New Confining N=1 Supersymmetric Gauge Theories

We examine N=1 supersymmetric gauge theories which confine in the presence of a tree-level superpotential. We show the confining spectra which satisfy the 't Hooft anomaly matching conditions and give a simple method to find the confining superpotential. Using this method we fix the confining superpotentials in the simplest cases, and show how these superpotentials are generated by multi-instanton effects in the dual theory. These new type of confining theories may be useful for model building, since the size of the matter content is not restricted by an index constraint. Therefore, one expects that a large variety of new confining spectra can be obtained using such models.Comment: 26 pages, LaTe

Chiral Compactification on a Square

We study quantum field theory in six dimensions with two of them compactified on a square. A simple boundary condition is the identification of two pairs of adjacent sides of the square such that the values of a field at two identified points differ by an arbitrary phase. This allows a chiral fermion content for the four-dimensional theory obtained after integrating over the square. We find that nontrivial solutions for the field equations exist only when the phase is a multiple of \pi/2, so that this compactification turns out to be equivalent to a T^2/Z_4 orbifold associated with toroidal boundary conditions that are either periodic or anti-periodic. The equality of the Lagrangian densities at the identified points in conjunction with six-dimensional Lorentz invariance leads to an exact Z_8\times Z_2 symmetry, where the Z_2 parity ensures the stability of the lightest Kaluza-Klein particle.Comment: 28 pages, latex. References added. Clarifying remarks included in section 2. Minor corrections made in section

The Super-little Higgs

Supersymmetry combined with little-Higgs can render the Higgs vev super-little, providing models of electroweak symmetry breaking free from fine-tunings. We discuss the difficulties that arise in implementing this idea and propose one simple successful model. Thanks to appropriately chosen Higgs representations, D-terms give no tree-level mass term to the Goldstone. The fermion representations are anomaly free, generation independent and embeddable into an SU(6) GUT. A simple mechanism provides the large top quark mass.Comment: Additional mechanism to get a quartic coupling discussed. References adde

Higgsless Electroweak Theory following from the Spherical Geometry

A new formulation of the Electroweak Model with 3-dimensional spherical geometry in the target space is suggested. The free Lagrangian in the spherical field space along with the standard gauge field Lagrangian form the full Higgsless Lagrangian of the model, whose second order terms reproduce the same fields with the same masses as the Standard Electroweak Model. The vector bosons and electron masses are generated automatically, so there is no need in special mechanism.Comment: 6 page

The Minimal Set of Electroweak Precision Parameters

We present a simple method for analyzing the impact of precision electroweak data above and below the Z-peak on flavour-conserving heavy new physics. We find that experiments have probed about ten combinations of new physics effects, which to a good approximation can be condensed into the effective oblique parameters Shat, That, Uhat, V, X, W, Y (we prove positivity constraints W, Y >= 0) and three combinations of quark couplings (including a distinct parameter for the bottom). We apply our method to generic extra Z' vectors.Comment: 22 pages, 3 figure

Gauge-Higgs Unification in Orbifold Models

Six-dimensional orbifold models where the Higgs field is identified with some internal component of a gauge field are considered. We classify all possible T^2/Z_N orbifold constructions based on a SU(3) electroweak gauge symmetry. Depending on the orbifold twist, models with two, one or zero Higgs doublets can be obtained. Models with one Higgs doublet are particularly interesting because they lead to a prediction for the Higgs mass, which is twice the W boson mass at leading order: m_H=2 m_W. The electroweak scale is quadratically sensitive to the cut-off, but only through very specific localized operators. We study in detail the structure of these operators at one loop, and identify a class of models where they do not destabilize the electroweak scale at the leading order. This provides a very promising framework to construct realistic and predictive models of electroweak symmetry breaking.Comment: 27 pages, uses axodraw.sty; v2: version to appear in JHE

MFV SUSY: A Natural Theory for R-Parity Violation

We present an alternative approach to low-energy supersymmetry. Instead of imposing R-parity we apply the minimal flavor violation (MFV) hypothesis to the R-parity violating MSSM. In this framework, which we call MFV SUSY, squarks can be light and the proton long lived without producing missing energy signals at the LHC. Our approach differs from that of Nikolidakis and Smith in that we impose holomorphy on the MFV spurions. The resulting model is highly constrained and R-parity emerges as an accidental approximate symmetry of the low-energy Lagrangian. The size of the small R-parity violating terms is determined by the flavor parameters, and in the absence of neutrino masses there is only one renormalizable R-parity violating interaction: the baryon-number violating $\bar{u}\bar{d}\bar{d}$ superpotential term. Low energy observables (proton decay, dinucleon decay and $n-\bar{n}$ oscillation) pose only mild constraints on the parameter space. LHC phenomenology will depend on whether the LSP is a squark, neutralino, chargino or slepton. If the LSP is a squark it will have prompt decays, explaining the non-observation of events with missing transverse energy at the LHC.Comment: 41 pages, 14 figures; v3: minor corrections, matches published versio

Unity of Supersymmetry Breaking Models

We examine the models with gauge group U(1)^{k-1}\times\prod_{i=1}^k SU(n_i), which are obtained from decomposing the supersymmetry breaking model of Affleck, Dine and Seiberg containing an antisymmetric tensor field. We note that all of these models are distinct vacua of a single SU(N) gauge theory with an adjoint superfield. The dynamics of this model may be analyzed using the duality of Kutasov and Schwimmer and the deconfinement trick of Berkooz. This analysis leads to a simple picture for supersymmetry breaking for k=2, complementing that of previous work. We examine the flat directions of these models, and give straightforward criteria for lifting them, explaining the requisite peculiar form of the superpotential. For all cases with k>2, the duality argument fails to give supersymmetry breaking dynamics, and we identify a class of problematic flat directions, which we term 2m-baryons. We study in some detail the requirements for lifting these directions, and uncover some surprising facts regarding the relationship between R-symmetry and supersymmetry breaking in models with several gauge groups.Comment: harvmac, 40 page

The Inclusive Semileptonic Decay Lepton Spectrum from B→Xeν‾B \to X e \overline{\nu}

In this talk, we review the QCD calculation of the lepton spectrum from inclusive semileptonic $B$ decay. We compare this prediction to that of the ACCMM model. This latter work was done in collaboration with Csaba Csaki.Comment: MIT-CTP-2333, uses LATEX. Invited Talk, Presented at WHEPP-3 Workshop in Madras,India, January, 199