DOCSLIB.ORG

Probing Extreme Electromagnetic Fields with the Breit-Wheeler Process

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Probing Extreme Electromagnetic Fields with the Breit-Wheeler Process Probing Extreme Electromagnetic Fields with the Breit-Wheeler Process Daniel Brandenburg, for the STAR Collaboration (Shandong University & BNL/CFNS) March 3, 2020 36th Winter Workshop on Nuclear Dynamics Puerto Vallarta, Mexico Outline of this Talk 1. Intro: What is the Breit-Wheeler Process? 2. Results from STAR Collaboration 3. Vacuum Birefringence in Extreme Magnetic Fields 4. The Magnetic Field in Heavy Ion Collisions 1. Measuring the “Initial” (� = 0) Magnetic Field 2. Evidence for Long-lived Magnetic Field or Medium Effects? 5. Conclusions 3/3/20 Daniel Brandenburg 2 Fundamental Interactions : Light & Matter � �⋆ �% Photo Electric Effect Bremsstrahlung Compton Scattering 1887 Hertz, Ann Phys 1895 Röntgen, Ann Phys 1906 Thomson, Conduction of (Leipzig) 31, 983 (Leipzig) 300, 1 Electricity through Gases Bethe-Heitler Pair Single Photon Dirac Annihilation Breit-Wheeler Production Annihilation 1934, Klemperer, pair production 1932, Anderson, 1933, Blackett & Proc Camb Phil Predicted 1934 Science 76,238 Occhialini, Proc R Soc 30, 347 Soc Lond A 139, 699 February 5, 2020 Daniel Brandenburg Based on slide by O. Pike 3 The Breit-Wheeler Process : �� → �)�% �- �/ o Breit-Wheeler process is by definition the lowest-order, tree level process o Two diagrams contribute at the lowest-order o t-channel process, specifically note: �+ = �-+ + �/+ February 5, 2020 Daniel Brandenburg 4 Ultra-Peripheral Heavy-Ion Collisions Ultra-relativistic charged nuclei produce highly Lorentz- contracted electromagnetic field Weizäcker-Williams Equivalent Photon Approximation (EPA): � ≈ � → In a specific phase space, transverse EM fields can be quantized as a flux of real photons Weizsacker̈ , C. F. v. Zeitschrift fur̈ Physik 88 (1934): 612 - / / � ∝ �⃗ = �×� ≈ � ≈ � � CD �� ≈ 1 → High photon density Ultra-strong electric and magnetic fields: � ≈ � → Expected magnetic field strength � ≈ ���� − ���� T Skokov, V., et. al. Int. J. Mod. Phys. A 24 (2009): 5925–32 � � Test QED under extreme conditions 3/3/20 Daniel Brandenburg 5 �� → �)�% Process in UPCs ´103 Zero Degree Calorimeter 60 Au+Au UPC Data 1 neutron 50 2 neutrons 40 3 neutrons 4 neutrons 30 Total Fit 20 dN/d(ADC Sum West ZDC) 10 0 200 400 600 800 1000 1200 ADC Sum West ZDC Breit-Wheeler �� → �)�% Mutual Coulomb excitation and pair production process nuclear dissociation • Provides efficient trigger condition →Provides high statistics sample (>6,000 �)�% pairs from data collected in 2010) → Allows for multidifferential analysis February 5, 2020 Daniel Brandenburg 6 Total �� → �)�% cross-section in the STAR Acceptance A Pure QED 2 → 2 scattering : )) 1 arXiv : 1910.12400 %M %M 2 STAR ��⁄�� ∝ � ≈ � Au+Au UPC gg® e+e- (QED) No vector meson production gg® e+e- (gEPA) → Forbidden for real photons with -1 10 gg® e+e- (STARLight) helicity ±1 (i.e. 0 is forbidden) Scale Uncertainty : ± 13% (mb/(GeV/c ) - e ) % + � �� → � � in the STAR Acceptance: -2 e 10 Data : 0.261±0.004 (stat.) ± 0.013 e ® P > 0.2 GeV/c & |he| < 1.0 dM (sys.) ± 0.034 (scale) mb g ee g |y | < 1.0 & P < 0.1 GeV/c STARLight gEPA QED ( s -3 0.22 mb 0.26 mb 0.29 mb d 10 0.5 1 1.5 2 2.5 M (GeV/c2) Measurement of total cross ee section agrees with theory STARLight: S. R. Klein, et. al. Comput. Phys. Commun. 212 (2017) 258 gEPA & QED : W. Zha, J.D.B., Z. Tang, Z. Xu arXiv:1812.02820 [nucl-th] calculations at ±�� level February 5, 2020 Daniel Brandenburg 7 Toy MC setup ØIn e+e- pair rest frame, the . is defined as the angle between positron momentum and the beam line • The . distribution for the --->e+e- has e+e- pair mass dependence �� �� → �)�%• The ⁄�cos���. distribution for the hadronic �S two-body decay is flat C 1 �� → �)�% : Individual �)/�% preferentially arXiv : 1910.12400 STAR 2 aligned along beam axis [1]: Mee = 2 GeV/c 0.4 Au+Au2 UPC 0.8 (mb) Mee = 1.2 GeV/c - gg2® e+e (XnXn)´0.88 ) / / - Mee = 0.4 GeV/c 4� 4� e 2 + - / / + Isotropic e e / 1 − / sin � cos � + / Mee = 0.01 GeV/c 4� � � ')| 0.3 e � � = 2 + 4 1 − 0.6 q / / / � ® 4� / → 1 − 1 − / cos � NOTE: for virtual photons � g g 0.2 isotropic (flat) distribution 0.4( d|cos( s o Highly virtual photon interactions should d have an isotropic distribution 0.1 0.2 2 0.4 < Mee < 0.76 GeV/c o Measure �S, the angle between the �) and the beam axis in the pair rest frame. 0 0 0 0.2 0.4 0.6 0.8 0 0.5 1 1.5 2 2.5 3 12/6/17 |cos(q')| 3 q for gg->e+e- process [1] S. Brodsky, T. Kinoshita and H. Terazawa, Phys. Rev. D4, 1532 (1971) STARLight: S. R. Klein, et. al. Comput. Phys. Commun. 212 (2017) 258 February 5, 2020 Daniel Brandenburg 8 �� �� → �)�% ⁄���� �S C �� → �)�% : Individual �)/�% preferentially arXiv : 1910.12400 STAR aligned along beam axis [1]: 0.4 Au+Au UPC (mb) gg® e+e- (XnXn)´0.88 ) / / - 4� 4� e + - / / + Isotropic e e / 1 − / sin � cos � + / 4� � � ')| 0.3 e � � = 2 + 4 1 − q / / / � ® 4� / 1 − 1 − / cos � � g g 0.2 ( d|cos( s o Highly virtual photon interactions should d 0.1 have an isotropic distribution 2 0.4 < Mee < 0.76 GeV/c o Measure �S, the angle between the �) and the 0 beam axis in the pair rest frame. 0 0.2 0.4 0.6 0.8 |cos(q')| ⇒Data are fully consistent with �(�) distribution expected for �� → �)�% [1] S. Brodsky, T. Kinoshita and H. Terazawa, Phys. Rev. D4, 1532 (1971) ⇒Measurably distinct from isotropic STARLight: S. R. Klein, et. al. Comput. Phys. Commun. 212 (2017) 258 distribution February 5, 2020 Daniel Brandenburg 9 ) % �� �� → � � ⁄��+ B arXiv : 1910.12400 o High precision data – test theory 5 STAR predictions Au+Au UPC o STARLight predicts significantly 4 gg® e+e- (STARLight) lower ⟨�+⟩ than seen in data 3 arXiv : 1910.12400 (mb/(GeV/c)) ) - e + 2 e ® dP g 1 g 2 0.4 < Mee < 0.76 GeV/c ( s d 0 0 0.02 0.04 0.06 0.08 0.1 P (GeV/c) QED and STARLight are scaled to match measured �(�� → �)�%) STARLight: S. R. Klein, et. al. Comput. Phys. Commun. 212 (2017) 258 QED : W. Zha, J.D.B., Z. Tang, Z. Xu arXiv:1812.02820 [nucl-th] February 5, 2020 Daniel Brandenburg 10 ) % �� �� → � � ⁄��+ B arXiv : 1910.12400 o Data are well described by 5 STAR leading order QED ) % Au+Au UPC calculation (�� → � � ) with + - 4 gg® e e (QED) quasi-real photons + - gg® e e (STARLight) o STARLight predicts significantly 3 arXiv : 1910.12400 (mb/(GeV/c)) lower ⟨�+⟩ than seen in data ) - STARLight calculations do not have e o + 2 centrality-dependent �+ e distribution ® dP g 1 g 2 0.4 < Mee < 0.76 GeV/c ( s o Experimentally investigate d 0 0 0.02 0.04 0.06 0.08 0.1 impact parameter dependence : P (GeV/c) Compare UPC to peripheral ) % → QED and STARLight are scaled to match measured �(�� → � � ) collisions (come back to later) STARLight: S. R. Klein, et. al. Comput. Phys. Commun. 212 (2017) 258 QED : W. Zha, J.D.B., Z. Tang, Z. Xu arXiv:1812.02820 [nucl-th] 11/05/19 Daniel Brandenburg 11 Classical Electromagnetism • Maxwell’s equations are linear ØSuperposition principle holds 1 �/ �ℒfghiijfhg ℒ = − �/ � = � = �l� fghiijfhg / �� 2�l � 1 �ℒfghiijfhg � = � � = − �l �� → Unique speed of light in vacuum: - � = = 299792458 m/s qDCD February 5, 2020 Daniel Brandenburg 12 Quantum Electrodynamics Three important discoveries that alter the classical picture: o Einstein’s energy-mass equivalence: � = ��/ o Uncertainty principle: Δ�Δ� ≥ ℏ/2 Einstein o Existence of positron : Dirac predicts negative electron energy states (1928), Anderson discovered positron in 1932 Anderson February 5, 2020 Daniel Brandenburg 13 Quantum Electrodynamics Three important discoveries that alter the classical picture: o Einstein’s energy-mass equivalence: � = ��/ o Uncertainty principle: Δ�Δ� ≥ ℏ/2 Einstein o Existence of positron : Dirac predicts negative electron energy states (1928), Anderson discovered positron in 1932 → Vacuum fluctuations o 1936: Euler & Heisenberg present modified Lagrangian | | / - z / }~ z / z ℒz{ = | − � + | − � + 7 ⋅ � + ⋯ /CD f CD f f Anderson oNon-linear → Superposition principle is broken! NB: in 1951 Shwinger derived the Lagrangian within QED formalism February 5, 2020 Daniel Brandenburg 14 Vacuum Magnetic Birefringence - � = BUT � ≠ � and � ≠ � qC ∥ + ∥ + Light behaves as if it is traveling through a medium with an index of refraction �ƒhf ≠ 1 Guido Zavattini ICNFP2019 February 5, 2020 Daniel Brandenburg 15 wikipedia Optical Birefringence Birefringent material: Different index of refraction for light polarized parallel (�∥) vs. perpendicular (�+) to material’s ordinary axis → splitting of wave function when �� = �∥ − �+ ≠ � Birefringent Material Linearly polarized (vertical) Ordinary ray Extra-ordinary ray Linearly polarized (horizontal) February 5, 2020 Daniel Brandenburg 16 Vacuum Birefringence Vacuum birefringence : Predicted in 1936 by Heisenberg & Euler. Index of refraction for � interaction with �-field depends on relative polarization angle i.e. �� = �∥ − �+ ≠ � Empty space + R. P. Mignani, et al., Mon. Not. Roy. Astron. Soc. 465 (2017), 492 Ultra-strong Magnetic Field Linearly polarized (vertical) Linearly polarized (horizontal) February 5, 2020 Daniel Brandenburg 17 Birefringence of the QED Vacuum Vacuum birefringence : Index of refraction Feynman Diagram for Vacuum Birefringence for � interaction with �-field depends on relative polarization angle i.e. �� = �∥ − �+ ≠ � � from � Lorentz contraction of EM fields → Quasi-real photons should be linearly polarized (� ⊥ � ⊥ �) Recently realized that a consequence of Probe � Observed � ) % �∥ − �+ ≠ � in �� → � � collisions is a ��� ��� modulation [3] between the pair momentum and the daughter momentum. ����(�) = transmission process �� → �� ����(�) = absorption process �� → �)�% (diagram cut) Can we observe vacuum birefringence [1]S. Bragin, et. al., Phys. Rev. Lett. 119 (2017), 250403 [2]R. P. Mignani, et al., Mon. Not. Roy. Astron. Soc. 465 (2017), 492 in ultra-peripheral collisions? [3] C. Li, J. Zhou, Y.-j. Zhou, Phys. Lett. B 795, 576 (2019) February 5, 2020 Daniel Brandenburg 18 [1] C.
Load more

Recommended publications
  • College of San Mateo Observatory Stellar Spectra Catalog ______
    College of San Mateo Observatory Stellar Spectra Catalog SGS Spectrograph Spectra taken from CSM observatory using SBIG Self Guiding Spectrograph (SGS) ___________________________________________________ A work in progress compiled by faculty, staff, and students. Stellar Spectroscopy Stars are divided into different spectral types, which result from varying atomic-level activity on the star, due to its surface temperature. In spectroscopy, we measure this activity via a spectrograph/CCD combination, attached to a moderately sized telescope. The resultant data are converted to graphical format for further analysis. The main spectral types are characterized by the letters O,B,A,F,G,K, & M. Stars of O type are the hottest, as well as the rarest. Stars of M type are the coolest, and by far, the most abundant. Each spectral type is also divided into ten subtypes, ranging from 0 to 9, further delineating temperature differences. Type Temperature Color O 30,000 - 60,000 K Blue B 10,000 - 30,000 K Blue-white A 7,500 - 10,000 K White F 6,000 - 7,500 K Yellow-white G 5,000 - 6,000 K Yellow K 3,500 - 5,000 K Yellow-orange M >3,500 K Red Class Spectral Lines O -Weak neutral and ionized Helium, weak Hydrogen, a relatively smooth continuum with very few absorption lines B -Weak neutral Helium, stronger Hydrogen, an otherwise relatively smooth continuum A -No Helium, very strong Hydrogen, weak CaII, the continuum is less smooth because of weak ionized metal lines F -Strong Hydrogen, strong CaII, weak NaI, G-band, the continuum is rougher because of many ionized metal lines G -Weaker Hydrogen, strong CaII, stronger NaI, many ionized and neutral metals, G-band is present K -Very weak Hydrogen, strong CaII, strong NaI and many metals G- band is present M -Strong TiO molecular bands, strongest NaI, weak CaII very weak Hydrogen absorption.
    [Show full text]
  • The Massless Two-Loop Two-Point Function and Zeta Functions in Counterterms of Feynman Diagrams
    The Massless Two-loop Two-point Function and Zeta Functions in Counterterms of Feynman Diagrams Dissertation zur Erlangung des Grades \Doktor der Naturwissenschaften" am Fachbereich Physik der Johannes-Gutenberg-Universit¨at in Mainz Isabella Bierenbaum geboren in Landau/Pfalz Mainz, Februar 2005 Datum der mundlic¨ hen Prufung:¨ 6. Juni 2005 D77 (Diss. Universit¨at Mainz) Contents 1 Introduction 1 2 Renormalization 3 2.1 General introduction . 3 2.2 Feynman diagrams and power counting . 5 2.3 Dimensional regularization . 9 2.4 Counterterms . 10 2.4.1 One-loop diagrams . 10 2.4.2 Multi-loop diagrams . 11 3 Hopf and Lie algebra 15 3.1 The Hopf algebras HR and HF G . 15 3.1.1 The Hopf algebra of rooted trees HR . 16 3.1.2 The Hopf algebra of Feynman graphs HF G . 20 3.1.3 Correspondence between HR, HF G, and ZFF . 20 3.2 Lie algebras . 24 4 The massless two-loop two-point function | an overview 27 4.1 General remarks . 27 4.2 Integer exponents νi | the triangle relation . 29 4.3 Non-integer exponents νi . 32 5 Nested sums 37 5.1 Nested sums . 38 5.1.1 From polylogarithms to multiple polylogarithms . 38 5.1.2 Algebraic relations: shuffle and quasi-shuffle . 41 5.2 nestedsums | the theory and some of its functions . 45 5.2.1 nestedsums | the general idea . 46 5.2.2 nestedsums | the four classes of functions . 48 6 The massless two-loop two-point function 53 6.1 The expansion of I^(2;5) . 53 6.1.1 Decomposition of I^(2;5) .
    [Show full text]
  • Binary Star Modeling: a Computational Approach
    TCNJ JOURNAL OF STUDENT SCHOLARSHIP VOLUME XIV APRIL 2012 BINARY STAR MODELING: A COMPUTATIONAL APPROACH Author: Daniel Silano Faculty Sponsor: R. J. Pfeiffer, Department of Physics ABSTRACT This paper illustrates the equations and computational logic involved in writing BinaryFactory, a program I developed in Spring 2011 in collaboration with Dr. R. J. Pfeiffer, professor of physics at The College of New Jersey. This paper outlines computational methods required to design a computer model which can show an animation and generate an accurate light curve of an eclipsing binary star system. The final result is a light curve fit to any star system using BinaryFactory. An example is given for the eclipsing binary star system TU Muscae. Good agreement with observational data was obtained using parameters obtained from literature published by others. INTRODUCTION This project started as a proposal for a simple animation of two stars orbiting one another in C++. I found that although there was software that generated simple animations of binary star orbits and generated light curves, the commercial software was prohibitively expensive or not very user friendly. As I progressed from solving the orbits to generating the Roche surface to generating a light curve, I learned much about computational physics. There were many trials along the way; this paper aims to explain to the reader how a computational model of binary stars is made, as well as how to avoid pitfalls I encountered while writing BinaryFactory. Binary Factory was written in C++ using the free C++ libraries, OpenGL, GLUT, and GLUI. A basis for writing a model similar to BinaryFactory in any language will be presented, with a light curve fit for the eclipsing binary star system TU Muscae in the final secion.
    [Show full text]
  • De-Coding Starlight (Grades 5-8)
    Teacher's Guide to Chandra X-ray Observatory From Pixels to Images: De-Coding Starlight (Grades 5-8) Background and Purpose In an effort to learn more about black holes, pulsars, supernovas, and other high-energy astronomical events, NASA launched the Chandra X-ray Observatory in 1999. Chandra is the largest space telescope ever launched and detects "invisible" X-ray radiation, which is often the only way that scientists can pinpoint and understand high-energy events in our universe. Computer aided data collection and processing is an essential facet to astronomical research using space- and ground-based telescopes. Every 8 hours, Chandra downloads millions of pieces of information to Earth. To control, process, and analyze this flood of numbers, scientists rely on computers, not only to do calculations, but also to change numbers into pictures. The final results of these analyses are wonderful and exciting images that expand understanding of the universe for not only scientists, but also decision-makers and the general public. Although computers are used extensively, scientists and programmers go through painstaking calibration and validation processes to ensure that computers produce technically correct images. As Dr. Neil Comins so eloquently states1, “These images create an impression of the glamour of science in the public mind that is not entirely realistic. The process of transforming [i.e., by using computers] most telescope data into accurate and meaningful images is long, involved, unglamorous, and exacting. Make a mistake in one of dozens of parameters or steps in the analysis and you will get inaccurate results.” The process of making the computer-generated images from X-ray data collected by Chandra involves the use of "false color." X-rays cannot be seen by human eyes, and therefore, have no "color." Visual representation of X-ray data, as well as radio, infrared, ultraviolet, and gamma, involves the use of "false color" techniques, where colors in the image represent intensity, energy, temperature, or another property of the radiation.
    [Show full text]
  • Arxiv:1202.1557V1
    The Heisenberg-Euler Effective Action: 75 years on ∗ Gerald V. Dunne Physics Department, University of Connecticut, Storrs, CT 06269-3046, USA On this 75th anniversary of the publication of the Heisenberg-Euler paper on the full non- perturbative one-loop effective action for quantum electrodynamics I review their paper and discuss some of the impact it has had on quantum field theory. I. HISTORICAL CONTEXT After the 1928 publication of Dirac’s work on his relativistic theory of the electron [1], Heisenberg immediately appreciated the significance of the new ”hole theory” picture of the quantum vacuum of quantum electrodynamics (QED). Following some confusion, in 1931 Dirac associated the holes with positively charged electrons [2]: A hole, if there were one, would be a new kind of particle, unknown to experimental physics, having the same mass and opposite charge to an electron. With the discovery of the positron in 1932, soon thereafter [but, interestingly, not immediately [3]], Dirac proposed at the 1933 Solvay Conference that the negative energy solutions [holes] should be identified with the positron [4]: Any state of negative energy which is not occupied represents a lack of uniformity and this must be shown by observation as a kind of hole. It is possible to assume that the positrons are these holes. Positron theory and QED was born, and Heisenberg began investigating positron theory in earnest, publishing two fundamental papers in 1934, formalizing the treatment of the quantum fluctuations inherent in this Dirac sea picture of the QED vacuum [5, 6]. It was soon realized that these quantum fluctuations would lead to quantum nonlinearities [6]: Halpern and Debye have already independently drawn attention to the fact that the Dirac theory of the positron leads to the scattering of light by light, even when the energy of the photons is not sufficient to create pairs.
    [Show full text]
  • Vacuum Energy
    Vacuum Energy Mark D. Roberts, 117 Queen’s Road, Wimbledon, London SW19 8NS, Email:[email protected] http://cosmology.mth.uct.ac.za/ roberts ∼ February 1, 2008 Eprint: hep-th/0012062 Comments: A comprehensive review of Vacuum Energy, which is an extended version of a poster presented at L¨uderitz (2000). This is not a review of the cosmolog- ical constant per se, but rather vacuum energy in general, my approach to the cosmological constant is not standard. Lots of very small changes and several additions for the second and third versions: constructive feedback still welcome, but the next version will be sometime in coming due to my sporadiac internet access. First Version 153 pages, 368 references. Second Version 161 pages, 399 references. arXiv:hep-th/0012062v3 22 Jul 2001 Third Version 167 pages, 412 references. The 1999 PACS Physics and Astronomy Classification Scheme: http://publish.aps.org/eprint/gateway/pacslist 11.10.+x, 04.62.+v, 98.80.-k, 03.70.+k; The 2000 Mathematical Classification Scheme: http://www.ams.org/msc 81T20, 83E99, 81Q99, 83F05. 3 KEYPHRASES: Vacuum Energy, Inertial Mass, Principle of Equivalence. 1 Abstract There appears to be three, perhaps related, ways of approaching the nature of vacuum energy. The first is to say that it is just the lowest energy state of a given, usually quantum, system. The second is to equate vacuum energy with the Casimir energy. The third is to note that an energy difference from a complete vacuum might have some long range effect, typically this energy difference is interpreted as the cosmological constant.
    [Show full text]
  • Research on Eclipsing Binary Star in Constellation of Taurus “WY Tau” Avery Mcchristian Advisor: Dr Shaukat Goderya
    Astronomy at Tarleton State University: A study of Eclipsing Binary Star (WY TAU) in the constellation of Taurus the Bull Avery McChristian Advisor: Dr Shaukat Goderya Types of Eclipsing Binary What is a Binary Star Stars Observation and Analysis A binary star is a stellar system consisting of two stars which The data on “WY TAU” was gathered in November and orbit around a common point, called the center of mass. The December of 2006 using Tarleton State’s observatory. two stars are gravitationally bound to each other. It has been Contact 1,008 images were collected over nine nights. The estimated that more than half of all stars in our galaxy are images were taken under two different filters; 507 were binary stars. Binary stars play a vital role in our taken using a Visual band pass filter and 501 were understanding of the evolution and physics of stars. When taken using a Blue band pass filter. Using “Astronomical studied they can provide important data on the mass of each Image Processing for Windows” software we were able individual star. It is possible to obtain this information only if Semi Detached to extract the Julian date and magnitude from the raw both spectroscopic and photometric study of the system is images. We then used excel to convert time, or Julian performed. Spectroscopic study enables the determination of date, into phase and magnitude into intensity. Using the absolute parameters of the binary system. phase and intensity figures we were able to construct the observed light curve. Upon inspection of the light curve we realized the period and epoch needed Detached corrections.
    [Show full text]
  • The QED Coupling Constant for an Electron to Emit Or Absorb a Photon Is Shown to Be the Square Root of the Fine Structure Constant Α Shlomo Barak
    The QED Coupling Constant for an Electron to Emit or Absorb a Photon is Shown to be the Square Root of the Fine Structure Constant α Shlomo Barak To cite this version: Shlomo Barak. The QED Coupling Constant for an Electron to Emit or Absorb a Photon is Shown to be the Square Root of the Fine Structure Constant α. 2020. hal-02626064 HAL Id: hal-02626064 https://hal.archives-ouvertes.fr/hal-02626064 Preprint submitted on 26 May 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. V4 15/04/2020 The QED Coupling Constant for an Electron to Emit or Absorb a Photon is Shown to be the Square Root of the Fine Structure Constant α Shlomo Barak Taga Innovations 16 Beit Hillel St. Tel Aviv 67017 Israel Corresponding author: [email protected] Abstract The QED probability amplitude (coupling constant) for an electron to interact with its own field or to emit or absorb a photon has been experimentally determined to be -0.08542455. This result is very close to the square root of the Fine Structure Constant α. By showing theoretically that the coupling constant is indeed the square root of α we resolve what is, according to Feynman, one of the greatest damn mysteries of physics.
    [Show full text]
  • RECOLORING the UNIVERSE
    National Aeronautics and Space Administration 2 De-Coding Starlight Activity: From Pixels to Images RECOLORING the UNIVERSE The Scenario You have discovered a new supernova remnant using NASA’s Chandra X-ray Observatory. The Director of NASA Deep Space Research has requested a report of your results. Unfortunately, your computer crashed fatally while you were creating an image of the supernova remnant from the numerical data. To fix this, you will create, by hand, an image of the supernova remnant. To create the image, you will use “raw” data from the Chandra satellite. You have tables of the data, but unfortunately don’t have all of it on paper so you will have to recalculate some values. In addition to the graph, you will prepare a written explanation of your discovery and answer a few questions. www.nasa.gov chandra.si.edu COMPLETE THE FOLLOWING TASKS: Calculations Your mission is to turn numbers into a picture. Before you can make the image, you will need to make some calculations. 1 The raw data for the destroyed “pixels” (grid squares containing a value and color) are listed in Table 1. Before making the image, you will need to fill in the last column of Table 1 by calculating average X-ray intensity for each pixel. After you have determined average pixel values for the destroyed pixels, write the numerical values in the proper box (pixel) of the attached grid. Many of the pixel values are already on the grid, but you have to fill in the blank pixels. This is the grid in which you will draw the image Coloring the Image Complete the following steps in coloring the image.
    [Show full text]
  • Understanding the Fully Non-Perturbative Strong-Field Regime of QED Loi to Theory Frontier Phil H
    Understanding the Fully Non-Perturbative Strong-Field Regime of QED LoI to Theory Frontier Phil H. Bucksbaum, Gerald V. Dunnea), Frederico Fiuza, Sebastian Meurenb), Michael E. Peskin, David A. Reis, Greger Torgrimsson, Glen White, and Vitaly Yakimenko (Dated: June 2020) Abstract: Although perturbative QED with small background fields is well-understood and well-tested, there is much less understanding of QED in the regime of strong fields. At 2 3 18 the Schwinger critical field, Ec = m c /e~ ∼ 10 V/m, the vacuum becomes unstable to 2/3 pair production. For stronger fields, such that α(E/Ec) > 1, QED perturbation theory breaks down. These regimes are relevant to environments found in high-energy astrophysics and to physics in the collisions of high-energy electron and heavy ion beams. We plan to investigate problems in beam simulation and basic QED theory related to QED at strong fields, to analyze experiments that can test QED in this regime, and to explore applications to astrophysics and particle physics. Perturbative QED is characterized by the vacuum electron/positron mass scale, m ∼ MeV, a large mass gap between fermions and the massless photon, and a very small coupling constant α = e2/(4π), which facilitates the perturbative expansion. For many quantities in fundamental lepton and atomic physics, the QED perturbation expansion is extremely accurate. Indeed, the precise agreement between theory and experiment for these quantities is a triumph of modern physics [1]. This picture changes profoundly in the√ presence of very strong background fields [2–8]. The back- ground field introduces a new mass scale eE∗, where E∗ is the rest-frame electric field experienced 2 by an electron/positron with charge ∓e.
    [Show full text]
  • Newsleiter I
    + THE NEWSLEITER I VOLUME IV NO. 1 1981 THE OLIVER CHALLENGE T he Monterey I nstitute for Research in Ast ronomy will soon become an important center for stellar astronorny due in large part to the determination of its staff and the generous st^pport of many individuals and companies. Thanks to donations of equipment, f oundation grants, and personal contributions, M IRA now possesses a telescope and instrumentat ion. With a use permit for Chews Ridge in the Los Padres National Forest, MIRA has access to one of the finest sites for optical astronorny in North America. But, one component of MIRA's observatory is still missing: the observatory building. ln December 1980, Dr. Bbrnard M. Oliver, recently retired Vice-President for Research and Development at Hewlett- Packard, pledged a personal challenge grant of $200,000 for the construction of M IRA's observatory building. For every dollar contributed to the building fund between now and the end of the year, Dr. oliver will donate a matching dollar. The matching of ttre Oliver Challenge by MIRA's Friends will be a maior step toward the construction of the observatory building on Chews Ridge. A native Californian educated at Stanford and the California lnstitute of Technology, Dr. oliver's interest in M IRA dates back several years. tast June, he visited Monterey to give a lecture m the 'Search for Extraterrestrial I ntelligence' to the Friends of MIRA. At that time, he visited the MIRA shop to assess the staf f 's work on the Ret icon Spect rophotqmeter and related instrumentation.
    [Show full text]
  • PREFACE Symposium 177 of the International Astronomical Union
    PREFACE Symposium 177 of the International Astronomical Union was held in late May of 1996 in the coastal city of Antalya, Turkey. It was attended by 142 scientists from 32 countries. The purpose of the symposium was to discuss the causes and effects of the composition changes that often occur in the atmospheres of cool, evolved stars such as the carbon stars in the course of their evolution. This volume includes the full texts of papers presented orally and one-page abstracts of the poster contributions. The chemical composition of a star's observable surface layers depends not only upon the composition of the interstellar medium from which it formed, but in many cases also upon the star's own history. Consequently, spectroscopic studies of starlight can tell us much about a star's origin, the path it followed as it evolved, and the physical processes of the interior which brought about the composition changes and made them visible on the surface. Furthermore, evolved stars are often surrounded by detectable shells of their own making, and the compositions of these shells provide additional clues concerning the star's evolutionary history. It was Henry Norris Russell who showed in 1934 that the gross spectro- scopic differences between the molecular spectra of carbon stars and M stars could be explained as due to a simple reversal of the abundances of oxygen and carbon. It was also realized early on that the interstellar medium is nowhere carbon-rich, and that changes in chemical composition must be the result of nuclear reactions that take place in the hot interiors of stars, not in their atmospheres.
    [Show full text]