The Ghost Particle 1 Ask Students If They Can Think of Some Things They Cannot Directly See but They Know Exist
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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 -
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. -
Read About the Particle Nature of Matter
READING MATERIAL Read About the Particle Nature of Matter PARTICLES OF MATTER DEFINITION Matter is anything that has weight and takes up space. A particle is the smallest possible unit of matter. Understanding that matter is made of tiny particles too small to be seen can help us understand the behavior and properties of matter. To better understand how the 3 states of matter work…. LET’S BREAK IT DOWN! All matter is made of particles that are too small to be seen. Everything you can see and touch is made of matter. It is all the “stuff” in the universe. Things that are not made of matter include energy, and ideas like peace and love. Matter is made up of small particles that are too small to be seen, even with a powerful microscope. They are so small that you would have to put about 100,000 particles in a line to equal the width of a human hair! Page 1 The arrangement of particles determines the state of matter. Particles are arranged and move differently in each state of matter. Solids contain particles that are tightly packed, with very little space between particles. If an object can hold its own shape and is difficult to compress, it is a solid. Liquids contain particles that are more loosely packed than solids, but still closely packed compared to gases. Particles in liquids are able to slide past each other, or flow, to take the shape of their container. Particles are even more spread apart in gases. Gases will fill any container, but if they are not in a container, they will escape into the air. -
Spin and Parity of the Λ(1405) Baryon
Spin and Parity of the (1405) Baryon here [1], precisely because of the difficulty in producing it, and in particular because it must be produced spin polarized for a measurement to be made. We used photoproduction data from the CLAS detector at Jefferson Lab. The reaction + p K+ + (1405) was analyzed in the decay channel (1405) + + , where the decay distribution to + and the variation of the + polarization with respect to the (1405) polarization direction determined the spin and parity. The (1405) was produced in the c.m. energy range K 2.55 < W < 2.85 GeV and for 0.6 coscm.. 0.9 . The decay angular distribution of the (1405) in its rest Every subatomic particle has a set of properties that frame was found to be isotropic, which means the define its identity. Beyond mass, charge, and magnetic particle is consistent with spin J = ½. The first figure moment, each particle has discrete quantum numbers illustrates how the polarization P of a parent particle that include its spin angular momentum J and its with spin ½, in this case the (1405), transfers intrinsic parity P. The spin comes in integer steps of + starting from ½ for 3-quark objects (baryons). The polarization Q to the daughter baryon, in this case the , depending on whether the decay is in a spatial S wave parity is either positive (“+”) or negative (“”) (L=0) or P wave (L=1). This distinction is what depending on the inversion symmetry of its spatial wave determines the parity of the final state, and hence of the function. For example, the familiar proton and neutron parent. -
The Subatomic Particle Mass Spectrum
The Subatomic Particle Mass Spectrum Robert L. Oldershaw 12 Emily Lane Amherst, MA 01002 USA [email protected] Key Words: Subatomic Particles; Particle Mass Spectrum; General Relativity; Kerr Metric; Discrete Self-Similarity; Discrete Scale Relativity 1 Abstract: Representative members of the subatomic particle mass spectrum in the 100 MeV to 7,000 MeV range are retrodicted to a first approximation using the Kerr solution of General Relativity. The particle masses appear to form a restricted set of quantized values of a Kerr- based angular momentum-mass relation: M = n1/2 M, where values of n are a set of discrete integers and M is a revised Planck mass. A fractal paradigm manifesting global discrete self- similarity is critical to a proper determination of M, which differs from the conventional Planck mass by a factor of roughly 1019. This exceedingly simple and generic mass equation retrodicts the masses of a representative set of 27 well-known particles with an average relative error of 1.6%. A more rigorous mass formula, which includes the total spin angular momentum rule of Quantum Mechanics, the canonical spin values of the particles, and the dimensionless rotational parameter of the Kerr angular momentum-mass relation, is able to retrodict the masses of the 8 dominant baryons in the 900 MeV to 1700 MeV range at the < 99.7% > level. 2 “There remains one especially unsatisfactory feature [of the Standard Model of particle physics]: the observed masses of the particles, m. There is no theory that adequately explains these numbers. We use the numbers in all our theories, but we do not understand them – what they are, or where they come from. -
FUNDAMENTAL PARTICLES Year 14 Physics Erin Hannigan
FUNDAMENTAL PARTICLES Year 14 Physics Erin Hannigan 1 Key Word List ■ Natural Philosophy – the science of matter and energy and their interactions. ■ Hadron – any elementary particle that interacts strongly with other particles. ■ Lepton – an elementary particle that participates in weak interactions. ■ Subatomic Particle – a body having finite mass and internal structure but negligible dimensions. ■ Quark – any of a number f subatomic particles carrying a fractional electric charge, postulated as building blocks of the hadrons. Quarks have not been directly observed but theoretical predictions based on their existence have been confirmed experimentally. ■ Atom – the smallest component of an element having the chemical properties of the element. 2 Fundamental Particles ■ Fundamental particles (also called elementary particles) are the smallest building blocks of the universe. The key characteristic of fundamental particles is that they have no internal structure. ■ There are two type of fundamental particles: – Particles that make up all matter, called fermions – Particles that carry force, called bosons ■ The four fundamental forces include: – Gravity – The weak force – Electromagnetism – The strong force 3 The Four Fundamental Forces ■ The four fundamental forces of nature govern everything that happens in the universe. ■ Gravity – The attraction between two objects that have mass or energy ■ The weak force – Responsible for particle decay – Physicists describe this interaction through the exchange of force-carrying particles called -
Baryon Resonances and Pentaquarks on the Lattice ✩
Nuclear Physics A 754 (2005) 248c–260c Baryon resonances and pentaquarks on the lattice ✩ F.X. Lee a,b,∗, C. Bennhold a a Center for Nuclear Studies, George Washington University, Washington, DC 20052, USA b Jefferson Lab, 12000 Jefferson Avenue, Newport News, VA 23606, USA Received 17 December 2004; accepted 22 December 2004 Available online 21 January 2005 Abstract We review recent progress in computing excited baryons and pentaquarks in lattice QCD. 2004 Elsevier B.V. All rights reserved. 1. QCD primer Quantum Chromodynamics (QCD) is widely accepted as the fundamental theory of the strong interaction. The QCD Lagrangian density can be written down simply in one line (in Euclidean space) 1 L = Tr F F µν +¯q γ µD + m q, (1) QCD 2 µν µ q where Fµν = ∂Aµ − ∂Aν + g[Aµ,Aν] is the gluon field strength tensor and Dµ = ∂µ + gAµ is the covariant derivative which provides the interaction between the gluon and quark terms. The action of QCD is the integral of the Lagrangian density over space– 4 time: SQCD = LQCD d x. QCD is a highly non-linear relativistic quantum field theory. It is well known that the theory has chiral symmetry in the mq = 0 limit and the symmetry is spontaneously broken in the vacuum. At high energies, it exhibits asymptotic freedom, ✩ Based on plenary talk by F.X. Lee at HYP2003, JLab. * Corresponding author. E-mail address: [email protected] (F.X. Lee). 0375-9474/$ – see front matter 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.nuclphysa.2004.12.072 F.X. -
Introduction to Subatomic- Particle Spectrometers∗
IIT-CAPP-15/2 Introduction to Subatomic- Particle Spectrometers∗ Daniel M. Kaplan Illinois Institute of Technology Chicago, IL 60616 Charles E. Lane Drexel University Philadelphia, PA 19104 Kenneth S. Nelsony University of Virginia Charlottesville, VA 22901 Abstract An introductory review, suitable for the beginning student of high-energy physics or professionals from other fields who may desire familiarity with subatomic-particle detection techniques. Subatomic-particle fundamentals and the basics of particle in- teractions with matter are summarized, after which we review particle detectors. We conclude with three examples that illustrate the variety of subatomic-particle spectrom- eters and exemplify the combined use of several detection techniques to characterize interaction events more-or-less completely. arXiv:physics/9805026v3 [physics.ins-det] 17 Jul 2015 ∗To appear in the Wiley Encyclopedia of Electrical and Electronics Engineering. yNow at Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723. 1 Contents 1 Introduction 5 2 Overview of Subatomic Particles 5 2.1 Leptons, Hadrons, Gauge and Higgs Bosons . 5 2.2 Neutrinos . 6 2.3 Quarks . 8 3 Overview of Particle Detection 9 3.1 Position Measurement: Hodoscopes and Telescopes . 9 3.2 Momentum and Energy Measurement . 9 3.2.1 Magnetic Spectrometry . 9 3.2.2 Calorimeters . 10 3.3 Particle Identification . 10 3.3.1 Calorimetric Electron (and Photon) Identification . 10 3.3.2 Muon Identification . 11 3.3.3 Time of Flight and Ionization . 11 3.3.4 Cherenkov Detectors . 11 3.3.5 Transition-Radiation Detectors . 12 3.4 Neutrino Detection . 12 3.4.1 Reactor Neutrinos . 12 3.4.2 Detection of High Energy Neutrinos . -
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.. -
Ghost-Free Scalar-Fermion Interactions
PHYSICAL REVIEW D 98, 044043 (2018) Ghost-free scalar-fermion interactions † ‡ Rampei Kimura,1,2,* Yuki Sakakihara,3, and Masahide Yamaguchi2, 1Waseda Institute for Advanced Study, Waseda University, 1-6-1 Nishi-Waseda, Shinjuku, Tokyo 169-8050, Japan 2Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan 3Department of Physics, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan (Received 15 June 2018; published 28 August 2018) We discuss a covariant extension of interactions between scalar fields and fermions in a flat space-time. We show, in a covariant theory, how to evade fermionic ghosts appearing because of the extra degrees of freedom behind a fermionic nature even in the Lagrangian with first derivatives. We will give a concrete example of a quadratic theory with up to the first derivative of multiple scalar fields and a Weyl fermion. We examine not only the maximally degenerate condition, which makes the number of degrees of freedom correct, but also a supplementary condition guaranteeing that the time evolution takes place properly. We also show that proposed derivative interaction terms between scalar fields and a Weyl fermion cannot be removed by field redefinitions. DOI: 10.1103/PhysRevD.98.044043 I. INTRODUCTION scalar-tensor theories [4–6,13–20], vector-tensor theories [21–29], and form fields [30–32]. Construction of general theory without ghost degrees of On the other hand, generic theory with fermionic d.o.f. freedom (d.o.f.) has been discussed for a long time. has not yet been investigated well. If we could find such According to Ostrogradsky’s theorem, a ghost always appears in a higher (time) derivative theory as long as it fermionic theories which have not been explored, some is nondegenerate [1] (see also Ref. -
Arxiv:1908.02416V2 [Hep-Th] 21 Aug 2019
ACFI-T19-08 Unitarity, stability and loops of unstable ghosts John F. Donoghue∗ Department of Physics, University of Massachusetts Amherst, MA 01003, USA Gabriel Menezesy Department of Physics, University of Massachusetts Amherst, MA 01003, USA and Departamento de F´ısica, Universidade Federal Rural do Rio de Janeiro, 23897-000, Serop´edica, RJ, Brazil We present a new understanding of the unstable ghost-like resonance which appears in theories such as quadratic gravity and Lee-Wick type theories. Quantum corrections make this resonance unstable, such that it does not appear in the asymptotic spectrum. We prove that these theories are unitary to all orders. Unitarity is satisfied by the inclusion of only cuts from stable states in the unitarity sum. This removes the need to consider this as a ghost state in the unitarity sum. However, we often use a narrow-width approximation where we do include cuts through unstable states, and ignore cuts through the stable decay products. If we do this with the unstable ghost resonance at one loop, we get the correct answer only by using a contour which was originally defined by Lee and Wick. The quantum effects also provide damping in both the Feynman and the retarded propagators, leading to stability under perturbations. 1. INTRODUCTION Theories such as quadratic gravity [1{19] and Lee-Wick theories [20{28] have propagators which contain both quadratic and quartic momentum dependence. In addition to the pole at q2 = 0, this combination will produce a high mass pole, via 1 1 1 = − : (1) 2 q4 q2 q2 − µ2 q − µ2 The negative sign for the second term implies that this pole is ghost-like, i.e.