[en] We study BPS saturated objects with axial geometry (wall junctions, vortices) in generalized Wess-Zumino models. It is observed that the tension of such objects is negative in general (although ''exceptional'' models are possible). We show how an ambiguity in the definition of central charges does not affect physical quantities, and we comment on the stability of the junctions and vortices. We illustrate these issues in two classes of models with Z_N symmetry. On the basis of analytical large N calculations and numerical calculations at finite N, we argue that the domain wall junctions in these models are indeed BPS saturated, and we calculate the junction tensions explicitly. (c) 2000 The American Physical Society

[en] Assuming that the axion mechanism of solving the strong CP problem does not exist and the vanishing of θ at the tree level is achieved by some model-building means, we study the naturalness of having large CP-violating sources in the leptonic sector. We consider the radiative mechanisms which transfer a possibly large CP-violating phase in the leptonic sector to the θ parameter. It is found that a large θ cannot be induced in the models with one Higgs doublet as at least three loops are required in this case. In the models with two or more Higgs doublets the dominant source of θ is the phases in the scalar potential, induced by CP violation in the leptonic sector. Thus, in the minimal supersymmetric standard model framework the imaginary part of the trilinear soft-breaking parameter A_l generates the corrections to the theta angle already at one loop. These corrections are large, excluding the possibility of large phases, unless the universality in the slepton sector is strongly violated. (c) 2000 The American Physical Society

[en] We develop an efficient technique to compute anomalies in supersymmetric theories by combining the so-called nonlocal regularization method and superspace techniques. To illustrate the method we apply it to a four-dimensional toy model with potentially anomalous N=1 supersymmetry and prove explicitly that in this model all the candidate supersymmetry anomalies have vanishing coefficients at the one-loop level. copyright 1997 The American Physical Society

[en] R-parity conservation is an ad hoc assumption in the most popular version of the supersymmetric standard model. Most studies of models which do allow for R-parity violation have been restricted to various limiting scenarios. The single-VEV parametrization used in this paper provides a workable framework to analyze phenomenology of the most general theory of SUSY without R parity. We perform a comprehensive study of leptonic phenomenology at the tree level. Experimental constraints on various processes are studied individually and then combined to yield regions of admissible parameter space. In particular, we show that large R-parity violating bilinear couplings are not ruled out, especially for large tan β. (c) 2000 The American Physical Society

[en] We make a detailed study of the unification of gauge couplings in the MSSM with large extra dimensions. We find some scenarios where unification can be achieved [with α₃(M_Z) within 1σ of the experimental value] with both the compactification scale and the SUSY breaking scale in the few TeV range. No enlargement of the gauge group or particle content is needed. One particularly interesting scenario is when the SUSY breaking scale is larger than the compactification scale, but both are small enough to be probed at the CERN LHC. Unification in two scale compactification scenarios is also investigated and found to give results within the LHC reach. (c) 2000 The American Physical Society

[en] Short communication

[en] We discuss the relic density of the lightest of the supersymmetric particles in view of new cosmological data, which favor the concept of an accelerating universe with a nonvanishing cosmological constant. Recent astrophysical observations provide us with very precise values of the relevant cosmological parameters. Certain of these parameters have direct implications on particle physics, e.g., the value of matter density, which in conjunction with electroweak precision data put severe constraints on the supersymmetry breaking scale. In the context of the constrained minimal supersymmetric standard model (CMSSM) such limits read as M_1/2≅300 GeV-340 GeV, m₀≅80 GeV-130 GeV. Within the context of the CMSSM a way to avoid these constraints is either to go to the large tan β and μ>0 region, or make τ(tilde sign)_R, the next to lightest supersymmetric particle (LSP), be almost degenerate in mass with the LSP. (c) 2000 The American Physical Society

[en] A striking consequence of supersymmetry breaking communicated purely via the superconformal anomaly is that the gaugino masses are proportional to the gauge β functions. This result, however, is not unique to anomaly mediation. We present examples of ''generalized'' gauge-mediated models with messengers in standard model representations that give nearly identical predictions for the gaugino masses, but positive (mass)² for all sleptons. There are remarkable similarities between an anomaly-mediated model with a small additional universal mass added to all scalars and the gauge-mediated models with a long-lived W-ino next-to-lightest supersymmetric particle, leading to only a small set of observables that provide robust distinguishing criteria. These include ratios of the heaviest to lightest selectrons, smuons, and top squarks. The sign of the gluino soft mass is an unambiguous distinction, but requires measuring a difficult class of one-loop radiative corrections to sparticle interactions. A high precision measurement of the Higgs-boson-b-b(bar sign) coupling is probably the most promising interaction from which this sign might be extracted. (c) 2000 The American Physical Society

[en] We consider supersymmetric Yang-Mills theory on RxS¹xS¹. In particular, we choose one of the compact directions to be light like and another to be space like. Since the SDLCQ regularization explicitly preserves supersymmetry, this theory is totally finite, and thus we can solve for bound state wave functions and masses numerically without renormalizing. We present the masses as functions of the longitudinal and transverse resolutions and show that the masses converge rapidly in both resolutions. We also study the behavior of the spectrum as a function of the coupling and find that at strong coupling there is a stable, well-defined spectrum which we present. We also find several unphysical states that decouple at large transverse resolution. There are two sets of massless states; one set is massless only at zero coupling and the other is massless at all couplings. Together these sets of massless states are in one-to-one correspondence with the full spectrum of the dimensionally reduced theory. (c) 2000 The American Physical Society

[en] We study various modifications to the minimal models of gauge-mediated supersymmetry breaking. We argue that, under reasonable assumptions, the structure of the messenger sector is rather restricted. We investigate the effects of possible mixing between messenger and ordinary squark and slepton fields and, in particular, violation of universality. We show that acceptable values for the μ and B parameters can naturally arise from discrete, possibly horizontal, symmetries. We claim that in models where the supersymmetry-breaking parameters A and B vanish at the tree level, tanβ could be large without fine-tuning. We explain how the supersymmetric CP problem is solved in such models. copyright 1997 The American Physical Society