Download or read book Heavy Quark Production in CC and NC DIS and the Structure of Real and Virtual Photons in NLO QCD written by Ingo Schienbein and published by . This book was released on 2001 with total page 199 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Heavy quark Physics in Quantum Chromodynamics written by and published by . This book was released on 1991 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heavy quarks can expose new symmetries and novel phenomena in QCD not apparent in ordinary hadronic systems. In these lectures I discuss the use of effective-Lagrangian and light-cone Fock methods to analyze exclusive heavy hadron decays such as [Upsilon] → p{bar p} and B → [pi][pi], and also to derive effective Schroedinger and Dirac equations for heavy quark systems. Two contributions to the heavy quark structure functions of the proton and other light hadrons are identified: an extrinsic'' contribution associated with leading twist QCD evolution of the gluon distribution, and a higher twist intrinsic'' contribution due to the hardness of high-mass fluctuations of multi-gluon correlations in hadronic wavefunctions. A non-perturbative calculation of the heavy quark distribution of a meson in QCD in one space and one time is presented. The intrinsic higher twist contributions to the pion and proton structure functions can dominate the hadronic production of heavy quark systems at large longitudinal momentum fraction x{sub F} and give anomalous contributions to the quark structure functions of ordinary hadrons at large x{sub bj}. I also discuss a number of ways in which heavy quark production in nuclear targets can test fundamental QCD phenomena and provide constraints on hadronic wavefunctions. The topics include color transparency, finite formation time, and predictions for charm production at threshold, including nuclear-bound quarkonium. I also discuss a number of QCD mechanisms for the suppression of J/[psi] and [Upsilon] production in nuclear collisions, including gluon shadowing, the peripheral excitation of intrinsic heavy quark components at large x{sub F}, and the coalescence of heavy quarks with co-moving spectators at low x{sub F}.
Download or read book Heavy Quark Production Processes in QCD written by and published by . This book was released on 1984 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have identified two novel effects in QCD, each of which acts to enhance the production of heavy quark and supersymmetric particles beyond what is conventionally expected from gluon fusion. Both effects are present in QED, but are compounded in QCD because of the increased number of diagrams and the much larger coupling constant. The intrinsic charm quark distribution in the nucleon could account for the observed enhancements of the charm structure function at large x and features of the charm production data but this mechanism is relatively suppressed for heavier systems. Prebinding distortion of the fusion cross section is, however, likely to be significant for the production at low p/sub T/ of all particles containing heavy colored constituents. At this stage the QCD calculations are highly model dependent although they agree with the general properties which can be inferred from the operator product expansion in the heavy quark mass. Much more theoretical analysis of these effects is clearly needed. It is also clear that much more experimental work is necessary to extend and confirm the reported anomalous heavy quark signals. 22 references.
Download or read book Heavy Quark Production in Perturbative QCD at HERA written by Xiaoning Wang and published by . This book was released on 1998 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Global QCD Analysis and Parton Structure of the Nucleon written by Hung-Liang Lai and published by . This book was released on 1997 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book QCD Mechanisms for Heavy Particle Production written by and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: For very large pair mass, the production of heavy quarks and supersymmetric particles is expected to be governed by ACD fusion subprocesses. At lower mass scales other QCD mechanisms such as prebinding distortion and intrinsic heavy particle Fock states can become important, possibly accounting for the anomalies observed for charm hadroproduction. We emphasize the importance of final-state Coulomb interactions at low relative velocity in QCD and predict the existence of heavy narrow four quark resonances (c c-bar u u-bar) and (cc c-bar c-bar) in .gamma gamma. reactions. Coherent QCD contributions are discussed as a contribution to the non-additivity of nuclear structure functions and heavy particle production cross sections. We also predict a new type of amplitude zero for exclusive heavy meson pair production which follows from the tree-graph structure of QCD. 35 refs., 8 figs., 1 tab.
Download or read book Challenges to Quantum Chromodynamics written by and published by . This book was released on 1989 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt: The general structure of QCD meshes remarkably well with the facts of the hadronic world, especially quark-based spectroscopy, current algebra, the approximate point-like structure of large momentum transfer inclusive reactions, and the logarithmic violation of scale invariance in deep inelastic lepton-hadron reactions. QCD has been successful in predicting the features of electron-positron and photon-photon annihilation into hadrons, including the magnitude and scaling of the cross sections, the shape of the photon structure function, the production of hadronic jets with patterns conforming to elementary quark and gluon subprocesses. The experimental measurements appear to be consistent with basic postulates of QCD, that the charge and weak currents within hadrons are carried by fractionally-charged quarks, and that the strength of the interactions between the quarks, and gluons becomes weak at short distances, consistent with asymptotic freedom. Nevertheless in some cases, the predictions of QCD appear to be in dramatic conflict with experiment. The anomalies suggest that the proton itself as a much more complex object than suggested by simple non-relativistic quark models. Recent analyses of the proton distribution amplitude using QCD sum rules points to highly-nontrival proton structure. Solutions to QCD in one-space and one-time dimension suggest that the momentum distributions of non-valence quarks in the hadrons have a non-trival oscillatory structure. The data seems also to be suggesting that the intrinsic'' bound state structure of the proton has a non- negligible strange and charm quark content, in addition to the extrinsic'' sources of heavy quarks created in the collision itself. 144 refs., 46 figs., 2 tabs.
Download or read book Heavy Quark Associated Production with One Hard Photon at Hadron Colliders written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present the calculation of heavy-quark associated production with a hard photon at hadron colliders, namely $pp(p\bar p) \rightarrow Q\bar Q\gam +X$ (for $Q=t, b$), at Next-to-Leading Order (NLO) in Quantum Chromodynamics (QCD). We study the impact of NLO QCD corrections on the total cross section and several differential distributions at both the Tevatron and the Large Hadron Collider (LHC). For $t\bar t\gam$ production we observe a sizeable reduction of the renormalization and factorization scale dependence when the NLO QCD corrections are included, while for $b\bar b\gam$ production a considerable scale dependence still persists at NLO in QCD. This is consistent with what emerges in similar processes involving $b$ quarks and vector bosons and we explain its origin in detail. For $b\bar b\gam$ production we study both the case in which at least one $b$ jet and the case in which at least two $b$ jets are observed. We perform the $b\bar b\gam$ calculation using the Four Flavor Number Scheme (4FNS) and compare the case where at least one $b$ jet is observed with the corresponding results from the Five Flavor Number Scheme (5FNS) calculation. Finally we compare our results for $p\bar p \rightarrow \gam+b+X$ with the Tevatron data.
Download or read book QCD Perspectives on Hot and Dense Matter written by Jean-Paul Blaizot and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 526 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many facets of quantum chromodynamics (QCD) are relevant to the in-depth discussion of theoretical and experimental aspects of high-energy nucleus-nucleus collisions. Exciting phenomena are being discovered in such ultrarelativistic heavy ion collisions, notably the increasingly important role of deconfined quark-gluon matter created in the early stage. The book contains lectures on the physics of hot dense matter, the expected phase transitions and colour superconductivity, recent developments in the treatment of nonlinear effects at large parton densities, fundamental issues in the phenomenology of ultrarelativistic heavy collisions. The latest data on heavy ion collisions are also presented. A unique collection of lectures on the many facets of QCD relevant to the physics of hot dense matter.
Download or read book Hadron Collider Physics 2005 written by Mario Campanelli and published by Springer Science & Business Media. This book was released on 2007-08-17 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gathers the proceedings of The Hadron Collider Physics Symposia (HCP) 2005, and reviews the state-of-the-art in the key physics directions of experimental hadron collider research. Topics include QCD physics, precision electroweak physics, c-, b-, and t-quark physics, physics beyond the Standard Model, and heavy ion physics. The present volume serves as a reference for everyone working in the field of accelerator-based high-energy physics.
Download or read book Monte Carlo Generators for HERA Physics written by A. T. Doyle and published by . This book was released on 1999 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The QCD Vacuum Hadrons and the Superdense Matter written by E. V. Shuryak and published by World Scientific. This book was released on 1988 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is probably the only textbook available that gathers QCD, many-body theory and phase transitions in one volume. The presentation is pedagogical and readable. It provides materials interesting to both students and researchers of astrophysics, nuclear physics and high energy physics.
Download or read book Discovery of Single Top Quark Production written by Dag Gillberg and published by Springer Science & Business Media. This book was released on 2011-01-22 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark is by far the heaviest known fundamental particle with a mass nearing that of a gold atom. Because of this strikingly high mass, the top quark has several unique properties and might play an important role in electroweak symmetry breaking—the mechanism that gives all elementary particles mass. Creating top quarks requires access to very high energy collisions, and at present only the Tevatron collider at Fermilab is capable of reaching these energies. Until now, top quarks have only been observed produced in pairs via the strong interaction. At hadron colliders, it should also be possible to produce single top quarks via the electroweak interaction. Studies of single top quark production provide opportunities to measure the top quark spin, how top quarks mix with other quarks, and to look for new physics beyond the standard model. Because of these interesting properties, scientists have been looking for single top quarks for more than 15 years. This thesis presents the first discovery of single top quark production. It documents one of the flagship measurements of the D0 experiment, a collaboration of more than 600 physicists from around the world. It describes first observation of a physical process known as “single top quark production”, which had been sought for more than 10 years before its eventual discovery in 2009. Further, his thesis describes, in detail, the innovative approach Dr. Gillberg took to this analysis. Through the use of Boosted Decision Trees, a machine-learning technique, he observed the tiny single top signal within an otherwise overwhelming background. This Doctoral Thesis has been accepted by Simon Fraser University, Burnaby, BC, Canada.
Download or read book Proceedings of the Sixteenth Rencontre de Moriond QCD and lepton physics written by J. Thanh Van Tran and published by Atlantica Séguier Frontières. This book was released on 1981 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quark Confinement And The Hadron Spectrum V Proceedings Of The 5th International Conference written by Nora Serafina Brambilla and published by World Scientific. This book was released on 2003-08-27 with total page 551 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an update on our understanding of strong interaction, with theoretical and experimental highlights included. It is divided into five sections. The first section is devoted to the investigations into and the latest results on the mechanism of quark confinement. The second and third sections focus respectively on light and heavy quarks (effective field theories, Schwinger-Dyson approach and lattice QCD results). The fourth section deals with the deconfinement mechanism and quark-gluon plasma formation signals. The last section presents highlights of experiments, new physics beyond QCD, and nonperturbative approaches in other theories (strings and SUSY) that may be useful in QCD.
Download or read book Higher Order QCD Corrections to Single Top Quark Production written by Mohammad Assadsolimani and published by disserta Verlag. This book was released on 2014-08 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is known that the LHC has a considerable discovery potential because of its large centre-of-mass energy (vs =14 TeV) and the high design luminosity. In addition, the two experiments ATLAS and CMS perform precision measurements for numerous models in physics. The increasing experimental precision demands an even higher level of accuracy on the theoretical side. For a more precise prediction of outcomes, one has to consider the corrections obtained typically from Quantum Chromodynamics (QCD). The calculation of these corrections in the high energy regime is described by perturbation theory. In the present study, multi-loop calculations in QCD, including in particular two-loop corrections for single top quark production, are considered. There are several phenomenological motivations to study single top quark production: Firstly, the process is sensitive to the electroweak Wtb-vertex; moreover, non-standard couplings can hint at physics beyond the Standard Model. Secondly, the t-channel cross section measurement provides information on the b-quark Parton Distribution Functions (PDF). Finally, single top quark production enables us to directly measure the Cabibbo-Kobayashi-Maskawa(CKM) matrix element Vtb. The next-to-next-to-leading-order (NNLO) calculation of the single top quark production has many building blocks. In this study, two blocks will be presented: one-loop corrections squared and two-loop corrections interfered with Born. Initially, the one-loop squared contribution at NNLO for single top quark production will be calculated. Before we begin with the calculation of the two-loop corrections to single top quark production, we calculate the QCD form factors of heavy quarks at NNLO, along with the axial vector coupling as a first independent check. A comparison with the relevant literature suggests that this approach is in line with generally accepted procedure. This consistency check provides a proof of the validity of our setup. In the next step, the two-loop corrections to single top quark production will be calculated. After reducing all occurring tensor integrals to scalar integrals, we apply the integration by parts method (IBP) to find the master integrals. This step is a major challenge compared to all similar calculations because of the number of variables in the problem (two Mandelstam variables s and t, the dimension d and the mass of the top quark mt as well as the mass of the W boson mw). Finally, the calculation of the three kinds of topologies – vertex corrections, double boxes and non-planar double boxes – in the two-loop contribution at NNLO calculation will be presented.
Download or read book Heavy Quark Production in QCD written by and published by . This book was released on 1988 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt:
