DOCSLIB.ORG

KEK-79-14 July 1979 TRISTAN PHOTOPRODUCTION at TRISTAN

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
KEK-79-14 July 1979 TRISTAN PHOTOPRODUCTION at TRISTAN KEK-79-14 July 1979 TRISTAN PHOTOPRODUCTION AT TRISTAN ENERGY K. Ishida, T. ICobayashi and T. Yoshino NATIONAL LABORATORY FOR HIGH ENERGY PHYSICS OHO-MACHI, TSUKUBA-GUN 1BARAKI, JAPAN KEK Reports are available from Technical Information Office National Laboratory for High Energy Physics Oho-machi, Tsukuba-gun Ibaraki-ken, 300-32 JAPAN Phone: 0298-64-1171 Telex: 3652-534 (Domestic) (0)3652-534 (International) Cable: KEK0H0 Photoproduction at TRISTAN Energy K. Ishida, T. Kobayashi and T. Yoshino Department of Physics Tokyo Metropolitan University Fukazawa, Setagaya, Tokyo 158 Japan Abstract Focussing our attention upon the structure of photon we discuss its complementary aspects represented by the vector meson dominance (VMD) and the perturbative quantum chromo- dynamics (QCD). Photoproduction of vector mesons and that of large transverse momentum jets are studied as testing ground for two aspects, in the energy range of TRISTAN (Ee- x Ep2:20 GeV x 300 GeV). It is found that Vector Mesons of mass up to ~ 10 GeV will be produced more than once per day for tagged photons. Large- p^ jet production is found rather copious and it can be a good probe to study the photon structure function predicted from QCD. SI. Introduction New energy range to be explored by coining very big accelerators would force us to concentrate our attention on very fundamental and unified aspects of high energy interactions. The Weinberg-Salam model ^ has succeeded in unifying electro­ magnetic and weak interactions while quantum chromodynamics CQCD) ' has become a prime candidate for the theory of strong +) interactions. In this respect TRISTAN project, an electron- proton colliding beam facility produced in KEK, will bring us valuable informations both on weak and strong interactions. While much attention has been paid on deep-inelastic lepton scattering, very high energy photoproduction will also provide us another important source of interactions. In this report we shall concentrate ourselves on studying the structure of photons at the TRISTAN energies; the laboratory momenta of colliding electron and proton are 20 and 300 GeV, respectively, and the luminocity of taggedT- P collision is 'vl029/cm2-sec. We are very much concerned about how photon manifests itself through interactions with other particles, particularly, with hadrons. It is widely accepted that the vector meson dominance model (VMD)3) provides a useful and successful description of low momentum transfer reactions. This implies that the photon has very similar internal structure to that of hadrons.*' Does this persist in higher energies? In the events with large transverse momentum hadrons, on the other hand, the process should be governed by the short distance mechanism and one might naively expect a point-like coupling of the photon with partons to dominate the cross sections. The perturbative QCD tells us, however, that the photon should also have internal quark structure which is calculable with the help of the renomalization group (RG)-equations. ' Photoproduction of large-Px jets will thus he useful to probe the photon structure predicted from QCD. In the present report we attempt our preliminary first step toward a unified understanding of the photon structure which should be revealed in future. If QCD is the correct theory of strong interactions, perturbative and nonperturbative (VMD) aspects will finally be unified as a complementary entity like resonance and Regge behaviors in the duality. It is our expectation that this ambitious program may gradually be realized through studies of high energy photoproduction process. In J 2 we show predictions of the VMD on the total photon- proton cross section and on vector meson production. These investigation will give a simple criterion for the validity of the VMD. Section 3 deals with the high-p^ jet production in photon-proton collisions in the framework of the perturbative QCD. At TRISTAN, the colliding beam facility of 300 GeV proton and photons from the 20 GeV electrons, enable us to carry out various kinds of interesting experiments. Some topics other than those described in $ 2 and § 3 are briefly mentioned in|4. Photoproduction data are obtained from ep collisions in the limit of small momentum transfer, say, Q 2 < m£2. For actual calculations - 3 - we neglect this small Q values and assume it to be equal to zero. The effective luminosity of tagged-photon proton collisions will thus be two-orders of magnitude smaller than that of electron-proton collisions. $2. Hadronic Behavior of Photons The vector meson dominance model (VMD) has been successful in describing various aspects of photoproduction processes at small momentum transfers in the presently available photon energy region. In order to get the first clue to phenomena in yet unattainable high energy region a simple extrapolation of the existing model may be useful. In this section we extrapolate the predictions of the VMD to the TRISTAN energy range. This kind of calculations were already done by others in planning the future projects. ' We will, however, make some improvement on several respects. 2.1. Total Photon Cross Section on Protons It has been well known that the total photon cross section on proton ( fli^ ) shows the remarkable similarity to the pion- nucleon total cross section apart from the overall normalization. This strongly suggests that the vector meson dominance (VMD] mechanism would be responsible for a major part of the total cross section. It is of great interest to see whether or not the similarity holds in the TRISTAN energy range (s < 24,000 GeV ) which is far beyond the one presently available. The total photon cross section on proton can be written in the VMD as t(s) = i) °# f T^;crvt,(s) c, Here & (= 1/137) is the fine structure constant of QED, s being the total center of mass energy squared, OTWs) and VL. are the vector meson-proton total cross section and the photon-vector meson coupling constant, respectively. We assume that the sum over vector mesons Z extends over f, to , 0 , and J/ty-. V Additive quark model is used for the Vector Meson total cross sections of proton. Figure 1 shows the result. At the maximum TRISTAN energy we have Oifli^^" ,1D' *^w e comPare our result with the total cross section at presently available energy (Ey Js. 180 GeV) ' the rising behavior seems to be rather slow. Our moderate energy dependence is attributed to the slowly rising asymptotic cross sections parametrized •" as a + b In s. If a new quark flavor is produced above certain threshold energy, it is expected that trt the total cross section (Sip will show an abnormal rise at the threshold. Whether such a behavior can be 3een or not remains an open question. 2.2. Vector Meson Photoproduction Since the vector mesons have the same quantum number JPC = l"~ as the photon they are diffractively produced at high energies as shown in Fig. 2. Then we expect new heavy vector - S mesons to be diffractively produced copiously at TRISTAN. The VMD idea is also useful here. The total cross section for r + p —»V + P can he written as 9^ where By denotes the slope parameter of the differential cross section appearing in at vdt k^z^J^ andQvp(s), the total cross section of Vp collisions. Here t represents the usual momentum transfer squared and t . is its kinematically allowable minimum. For light Vector mesons if,CO , <f>, J/ijr) we adopt the same G7p(s) as those used in evaluating eq. C2.1). For the slope parameter we examine two altarnatives: (a) Bv = const. 2 2 2 4) = Bu=i 7.5 GeV' , BBff ==££ 5.5.55 GeGeV"V , BBJ/(J/(.. ::xx 2.2.00 GeV"GeV (b) Bv(s) = bT + 2 (X'finCs/sc). Here bv = Bv - 2'a'€nC50/so] , 1 K ~ 0.2 is the pbmeron slope ' and s0 is the scale parameter f set equal to 1 GeV . Shown in figure 3 are the VMD estimates of the total photoproduction cross sections of light vector mesons plotted against s. In estimating heavy vector meson production cross sections beyond the J/iJ-, we have to be careful because of too many unknown factors. Nevertheless, some reasonable assumptions allow us to evaluate the production yields. First we have to properly take into account the threshold behavior. As the simplest form we adopt the parametrization for the J/$|r photoproduction used by Thorndike •*, 4) where sth and s0 are, respectively, the threshold of the heavy vector meson and the appropriate mass scale. We find that the choice s o " sth =; 7.5 m* can reproduce both J/^r and $ photoproduction threshold behavior. Empirically, we have '' ' 12, > which works reasonably well. After passing over the steep rise in the threshold region, the cross section is leveled off and follows the behavior of that of light vector mesons. As for the slope parameter we also examine two cases (a) Bv = Bjt^ 2 2 = ZGeV" and (b) By(s) = Bj^ +2tf £n(s/s0), ft' being 0.2 GeV" . In fig. 4, we show energy dependence of the production cross sections of T and VCtf). The cross section of }T photo­ production' at s 2£20,000 GeV can be read - 7 - The use of untagged photons probably increases the yield by about two-orders of magnitude. The counting rate of V[tt) heavier than 20 GeV, however, is too low to be observed even at the highest TRISTAN energy. 2.5. Pseudoscalar Meson Production via Primakoff Effect Another interesting photoproduction process is the Primakoff production of a new even-charge conjugation states with J * 1 composed of new quark flavors, especially, pseudscalar partners of heavy vector mesons. Shown in Fig- 5 is the schematic illustration of the production process Y+ P -*x * p followed by the decay X-+YY.
Load more

Recommended publications
  • Vector Mesons and an Interpretation of Seiberg Duality
    Vector Mesons and an Interpretation of Seiberg Duality Zohar Komargodski School of Natural Sciences Institute for Advanced Study Einstein Drive, Princeton, NJ 08540 We interpret the dynamics of Supersymmetric QCD (SQCD) in terms of ideas familiar from the hadronic world. Some mysterious properties of the supersymmetric theory, such as the emergent magnetic gauge symmetry, are shown to have analogs in QCD. On the other hand, several phenomenological concepts, such as “hidden local symmetry” and “vector meson dominance,” are shown to be rigorously realized in SQCD. These considerations suggest a relation between the flavor symmetry group and the emergent gauge fields in theories with a weakly coupled dual description. arXiv:1010.4105v2 [hep-th] 2 Dec 2010 10/2010 1. Introduction and Summary The physics of hadrons has been a topic of intense study for decades. Various theoret- ical insights have been instrumental in explaining some of the conundrums of the hadronic world. Perhaps the most prominent tool is the chiral limit of QCD. If the masses of the up, down, and strange quarks are set to zero, the underlying theory has an SU(3)L SU(3)R × global symmetry which is spontaneously broken to SU(3)diag in the QCD vacuum. Since in the real world the masses of these quarks are small compared to the strong coupling 1 scale, the SU(3)L SU(3)R SU(3)diag symmetry breaking pattern dictates the ex- × → istence of 8 light pseudo-scalars in the adjoint of SU(3)diag. These are identified with the familiar pions, kaons, and eta.2 The spontaneously broken symmetries are realized nonlinearly, fixing the interactions of these pseudo-scalars uniquely at the two derivative level.
    [Show full text]
  • Tests of Perturbative Quantum Chromodynamics in Photon-Photon
    SLAC-PUB-2464 February 1980 MAST, 00 TESTS OF PERTURBATIVE QUANTUM CHROMODYNAMICS IN PROTON-PHOTON COLLISIONS Stanley J. Brodsky Stanford Linear Accelerator Center Stanford University, Stanford, California 94305 ABSTRACT The production of hadrons in the collision of two photons via the process e e -*- e e X (see Fig. 1) can provide an ideal laboratory for testing many of the features of the photon's hadronic interactions, especially its short distance aspects. We will review here that part of two-photon physics which is particularly relevant to testa of pert":rh*_tivt QCD. (Invited talk presented at the 1979 International Conference- on Two Photon Interactions, Lake Tahoe, California, August 30 - September 1, 1979, Sponsored by University of California, Davis.) * Work supported by the Department of Energy under contract number DE-AC03-76SF00515. •• LIMITED e+—=>—<t>w(_ JVMS^A,—<e- x, ^ ^ *2 „-78 cr(yr — hadrons) 3318A1 Fig. 1. Two-photon annihilation into hadrons in e e collisions. 2 7 Large PT let production " Perhaps the most interesting application of two photon physics to QCD is the production of hadrons and hadronic jets at large p . The elementary reaction YY "*" *1^ "*" hadrons yields an asymptotically scale- invariant two-jet cross section at large p„ proportional to the fourth power of the quark charge. The yy -*• qq subprocess7 implies the produc­ tion of two non-collinear, roughly coplanar high p (SPEAR-like) jets, with a cross section nearly flat in rapidity. Such "short jets" will be readily distinguishable from e e -*• qq events due to missing visible energy, even without tagging the forward leptons.
    [Show full text]
  • Photon Structure Functions at Small X in Holographic
    Physics Letters B 751 (2015) 321–325 Contents lists available at ScienceDirect Physics Letters B www.elsevier.com/locate/physletb Photon structure functions at small x in holographic QCD ∗ Akira Watanabe a, , Hsiang-nan Li a,b,c a Institute of Physics, Academia Sinica, Taipei, 115, Taiwan, ROC b Department of Physics, National Tsing-Hua University, Hsinchu, 300, Taiwan, ROC c Department of Physics, National Cheng-Kung University, Tainan, 701, Taiwan, ROC a r t i c l e i n f o a b s t r a c t Article history: We investigate the photon structure functions at small Bjorken variable x in the framework of the Received 20 February 2015 holographic QCD, assuming dominance of the Pomeron exchange. The quasi-real photon structure Received in revised form 9 October 2015 functions are expressed as convolution of the Brower–Polchinski–Strassler–Tan (BPST) Pomeron kernel Accepted 26 October 2015 and the known wave functions of the U(1) vector field in the five-dimensional AdS space, in which the Available online 29 October 2015 involved parameters in the BPST kernel have been fixed in previous studies of the nucleon structure Editor: J.-P. Blaizot functions. The predicted photon structure functions, as confronted with data, provide a clean test of the Keywords: BPST kernel. The agreement between theoretical predictions and data is demonstrated, which supports Deep inelastic scattering applications of holographic QCD to hadronic processes in the nonperturbative region. Our results are also Gauge/string correspondence consistent with those derived from the parton distribution functions of the photon proposed by Glück, Pomeron Reya, and Schienbein, implying realization of the vector meson dominance in the present model setup.
    [Show full text]
  • Photon Structure Function Revisited
    Journal of Modern Physics, 2015, 6, 1023-1043 Published Online July 2015 in SciRes. http://www.scirp.org/journal/jmp http://dx.doi.org/10.4236/jmp.2015.68107 Photon Structure Function Revisited Christoph Berger I. Physikalisches Institut, RWTH Aachen University, Aachen, Germany Email: [email protected] Received 2 June 2015; accepted 7 July 2015; published 10 July 2015 Copyright © 2015 by author and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract The flux of papers from electron positron colliders containing data on the photon structure func- γ 2 tion F2 ( xQ, ) ended naturally around 2005. It is thus timely to review the theoretical basis and confront the predictions with a summary of the experimental results. The discussion will focus on the increase of the structure function with x (for x away from the boundaries) and its rise with lnQ2 , both characteristics being dramatically different from hadronic structure functions. The agreement of the experimental observations with the theoretical calculations is a striking success of QCD. It also allows a new determination of the QCD coupling constant α S which very well cor- responds to the values quoted in the literature. Keywords Structure Functions, Photon Structure, Two Photon Physics, QCD, QCD Coupling Constant 1. Historical Introduction The notion that hadron production in inelastic electron photon scattering can be described in terms of structure functions like in electron nucleon scattering is on first sight surprising because photons are pointlike particles whereas nucleons have a radius of roughly 1 fm.
    [Show full text]
  • A Remark on Vector Meson Dominance, Universality and the Pion Form Factor
    Vol. 38 (2007) ACTA PHYSICA POLONICA B No 6 A REMARK ON VECTOR MESON DOMINANCE, UNIVERSALITY AND THE PION FORM FACTOR Alfonso R. Zerwekh Instituto de Física, Facultad de Ciencias, Universidad Austral de Chile Casilla 567, Valdivia, Chile [email protected] (Received December 1, 2006) In this paper, we address the universality problem in the mass-mixing representation of vector meson dominance. First, we stress the importance of using physical (mass eigenstate) fields in order to get the correct q2 dependence of the pion form factor. Then we show that, when a direct coupling of the (proto-)photon to the pions is included, it is not necessary to invoke universality. Our method is similar to the delocalization idea in some deconstruction theories. PACS numbers: 12.40.Vv, 13.40.Gp, 14.40.Aq In 1960 Sakurai [1] proposed a theory of strong interactions based on the idea of local gauge invariance, where the interaction was supposed to be mediated by vector mesons. In this scenario, the electromagnetic interaction of hadrons was introduced through a mixing of the photon and the vector mesons. This idea is known as Vector Meson Dominance (VMD) [2]. Historically, two Lagrangian realizations of VMD have been in use. The first one, due to Kroll, Lee and Zumino [3], describes the mixing of the photon and the rho meson through a term of the form e µν Lγρ = ρµν F . (1) 2gρ This representation is usually called VMD-1. In general, it is viewed as the more elegant VMD realization because it is explicitly consistent with electromagnetic gauge invariance and the pion form factor calculated from it can be written as q2 g F q2 − ρππ , π( )= 1 2 − 2 (2) q mρ gρ (2077) 2078 A.R.
    [Show full text]
  • Final Report RESEARCH and INNOVATION DG
    EUROPEAN COMMISSION Final Report RESEARCH AND INNOVATION DG Project No: 283286 Project Acronym: HadronPhysics3 Project Full Name: Study of Strongly Interacting Matter Final Report Period covered: from 01/01/2012 to 31/12/2014 Date of preparation: 03/08/2015 Start date of project: 01/01/2012 Date of submission (SESAM): 07/10/2015 Project coordinator name: Project coordinator organisation name: Dr. Carlo Guaraldo ISTITUTO NAZIONALE DI FISICA NUCLEARE Version: 2 Final Report PROJECT FINAL REPORT Grant Agreement number: 283286 Project acronym: HadronPhysics3 Project title: Study of Strongly Interacting Matter Funding Scheme: FP7-CP-CSA-Infra Project starting date: 01/01/2012 Project end date: 31/12/2014 Name of the scientific representative of the Dr. Carlo Guaraldo ISTITUTO NAZIONALE DI project's coordinator and organisation: FISICA NUCLEARE Tel: +39 06 94032318 Fax: +39 06 94032559 E-mail: [email protected] Project website address: http://www.hadronphysics3.eu Project No.: 283286 Page - 2 of 326 Period number: 2nd Ref: 283286_HadronPhysics3_Final_Report-12_20151007_154307_CET.pdf Final Report Please note that the contents of the Final Report can be found in the attachment. 4.1 Final publishable summary report Executive Summary The HadronPhysics3 project, building on two previous HadronPhysics projects, is strongly anchored within the community of virtually all the European researchers working on hadron physics and strong interactions. More than 50 European institutions and over 2500 European scientists, active in Universities and Research Organizations, have joined forces to provide transnational access to five European hadron facilities. Nine structured networking opportunities, plus the management of the project, and fourteen joint research activities (JRAs), further support the integration of experimental and theoretical research.
    [Show full text]
  • Electromagnetic Scattering of Vector Mesons in the Sakai-Sugimoto Model
    Electromagnetic scattering of vector mesons in the Sakai-Sugimoto model C. A. Ballon Bayona Centre for Particle Theory, University of Durham, Science Laboratories, South Road, Durham DH1 3LE { United Kingdom email: [email protected] Henrique Boschi-Filho, Nelson R. F. Braga, Marcus A. C. Torres Instituto de F´ısica, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, RJ 21941-972 { Brazil emails: [email protected], [email protected], [email protected] Abstract In this proceeding we review some of our recent results for the vector meson electromagnetic form factors and structure functions in the Sakai-Sugimoto model. The latter is a string model that describes many features of the non- perturbative regime of Quantum Chromodynamics in the large Nc limit. 1 Introduction It was shown by 't Hooft in 1973 [1] that considering the large Nc limit of Quantum Chromodynamics (QCD) the amplitudes simplify and we can treat 1=Nc as a parameter for perturbative expansions. Moreover, the Feynman diagrams can be redrawn as surfaces with different topologies so that the 1=Nc expansion is interpreted as an expansion in the genus of the surfaces. The 't Hooft approach is known as large Nc QCD and the genus expansion is similar to the one that arises in String Theory suggesting a duality between quantum field theories and string theories. arXiv:1111.1658v2 [hep-th] 29 Aug 2012 The first concrete duality between quantum field theories and string theo- ries was proposed by Maldacena in 1997 [2]. A careful analysis of brane em- beddings in SuperString/M Theory led him to conjecture a correspondence between quantum field theories with conformal symmetry (CFT) in D space- time dimensions and Superstring/M theory compactifications on a D + 1 Anti- de-Sitter (AdS) spacetime.
    [Show full text]
  • VECTOR MESON DOMINANCE ∗ Dieter Schildknecht
    Vol. 37 (2006) ACTA PHYSICA POLONICA B No 3 VECTOR MESON DOMINANCE ∗ Dieter Schildknecht Fakultät für Physik, Universität Bielefeld Universitätsstrasse 25, 33615 Bielefeld, Germany [email protected] (Received December 7, 2005) Historically vector meson physics arose along two different paths to be reviewed in Sections 1 and 2. In Section 3, the phenomenological conse- quences will be discussed with an emphasis on those aspects of the subject matter relevant in present-day discussions on deep inelastic scattering in the diffraction region of low values of the Bjorken variable. PACS numbers: 14.40.Cs 1. The gauge principle applied to properties of hadrons In the 1960ies, among particle theorists, there reigned the fairly wide- spread opinion that the theory of strongly interacting particles was to be for- mulated in terms of the unitarity and analyticity properties of the S-matrix by themselves, rather than relying on local quantum field theory. All hadronic states being considered as equally elementary and at the same footing, their dynamics was conjectured to be determined by the “bootstrap conditions” intensively put forward by Chew [1]. In his 1960 paper entitled “Theory of strong interactions”, published in Annals of Physics [2], J.J. Sakurai advocated an entirely different point of view. Starting from the success of the principles of quantum field theory in quantum electrodynamics (QED), he emphasized that one should expect these general principles to also hold for the physics of strong interactions. In particular, the notion of conserved currents, the gauge principle and the uni- versality of couplings should be applied to strong-interaction physics.
    [Show full text]
  • From Nuclear Matter to Neutron Stars
    The University of Adelaide Thesis submitted for the degree of Doctor of Philosophy in Theoretical Physics Department of physics and Special research centre for the subatomic structure of matter Hadrons and Quarks in Dense Matter: From Nuclear Matter to Neutron Stars Supervisors: Author: Prof. A. W. Thomas Daniel L. Whittenbury Prof. A. G. Williams Dr R. Young November 10, 2015 Contents List of Tables vii List of Figures ix Signed Statement xv Acknowledgements xvii Dedication xix Abstract xxi List of Publications xxiii 1 Introduction 1 2 From Nuclear Physics to QCD and Back Again 9 2.1 NN Interaction and Early Nuclear Physics . .9 2.2 Basic Notions of Quantum Chromodynamics . 16 2.2.1 QCD Lagrangian and its Symmetries . 17 2.2.2 Asymptotic Freedom and Perturbation Theory . 21 2.2.3 Chiral Effective Field Theory . 24 2.3 Nuclear Matter . 25 2.4 Experimental and Theoretical Knowledge of the Nuclear EoS . 30 2.5 Quantum Hadrodynamics and the Relativistic Mean Field Approximation 35 2.6 The Quark-Meson Coupling Model . 42 3 General Relativity and the Astrophysics of Neutron Stars 47 3.1 Hydrostatic Equilibrium . 49 3.2 The Neutron Star EoS . 51 4 Hartree-Fock QMC Applied to Nuclear Matter 57 4.1 The Hartree-Fock QMC . 58 4.2 The Lagrangian Density . 59 4.3 Equations of Motion and the MFA . 61 4.4 The Hamiltonian Density . 62 4.5 Hartree-Fock Approximation . 64 4.6 The In-medium Dirac Equation . 72 iii 4.7 Detailed Evaluation of σ Meson Fock Term . 73 4.8 Final Expressions for the Fock Terms .
    [Show full text]
  • Vector Meson Production and the Dipole Picture in Photon-Hadron Scattering
    The Pennsylvania State University The Graduate School Eberly College of Science VECTOR MESON PRODUCTION AND THE DIPOLE PICTURE IN PHOTON-HADRON SCATTERING A Thesis in Physics by Ted C. Rogers c 2006 Ted C. Rogers Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy August 2006 The thesis of Ted C. Rogers was reviewed and approved∗ by the following: Mark Strikman Professor of Physics Thesis Adviser Chair of Committee John Collins Distinguished Professor of Physics Richard W. Robinett Professor of Physics Yuri Zarhin Professor of Mathematics Jayanth Banavar Professor of Physics Head of the Department of Physics ∗Signatures are on file in the Graduate School. iii Abstract This thesis extends and combines traditional methods of hadronic physics, quantum chromodynamics, and nuclear physics so that they may be consistently applied to particular new and interesting regimes of photon(lepton)-hadron scattering. High energy photo(lepto)- production from the deuteron offers a unique opportunity to experimentally test qualitative aspects of the Strong interaction, and to investigate the possibility of applying perturbative quantum chromodynamics (QCD) methods to nuclear physics. New experiments planned at Jefferson National Laboratory and Brookhaven National Laboratory may soon make this possible. Furthermore, there has been a steady increase in the amount of theoretical work being done in nonperturbative QCD, and in extending perturbative QCD methods to new kinematical regimes. As such, it is becoming increasingly important to understand the interplay of perturbative and nonperturbative effects in hadronic interactions, and to establish the boundary of the kinematic regions where traditional pQCD methods can be applied.
    [Show full text]
  • Theoretical Studies of Hadronic Reactions with Vector Mesons
    Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1361 Theoretical Studies of Hadronic Reactions with Vector Mesons CARLA TERSCHLÜSEN ACTA UNIVERSITATIS UPSALIENSIS ISSN 1651-6214 ISBN 978-91-554-9532-9 UPPSALA urn:nbn:se:uu:diva-281288 2016 Dissertation presented at Uppsala University to be publicly examined in Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, Thursday, 19 May 2016 at 10:15 for the degree of Doctor of Philosophy. The examination will be conducted in English. Faculty examiner: Prof. Dr. Stefan Scherer (Mainz University). Abstract Terschlüsen, C. 2016. Theoretical Studies of Hadronic Reactions with Vector Mesons. Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1361. 63 pp. Uppsala: Acta Universitatis Upsaliensis. ISBN 978-91-554-9532-9. Aiming at a systematic inclusion of pseudoscalar and vector mesons as active degrees of freedom in an effective Lagrangian, studies have been performed in this thesis concerning the foundations of such an effective Lagrangian as well as tree-level and beyond-tree-level calculations. Hereby, vector mesons are described by antisymmetric tensor fields. First, an existing power counting scheme for both pseudoscalar and vector mesons is extended to include the pseudoscalar-meson singlet in a systematic way. Based on this, tree- level calculations are carried out which are in good agreement with the available experimental data and several processes are predicted. In particular, the ω-π0 transition form factor is in better agreement with experimental data than the prediction done in the vector-meson- dominance model. Furthermore, a Lagrangian with vector mesons is used together with the leading contributions of chiral perturbation theory in order to calculate tree-level reactions in the sector of odd intrinsic parity.
    [Show full text]
  • Vector-Meson Interactions, Dynamically Generated Molecules, and the Hadron Spectrum
    Vector-meson interactions, dynamically generated molecules, and the hadron spectrum Dissertation zur Erlangung des Doktorgrades (Dr. rer. nat.) der Mathematisch-Naturwissenschaftlichen Fakultät der Rheinischen Friedrich-Wilhelms-Universität Bonn von Dilege Gülmez aus Ankara, Turkey Bonn, 21.06.2018 Dieser Forschungsbericht wurde als Dissertation von der Mathematisch-Naturwissenschaftlichen Fakultät der Universität Bonn angenommen und ist auf dem Hochschulschriftenserver der ULB Bonn http://hss.ulb.uni-bonn.de/diss_online elektronisch publiziert. 1. Gutachter: Prof. Dr. Ulf-G. Meißner 2. Gutachterin: Prof. Dr. Cristoph Hanhart Tag der Promotion: 27.07.2018 Erscheinungsjahr: 2018 Abstract We study the lowest-lying vector-meson interactions and dynamically generated bound states. Therefore, these bound states are studied as hadronic molecules. We demonstrate that some unitarization methods are not well-defined to study the pole structures of amplitudes in the region far from the threshold. We employ an improved unitarization method based on a covariant formalization that is necessary to study the pole structures of amplitudes in the region far from the threshold. In this work, first, we study the analysis of the covariant ρρ scattering in a unitarized chiral theory and then extend it to the strange sector, i.e. SU(3) chiral symmetry. We demonstrate that the on-shell factorization of the Bethe-Salpeter equation is not suitable away from the threshold. Moreover, the left-hand cuts would overlap the right-hand cuts for the coupled-channel unitarization of the Bethe-Salpeter equation. It makes unitarized amplitudes non-analytical and the poles of amplitudes, associated to possible bound states or resonances, unreliable. To avoid this difficulty, we employ the first iterated solution of the N/D method and investigate the possible dynamically generated resonances and bound states.
    [Show full text]