212 research outputs found
Electroweakino Searches: A Comparative Study for LHC and ILC (A Snowmass White Paper)
We make a systematic and comparative study for the LHC and ILC for the
electroweakino searches in the Minimal Supersymmetric Standard Model. We adopt
a general bottom-up approach and scan over the parameter regions for all the
three cases of the lightest supersymmetric particle being Bino-, Wino-, and
Higgsino-like. The electroweakino signal from pair production and subsequent
decay to Wh (h to b\bar b) final state may yield a sensitivity of 95% C.L.
exclusion (5sigma discovery) to the mass scale M_2, mu ~ 250-400 GeV (200-250
GeV) at the 14 TeV LHC with an luminosity of 300 fb^{-1}. Combining with all
the other decay channels, the 95% C.L. exclusion (5sigma discovery) may be
extended to M_2, mu ~ 480-700 GeV (320-500 GeV). At the ILC, the
electroweakinos could be readily discovered once the kinematical threshold is
crossed, and their properties could be thoroughly studied.Comment: 12 pages, 3 figure
ILD Benchmark: Search for Extra Scalars Produced in Association with a boson at GeV
We study the prospects for discovering an extra scalar boson at the
International Linear Collider (ILC) based on a full simulation of the
International Large Detector (ILD). In order to provide results in an as
model-independent way as possible, the analysis uses the recoil of the scalar
against a boson decaying into a pair of muons, .
This process serves as a physics benchmark for the ILD detector performance at
GeV, specifically for the muon ID and momentum resolution, as
well as for the identification of initial state radiation photons and their
energy measurement. As final results, the sensitivities for discovering the
extra scalars at 2 level are evaluated in terms of a scale factor
with respect to the Standard Model value of the cross section
for the Higgs--strahlung process. Two detector models, IDR-L and IDR-S, are
considered in the analysis, which differ in radius of the tracking volume,
aspect ratio and strength of the magnetic field. While the two detector models
show a visible difference in the precision of the reconstructed invariant
di-muon mass, no difference is found at the level of the final results.Comment: This work was carried out in the framework of the ILD concept grou
Tuning Pythia8 for future colliders
The majority of Monte-Carlo (MC) simulation campaigns for future
colliders has so far been based on the leading-order (LO) matrix elements
provided by Whizard 1.95, followed by parton shower and hadronization in
Pythia6, using the tune of the OPAL experiment at LEP. In this contribution, we
test and develop the interface between Whizard3 and Pythia8. As a first step,
we simulate the process with LO matrix elements, and
compare three tunes in Pythia8: the standard Pythia8 tune, the OPAL tune and
the ALEPH tune. At stable-hadron level, predictions of charged and neutral
hadron multiplicities of these tunes are compared to LEP data, since they are
strongly relevant to the performance of particle flow algorithms.
The events are used to perform a full detector simulation and reconstruction
of the International Large Detector concept (ILD) as an example for a
particle-flow-optimised detector. At reconstruction level, a comparison of the
jet energy resolution in these tunes is presented. We found good agreement with
previous results that were simulated by Whizard1+Pythia6. In addition, the
preliminary next-to-leading order (NLO) results are also presented. This modern
MC simulation chain, with matched NLO matrix elements in the future, should be
introduced to ILC or other future colliders.Comment: 8 pages, 7 figures, 1 table, LCWS 202
Prospects of measuring the branching fraction of the Higgs boson decaying into muon pairs at the International Linear Collider
The prospects for measuring the branching fraction of
at the International Linear Collider (ILC) have been evaluated based on a full
detector simulation of the International Large Detector (ILD) concept,
considering centre-of-mass energies () of 250 GeV and 500 GeV. For
both cases, the two final states and
have been analyzed. For integrated
luminosities of 2 ab at GeV and 4 ab at
GeV, the combined precision on the branching fraction of is estimated to be 17{\%}. The impact of the transverse
momentum resolution for this analysis is also studied.Comment: 21 pages, 10 figures, 11 tables. This work was carried out in the
framework of the ILD concept grou
Naturalness and light Higgsinos: why ILC is the right machine for SUSY discovery
Radiatively-driven natural supersymmetry, a theoretically and experimentally
well-motivated framework, centers around the predicted existence of four light,
nearly mass-degenerate Higgsinos with mass GeV (not too far
above ). The small mass splittings amongst the higgsinos, typically 4-20
GeV, results in very little visible energy arising from decays of the heavier
higgsinos. Given that other SUSY particles are considerably heavy, this makes
detection challenging at hadron colliders. On the other hand, the clean
environment of an electron-positron collider with
would enable a decisive search of these required higgsinos, and thus either the
discovery or exclusion of natural SUSY. We present a detailed simulation study
of precision measurements of higgsino masses and production cross sections at
= 500 GeV of the proposed International Linear Collider currently
under consideration for construction in Japan. The study is based on a Geant4
simulation of the International Large Detector concept. We examine several
benchmark points just beyond the HL-LHC reach, with four light higgsinos
directly accessible by the ILC, and the mass differences between the lightest
SUSY particle and the heavier states ranging from about 4 to 20 GeV. It can be
shown that their masses and production cross sections can be precisely measured
to approximately 1\% precision or better. These precise measurements allow for
extracting the underlying weak scale SUSY parameters, giving predictions for
the masses of heavier SUSY states. These provide motivation for future
high-energy colliders. Additionally, dark matter properties may be derived.
Evolution of the measured gaugino masses to high energies should allow testing
the hypothesis of gaugino mass unification.Comment: 6 pages, 4 figures; to appear in the proceedings for EPS-HEP2017,
5-12 July 2017, Venice, Ital
Physics Case for the ILC Project: Perspective from Beyond the Standard Model
The International Linear Collider (ILC) has recently proven its technical
maturity with the publication of a Technical Design Report, and there is a
strong interest in Japan to host such a machine. We summarize key aspects of
the Beyond the Standard Model physics case for the ILC in this contribution to
the US High Energy Physics strategy process. On top of the strong guaranteed
physics case in the detailed exploration of the recently discovered Higgs
boson, the top quark and electroweak precision measurements, the ILC will offer
unique opportunities which are complementary to the LHC program of the next
decade. Many of these opportunities have connections to the Cosmic and
Intensity Frontiers, which we comment on in detail. We illustrate the general
picture with examples of how our world could turn out to be and what the ILC
would contribute in these cases, with an emphasis on value-added beyond the
LHC. These comprise examples from Supersymmetry including light Higgsinos, a
comprehensive bottom-up coverage of NLSP-LSP combinations for slepton, squark,
chargino and neutralino NLSP, a stau-coannihilation dark matter scenario and
bilinear R-parity violation as explanation for neutrino masses and mixing, as
well as generic WIMP searches and Little Higgs models as non-SUSY examples.Comment: 20 pages, 10 figures. Contributed to Snowmass Community Summer Study
201
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