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Class 5 - the Quark Model

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Class 5 - the Quark Model Class 5 - The Quark Model • Quarks • Mesons - Quark/Antiquark Combinations • Baryons - Three Quark Combinations • Antiparticles • Spin Considerations • Color • Experimental Evidence for Quarks 1 Birth of the Quark Model • In 1964, Murray Gell-Mann and George Zweig inde- pendently developed a theory that would explain all the hadrons • Model based on 3 constituent particles, all with spin 1 of 2 and baryon number of 1/3 • Gell-Mann named them quarks • Quarks come in three flavors Name Symbol Charge Strangeness up u +2/3 0 down d -1/3 0 strange s -1/3 -1 antiup u -2/3 0 antidown d +1/3 0 antistrange s +1/3 +1 2 Mesons • Mesons are quark/antiquark combinations Combination Charge Strangeness Meson uu 0 0 π0; η0; η00 dd 0 0 π0; η0; η00 ud -1 0 π− ud +1 0 π+ us +1 +1 K+ us -1 -1 K− ds 0 +1 K0 ds 0 -1 K0 ss 0 0 η00 3 Meson Diagram ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ £¡£¡£¡£¡£¡£¡£¡£¡£¡£¡£¨¡¨¡¨¡¨¡¨¡¨¡¨¡¨¡¨¡¨¡¨ ¢¡¢¡¢¡¢¡¢¡¢¡¢¡¢¡¢¡¢¡¢¤¡¤¡¤¡¤¡¤¡¤¡¤¡¤¡¤¡¤¡¤©¡©¡©¡©¡©¡©¡©¡©¡©¡©¡© ¡ ¡ ¡ ¡ ¡ ¡ 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    Unification of Nature’s Geoffrey B. West Fredrick M. Cooper Fundamental Forces Emil Mottola a continuing search Michael P. Mattis it was explicitly recognized at the time that basic research had an im- portant and seminal role to play even in the highly programmatic en- vironment of the Manhattan Project. Not surprisingly this mode of opera- tion evolved into the remarkable and unique admixture of pure, applied, programmatic, and technological re- search that is the hallmark of the present Laboratory structure. No- where in the world today can one find under one roof such diversity of talent dealing with such a broad range of scientific and technological challenges—from questions con- cerning the evolution of the universe and the nature of elementary parti- cles to the structure of new materi- als, the design and control of weapons, the mysteries of the gene, and the nature of AIDS! Many of the original scientists would have, in today’s parlance, identified themselves as nuclear or particle physicists. They explored the most basic laws of physics and continued the search for and under- standing of the “fundamental build- ing blocks of nature’’ and the princi- t is a well-known, and much- grappled with deep questions con- ples that govern their interactions. overworked, adage that the group cerning the consequences of quan- It is therefore fitting that this area of Iof scientists brought to Los tum mechanics, the structure of the science has remained a highly visi- Alamos to work on the Manhattan atom and its nucleus, and the devel- ble and active component of the Project constituted the greatest as- opment of quantum electrodynamics basic research activity at Los Alam- semblage of scientific talent ever (QED, the relativistic quantum field os.
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  • People and Things
    People and things An irresistible photograph: at a StAC Christmas party. Laboratory Director Pief Panofsky was presented with a CERN T-shirt, which he promptly put on. With him in the picture are (left to right) Roger Gear hart playing a seasonal master of ceremonies role, J. J. Murray and Ed Seppi. On people Elected vice-president of the Amer­ ican Physical Society for this year is Robert E. Marshak of Virginia Polytechnic Institute and State Uni­ versity. He succeeds Maurice Goldhaberr who becomes president­ elect. The new APS president is Arthur Schawlow of Stanford. In the same elections, Columbia theorist Malvin Ruder man was elected to serve for four years as councillor-at-large. Gisbert zu Pulitz, Scientific Director of the Darmstadt Heavy Ion Linear Accelerator Laboratory and Profes­ sor of Physics at the University of Heidelberg, has been elected as the new Chairman of the Association of German Research Centres (Ar- beitsgemeinschaft der Grossfor- schungseinrichtungen in der Bun- desrepublik Deutschland), succeed­ ing Herwig Schopper. The Associa­ the American Association for the tion includes the Julich and Karls­ Advancement of Science. ruhe nuclear research centres, LEP optimization DESY, and the Max Planck Institute for Plasma Physics as well as other The detail of the LEP electron-posi­ centres in the technical and biome­ tron storage ring project continues dical fields. to be studied so as to optimize the Moves at Brookhaven machine parameters from the point of view of performance and of cost. Nick Samios, former chairman of This optimization stays within the Brookhaven's Physics Department, description of Phase I of LEP which becomes the Laboratory's Deputy was agreed by the Member States Director for High Energy and Nu­ at the CERN Council meeting in clear Physics.
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  • The Eightfold Way Model, the SU(3)-flavour Model and the Medium-Strong Interaction
    The Eightfold Way model, the SU(3)-flavour model and the medium-strong interaction Syed Afsar Abbas Jafar Sadiq Research Institute AzimGreenHome, NewSirSyed Nagar, Aligarh - 202002, India (e-mail : [email protected]) Abstract Lack of any baryon number in the Eightfold Way model, and its intrin- sic presence in the SU(3)-flavour model, has been a puzzle since the genesis of these models in 1961-1964. In this paper we show that this is linked to the way that the adjoint representation is defined mathematically for a Lie algebra, and how it manifests itself as a physical representation. This forces us to distinguish between the global and the local charges and between the microscopic and the macroscopic models. As a bonus, a consistent under- standing of the hitherto mysterious medium-strong interaction is achieved. We also gain a new perspective on how confinement arises in Quantum Chro- modynamics. Keywords: Lie Groups, Lie Algegra, Jacobi Identity, adjoint represen- tation, Eightfold Way model, SU(3)-flavour model, quark model, symmetry breaking, mass formulae 1 The Eightfold Way model was proposed independently by Gell-Mann and Ne’eman in 1961, but was very quickly transformed into the the SU(3)- flavour model ( as known to us at present ) in 1964 [1]. We revisit these models and look into the origin of the Eightfold Way model and try to un- derstand as to how it is related to the SU(3)-flavour model. This allows us to have a fresh perspective of the mysterious medium-strong interaction [2], which still remains an unresolved problem in the theory of the strong interaction [1,2,3].
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  • Murray Gell-Mann Hadrons, Quarks And
    A Life of Symmetry Dennis Silverman Department of Physics and Astronomy UC Irvine Biographical Background Murray Gell-Mann was born in Manhattan on Sept. 15, 1929, to Jewish parents from the Austro-Hungarian empire. His father taught German to Americans. Gell-Mann was a child prodigy interested in nature and math. He started Yale at 15 and graduated at 18 with a bachelors in Physics. He then went to graduate school at MIT where he received his Ph. D. in physics at 21 in 1951. His thesis advisor was the famous Vicky Weisskopf. His life and work is documented in remarkable detail on videos that he recorded on webofstories, which can be found by just Google searching “webofstories Gell-Mann”. The Young Murray Gell-Mann Gell-Mann’s Academic Career (from Wikipedia) He was a postdoctoral fellow at the Institute for Advanced Study in 1951, and a visiting research professor at the University of Illinois at Urbana– Champaign from 1952 to 1953. He was a visiting associate professor at Columbia University and an associate professor at the University of Chicago in 1954-55, where he worked with Fermi. After Fermi’s death, he moved to the California Institute of Technology, where he taught from 1955 until he retired in 1993. Web of Stories video of Gell-Mann on Fermi and Weisskopf. The Weak Interactions: Feynman and Gell-Mann •Feynman and Gell-Mann proposed in 1957 and 1958 the theory of the weak interactions that acted with a current like that of the photon, minus a similar one that included parity violation.
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  • A Peek Into Spin Physics
    A Peek into Spin Physics Dustin Keller University of Virginia Colloquium at Kent State Physics Outline ● What is Spin Physics ● How Do we Use It ● An Example Physics ● Instrumentation What is Spin Physics The Physics of exploiting spin - Spin in nuclear reactions - Nucleon helicity structure - 3D Structure of nucleons - Fundamental symmetries - Spin probes in beyond SM - Polarized Beams and Targets,... What is Spin Physics What is Spin Physics ● The Physics of exploiting spin : By using Polarized Observables Spin: The intrinsic form of angular momentum carried by elementary particles, composite particles, and atomic nuclei. The Spin quantum number is one of two types of angular momentum in quantum mechanics, the other being orbital angular momentum. What is Spin Physics What Quantum Numbers? What is Spin Physics What Quantum Numbers? Internal or intrinsic quantum properties of particles, which can be used to uniquely characterize What is Spin Physics What Quantum Numbers? Internal or intrinsic quantum properties of particles, which can be used to uniquely characterize These numbers describe values of conserved quantities in the dynamics of a quantum system What is Spin Physics But a particle is not a sphere and spin is solely a quantum-mechanical phenomena What is Spin Physics Stern-Gerlach: If spin had continuous values like the classical picture we would see it What is Spin Physics Stern-Gerlach: Instead we see spin has only two values in the field with opposite directions: or spin-up and spin-down What is Spin Physics W. Pauli (1925)
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  • Lesson 49: Quarks
    Lesson 49: Quarks By 1960 physicists felt pretty much like you do right now... confused! • Leptons are really small, and there are only six of them (and their antiparticles), so it seems like they are probably fundamental particles. • The hadrons (mesons and baryons) are really big, and there are so many of them, that it seems like maybe they are made up of just a few other smaller fundamental particles. ◦ In 1963 Murray Gell-Mann and George Zweig independently suggested the properties of the fundamental particles that make up the hadrons, named quarks. To explain the two most important hadrons, protons and neutrons, we only need two of these quarks... 2 up quark with a e charge → symbol is u. ◦ 3 1 down quark with a − e charge → symbol is d. ◦ 3 • This bothered physicists, since it involved having charges that were a fraction of an elementary charge, which had never been seen. electrons ◦ By 1967 the Stanford Linear Accelerator was u u being used to shoot high energy electrons at protons. The electrons deflected around the d proton in an uneven pattern that suggested the electrons proton charge of a proton was not evenly spread out, just as the quark model suggested. Illustration 1: The electrons are deflected around • The quark model eventually built up to having six the proton because of the concentration of quarks and their antiparticles (wow! just like there positively charged quarks near the top and are six leptons and their antiparticles). negatively charged quarks near the bottom. ◦ With these six quarks and their antiquarks we can explain all the hadrons.
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  • The Eightfold Way John C
    The Eightfold Way John C. Baez, May 27 2003 It is natural to group the eight lightest mesons into 4 irreps of isospin SU(2) as follows: mesons I3 Y Q pions (complexified adjoint rep) π+ +1 0 +1 π0 0 0 0 π− -1 0 -1 kaons (defining rep) K+ +1/2 1 +1 K0 -1/2 1 0 antikaons (dual of defining rep) K0 +1/2 -1 0 K− -1/2 -1 -1 eta (trivial rep) η 0 0 0 (The dual of the defining rep of SU(2) is isomorphic to the defining rep, but it's always nice to think of antiparticles as living in the dual of the rep that the corresponding particles live in, so above I have said that the antikaons live in the dual of the defining rep.) In his theory called the Eightfold Way, Gell-Mann showed that these eight mesons could be thought of as a basis for the the complexified adjoint rep of SU(3) | that is, its rep on the 8- dimensional complex Hilbert space su(3) C = sl(3; C): ⊗ ∼ He took seriously the fact that 3 3 sl(3; C) C[3] = C (C )∗ ⊂ ∼ ⊗ 3 3 where C is the defining rep of SU(3) and (C )∗ is its dual. Thus, he postulated particles called quarks forming the standard basis of C3: 1 0 0 u = 0 0 1 ; d = 0 1 1 ; s = 0 0 1 ; @ 0 A @ 0 A @ 1 A 3 and antiquarks forming the dual basis of (C )∗: u = 1 0 0 ; d = 0 1 0 ; s = 0 0 1 : This let him think of the eight mesons as being built from quarks and antiquarks.
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  • Sakata Model Precursor 2: Eightfold Way, Discovery of Ω- Quark Model: First Three Quarks A
    Introduction to Elementary Particle Physics. Note 20 Page 1 of 17 THREE QUARKS: u, d, s Precursor 1: Sakata Model Precursor 2: Eightfold Way, Discovery of ΩΩΩ- Quark Model: first three quarks and three colors Search for free quarks Static evidence for quarks: baryon magnetic moments Early dynamic evidence: - πππN and pN cross sections - R= σσσee →→→ hadrons / σσσee →→→ µµµµµµ - Deep Inelastic Scattering (DIS) and partons - Jets Introduction to Elementary Particle Physics. Note 20 Page 2 of 17 Sakata Model 1956 Sakata extended the Fermi-Yang idea of treating pions as nucleon-antinucleon bound states, e.g. π+ = (p n) All mesons, baryons and their resonances are made of p, n, Λ and their antiparticles: Mesons (B=0): Note that there are three diagonal states, pp, nn, ΛΛ. p n Λ Therefore, there should be 3 independent states, three neutral mesons: π0 = ( pp - nn ) / √2 with isospin I=1 - - p ? π K X0 = ( pp + nn ) / √2 with isospin I=0 0 ΛΛ n π+ ? K0 Y = with isospin I=0 Or the last two can be mixed again… + 0 Λ K K ? (Actually, later discovered η and η' resonances could be interpreted as such mixtures.) Baryons (B=1): S=-1 Σ+ = ( Λ p n) Σ0 = ( Λ n n) mixed with ( Λ p p) what is the orthogonal mixture? Σ- = ( Λ n p) S=-2 Ξ- = ( Λ Λp) Ξ- = ( Λ Λn) S=-3 NOT possible Resonances (B=1): ∆++ = (p p n) ∆+ = (p n n) mixed with (p p p) what is the orthogonal mixture? ∆0 = (n n n) mixed with (n p p) what is the orthogonal mixture? ∆- = (n n p) Sakata Model was the first attempt to come up with some plausible internal structure that would allow systemizing the emerging zoo of hadrons.
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  • The Extraction of the ¯ D/¯U Ratio in Nuclear Media
    The Extraction of the d=¯ u¯ Ratio in Nuclear Media by Marshall Scott A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Applied Physics) in The University of Michigan 2020 Doctoral Committee: Professor Wolfgang Lorenzon, Chair Professor Christine Aidala Professor Jianming Qian Professor Gregory Tarle Marshall Scott [email protected] ORCID iD:0000-0003-1105-1033 c Marshall Scott 2020 Acknowledgments First and foremost I would like to thank my parents, Billy Scott and Alyce Coffey, and my brother Langston Scott for always being there for me and supporting me throughout my life. Words cannot describe how fortunate I am to have these three pillars in my life. I would also like to acknowledge my extended family. A heartfelt thank you goes out to Tristan Geis and Thu Huynh for your love, kindness, and for being my home away from home for all of these years. I would also like to thank Rachel Moss, Liz Lindly, Daniel and Laurelyn Leimer, Kathleen Stafford, Alan McCray, and Micheal and Lauren Baird for your deep, loving friendship. I don’t know where I would be without Erika Ellis, Amee´ ”A. J. Maloy” Hennig, Jazmin Berlanga Medina, and Amy Ireton. Your insight, thoughtfulness, and support has often been the light at the end of a very dark tunnel. I would also like to thank Jerry and Leete Kendrick for always making me feel like family and Anastasia Rumsey and Leta Woodruff for the warmth and love that you have shown me over the years. A great thanks goes to Anthony Della Pella and the burger group: Will and Jade Clark, Jonathan Guzman, Jay Barraza, Jenia Rousseva, and Jeremy Waters, for all laughs and good times in graduate school.
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  • Quarks and Their Discovery
    Quarks and Their Discovery Parashu Ram Poudel Department of Physics, PN Campus, Pokhara Email: [email protected] Introduction charge (e) of one proton. The different fl avors of Quarks are the smallest building blocks of matter. quarks have different charges. The up (u), charm They are the fundamental constituents of all the (c) and top (t) quarks have electric charge +2e/3 hadrons. They have fractional electronic charge. and the down (d), strange (s) and bottom (b) quarks Quarks never exist alone in nature. They are always have charge -e/3; -e is the charge of an electron. The found in combination with other quarks or antiquark masses of these quarks vary greatly, and of the six, in larger particle of matter. By studying these larger only the up and down quarks, which are by far the particles, scientists have determined the properties lightest, appear to play a direct role in normal matter. of quarks. Protons and neutrons, the particles that make up the nuclei of the atoms consist of quarks. There are four forces that act between the quarks. Without quarks there would be no atoms, and without They are strong force, electromagnetic force, atoms, matter would not exist as we know it. Quarks weak force and gravitational force. The quantum only form triplets called baryons such as proton and of strong force is gluon. Gluons bind quarks or neutron or doublets called mesons such as Kaons and quark and antiquark together to form hadrons. The pi mesons. Quarks exist in six varieties: up (u), down electromagnetic force has photon as quantum that (d), charm (c), strange (s), bottom (b), and top (t) couples the quarks charge.
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  • PARTICLE DECAYS the First Kaons from the New DAFNE Phi-Meson
    PARTICLE DECAYS K for KLi The first kaons from the new DAFNE phi-meson factory at Frascati underline a fascinating chapter in the evolution of particle physics. As reported in the June issue (p7), in mid-April the new DAFNE phi-meson factory at Frascati began operation, with the KLOE detector looking at the physics. The DAFNE electron-positron collider operates at a total collision energy of 1020 MeV, the mass of the phi- meson, which prefers to decay into pairs of kaons.These decays provide a new stage to investigate CP violation, the subtle asymmetry that distinguishes between mat­ ter and antimatter. More knowledge of CP violation is the key to an increased understanding of both elemen­ tary particles and Big Bang cosmology. Since the discovery of CP violation in 1964, neutral kaons have been the classic scenario for CP violation, produced as secondary beams from accelerators. This is now changing as new CP violation scenarios open up with B particles, containing the fifth quark - "beauty", "bottom" or simply "b" (June p22). Although still on the neutral kaon beat, DAFNE offers attractive new experimental possibilities. Kaons pro­ duced via electron-positron annihilation are pure and uncontaminated by background, and having two kaons produced coherently opens up a new sector of preci­ sion kaon interferometry.The data are eagerly awaited. Strange decay At first sight the fact that the phi prefers to decay into pairs of kaons seems strange. The phi (1020 MeV) is only slightly heavier than a pair of neutral kaons (498 MeV each), and kinematically this decay is very constrained.
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  • Spinorial Regge Trajectories and Hagedorn-Like Temperatures
    EPJ Web of Conferences will be set by the publisher DOI: will be set by the publisher c Owned by the authors, published by EDP Sciences, 2016 Spinorial Regge trajectories and Hagedorn-like temperatures Spinorial space-time and preons as an alternative to strings Luis Gonzalez-Mestres1;a 1Megatrend Cosmology Laboratory, John Naisbitt University, Belgrade and Paris Goce Delceva 8, 11070 Novi Beograd, Serbia Abstract. The development of the statistical bootstrap model for hadrons, quarks and nuclear matter occurred during the 1960s and the 1970s in a period of exceptional theo- retical creativity. And if the transition from hadrons to quarks and gluons as fundamental particles was then operated, a transition from standard particles to preons and from the standard space-time to a spinorial one may now be necessary, including related pre-Big Bang scenarios. We present here a brief historical analysis of the scientific problematic of the 1960s in Particle Physics and of its evolution until the end of the 1970s, including cos- mological issues. Particular attention is devoted to the exceptional role of Rolf Hagedorn and to the progress of the statisticak boostrap model until the experimental search for the quark-gluon plasma started being considered. In parallel, we simultaneously expose recent results and ideas concerning Particle Physics and in Cosmology, an discuss current open questions. Assuming preons to be constituents of the physical vacuum and the stan- dard particles excitations of this vacuum (the superbradyon hypothesis we introduced in 1995), together with a spinorial space-time (SST), a new kind of Regge trajectories is expected to arise where the angular momentum spacing will be of 1/2 instead of 1.
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