15 research outputs found
NLO electroweak contributions to squark pair production at the LHC
We present the tree-level and next-to-leading order (NLO) electroweak (EW)
contributions to squark-squark production at the Large Hadron Collider (LHC)
within the framework of the Minimal Supersymmetric Standard Model (MSSM).Comment: To appear in the proceedings of 17th International Conference on
Supersymmetry and the Unification of Fundamental Interactions (SUSY09),
Boston, USA, 5-10 Jun 200
Hadronic Production of Colored SUSY Particles with Electroweak NLO Contributions
We consider the production of squarks and gluinos at hadronic colliders. An
overview over the class of processes is given. We investigate in detail the
tree-level and higher order EW contributions to the cross sections. Special
care has to be taken to obtain infrared finite observables. We study
numerically stop--anti-stop and squark--gluino production at the LHC.Comment: 3 pages, 2 figures; To appear in the proceedings of 16th
International Conference on Supersymmetry and the Unification of Fundamental
Interactions (SUSY08), Seoul, Korea, 16-21 Jun 200
Testing the Mechanism for the LSP Stability at the LHC
The lightest supersymmetric particle (LSP) is a natural candidate for the
cold dark matter of the universe. In this Letter we discuss how to test the
mechanism responsible for the LSP stability at the LHC. We note that if
R-parity is conserved dynamically one should expect a Higgs boson which decays
mainly into two right-handed neutrinos (a "leptonic" Higgs) or into two
sfermions. The first case could exhibit spectacular lepton number violating
signals with four secondary vertices due to the long-lived nature of
right-handed neutrinos. These signals, together with the standard channels for
the discovery of SUSY, could help to establish the underlying theory at the TeV
scale.Comment: 4 pages, 3 figures, 1 table, minor corrections, published in Physics
Letters
Electroweak contributions to squark--gluino production at the LHC
We calculated the electroweak contributions to the hadronic production of a
squark in association with a gluino within the Minimal Supersymmetric Standard
Model (MSSM). Presented are complete next-to-leading order electroweak (NLO EW)
corrections at O(alpha_s^2 alpha), which include real photon and real quark
radiation processes. Also considered are photon induced tree level O(alpha_s
alpha) contributions.Comment: 23 pages, 15 figure
Hadronic production of squark-squark pairs: The electroweak contributions
We compute the electroweak (EW) contributions to squark--squark pair
production processes at the LHC within the framework of the Minimal
Supersymmetric Standard Model (MSSM). Both tree-level EW contributions, of
O(alpha_s alpha + alpha^2), and next-to-leading order (NLO) EW corrections, of
O(alpha_s^2 alpha), are calculated. Depending on the flavor and chirality of
the produced quarks, many interferences between EW-mediated and QCD-mediated
diagrams give non-zero contributions at tree-level and NLO. We discuss the
computational techniques and present an extensive numerical analysis for
inclusive squark--squark production as well as for subsets and single
processes. While the tree-level EW contributions to the integrated cross
sections can reach the 20% level, the NLO EW corrections typically lower the LO
prediction by a few percent.Comment: 36 pages, 18 figure
Lepton Number Violation from Colored States at the LHC
The possibility to search for lepton number violating signals at the Large
Hadron Collider (LHC) in the colored seesaw scenario is investigated. In this
context the fields that generate neutrino masses at the one-loop level are
scalar and Majorana fermionic color-octets of SU(3). Due to the QCD strong
interaction these states may be produced at the LHC with a favorable rate. We
study the production mechanisms and decays relevant to search for lepton number
violation signals in the channels with same-sign dileptons. In the simplest
case when the two fermionic color-octets are degenerate in mass, one could use
their decays to distinguish between the neutrino spectra. We find that for
fermionic octets with mass up to about 1 TeV the number of same-sign dilepton
events is larger than the standard model background indicating a promising
signal for new physics.Comment: minor corrections, added reference
SUSY QCD corrections to electroweak gauge boson production with an associated jet at the LHC
We study the stability of the neutral- and charged-current Drell-Yan process
in association with a jet as a standard candle at the LHC under the inclusion
of O(alpha_s) supersymmetric QCD (SQCD) corrections within the MSSM. We include
the decay of the electroweak gauge boson into dileptons, i.e. we consider the
production of charged lepton--anti-lepton or lepton-neutrino final states with
one hard jet. We find that the SQCD corrections are negligible for the
integrated cross section. Only at high lepton transverse momentum can they
induce effects of the percent level.Comment: 21 pages, 9 figures, 2 table