DOCSLIB.ORG

(Max Planck Institute Für Physik) 1St Lecture

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
(Max Planck Institute Für Physik) 1St Lecture QCD Giulia Zanderighi (Max Planck Institute für Physik) 1st Lecture ESHEP School September 2019 Today’s high energy colliders Today’s high energy physics program relies mainly on results from Today’s high energy colliders Collider Process Today’s high statusenergy colliders + T-oday’s high energy colliders Collider LEP/LEP2Process setaetus Today’s high1989-2000energy colliders Today’s chighurrenenergyt and ucpolliderscoming ex- Hera e±p Today’s high1992-2007energy colliders HERCAoll(idAe&r B) Preo±cpess rsutanntuinsg periments collide protons Collider TevatronProcess statupps curre1983-2011nt and upcoming ex- Collider Process status current and upcoming ex- THeERvCaotrlAloidn(eAr(I&&B)II) Proceep±sp¯sp startuunsning cpuerrrimenetntsancdolluidpecopmroitongnsex- HERA (A & B)LHC-e ±Runp I runninppg cpuerrrimenetntsa2010-2012ncadolllluidipnecvopomrolvitonegnQseCDx- Collider Process status THeERvatrALoHn(AC(I&&B)II) ep±p¯p starurtsnn2in0g07 pe⇒riments collide protons THeERvatrAon(A(I&&B)II) ep±p¯p running perimcuernretsnctolalinded puroptoconms ing ex- LHC- Run II pp astartedll inavlloilnv 2015evoQlvCDe QCD THeERvatrALoHn(AC(I&&B)II) ep±p¯p starurtsnn2in0g07 pe⇒riments collide protons TevatrLoHnC(I & II) pp¯ starurtsnn2in0g07 ⇒ all involve QCD LEPHER highA: m precisionainly mea measurementssurements of pa ofrto masses,n denaslilti couplings,iensvaonlvdedQiffr CDEWacti oparametersn ... TevaLtrHLoHCnC(I & II) pppp¯ stasrtstarur2tsn0n02i7n0g07 ⇒ ⇒ Hera: mainly measurements of proton structureal l/ inpartonvolve densitiesQCD HTHEReERLvA:HatrA:Cmonma:inamliynalmyinemlyaesdpuaipsrsecumoreveemnrtseysntaotsffrptsthoafer2top0toan0rp7todaennsddietirene⇒sslaiatitenedds mdainffredaasdcutiiffrroenamcetionnts THTevatron:eLTHERveHERavCtrA:aotrA:dnmoe:nmasm :imainlyngaamlniyinnaelmlyidynemldtoya isdiscoveryesdcuaiosrsevcuemorreveyemnortseyf nthooftsfef pthtoptooaferptopto aaandnnrpdtodaern nemanyslddaietiterenedssla imQCDatiteneeddsasmdauinffr ermeasurementsdeaamsdcuetiiffrronentsamcetionnts LTLHCeHLTveHCERavCtradd odesignedtrA:eidsnsoec:ingmsom:nivgaaemeniidnrnaelthltoyidyn toemldtoyiHsedcaiigossvgcueosrrevyaemnoredyf nthomtsefethtooafespputoaarenrpdtoit’arnsnelddpaerteronedpslaeimtiteretiedseassmaunerdeamsdueiffrrnetsamcetionnts LHLTediscoverHCvdCaiddustreincdssorecaivngsove:nivegrem elnththedrpaeethtooidn sHelHiggstosyigiHbdgiligsesgcap os[donenhvdayesnmridycesoma infsbeuthe arRunyeesouintot’rsde pI]pthit’arosenpdpSMerroetipelaestertidesmeasurements discover the Higgs and measure it’s properties unravelundurinasrvcaeovl vepossiblepelorpsthossiebsleiHb pilgeBSMhgypsshiacy sphysicssnidbcesmyboeenayd s[elusiveouthnrde thSMit’sep SMuprop toer tinow]es LHOuC rdeasbigilintyedtotodiscover new particles and to measure their unravel possible physics beyond th2e SM duinsrcaovveelrpthosesiHbilgegpshaysnidcsmbeeaysounrde thit’sepSMroperties OuOuprrorapbeairlbitityielitystolitomdistedcidosvcbeoyrvthenreewnqeupwaalriptitycaloretifscolaeunsrduantonddemrtosetaasmnuderieansgthuoreefirQCtheDir Ouprorpuenarrbtiaielvitysellitopmoitesdsidsibcbloyevtheprheynqseuiwcasliptybaeorytifocolneudsr uthanneddeSMrtostamndeiansguoref QCtheDir Ouprorpearbtiielitys litomitedidscboyvtherenqeuwaliptyaortifcoleusr uannddertostamndeiansguoref QCtheDir properties limited by the quality of our understanThde oinne-lgoop oamfplitQCude forDsix gluon scattering - April 2006 – p.2/20 Ouprorpearbtiielitys litomitedidscboyvtherenqeuwaliptyaortifcoleusr uaTnhenodndee-loorptosamtaplitumnde dfoer siainx gsgluoun osrcaeftterQCingth- AperDil 2i0r06 – p.2/20 The one-loop amplitude for six gluon scattering - April 2006 – p.2/20 properties limited by the quality of our uTnhe odnee-loorpsamtaplitunde dfor siinx ggluon oscaftterQCing - AprDil 2006 – p.2/20 The one-loop amplitude for six gluon scattering - April 2006 – p.2/20 The one-loop amplitude for six gluon scattering - April 2006 – p.2/20 Today’s status of particle physics • The Higgs boson: the last missing ingredient of the Standard Model of particle physics • The SM is a consistent theory up to very high energy, but it can not be a complete theory because of many theory and experimental puzzles (Dark matter and dark energy, neutrino masses, flavour physics, hierarchy problem, no theory of quantum gravity…) The days of guaranteed discoveries or no-lose theorems are over. Progress will be driven by LHC data. The LHC program in the coming decades will focus on • Direct searches: production of new (heavy status) … • Indirect searches: Higgs couplings and branchings, rare decay modes … • Consistency tests: precision electroweak data 3 Today’s status of particle physics Improving our theoretical description of data crucial to enhance sensitivity when looking for new physics. Example: extraction of Higgs couplings limited by theory uncertainties Sharpen the tools ⇒ get more accurate predictions ⇒ get improved indirect sensitivity to New Physics (which would modify SM couplings) 4 Propose of these lectures In these lectures: perturbative QCD as a tool for precision QCD at colliders • Introduction to QCD (or refresh your knowledge of QCD) • Basic concepts which appear over and over in different contexts • Understand the terminology • Recent developments in the field 5 Some bibliography • A QCD primer G. Altarelli (TASI lectures 2002) hep-ph/0204179 • QCD and Collider Physics (a.k.a. The Pink Book) R.K. Ellis, W. J. Stirling, B. R. Webber, Cambridge University Press (1999) • Foundations of Quantum Chromodynamics T. Muta, World Scientific (1998) • Quantum Chromodynamics: High Energy Experiments and Theory G. Dissertori, I. Knowles, M. Schmelling, International Series of Monograph on Physics (2009) • The theory of quark and gluon interactions F. J. Yndurain, Springer-Verlag (1999) • Gauge Theory and Elementary Particle Physics T. Cheng and L. Li, Oxford Science Publications (1984) • The Black Book of Quantum Chromodynamics: A Primer for the LHC Era J. Campbell, J, Huston, F. Krauss (2018) • many write-ups of QCD lectures given at previous CERN schools ... 6 The beginning: the eightfold way Organise hadron spectrum to manifest some symmetry-pattern One hadron missing, but predicted following the pattern But what is the reason for this pattern? 7 Quarks (1964) Gell-Mann and Zweig propose the existence of elementary spin 1/2 particles (the quarks). Three types of quarks, up, down, strange (plus their antiparticles) can explain the composition of all observed hadrons 8 First experimental evidence for colour I. Existence of Δ++ particle: particle with three up quarks of the same spin and with symmetric spacial wave function. Without an additional quantum number Pauli’s principle would be violated ⇒ color quantum number u1 u2 u3 ++ ∆ = ijkuiujuk New quantum number solves spin-statistics problem (wave function becomes asymmetric) 9 U †U = UU † = 1 det(U) = 1 ψ∗ψ U ∗ ψ U ψ = ψ∗ψ i i → ij j ik k k k !i !ijk !k ψiψjψk U ∗ Ujj Ukk ψi ψj ψk = ψi ψj ψk First→ experimentalii′ ′ ′ ′ evidence′ ′ for′ ′ colour′ !ijk ijk!i′j′k′ i!′j′k′ n n = n 3 with n integer II.R-ratio: ratioq of− (eq¯+e- → ·hadrons)/(e+e- → µ+µ-) e+ p1 + e e− hadrons 2 R + → + Nc Qf ≡ e e− µ µ− ∝ → !f e− p2 Experimental data confirms Nc = 3. (Will come back to R later.) Color becomes the charge of strong interaction. Interaction is so strong, that the only observed hadrons in nature are those where quarks are combined in colour singlet states Colour SU(3) is an exact symmetry of nature 10 1 QCD Model for strong interactions: non-abelian gauge theory SU(3) U †U = UU † = 1 det(U) = 1 ψ∗ψ U ∗ ψ U ψ = ψ∗ψ Hadron spectrum fully classifiedi i → withij thej ik followingk assumptionsk k !i !ijk !k - hadrons (baryons,mesons): made of spin 1/2 quarks ψ ψ ψ U ∗ U U ψ ψ ψ = ψ ψ ψ i j k ii′ jj′ kk′ i′ j′ k′ i′ j′ k′ ijk → ijki j k i j k - each! quark of a given! ′flavour′ ′ comes in Nc=3 colors!′ ′ ′ + e e− hadrons color SU(3) is an exactR symmetry→ Q2 - ≡ e+e µ+mu ∝ − → − - hadrons are colour neutral, i.e. colour singlet under SU(3) - observed hadrons are colour neutral ⇒ hadrons have integer charge 11 1 Color singlet hadrons Quarks can be combined in 2 elementary ways into color singlets of the SUc(3) group Mesons (bosons, e.g. pion ...) ψ∗ψ U ∗ U ψ ψ = ψ∗ψ i i → ij ik j k k k i ijk k Baryons (fermions, e.g. proton, neutrons ...) ⇥ ⇥ ⇥ U U U ⇥ ⇥ ⇥ = det(U)⇥ ⇥ ⇥ ijk i j k → ijk ii jj kk i j k ijk i j k ijk iijjkk ijk 12 Quark mass spectrum 100 up-type quarks t 1 down-type quarks u c t 10− b 2/3 up charm top 2 c + 10− top /m q 3 s 10− d s b m 1/3 electric charge down strange bottom − 4 10− d u 5 1st 2nd 3rd 10− quark generation 6 10− charge 2/3 up charm top mass= few MeV ~1.6 GeV ~172 GeV charge -1/3 down strange bottom mass = few MeV ~100 MeV ~5 GeV 13 The R-ratio: comparison to data Renormalisation group QCD beta function Short-distance observables 2 Comparison of RˆR tochangesexperi mcrossingental d aquarkta flavour thresholds R = Nc eq q 10 2 φ u, d, s ω 3 loop pQCD 10 Naive quark model ρ ρ′ nf =3 R =2 1 Sum of exclusive Inclusive measurements measurements -1 10 0.5 1 1.5 2 2.5 3 7 ψ(2S) J/ψ ψ4160 c 6 Mark-I Mark-I + LGW ψ4415 Mark-II ψ4040 5 PLUTO ψ3770 R DASP 10 4 Crystal Ball BES nf =3 4 R = 3 → 3 2 3 3.5 4 4.5 5 8 Υ(1S) Υ(3S) b 7 Υ(2S) Υ(4S) 6 5 11 4 nf =4 5 R = 3 ARGUS CLEO CUSB DHHM → 3 MD-1 2 Crystal Ball CLEO II DASP LENA 9.5 10 10.5 11 √s [GeV] 14 Andrea Banfi Lecture 2 QCD matter sector e− e− u 2/3 up γ∗ + q d s q 1/3 electric charge down strange − p X 1st 2nd Feynman diagram describing DIS of an quark generation electron on a proton • The light quark's existence was validated by the SLAC's deep
Load more

Recommended publications
  • Two Tests of Isospin Symmetry Break
    THE ISOBARIC MULTIPLET MASS EQUATION AND ft VALUE OF THE 0+ 0+ FERMI TRANSITION IN 32Ar: TWO TESTS OF ISOSPIN ! SYMMETRY BREAKING A Dissertation Submitted to the Graduate School of the University of Notre Dame in Partial Ful¯llment of the Requirements for the Degree of Doctor of Philosophy by Smarajit Triambak Alejandro Garc¶³a, Director Umesh Garg, Director Graduate Program in Physics Notre Dame, Indiana July 2007 c Copyright by ° Smarajit Triambak 2007 All Rights Reserved THE ISOBARIC MULTIPLET MASS EQUATION AND ft VALUE OF THE 0+ 0+ FERMI TRANSITION IN 32Ar: TWO TESTS OF ISOSPIN ! SYMMETRY BREAKING Abstract by Smarajit Triambak This dissertation describes two high-precision measurements concerning isospin symmetry breaking in nuclei. 1. We determined, with unprecedented accuracy and precision, the excitation energy of the lowest T = 2; J ¼ = 0+ state in 32S using the 31P(p; γ) reaction. This excitation energy, together with the ground state mass of 32S, provides the most stringent test of the isobaric multiplet mass equation (IMME) for the A = 32, T = 2 multiplet. We observe a signi¯cant disagreement with the IMME and investigate the possibility of isospin mixing with nearby 0+ levels to cause such an e®ect. In addition, as byproducts of this work, we present a precise determination of the relative γ-branches and an upper limit on the isospin violating branch from the lowest T = 2 state in 32S. 2. We obtained the superallowed branch for the 0+ 0+ Fermi decay of ! 32Ar. This involved precise determinations of the beta-delayed proton and γ branches. The γ-ray detection e±ciency calibration was done using pre- cisely determined γ-ray yields from the daughter 32Cl nucleus from an- other independent measurement using a fast tape-transport system at Texas Smarajit Triambak A&M University.
    [Show full text]
  • Lecture 5 Symmetries
    Lecture 5 Symmetries • Light hadron masses • Rotations and angular momentum • SU(2 ) isospin • SU(2 ) flavour • Why are there 8 gluons ? • What do we mean by colourless ? FK7003 1 Where do the light hadron masses come from ? Proton (uud ) mass∼ 1 GeV. Quark Q Mass (GeV) π + ud mass ∼ 130 MeV (e) () u- up 2/3 0.003 ∼ u, d mass 3-5 MeV. d- down -1/3 0.005 ⇒ The quarks account for a small fraction of the light hadron masses. [Light hadron ≡ hadron made out of u, d quarks.] Where does the rest come from ? FK7003 2 Light hadron masses and the strong force Meson Baryon Light hadron masses arise from ∼ the stron g field and quark motion. ⇒ Light hadron masses are an observable of the strong force. FK7003 3 Rotations and angular momentum A spin-1 particle is in spin-up state i.e . angular momentum along an 2 ℏ 1 an arbitrarily chosen +z axis is and the state is χup = . 2 0 The coordinate system is rotated π around y-axis by transformatiy on U 1 0 ⇒ UUχup= = = χ down 0 1 spin-up spin-down No observable will change. z Eg the particle still moves in the same direction in a changing B-field regardless of how we choose the z -axis in the lab. 1 ∂B 0 ∂B 0 ∂z 1 ∂z Rotational inv ariance ⇔ angular momentum conservation ( Noether) SU(2) The group of 22(× unitary U* U = UU * = I ) matrices with det erminant 1 . SU (2) matrices ≡ set of all possible rotation s of 2D spinors in space.
    [Show full text]
  • 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].
    [Show full text]
  • Arxiv:1904.02304V2 [Hep-Lat] 4 Sep 2019 Isospin Splittings in Decuplet Baryons 2
    ADP-19-6/T1086 LTH 1200 DESY 19-053 Isospin splittings in the decuplet baryon spectrum from dynamical QCD+QED R. Horsley1, Z. Koumi2, Y. Nakamura3, H. Perlt4, D. Pleiter5;6, P.E.L. Rakow7, G. Schierholz8, A. Schiller4, H. St¨uben9, R.D. Young2 and J.M. Zanotti2 1 School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, UK 2 CSSM, Department of Physics, University of Adelaide, SA, Australia 3 RIKEN Center for Computational Science, Kobe, Hyogo 650-0047, Japan 4 Institut f¨urTheoretische Physik, Universit¨atLeipzig, 04109 Leipzig, Germany 5 J¨ulich Supercomputer Centre, Forschungszentrum J¨ulich, 52425 J¨ulich, Germany 6 Institut f¨urTheoretische Physik, Universit¨atRegensburg, 93040 Regensburg, Germany 7 Theoretical Physics Division, Department of Mathematical Sciences, University of Liverpool, Liverpool L69 3BX, UK 8 Deutsches Elektronen-Synchrotron DESY, 22603 Hamburg, Germany 9 Regionales Rechenzentrum, Universit¨atHamburg, 20146 Hamburg, Germany CSSM/QCDSF/UKQCD Collaboration Abstract. We report a new analysis of the isospin splittings within the decuplet baryon spectrum. Our numerical results are based upon five ensembles of dynamical QCD+QED lattices. The analysis is carried out within a flavour- breaking expansion which encodes the effects of breaking the quark masses and electromagnetic charges away from an approximate SU(3) symmetric point. The results display total isospin splittings within the approximate SU(2) multiplets that are compatible with phenomenological estimates. Further, new insight is gained into these splittings by separating the contributions arising from strong and electromagnetic effects. We also present an update of earlier results on the octet baryon spectrum. arXiv:1904.02304v2 [hep-lat] 4 Sep 2019 Isospin splittings in decuplet baryons 2 1.
    [Show full text]
  • 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.
    [Show full text]
  • Arxiv:1706.02588V2 [Hep-Ph] 29 Apr 2019 D D O Oeua Tts Ntehde Hr Etrw Have We Sector Candidates Charm Good Hidden the Particularly the in As Are States
    Heavy Baryon-Antibaryon Molecules in Effective Field Theory 1, 2 1, 1, Jun-Xu Lu, Li-Sheng Geng, ∗ and Manuel Pavon Valderrama † 1School of Physics and Nuclear Energy Engineering, International Research Center for Nuclei and Particles in the Cosmos and Beijing Key Laboratory of Advanced Nuclear Materials and Physics, Beihang University, Beijing 100191, China 2Institut de Physique Nucl´eaire, CNRS-IN2P3, Univ. Paris-Sud, Universit´eParis-Saclay, F-91406 Orsay Cedex, France (Dated: April 30, 2019) We discuss the effective field theory description of bound states composed of a heavy baryon and antibaryon. This framework is a variation of the ones already developed for heavy meson- antimeson states to describe the X(3872) or the Zc and Zb resonances. We consider the case of heavy baryons for which the light quark pair is in S-wave and we explore how heavy quark spin symmetry constrains the heavy baryon-antibaryon potential. The one pion exchange potential mediates the low energy dynamics of this system. We determine the relative importance of pion exchanges, in particular the tensor force. We find that in general pion exchanges are probably non- ¯ ¯ ¯ ¯ ¯ ¯ perturbative for the ΣQΣQ, ΣQ∗ ΣQ and ΣQ∗ ΣQ∗ systems, while for the ΞQ′ ΞQ′ , ΞQ∗ ΞQ′ and ΞQ∗ ΞQ∗ cases they are perturbative. If we assume that the contact-range couplings of the effective field theory are saturated by the exchange of vector mesons, we can estimate for which quantum numbers it is more probable to find a heavy baryonium state. The most probable candidates to form bound states are ¯ ¯ ¯ ¯ ¯ ¯ the isoscalar ΛQΛQ, ΣQΣQ, ΣQ∗ ΣQ and ΣQ∗ ΣQ∗ and the isovector ΛQΣQ and ΛQΣQ∗ systems, both in the hidden-charm and hidden-bottom sectors.
    [Show full text]
  • 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.
    [Show full text]
  • Isospin and Isospin/Strangeness Correlations in Relativistic Heavy Ion Collisions
    Isospin and Isospin/Strangeness Correlations in Relativistic Heavy Ion Collisions Aram Mekjian Rutgers University, Department of Physics and Astronomy, Piscataway, NJ. 08854 & California Institute of Technology, Kellogg Radiation Lab 106-38, Pasadena, Ca 91125 Abstract A fundamental symmetry of nuclear and particle physics is isospin whose third component is the Gell-Mann/Nishijima expression I Z =Q − (B + S) / 2 . The role of isospin symmetry in relativistic heavy ion collisions is studied. An isospin I Z , strangeness S correlation is shown to be a direct and simple measure of flavor correlations, vanishing in a Qg phase of uncorrelated flavors in both symmetric N = Z and asymmetric N ≠ Z systems. By contrast, in a hadron phase, a I Z / S correlation exists as long as the electrostatic charge chemical potential µQ ≠ 0 as in N ≠ Z asymmetric systems. A parallel is drawn with a Zeeman effect which breaks a spin degeneracy PACS numbers: 25.75.-q, 25.75.Gz, 25.75.Nq Introduction A goal of relativistic high energy collisions such as those done at CERN or BNL RHIC is the creation of a new state of matter known as the quark gluon plasma. This phase is produced in the initial stages of a collision where a high density ρ and temperatureT are produced. A heavy ion collision then proceeds through a subsequent expansion to lower ρ andT where the colored quarks and anti-quarks form isolated colorless objects which are the well known particles whose properties are tabulated in ref[1]. Isospin plays an important role in the classification of these particles [1,2].
    [Show full text]
  • 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.
    [Show full text]
  • Chapter 12 Charge Independence and Isospin
    Chapter 12 Charge Independence and Isospin If we look at mirror nuclei (two nuclides related by interchanging the number of protons and the number of neutrons) we find that their binding energies are almost the same. In fact, the only term in the Semi-Empirical Mass formula that is not invariant under Z (A-Z) is the Coulomb term (as expected). ↔ Z2 (Z N)2 ( 1) Z + ( 1) N a B(A, Z ) = a A a A2/3 a a − + − − P V − S − C A1/3 − A A 2 A1/2 Inside a nucleus these electromagnetic forces are much smaller than the strong inter-nucleon forces (strong interactions) and so the masses are very nearly equal despite the extra Coulomb energy for nuclei with more protons. Not only are the binding energies similar - and therefore the ground state energies are similar but the excited states are also similar. 7 7 As an example let us look at the mirror nuclei (Fig. 12.2) 3Li and 4Be, where we see that 7 for all the states the energies are very close, with the 4Be states being slightly higher because 7 it has one more proton than 3Li. All this suggests that whereas the electromagnetic interactions clearly distinguish between protons and neutrons the strong interactions, responsible for nuclear binding, are ‘charge independent’. Let us now look at a pair of mirror nuclei whose proton number and neutron number 6 6 differ by two, and also the nuclide between them. The example we take is 2He and 4Be, which are mirror nuclei. Each of these has a closed shell of two protons and a closed shell of 6 6 two neutrons.
    [Show full text]
  • Isospin Symmetry Breaking in Sd Shell Nuclei
    Num´ero d’ordre: 4446 TH ESE` pr´esent´ee `a L’Université Bordeaux I Ecole Doctorale des Sciences Physiques et de l’Ing enieure´ par Yek Wah LAM (Yi Hua LAM 藍藍藍乙乙乙華華華) Pour obtenir le grade de DOCTEUR Sp ecialit´ e´ Astrophysique, Plasmas, Nucl eaire´ Isospin Symmetry Breaking in sd Shell Nuclei Soutenue le 13 decembre 2011 tel-00777498, version 1 - 17 Jan 2013 Apr`es avis de: M. Piet Van ISACKER DR, CEA, GANIL Rapporteur externe M. Frederic NOWACKI DR, CNRS, IHPC, Strasbourg Rapporteur externe Devant la commission d’examen form´ee de: M. Bertram BLANK DR, CNRS, CEN Bordeaux-Gradignan Pr´esident M. Michael BENDER DR, CNRS, CEN Bordeaux-Gradignan Directeur de th`ese M. Van Giai NGUYEN DR, CNRS, IPN, Orsay Examinateurs M. Piet Van ISACKER DR, CEA, GANIL M. Frederic NOWACKI DR, CNRS, IHPC, Strasbourg Mme. Nadezda SMIRNOVA Maˆıtre de Conf´erences, Universit´eBordeaux I 2011 CENBG Dedicated to my beloved wife Mei Chee Chan ഋऍ޲ , and my dear son Yu Xuan Lam ᙔᒕ侍 , without whose consistent encouragement and total sacrifice, this thesis would have never been touched by the light. And dedicated to the late Peik Ching Ho Ֆᅸమ , my grandma who loved me most, tel-00777498, version 1 - 17 Jan 2013 and lost her beloved hubby during WW2, and rebuilt our family determinantly. 2 Acknowledgments As a mechanical engineering graduate, I opted not to follow the ordinary trend of graduates. Most of them have a rather easy life with high income, whereas I have chosen a different path of life – pursuing theoretical physics career – the so-called abnormal path in ordinary Malaysians perspective.
    [Show full text]
  • Chapter 16 Constituent Quark Model
    Chapter 16 Constituent Quark Model 1 Quarks are fundamental spin- 2 particles from which all hadrons are made up. Baryons consist of three quarks, whereas mesons consist of a quark and an anti-quark. There are six 2 types of quarks called “flavours”. The electric charges of the quarks take the value + 3 or 1 (in units of the magnitude of the electron charge). − 3 2 Symbol Flavour Electric charge (e) Isospin I3 Mass Gev /c 2 1 1 u up + 3 2 + 2 0.33 1 1 1 ≈ d down 3 2 2 0.33 − 2 − ≈ c charm + 3 0 0 1.5 1 ≈ s strange 3 0 0 0.5 − 2 ≈ t top + 3 0 0 172 1 ≈ b bottom 0 0 4.5 − 3 ≈ These quarks all have antiparticles which have the same mass but opposite I3, electric charge and flavour (e.g. anti-strange, anti-charm, etc.) 16.1 Hadrons from u,d quarks and anti-quarks Baryons: 2 Baryon Quark content Spin Isospin I3 Mass Mev /c 1 1 1 p uud 2 2 + 2 938 n udd 1 1 1 940 2 2 − 2 ++ 3 3 3 ∆ uuu 2 2 + 2 1230 + 3 3 1 ∆ uud 2 2 + 2 1230 0 3 3 1 ∆ udd 2 2 2 1230 3 3 − 3 ∆− ddd 1230 2 2 − 2 113 1 1 3 Three spin- 2 quarks can give a total spin of either 2 or 2 and these are the spins of the • baryons (for these ‘low-mass’ particles the orbital angular momentum of the quarks is zero - excited states of quarks with non-zero orbital angular momenta are also possible and in these cases the determination of the spins of the baryons is more complicated).
    [Show full text]