I review the many ways of obtaining information about the CKM matrix through CP violation in the $B$ system. I include direct and indirect CP violation, the role of penguins and isospin analysis, tagging, and $B\to DK$ decays. I also discuss recent developments showing how to use $SU(3)$ flavor symmetry, along with some dynamical approximations, to extract from $B$ decays to $\pi\pi$, $\pi K$ and $K\kbar$ the weak CKM phases, the strong phase shifts, and the sizes of the various contributing diagrams. Finally, I briefly show what can be learned from an exact treatment of the CKM matrix. (Talk given at the 5th Conference on the Intersections of Particle and Nuclear Physics, St. Petersburg, Florida, USA, May 31-June 6, 1994.)
In this talk I will show that the two-Higgs doublet model with vacuum CP violation and approximate global U(1) family symmetries may provide one of the simplest and most attractive models for understanding the origin and mechanisms of CP violation. It is shown that the mechanism of spontaneous symmetry breaking provides not only a mechanism for generating masses of the bosons and fermions, but also a mechanism for creating CP-phases of the bosons and fermions, so that CP violation occurs, after spontaneous symmetry breaking, in all possible ways from a single CP phase of the vacuum and is generally classified into four types of CP-violating mechanism. A new type of CP-violating mechanism in the charged Higgs boson interactions of the fermions is emphasized and can provide a consistent description for both established and reported CP-, P- and T-violating phenomena. Of particular importance is the new source of CP violation for charged Higgs boson interactions that lead to the value of ϵ'/ϵ as large as 10^-3 independend of the CKM phase. (Invited Talk at the 5th Conference on the Intersections of Particle and Nuclear Physics, May 31-June 6, 1994, at St. Petersburg, Florida, to appear in the Proceedings)
Because of the long range of the gauge interactions, the collective behaviour of quarks and gluons plays a decisive role in the transport processes. Collective effects, like Debye screening and Landau damping, remove the unphysical infrared divergences of the transport cross-sections and provide finite relaxation rates. I review here a theory of the plasma collective excitations that has been recently developed. It is based on kinetic equations derived from the general QCD Dyson-Schwinger equations, in the weak coupling limit. I present new, truly non-abelian, collective excitations, which correspond to nonlinear color oscillations of the QCD plasma.
Characteristics of LAMBDA, SIGMA, and XI hypernuclei are investigated within the relativistic mean-field theory. The spin-orbit splitting is very sensitive to the value of tensor coupling f(omegaY). A self-consistent treatment together with elimination of the hyperon self-coupling contribution is crucial for determining the V(rho) contribution to the hyperon binding.
The nonmesonic weak decay of Λ hypernuclei is studied in a relativistic shell model framework which includes a full strangeness‐changing weak ΛN→NN One‐Boson‐Exchange transition potential as well as a realistic ΛN short‐range correlation function. The total decay rate and the proton asymmetry, which represents a measure of the parity‐violating to parity‐conserving amplitudes, are in agreement with present experimental errors while the neutron‐to‐proton‐induced ratio differs by more than a factor of two. In general, the observables were found to be dominated by the pion‐exchange mechanism since the contributions of heavier mesons are suppressed by form factors and short‐range correlations.
We report results from Fermilab experiment E706 on nuclear target effects in the production of π0 and η mesons, direct photons, and massive jet and pion pairs at large transverse momenta. The data are presented for 515 GeV/c π− beam incident on Be and Cu targets over the kinematic regions of 4
Astrophysical implications of neutrino mass and mixings are discussed. The status of solar and atmospheric neutrino problems, and recent developments concerning nuclear physics input to solar models and solar opacities are reviewed. Implications of neutrino mass and mixings in supernova dynamics are explored. The effects of supernova density fluctuations in neutrino propagation is described.
Astrophysics is gaining increased attention from the particle and nuclear physics communities, as budget cuts, delays, and cancellations limit opportunities for breakthrough research at accelerator laboratories. Observations of cosmic rays (protons and nuclei), gamma rays and neutrinos present a variety of puzzles whose eventual solution will shed light on many issues ranging from the nature of fundamental interactions at extreme energies to the mechanisms of astrophysical sources. Several important detectors are just beginning full-scale operation and others are beginning construction.
The phenomenological sum-rule-based approach is used to discuss the quark composition dependence of some static electroweak characteristics of nucleons. The role of the nonvalence degrees of freedom (the nucleon sea partons and/or peripheral meson currents) is shown to be important to select and make use of the relevant symmetry parametrization of hadron observables. The implication of hidden strangeness of the nucleon for the recently observed OZI-rule violation in antinucleon-nucleon annihilation reactions is pointed out. Some further consequences of a general sum rule approach to baryon electroweak coupling constants are presented and discussed.
Nucleon elastic form factors parametrize the internal structure of the nucleon as probed by the electroweak force. In particular, they provide information on the distribution of nucleon charge among sea and valence quarks and on the distribution of flavor in the nucleon. The recent measurements are reviewed and new techniques to experimentally determine the form factors are described. Future plans at the new high duty‐factor electron machines are discussed.
Observations of high-energy gamma rays from astronomical sources have revolutionised our view of the cosmos. Gamma rays with energies up to similar to 10 GeV can be observed directly with space-based instruments. Above 100 GeV the low flux of gamma lays requires one to utilise ground-based instruments. Milagro is a new type of gamma-ray detector based on water Cerenkov technology. This new design will enable Milagro to continuously observe the entire overhead sky, and be sensitive to cosmic rays with energies above similar to 250 GeV. These attributes make Milagro an ideal detector for the study of high-energy transient phenomenon.
We report a study of quark flow in 20 exclusive reactions measured at Brookhaven National Laboratory’s AGS with a beam momentum of 5.9 GeV/c at 90° in the center of mass. This experiment confirms the strong quark flow reaction mechanism dependence of two‐body hadron scattering at large angles seen at 9.9 GeV/c. Large differences in cross sections for different reactions are consistent with the dominance of quark interchange in these 90° reactions, and indicate that pure gluon exchange and quark/antiquark annihilation diagrams are less important.
We present preliminary results from Fermilab E791 on D0−D0 mixing and doubly Cabibbo‐suppressed decays (DCSD) of the D0 and D+ mesons. The time dependence of the wrong‐sign signal (D0[K+π−) is used to establish separate limits on DCSD and mixing. From one third of our data we obtained rmix<0.47%, rDCSD<2.7% at the 90% confidence level.
I review the most interesting features of the dimuon mass spectra, as measured by the NA38 and HELIOS‐3 experiments, in p‐A and S‐A collisions: the φ/(ρ+ω) enhancement, the J/ψ and ψ′ suppression and the ‘‘excess’’ continuum production in sulphur interactions relative to the linear extrapolation of the p‐A results.
Among the 14 contributions selected for oral presentation, 3 were devoted to the structure of electro‐weak interactions, 1 to charge symmetry breaking, 4 to time reversal non‐invariance, and 6 to parity‐non‐conservation. Most of the contributions were dealing with experiment (11/14) and the first and last topics were partly covered in plenary sessions, respectively by G. L. Greene and J. D. Bowman. If PCT invariance is assumed, the topics on time‐reversal non‐invariance should not be independent on PC violation discussed in another parallel session. The difference resides in the fact that the study of time‐reversal non‐invariance does not require to consider the charge‐conjugate process. All the contributions refer to an energy below the range of 1 to 150 GeV and beyond assigned to the conference. Many of them nevertheless address questions relevant to this range.
This paper summarizes a decay amplitude analysis of photoproduced D mesons using data collected by the fixed‐target photoproduction experiment E687 at Fermilab. The results of a Dalitz plot analysis are compared to predictions from models of nonleptonic charm decay.
The 5th Conference on the Intersections of Particle and Nuclear Physics included five sessions on hypernuclear physics and exotic hadron spectroscopy. This paper provides a brief summary of the highlights of these sessions.
We calculate the asymmetry in the missing-momentum distribution from the (e,e'p) reaction in a relativistic formalism. Longitudinal and transverse response functions are evaluated in parallel kinematics as a function of the three-momentum transfer to the nucleus. Analytic expressions for the responses are obtained in a relativistic plane-wave impulse approximation. These expressions reveal a large asymmetry in the momentum distribution, at the plane-wave level, induced by the lower components of the bound-state wave functions. These relativistic effects contaminate any attempt to infer color transparency from a measurement of the asymmetry in the (e,e'p) reaction.
Measurements have been performed on the helicity dependence of the neutron resonance cross section for many nuclei by our TRIPLE Collaboration. A large number of parity violations are observed. Generic enhancements amplify the signal for symmetry breaking and the stochastic properties of the compound nucleus permit the strength of the symmetry-breaking interaction to be determined without knowledge of the wave functions of individual states. A total of 15 nuclei have been analyzed with this statistical approach. The results are summarized.
A review is made of those past, present, and planned experiments at the AGS whose primary purpose is to determine whether the H‐dibaryon exists. Preliminary results are given for experiment E813, based on partially‐completed analysis.
