribution
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Numerical result Inputs:
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-- K-factor vs sneutrino mass at Tevatron and LHC 1.28~1.79 Tevatron 1.32~1.58 LHC
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-- Distribution of the transverse momentum of positron
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NLO QCD correction CompHep + Pythia d of e inclusive
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-- gluon fusion contribution Large luminosity of soft gluon will contribute to low mass region <1%
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-- Distribution of the electron-muon invariant mass a high threshold cut on electron-muon invariant mass !
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1.The first two generations of sneutrino are much heavier than the third one. In order to simplify calculation, we take following assumptions: 2.Applying a high threshold cut on electron-muon invariant mass. (50 GeV) 3.Applying the naive fixed-width scheme in the sneutrino propagator. (10 GeV) 4. Setting decoupled squark and gluino section. (1 TeV !)
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In our investigating parameter space the K-factors vary in the ranges of [1.182,1.643] and [1.335,1.614] at the Tevatron and the LHC, respectively.
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Uncertainty investigation
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The relative error of K-factor induced by the factorization scale: 0.17%(3.1%) 100 GeV 1.8% (1.3%) 250 GeV 3.0%(0.46%) 500 GeV The relative error of K-factor induced by the PDF: 6.0% (5.8%) 100 GeV 7.8% (5.0%) 250 GeV 14.2%(5.9%) 500 GeV
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-- qT distribution
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Conclusions 1. K -factor to be 1.2 ~ 1.8 at Tevatron and LHC; the main uncertainty comes from pdf. 2. High order gluon fusion should be accounted @LHC. 3. The distribution of the transverse momentum of final e- muon pair by resummating the logarithmically-enhanced terms for soft gluon can be a reference for future experimental analysis.
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