DOCSLIB.ORG

SOFT QCD LIGHT QUARK PHYSICS with CHROMODYNAMICS Nathan

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
SOFT QCD LIGHT QUARK PHYSICS with CHROMODYNAMICS Nathan 247 SOFT QCD LIGHT QUARK PHYSICS WITH CHROMODYNAMICS Nathan Isgur Department of Physics University of Toronto Toronto, Canada MSS 1A7 The addition of dynamical ingredients suggested by QCD dramatically improves the ability of quark models to describe soft hadronic phenomena . This approach is discussed in terms of a particularly simple non-relativistic potential model which has been used to study the spectroscopy, decays, and static properties of baryons and mesons . The application of the model to such QCD exotica as multiquark states and glueballs is also mentioned. In addition, an attempt is made to at least partially rationalise the success of the model in terms of more fundamental physics. 248 I. Introduction to the Model Why Potential Models? A. The successes of quarkonium models for the cc and bb systems , based on a non-relativistic potential model with flavour and spin independent con­ finement and one gluon exchange, at least raise the question of where , as a function of quark mass, such models become useless. �he models I will discuss here are,in response to this question, based on an optimistic extension of the physics expected from QCD for heavy quark sys tems into the light quark domain . We shall see that the models not only provide a useful framework within which to describe the physics of such systems , but moreover that this extension has, at least at some level , been successful. The reasons for this success are only partly understood; a possible beginning for an interpretation is given below. While there are many possible variants, I will concentrate on the l,Z,3) version of such models that I know best It has three main ingredients: confinement , "point-like" constituent quarks, and one gluon exchange . B. How Do Potentials Confine Colour? It is non-trivial to construct a potential which will, for example, 4) confine qqq but not qq. One solution is to assume---b ased on a colour electric flux tube mechanism for confinement---a colour-dependent two body potential between quarks i and j of the form (1) with V(r ) a flavour and spin independent confining potential and with the ij prescription that antiquark potentials follow by the replacement c * _,_ (--t ) . The resulting model allows only colour singlet hadrons to t t = 1) exist , but has the property that wh ile the confinement of qq and qqq is automatic, the existence of more complicated colour singlet bound states (like qqqq) becomes a dynamical issue . The model is also very economical in that it relates the physics of baryons , mesons , and multiquark systems ; this feature will be discussed below. 249 C. What Are the Constituent Quarks? The quarks of the model are not the current quarks of the QCD Lagrangian, but rather a set of "dressed" constituent quarks appropriate to the distance scale of light hadrons , These quarks (which are assumed to be approximately Pointlike) have masses which are (in part by their nature and in . part because they are at this stage also probably repositories of some of our ignorance about the potential, relativistic corrections, etc.) ill-known, but the values m m 0.33 GeV (2) u d m - m MeV (3) d u 6 m 0.55 GeV (4) s m 1. 75 GeV (5) c etc. , are typical . These masses play a crucial role in the model because their differences are the principal origin of flavour symmetry breaking. Note that if we assume that the quarks in a proton are in a Gaussian wave function with 2 the proton 's observed charge radius , then with these masses � 100 MeV so that these light quark models are probably not hopelessly relativistic . � D. Where Are the Gluons? The last principal ingredient of the model is one gluon exchange . The mo st important effects of this type are due to colour hyperfine (magnetic dipole-magr,etic dipole) interactions which in lowest order in " s are given by ij ll --hyp - s.·s.J } l J (6) where 2a s in baryon 3m m a i j (7) 4a s in a meson 3m m i j The first term of ' called the contact term, is , in electromagnetism, l\iyp responsible for the 21 centimetre line of hydrogen; the second (tensor) term is the usual interaction of a magnetic dipole with a magnetic dipole field. The most important characteristics of H are : 1) it is short range in h y §__ 2) it gives a fixed relation ( �) etween the strengths of the contact 3 S.l ·S.J , and tensor terms , 3) it has a strength inversely proportional to the product � 250 of the quark masses, and it violates SU (6) and in particular automatically 4) gives m m and m p > n � > �· One gluon exchange also gives ris·e to spin-orbit interactions from the interaction of a moving quark colour magnetic moment with colour electric fields . As in the case of electromagnetism, this effect tends to be masked by Thomas precession (the relativistic precession of an accelerated spin) , but in this case the suppression of spin-orbit effects is (in the case of qq with m ) by a factor of (1-l;z- f) where the and the "f" come from Thomas mq >> q "'>" precession in the Coulomb-like and confinement potentials, respectively. In the light quark hadrons , the quark wave function overlaps very strongly with the confinement region so that f is very large and spin-orbit effects are 5) suppressed , Finally, one gluon exchange gives rise to a variety of spin­ independent effects which can normally be absorbed into the unknown confinement potential . Most prominent among these is, of course, the Coulomb-like l/r potential itself . II. Baryons First A. Why Baryons First? We begin our discussion of the model with the qqq baryon sector even though the qq meson sector is simpler to treat theoretically . There are several reasons for doing this; probably the most important of these is that the baryons are much better known experimentally than the corresponding mesons (a consequence of their accessibility as s-channel resonances) . Not only are more resonances known , but their masses and widths are better known and there is a wealth of information on their (signed) decay amplitudes . Specifically, the P-wave mesons remain very poorly known (think of the A and the while 1 E) , all seven expected S=O P-wave baryons are known and have reasonably well measured amplitudes for both electromagnetic and strong channels (typically 5 to 10 amplitudes per resonance). Aside from their being more extensively known, baryons probably have other advantages in practice . For one thing, the quarks in a baryon appear to be somewhat more non-relativistic than those in a meson, making their treatment more reliable. It is also possible that three bodies are sufficient to make the effective potential seen by a quark in a baryon significantly "smoother" than in a meson, thereby making baryons less sensitive to precise knowledge of the potentials. Finally, baryons do not have the isoscalar mixing problem (to be described below) which , while interesting, renders I=O meson data unreliable for spectroscopic studies and leaves very few 251 mesons indeed to compare with a potential mo del. B. What is the Model for Baryons and Its Solution? The application of the model to baryons is quite straightforward in 6 7) 8 9 10) . its simplest form ' . Building on the pre-QCD analyses ' ' (which were on their own terms already very successful) we take the simple Hamiltonian p ,2 H 3 = E ( m E i 2 . (8) i=l + i > + i<J and solve it approximately by �setting and treating � and the anharmonicity U as perturbations . Note that V here yp contains both the "true" confinement potential and pieces of the one gluon exchange potential (so that U may contain l/r terms , linear terms , etc.) ; also note that spin orbit effects have been completely dropped . We have already mentioned that Thomas precession is expected to make spin-orbit effects smaller, but the adequacy of completely neglecting them in baryons is not well understood. Evidence from me sons , where the suppression is more easily studied, 5) does , however, tend to support this approach . The approximate solution of this model Hamiltonian is simple. In the harmonic limit with m = m m and m m' (the most general case required for 1 2 = = 3 u, d, and s quarks in the approximation m = m ), u d p 2 p 2 p A 2 2 H +--+ -- + - k ( p + A (10) 2m 2m;i. 23 ) p where _,. _,. _,. p = l r - r (11) /2 ( l 2 _,. 1 _,. _,. _,. A r r 2r (12) = /6 ( l + 2 3 and mp m (13) m (14) A 2m+m'3mm1 so that the unperturbed spectra with up to two units of excitation are those of Figure I. One interesting -- and important -- feature is that the solutions of 6) the confinement problem maximally violate SU(6) in excited baryons . For + example, the p-A basis = 2 eig�nfunction p! is a 45° mixture of the LP . 12 2 + 1 2 2 [56,2+ ) wave function (p + A ) and the [70,2 ) wave function /2 + + rz (p A ) + + 252 (r S=n,-J I: Jigure the unperturbed solutions to the harmonic confinement problem (with arbitrary scales set to give the same spacing in each sector) . of SU(6) . Clearly, to the extent that this phenomenon is important , an SU(6) (or even SU (3)) analysis of excited baryons will fail. We next take these states and perturb them with the anharmonic term U.
Load more

Recommended publications
  • An Introduction to the Quark Model Arxiv:1205.4326V2 [Hep-Ph]
    An introduction to the quark model Jean-Marc Richard Université de Lyon & Institut de Physique Nucléaire de Lyon IN2P3-CNRS & UCB, 4 rue Enrico Fermi, 69622 Villeurbanne, France [email protected] May 25, 2012 Abstract This document contains a review on the quark model, prepared for lectures at the Niccolò Cabeo School at Ferrara in May 2012. It includes some historical aspects, the spectral properties of the 2-body and 3-body Schrödinger operators applied to mesons and baryons, the link between meson and baryon spectra, the role of flavour independence, and the speculations about stable or metastable multiquarks. The analogies between few-charge systems and few-quark bound states will be under- lined. Contents 1 Prelude: few charge systems in atomic physics 3 1.1 Introduction . .3 1.2 The atomic two-body problem . .3 1.3 Three-unit-charge ions . .5 arXiv:1205.4326v2 [hep-ph] 24 May 2012 1.4 Three-body exotic ions . .5 1.5 Molecules with four unit charges . .6 2 A brief historical survey 7 2.1 Prehistory . .7 2.2 Early hadrons . .7 2.3 Generalised isospin . .9 2.4 The success of the eightfold way . 10 2.5 The fundamental representation: quarks . 10 2.6 The OZI rule . 12 2.7 First quark models . 13 2.8 Heavy quarks . 14 2.9 Confirmation . 15 1 2 AN INTRODUCTION TO THE QUARK MODEL 3 The quark–antiquark model of mesons 16 3.1 Introduction . 16 3.2 Quantum numbers . 16 3.3 Spin averaged spectrum . 17 3.4 Improvements to the potential .
    [Show full text]
  • At the Lhcb Experiment
    Summer student project report: Search for the decay ∗ ± ∗± 퐷푠(2317) → 퐷푠 훾 at the LHCb experiment Lukas Calefice1,2,* and Supervisor: Ricardo Vázquez Gómez2,** 1Fakultät Physik, Technische Universität Dortmund, 2LHCb collaboration, CERN, *[email protected], **[email protected] September 2018 Abstract ∗ ± ∗± The summer student project treated the search for the radiative decay 퐷푠(2317) → 퐷푠 훾 with the 2016 and 2017 data sets collected by the LHCb experiment corresponding to 3.3 fb−1 at a centre- ∗ ± ∗± ∗ ± of-mass energy of 13 TeV. For the search the ratio BR(퐷푠(2317) → 퐷푠 훾)/BR(퐷푠(2317) → ± 0 ∗ ± ∗± 퐷푠 휋 ) was investigated, but no hint for the existence of 퐷푠(2317) → 퐷푠 훾 was found. 1 Introduction The spectroscopy of heavy-light mesons can mostly be described successfully with non-relativistic quark potential models in the limit of Heavy Quark Effective Theory (HQET), in which the mesons can be considered as a hydrogen atom. The limit requires that 푚Q → ∞, which is the mass of the ⃗ meson’s heavy quark. In that case the spin of the heavy quark 푆Q is decoupled from the orbital angular momentum 푙 ⃗ between the quarks and states in the spectrum are identified by the quantum numbers 푗 푗 = 퐿 + 푠q, 퐿 and 퐽. Therefore the 푃-wave (퐿 = 1) states are expected to be doubly degenerated in the spin of the heavy quark. Moreover new symmetries called Heavy Flavour Symmetry and Heavy Spin Symmetry come along with the HQET that make it possible to estimate several mass states and branching fractions.
    [Show full text]
  • March/April 2001NEWSLETTER
    March/April 2001 THOMAS JEFFERSON NATIONAL ACCELERATOR FACILITY • A DEPARTMENT OF ENERGY FACILITY Nathan Isgur comments on being awarded the Sakurai Sakurai winner! Prize Nathan Isgur receives American Physical Society award for 2001 Introducing Warren Funk, athan Isgur, Jefferson Lab’s Senior heavier quarks have been difficult to JLab’s SNS Project Services Manager NTheorist and Chief Scientist, was determine experimentally because it is one of three physicists recognized in dramatically harder to create and study March by the American Physical pairs of them than is the case for pairs of Society as this year’s recipients of the lighter quarks. J.J. Sakurai Prize for Theoretical Scientists like to examine objects indi- Introducing Rusty Sprouse, Particle Physics. vidually but this is impossible with quarks Lab’s Plant Engineering Director The prize is shared by the team of in nature because they are always bound Isgur and Mark Wise of Caltech, and to other quarks in pairs or groups of independently by Mikhail Voloshin of threes. The six different quarks that have the University of Minnesota. been identified in nature (in order of Gwyn Williams named APS These three developed a theory that increasing mass) are: up, down, strange, Fellow; Anne Reilly takes National allows physicists to deduce the indi- charm, bottom and top. The heaviest Science Foundation award vidual quark behavior of the very quark (the top) is about 100,000 times the heavy bottom quark by showing how mass of the lightest quark (the up). Deriving its properties can be directly inferred useful conclusions about quarks can now from the measurements of the charm be better addressed due to the discovery Countdown to JLab quarks.
    [Show full text]
  • Workshops and Awards 6.2009
    AWARDS Alessandro Bacchetta, Nathan Isgur Distinguished Fellowship, 2008-2009 Anatoly Radyushkin, 2008 Distinguished Research Award, Old Dominion University Student Award: Ian Cloet, shared 2008 SURA Thesis Prize Student Award: Giovanni Chirilli, JSA/Jefferson Laboratory Graduate Fellowship, 2008-2009 U.S. Patent No. 7,444,009 B1 issued October 28, 2008: Method to Improve Cancerous Lesion Detection Sensitivity in a Dedicated Dual-Head Scintimammography System by Douglas A. Kieper, Stanislaw Majewski, Benjamin L. Welch Student Award: Yoni Kahn, second prize, National DOE Undergraduate Poster Contest, Oak Ridge, Nov. 2008 Science Champion Discovery Award (Discovery Center, Halifax) – Adam Sarty – November, 2008 APS Fellow Jian-Ping Chen, Physics Division. Citation from Hadronic Physics: For contributions to understanding the spin structure of the neutron, through the use of a polarized Helium-3 target. December, 2008 APS Fellow Peter Kneisel, Accelerator Division. Citation from Physics of Beams: For pioneering contributions to superconducting rf science and technology through a wide range of research and development advances. December, 2008 DOE Office of Science Best in Class Environmental Sustainability Award for fiscal Year 2008 for two projects spearheaded by JLab staff: Circuit Board Saves Cable and Refurbished Sodium Iodide Crystals Serve New Use, December 2008 U.S. Patent No. 7,471,052 B2 issued December 30, 2008: Cryogenic Vacuum RF Feedthrough Device invented by Genfa Wu and Harry Lawrence Phillips Department of Energy Office of Science Best in Class Environmental Sustainability Award –Jian Jian- Ping Chen – December, 2008 DOE Science Best in Class Environmental Sustainability Award – Alexandre Camsonne – December, 2008 APS Fellow Gerassimos Petratos, Kent State University and JLab Physics User.
    [Show full text]
  • Interpreting the Neutron's Electric Form Factor: Rest Frame Charge
    JLAB-THY-98-48 Interpreting the Neutron’s Electric Form Factor: Rest Frame Charge Distribution or Foldy Term? Nathan Isgur Jefferson Lab 12000 Jefferson Avenue, Newport News, Virginia, 23606 Abstract The neutron’s electric form factor contains vital information on nucleon structure, but its interpretation within many models has been obscured by relativistic effects. I demonstrate that, to leading order in the relativistic ex- arXiv:hep-ph/9812243v1 3 Dec 1998 pansion of a constituent quark model, the Foldy term cancels exactly against a contribution to the Dirac form factor F1 to leave intact the naive inter- n pretation of GE as arising from the neutron’s rest frame charge distribution. 1 I. INTRODUCTION In 1962, Sachs showed [1] that the combinations of elastic nucleon form factors (N = p or n) 2 N N Q N GE = F1 − 2 F2 (1) 4mN N N N GM = F1 + F2 (2) have simple interpretations as the spatial Fourier transforms of the nucleons’ charge and Q~ magnetization distributions in the Breit frame (where momentum ~p = − 2 is scattered to ′ Q~ N N momentum ~p =+ 2 ). Here F1 and F2 are the Dirac and Pauli form factors, respectively, defined by µν ′ ′ µ ′ ′ N µ σ qν N hN(~p ,s )|jem(0)|N(~p, s)i =u ¯(~p ,s )[F1 γ + i F2 ]u(~p, s) (3) 2mN ′ N N 2 2 where qν = pν − pν and F1 and F2 are functions of Q = −q . These form factors obviously contain vital information on the internal composition of the nucleons. Although it has proven elusive experimentally, the electric form factor of the n n neutron GE is particularly fascinating in this respect.
    [Show full text]
  • General Kofi A. Annan the United Nations United Nations Plaza
    MASSACHUSETTS INSTITUTE OF TECHNOLOGY DEPARTMENT OF PHYSICS CAMBRIDGE, MASSACHUSETTS O2 1 39 October 10, 1997 HENRY W. KENDALL ROOM 2.4-51 4 (617) 253-7584 JULIUS A. STRATTON PROFESSOR OF PHYSICS Secretary- General Kofi A. Annan The United Nations United Nations Plaza . ..\ U New York City NY Dear Mr. Secretary-General: I have received your letter of October 1 , which you sent to me and my fellow Nobel laureates, inquiring whetHeTrwould, from time to time, provide advice and ideas so as to aid your organization in becoming more effective and responsive in its global tasks. I am grateful to be asked to support you and the United Nations for the contributions you can make to resolving the problems that now face the world are great ones. I would be pleased to help in whatever ways that I can. ~~ I have been involved in many of the issues that you deal with for many years, both as Chairman of the Union of Concerne., Scientists and, more recently, as an advisor to the World Bank. On several occasions I have participated in or initiated activities that brought together numbers of Nobel laureates to lend their voices in support of important international changes. -* . I include several examples of such activities: copies of documents, stemming from the . r work, that set out our views. I initiated the World Bank and the Union of Concerned Scientists' examples but responded to President Clinton's Round Table initiative. Again, my appreciation for your request;' I look forward to opportunities to contribute usefully. Sincerely yours ; Henry; W.
    [Show full text]
  • Jefferson Lab's 12 Gev Upgrade Achieves Critical Decision-Zero
    Spring 2004 THOMAS JEFFERSON NATIONAL ACCELERATOR FACILITY • A DEPARTMENT OF ENERGY FACILITY 12 GeV on the horizon Department of Energy approves ‘mission need’ for upgrading CEBAF eputy Secretary of Energy Kyle CEBAF electron beam from its current DMcSlarrow traveled to Jefferson level near 6 GeV to 12 GeV (billion Lab April 19 to announce that the electron volts), build a fourth experi- Department of Energy had established mental hall, and upgrade detector capa- a “mission need” for upgrading the bilities in the three existing experimen- Lab’s Continuous Electron Beam tal halls. Accelerator Facility (CEBAF) and its “Approval of CD-0 for the CEBAF experimental capabilities. During an Upgrade is an important and critical All Staff Meeting that morning, step in building Jefferson Lab’s future,” McSlarrow told Lab employees, visit- said Lab Director Christoph Leemann. Anthony (Tony) W. Thomas ing officials and members of the news “With the 12 GeV Upgrade, Jefferson JLab Chief Scientist and media that DOE had approved the Lab will be firmly anchored as a world Theory Group Head Critical Decision Zero — or CD-0 — leader in the field of hadronic physics document for the proposed CEBAF for many years to come.” 12 GeV Upgrade. Anthony Thomas is “Today marks a special day for all The proposed Upgrade at Jefferson of those within the Lab, among our sci- JLab’s new Chief Lab would double the energy of the entists, at our universities and in our Scientist, Theory head Continued on page 4 nthony (Tony) W. Thomas has Aassumed the mantle of Jefferson Lab Chief Scientist, bringing his 30+ years of experience in nuclear and par- ticle physics to the Lab.
    [Show full text]
  • Exotic Meson Decay Widths Using Lattice Quantum Chromodynamics Merritt .S Cook Florida International University
    Florida International University FIU Digital Commons FIU Electronic Theses and Dissertations University Graduate School 3-16-2006 Exotic meson decay widths using lattice quantum chromodynamics Merritt .S Cook Florida International University DOI: 10.25148/etd.FI14061502 Follow this and additional works at: https://digitalcommons.fiu.edu/etd Part of the Physics Commons Recommended Citation Cook, Merritt .,S "Exotic meson decay widths using lattice quantum chromodynamics" (2006). FIU Electronic Theses and Dissertations. 2526. https://digitalcommons.fiu.edu/etd/2526 This work is brought to you for free and open access by the University Graduate School at FIU Digital Commons. It has been accepted for inclusion in FIU Electronic Theses and Dissertations by an authorized administrator of FIU Digital Commons. For more information, please contact [email protected]. FLORIDA INTERNATIONAL UNIVERSITY Miami, Florida EXOTIC MESON DECAY WIDTHS USING LATTICE QUANTUM CHROMODYNAMICS A dissertation submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in PHYSICS by M erritt S. Cook 2006 To: Interim Dean Mark Szuchman College of Arts and Sciences This dissertation, written by Merritt S. Cook, and entitled Exotic Meson Decay Widths using Lattice Quantum Chromodynamics, having been approved in respect to style and intellectual content, is referred to you for judgment. We have read this dissertation and recommend that it be approved. Rajamani Narayanan Misak Sargsian Brian Raue John T. Landrum H. Rudolf Fiebig, Major Professor Date of Defense: March 16, 2006 The dissertation of Merritt S. Cook is approved. Interim Dean Mark Szuchman College of Arts and Sciences Interim Dean Stephan L. Mintz University Graduate School Florida International University, 2006 © Copyright 2006 by M erritt S.
    [Show full text]
  • Liiiift®T.T DEVELOPMENT REPORT UTPT-85-37
    ' tt-) -.).(J_() CALT-68-1311 DOE RESEARCH AND ;liiiift®t.t DEVELOPMENT REPORT UTPT-85-37 Quark Model Predictions for the Electron Energy Spectrum in Semileptonic D and B Decays* Benjamin Grinsteinf 1 and Mark B. Wise! 2 California Institute of Technology, Pasadena, CA 91125 Nathan Isgur Department of Physics, University of Toronto, Toronto, Canada M5S 1A7 ABSTRACT The constituent quark model is used to predict the electron energy spectrum in semileptonic D and B meson decays. Particu- Jar attention is paid to the endpoint region of the electron spec- trum in B decays since this is crucial to a determination of the b --> u weak mixing angle. January?, 1986 f lT~~-;~R~~arch Fellow f 2 Alfred P. Sloan Foundation Fellow and U.S. Department of Energy Outstanding Junior Investigator Program under Contract No. DE-FG03-84ER40172. I. Introduction In the standard model, based on the gauge group SU(3) x SU(2) x U(1), the quarks couple to the W -bosons through the weak current (1) In eq. (1) i,j E l!. · · ·, nj are generation indices and Vij is ann x n unitary matrix that arises from diagonalization of the quark mass matrices. At present there is experimental evidence for three generations of quarks and leptons. In this case it is possible, by redefining the phases of quark fields, to write V in terms of three angles 8 1, 8 2 , 83 and a phase o (ref. 1) (2) Here ci = cos8i, si = sin8i and the angles 8i are chosen to lie in the first qua- drant.
    [Show full text]
  • Arxiv:1606.08593V3 [Hep-Ph] 3 Oct 2016
    Exotic hadrons: review and perspectives 1, J.-M. Richard ∗ 1Université de Lyon, Institut de Physique Nucléaire de Lyon, IN2P3-CNRS–UCBL, 4 rue Enrico Fermi, 69622 Villeurbanne, France (Dated: Version of October 4, 2016) The physics of exotic hadrons is revisited and reviewed, with emphasis on flavour configurations which have not yet been investigated. The constituent quark model of multiquark states is discussed in some detail, as it can serve as a guide for more elaborate approaches. I. INTRODUCTION the regularity patterns of the rest of the spectrum. The ex- otic character of a hadron is of course a time-dependent The physics of hadrons began about one century ago, concept: once a striking property of a hadron is con- when it became appealing to build nuclei from protons firmed by further measurements, and understood within and neutrons. The experimental search for the neutron a plausible theoretical framework, the hadron ceases to was soon resumed along with the search for the particle be exotic. predicted by Yukawa as being responsible for the tight Among the most famous examples, there is the φ me- binding of protons and neutrons. See, e.g., [1] for the son, a peak of mass 1.02 GeV with a remarkably small history of this early period. width of about 4 MeV [6], decaying preferentially into When interacting with nucleons or among themselves, a pair of kaons, though the decay into pions is energeti- the pions produce many resonances. The exchange of me- cally much easier. The decay patterns of the φ are now son resonances, and the formation of nucleon resonances understood from its quark content s¯s, where s denotes in the intermediate states are crucial for our understand- the strange quark, with very little mixing.
    [Show full text]
  • Partial Wave Analysis
    EPJ Web of Conferences 134, 02002 (2017) DOI: 10.1051/ epjconf/201713402002 Subnuclear Structure of Matter: Achievements and Challenges Partial wave analysis Eberhard Klempt1,, Andrey V. Sarantsev1,2,, and Ulrike Thoma1, 1Helmholtz–Institut für Strahlen– und Kernphysik, Universität Bonn, 53115 Bonn, Germany 2National Research Centre "Kurchatov Institute", Petersburg Nuclear Physics Institute, Gatchina, Russia Abstract. The project A.2 of the SFB/TR16 “Subnuclear Structure of Matter” aimed at a combined multichan- nel partial wave analysis of all or of most data on pion and photo-induced reactions for invariant masses from the Δ(1232) region to 2300 MeV. In this review the most important results are presented. It is shown that the data and their partial wave analysis have improved our understanding of the dynamics of excited light-quark baryons significantly. 1 Introduction Arndt and his collaborators [15] found only 8 N∗ and 10 Δ∗-states. This latter analysis included high precision data “Why baryons?” asked Nathan Isgur [1] at NSTAR2000, from the meson factories at LAMPF, PSI, and TRIUMF. ff and gave three answers: Because nucleons are the stu A strong argument in favor of the Arndt et al. analysis was of which our world is made, because they are the sim- the correct prediction of spin rotation parameters [16–18] plest system in which the non-abelian character of QCD and of the backward asymmetry [19] in the elastic pion- is manifest, and because their complexity - compared to proton scattering from ITEP/PNPI; the predictions from mesons - may reveal physics hidden from us in mesons. [11, 12] show clear discrepancies with the data.
    [Show full text]
  • List of Participants -
    47~ - - - APPENDIX IV. - LIST OF PARTICIPANTS - - - - - - - - - - - - - - - - - - - , 473 - ANTIMATTER PHYSICS AT lOW ENERGY WORKSHOP FERMI NATIONAL ACCELERATOR lABORATORY APRIL 10-12, 1986 MARY ALBERG MARINA ARTUSO - PHYSICS DEPARTMENT YoCOLUMBIA GROUP SEATTLE UNIVERSITY CORNELL UNIVERSITY - SEATTLE, WASHINGTON 98122 ITHACA, NEW YORK 14853 DR. PETER D. BARNES DR. BERND BASSALlECK PHYSICS DEPARTMENT DEPT. OF PHYSICS AND ASTRONOMY CARNEGIE-MEllON INSTITUTE UNIVERSITY OF NEW MEXICO PITTSBURGH, PENNSYLVANIA 15213 ALBUQUERQUE, NEW MEXICO 87131 DR. VINOD R. BHARADWAJ MORRIS E. BINKLEY MS 1341 MS 1223 FERMILAB FERMI LAB - P. O. BOX 500 P.O. BOX 500 BATAVIA, IllINOIS 60510 BATAVIA, ILLINOIS 60510 - DR. JAMES D. BJORKEN GARY S. BLANPIED MS 1105 DEPARTMENT OF PHYSICS FERMILAB UNIVERSITY OF SOUTH CAROLINA P.O. BOX 500 COLUMBIA, SOUTH CAROLINA 29208 BATAVIA, ILLINOIS 60510 DR. lEROY N. BLUMBERG DR. BILLY E. BONNER - HIGH ENERGY PHYSICS DIVISION,GTN T. W. BONNER NUCLEAR LABORATORY OFFICE OF ENERGY RESEARCH, ER-224 RICE UNIVERSITY U.S. DEPARTMENT OF ENERGY, GTN P.O. BOX 1892 WASHINGTON, DC 20545 HOUSTON, TEXAS 77251 STANLEY K. BOROWSKI DR. STANLEY J. BRODSKY BUILDING 2001-D.9990 BIN 81 AEROJET TECHSYSTEMS COMPANY STANFORD LINEAR ACCEl. CENTER P.O. BOX 13222 P.O. BOX 4349 SACRAMENTO, CALIFORNIA 95813 STANFORD, CALIFORNIA 94305 RONALD E. BROWN WARREN W. BUCK P-3, MS D449 DEPARTMENT OF PHYSICS LOS ALAMOS NATIONAL LABORATORY HAMPTON UNIVERSITY LOS ALAMOS, NEW MEXICO 87545 HAMPTON, VIRGINIA 23668 PETER CAMERON THOMAS A. CAREY P.O. BOX 404 P-2, MS D456 UPTON, NEW YORK 11973 LOS ALAMOS NATIONAL LABORATORY LOS ALAMOS, NEW MEXICO 87545 DR. NEAL M. CASON DR. MICHAEL S.
    [Show full text]