We investigate the hadron collider phenomenology of the Minimal Supersymmetric Standard Model (MSSM) with explicit CP violation for Higgs bosons that can be observed in Standard Model search ...channels:
W/ZH
i(→b
b
̄
)
at the Tevatron, and
gg→
H
i
(→
γγ),
t
t
̄
H
i(→b
b
̄
)
and
WW→
H
i
(→
τ
+
τ
−) at the LHC. Our numerical analysis is based on a benchmark scenario proposed earlier called CPX, which has been designed to showcase the effects of CP violation in the MSSM, and on several variant benchmarks. In most of the CPX parameter space, these hadron colliders will find one of the neutral MSSM Higgs bosons. However, there are small regions of parameter space in which none of the neutral Higgs bosons can be detected in the standard channels at the Tevatron and the LHC. This occurs because the neutral Higgs boson with the largest coupling to
W and
Z bosons decays predominantly into either two lighter Higgs bosons or a Higgs boson and a gauge boson, whilst the lighter Higgs boson has only small couplings to the
W and
Z bosons and the top quark. For other choices of CP-violating parameters, all three neutral Higgs bosons can have significant couplings to
W and
Z bosons, producing overlapping signatures: these may or may not be distinguishable from backgrounds. The existence of these regions of parameters provides a strong motivation for a detailed experimental simulation of these channels.
SPYTHIA is an event level Monte Carlo program which simulates particle production and decay at lepton and hadron colliders in the Minimal Supersymmetric Standard Model (MSSM). It is an extension of ...PYTHIA 5.7, with all of its previous capabilities. This paper is meant to supplement the PYTHIA/JETSET user manual, providing a description of the new particle spectrum, hard scattering processes, and decay modes. Several examples of using the program are provided.
Present limits on the precision of SM predictions for jet energies Paramonov, A.A.; Canelli, F.; D’Onofrio, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2010, Letnik:
622, Številka:
3
Journal Article
Recenzirano
Odprti dostop
We investigate the impact of theoretical uncertainties on the accuracy of measurements involving hadronic jets. The analysis is performed using events with a
Z boson and a single jet observed in
p
p
...¯
collisions at
s
=
1.96
TeV
in 4.6
fb
−1 of data from the Collider Detector at Fermilab (CDF). The transverse momenta (
p
T) of the jet and the boson should balance each other due to momentum conservation in the plane transverse to the direction of the
p and
p
¯
beams. We evaluate the dependence of the measured
p
T-balance on theoretical uncertainties associated with initial and final state radiation, choice of renormalization and factorization scales, parton distribution functions, jet-parton matching, calculations of matrix elements, and parton showering. We find that the uncertainty caused by parton showering at large angles is the largest amongst the listed uncertainties. The proposed method can be re-applied at the LHC experiments to investigate and evaluate the uncertainties on the predicted jet energies. The distributions produced at the CDF environment are intended for comparison to those from modern event generators and new tunes of parton showering.
Neutralino and tau slepton pair production can naturally produce an excess of tau lepton pairs at the current LEP collider energies. We describe the constraints this has on the values of the mass ...parameters in the softly broken Supersymmetric Lagrangian, and consider the consequences for superpartner production at LEP and at the Fermilab Tevatron collider. The pair production of the LSP and a heavier neutralino, followed by a 2-body decay to a tau slepton and tau lepton, is consistent with the present LEP data, predicts a chargino mass below 125 GeV, and provides an interesting Cold Dark Matter component, with
Ωh
2∼0.1
–0.2.
Pythia version 6 represents a merger of the
Pythia 5,
Jetset 7 and
SPythia programs, with many improvements. It can be used to generate high-energy-physics ‘events’, i.e. sets of outgoing particles ...produced in the interactions between two incoming particles. The objective is to provide as accurate as possible a representation of event properties in a wide range of reactions. The underlying physics is not understood well enough to give an exact description; the programs therefore contain a combination of analytical results and various models. The emphasis in this article is on new aspects, but a few words of general introduction are included. Further documentation is available on the web.
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