Physics at the Large Hadron Collider (LHC) and the International
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Linear Collider (ILC) will be complementary in many respects, as has been demonstrated at previous generations of hadron and ...lepton colliders. This report addresses the possible interplay between the LHC and ILC in testing the Standard Model and in discovering and determining the origin of new physics. Mutual benefits for the physics programme at both machines can occur both at the level of a combined interpretation of Hadron Collider and Linear Collider data and at the level of combined analyses of the data, where results obtained at one machine can directly influence the way analyses are carried out at the other machine. Topics under study comprise the physics of weak and strong electroweak symmetry breaking, supersymmetric models, new gauge theories, models with extra dimensions, and electroweak and QCD precision physics. The status of the work that has been carried out within the LHC/ILC Study Group so far is summarized in this report. Possible topics for future studies are outlined.
Searches for physics beyond the Standard Model of particle physics are about to enter a new era with the startup of the Large Hadron Collider (LHC) at CERN. Prospects for R-parity conserving ...supersymmetry discovery and measurements with the ATLAS detector at the LHC are presented. Methods for determining the parameters of the underlying supersymmetry model and the relation to dark matter estimation are discussed.
It is argued that mass anomalies at the N≈Z line are associated with SU(4) isospin-spin symmetry. Drawing on these arguments, a Weizsäcker-type nuclear mass formula is investigated which has the ...eigenvalue of the quadratic Casimir operator of SU(4) as a Wigner term. This SU(4)-based mass formula yields a better agreement than the one with the usual Wigner term |N—Z|/A. In addition, the SU(4) eigenvalue expression adequately replaces the usual pairing term of the Weizsäcker formula giving a lower overall rms deviation than the latter.
If supersymmetric particles are produced at the Large Hadron Collider it
becomes very important not only to identify them, but also to determine their
masses with the highest possible precision, ...since this may lead to an
understanding of the SUSY-breaking mechanism and the physics at some higher
scale. We here report on studies of how such mass measurements are obtained,
and how the precision can be optimized.
ECONF C050318:0211,2005 The measurements of kinematical endpoints, in cascade decays of
supersymmetric particles, in principle allow for a determination of the masses
of the unstable particles. ...However, in this procedure ambiguities often arise.
We here illustrate how such ambiguities arise. They can be resolved by a
precise determination of the LSP mass, provided by the Linear Collider.
JHEP 0506:015,2005 If R-parity conserving supersymmetry is realised with masses below the TeV
scale, sparticles will be produced and decay in cascades at the LHC. In the
case of a neutral LSP, which ...will not be detected, decay chains cannot be fully
reconstructed, complicating the mass determination of the new particles. In
this paper we extend the method of obtaining masses from kinematical endpoints
to include a gluino at the head of a five-sparticle decay chain. This
represents a non-trivial extension of the corresponding method for the squark
decay chain. We calculate the endpoints of the new distributions and assess
their applicability by examining the theoretical distributions for a variety of
mass scenarios. The precision with which the gluino mass can be determined by
this method is investigated for the mSUGRA point SPS 1a. Finally we estimate
the improvement obtained from adding a Linear Collider measurement of the LSP
mass.
JHEP 0412:003,2004 If R-parity conserving supersymmetry exists below the TeV-scale, new
particles will be produced and decay in cascades at the LHC. The lightest
supersymmetric particle will escape ...the detectors, thereby complicating the
full reconstruction of the decay chains. In this paper we expand on existing
methods for determining the masses of the particles in the cascade from
endpoints of kinematical distributions. We perform scans in the mSUGRA
parameter space to delimit the region where this method is applicable. From the
examination of theoretical distributions for a wide selection of mass scenarios
it is found that caution must be exerted when equating the theoretical
endpoints with the experimentally obtainable ones. We provide analytic formulae
for the masses in terms of the endpoints most readily available. Complications
due to the composite nature of the endpoint expressions are discussed in
relation to the detailed analysis of two points on the SPS~1a line. Finally we
demonstrate how a Linear Collider measurement can improve dramatically on the
precision of the masses obtained.
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