Search

A method is presented for analyzing pi -N scattering data using phase shifts for the low partial waves and a closed term to represent the effect of all higher partial waves. The closed term is calculated on the basis of the analytic properties of the scattering amplitude in the complex cos B plane. The method is applied to pi /sup +/-p angular distribution and polarization data at 310 Mev and removes ambiguous results obtained in a conventional phase shift analysis when f-wave phase shifts were included. Values for the T = 3/2 pi -N phase shifts at 310 Mev are obtained. (auth)

Motivated by specific connections to dark matter signatures, we study the prospects of observing the presence of a relatively light gluino whose mass is in the range ~(500-900) GeV with a wino-like lightest supersymmetric particle with mass in the range of ~(170-210) GeV. The light gaugino spectra studied here is generally different from other models, and in particular those with a wino dominated LSP, in that here the gluinos can be significantly lighter. The positron excess reported by the PAMELA satellite data is accounted for by annihilations of the wino LSP and their relic abundance can generally be brought near the WMAP constraints due to the late decay of a modulus field re-populating the density of relic dark matter. We also mention the recent FERMI photon constraints on annihilating dark matter in this class of models and implications for direct detection experiments including CDMS and XENON. We study these signatures in models of supersymmetry with non-minimal soft breaking terms derived from both string compactifications and related supergravity models which generally lead to non-universal gaugino masses. At the LHC, large event rates from the three-body decays of the gluino in certain parts of the parameter space are found to give rise to early discovery prospects for the gaugino sector. Excess events at the 5 sigma level can arise with luminosity as low as order 100 pb^{-1} at a center of mass energy of 10 TeV and less than ~ 1 fb^{-1} at a center of mass energy of 7 TeV., 2 columns, 9 pages, 5 figure captions

We show that the linear polarization of a gluon emerging from the reaction e + e → e + e + g + g is large - on the order of 20%. This polarization arises from the process γ + γ → quark loop → g + g, which is expected to dominate the two gluon jet cross section. The polarization can be used to test quantum chromodynamics (QCD), even if the gluon jets cannot be distinguished clearly from the background of quark jets. If the QCD prediction is accepted, our result can be used to enhance the signal of gluon jets, thereby aiding in the study of their properties.

Recent experimental evidence implies that there is no A$sub 1$ resonance. Some consequences of this for the interpretation of chiral symmetry are examined in terms of sum rules and their contribution from low-mass vector or axial-vector states. (AIP)

We suggest that the measurement of vector-meson radiation decays V ..-->.. P..gamma.. in the Primakoff-effect experiments on nuclei should be reanalyzed including isovector hadronic exchange. Its inclusion invalidates the assumption, made in data analyses, of A independence of the strength of the strong-production amplitude and could well remove the disagreement between theory and experiment for GAMMA (rho ..-->.. ..pi gamma..) and GAMMA (K*/sup 0/ ..-->.. K/sup 0/..gamma..).

We analyze the consequences of the proposal by Glashow that monojet events observed by UA1 are related to a new form of quark matter. We find that this idea requires the production of about 2 e + e − , 2 μ + μ − and 2 γ + hadron events, all at the same large effective for every monojet event explained in this way.

We point out that for $W$-pair production from ${e}^{+}{e}^{\ensuremath{-}}$ or $q\overline{q}$ beams, the correlation between the decay planes of the $W'\mathrm{s}$ is numerically negligible (at tree level) in the standard model. This occurs for the production of $\mathrm{WW}$ via intermediate fermions or gauge bosons and independently for $\mathrm{WW}$ produced via Higgs-boson exchange, and is not restricted to two-body diagrams. In general, the correlation need not vanish, and so a nonzero correlation would be a clear signal of physics beyond the standard model. Definition of the $W$-decay plane should be fairly straightforward from the decay $W\ensuremath{\rightarrow}f\overline{f}$ and, hence, the correlation measurement is experimentally feasible.

We report on a comprehensive study of supersymmetric processes which could give events similar to those observed at the CERN Sp-barpS collider. The present limited data seem to suggest a gluino mass < or approx. =20 GeV and a scalar-quark mass of 100--120 GeV, although certain other supersymmetric masses are not yet excluded. With this choice of masses we also predict that other events with different characteristics should be observed. An essential ingredient of our analysis is the inclusion of events originating from a perturbatively generated gluino distribution function inside the proton.

If low-energy supersymmetry is realized in nature, and if the appropriate supersymmetric partner of the Higgs boson, h , has a mass m h ⪡ m Z , then there is a decay chain Z → zh , followed by z → h h , which can be a significant part of all Z decays, perhaps 0.1%–1%. Depending on what is the lightest supersymmetric partner, the signature will be Z → h + missing momentum, perhaps accompanied by one or two isolated hard γ's. Decays involving both the Higgs scalar h and the pseudoscalar A are discussed, as well as ways to distinguish between them.

We examine the possibilities for searching for Higgs bosons, either directly or by studying the scattering of longitudinal W bosons, at e + e − colliders with √ s ⩾ 300 GeV. Rates for various signals are presented and compared and the luminosity needed to find Higgs physics at a given √ s is estimated. Procedures to reduce some backgrounds by appropriate cuts are discussed.

Using some new techniques we examine ways to experimentally study interactions of longitudinal {ital W} bosons in the TeV region, and to detect a heavy Higgs boson (mass {ge}1 TeV) if it exists. This is a problem that must be solved if we are eventually to fully understand and test how the SU(2){times}U(1) symmetry of the standard model is broken. To do so at a hadron collider requires methods to discriminate against large backgrounds. We use a new method based on the color properties of the signal and background, leading to a multiplicity cut, and we use analysis techniques that do not reduce the signal events by strong cuts. Our techniques do not bias {ital W} decay distributions and we conclude that it is possible to detect longitudinal {ital W} 's even in the presence of background. Results are given for how it is possible to study these matters at the Superconducting Super Collider. The use of the equivalence theorem'' between longitudinal {ital W} 's and Goldstone scalars is examined in several ways; in particular, we emphasize that in practice the equivalence does not hold numerically when the widths of heavy resonances are included in the traditional way, i.e., usingmore » the Breit-Wigner prescription. The violations are numerically large.« less

We conjecture that in the absence of new mixing effects at the weak scale the standard quark mass eigenstates and the quark weak eigenstates would coincide, and that for all three families a simple hierarchy would apply, with muo > mdo. We further assume that the observed mass inequality md > mu arises from mixing of d with a heavier quark D. This approach leads to a CKM matrix that is automatically expressed in terms of mass ratios and different from other ones that have been studied; it is consistent with experimental constraints. In addition to requiring the existence of D with a mass on the electroweak scale, in general an unambiguous prediction is that |Vtd| = |Vub|, which is soon testable. The approach can be implemented in E6-based models., Research supported in part by the US DOE and by CAICYT.

Two overriding considerations shaped the development of early research on the biological effects of microwave radiation?possible medical application (diathermy) and uncertainty about the hazards of exposure to radar. Reports in the late 1940s and early 1950s of hazards resulting from microwave exposure led to the near abandonment of medical research related to microwave diathermy at the same time that military and industrial concern over hazards grew, culminating in the massive research effort known as ?the Tri-Service program? (1957?1960). Both the early focus on medical application and the later search for hazards played important roles in dictating how this field of research developed as a science.

An analysis is made of the scientific research and values influencing the policy decisions that led to the adoption of the 1966 U.S. standard for exposure to microwave radiation. This analysis is used as a tool for understanding the problems faced by those who set standards. An effort is made to unravel the complex motivations that lay behind the adoption of the microwave standard. Based on the past record, it is suggested that standard setting remain distinct from basic scientific research and that adversary procedures be used only as a last resort in seeking consensus over a proposed standard.

Several CP-violating observables, particularly in semileptonic decays of K's, have the property that they are expected to vanish in the standard model, but are nonzero in alternative models. Thus, they provide very clean ways to test whether the standard model is the (sole) source of CP violation and to determine the properties of any other source that may enter. We mainly consider the transverse muon polarization from K/sub ..mu..//sub 3/ (which isolates S and P effective Lagrangians), and the K/sub e//sub 4/ spectrum (which contains a term that isolates V and A effective Lagrangians). We briefly comment on W/sup +- / production, and heavy-quark and -lepton decays.

If an SU(2)-singlet quark (we call it {ital D}) with mass on the weak scale exists, for which there is some motivation, it can have a large decay to a normal quark plus a Higgs boson, e.g., {ital D}{r arrow}{ital b}+{ital H}{sup 0}. If {ital M}{sub {ital D}}{approx lt}150 GeV, this converts present-day hadron colliders from being unlikely to detect Higgs bosons into useful Higgs boson factories, sensitive for {ital M}{sub {ital H}{sup 0}}{approx lt}M{sub Z}.

In order to study WW scattering or the decay of a heavy standard-model Higgs boson in the TeV region, it is necessary to use the channel W(→lν)+W(→jets). However, techniques are required for suppressing the severe background from mixed electroweak-QCD production of W+jets. We demonstrate that the charged multiplicity of the events can provide an extremely useful tool for distinguishing a jet system originating via real W decay from a jet system produced by the mixed electroweak-QCD processes. Analogous techniques will be useful for any process involving W’s→jets, whenever the W decaying to jets has pt≫mW and the primary background produces jets predominantly in a color-nonsinglet state; however the precise procedure must be optimized separately for each such process.

I. THEORETICAL CONSIDERATIONS At present there is a remarkably successful standard model of electroweak and strong interactions. There are no contradictions between experiment and theory~ Nevertheless, there are many questions which the standard model does not answer, questions of the "why" kind. The origin of quark and lepton masses is not understood, nor is the reason for generations , or how many of these there are. In the most fundamental sense, it is hoped that rare decays will occur that are not required by the standard model (that is, their rates will be nonzero if predicted to be zero in the standard model, or will differ significantly from a nonzero standard model prediction). If indeed this happens, one may expect that it will provide important clues to help answer the open questions. There are two classes of decays. Some are expected to occur at some level in the standard model (henceforth denoted as SM), and provide tests of this model. Some examples of these are given in Table i. New clues could arise from finding rates or other observables which differ from those predicted by the SM. For the second type of decays, the SM prediction is zero--they do not occur at any level. Finding them at all would demonstrate the existence of new interactions. For the various processes to be discussed below, these SM predictions will be mentioned; they are summarized in the first line of Table i. Some of the decays might give results different from the SM because of the existence of new interactions, or equivalently, the exchange of new particles. Others might be of interest as a way to discover neutrino masses because of modified kinematical distributions, or a decay into a new kind of particle. In this section we shall provide a brief description of some ideas that might lead to observable new effects. While many of the ideas suggest that new effects should occur, they do not require that they occur at any specified level. Sometimes particular models may predict an effect, but at the present level of understanding, one can usually find another model which predicts a smaller or larger effect. Rather than trying to provide complete and detailed references in the proceedings of a workshop such as this, we shall only mention a few reviews from which the literature can be traced. I Partly this is because of the perspective that the ideas discussed do provide good motivation that some effects should occur somewher~ but no partic ufar idea should be interpreted to imply that a specific prediction (beyond the SM) is more than suggestive.

Potential new ’’weak’’ interactions at very high energy and the predictions of QcD are discussed. (AIP)

Various ways that experimental evidence for supersymmetry1 might appear are considered. Possible signatures are discussed in detail. Recent events reported at the CERN collider are examined as possible evidence for supersymmetry.

It is shown that high--transverse-momentum photons originating from the process quark+gluon ..-->.. quark+photon exhibit a substantial linear polarization in perturbative quantum chromodynamics. The angular dependence of the polarization is quite sensitive to the non-Abelian structure of the interaction, and can be used to check the equality of the quark-gluon and three-gluon couplings.