An accord specifying a unique set of conventions for supersymmetric extensions of the Standard Model together with generic file structures for 1) supersymmetric model specifications and input parameters, 2) electroweak scale supersymmetric mass and coupling spectra, and 3) decay tables is presented, to provide a universal interface between spectrum calculation programs, decay packages, and high energy physics event generators. 1 skands@fnal.gov. See home.fnal.gov/∼skands/slha/ for updates and examples.

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Physics at the Large Hadron Collider (LHC) and the International e + e − 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 / LC Study Group so far is summarised in this report. Possible topics for future studies are outlined.4

We present an updated assessment of the viability of t − b − τ Yukawa coupling unification in supersymmetric models. For the superpotential Higgs mass parameter µ > 0, we find unification to less than 1% is possible, but only for GUT scale scalar mass parameter m 16 ∼ 8 − 20 TeV, and small values of gaugino mass m 1/2 < ∼ 400 GeV. Such models require that a GUT scale mass splitting exists amongst Higgs scalars with m 2 Hu < m 2. Viable solutions lead to a radiatively generated inverted scalar mass hierarchy, with third generation and Higgs scalars being lighter than other sfermions. These models have very heavy sfermions, so that unwanted flavor changing and CP violating SUSY processes are suppressed, but may suffer from some fine-tuning requirements. While the generated spectra satisfy b → sγ and (g − 2) µ constraints, there exists tension with the dark matter relic density unless m 16 < ∼ 3 TeV. These models offer prospects for a SUSY discovery at the Fermilab Tevatron collider via the search for W 1 Z 2 → 3ℓ events, or via gluino pair production. If µ < 0, Yukawa coupling unification to less than 5% can occur for m 16 and m 1/2 > ∼ 1 − 2 TeV. Consistency of negative µ Yukawa unified models with b → sγ, (g − 2) µ , and relic density Ωh 2 all imply very large values of m 1/2 typically greater than about 2.5 TeV, in which case direct detection of sparticles may be a challenge even at the LHC.

We examine the phenomenology of minimal supergravity models, assuming only that the low energy theory has the minimal particle content, that electroweak symmetry is radiatively broken, and that R-parity is essentially conserved. After delineating regions of supergravity parameter space currently excluded by direct particle searches at LEP and the Tevatron, we quantify how this search region will be expanded when LEP II and the Tevatron Main Injector upgrades become operational. We describe how various experimental analyses can be consistently combined within a single framework, resulting in a multi-channel search for supersymmetry, but note that this analysis is sensitive to specific assumptions about physics at the unification scale.Typeset using REVT E X 1 Grand Unified Theories (GUTs) [1] provide an attractive synthesis of all gauge interactions. A striking prediction of these models is that the proton is unstable. While the observed stability of the proton can be understood if the GUT scale M X > ∼ 10 16 GeV, the origin and stability of the tiny ratio M W /M X ∼ 10 −14 remain unexplained. Supersymmetry (SUSY) [2] provides an elegant mechanism for the stability of the hierarchy between the two scales provided that supersymmetric particles are lighter than ∼ 1 TeV. More recently, the realization [3] that the precision measurements of the gauge couplings in experiments at LEP are consistent with the simplest SUSY SU(5) GUT (with M SU SY ∼ 1 TeV) but incompatible with minimal non-SUSY SU(5) has motivated many authors [4] to reexamine the expectations of sparticle masses within the theoretically appealing, and relatively strongly constrained, supergravity (SUGRA) framework. Studies of nucleon decay [5] as well as the collider phenomenology [6] of these models have also appeared.Part of the appeal of these models lies in their economy. The masses and couplings of all the sparticles are fixed in terms of just four additional parameters, renormalized at some ultra-high scale at which the physics is very simple. These parameters may be taken [2] to be the common values of soft SUSY-breaking trilinear and bilinear couplings (A 0 and B 0 ), a common SUSY-breaking scalar mass (m 0 ), and a common SUSY-breaking mass for the gauginos of the unbroken grand unified group (m 1/2 ). For phenomenological analyses, however, masses and couplings renormalized at the weak scale are required. These can be readily obtained from the unification scale parameters using renormalization group (RG) techniques [7]. This RG evolution leads [2] to calculable splittings between the masses of the gluinos and the electroweak gauginos and between the squarks and sleptons. Unlike third generation sfermions, the first two generations of squarks are approximately degenerate, consistent with the absence of flavor-changing neutral currents in the K-meson sector. A particular attraction of this framework is that electroweak gauge symmetry is automatically broken down to electromagnetism when the Higgs doublet masses are evolved down to the wea...