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International Centre for Theoretical Physics
IC/80/62 INTERNATIONAL CENTRE FOR THEORETICAL PHYSICS QUANTUM CHROMODYNAMICS A THEORY OF THE NUCLEAR FORCE U.S. Craigie INTERNATIONAL ATOMIC ENERGY AGENCY UNITED NATIONS EDUCATIONAL, SCIENTIFIC AND CULTURAL ORGANIZATION 1980 MIRAMARE-TRIESTE IC/8O/6E International Atomic Energy Agency sad United Rations Educational Scientific and Cultural Organization IBTEHHATIOHAL CEHTHB FOR THEORETICAL PHYSICS QUAHTUM CHROMODIHAMICS A THBORT OF TIffl KUCLEAK FORCE • H.S. Craigie tnterna.ttgp«l Centre for Theoretical Phyaics, Trieste, Italy, and Ietltuto IFuiotude dl Fisiea Kucleare, Sezlone dl Trieste, Italy. MHUHHB- TRIESTE June l?60 aliven at tJse Int#rM*iotial SuB»er College on Physics ana Seeds, Nathiagali,Pakistan, 1&-28 Jtm« 1980, EARLY ID"Ad ON T'KK NVCLrAR F'JRCK AiO Tire uMEKOENCE OF1 THE tJCD LAGRANGIAN Let us recap a little of the early ideas on the nuclear force. [n the AIMS s, nuclear structure was thought to be described in terms of elementary protons and neutrons, which formed an isospin doublet 5 =| P\ vith I, = -^ In these lectures I hope to give a brief outline of a possible theory for the proton aiui T = -rz for the neutron, where isospiti, i.e. SU{2) of the nuclear force and the strong interactions between elementary particles, invariance, vas the recognised symmetry of nuclear interactions at ttvit time. which ve suppose is responsible for nuclear matter. The theory I will be Further, the nuclear force between these nucleons was thought to be mediated by describing is known as quantum chromodynamics because of its association vith an elementary meson, which was seen to form an isotriplet (IT ,tt ,n ) because i new kind of nuclear charge called colour and its resemblance to quantum of its three charged states- If all these particles were elementary, then in electrodynamics. -
Higgs and Particle Production in Nucleus-Nucleus Collisions
Higgs and Particle Production in Nucleus-Nucleus Collisions Zhe Liu Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Graduate School of Arts and Sciences Columbia University 2016 c 2015 Zhe Liu All Rights Reserved Abstract Higgs and Particle Production in Nucleus-Nucleus Collisions Zhe Liu We apply a diagrammatic approach to study Higgs boson, a color-neutral heavy particle, pro- duction in nucleus-nucleus collisions in the saturation framework without quantum evolution. We assume the strong coupling constant much smaller than one. Due to the heavy mass and colorless nature of Higgs particle, final state interactions are absent in our calculation. In order to treat the two nuclei dynamically symmetric, we use the Coulomb gauge which gives the appropriate light cone gauge for each nucleus. To further eliminate initial state interactions we choose specific prescriptions in the light cone propagators. We start the calculation from only two nucleons in each nucleus and then demonstrate how to generalize the calculation to higher orders diagrammatically. We simplify the diagrams by the Slavnov-Taylor-Ward identities. The resulting cross section is factorized into a product of two Weizsäcker-Williams gluon distributions of the two nuclei when the transverse momentum of the produced scalar particle is around the saturation momentum. To our knowledge this is the first process where an exact analytic formula has been formed for a physical process, involving momenta on the order of the saturation momentum, in nucleus-nucleus collisions in the quasi-classical approximation. Since we have performed the calculation in an unconventional gauge choice, we further confirm our results in Feynman gauge where the Weizsäcker-Williams gluon distribution is interpreted as a transverse momentum broadening of a hard gluons traversing a nuclear medium. -
Baryon Number Fluctuation and the Quark-Gluon Plasma
Baryon Number Fluctuation and the Quark-Gluon Plasma Z. W. Lin and C. M. Ko Because of the fractional baryon number Using the generating function at of quarks, baryon and antibaryon number equilibrium, fluctuations in the quark-gluon plasma is less than those in the hadronic matter, making them plausible signatures for the quark-gluon plasma expected to be formed in relativistic heavy ion with g(l) = ∑ Pn = 1 due to normalization of collisions. To illustrate this possibility, we have the multiplicity probability distribution, it is introduced a kinetic model that takes into straightforward to obtain all moments of the account both production and annihilation of equilibrium multiplicity distribution. In terms of quark-antiquark or baryon-antibaryon pairs [1]. the fundamental unit of baryon number bo in the In the case of only baryon-antibaryon matter, the mean baryon number per event is production from and annihilation to two mesons, given by i.e., m1m2 ↔ BB , we have the following master equation for the multiplicity distribution of BB pairs: while the squared baryon number fluctuation per baryon at equilibrium is given by In obtaining the last expressions in Eqs. (5) and In the above, Pn(ϑ) denotes the probability of ϑ 〈σ 〉 (6), we have kept only the leading term in E finding n pairs of BB at time ; G ≡ G v 〈σ 〉 corresponding to the grand canonical limit, and L ≡ L v are the momentum-averaged cross sections for baryon production and E 1, as baryons and antibaryons are abundantly produced in heavy ion collisions at annihilation, respectively; Nk represents the total number of particle species k; and V is the proper RHIC. -
Astro-Ph/0410417V1 18 Oct 2004 Nwihteeaen Tbeconfigurations
Preon stars: a new class of cosmic compact objects J. Hansson∗ & F. Sandin† Department of Physics, Lule˚aUniversity of Technology, SE-971 87 Lule˚a, Sweden In the context of the standard model of particle physics, there is a definite upper limit to the density of stable compact stars. However, if a more fundamental level of elementary particles exists, in the form of preons, stability may be re-established beyond this limiting density. We show that a degenerate gas of interacting fermionic preons does allow for stable compact stars, with densities far beyond that in neutron stars and quark stars. In keeping with tradition, we call these objects “preon stars”, even though they are small and light compared to white dwarfs and neutron stars. We briefly note the potential importance of preon stars in astrophysics, e.g., as a candidate for cold dark matter and sources of ultra-high energy cosmic rays, and a means for observing them. PACS numbers: 12.60.Rc - 04.40.Dg - 97.60.-s - 95.35.+d I. INTRODUCTION The three different types of compact objects traditionally considered in astrophysics are white dwarfs, neutron stars (including quark and hybrid stars), and black holes. The first two classes are supported by Fermi pressure from their constituent particles. For white dwarfs, electrons provide the pressure counterbalancing gravity. In neutron stars, the neutrons play this role. For black holes, the degeneracy pressure is overcome by gravity and the object collapses indefinitely, or at least to the Planck density. arXiv:astro-ph/0410417v1 18 Oct 2004 The distinct classes of degenerate compact stars originate directly from the properties of gravity, as was made clear by a theorem of Wheeler and collaborators in the mid 1960s [1]. -
Fully Strange Tetraquark Sss¯S¯ Spectrum and Possible Experimental Evidence
PHYSICAL REVIEW D 103, 016016 (2021) Fully strange tetraquark sss¯s¯ spectrum and possible experimental evidence † Feng-Xiao Liu ,1,2 Ming-Sheng Liu,1,2 Xian-Hui Zhong,1,2,* and Qiang Zhao3,4,2, 1Department of Physics, Hunan Normal University, and Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, Changsha 410081, China 2Synergetic Innovation Center for Quantum Effects and Applications (SICQEA), Hunan Normal University, Changsha 410081, China 3Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China 4University of Chinese Academy of Sciences, Beijing 100049, China (Received 21 August 2020; accepted 5 January 2021; published 26 January 2021) In this work, we construct 36 tetraquark configurations for the 1S-, 1P-, and 2S-wave states, and make a prediction of the mass spectrum for the tetraquark sss¯s¯ system in the framework of a nonrelativistic potential quark model without the diquark-antidiquark approximation. The model parameters are well determined by our previous study of the strangeonium spectrum. We find that the resonances f0ð2200Þ and 2340 2218 2378 f2ð Þ may favor the assignments of ground states Tðsss¯s¯Þ0þþ ð Þ and Tðsss¯s¯Þ2þþ ð Þ, respectively, and the newly observed Xð2500Þ at BESIII may be a candidate of the lowest mass 1P-wave 0−þ state − 2481 0þþ 2440 Tðsss¯s¯Þ0 þ ð Þ. Signals for the other ground state Tðsss¯s¯Þ0þþ ð Þ may also have been observed in PC −− the ϕϕ invariant mass spectrum in J=ψ → γϕϕ at BESIII. The masses of the J ¼ 1 Tsss¯s¯ states are predicted to be in the range of ∼2.44–2.99 GeV, which indicates that the ϕð2170Þ resonance may not be a good candidate of the Tsss¯s¯ state. -
Quark-Lepton Unification and Proton Decay
\\£ IC/80/72 INTERNATIONAL CENTRE FOR •2t i / -Tr/ THEORETICAL PHYSICS QUARK-LEPTON UNIFICATION AND PROTON DECAY Jogesh C. Pati and Abdus Salam INTERNATIONAL ATOMIC ENERGY AGENCY UNITED NATIONS EDUCATIONAL, SCIENTIFIC AND CULTURAL ORGANIZATION 1980 MIRAMARE-TRIESTE IC/60/72 QUABK-LEFTON UNIFICATION AND PROTON DECAY I. INTRODUCTION Jogesh C. Pati The hypothesis of prnncS unification servinR to unify all basic particles - quarks and leptons - and their force:; - weak, International Centre for Theoretical Physics, Trieste, Italy, electromagnetic as well as strong - stands at present primarily and on its aesthetic merits. It gives the flavour of synthesis in that it provides a rationale for the existence of quarks and Department of Physics, University of Maryland, College Park, leptons by assigning the two sets of particles to one multiplet + Maryland, USA, of a gauge symmetry G. It derives their forces through one principle-gauge unification. and With quarks and leptons in one multiplet of a local sponta- neously broken gauge symmetry G, baryon and lepton number conserv- ation cannot be absolute. This line of reasoning had led us to Abdiis Salam suggest in 1973 that the lightest baryon - the proton - must ultimately decay into leptons 2. Theoretical considerations International Centre for Theoretical Physics, Trieste, Italy, suggest a lifetime for the proton in the ran^e of 102° to 1033 a and years "5. Its decay modes and corresponding branching ratios depend In general upon the details of the structure of the symmetry Imperial College, London, England. Kroup and its breaking Dattern. What is worth noticing »t this Junction Is that studies of (i) proton decay modes, (il) n-n oscillation (iii) neutrinoless double 6-deeay and (iv) the weak angle T sin26y are perhaps the only effective tools we would have for sometiae to probe into the underlying design of grand unification. -
The Maxwell-Cassano Equations of an Electromagnetic-Nuclear Field Yields the Fermion & Hadron Architecture
ISSN: 2639-0108 Research Article Advances in Theoretical & Computational Physics The Maxwell-Cassano Equations of an Electromagnetic-nuclear Field Yields the Fermion & Hadron Architecture Claude Michael Cassano *Corresponding author Claude Michael Cassano, Santa Clara, California, USA; E-mail: cloudmichael@ Santa Clara, California, USA hotmail.com Submitted: 16 July 2019; Accepted: 23 July 2019; Published: 05 Aug 2019 Abstract The Helmholtzian operator and factorization, via the Maxwell-Cassano equations yields a fermion architecture table equivalent to that of the standard model and lead to linear transformation groups of the mesons and baryons, respectively; plus a straightforward elementary description of quark colour based on integral indices: 1,0,1, rather than the subjective, correlative explanation using: {R,G,B;Y} indexes. keywords: Helmholtzian, Klein-Gordon equation, electromag- where: netism, preon, elementary particles, standard model, elementary (2) particle, particle interactions, fermions, leptons, quarks, hadrons, mesons, baryons, Pauli matrices, Gell-Mann matrices, Hermitian (3) matrices, Lie algebra, su(2), Yukawa potential Similarly, mass-generalized electric and magnetic potentials for the Introduction Helmholtzian operator factorization : Using the principles of the analysis of a linear function of a linear variable [1], constuctive algebras developed using the weighted matrix product [2] leads to the d’Alembertian operator and it’s factorization [3], and a space with all smooth functions satisfying Maxwell’s equations [4] [5] [6] [7]. This leads to the Helmholtzian operator and factorization[8], and a space in which all smooth functions satisfy the Maxwell-Cassano equations[9] (which generalizes both Maxwell’s equations and the Dirac equation [10] [11] [12]) - a linearization of the Klein-Gordon equations [13] [14] [12]. -
Pages from C13-03-02 3.Pdf
The GIM Mechanism: origin, predictions and recent uses Luciano Maiani CERN, Geneva, Switzerland Dipartimento di Fisica, Universita di Roma La Sapienza, Roma, Italy The GIM Mechanism was introduced by Sheldon L. Glashow, John Iliopoulos and Luciano Maiani in 1970) to explain the suppression of Delta S=l, 2 neutral current processes and is an important element of the unified theories of the weak and electromagnetic interactions. Origin, predictions and uses of the GIM Mechanism are illustrated. Flavor changing neutral current processes (FCNC) represent today an important benchmark for the Standard Theory and give strong limitations to theories that go beyond ST in the fewTe V region. Ideas on the ways constraints on FCNC may be imposed are briefly described. 1 Setting the scene The final years of the sixties marked an important transition period for the physics of elementary particles. Two important discoveries made in the early sixties, quarks and Cabibbo theory, had been consolidated by a wealth of new data and there was the feeling that a more complete picture of the strong and of the electro-weak interactions could be at hand. The quark model of hadrons introduced by M. Gell-Mann 1 and G. Zweig2 explained neatly the spectrum of the lowest lying mesons and baryons as qij and qqq states, respectively, with: (1) and electric charges Q 2/3 1/3 /3 respectively. 1 Doubts persisted on= quarks, - being, - real, physical entities or rather a simple mathematical tool to describe hadrons. This was due to the symmetry puzzle, namely the fact that one had to assume an overall symmetric configuration of the three quarks to describe the spin-charge structure of the baryons, rather than the antisymmetric configuration required by the fermion nature of physical, spin 1/2, quark$'. -
Arxiv:0810.4453V1 [Hep-Ph] 24 Oct 2008
The Physics of Glueballs Vincent Mathieu Groupe de Physique Nucl´eaire Th´eorique, Universit´e de Mons-Hainaut, Acad´emie universitaire Wallonie-Bruxelles, Place du Parc 20, BE-7000 Mons, Belgium. [email protected] Nikolai Kochelev Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna, Moscow region, 141980 Russia. [email protected] Vicente Vento Departament de F´ısica Te`orica and Institut de F´ısica Corpuscular, Universitat de Val`encia-CSIC, E-46100 Burjassot (Valencia), Spain. [email protected] Glueballs are particles whose valence degrees of freedom are gluons and therefore in their descrip- tion the gauge field plays a dominant role. We review recent results in the physics of glueballs with the aim set on phenomenology and discuss the possibility of finding them in conventional hadronic experiments and in the Quark Gluon Plasma. In order to describe their properties we resort to a va- riety of theoretical treatments which include, lattice QCD, constituent models, AdS/QCD methods, and QCD sum rules. The review is supposed to be an informed guide to the literature. Therefore, we do not discuss in detail technical developments but refer the reader to the appropriate references. I. INTRODUCTION Quantum Chromodynamics (QCD) is the theory of the hadronic interactions. It is an elegant theory whose full non perturbative solution has escaped our knowledge since its formulation more than 30 years ago.[1] The theory is asymptotically free[2, 3] and confining.[4] A particularly good test of our understanding of the nonperturbative aspects of QCD is to study particles where the gauge field plays a more important dynamical role than in the standard hadrons. -
Observation of Global Hyperon Polarization in Ultrarelativistic Heavy-Ion Collisions
Available online at www.sciencedirect.com Nuclear Physics A 967 (2017) 760–763 www.elsevier.com/locate/nuclphysa Observation of Global Hyperon Polarization in Ultrarelativistic Heavy-Ion Collisions Isaac Upsal for the STAR Collaboration1 Ohio State University, 191 W. Woodruff Ave., Columbus, OH 43210 Abstract Collisions between heavy nuclei at ultra-relativistic energies form a color-deconfined state of matter known as the quark-gluon plasma. This state is well described by hydrodynamics, and non-central collisions are expected to produce a fluid characterized by strong vorticity in the presence of strong external magnetic fields. The STAR Collaboration at Brookhaven National Laboratory’s√ Relativistic Heavy Ion Collider (RHIC) has measured collisions between gold nuclei at center of mass energies sNN = 7.7 − 200 GeV. We report the first observation of globally polarized Λ and Λ hyperons, aligned with the angular momentum of the colliding system. These measurements provide important information on partonic spin-orbit coupling, the vorticity of the quark-gluon plasma, and the magnetic field generated in the collision. 1. Introduction Collisions of nuclei at ultra-relativistic energies create a system of deconfined colored quarks and glu- ons, called the quark-gluon plasma (QGP). The large angular momentum (∼104−5) present in non-central collisions may produce a polarized QGP, in which quarks are polarized through spin-orbit coupling in QCD [1, 2, 3]. The polarization would be transmitted to hadrons in the final state and could be detectable through global hyperon polarization. Global hyperon polarization refers to the phenomenon in which the spin of Λ (and Λ) hyperons is corre- lated with the net angular momentum of the QGP which is perpendicular to the reaction plane, spanned by pbeam and b, where b is the impact parameter vector of the collision and pbeam is the beam momentum. -
Charm and Strange Quark Contributions to the Proton Structure
Report series ISSN 0284 - 2769 of SE9900247 THE SVEDBERG LABORATORY and \ DEPARTMENT OF RADIATION SCIENCES UPPSALA UNIVERSITY Box 533, S-75121 Uppsala, Sweden http://www.tsl.uu.se/ TSL/ISV-99-0204 February 1999 Charm and Strange Quark Contributions to the Proton Structure Kristel Torokoff1 Dept. of Radiation Sciences, Uppsala University, Box 535, S-751 21 Uppsala, Sweden Abstract: The possibility to have charm and strange quarks as quantum mechanical fluc- tuations in the proton wave function is investigated based on a model for non-perturbative QCD dynamics. Both hadron and parton basis are examined. A scheme for energy fluctu- ations is constructed and compared with explicit energy-momentum conservation. Resulting momentum distributions for charniand_strange quarks in the proton are derived at the start- ing scale Qo f°r the perturbative QCD evolution. Kinematical constraints are found to be important when comparing to the "intrinsic charm" model. Master of Science Thesis Linkoping University Supervisor: Gunnar Ingelman, Uppsala University 1 kuldsepp@tsl .uu.se 30-37 Contents 1 Introduction 1 2 Standard Model 3 2.1 Introductory QCD 4 2.2 Light-cone variables 5 3 Experiments 7 3.1 The HERA machine 7 3.2 Deep Inelastic Scattering 8 4 Theory 11 4.1 The Parton model 11 4.2 The structure functions 12 4.3 Perturbative QCD corrections 13 4.4 The DGLAP equations 14 5 The Edin-Ingelman Model 15 6 Heavy Quarks in the Proton Wave Function 19 6.1 Extrinsic charm 19 6.2 Intrinsic charm 20 6.3 Hadronisation 22 6.4 The El-model applied to heavy quarks -
Discovery of Gluon
Discovery of the Gluon Physics 290E Seminar, Spring 2020 Outline – Knowledge known at the time – Theory behind the discovery of the gluon – Key predicted interactions – Jet properties – Relevant experiments – Analysis techniques – Experimental results – Current research pertaining to gluons – Conclusion Knowledge known at the time The year is 1978, During this time, particle physics was arguable a mature subject. 5 of the 6 quarks were discovered by this point (the bottom quark being the most recent), and the only gauge boson that was known was the photon. There was also a theory of the strong interaction, quantum chromodynamics, that had been developed up to this point by Yang, Mills, Gell-Mann, Fritzsch, Leutwyler, and others. Trying to understand the structure of hadrons. Gluons can self-interact! Theory behind the discovery Analogous to QED, the strong interaction between quarks and gluons with a gauge group of SU(3) symmetry is known as quantum chromodynamics (QCD). Where the force mediating particle is the gluon. In QCD, we have some quite particular features such as asymptotic freedom and confinement. 4 α Short range:V (r) = − s QCD 3 r 4 α Long range: V (r) = − s + kr QCD 3 r (Between a quark and antiquark) Quantum fluctuations cause the bare color charge to be screened causes coupling strength to vary. Features are important for an understanding of jet formation. Theory behind the discovery John Ellis postulated the search for the gluon through bremsstrahlung radiation in electron- proton annihilation processes in 1976. Such a process will produce jets of hadrons: e−e+ qq¯g Furthermore, Mary Gaillard, Graham Ross, and John Ellis wrote a paper (“Search for Gluons in e+e- Annihilation.”) that described that the PETRA collider at DESY and the PEP collider at SLAC should be able to observe this process.