Download or read book Single Spin Asymmetries in Semi inclusive Deep Inelastic Scattering and Drell Yan Processes written by and published by . This book was released on 2013 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: We examine in detail the diagrammatic mechanisms which provide the change of sign between the single transverse spin asymmetries measured in semi-inclusive deep inelastic scattering (SIDIS) and in the Drell-Yan process (DY). This asymmetry is known to arise due to the transverse spin dependence of the target proton combined with a T-odd complex phase. Using the discrete symmetry properties of transverse spinors, we show that the required complex phase originates in the denominators of rescattering diagrams and their respective cuts. For simplicity, we work in a model where the proton consists of a valence quark and a scalar diquark. We then show that the phases generated in SIDIS and in DY originate from distinctly different cuts in the amplitudes, which at first appears to obscure the relationship between the single-spin asymmetries in the two processes. Nevertheless, further analysis demonstrates that the contributions of these cuts are identical in the leading-twist Bjorken kinematics considered, resulting in the standard sign-flip relation between the Sivers functions in SIDIS and DY. Physically, this fundamental, but yet untested, prediction occurs because the Sivers effect in the Drell-Yan reaction is modified by the initial-state "lensing" interactions of the annihilating antiquark, in contrast to the final-state lensing which produces the Sivers effect in deep inelastic scattering.
Download or read book PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP ENTITLED SINGLE SPIN ASYMMETRIES VOLUME 75 written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Single-transverse spin asymmetries (SSA) in strong interactions have a long history, starting from the 1970s and 1980s when surprisingly large single-transverse spin asymmetries were observed in p+p [yields] [pi]X and pp [yields] [Lambda] + X, where really none were expected. They have again attracted much interest in recent years from both experimental and theoretical sides. In particular, first measurements by the STAR, PHENIX, and BRAHMS collaborations at RHIC have now become available which again reveal large single transverse spin asymmetries for hadron production in polarized proton proton scattering. This extends the SSA observations from the fixed target energy range to the collider regime. Meanwhile, experimental studies in Deep Inelastic Scattering by the HERMES collaboration at DESY, SMC at CERN, and CLAS at JLab also show a remarkably large SSA in semi-inclusive hadron production, [gamma]*p [yields] [pi]X, when the proton is transversely polarized. On the theoretical side, there are several approaches to understanding SSA within Quantum Chromodynamics (QCD). For example, to explain the large SSAs for hadron production in hadron collisions, a mechanism that takes into account the contribution from quark-gluon-quark correlations (twist-3) in the nucleon was proposed. On the other hand, possible origins of SSA in DIS and hadronic scattering were also found in leading-twist transverse momentum dependent parton distributions. Current theoretical efforts aim at a better conceptual understanding of these two types of mechanisms, and of their connections. We were very happy at this timely date to bring together the theorists and experimentalists of this field to review and discuss the current theoretical status and the latest experimental results. The whole workshop contained 25 formal talks, both experiment (15) and theory (10), and a few informal talks and many fruitful discussions. The topics covered all the relevant SSA observables, including in Deep Inelastic Scattering, the Drell-Yan process, and in inclusive hadron production and dijet correlations at hadron colliders. There were not only discussions on possible interpretations of the existing SSA data, but also on the future observables for the ongoing experiments as well as for planned experiments (such as RHIC II and eRHIC). On the theory side, the talks ranged from overviews and descriptions of the fundamental aspects of SSAs, to presentations of detailed phenomenological studies. All of the talks attracted much interest and initiated active discussions. Directions for future measurements were pointed out, in particular for studies at RHIC. Also, significant theoretical advances were made that may tie together some of the currently proposed mechanisms for single-spin asymmetries. This was a very successful workshop. It stimulated many discussions and new collaborations.
Download or read book Transverse Spin Physics written by Dr. Vincenzo Barone and published by World Scientific. This book was released on 2003 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study deals with the theory and phenomenology of transverse spin effects in high-energy hadronic physics. Contrary to common past belief, it is now rather clear that these effects are far from irrelevant. A decade or so of intense theoretical work has shed much light on the subject and brought to the surface an entire class of new phenomena, which now await thorough experimental investigation. Over the next few years a number of experiments worldwide (at DESY, CERN and Brookhaven) will run with transversely polarised particles, providing data that will enrich our knowledge of the transverse spin structure of hadrons. The principle aim of this work is to assess the state of the art as it stands in 2002. After a few introductory remarks (Chapter 1), in the first part (Chapters 2-4) attention is directed to polarised deep inelastic scattering (DIS), particularly DIS on transversely polarised targets, which probes the transverse spin structure function g2. This structure function is examined within the framework of the quark-parton model and its improvement via perturbative QCD. The existing data are reviewed and commented on (for completeness and comparison, a brief presentation of longitudinally polarised DIS and of the helicity structure of the proton is provided). The second part of the book (Chapters 5-8) focuses on the transverse polarisation of quarks, the so-called "transversity". The partonic content and the QCD evolution of the transversity distributions are presented in detail. The phenomenology of transversity is then studied in the context of Drell-Yan processes and of semi-inclusive lepto- and hadroproduction. The interpretation of data on single-spin asymmetries is discussed and, finally, the prospects for future measurements are reviewed.
Download or read book Foundations of Perturbative QCD written by John Collins and published by Cambridge University Press. This book was released on 2011-04-28 with total page 637 pages. Available in PDF, EPUB and Kindle. Book excerpt: Giving an accurate account of the concepts, theorems and their justification, this book is a systematic treatment of perturbative QCD. It relates the concepts to experimental data, giving strong motivations for the methods. Ideal for graduate students starting their work in high-energy physics, it will also interest experienced researchers.
Download or read book Mon roman policier n 152 written by and published by . This book was released on 1951 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Single Spin Asymmetries in Semi inclusive Deep Inelastic Scattering on a Transversely Polarized Hydrogen Target written by and published by . This book was released on 2004 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Novel Spin Effects in QCD written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements from HERMES, SMC, and Jlab show a significant single-spin asymmetry in semi-inclusive pion leptoproduction [gamma]*(q)p [yields] [pi]X when the proton is polarized normal to the photon-to-pion production plane. Hwang, Schmidt, and I [1] have shown that final-state interactions from gluon exchange between the outgoing quark and the target spectator system lead to such single-spin asymmetries at leading twist in perturbative QCD; i.e., the rescattering corrections are not power-law suppressed at large photon virtuality Q[sup 2] at fixed x[sub bj]. The existence of such single-spin asymmetries (the Sivers effect) requires a phase difference between two amplitudes coupling the proton target with J[sub p][sup z] = [+-] 1/2 to the same final-state, the same amplitudes which are necessary to produce a nonzero proton anomalous magnetic moment. The single-spin asymmetry which arises from such final-state interactions is in addition to the Collins effect which measures the transversity distribution [delta]q(x, Q). The Sivers effect also leads to a leading-twist target single-spin asymmetry for jet production in electroproduction where the thrust axis is used to define the production plane. More generally, Hoyer, Marchal, Peigne, Sannino, and I [2] have shown that one cannot neglect the interactions which occur between the times of the currents in the current correlator even in light-cone gauge. For example, the final-state interactions lead to the Bjorken-scaling diffractive component [gamma]*p [yields] pX of deep inelastic scattering. Since the gluons exchanged in the final state carry negligible k[sup +], the Pomeron structure function closely resembles that of the primary gluon. The diffractive scattering of the fast outgoing quarks on spectators in the target in turn causes shadowing in the DIS cross section. These effects highlight the unexpected importance of final- and initial-state interactions in QCD observables, they lead to leading-twist single-spin asymmetries, diffraction, and nuclear shadowing, phenomena not included in the light-front wavefunctions of the target computed in isolation. Alternatively, as discussed by Belitsky, Ji, and Yuan [3], one can augment the light-front wavefunctions by including the phases induced by initial and final state interactions. Such wave-functions correspond to solving the light-front bound state equation in an external field. Similar initial and final state interactions also lead to Sivers-type single-spin asymmetries in Drell-Yan processes and inclusive hadron reactions such as pp [up-arrow][yields] [pi]X, and heavy quark production, processes which will be important to study in polarized proton experiments at RHIC.
Download or read book Measurement of Single Spin Asymmetries in Semi Inclusive Deep Inelastic Scattering Reaction N u2191 e E X at Jefferson Lab written by and published by . This book was released on 2010 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: What constitutes the spin of the nucleon? The answer to this question is still not completely understood. Although we know the longitudinal quark spin content very well, the data on the transverse quark spin content of the nucleon is still very sparse. Semi-inclusive Deep Inelastic Scattering (SIDIS) using transversely polarized targets provide crucial information on this aspect. The data that is currently available was taken with proton and deuteron targets. The E06-010 experiment was performed at Jefferson Lab in Hall-A to measure the single spin asymmetries in the SIDIS reaction n↑(e, e'?±/K±)X using transversely polarized 3He target. The experiment used the continuous electron beam provided by the CEBAF accelerator with a beam energy of 5.9 GeV. Hadrons were detected in a high-resolution spectrometer in coincidence with the scattered electrons detected by the BigBite spectrometer. The kinematic coverage focuses on the valence quark region, x = 0.19 to 0.34, at Q2 = 1.77 to 2.73 (GeV/c)2. This is the first measurement on a neutron target. The data from this experiment, when combined with the world data on the proton and the deuteron, will provide constraints on the transversity and Sivers distribution functions on both the u and d-quarks in the valence region. In this work we report on the single spin asymmetries in the SIDIS n↑(e, e'?+)X reaction.
Download or read book Measurement of Single Spin Asymmetries in Semi Inclusive Deep Inelastic Scattering Reaction N1 e E Pi sup X at Jefferson Lab written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: What constitutes the spin of the nucleon? The answer to this question is still not completely understood. Although we know the longitudinal quark spin content very well, the data on the transverse quark spin content of the nucleon is still very sparse. Semi-inclusive Deep Inelastic Scattering (SIDIS) using transversely polarized targets provide crucial information on this aspect. The data that is currently available was taken with proton and deuteron targets. The E06-010 experiment was performed at Jefferson Lab in Hall-A to measure the single spin asymmetries in the SIDIS reaction n1!e, e'[pi]{sup ±}/K{sup ±})X using transversely polarized 3He target. The experiment used the continuous electron beam provided by the CEBAF accelerator with a beam energy of 5.9 GeV. Hadrons were detected in a high-resolution spectrometer in coincidence with the scattered electrons detected by the BigBite spectrometer. The kinematic coverage focuses on the valence quark region, x = 0.19 to 0.34, at Q2 = 1.77 to 2.73 (GeV/c)2. This is the first measurement on a neutron target. The data from this experiment, when combined with the world data on the proton and the deuteron, will provide constraints on the transversity and Sivers distribution functions on both the u and d-quarks in the valence region. In this work we report on the single spin asymmetries in the SIDIS n1!e, e'[pi])X reaction.
Download or read book UNIQUE DESCRIPTION FOR SINGLE TRANSVERSE SPIN ASYMMETRIES IN DIS AND HADRONIC COLLISIONS written by F. YUAN and published by . This book was released on 2006 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: We derive a unique formula for the single-transverse-spin asymmetry in semi-inclusive hadron production in deep inelastic scattering, valid for all transverse momentum region. Based on this, we further study the integrated asymmetry weighted with transverse-momentum. They can be evaluated in terms of the twist-three quark-gluon correlation functions, which are responsible for the single spin asymmetry in single inclusive hadron production in hadronic collisions. By using the fitted twist-three functions from the hadronic collision data, we find a consistent description for SSAs in deep inelastic scattering. This demonstrates that we have a unique picture for SSAs in these two processes, and shall provide important guidelines for future studies.
Download or read book Single Spin Asymmetries in L P transv Pol H X Processes and Transverse Momentum Dependent Factorization written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Some estimates for the transverse Single Spin Asymmetry, A_N, in the inclusive processes l p(transv. Pol.) --> h X, given in a previous paper, are expanded and compared with new experimental data. The predictions are based on the Sivers distributions and the Collins fragmentation functions which fit the azimuthal asymmetries measured in Semi-Inclusive Deep Inelastic Scattering (SIDIS) processes (l p(transv. Pol.) --> l' h X). The factorisation in terms of Transverse Momentum Dependent distribution and fragmentation functions (TMD factorisation) -- i.e., the theoretical framework in which SIDIS azimuthal asymmetries are analysed -- is assumed to hold also for the inclusive process l p --> h X at large P_T. The values of A_N thus obtained agree in sign and shape with the data. Some predictions are given for future experiments.
Download or read book Deep Inelastic Scattering written by Masahiro Kuze and published by World Scientific. This book was released on 2007 with total page 996 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings present the most up-to-date status of deep inelastic scattering (DIS) physics. Topics such as structure function measurements and phenomenology, quantum chromodynamics (QCD) studies in DIS and photoproduction, spin physics and diffractive interactions are reviewed in detail, with emphasis on those studies that push the test of QCD and the Standard Model to the limits of their present range of validity, towards both the very high and the very low four-momentum transfers in lepton-proton scattering.
Download or read book Single Spin Asymmetries in Charged Pion Production from Semi Inclusive Deep Inelastic Scattering on a Transversely Polarized 3 He Target written by and published by . This book was released on 2011 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: We report the first measurement of target single spin asymmetries in the semi-inclusive $^3{He}(e, e'\pi^\pm)X$ reaction on a transversely polarized target. The experiment, conducted at Jefferson Lab using a 5.9 GeV electron beam, covers a range of 0.14 $
Download or read book Deep Inelastic Scattering Proceedings Of The 8th International Workshop written by John A Gracey and published by World Scientific. This book was released on 2001-02-22 with total page 774 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume focusses on four main topics: structure functions, tests of quantum chromodynamics, physics at the highest Q2 and p2T, and high energy scattering and diffraction. Comprehensive review articles on hadronic and photon structure, lepton-parton and parton-parton physics as well as future experimental opportunities are presented, together with a special lecture on HERA's legacy after the first decade of operation.
Download or read book The Sivers Effect and the Single Spin Asymmetry A N in P transv Pol P H X Processes written by and published by . This book was released on 2013 with total page 54035 pages. Available in PDF, EPUB and Kindle. Book excerpt: The single spin asymmetry A_N, for large P_T single inclusive particle production in p(transv. pol.) p collisions, is considered within a generalised parton model and a transverse momentum dependent factorisation scheme. The focus is on the Sivers effect and the study of its potential contribution to A_N, based on a careful analysis of the Sivers functions extracted from azimuthal asymmetries in semi-inclusive deep inelastic scattering processes. It is found that such Sivers functions could explain most features of the A_N data, including some recent STAR results which show the persistence of a non zero A_N up to surprisingly large P_T values.
Download or read book Predictions for Sivers Single Spin Asymmetries in One and Two hadron Electroproduction at CLAS12 and EIC written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of the Sivers effect, describing correlations between the transverse polarization of the nucleon and its constituent (unpolarized) parton's transverse momentum, has been the topic of a great deal of experimental, phenomenological and theoretical effort in recent years. Semi-Inclusive Deep Inelastic Scattering measurements of the corresponding single spin asymmetries (SSA) at the upcoming CLAS12 experiment at JLab and the proposed Electron-Ion Collider will help to pinpoint the flavor structure and the momentum dependence of the Sivers parton distribution function describing this effect. Here we describe a modified version of the $\tt{PYTHIA}$ Monte Carlo event generator that includes the Sivers effect. Then we use it to estimate the size of these SSAs, in the kinematics of these experiments, for both one and two hadron final states of pions and kaons. For this purpose we utilize the existing Sivers parton distribution function (PDF) parametrization extracted from HERMES and COMPASS experiments. We also show that the the leading order approximation commonly used in such extractions provides significantly underestimated values of Sivers PDFs, as the omitted parton showers and non-DIS processes play an important role in these SSAs at lower light-cone momentum fraction, for example in the COMPASS kinematics.
Download or read book Hadron Physics written by T. Bressani and published by IOS Press. This book was released on 2005-07-29 with total page 707 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume of the International School of Physics Enrico Fermi is dedicated to Valerio Filippini. He devoted his life to physics. Valerio Filippini was born in Somma Lombardo (Milano) on December 8, 1958. He obtained the Master Degree in Physics at the University of Pavia in 1982, cum laude. After a working parenthesis at an industrial firm, he became Research Physicist of INFN, Sezione di Pavia, in 1988 and was promoted Senior Research Physicist in 1993. He participated to the experiments PS 179 (TOFRADUPP) and PS 201 (Obelix) at LEAR (CERN), FINUDA at LNF and ATHENA at AD (CERN). His outstanding scientific contributions were provided in the OBELIX and FINUDA experiments. Nobody could compete with Filippini in exploiting at best the daily-evoluting performances of the computing tools for the needs of the experiments, both for on-line and off-line purposes. The FINUDA experiment collected physics data immediately after the roll-in thanks to the reliability and simplicity of the on-line system designed and assembled by the physicist. However, he was not only a 'Clavier Physicist' but a complete Scientist: he also leaded the Pavia Group in designing and providing advanced detectors, and in developing mathematical methods for the analysis of the data. His scientific contributions are documented by about 90 publications on refereed international journals, about 100 contributions to International Conferences and Workshops, and 3 invited talks.
