History and Some Aspects of the Lamb Shift
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The Particle Zoo
219 8 The Particle Zoo 8.1 Introduction Around 1960 the situation in particle physics was very confusing. Elementary particlesa such as the photon, electron, muon and neutrino were known, but in addition many more particles were being discovered and almost any experiment added more to the list. The main property that these new particles had in common was that they were strongly interacting, meaning that they would interact strongly with protons and neutrons. In this they were different from photons, electrons, muons and neutrinos. A muon may actually traverse a nucleus without disturbing it, and a neutrino, being electrically neutral, may go through huge amounts of matter without any interaction. In other words, in some vague way these new particles seemed to belong to the same group of by Dr. Horst Wahl on 08/28/12. For personal use only. particles as the proton and neutron. In those days proton and neutron were mysterious as well, they seemed to be complicated compound states. At some point a classification scheme for all these particles including proton and neutron was introduced, and once that was done the situation clarified considerably. In that Facts And Mysteries In Elementary Particle Physics Downloaded from www.worldscientific.com era theoretical particle physics was dominated by Gell-Mann, who contributed enormously to that process of systematization and clarification. The result of this massive amount of experimental and theoretical work was the introduction of quarks, and the understanding that all those ‘new’ particles as well as the proton aWe call a particle elementary if we do not know of a further substructure. -
Fotonica Ed Elettronica Quantistica
Fotonica ed elettronica quantistica http://www.dsf.unica.it/~fotonica/teaching/fotonica.html Fotonica ed elettronica quantistica Quantum optics - Quantization of electromagnetic field - Statistics of light, photon counting and noise; - HBT and correlation; g1 e g2 coherence; antibunching; single photons - Squeezing - Quantum cryptography - Quantum computer, entanglement and teleportation Light-matter Interaction - Two-level atom - Laser physics - Spectroscopy - Electronics and photonics at the nanometer scale - Cold atoms - Photodetectors - Solar cells http://www.dsf.unica.it/~fotonica/teaching/fotonica.html Energy Temperature LHC at CERN, Higgs, SUSY, ??? TeV 15 q q particle accelerators 10 K q GeV proton rest mass - quarks 1012K MeV electron rest mass / gamma rays 109K keV Nuclear Fusion, x rays, Sun center 106K Atoms ionize - visible light eV Sun surface fundamental components components fundamental room temperature 103K meV Liquid He, superconductors, space 1K dilution refrigerators, quantum Hall µeV laser-cooled atoms 10-3K neV Bose-Einstein condensates 10-6K peV low T record 480 picokelvin 10-9K -12 complexity, organization organization complexity, 10 K Nobel Prizes in Physics 2010 - Andre Geims, Konstantin Novoselov 2009 - Charles K. Kao, Willard S. Boyle, George E. Smith 2007 - Albert Fert, Peter Gruenberg 2005 - Roy J. Glauber, John L. Hall, Theodor W. Hänsch 2001 - Eric A. Cornell, Wolfgang Ketterle, Carl E. Wieman 1997 - Steven Chu, Claude Cohen-Tannoudji, William D. Phillips 1989 - Norman F. Ramsey, Hans G. Dehmelt, Wolfgang Paul 1981 - Nicolaas Bloembergen, Arthur L. Schawlow, Kai M. Siegbahn 1966 - Alfred Kastler 1964 - Charles H. Townes, Nicolay G. Basov, Aleksandr M. Prokhorov 1944 - Isidor Isaac Rabi 1930 - Venkata Raman 1921 - Albert Einstein 1907 - Albert A. -
Unit 1 Old Quantum Theory
UNIT 1 OLD QUANTUM THEORY Structure Introduction Objectives li;,:overy of Sub-atomic Particles Earlier Atom Models Light as clectromagnetic Wave Failures of Classical Physics Black Body Radiation '1 Heat Capacity Variation Photoelectric Effect Atomic Spectra Planck's Quantum Theory, Black Body ~diation. and Heat Capacity Variation Einstein's Theory of Photoelectric Effect Bohr Atom Model Calculation of Radius of Orbits Energy of an Electron in an Orbit Atomic Spectra and Bohr's Theory Critical Analysis of Bohr's Theory Refinements in the Atomic Spectra The61-y Summary Terminal Questions Answers 1.1 INTRODUCTION The ideas of classical mechanics developed by Galileo, Kepler and Newton, when applied to atomic and molecular systems were found to be inadequate. Need was felt for a theory to describe, correlate and predict the behaviour of the sub-atomic particles. The quantum theory, proposed by Max Planck and applied by Einstein and Bohr to explain different aspects of behaviour of matter, is an important milestone in the formulation of the modern concept of atom. In this unit, we will study how black body radiation, heat capacity variation, photoelectric effect and atomic spectra of hydrogen can be explained on the basis of theories proposed by Max Planck, Einstein and Bohr. They based their theories on the postulate that all interactions between matter and radiation occur in terms of definite packets of energy, known as quanta. Their ideas, when extended further, led to the evolution of wave mechanics, which shows the dual nature of matter -
The Lamb Shift Experiment in Muonic Hydrogen
The Lamb Shift Experiment in Muonic Hydrogen Dissertation submitted to the Physics Faculty of the Ludwig{Maximilians{University Munich by Aldo Sady Antognini from Bellinzona, Switzerland Munich, November 2005 1st Referee : Prof. Dr. Theodor W. H¨ansch 2nd Referee : Prof. Dr. Dietrich Habs Date of the Oral Examination : December 21, 2005 Even if I don't think, I am. Itsuo Tsuda Je suis ou` je ne pense pas, je pense ou` je ne suis pas. Jacques Lacan A mia mamma e mio papa` con tanto amore Abstract The subject of this thesis is the muonic hydrogen (µ−p) Lamb shift experiment being performed at the Paul Scherrer Institute, Switzerland. Its goal is to measure the 2S 2P − energy difference in µp atoms by laser spectroscopy and to deduce the proton root{mean{ −3 square (rms) charge radius rp with 10 precision, an order of magnitude better than presently known. This would make it possible to test bound{state quantum electrody- namics (QED) in hydrogen at the relative accuracy level of 10−7, and will lead to an improvement in the determination of the Rydberg constant by more than a factor of seven. Moreover it will represent a benchmark for QCD theories. The experiment is based on the measurement of the energy difference between the F=1 F=2 2S1=2 and 2P3=2 levels in µp atoms to a precision of 30 ppm, using a pulsed laser tunable at wavelengths around 6 µm. Negative muons from a unique low{energy muon beam are −1 stopped at a rate of 70 s in 0.6 hPa of H2 gas. -
Quantum Theory of the Hydrogen Atom
Quantum Theory of the Hydrogen Atom Chemistry 35 Fall 2000 Balmer and the Hydrogen Spectrum n 1885: Johann Balmer, a Swiss schoolteacher, empirically deduced a formula which predicted the wavelengths of emission for Hydrogen: l (in Å) = 3645.6 x n2 for n = 3, 4, 5, 6 n2 -4 •Predicts the wavelengths of the 4 visible emission lines from Hydrogen (which are called the Balmer Series) •Implies that there is some underlying order in the atom that results in this deceptively simple equation. 2 1 The Bohr Atom n 1913: Niels Bohr uses quantum theory to explain the origin of the line spectrum of hydrogen 1. The electron in a hydrogen atom can exist only in discrete orbits 2. The orbits are circular paths about the nucleus at varying radii 3. Each orbit corresponds to a particular energy 4. Orbit energies increase with increasing radii 5. The lowest energy orbit is called the ground state 6. After absorbing energy, the e- jumps to a higher energy orbit (an excited state) 7. When the e- drops down to a lower energy orbit, the energy lost can be given off as a quantum of light 8. The energy of the photon emitted is equal to the difference in energies of the two orbits involved 3 Mohr Bohr n Mathematically, Bohr equated the two forces acting on the orbiting electron: coulombic attraction = centrifugal accelleration 2 2 2 -(Z/4peo)(e /r ) = m(v /r) n Rearranging and making the wild assumption: mvr = n(h/2p) n e- angular momentum can only have certain quantified values in whole multiples of h/2p 4 2 Hydrogen Energy Levels n Based on this model, Bohr arrived at a simple equation to calculate the electron energy levels in hydrogen: 2 En = -RH(1/n ) for n = 1, 2, 3, 4, . -
External Fields and Measuring Radiative Corrections
Quantum Electrodynamics (QED), Winter 2015/16 Radiative corrections External fields and measuring radiative corrections We now briefly describe how the radiative corrections Πc(k), Σc(p) and Λc(p1; p2), the finite parts of the loop diagrams which enter in renormalization, lead to observable effects. We will consider the two classic cases: the correction to the electron magnetic moment and the Lamb shift. Both are measured using a background electric or magnetic field. Calculating amplitudes in this situation requires a modified perturbative expansion of QED from the one we have considered thus far. Feynman rules with external fields An important approximation in QED is where one has a large background electromagnetic field. This external field can effectively be treated as a classical background in which we quantise the fermions (in analogy to including an electromagnetic field in the Schrodinger¨ equation). More formally we can always expand the field operators around a non-zero value (e) Aµ = aµ + Aµ (e) where Aµ is a c-number giving the external field and aµ is the field operator describing the fluctua- tions. The S-matrix is then given by R 4 ¯ (e) S = T eie d x : (a=+A= ) : For a static external field (independent of time) we have the Fourier transform representation Z (e) 3 ik·x (e) Aµ (x) = d= k e Aµ (k) We can now consider scattering processes such as an electron interacting with the background field. We find a non-zero amplitude even at first order in the perturbation expansion. (Without a background field such terms are excluded by energy-momentum conservation.) We have Z (1) 0 0 4 (e) hfj S jii = ie p ; s d x : ¯A= : jp; si Z 4 (e) 0 0 ¯− µ + = ie d x Aµ (x) p ; s (x)γ (x) jp; si Z Z 4 3 (e) 0 µ ik·x+ip0·x−ip·x = ie d x d= k Aµ (k)u ¯s0 (p )γ us(p) e ≡ 2πδ(E0 − E)M where 0 (e) 0 M = ieu¯s0 (p )A= (p − p)us(p) We see that energy is conserved in the scattering (since the external field is static) but in general the initial and final 3-momenta of the electron can be different. -
Identical Particles
8.06 Spring 2016 Lecture Notes 4. Identical particles Aram Harrow Last updated: May 19, 2016 Contents 1 Fermions and Bosons 1 1.1 Introduction and two-particle systems .......................... 1 1.2 N particles ......................................... 3 1.3 Non-interacting particles .................................. 5 1.4 Non-zero temperature ................................... 7 1.5 Composite particles .................................... 7 1.6 Emergence of distinguishability .............................. 9 2 Degenerate Fermi gas 10 2.1 Electrons in a box ..................................... 10 2.2 White dwarves ....................................... 12 2.3 Electrons in a periodic potential ............................. 16 3 Charged particles in a magnetic field 21 3.1 The Pauli Hamiltonian ................................... 21 3.2 Landau levels ........................................ 23 3.3 The de Haas-van Alphen effect .............................. 24 3.4 Integer Quantum Hall Effect ............................... 27 3.5 Aharonov-Bohm Effect ................................... 33 1 Fermions and Bosons 1.1 Introduction and two-particle systems Previously we have discussed multiple-particle systems using the tensor-product formalism (cf. Section 1.2 of Chapter 3 of these notes). But this applies only to distinguishable particles. In reality, all known particles are indistinguishable. In the coming lectures, we will explore the mathematical and physical consequences of this. First, consider classical many-particle systems. If a single particle has state described by position and momentum (~r; p~), then the state of N distinguishable particles can be written as (~r1; p~1; ~r2; p~2;:::; ~rN ; p~N ). The notation (·; ·;:::; ·) denotes an ordered list, in which different posi tions have different meanings; e.g. in general (~r1; p~1; ~r2; p~2)6 = (~r2; p~2; ~r1; p~1). 1 To describe indistinguishable particles, we can use set notation. -
A Brief Tour Into the History of Gravity: from Emocritus to Einstein
American Journal of Space Science 1 (1): 33-45, 2013 ISSN: 1948-9927 © 2013 Science Publications doi:10.3844/ajssp.2013.33.45 Published Online 1 (1) 2013 (http://www.thescipub.com/ajss.toc) A Brief Tour into the History of Gravity: From Emocritus to Einstein Panagiotis Papaspirou and Xenophon Moussas Department of Physics, Section of Astrophysics, Astronomy and Mechanics, University of Athens, Athens, Greece ABSTRACT The History of Gravity encompasses many different versions of the idea of the Gravitational interaction, which starts already from the Presocratic Atomists, continues to the doctrines of the Platonic and Neoplatonic School and of the Aristotelian School, passes through the works of John Philoponus and John Bouridan and reaches the visions of Johannes Kepler and Galileo Galilei. Then, the major breakthrough in the Theory of Motion and the Theory of Gravity takes place within the realm of Isaac Newton’s most famous Principia and of the work of Gottfried Leibniz, continues with the contributions of the Post- newtonians, such as Leonhard Euler, reaches the epoch of its modern formulation by Ernst Mach and other Giants of Physics and Philosophy of this epoch, enriches its structure within the work of Henry Poincare and finally culminates within the work of Albert Einstein, with the formulation of the Theory of Special Relativity and of General Relativity at the begin of the 20th century. The evolution of the Theory of General Relativity still continues up to our times, is rich in forms it takes and full of ideas of theoretical strength. Many fundamental concepts of the Epistemology and the History of Physics appear in the study of the Theory of Gravity, such as the notions of Space, of Time, of Motion, of Mass, in its Inertial, Active Gravitational and Passive Gravitational form, of the Inertial system of reference, of the Force, of the Field, of the Riemannian Geometry and of the Field Equations. -
Lecture Notes Particle Physics II Quantum Chromo Dynamics 6
Lecture notes Particle Physics II Quantum Chromo Dynamics 6. Feynman rules and colour factors Michiel Botje Nikhef, Science Park, Amsterdam December 7, 2012 Colour space We have seen that quarks come in three colours i = (r; g; b) so • that the wave function can be written as (s) µ ci uf (p ) incoming quark 8 (s) µ ciy u¯f (p ) outgoing quark i = > > (s) µ > cy v¯ (p ) incoming antiquark <> i f c v(s)(pµ) outgoing antiquark > i f > Expressions for the> 4-component spinors u and v can be found in :> Griffiths p.233{4. We have here explicitly indicated the Lorentz index µ = (0; 1; 2; 3), the spin index s = (1; 2) = (up; down) and the flavour index f = (d; u; s; c; b; t). To not overburden the notation we will suppress these indices in the following. The colour index i is taken care of by defining the following basis • vectors in colour space 1 0 0 c r = 0 ; c g = 1 ; c b = 0 ; 0 1 0 1 0 1 0 0 1 @ A @ A @ A for red, green and blue, respectively. The Hermitian conjugates ciy are just the corresponding row vectors. A colour transition like r g can now be described as an • ! SU(3) matrix operation in colour space. Recalling the SU(3) step operators (page 1{25 and Exercise 1.8d) we may write 0 0 0 0 1 cg = (λ1 iλ2) cr or, in full, 1 = 1 0 0 0 − 0 1 0 1 0 1 0 0 0 0 0 @ A @ A @ A 6{3 From the Lagrangian to Feynman graphs Here is QCD Lagrangian with all colour indices shown.29 • µ 1 µν a a µ a QCD = (iγ @µ m) i F F gs λ j γ A L i − − 4 a µν − i ij µ µν µ ν ν µ µ ν F = @ A @ A 2gs fabcA A a a − a − b c We have introduced here a second colour index a = (1;:::; 8) to label the gluon fields and the corresponding SU(3) generators. -
Muonium-Antimuonium Conversion Abstract
SciPost Phys. Proc. 5, 009 (2021) Muonium-antimuonium conversion Lorenz Willmann? and Klaus Jungmann Van Swinderen Institute, University of Groningen, 9747 AA, Groningen, The Netherlands ? [email protected] Review of Particle Physics at PSI doi:10.21468/SciPostPhysProc.5 Abstract The MACS experiment performed at PSI in the 1990s provided an yet unchallenged upper bound on the probability for a spontaneous conversion of the muonium atom, + + M =(µ e−), into its antiatom, antimuonium M =(µ−e ). It comprises the culmination of a series of measurements at various accelerator laboratories worldwide. The experimen- tal limits on the process have provided input and steering for the further development of a variety of theoretical models beyond the standard theory, in particular for mod- els which address lepton number violating processes and matter-antimatter oscillations. Several models beyond the standard theory could be strongly disfavored. There is inter- est in a new measurement and improved sensitivity could be reached by exploiting the time evolution of the conversion process, e.g., at intense pulsed muonium sources. Copyright L. Willmann and K. Jungmann. Received 16-02-2021 This work is licensed under the Creative Commons Accepted 28-04-2021 Check for Attribution 4.0 International License. Published 06-09-2021 updates Published by the SciPost Foundation. doi:10.21468/SciPostPhysProc.5.009 9.1 Introduction + The bound state of a positive muon (µ ) and an electron (e−) is an exotic atom which has been named muonium (M) by V.Telegdi. This exotic atom was first produced and observed by V.W. Hughes and collaborators in 1960 [1]. -
Casimir Effect Mechanism of Pairing Between Fermions in the Vicinity of A
Casimir effect mechanism of pairing between fermions in the vicinity of a magnetic quantum critical point Yaroslav A. Kharkov1 and Oleg P. Sushkov1 1School of Physics, University of New South Wales, Sydney 2052, Australia We consider two immobile spin 1/2 fermions in a two-dimensional magnetic system that is close to the O(3) magnetic quantum critical point (QCP) which separates magnetically ordered and disordered phases. Focusing on the disordered phase in the vicinity of the QCP, we demonstrate that the criticality results in a strong long range attraction between the fermions, with potential V (r) 1/rν , ν 0.75, where r is separation between the fermions. The mechanism of the enhanced∝ − attraction≈ is similar to Casimir effect and corresponds to multi-magnon exchange processes between the fermions. While we consider a model system, the problem is originally motivated by recent establishment of magnetic QCP in hole doped cuprates under the superconducting dome at doping of about 10%. We suggest the mechanism of magnetic critical enhancement of pairing in cuprates. PACS numbers: 74.40.Kb, 75.50.Ee, 74.20.Mn I. INTRODUCTION in the frame of normal Fermi liquid picture (large Fermi surface). Within this approach electrons interact via ex- change of an antiferromagnetic (AF) fluctuation (param- In the present paper we study interaction between 11 fermions mediated by magnetic fluctuations in a vicin- agnon). The lightly doped AF Mott insulator approach, ity of magnetic quantum critical point. To address this instead, necessarily implies small Fermi surface. In this case holes interact/pair via exchange of the Goldstone generic problem we consider a specific model of two holes 12 injected into the bilayer antiferromagnet. -
Charge Radius of the Short-Lived Ni68 and Correlation with The
PHYSICAL REVIEW LETTERS 124, 132502 (2020) Charge Radius of the Short-Lived 68Ni and Correlation with the Dipole Polarizability † S. Kaufmann,1 J. Simonis,2 S. Bacca,2,3 J. Billowes,4 M. L. Bissell,4 K. Blaum ,5 B. Cheal,6 R. F. Garcia Ruiz,4,7, W. Gins,8 C. Gorges,1 G. Hagen,9 H. Heylen,5,7 A. Kanellakopoulos ,8 S. Malbrunot-Ettenauer,7 M. Miorelli,10 R. Neugart,5,11 ‡ G. Neyens ,7,8 W. Nörtershäuser ,1,* R. Sánchez ,12 S. Sailer,13 A. Schwenk,1,5,14 T. Ratajczyk,1 L. V. Rodríguez,15, L. Wehner,16 C. Wraith,6 L. Xie,4 Z. Y. Xu,8 X. F. Yang,8,17 and D. T. Yordanov15 1Institut für Kernphysik, Technische Universität Darmstadt, D-64289 Darmstadt, Germany 2Institut für Kernphysik and PRISMA+ Cluster of Excellence, Johannes Gutenberg-Universität Mainz, D-55128 Mainz, Germany 3Helmholtz Institute Mainz, GSI Helmholtzzentrum für Schwerionenforschung GmbH, D-64291 Darmstadt, Germany 4School of Physics and Astronomy, The University of Manchester, Manchester, M13 9PL, United Kingdom 5Max-Planck-Institut für Kernphysik, D-69117 Heidelberg, Germany 6Oliver Lodge Laboratory, Oxford Street, University of Liverpool, Liverpool L69 7ZE, United Kingdom 7Experimental Physics Department, CERN, CH-1211 Geneva 23, Switzerland 8KU Leuven, Instituut voor Kern- en Stralingsfysica, B-3001 Leuven, Belgium 9Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA and Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA 10TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, V6T 2A3, Canada 11Institut