Transversity 2008: Proceedings of the Second Workshop on Transverse Polarization Phenomena in Hard Processes, Ferrar, Italy 28-31 Mary 2008

Annotation. Transversity 2008, the second workshop on "Transverse polarization phenomena in hard processes" 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 CONTENTS......Page 12 Preface......Page 6 Organizing Committees......Page 8 Acknowledgment......Page 10 Introduction......Page 16 Purpose and status of the italian transversity project F. Bradamante......Page 18 Contributions......Page 20 1. Transversity from 1978 to 2008......Page 22 2.1. Double transverse spin asymmetries......Page 28 2.2. TMD single spin asymmetries......Page 30 2.3. Non-TMD single spin asymmetries......Page 33 3. Routes to transversity......Page 35 3.1. Transversity GPD......Page 36 References......Page 37 2. Why the problem is non-trivial......Page 40 2.1. The traditional approach......Page 41 2.2. A new approach......Page 42 4. Sum rules......Page 43 5. A new classification of sum rules......Page 44 6. Conclusions......Page 45 References......Page 46 1. The Collins and Sivers mechanisms......Page 47 2. The HERMES experiment......Page 48 3. Extraction of Collins and Sivers moments......Page 49 4. A method for the estimation of the acceptance effects......Page 52 References......Page 54 1. Introduction......Page 55 2.1. Collins asymmetry......Page 56 2.3. Other single spin asymmetries......Page 60 3. Two hadron asymmetries......Page 61 References......Page 63 1. Single Spin asymmetries......Page 64 2. Data sample and analysis......Page 66 2.1. Results......Page 67 References......Page 71 New preliminary results on the of transversity distribution and the Collins fragmentation functions M. Anselmino, M. Boglione, U. D’Alesio, A. Kotzinian, F. Murgia, A. Prokudin, S. Melis and C. Türk......Page 72 References......Page 78 Sivers effect in SIDIS pion and kaon production M. Anselmino, M. Boglione, U. D’Alesio, A. Kotzinian, S. Melis, F. Murgia, A. Prokudin and C. Türk......Page 79 References......Page 86 1. Impact Parameter Dependent PDFs and SSAs......Page 87 2. The Force on a Quark in SIDIS......Page 90 Acknowledgments......Page 93 References......Page 94 1. Introduction and Definitions......Page 95 2. Relations between GPDs and TMDs......Page 97 3. Generalized Transverse Momentum Dependent Parton Distributions......Page 99 4. Conclusion......Page 101 References......Page 102 1. Transversity questions......Page 103 2. Hadronic and partonic models......Page 104 3. Regge cut model......Page 106 4. Transversity, chiral odd GPDs and helicity......Page 107 5. Exclusive π0 electroproduction observables and results......Page 108 References......Page 110 1. General framework......Page 111 2. Parameter values and results......Page 115 References......Page 118 1. Introduction......Page 119 3. Exclusive ρ0 production......Page 120 4. Results for exclusive ρ0 production......Page 122 5. Future GPD measurements at COMPASS......Page 123 7. Experimental realization......Page 124 References......Page 126 1. Introduction......Page 127 3.1. PHENIX......Page 128 3.2. BRAHMS......Page 129 4. Results......Page 130 5. Conclusions......Page 135 References......Page 136 1. Introduction......Page 137 2. The generalized parton model......Page 138 3. Collins effect in pp collisions: a reassessment......Page 139 4. Sivers and Collins effects in p p h + X: a preliminary update......Page 142 References......Page 144 1. The Sivers function in Constituent Quark Models......Page 145 2. The Sivers function from neutron (3He) targets......Page 149 References......Page 151 1. Introduction and Formalism......Page 153 2. Invariant Cross Sections......Page 155 4. The Sivers Effect......Page 157 References......Page 160 1. Introduction......Page 161 2.1. Overview......Page 162 2.2. Angular distributions of Drell-Yan and the Boer-Mulders function......Page 163 2.3. Results from Fermilab E866......Page 165 3. Future prospects at Frmilab and J-PARC......Page 168 References......Page 170 1. Introduction......Page 172 3. PAX accelerator set-up......Page 173 4. Expected precision of the experiment......Page 174 References......Page 176 1. Introduction......Page 178 2. The PDFs......Page 179 4. COMPASS apparatus and upgrade......Page 182 References......Page 183 1. Introduction and Theoretical Motivation......Page 184 2. The COMPASS Experiment......Page 186 4. Results......Page 187 References......Page 191 1. Introduction......Page 192 3. Multidimensional analysis......Page 194 3.1. The unfolding extraction procedure......Page 196 References......Page 199 1. Introduction......Page 200 2. Transversity in Pion-Pair Production......Page 201 4. Extraction of the Asymmetries......Page 203 References......Page 207 1. Introduction......Page 208 2. Ways from Sivers function to twist three......Page 209 3. From the Sivers function to gluonic poles......Page 210 4. Colour factors and the transition from large to small transverse momenta......Page 213 5. Discussion and conclusions......Page 215 References......Page 216 1. Introduction......Page 218 2.1. Type-I observables......Page 219 3. Matches and mismatches: semi-inclusive DIS case......Page 220 3.1. Type-I structure functions......Page 222 3.2. Type-II structure functions......Page 224 References......Page 225 1. Introduction......Page 226 2. Properties of h......Page 227 3. Pretzelosity in the bag model......Page 228 5. Preliminary COMPASS data & prospects at JLab......Page 230 6. Conclusions......Page 231 References......Page 232 1. Introduction......Page 234 2. TMD Correlators in the Spectator Framework......Page 235 3. Azimuthal Asymmetries......Page 240 References......Page 243 1. A Completeness Paradox of Confinement......Page 244 2.1. Gauss’ Law......Page 245 2.2. Embedded Frames and Connections......Page 246 3. Two Kinds of Completeness......Page 247 4. Reduction......Page 248 5. The Soffer Bound......Page 249 References......Page 251 1. Introduction......Page 252 2. Helicity distribution function......Page 254 3. Azimuthal asymmetries on transversely polarized target......Page 255 5. Conclusions......Page 258 References......Page 259 1. Introduction......Page 260 2. Formalism......Page 261 3. Numerical results......Page 263 References......Page 267 1. Introduction......Page 268 2. Gluonic pole matrix elements......Page 272 3. The spectator model approach......Page 273 References......Page 274 1. Introduction......Page 275 2. SIDIS with unpolarized target......Page 276 3. SIDIS with longitudinally polarized target......Page 278 4. Future measurements with CLAS at 6 GeV......Page 279 4.1. TMD Measurements with JLab at 12 GeV......Page 281 References......Page 283 1. Introduction......Page 285 2.1. Definitions and properties......Page 286 2.2. LCWFs representation......Page 287 2.3. Numerical results......Page 289 3. Nucleon to pion TDAs......Page 290 References......Page 292 1. Introduction......Page 294 2. Strategies Towards Polarized Antiprotons......Page 295 3. Spin-Transfer Measurement by Depolarization......Page 296 References......Page 298 Closing Lecture......Page 300 2. The first glance at the transversity in the proton......Page 302 3. Polarized antiprotons for PAX......Page 308 4. Known knowns, known unknowns, unknown knowns and unknown unknowns......Page 309 5. Apologies and Acknowledgments......Page 310 References......Page 311 Author Index......Page 312