Lepton-Photon 01

FOREWORD.

ACKNOWLEDGEMENTS.

Symposium Organization.

CONTENTS.

No abstract received.

A measurement of the CP violation parameter sin 2ϕ₁ based on a 29.1 fb^-1 data sample recorded at the γ(4S) resonance with the Belle detector at the KEKB asymmetric e⁺e^- collider is reported. One neutral B meson is fully reconstructed as a J/ΨK_S, Ψ(2S) K_S, χ_c1K_S, η_cK_S, J/ΨK_L or J/ΨK^*0 decay and the flavor of the accompanying B meson is identified from its decay products. From the asymmetry in the distribution of the time intervals between the two B meson decay points, we determine sin 2ϕ₁ = 0.99 ± 0.14(stat) ± 0.06(sys). Since this value is more than 6σ from zero, we can conclude that CP symmetry is violated in the neutral B meson system.

Recent developments in the theory of CP violation in the B-meson system are reviewed, with focus on the determination of sin 2β from B → J/Ψ K decays, its implications for tests of the Standard Model and searches for New Physics, and the determination of γ and α from charmless hadronic B decays.

Measurements of many Standard Model constants are clouded by uncertainties in nonperturbative QCD parameters that relate measurable quantities to the underlying parton-level processes. Generally these QCD parameters have been obtained from model calculations with large uncertainties that are difficult to quantify. The CLEO Collaboration has taken a major step towards reducing these uncertainties in determining the CKM matrix elements |V_cb| and |V_ub| using new measurements of the branching fraction and photon energy spectrum of b → sγ decays. This report includes: the new CLEO measurements of b → sγ decays, |V_cb|, and |V_ub|; the first results from CLEO III data – studies of B → Kπ, π π, and decays; mention of some other recent CLEO B decay results; and plans for operating CESR and CLEO in the charm threshold region.

B physics results from the Belle experiment are reviewed. Precise measurements of Cabbibo-Kobayashi-Maskawa matrix elements are made. Several decay modes are observed which will enable us to measure the CP angles, ϕ_i in channels other than B⁰ → ΨK⁰ modes. New rare decay modes are observed in many channels. Particular attention is paid to the first observation of the electroweak penguin-mediated decay.

Data from the first run of the BABAR detector at the PEP II accelerator are presented. Measurements of many rare B decay modes are now possible using the large data sets currently being collected by BABAR. An overview of analysis techniques and results on data collected in 2000 are described.

Preliminary KTEV results are presented based on the 1997 data set, and include an improved measurement of ℜ(∊′/∊), CPT tests, and precise measurements of τ_S and △m.

In this article the current status and latest results of the NA48 experiment at CERN are given. We present in more details the analysis performed for the Re(∊′/∊) measurement with the combined statistics accumulated during the 1998 and 1999 data periods. Reviewing the NA48 rare decay program, we select to underline the new results on the branching ratio and the a_V factor for the decay K_L → π⁰γγ and the K_L → π⁺π^- e⁺e^- CP violating decay.

Since April 1999, the KLOE experiment at DAΦNE has collected about 200 pb^-1 of data, produced in e⁺-e^- collision at the c.m. energy of 1020 MeV, the mass of the φ(1020) meson. This data has been used for detailed studies on the φ radiative decays, as well as on rare decays. The first results, based on the ~ 20 pb^-1 collected in year 2000 are presented here. Perspectives for the future data taking are also discussed.

In т physics, we are at the frontier between the completion of the LEP program and the start of analyses from b-factories, which are expected to produce results in the coming years. Nice results from CLEO are steadily delivered in the meantime. For charm, impressive progress have been achieved by fixed target experiments in the search for CP violation and oscillations. First results from b-factories demonstrate the power of these facilities in such areas. The novel measurement of the D* width by CLEO happens to be rather different from current expectations. The absence of a charm factory explains the lack or the very slow progress in the absolute scale determinations for charm decays.

I discuss two topics: i) the empirical adequacy of the Standard Model in the Flavour Sector in view of recent data; ii) the possible existence of a hidden structure in the quark masses and mixings based on textures.

Some of the recent progress in heavy quark physics is reviewed. Special attention is paid to inclusive methods for determining V_ub and factorization in nonleptonic decays. Theoretical predictions for production near threshold are also discussed.

We present an overview of rare K, D and B decays. Particular attention is devoted to those flavour-changing neutral-current processes of K and B mesons that offer the possibility of new significant tests of the Standard Model. The sensitivity of these modes to physics beyond the Standard Model and the status of their experimental study are also discussed.

This article describes the present status and physics prospects for Run II at the Fermilab Tevatron accelerator. The accelerator complex and both the collider experiments, CDF and DØ, have completed extensive upgrades resulting in a significant increase in luminosity and physics capability. The sensitivity of the Tevatron Run II physics program is expected to be about 500 times that of Run I.

While heavy ion collisions at the SPS have produced excited strongly interacting matter near the conditions for quark deconfinement, the RHIC may be the first machine capable of creating quark-antiquark plasmas sufficiently long-lived to allow deep penetration into the new phase. A comprehensive experimental program addressing this exciting physics has been put into place. Presented here are preliminary results from Au+Au at obtained during the first RHIC run and some CERN SPS results from Pb+Pb at (particularly relevant to QGP search).

I review few recent QCD results in e⁺e^-, ep and collisions. Furthermore, I discuss recent studies in power suppressed effects, ongoing progress in next-to-next-to-leading QCD calculations, and some recent puzzling results in b production.

I review two subjects in which lattice simulations are making, or can make in the future, a significant contribution to particle physics phenomenology. The first subject is the evaluation of quantities which enter into the determination of the vertex A of the unitarity triangle from experimental measurements of decay rates and mixing amplitudes. These quantities include the form-factors for semileptonic B-decays, the leptonic decay constants of the B and B_s mesons and the B-parameters for and mixing and the corresponding parameter for mixing, B_K. In the second part of this talk I will review the status and prospects for the evaluation of K → ππ amplitudes and for the subsequent study of the △I = 1/2 rule and the evaluation of ε′/ε.

An overview of the field of Chiral Lagrangians is given. This includes Chiral Perturbation Theory and resummations to extend it to higher energies, applications to the muon anomalous magnetic moment, ∊′/∊ and others.

The increasing precision of the measurements on the proton structure and an improved treatment of the correlated systematic experimental errors constitute a major step forward in our understanding of the flavour decomposition of the proton and the momentum distributions of the various flavours. Together with theoretical progress on the next-to-next-to-leading order QCD corrections to deep inelastic scattering processes, the proton measurements already imply a new level of precision for the strong coupling constant α_s. The progress in the measurements on the quantum fluctuations of the photon allows questions on the universal properties of hadronic structures to be addressed.

Recent theoretical developments to calculate cross sections of hadronic objects in the high energy limit are summarised and experimental attempts to establish the need for new QCD effects connected with a resummation of small hadron momentum fractions x are reviewed. The relation between small-x parton dynamics and the phenomenon of diffraction is briefly out-lined. In addition, a search for a novel, non-perturbative QCD effect, the production of QCD instanton induced events, is presented.

The most recent theoretical and experimental results in the field of diffractive scattering are reviewed. A parallel between the two current theoretical approaches to diffraction, the DIS picture in the Breit frame and the dipole picture in the target frame, is given, accompanied by a description of the models to which the data are compared. A recent calculation of the rescattering corrections, which hints at the universality of the diffractive parton distribution functions, is presented. The concept of generalized parton distributions is discussed together with the first measurement of the processes which might give access to them. Particular emphasis is given to the HERA data, to motivate why hard diffraction in deep inelastic scattering is viewed as an unrivalled instrument to shed light on the still obscure aspects of hadronic interactions.

Recent progress in the field of spin physics of high energy particle interactions is reviewed with particular emphasis on the spin structure functions as measured in polarized deep inelastic lepton-nucleon scattering (DIS). New measurements are presented to obtain more direct information on the composition of the nucleon angular momentum, with results from semi-inclusive DIS accessing flavour-separated parton distribution functions (PDF) and with first data from hard exclusive reactions which may be interpreted in terms of recently developed generalizations of parton distribution functions (GPD). Finally, experimental prospects are outlined which will lead to a further development of the virtues of QCD phenomenology of the spin structure of the nucleon.

Rapporteur talk at the Lepton-Photon Conference, Rome, July 2001: reviewing the evidence and strategies for understanding scalar mesons, glueballs and hybrids, the gluonic Pomeron and the interplay of heavy flavours and light hadron dynamics. Dedicated to the memory of Nathan Isgur, long-time collaborator and friend, whose original ideas in hadron spectroscopy formed the basis for much of the talk.

After a comment on the performance of LEP some highlights of the LEP1 and LEP2 physics programmes are reviewed. The talk concentrates on the precision measurements at the Z resonance, two fermion production above the Z, W⁺W^- production, ZZ production, indirect limits on the Higgs mass, LEP contributions to the exploration of the CKM matrix, and on the LEP measurements of α_s.

Motivations for physics beyond the Standard Model are reviewed, with particular emphasis on supersymmetry at the TeV scale. Constraints on the minimal supersyymetric extension of the Standard Model with universal soft supersymmetry-breaking terms (CMSSM) are discussed. These are also combined with the supersymmetric interpretation of the anomalous magnetic moment of the muon. The prospects for observing supersymmetry at accelerators are reviewed using benchmark scenarios to focus the discussion. Prospects for other experiments including the detection of cold dark matter, μ → eγ and related processes, as well as proton decay are also discussed.

The present experimental and theoretical knowledge of the physics of electroweak symmetry breaking is reviewed. Data still favor a light Higgs boson, of a kind that can be comfortably accommodated in the Standard Model or in its Minimal Supersymmetric extension, but exhibit a non–trivial structure that leaves some open questions. The available experimental information may still be reconciled with the absence of a light Higgs boson, but the price to pay looks excessive. Recent theoretical ideas, linking the weak scale with the size of possible extra spatial dimensions, are briefly mentioned. It is stressed once more that experiments at high–energy colliders, such as the Tevatron and the LHC, are the crucial tool for eventually solving the Higgs puzzle.

A summary is given of the present status of the theory and experiment of the anomalous magnetic moment of the muon. A difference between predicted and measured values is an indication of physics beyond the Standard Model. A new experimental measurement has produced a value which differs from a recent Standard Model prediction by about 1.6 standard deviations. When first announced, the discrepancy was about 2.6 standard deviations, but theorists have recently found an error in the sign of the largest term in the standard model hadronic light-by-light contribution which reduces the difference. Additional data are being analyzed and elements of the theory are being scrutinized to provide, in the future, a sharper test of theory.

The status of searches for new particles and new physics during the past year at the Fermilab Tevatron, at HERA and at LEP is summarized. A discussion of the hints for the Standard Model Higgs boson from LEP2 data is presented. Searches for non-Standard Model Higgs bosons are also described. Many searches have been carried out for the particles predicted by supersymmetry theories, and a sampling of these is given. There have also been searches for flavor changing neutral currents in the interactions of the top quark. In addition, searches for excited leptons, leptoquarks and technicolor are summarized.

Super-Kamiokande is a 50 Kiloton water-Cherenkov that detects neutrinos in the MeV energy range that are produced in the Sun and neutrinos in the GeV energy range produced in the atmosphere by cosmic rays. The detector has been operational since April of 1996. In this paper results of our most recent analysis will be presented on both atmospheric and solar neutrinos.

K2K is a long baseline neutrino oscillation experiment using a neutrino beam produced at the KEK 12 GeV PS, a near detector complex at KEK and a far detector (Super-Kamiokande) in Kamioka, Japan. The experiment was constructed and is being operated by an international consortium of institutions from Japan, Korea, and the US. The experiment started taking data in 1999 and has successfully taken data for about two years. K2K is the first long baseline neutrino oscillation experiment with a baseline of order hundreds of km and is the first accelerator based neutrino oscillation experiment that is sensitive to the Super-Kamiokande allowed region obtained from the atmospheric neutrino oscillation analysis. A total of 44 events have been observed in the far detector during the period of June 1999 to April 2001 corresponding to 3.85 × 10¹⁹ protons on target. The observation is consistent with the neutrino oscillation expectations based on the oscillation parameters derived from the atmospheric neutrinos, and the probability that this is a statistical fluctuation of non-oscillation expectation of is less than 3%.

We describe here the measurement of the flux of neutrinos created by the decay of solar ⁸B by the Sudbury Neutrino Observatory (SNO). The neutrinos were detected via the charged current (CC) reaction on deuterium and by the elastic scattering (ES) of electrons. The CC reaction is sensitive exclusively to ν_e's, while the ES reaction also has a small sensitivity to ν_μ's and ν_τ's. The flux of ν_e's from ⁸B decay measured by the CC reaction rate is . Assuming no flavor transformation, the flux inferred from the ES reaction rate is . Comparison of φ^CC (ν_e) to the Super-Kamiokande Collaboration's precision value of φ^ES(ν_x) yields a 3.3σ difference, assuming the systematic uncertainties are normally distributed, providing evidence that there is a non-electron flavor active neutrino component in the solar flux. The total flux of active ⁸B neutrinos is thus determined to be 5.44±0.99 × 10⁶ cm^-2s^-1, in close agreement with the predictions of solar models.

No abstract received.

Neutrino physics is going through a revolutionary progress. In this talk I review what we have learned and why neutrino mass is so important. Neutrino masses and mixings are already shedding new insight into the origin of flavor. Given the evidences for neutrino mass, leptogenesis is gaining momentum as the origin of cosmic baryon asymmetry. Best of all, we will learn a lot more in the coming years.

Dark matter is at present one of the most exciting field of particle physics and cosmology. We review the status of undergound experiments looking for cold and hot dark matter.

Although cosmic rays were discovered 90 years ago, we do not know how and where they are accelerated. There is compelling evidence that the highest energy cosmic rays are extra-galactic — they cannot be contained by our galaxy's magnetic field anyway because their gyroradius exceeds its dimensions. Elementary elementary-particle physics dictates a universal upper limit on their energy of 5 × 10¹⁹ eV, the so-called Greisen-Kuzmin-Zatsepin cutoff; however, particles in excess of this energy have been observed, adding one more puzzle to the cosmic ray mystery. Mystery is nonetheless fertile ground for progress: we will review the facts and mention some very speculative interpretations. There is indeed a realistic hope that the oldest problem in astronomy will be resolved soon by ambitious experimentation: air shower arrays of 10⁴ km² area, arrays of air Cerenkov detectors and kilometer-scale neutrino observatories.

Over the past three years we have determined the basic features of our Universe. It is spatially flat; accelerating; comprised of 1/3 a new form of matter, 2/3 a new form of energy, with some ordinary matter and a dash of massive neutrinos; and it apparently began from a great burst of expansion (inflation) during which quantum noise was stretched to astrophysical size seeding cosmic structure. This "New Cosmology" greatly extends the highly successful hot big-bang model. Now we have to make sense of it. What is the dark matter particle? What is the nature of the dark energy? Why this mixture? How did the matter – antimatter asymmetry arise? What is the underlying cause of inflation (if it indeed occurred)?

No abstract received.

An electron-positron linear collider in the energy range between 500 and 1000 GeV is of crucial importance to precisely test the Standard Model and to explore the physics beyond it. The physics program is complementary to that of the Large Hadron Collider. Some of the main physics goals and the expected accuracies of the anticipated measurements at such a linear collider are discussed. A short review of the different collider designs presently under study is given including possible upgrade paths to the multi-TeV region. Finally a framework is presented within which the realisation of such a project could be achieved as a global international project.

European, Japanese, and US Neutrino Factory designs are presented. The main R&D issues and associated R&D programs, future prospects, and the additional issues that must be addressed to produce a viable Muon Collider design, are discussed.

No abstract received.

Important new results have been presented at this conference. The direct violation of CP in K⁰ → π+π has been firmly established in two independent experiments, NA48 at CERN and KTeV at Fermilab. Both Babar at SLAC and Belle at KeK have determined the CP violation in oscillations through the study of the golden K_S + Ψ decay mode. The observed CP violation agrees with the expectations of the Standard model, based on the quark-mixing phenomenon. The first results of the Sudbury Neutrino Observatory, SNO, suggest that the long-lasting solar neutrino puzzle has been finally solved in terms of neutrino oscillations. Results appeared after the conference which modify the theoretical prediction of the muon anomaly. This new result, if confirmed, would drastically reduce the significance of the discrepancy between the theoretically expected value for the muon anomaly and the recent ressults of the Brookhaven experiment.

Poster Session.

Contributed Papers.

LP01 Participants.

Author Index.