Particle Physics Dr Victoria Martin, Spring Semester 2012 Lecture 11: Mesons and Baryons
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The Five Common Particles
The Five Common Particles The world around you consists of only three particles: protons, neutrons, and electrons. Protons and neutrons form the nuclei of atoms, and electrons glue everything together and create chemicals and materials. Along with the photon and the neutrino, these particles are essentially the only ones that exist in our solar system, because all the other subatomic particles have half-lives of typically 10-9 second or less, and vanish almost the instant they are created by nuclear reactions in the Sun, etc. Particles interact via the four fundamental forces of nature. Some basic properties of these forces are summarized below. (Other aspects of the fundamental forces are also discussed in the Summary of Particle Physics document on this web site.) Force Range Common Particles It Affects Conserved Quantity gravity infinite neutron, proton, electron, neutrino, photon mass-energy electromagnetic infinite proton, electron, photon charge -14 strong nuclear force ≈ 10 m neutron, proton baryon number -15 weak nuclear force ≈ 10 m neutron, proton, electron, neutrino lepton number Every particle in nature has specific values of all four of the conserved quantities associated with each force. The values for the five common particles are: Particle Rest Mass1 Charge2 Baryon # Lepton # proton 938.3 MeV/c2 +1 e +1 0 neutron 939.6 MeV/c2 0 +1 0 electron 0.511 MeV/c2 -1 e 0 +1 neutrino ≈ 1 eV/c2 0 0 +1 photon 0 eV/c2 0 0 0 1) MeV = mega-electron-volt = 106 eV. It is customary in particle physics to measure the mass of a particle in terms of how much energy it would represent if it were converted via E = mc2. -
Fundamentals of Particle Physics
Fundamentals of Par0cle Physics Particle Physics Masterclass Emmanuel Olaiya 1 The Universe u The universe is 15 billion years old u Around 150 billion galaxies (150,000,000,000) u Each galaxy has around 300 billion stars (300,000,000,000) u 150 billion x 300 billion stars (that is a lot of stars!) u That is a huge amount of material u That is an unimaginable amount of particles u How do we even begin to understand all of matter? 2 How many elementary particles does it take to describe the matter around us? 3 We can describe the material around us using just 3 particles . 3 Matter Particles +2/3 U Point like elementary particles that protons and neutrons are made from. Quarks Hence we can construct all nuclei using these two particles -1/3 d -1 Electrons orbit the nuclei and are help to e form molecules. These are also point like elementary particles Leptons We can build the world around us with these 3 particles. But how do they interact. To understand their interactions we have to introduce forces! Force carriers g1 g2 g3 g4 g5 g6 g7 g8 The gluon, of which there are 8 is the force carrier for nuclear forces Consider 2 forces: nuclear forces, and electromagnetism The photon, ie light is the force carrier when experiencing forces such and electricity and magnetism γ SOME FAMILAR THE ATOM PARTICLES ≈10-10m electron (-) 0.511 MeV A Fundamental (“pointlike”) Particle THE NUCLEUS proton (+) 938.3 MeV neutron (0) 939.6 MeV E=mc2. Einstein’s equation tells us mass and energy are equivalent Wave/Particle Duality (Quantum Mechanics) Einstein E -
Jet Quenching in Quark Gluon Plasma: flavor Tomography at RHIC and LHC by the CUJET Model
Jet quenching in Quark Gluon Plasma: flavor tomography at RHIC and LHC by the CUJET model Alessandro Buzzatti Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Graduate School of Arts and Sciences Columbia University 2013 c 2013 Alessandro Buzzatti All Rights Reserved Abstract Jet quenching in Quark Gluon Plasma: flavor tomography at RHIC and LHC by the CUJET model Alessandro Buzzatti A new jet tomographic model and numerical code, CUJET, is developed in this thesis and applied to the phenomenological study of the Quark Gluon Plasma produced in Heavy Ion Collisions. Contents List of Figures iv Acknowledgments xxvii Dedication xxviii Outline 1 1 Introduction 4 1.1 Quantum ChromoDynamics . .4 1.1.1 History . .4 1.1.2 Asymptotic freedom and confinement . .7 1.1.3 Screening mass . 10 1.1.4 Bag model . 12 1.1.5 Chiral symmetry breaking . 15 1.1.6 Lattice QCD . 19 1.1.7 Phase diagram . 28 1.2 Quark Gluon Plasma . 30 i 1.2.1 Initial conditions . 32 1.2.2 Thermalized plasma . 36 1.2.3 Finite temperature QFT . 38 1.2.4 Hydrodynamics and collective flow . 45 1.2.5 Hadronization and freeze-out . 50 1.3 Hard probes . 55 1.3.1 Nuclear effects . 57 2 Energy loss 62 2.1 Radiative energy loss models . 63 2.2 Gunion-Bertsch incoherent radiation . 67 2.3 Opacity order expansion . 69 2.3.1 Gyulassy-Wang model . 70 2.3.2 GLV . 74 2.3.3 Multiple gluon emission . 78 2.3.4 Multiple soft scattering . -
Introduction to Particle Physics
SFB 676 – Projekt B2 Introduction to Particle Physics Christian Sander (Universität Hamburg) DESY Summer Student Lectures – Hamburg – 20th July '11 Outline ● Introduction ● History: From Democrit to Thomson ● The Standard Model ● Gauge Invariance ● The Higgs Mechanism ● Symmetries … Break ● Shortcomings of the Standard Model ● Physics Beyond the Standard Model ● Recent Results from the LHC ● Outlook Disclaimer: Very personal selection of topics and for sure many important things are left out! 20th July '11 Introduction to Particle Physics 2 20th July '11 Introduction to Particle PhysicsX Files: Season 2, Episode 233 … für Chester war das nur ein Weg das Geld für das eigentlich theoretische Zeugs aufzubringen, was ihn interessierte … die Erforschung Dunkler Materie, …ähm… Quantenpartikel, Neutrinos, Gluonen, Mesonen und Quarks. Subatomare Teilchen Die Geheimnisse des Universums! Theoretisch gesehen sind sie sogar die Bausteine der Wirklichkeit ! Aber niemand weiß, ob sie wirklich existieren !? 20th July '11 Introduction to Particle PhysicsX Files: Season 2, Episode 234 The First Particle Physicist? By convention ['nomos'] sweet is sweet, bitter is bitter, hot is hot, cold is cold, color is color; but in truth there are only atoms and the void. Democrit, * ~460 BC, †~360 BC in Abdera Hypothesis: ● Atoms have same constituents ● Atoms different in shape (assumption: geometrical shapes) ● Iron atoms are solid and strong with hooks that lock them into a solid ● Water atoms are smooth and slippery ● Salt atoms, because of their taste, are sharp and pointed ● Air atoms are light and whirling, pervading all other materials 20th July '11 Introduction to Particle Physics 5 Corpuscular Theory of Light Light consist out of particles (Newton et al.) ↕ Light is a wave (Huygens et al.) ● Mainly because of Newtons prestige, the corpuscle theory was widely accepted (more than 100 years) Sir Isaac Newton ● Failing to describe interference, diffraction, and *1643, †1727 polarization (e.g. -
Quantum Field Theory*
Quantum Field Theory y Frank Wilczek Institute for Advanced Study, School of Natural Science, Olden Lane, Princeton, NJ 08540 I discuss the general principles underlying quantum eld theory, and attempt to identify its most profound consequences. The deep est of these consequences result from the in nite number of degrees of freedom invoked to implement lo cality.Imention a few of its most striking successes, b oth achieved and prosp ective. Possible limitation s of quantum eld theory are viewed in the light of its history. I. SURVEY Quantum eld theory is the framework in which the regnant theories of the electroweak and strong interactions, which together form the Standard Mo del, are formulated. Quantum electro dynamics (QED), b esides providing a com- plete foundation for atomic physics and chemistry, has supp orted calculations of physical quantities with unparalleled precision. The exp erimentally measured value of the magnetic dip ole moment of the muon, 11 (g 2) = 233 184 600 (1680) 10 ; (1) exp: for example, should b e compared with the theoretical prediction 11 (g 2) = 233 183 478 (308) 10 : (2) theor: In quantum chromo dynamics (QCD) we cannot, for the forseeable future, aspire to to comparable accuracy.Yet QCD provides di erent, and at least equally impressive, evidence for the validity of the basic principles of quantum eld theory. Indeed, b ecause in QCD the interactions are stronger, QCD manifests a wider variety of phenomena characteristic of quantum eld theory. These include esp ecially running of the e ective coupling with distance or energy scale and the phenomenon of con nement. -
Differences Between Quark and Gluon Jets As Seen at LEP 1 Introduction
UA0501305 Differences between Quark and Gluon jets as seen at LEP Marek Tasevsky CERN, CH-1211 Geneva 28, Switzerland E-mail: [email protected] Abstract The differences between quark and gluon jets are stud- ied using LEP results on jet widths, scale dependent multi- plicities, ratios of multiplicities, slopes and curvatures and fragmentation functions. It is emphasized that the ob- served differences stem primarily from the different quark and gluon colour factors. 1 Introduction The physics of the differences between quark and gluonjets contin- uously attracts an interest of both, theorists and experimentalists. Hadron production can be described by parton showers (successive gluon emissions and splittings) followed by formation of hadrons which cannot be described perturbatively. The gluon emission, being dominant process in the parton showers, is proportional to the colour factor associated with the coupling of the emitted gluon to the emitter. These colour factors are CA = 3 when the emit- ter is a gluon and Cp = 4/3 when it is a quark. Consequently, U6 the multiplicity from a gluon source is (asymptotically) 9/4 higher than from a quark source. In QCD calculations, the jet properties are usually defined in- clusively, by the particles in hemispheres of quark-antiquark (qq) or gluon-gluon (gg) systems in an overall colour singlet rather than by a jet algorithm. In contrast to the experimental results which often depend on a jet finder employed (biased jets), the inclusive jets do not depend on any jet finder (unbiased jets). 2 Results 2.1 Jet Widths As a consequence of the greater radiation of soft gluons in a gluon jet compared to a quark jet, gluon jets are predicted to be broader. -
Introduction to QCD and Jet I
Introduction to QCD and Jet I Bo-Wen Xiao Pennsylvania State University and Institute of Particle Physics, Central China Normal University Jet Summer School McGill June 2012 1 / 38 Overview of the Lectures Lecture 1 - Introduction to QCD and Jet QCD basics Sterman-Weinberg Jet in e+e− annihilation Collinear Factorization and DGLAP equation Basic ideas of kt factorization Lecture 2 - kt factorization and Dijet Processes in pA collisions kt Factorization and BFKL equation Non-linear small-x evolution equations. Dijet processes in pA collisions (RHIC and LHC related physics) Lecture 3 - kt factorization and Higher Order Calculations in pA collisions No much specific exercise. 1. filling gaps of derivation; 2. Reading materials. 2 / 38 Outline 1 Introduction to QCD and Jet QCD Basics Sterman-Weinberg Jets Collinear Factorization and DGLAP equation Transverse Momentum Dependent (TMD or kt) Factorization 3 / 38 References: R.D. Field, Applications of perturbative QCD A lot of detailed examples. R. K. Ellis, W. J. Stirling and B. R. Webber, QCD and Collider Physics CTEQ, Handbook of Perturbative QCD CTEQ website. John Collins, The Foundation of Perturbative QCD Includes a lot new development. Yu. L. Dokshitzer, V. A. Khoze, A. H. Mueller and S. I. Troyan, Basics of Perturbative QCD More advanced discussion on the small-x physics. S. Donnachie, G. Dosch, P. Landshoff and O. Nachtmann, Pomeron Physics and QCD V. Barone and E. Predazzi, High-Energy Particle Diffraction 4 / 38 Introduction to QCD and Jet QCD Basics QCD QCD Lagrangian a a a b c with F = @µA @ν A gfabcA A . µν ν − µ − µ ν Non-Abelian gauge field theory. -
A Young Physicist's Guide to the Higgs Boson
A Young Physicist’s Guide to the Higgs Boson Tel Aviv University Future Scientists – CERN Tour Presented by Stephen Sekula Associate Professor of Experimental Particle Physics SMU, Dallas, TX Programme ● You have a problem in your theory: (why do you need the Higgs Particle?) ● How to Make a Higgs Particle (One-at-a-Time) ● How to See a Higgs Particle (Without fooling yourself too much) ● A View from the Shadows: What are the New Questions? (An Epilogue) Stephen J. Sekula - SMU 2/44 You Have a Problem in Your Theory Credit for the ideas/example in this section goes to Prof. Daniel Stolarski (Carleton University) The Usual Explanation Usual Statement: “You need the Higgs Particle to explain mass.” 2 F=ma F=G m1 m2 /r Most of the mass of matter lies in the nucleus of the atom, and most of the mass of the nucleus arises from “binding energy” - the strength of the force that holds particles together to form nuclei imparts mass-energy to the nucleus (ala E = mc2). Corrected Statement: “You need the Higgs Particle to explain fundamental mass.” (e.g. the electron’s mass) E2=m2 c4+ p2 c2→( p=0)→ E=mc2 Stephen J. Sekula - SMU 4/44 Yes, the Higgs is important for mass, but let’s try this... ● No doubt, the Higgs particle plays a role in fundamental mass (I will come back to this point) ● But, as students who’ve been exposed to introductory physics (mechanics, electricity and magnetism) and some modern physics topics (quantum mechanics and special relativity) you are more familiar with.. -
On Particle Physics
On Particle Physics Searching for the Fundamental US ATLAS The continuing search for the basic building blocks of matter is the US ATLAS subject of Particle Physics (also called High Energy Physics). The idea of fundamental building blocks has evolved from the concept of four elements (earth, air, fire and water) of the Ancient Greeks to the nineteenth century picture of atoms as tiny “billiard balls.” The key word here is FUNDAMENTAL — objects which are simple and have no structure — they are not made of anything smaller! Our current understanding of these fundamental constituents began to fall into place around 100 years ago, when experimenters first discovered that the atom was not fundamental at all, but was itself made of smaller building blocks. Using particle probes as “microscopes,” scientists deter- mined that an atom has a dense center, or NUCLEUS, of positive charge surrounded by a dilute “cloud” of light, negatively- charged electrons. In between the nucleus and electrons, most of the atom is empty space! As the particle “microscopes” became more and more powerful, scientists found that the nucleus was composed of two types of yet smaller constituents called protons and neutrons, and that even pro- tons and neutrons are made up of smaller particles called quarks. The quarks inside the nucleus come in two varieties, called “up” or u-quark and “down” or d-quark. As far as we know, quarks and electrons really are fundamental (although experimenters continue to look for evidence to the con- trary). We know that these fundamental building blocks are small, but just how small are they? Using probes that can “see” down to very small distances inside the atom, physicists know that quarks and electrons are smaller than 10-18 (that’s 0.000 000 000 000 000 001! ) meters across. -
Monte Carlo Methods in Particle Physics Bryan Webber University of Cambridge IMPRS, Munich 19-23 November 2007
Monte Carlo Methods in Particle Physics Bryan Webber University of Cambridge IMPRS, Munich 19-23 November 2007 Monte Carlo Methods 3 Bryan Webber Structure of LHC Events 1. Hard process 2. Parton shower 3. Hadronization 4. Underlying event Monte Carlo Methods 3 Bryan Webber Lecture 3: Hadronization Partons are not physical 1. Phenomenological particles: they cannot models. freely propagate. 2. Confinement. Hadrons are. 3. The string model. 4. Preconfinement. Need a model of partons' 5. The cluster model. confinement into 6. Underlying event hadrons: hadronization. models. Monte Carlo Methods 3 Bryan Webber Phenomenological Models Experimentally, two jets: Flat rapidity plateau and limited Monte Carlo Methods 3 Bryan Webber Estimate of Hadronization Effects Using this model, can estimate hadronization correction to perturbative quantities. Jet energy and momentum: with mean transverse momentum. Estimate from Fermi motion Jet acquires non-perturbative mass: Large: ~ 10 GeV for 100 GeV jets. Monte Carlo Methods 3 Bryan Webber Independent Fragmentation Model (“Feynman—Field”) Direct implementation of the above. Longitudinal momentum distribution = arbitrary fragmentation function: parameterization of data. Transverse momentum distribution = Gaussian. Recursively apply Hook up remaining soft and Strongly frame dependent. No obvious relation with perturbative emission. Not infrared safe. Not a model of confinement. Monte Carlo Methods 3 Bryan Webber Confinement Asymptotic freedom: becomes increasingly QED-like at short distances. QED: + – but at long distances, gluon self-interaction makes field lines attract each other: QCD: linear potential confinement Monte Carlo Methods 3 Bryan Webber Interquark potential Can measure from or from lattice QCD: quarkonia spectra: String tension Monte Carlo Methods 3 Bryan Webber String Model of Mesons Light quarks connected by string. -
Deep Inelastic Scattering
Particle Physics Michaelmas Term 2011 Prof Mark Thomson e– p Handout 6 : Deep Inelastic Scattering Prof. M.A. Thomson Michaelmas 2011 176 e– p Elastic Scattering at Very High q2 ,At high q2 the Rosenbluth expression for elastic scattering becomes •From e– p elastic scattering, the proton magnetic form factor is at high q2 Phys. Rev. Lett. 23 (1969) 935 •Due to the finite proton size, elastic scattering M.Breidenbach et al., at high q2 is unlikely and inelastic reactions where the proton breaks up dominate. e– e– q p X Prof. M.A. Thomson Michaelmas 2011 177 Kinematics of Inelastic Scattering e– •For inelastic scattering the mass of the final state hadronic system is no longer the proton mass, M e– •The final state hadronic system must q contain at least one baryon which implies the final state invariant mass MX > M p X For inelastic scattering introduce four new kinematic variables: ,Define: Bjorken x (Lorentz Invariant) where •Here Note: in many text books W is often used in place of MX Proton intact hence inelastic elastic Prof. M.A. Thomson Michaelmas 2011 178 ,Define: e– (Lorentz Invariant) e– •In the Lab. Frame: q p X So y is the fractional energy loss of the incoming particle •In the C.o.M. Frame (neglecting the electron and proton masses): for ,Finally Define: (Lorentz Invariant) •In the Lab. Frame: is the energy lost by the incoming particle Prof. M.A. Thomson Michaelmas 2011 179 Relationships between Kinematic Variables •Can rewrite the new kinematic variables in terms of the squared centre-of-mass energy, s, for the electron-proton collision e– p Neglect mass of electron •For a fixed centre-of-mass energy, it can then be shown that the four kinematic variables are not independent. -
Fragmentation and Hadronization 1 Introduction
Fragmentation and Hadronization Bryan R. Webber Theory Division, CERN, 1211 Geneva 23, Switzerland, and Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, U.K.1 1 Introduction Hadronic jets are amongst the most striking phenomena in high-energy physics, and their importance is sure to persist as searching for new physics at hadron colliders becomes the main activity in our field. Signatures involving jets almost always have the largest cross sections, but are the most difficult to interpret and to distinguish from background. Insight into the properties of jets is therefore doubly valuable: both as a test of our understanding of strong interaction dy- namics and as a tool for extracting new physics signals in multi-jet channels. In the present talk, I shall concentrate on jet fragmentation and hadroniza- tion, the topic of jet production having been covered admirably elsewhere [1, 2]. The terms fragmentation and hadronization are often used interchangeably, but I shall interpret the former strictly as referring to inclusive hadron spectra, for which factorization ‘theorems’2 are available. These allow predictions to be made without any detailed assumptions concerning hadron formation. A brief review of the relevant theory is given in Section 2. Hadronization, on the other hand, will be taken here to refer specifically to the mechanism by which quarks and gluons produced in hard processes form the hadrons that are observed in the final state. This is an intrinsically non- perturbative process, for which we only have models at present. The main models are reviewed in Section 3. In Section 4 their predictions, together with other less model-dependent expectations, are compared with the latest data on single- particle yields and spectra.