Sphenomenology --- An Overview, with a Focus on a Higgsino LSP World, and on Eventual Tests of String Theory

In this talk, as requested, I begin with a overview and with some basic reminders about how evidence for supersymmetry in nature might appear -- in particular, how SUSY signatures are never clear so it is difficult to search for them without major theoretical input. Models can be usefully categorized phenomenologically by naming their LSP -- that is, once the LSP is approximately fixed so is the behavior of the observables, and the resulting behavior is generally very different for different LSPs. Next I compare the three main LSP-models (gravitino, bino, higgsino). Hints from data suggest taking the higgsino-LSP world very seriously, so I focus on it, and describe its successful prediction of reported events from the 1996 LEP runs. SUSY signatures in the $\tilde h$ LSP world are very different from those that are usually studied. Then I briefly discuss how to measure the parameters of the effective Lagrangian from collider and decay data. Finally I turn to how data will test and help extract the implications of string theories.Comment: Uses espcrc2.st

Extracting GMSB Parameters at a Linear Collider

Assuming gauge-mediated supersymmetry breaking, we simulate precision measurements of fundamental parameters at a 500 GeV e+e- linear collider in the scenario where a neutralino is the next-to-lightest supersymmetric particle. Information on the supersymmetry breaking and the messenger sectors of the theory is extracted from realistic fits to the measured mass spectrum of the Minimal Supersymmetric Model particles and the next-to-lightest supersymmetric particle lifetime.Comment: 6 pages, LaTeX + epsf.sty, 3 figure

Measuring Gauge-Mediated SuperSymmetry Breaking Parameters at a 500 GeV e+e- Linear Collider

We consider the phenomenology of a class of gauge-mediated supersymmetry (SUSY) breaking (GMSB) models at a e+e- Linear Collider (LC) with c.o.m. energy up to 500 GeV. In particular, we refer to a high-luminosity (L ~ 3 x 10^34 cm^-2 s^-1) machine, and use detailed simulation tools for a proposed detector. Among the GMSB-model building options, we define a simple framework and outline its predictions at the LC, under the assumption that no SUSY signal is detected at LEP or Tevatron. Our focus is on the case where a neutralino (N1) is the next-to-lightest SUSY particle (NLSP), for which we determine the relevant regions of the GMSB parameter space. Many observables are calculated and discussed, including production cross sections, NLSP decay widths, branching ratios and distributions, for dominant and rare channels. We sketch how to extract the messenger and electroweak scale model parameters from a spectrum measured via, e.g. threshold-scanning techniques. Several experimental methods to measure the NLSP mass and lifetime are proposed and simulated in detail. We show that these methods can cover most of the lifetime range allowed by perturbativity requirements and suggested by cosmology in GMSB models. Also, they are relevant for any general low-energy SUSY breaking scenario. Values of c*tau_N1 as short as 10's of microns and as long as 10's of metres can be measured with errors at the level of 10% or better after one year of LC running with high luminosity. We discuss how to determine a narrow range (<~ 5%) for the fundamental SUSY breaking scale sqrt(F), based on the measured m_N1, c*tau_N1. Finally, we suggest how to optimise the LC detector performance for this purpose.Comment: 56 pages, 32 figures (48 eps files), LaTeX + epsf.sty + colordvi.sty. Revision v2: minor changes/additions, version to be published in EPJ

Precision GMSB at a Linear Collider

We simulate precision measurements of gauge-mediated supersymmetry breaking (GMSB) parameters at a 500 GeV e+e- linear collider in the scenario where a neutralino is the next-to-lightest supersymmetric particle. Information on the supersymmetry breaking and the messenger sectors of the theory is extracted from the measured sparticle mass spectrum and neutralino lifetime.Comment: LaTeX + sprocl.sty + epsf.sty, 6 pages, 3 figures (5 eps files

Tau Polarizations in the Three-body Slepton Decays with Stau as the NLSP

In the gauge-mediated supersymmetry breaking models with scalar tau as the next-to-lightest supersymmetric particle, a scalar lepton may decay dominantly into its superpartner, tau lepton, and the lightest scalar tau particle. We give detailed formulas for the three-body decay amplitudes and the polarization asymmetry of the outgoing tau lepton . We find that the tau polarizations are sensitive to the model parameters such as the stau mixing angle, the neutralino to slepton mass ratio and the neutralino mixing effect.Comment: 13 pages, 5 figures, RevTe

Can the sneutrino be the lightest supersymmetric particle ?

Within the framework of the constrained Minimal Supersymmetric extension of the Standard Model we show that recent LEP I limits on the invisible Z width exclude the possibility that the lightest sparticle is the sneutrino

Determining the Mass for a Light Gravitino

Gauge mediated supersymmetry breaking scenarios with an ultra-light gravitino of mass m_{3/2}=1-10 eV are very interesting, since there is no cosmological gravitino problem. We propose a new experimental determination of the gravitino mass for such an ultra-light gravitino, by measuring a branching ratio of two decay modes of sleptons.Comment: 9 pages, 12 figure

Signals for gauge-mediated supersymmetry breaking models at the CERN LEP2 collider

We consider a general class of models with gauge-mediated supersymmetry breaking in which the gravitino is the lightest supersymmetric particle. Several qualitatively different scenarios arise for the phenomenology of such models, depending on which superpartner(s) decay dominantly to the gravitino. At LEP2, neutralino pair production and slepton pair production can lead to a variety of promising discovery signals, which we systematically study. We investigate the impact of backgrounds for these signals and show how they can be reduced, and outline the effects of model parameter variations on the discovery potential.Comment: 36 pages, LaTeX, 10 figures embedded using epsf.sty (published version; minor changes in wording

Constitutional reforms, fiscal decentralization and regional fiscal flows in Italy

In the last 15 years, Italy has been involved in a complex, confuse and unfinished process of fiscal decentralization. In this context, data on fiscal flows are continuously produced and thrown in the political arena by several actors, political parties, interest groups and media alike, with little scientific underpinnings and often with limited adherence to reality. This paper discusses at length the issue of fiscal federalism in Italy and presents a careful attempt to measure regional redistribution, or fiscal flows across regions. It describes the decentralization process in Italy from the beginning of the ‘90’s to date and presents a few data on the main features of the Italian decentralization process, that only happened on the financing side, with little effects on the allocation of expenditure responsibility between levels of governments. The focus is however on the measurement of regional fiscal flows and on the problems concerning the regionalization of public expenditure and revenues. Our basic conclusions can be summarised as follows. Fiscal flows in Italy are huge and are mostly driven by the large difference in economic development between the different areas of the country. The public sector generally works in the direction of equalizing per capita (current) public expenditure across regions, at least for fundamental services. However, the distance in economic development, and therefore in tax revenues among regions, is so large that even this partial equalization is enough to generate consistent fiscal flows across the national territory. Clearly, fiscal federalism has some chances of success in Italy only if it works in the direction of reducing the distance between territorial areas and the Italian debate on fiscal federalism, rich in ideology and poor in facts, would certainly benefit by an improved quality of regional data and by official estimations, based on clear and transparent methodology, of regional fiscal flows.fiscal federalism, net fiscal flows, regional redistribution

Measuring the SUSY Breaking Scale at the LHC in the Slepton NLSP Scenario of GMSB Models

We report a study on the measurement of the SUSY breaking scale sqrt(F) in the framework of gauge-mediated supersymmetry breaking (GMSB) models at the LHC. The work is focused on the GMSB scenario where a stau is the next-to-lightest SUSY particle (NLSP) and decays into a gravitino with lifetime c*tau_NLSP in the range 0.5 m to 1 km. We study the identification of long-lived sleptons using the momentum and time of flight measurements in the muon chambers of the ATLAS experiment. A realistic evaluation of the statistical and systematic uncertainties on the measurement of the slepton mass and lifetime is performed, based on a detailed simulation of the detector response. Accessible range and precision on sqrt(F) achievable with a counting method are assessed. Many features of our analysis can be extended to the study of different theoretical frameworks with similar signatures at the LHC.Comment: 28 pages, 12 figures (18 eps files). Revised version v2(published in JHEP): Some important corrections and additions to v