Transversity

Transversity 2008, the second workshop on OC Transverse polarization phenomena in hard processesOCO follows the first one held in Como after three years. As in that case, the event comes at the end of a two-years project financed by the Italian Ministry of Education. In the time between the two Workshops, decisive steps towards the revealing of the transverse spin structure of the proton were taken on both the theoretical and experimental sides. The milestone of the first extraction of Transversity and the Sivers function for the u- and d-quarks deserves a special mention. In the same period, historic experiments that in the last decade contributed to the first pioneering measurements in the SIDIS sector, have concluded their data taking, and their place is being taken by upgrades of existing or new facilities. These are the result of the new interesting phenomena which are appearing and call for additional experimental information and novel experimental techniques. Over 80 physicists took part in the Workshop. Equally involved were experimentalists and theoreticians engaged in investigating the nature of transverse spin. The heterogeneous public favoured vivid discussions and fruitful exchange of up-to-date theoretical and experimental ideas on this constantly evolving subject."

The notion of transversity in hadronic physics has been with us for over 25 years. Intriguing though it might have been, for much of that time transversity remained an intangible and remote object, of interest principally to a few theoreticians. In recent years transversity and transverse-spin effects in general have grown as both theoretical and experimental areas of active research. This increasing attention has now matured into a thriving field with a driving force of its own. The ever-growing bulk of data on asymmetries in collisions involving transversely polarised hadrons demands a more solid and coherent theoretical basis for its description. Indeed, it now appears rather clear that transversity and other closely related properties play a significant role in such phenomena.As part of a Ministry-funded inter-university Research Project, this workshop was organised to gather together experimentalists and theoreticians engaged in investigating the nature of transverse spin in hadronic physics, with the intent of favouring the exchange of up-to-date theoretical and experimental ideas and news on the subject. Over 70 physicists took part and very nearly all the major experiments involved in transverse-spin studies were officially represented, as too were the main theory groups working in the field. New results and new analyses sparked many interesting and lively discussions.

This book is devoted to the theory and phenomenology of transverse-spin effects in high-energy hadronic physics. Contrary to common past belief, it is now rather clear that such effects are far from irrelevant. A decade or so of intense theoretical work has shed much light on the subject and brought to surface an entire class of new phenomena, which now await thorough experimental investigation. Over the next few years a number of experiments world-wide (at BNL, CERN, DESY and JLAB) will run with transversely polarised beams and targets, providing data that will enrich our knowledge of the transverse-spin structure of hadrons. It is therefore timely to assess the state of the art, and this is the principal aim of the volume.An outline of the book is as follows. After a few introductory remarks (Chapter 1), attention is directed in Chapter 2 to transversely polarised deeply-inelastic scattering (DIS), which probes the transverse spin structure function 2. This existing data are reviewed and discussed (for completeness, a brief presentation of longitudinally polarised DIS is also provided). In Chapter 3 the transverse-spin structure of the proton is illustrated in detail, with emphasis on the transversity distribution and the twist-three parton distribution contributing to g2. Model calculations of these quantities are also presented. In Chapter 4, the QCD evolution of transversity is studied at leading and next-to-leading order. Chapter 5 illustrates the g2 structure function and its related sum rules within the framework of perturbative QCD. The last three chapters are devoted to the phenomenology of transversity, in the context of Drell-Yan processes (Chapter 6), inclusive leptoproduction (Chapter 7) and inclusive hadroproduction (Chapter 8). The interpretation of some recent single-spin asymmetry data is discussed and the prospects for future measurements are reviewed.

One of the main challenges in nuclear and particle physics in the last 20 years has been to understand how the proton''s spin is built up from its quark and gluon constituents. Quark models generally predict that about 60% of the proton''s spin should be carried by the spin of the quarks inside, whereas high energy scattering experiments have shown that the quark spin contribution is small OCo only about 30%. This result has been the underlying motivation for about 1000 theoretical papers and a global program of dedicated spin experiments at BNL, CERN, DESY and Jefferson Laboratory to map the individual quark and gluon angular momentum contributions to the proton''s spin, which are now yielding exciting results. This book gives an overview of the present status of the field: what is new in the data and what can be expected in the next few years. The emphasis is on the main physical ideas and the interpretation of spin data. The interface between QCD spin physics and the famous axial U(1) problem of QCD (eta and etaprime meson physics) is also highlighted. Sample Chapter(s). Chapter 1: Introduction (159 KB). Contents: Spin Experiments and Data; Dispersion Relations and Spin Sum Rules; g 1 Spin Sum Rules; Fixed Poles; The Axial Anomaly, Gluon topology and g (0) A; Chiral Symmetry and Axial U(1) Dynamics; QCD Inspired Models of the Proton Spin Problem; The Spin-Flavour Structure of the Proton; QCD Fits to g 1 Data; Polarized Quark Distributions; Polarized Glue o g(x, Q 2 ); Transversity; Deeply Virtual Compton Scattering and Exclusive Processes; Polarized Photon Structure Functions; Conclusions and Open Questions: How Does the Proton Spin?. Readership: Academics, as well as physicists working on particle and nuclear physics at the interface of theory and experiment.

The Lepton-Photon symposiums ? as represented by the contributions in this volume ? are among the most popular conferences in high energy physics since they give an in-depth snapshots of the status of the field as provided by leading experts.The volume covers the latest results on flavor factories, quantum chromodynamics (QCD), electroweak physics, dark matter searches, neutrino physics and cosmology, from a phenomenological point of view. It also offers a glimpse of the immediate future of the field through summaries on the status of the next generation of high energy accelerators and planned facilities for astroparticle physics.The review nature of the articles makes the volume particularly useful to students, as well as being of interest to established researches in high-energy physics and related fields.

This 2nd edition is an extensive update of 'B Decays”. The revisions are necessary because of the extensive amount of new data and new theoretical ideas. This book reviews what is known about b-quark decays and also looks at what can be learned in the future.The importance of this research area is increasing, as evidenced by the approval of the luminosity upgrade for CESR and the asymmetric B factories at SLAC and KEK, and the possibility of experiments at hadron colliders.The key experimental observations made thus far, measurement of the lifetimes of the different B species, B0-B0 mixing, the discovery of “Penguin” mediated decays, and the extraction of the CKM matrix elements Vub and Vcb from semileptonic decays, as well as more mundane results, are described in great detail by the experimentalists who have been closely involved with making the measurements. Theoretical progress in understanding b-quark decays using HQET and lattice gauge techniques are described by theorists who have developed and used these techniques.Synthesizing the experimental and theoretical information, several articles discuss the implications for the “Standard Model” and how further tests can be done using measurements of CP violation in the B system.

The Proceedings include talks given at the 4th Workshop on Exclusive Reactions at High Momentum Transfer at Jefferson Lab, Newport News, VA, USA, the world''s leading facility performing research on nuclear, hadronic and quark-gluon structure of matter. Exclusive reactions are becoming one of the major sources of information about the deep structure of the nucleons and other hadrons. The workshop focused on the application of a variety of exclusive reactions at high momentum transfer, utilizing unpolarized and polarized beams and targets, to obtain information about nucleon ground state and excited state structure at short distances. This is a subject which is central to the programs of current accelerators and especially planned future facilities. The topics include: generalized parton distributions, deeply virtual Compton scattering, deeply virtual meson production (DVMP), transverse structure of hadrons (TMD), hadron form factors - elastic and transition, quantum chromodynamics (perturbative, non-perturbative, lattice calculations), and physics to study at an Electron Ion Collider.

The first precision measurements on CP violation in the B system are reported. Both the BELLE and the BABAR collaboration presented, among others, results for sin 2ß with much improved accuracy. Results from the Sudbury Neutrino Observatory, SNO, also deserve to be mentioned. The convincing evidence of solar neutrino oscillations had been presented by SNO prior to the conference; a full presentation was given at the conference. An incredibly precise measurement of the anomalous magnetic moment of the muon is reported, a fresh result from the Brookhaven National Laboratory. Apart from these distinct physics highlights, there are also the first results from the new Tevatron run and from the relativistic heavy ion collider RHIC. Theorists write of our ever better understanding of the Standard Model and of what might lie beyond. Risky as it is to highlight only a couple of exciting subjects, it is merely meantto whet the appetite for further reading.