DOCSLIB.ORG

An Introduction to Heavy Flavour Physics at Hadron Machines, E+ E

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
An Introduction to Heavy Flavour Physics at Hadron Machines, E+ E PHYSICAL REVIEW LETTERS week ending PRL 98, 031802 (2007) 19 JANUARY 2007 TABLE I. Results of the fits to the t distributions. The first include their effect in the systematic uncertainties in the errors are statistical and the second errors are systematic. background fraction. Other contributions come from un- eff certainties in wrong tag fractions, the background t dis- Mode sin21 Af tribution, B0 and md. A possible fit bias is examined by K0 0:50 0:21 0:06 0:07 0:15 0:05 fitting a large number of MC events and is found to be 0 0K 0:64 0:10 0:04 0:01 0:07 0:05 small. ÿ K0K0K0 0:30 0:32 0:08 0:31 0:20 0:07 The dominant sources of systematic errors for the B0 S S S J= K0 0:642 0:031 0:017 0:018 0:021 0:014 J= K0 mode are the uncertainties in the vertex reconstruc-! tion (0.012 for sin21, 0.009 for Af), in the resolution function for the signal (0.006, 0.001), in the background quality (r>0:5) events. The sign of each t measurement 0 fraction (0.006, 0.002), in the flavor tagging (0.004, 0.003), for final states with a KL is inverted in order to combine 0 0 a possible fit bias (0.007, 0.004) and the effect of the results with KS and KL mesons. eff tagside interference (0.001, 0.009). Other contributions The dominant sources of systematic error for sin21 in amount to less than 0.001. We add each contribution in b sqq modes come from the uncertainties in the reso- ! 0 0 quadrature to obtain the total systematic uncertainty. lution function for the signal (0.03 for the B 0K For the B0 K0 mode, we observe CP violation with An introduction0 to heavy! 0 flavour physics0 mode, 0.04 for the K mode, 0.05 for the B a significance! equivalent to 5.6 standard deviations for a 0 0 0 ! KSKSKS mode) and in the background fraction+ − (0.02, Gaussian error, where the significance is calculated using at0.04, hadron 0.06). The effect machines, of f 980 K0 backgrounde e incolliders, the & elsewhere 0 the Feldman-Cousins frequentist approach [20]. The re- K0 mode (0.02) is estimated using the BES measurement 0 0 0 0 0 0 sults for B 0K , K and KSKSKS decays are all of the f0 980 line shape [18] and is included in the ! Bruce Yabsley consistent with the value of sin21 obtained from the background fraction systematic error. The dominant decay B0 J= K0 within 2 standard deviations. No direct sources for A in b sqq modes are the effects of tag- ! f !University of Sydney Particle PhysicsCP Groupviolation is observed in these decay modes. Further side interference [19] (0.02, 0.03, 0.04), the uncertainties in ARC Centre of Excellence for Particle Physicsmeasurements at the Terascale with much larger data samples are required the background fraction (0.02, 0.03, 0.05), in the vertex (http://www.coepp.org.au/)to search for new, beyond the SM, CP-violating phases in reconstruction (0.02 for all modes), and in the resolution the b s transition. function (0.02, 0.01, 0.02). We study the possible correla- We! thank the KEKB group for excellent operation of the 0 tions between Rs=b, pBCoEPPand r PDFs Annual used for Workshop,KL and accelerator, Cairns the KEK cryogenics group for efficient sole- K0 0 L, which are neglected in the nominal10th July result, 2013 and noid operations, and the KEK computer group and the NII for valuable computing and Super-SINET network sup- 60 port. We acknowledge support from MEXT and JSPS 150 (a) B0 → η′K0 q=+1 (b) B0 →φK0 q=+1 q=−1 4 Inclusiveq=−1 cross-section(Japan); ARC and DEST (Australia); NSFC and KIP of 10 ATLAS 1.5 < |y | < 2 J/s 100 40 3 CMS 1.6 < |y | < 2.4 10 J/sCAS (China); DST (India); MOEHRD, KOSEF, and KRF Spin-alignment envelope 20 2 50 dy [nb/GeV] 10 (Korea); KBN (Poland); MIST (Russia); ARRS (Slovenia); T 10 /dp Entries / 1.5 ps Entries / 2.5 ps SNSF (Switzerland); NSC and MOE (Taiwan); and DOE 0 0m 2 1 )d 0.5 0.5- (U.S.A.). µ -1 + 10 µ ATLAS 0 0 -2 A 10 s= 7 TeV s -0.5 -0.5 -3 L dt = 2.2 pb-1 Asymmetry Asymmetry 10 0 -7.5 -5 -2.5 0 2.5 5 7.5 -7.5Br(J/ 1 -5 -2.52 03 2.54 5 6 57 7.510 20 30 -ξ ∆t(ps) -ξ ∆t(ps) pJ/s [GeV] f f T 40 (c) B0 K0K0K0 q=+1 (d) B0 J/ K0 q=+1 → S S S q=−1 400 → ψ q=−1 [1] Y. Grossman and M. P. Worah, Phys. Lett. B 395, 241 Bruce30 Yabsley (Sydney) 300 Heavy flavour physics (1997);CoEPP/Cairns D. London 2013/07/10 and A. Soni, 1 Phys. / 24 Lett. B 407, 61 20 200 (1997); T. Moroi, Phys. Lett. B 493, 366 (2000); D. 10 100 Chang, A. Masiero, and H. Murayama, Phys. Rev. D 67, Entries / 2.5ps Entries / 0 Entries / 0.5 ps 0 075013 (2003); S. Baek, T. Goto, Y. Okada, and K. 0.5 0.5 Okumura, Phys. Rev. D 64, 095001 (2001). 0 0 [2] A. B. Carter and A. I. Sanda, Phys. Rev. D 23, 1567 -0.5 -0.5 (1981); I. I. Bigi and A. I. Sanda, Nucl. Phys. B193, 85 Asymmetry Asymmetry -7.5 -5 -2.5 0 2.5 5 7.5 -7.5 -5 -2.5 0 2.5 5 7.5 (1981). ∆t(ps) -ξf∆t(ps) [3] M. Kobayashi and T. Maskawa, Prog. Theor. Phys. 49, 652 (1973). FIG. 3 (color online). Background-subtracted t distributions [4] N. Cabibbo, Phys. Rev. Lett. 10, 531 (1963). and asymmetries for events with good tags (r>0:5) for [5] Another naming convention 1 is also used in 0 0 0 0 0 0 0 0 (a) B 0K , (b) B K , (c) B KSKSKS, and literatures. (d) B0 !J= K0. In the asymmetry! plots, solid! curves show [6] M. Beneke and M. Neubert, Nucl. Phys. B675, 333 the fit results;! dashed curves show the SM expectation from our (2003); M. Beneke, Phys. Lett. B 620, 143 (2005); H.-Y. B0 J= K0 measurement. Cheng, C.-K. Chua, and A. Soni, Phys. Rev. D 72, 014006 ! 031802-5 Outline 1 What we mean by \heavy flavour” 2 Open flavour states 3 Hidden flavour states 4 Facilities for heavy flavour studies 5 Summary Bruce Yabsley (Sydney) Heavy flavour physics CoEPP/Cairns 2013/07/10 2 / 24 heavy flavour What we mean by \heavy flavour” the term is somewhat flexible in practice my working definition: \a fermion with mass greater than the hadronic scale is involved . " the original extra flavour, strangeness, doesn't count the strange quark is not quite heavy enough but there are some common features (cf. φ, K∗,...) charm does count, but is more complicated than you think beauty is the ideal case, and has a rich phenomenology top is different again: decays too quickly to hadronise in this talk, I will leave out τ, which does not form bound states, although there are common features with b and c so we should add another clause: \. and is at least potentially part of a bound state" Bruce Yabsley (Sydney) Heavy flavour physics CoEPP/Cairns 2013/07/10 3 / 24 open flavour Open flavour states 1 What we mean by \heavy flavour” 2 Open flavour states Heavy quark symmetry Lifetimes of heavy hadrons Heavy flavour decays Loops and all that 3 Hidden flavour states 4 Facilities for heavy flavour studies 5 Summary Bruce Yabsley (Sydney) Heavy flavour physics CoEPP/Cairns 2013/07/10 4 / 24 heavy hadron the solar system ∼ heavy quark the sun, as a fixed centre of the strong force ∼ light degrees of freedom don't matter: just need a colour 3 HQS: m , universal behaviour; heavy ~s and light ~j decouple; Q ! 1 Q q predictive | narrow and broad states, nontrivial ~L of decays, . open flavour HQ sym Heavy quark symmetry D+ 1869:6 MeV B+ 5279:3 MeV D0 1864:9 MeV B0 5279:6 MeV + 0 Ds 1968:5 MeV Bs 5366:8 MeV + 0 Λc 2286:5 MeV Λb 5619:4 MeV 0 0 Ξc 2470:9 MeV Ξb 5788 MeV + Ξc 2467:8 MeV Ξb− 5791 MeV 0 Ωc 2695 MeV Ωb− 6071 MeV Heavy hadrons are dominated by their heavy quark. The na¨ıvepicture: Bruce Yabsley (Sydney) Heavy flavour physics CoEPP/Cairns 2013/07/10 5 / 24 heavy quark the sun, as a fixed centre of the strong force ∼ light degrees of freedom don't matter: just need a colour 3 HQS: m , universal behaviour; heavy ~s and light ~j decouple; Q ! 1 Q q predictive | narrow and broad states, nontrivial ~L of decays, . open flavour HQ sym Heavy quark symmetry D+ 1869:6 MeV B+ 5279:3 MeV D0 1864:9 MeV B0 5279:6 MeV + 0 Ds 1968:5 MeV Bs 5366:8 MeV + 0 Λc 2286:5 MeV Λb 5619:4 MeV 0 0 Ξc 2470:9 MeV Ξb 5788 MeV + Ξc 2467:8 MeV Ξb− 5791 MeV 0 Ωc 2695 MeV Ωb− 6071 MeV Heavy hadrons are dominated by their heavy quark. The na¨ıvepicture: heavy hadron the solar system ∼ Bruce Yabsley (Sydney) Heavy flavour physics CoEPP/Cairns 2013/07/10 5 / 24 light degrees of freedom don't matter: just need a colour 3 HQS: m , universal behaviour; heavy ~s and light ~j decouple; Q ! 1 Q q predictive | narrow and broad states, nontrivial ~L of decays, .
Load more

Recommended publications
  • The Role of Strangeness in Ultrarelativistic Nuclear
    HUTFT THE ROLE OF STRANGENESS IN a ULTRARELATIVISTIC NUCLEAR COLLISIONS Josef Sollfrank Research Institute for Theoretical Physics PO Box FIN University of Helsinki Finland and Ulrich Heinz Institut f ur Theoretische Physik Universitat Regensburg D Regensburg Germany ABSTRACT We review the progress in understanding the strange particle yields in nuclear colli sions and their role in signalling quarkgluon plasma formation We rep ort on new insights into the formation mechanisms of strange particles during ultrarelativistic heavyion collisions and discuss interesting new details of the strangeness phase di agram In the main part of the review we show how the measured multistrange particle abundances can b e used as a testing ground for chemical equilibration in nuclear collisions and how the results of such an analysis lead to imp ortant con straints on the collision dynamics and spacetime evolution of high energy heavyion reactions a To b e published in QuarkGluon Plasma RC Hwa Eds World Scientic Contents Introduction Strangeness Pro duction Mechanisms QuarkGluon Pro duction Mechanisms Hadronic Pro duction Mechanisms Thermal Mo dels Thermal Parameters Relative and Absolute Chemical Equilibrium The Partition Function The Phase Diagram of Strange Matter The Strange Matter Iglo o Isentropic Expansion Trajectories The T ! Limit of the Phase Diagram
    [Show full text]
  • Particle Physics Dr Victoria Martin, Spring Semester 2012 Lecture 12: Hadron Decays
    Particle Physics Dr Victoria Martin, Spring Semester 2012 Lecture 12: Hadron Decays !Resonances !Heavy Meson and Baryons !Decays and Quantum numbers !CKM matrix 1 Announcements •No lecture on Friday. •Remaining lectures: •Tuesday 13 March •Friday 16 March •Tuesday 20 March •Friday 23 March •Tuesday 27 March •Friday 30 March •Tuesday 3 April •Remaining Tutorials: •Monday 26 March •Monday 2 April 2 From Friday: Mesons and Baryons Summary • Quarks are confined to colourless bound states, collectively known as hadrons: " mesons: quark and anti-quark. Bosons (s=0, 1) with a symmetric colour wavefunction. " baryons: three quarks. Fermions (s=1/2, 3/2) with antisymmetric colour wavefunction. " anti-baryons: three anti-quarks. • Lightest mesons & baryons described by isospin (I, I3), strangeness (S) and hypercharge Y " isospin I=! for u and d quarks; (isospin combined as for spin) " I3=+! (isospin up) for up quarks; I3="! (isospin down) for down quarks " S=+1 for strange quarks (additive quantum number) " hypercharge Y = S + B • Hadrons display SU(3) flavour symmetry between u d and s quarks. Used to predict the allowed meson and baryon states. • As baryons are fermions, the overall wavefunction must be anti-symmetric. The wavefunction is product of colour, flavour, spin and spatial parts: ! = "c "f "S "L an odd number of these must be anti-symmetric. • consequences: no uuu, ddd or sss baryons with total spin J=# (S=#, L=0) • Residual strong force interactions between colourless hadrons propagated by mesons. 3 Resonances • Hadrons which decay due to the strong force have very short lifetime # ~ 10"24 s • Evidence for the existence of these states are resonances in the experimental data Γ2/4 σ = σ • Shape is Breit-Wigner distribution: max (E M)2 + Γ2/4 14 41.
    [Show full text]
  • On the Kaon' S Structure Function from the Strangeness Asymmetry in The
    On the Kaon’ s structure function from the strangeness asymmetry in the nucleon Luis A. Trevisan*, C. Mirez†, Lauro Tomio† and Tobias Frederico** *Departamento de Matemática e Estatística, Universidade Estadual de Ponta Grossa, 84010-790, Ponta Grossa, PR, Brazil † Institute de Física Tedrica, Universidade Estadual Paulista, UNESP, 01405-900, São Paulo, SP, Brazil **Departamento de Física, Instituto Tecnológico de Aeronáutica, CTA, 12228-900, São José dos Campos, SP, Brazil Abstract. We propose a phenomenological approach based in the meson cloud model to obtain the strange quark structure function inside a kaon, considering the strange quark asymmetry inside the nucleon. Keywords: Kaon, strange quark, structure function, asymmetry PACS: 13.75.Jz, 11.30.Hv, 12.39.x, 14.65.Bt The experimental data from CCFR and NuTeV collaborations [1] show that the distri­ bution function for strange and anti-strange quark are asymmetric. If we consider only gluon splitting processes, such asymmetry cannot be found, since the quarks generated by gluons should have the same momentum distribution. So, among the models that have been proposed (or considered) to explain the asymmetry, the most popular are based on meson clouds or A - K fluctuations [2, 3]. By using this kind of model, we analyze the behavior of some parameterizations for the strange quark distribution s(x), in terms of the Bjorken scale x, and discuss how to estimate the structure function for a constituent quark in a Kaon. The strange quark distribution in the nucleon sea, as well as the distribution for u and d quarks, can be separated into perturbative and nonperturbative parts.
    [Show full text]
  • The Results and Their Interpretation
    178 Part C the postulate of quarks as the fundamental building blocks The results and their of matter. interpretation Strangeness, parity violation, and charm Chapter 16 The decays of the strange particles, in particular of the kaons, paved the way for the further development of our The CKM matrix and the understanding. Before 1954, the three discrete symmetries Kobayashi-Maskawa mechanism C (charge conjugation), P (parity) and T (time rever- sal) were believed to be conserved individually, a conclu- Editors: sion drawn from the well known electromagnetic interac- Adrian Bevan and Soeren Prell (BABAR) tion. Based on this assumption, the so called θ-τ puzzle Boˇstjan Golob and Bruce Yabsley (Belle) emerged: Two particles (at that time called θ and τ, where Thomas Mannel (theory) the latter is not to be confused with the third generation lepton) were observed, which had identical masses and lifetimes. However, they obviously had different parities, since the θ particle decayed into two pions (a state with 16.1 Historical background even parity), and the τ particle decays into three pions (a state with odd parity). Fundamentals The resolution was provided by the bold assumption by Lee and Yang (1956) that parity is not conserved in In the early twentieth century the “elementary” particles weak interactions, and θ and τ are in fact the same par- known were the proton, the electron and the photon. The ticle, which we now call the charged kaon. Subsequently first extension of this set of particles occurred with the the parity violating V A structure of the weak interac- neutrino hypothesis, first formulated by W.
    [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]
  • PHY401 - Nuclear and Particle Physics
    PHY401 - Nuclear and Particle Physics Monsoon Semester 2020 Dr. Anosh Joseph, IISER Mohali LECTURE 27 Wednesday, October 28, 2020 (Note: This is an online lecture due to COVID-19 interruption.) Contents 1 CP Violation 1 1.1 CP Eigenstates of Neutral Kaons . .5 1.2 Strangeness Oscillations . .5 2 Formulation of the Standard Model 6 2.1 Quarks and Leptons . .7 2.2 Quark Content of Mesons . .8 2.3 Quark Content of Baryons . 10 1 CP Violation In 1956 Wu and collaborators conducted an experiment to look for P violation in cobalt-60 decays. The presence of P violation in this system suggested that there is something unique about the weak force. If P and C can be violated individually, how about the combination of the two? CP takes a physical particle state to a physical anti-particle state. Thus, invariance under CP is equivalent to having a particle-anti-particle symmetry in nature. However, the universe is known to be dominated by matter, with essentially no antimatter present. That is, there is a definite particle-anti-particle asymmetry in the universe. CP may not be a symmetry of all fundamental interactions. There are in fact processes in which CP is violated. CP violation implies that there are microscopic (sub-atomic) processes in which time has a unique direction of flow. PHY401 - Nuclear and Particle Physics Monsoon Semester 2020 In 1964, James Cronin and Val Fitch tested CP violations in neutral kaons. Neutral kaons can be represented as jK0i = jsd¯ i; jK¯ 0i = jsd¯i: (1) K¯ 0 is the anti-particle of K0.
    [Show full text]
  • Introduction to Elementary Particle Physics
    Introduction to Elementary Particle Physics Néda Sadooghi Department of Physics Sharif University of Technology Tehran - Iran Elementary Particle Physics Lecture 9 and 10: Esfand 18 and 20, 1397 1397-98-II Leptons and quarks Lectrue 9 Leptons Lectrue 9 Remarks: I Lepton flavor number conservation: - Lepton flavor number of leptons Le; Lµ; Lτ = +1 - Lepton flavor number of antileptons Le; Lµ; Lτ = −1 Assumption: No neutrino mixing + + − + + Ex.: π ! µ + νµ; n ! p + e +ν ¯e; µ ! e + νe +ν ¯µ But, µ+ ! e+ + γ is forbidden I Two other quantum numbers for leptons - Weak hypercharge YW : It is 1 for all left-handed leptons - Weak isospin T3: ( ) ( ) e− − 1 ! 2 For each lepton generation, for example T3 = 1 νe + 2 I Type of interaction: - Charged leptons undergo both EM and weak interactions - Neutrinos interact only weakly Lectrue 9 Quarks Lectrue 9 Remarks I Hadrons are bound states of constituent (valence) quarks I Bare (current) quarks are not dressed. We denote the current quark mass by m0 I Dressed quarks are surrounded by a cloud of virtual quarks and gluons (Sea quarks) I This cloud explains the large constituent-quark mass M I For hadrons the constituent quark mass M = the binding energy required to make the hadrons spontaneously emit a meson containing the valence quark For light quarks (u,d,s): m0 ≪ M For heavy quarks (c,b,t): m0 ' M Lectrue 9 Remarks: I Type of interaction: - All quarks undergo EM and strong interactions I Mean lifetime (typical time of interaction): In general, - Particles which mainly decay through strong interactions have a mean lifetime of about 10−23 sec - Particles which mainly decay through electromagnetic interactions, signaled by the production of photons, have a mean lifetime in the range of 10−20 − 10−16 sec - Particles that decay through weak forces have a mean lifetime in the range of 10−10 − 10−8 sec Lectrue 9 Other quantum numbers (see Perkins Chapter 4) Flavor Baryon Spin Isospin Charm Strangeness Topness Bottomness El.
    [Show full text]
  • The Quark Model and Deep Inelastic Scattering
    The quark model and deep inelastic scattering Contents 1 Introduction 2 1.1 Pions . 2 1.2 Baryon number conservation . 3 1.3 Delta baryons . 3 2 Linear Accelerators 4 3 Symmetries 5 3.1 Baryons . 5 3.2 Mesons . 6 3.3 Quark flow diagrams . 7 3.4 Strangeness . 8 3.5 Pseudoscalar octet . 9 3.6 Baryon octet . 9 4 Colour 10 5 Heavier quarks 13 6 Charmonium 14 7 Hadron decays 16 Appendices 18 .A Isospin x 18 .B Discovery of the Omega x 19 1 The quark model and deep inelastic scattering 1 Symmetry, patterns and substructure The proton and the neutron have rather similar masses. They are distinguished from 2 one another by at least their different electromagnetic interactions, since the proton mp = 938:3 MeV=c is charged, while the neutron is electrically neutral, but they have identical properties 2 mn = 939:6 MeV=c under the strong interaction. This provokes the question as to whether the proton and neutron might have some sort of common substructure. The substructure hypothesis can be investigated by searching for other similar patterns of multiplets of particles. There exists a zoo of other strongly-interacting particles. Exotic particles are ob- served coming from the upper atmosphere in cosmic rays. They can also be created in the labortatory, provided that we can create beams of sufficient energy. The Quark Model allows us to apply a classification to those many strongly interacting states, and to understand the constituents from which they are made. 1.1 Pions The lightest strongly interacting particles are the pions (π).
    [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]
  • Invariance Principles
    Invariance Principles • Invariance of states under operations implies conservation laws – Invariance of energy under space translation → momentum conservation – Invariance of energy under space rotation → angular momentum conservation • Continuous Space-Time Transformations – Translations – Rotations – Extension of Poincare group to include fermionic anticommuting spinors (SUSY) • Discrete Transformations – Space Time Inversion (Parity=P) – Particle-Antiparticle Interchange (Charge Conjugation=C) – Time Reversal (T) – Combinations of these: CP, CPT • Continuous Transformations of Internal Symmetries – Isospin – SU(3)flavor – SU(3)color – Weak Isospin – These are all gauge symmetries Symmetries and Conservation Laws SU(2) SU(3) 8 generators; 2 can be diagonalized at the same time: rd I3 … 3 component of isospin Y … hypercharge SU(3) Raising and lowering operators Y = +1/2√3 Y = +1/√3 SU(3) SU(3) Adding 2 quarks SU(3) Adding 3 quarks Quantum Numbers • Electric Charge • Baryon Number • Lepton Number • Strangeness • Spin • Isospin • Parity • Charge Conjugation Electric Charge Quantum Numbers are quantised properties of particles that are subject to constraints. They are often related to symmetries Electric Charge Q is conserved in all interactions Strong ✔ Interaction Weak ✔ Interaction Baryon Number Baryon number is the net number of baryons or the net number of quarks ÷ 3 Baryons have B = +1 Quarks have B = +⅓ Antibaryons have B = -1 or Antiquarks have B = -⅓ Everything else has B = 0 Everything else has B = 0 Baryons = qqq = ⅓ + ⅓ + ⅓
    [Show full text]
  • Particle Properties
    Particle Properties You don’t have to remember this information! In an exam the masses of the particles are given on the constant sheet. Any other required information will be given to you. What you should know, or be able to work out, is: • the quantum numbers, and if they are conserved are or not • the force responsible for a decay, from the lifetime • the main decay modes, using a Feynman diagram • that the +, − and 0 superscripts correspond to the electric charge of the particles • the relationship between a particle and its antiparticle. Anti-particles are not named in the tables. Anti-particles have the same mass, same lifetime, opposite quantum numbers from the particle. Anti-particles decay into the anti-particles of the shown modes. For example, an anti-muon, µ+, has a mass of 2 −6 105.7 MeV/c and a lifetime of 2.197 × 10 s. Its quantum numbers are Le = 0,Lµ = + + −1,Lτ = 0 and Q = +1. Its main decay mode is µ → e νeν¯µ. Quantum Numbers The following quantum numbers are conserved in all reactions: • Total quark number, Nq = N(q) − N(¯q). – Nq = +1 for all quarks – Nq = −1 for all anti-quarks – Nq = 0 for all leptons and anti-leptons – Nq = 3 for baryons and Nq = 0 for mesons. • The three lepton flavour quantum numbers: − + – Electron Number: Le = N(e ) − N(e ) + N(νe) − N(¯νe) − + – Muon Number: Lµ = N(µ ) − N(µ ) + N(νµ) − N(¯νµ) − + – Tau Number: Lτ = N(τ ) − N(τ ) + N(ντ ) − N(¯ντ ) • Electric charge, Q.
    [Show full text]
  • Strange Quarks in Nuclei
    -'i-'-.- •//(:•', BROOKHAVEN NATIONAL LABORATORY BNL--46322 June 1991 DE91 015833 STRANGE QUARKS IN NUCLEI Carl B. Dover Physics Department Brookhaven National Laboratory Upton, New York 11973 ABSTRACT We survey the field of strange particle nuclear physics, starting with the spectroscopy of strangeness S = — 1 A hypernuclei, proceeding to an inter- pretation of recent data on 5 = —2 AA hypernuclear production and decay, and finishing with some speculations on the production of multi-strange nuclear composites (hypernuclei or "strangelets") in relativistic heavy ion collisions. Invited talk presented at the Intersections between Particle and Nuclear Physics Tucson, Arizona May 24-29, 1991 This manuscript has been authored under contract number DE-AC02-76CII00016 with the U.S. Depart- ment of Energy. Accordingly, the U.S. Government retains a non-exclusive, royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for U.S. Government purposes. DBTRBUTION OF TH,S OOCUMBlf » STRANGE QUARKS IN NUCLEI Carl B. DOVER Brookhaven National Laboratory, Upton, New York 11973, USA ABSTRACT We survey the field of strange particle nuclear physics, starting with the spec- troscopy of strangeness 5 = — 1 A hypernuclei, proceeding to an interpretation of recent data on S = — 2 A A hypernuclear production and decay, and finishing with some speculations on the production of multi-strange nuclear composites (hypernuclei or "strangelets") in relativistic heavy ion collisions. 1. INTRODUCTION In this talk, we explore the strangeness (S) degree of freedom in nuclei. We start with a discussion of S = —1 hypernuclei, which consist of a single hy- peron (A or S) embedded in the nuclear medium.
    [Show full text]