DOCSLIB.ORG

Muonium - Physics of a Most Fundamental Atom Klaus P

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Muonium - Physics of a Most Fundamental Atom Klaus P 1 Muonium - Physics of a most Fundamental Atom Klaus P. Jungmanna aKernfysisch Versneller Instituut, Rijksuniversiteit Groningen, Zernikelaan 25, NL-9747 AA Groningen The hydrogen-like muonium atom (M=¹+e¡) o®ers possiblitites to measure fundamental constants most pre- cisely and to search sensitively for new physics. All experiments on muonium at the presenetly most intense muon sources are statistics limited. New and intense muon sources are indispensable for improved measurements. 1. Introduction troscopy experiments are a microwave measure- ment of the Zeeman splitting in the ground state The dominant interaction within the M atom hyper¯ne structure ¢ºHFS and a two-photon [1,2] is electromagnetic. In the framework of 2 2 laser excitation of the 1 S1=2-2 S1=2 transition. bound state Quantum Electrodynamics (QED) Both energy intervals can be calculated to very the electromagnetic part of the binding can high precision, which allows to extract fundamen- be calculated to su±ciently high accuracy for tal constants. modern high precision spectroscopy experiments. There are also contributions from weak inter- actions arising through Z0-boson exchange and 2. Hyper¯ne structure from strong interactions owing to vacuum po- The most recent experiment at LAMPF had a larization loops containing hadrons. The cor- krypton gas target inside of a microwave cavity responding energy level shifts can be obtained at typically atmospheric density and in a homo- to the required level of precision using standard geneous magnetic ¯eld of 1.7 T [3]. Microwave theory. Precision experiments in M can provide transitions between the two energetically highest sensitive tests of the Standard Model of particle respectively two lowest Zeeman sublevels of the physics. Sensitive searches for new, yet unknown n=1 state at the frequencies º12 and º34 involve forces in nature become possible. Parameters in a muon spin flip. Due to parity violation in the speculative theories can be restricted. In partic- weak interaction muon decay process the e+ from ular, such speculations which try to expand the ¹+ decays are preferentially emitted in the ¹+ Standard Model in order to gain deeper insights spin direction. This allows a detection of the spin into some of its not well understood features, i.e. flips through a change in the spatial distribution where the standard theory gives well a full de- of the decay e+. The experiment has utilized the scription, but lacks a satisfactory explanation of technique of "Old Muonium", which allowed to the observed facts. In addition, fundamental con- reduce the line width of the signals below half of stants like the muon mass m¹, its magnetic mo- the "natural" line width ¢ºnat = 1=(2¼¿¹) [4], ment ¹¹ and magnetic anomaly a¹ and the ¯ne where ¿¹ = 2.2¹s is the muon lifetime. structure constant ® can be measured precisely The magnetic moment was measured to 120 by M spectroscopy. ppb, which translates into a muon-electron mass Recent precision experiments in M include ratio ¹¹=me of the same accuracy. The zero-¯eld spectroscopy of electromagnetic transitions in the hyper¯ne splitting is determined to 12 ppb and atom and a search for muonium-antimuonium agrees well with the theoretical prediction which (M-M) conversion. All these experiments involve is known to 120 ppb [5]. For the M hyper¯ne M atoms in the ground state where they can structure the comparison between theory and ex- be produced with highest e±ciency. The spec- periment is possible with almost two orders of 2 magnitude higher precision than for natural hy- electron mass ratio can be extracted from this to drogen because of the not su±ciently known pro- 0.8 ppm. Alternatively the measurement can be ton charge and magnetism distributions. The interpreted as a test of the charge quantization achieved { some six orders of magnitude higher in the ¯rst two lepton generations which results ¡9 { experimental precision in hydrogen maser ex- as qm+ =qe¡ + 1 = ¡1:1(2:1) ¢ 10 . This is the periments can unfortunately not be exploited for best veri¯cation of charge equality in the ¯rst two a better understanding of fundamental interac- generations. The existence of one single universal tions. Most of the corrections to the Fermi HFS unit of charge is solely an experimental fact. No splitting in M arise from QED. This allows for underlying symmetry could yet be identi¯ed. the most precise determination of the ¯ne struc- ture constant ® from a bound state. Among the 4. Muonium-Antimuonium Conversion non-QED contributions is the strong interaction through vacuum polarization loops with hadrons In addition to the indirect searches for signa- (56 ppb) and a parity conserving axial vector- tures of new physics in the muon magnetic anom- axial vector weak interaction (-14 ppb). aly and in electromagnetic interactions within the It should be noted that ¹¹ is an essential in- M atom the bound state o®ers also the possibility put into the muon g-2 measurement. Future g-2 to search more directly for predictions of specula- experiments might be limited by this quantity un- tive models. The process of (M-M) onversion vio- less some improved number will be determined in lates additive lepton family number conservation. a future high precision experiment. It would be an analogy to the well known K0-K0 Recently, generic extensions of the Standard and B0-B0 oscillations. M-M conversion appears Model, in which both Lorentz invariance and naturally in many theories beyond the Standard CPT invariance are not assumed, have attracted Model. The interaction could be mediated, e.g., widespread attention in physics. Diurnal varia- by a doubly charged Higgs boson ¢++, Majorana tions of the ratio (º12 ¡ º34)=(º12 + º34) are pre- neutrinos, a neutral scalar, a supersymmetric ¿- dicted. An upper limit could be set from a re- sneutrino, or a doubly charged bileptonic gauge analysis of the LAMPF data at 2 ¢ 10¡23 GeV for boson. the Lorentz and CPT violating parameter. In At PSI an experiment was designed to exploit a a speci¯c model by Kostelecky and co-workers powerful new signature, which requires the coin- a dimensionless ¯gure of merit for CPT tests is cident identi¯cation of both particles forming the sought by normalizing this parameter to the par- anti-atom in its decay [11]. Thermal M atoms ticle mass. In this framework ¢ºHFS provides a in vacuum from a SiO2 powder target, are ob- signi¯cantly better test of CPT invariance than served for decays. (Vacuum is indispensable, as in electron g-2 and the neutral Kaon oscillations[6]. a gas or in condensed matter the conversion would be signi¯cantly suppressed.) Energetic electrons ¡ 3. 1s-2s interval from the decay of the ¹ in the atom can be iden- ti¯ed in a magnetic spectrometer. The positron Doppler-free excitation of the 1s-2s transition in the atomic shell of M is left behind after the has been achieved in pioneering experiments at decay with 13.5 eV average kinetic energy. It KEK [7] and at RAL [8]. In all these experiments has been post-accelerated and guided in a mag- two counter-propagating pulsed laser beams at netic transport system onto a position sensitive 244 nm wavelength were employed to excite the micro-channel plate detector (MCP). Annihila- n=2 state. The successful transitions were then tion radiation can be observed in a segmented detected by photo-ionization with a third photon pure CsI calorimeter around it. The decay vertex from the same laser ¯eld through the released ¹+. can be reconstructed. The measurements were The RAL experiment [9] yields ¢º1s2s(exp) performed during a period of 6 months in total to 4 ppb in good agreement with a theoretical over 4 years during which 5:7¢1010 M atoms were value which is known to 0.6 ppb[10]. The muon- in the interaction region. One event fell within 3 a 99% con¯dence interval of all relevant distribu- source. There the 'Old Muonium' technique could tions. The expected background due to accidental be bene¯tially employed, because the conversion coincidences is 1.7(2) events. Depending on the progresses with time squared and beam related interaction details one has to account for a sup- background falls o® exponentially with time. pression of the conversion in the 0.1 T magnetic ¯eld in the spectrometer. This amounts maxi- REFERENCES mally to a factor of about 3 for V§A type inter- actions. The upper limit on the conversion prob- 1. V.W. Hughes and G. zu Putlitz, in: Quantum ability is 8:2 ¢ 10¡11 (90% C.L.). The coupling Electrodynamics, ed. T. Kinoshita (World Sci- constant is bound to below 3:0 ¢ 10¡3 G , where enti¯c, 1990) p. 822 F 2. K. Jungmann, nucl-ex/0404013 (2004) GF is the Fermi coupling constant. This new result, which exceeds limits from pre- 3. W. Liu et al., Phys.Rev.Lett.82, 711 (1999) vious experiments by a factor of 2500 and one 4. M.G. Boshier et al., Phys. Rev.A52, 1948 from an early stage of the experiment by 35, has (1995) some impact on speculative models. For exam- 5. M. Eides et al., Phys. Rev.D67,113003 (2003); S. Eidelman et al., Can. J. Phys.80, ple: A certain Z8 model is ruled out. It had more than 4 generations of particles and where masses 1297 (2002) could be generated radiatively with heavy lepton 6. V.W. Hughes et al., Phys.Rev.Lett.87, 2 111804 (2001); R. Bluhm et al., Phys. seeding. A new lower limit of 2.6 TeV/c £ g3l (95% C.L.) on the masses of flavour diagonal Rev.D 57 3932 (1998); R.
Load more

Recommended publications
  • 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.
    [Show full text]
  • 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].
    [Show full text]
  • Hadronic Light-By-Light Contribution to $(G-2) \Mu $ from Lattice QCD: A
    MITP/21-019 CERN-TH-2021-047 Hadronic light-by-light contribution to (g − 2)µ from lattice QCD: a complete calculation En-Hung Chao,1 Renwick J. Hudspith,1 Antoine G´erardin,2 Jeremy R. Green,3 Harvey B. Meyer,1, 4, 5 and Konstantin Ottnad1 1PRISMA+ Cluster of Excellence & Institut f¨urKernphysik, Johannes Gutenberg-Universit¨atMainz, D-55099 Mainz, Germany 2Aix Marseille Univ, Universit´ede Toulon, CNRS, CPT, Marseille, France 3Theoretical Physics Department, CERN, 1211 Geneva 23, Switzerland 4Helmholtz Institut Mainz, Staudingerweg 18, D-55128 Mainz, Germany 5GSI Helmholtzzentrum f¨urSchwerionenforschung, Darmstadt, Germany (Dated: April 7, 2021) We compute the hadronic light-by-light scattering contribution to the muon g 2 − from the up, down, and strange-quark sector directly using lattice QCD. Our calcu- lation features evaluations of all possible Wick-contractions of the relevant hadronic four-point function and incorporates several different pion masses, volumes, and lattice-spacings. We obtain a value of aHlbl = 106:8(14:7) 10−11 (adding statistical µ × and systematic errors in quadrature), which is consistent with current phenomenolog- ical estimates and a previous lattice determination. It now appears conclusive that the hadronic light-by-light contribution cannot explain the current tension between theory and experiment for the muon g 2. − I. INTRODUCTION The anomalous magnetic moment of the muon, aµ (g 2)µ=2, is one of the most precisely measured quantities of the Standard Model (SM)≡ of− particle physics. Its value is of considerable interest to the physics community as, currently, there exists a 3:7σ tension between the experimental determination of Ref.
    [Show full text]
  • Angular Distribution Measurement of Beam-Foil Muonium Part II: Muon Injection Simulation for a New Muon G-2 Experiment
    LAr-12380-T DE93 002178 Part I: Angular Distribution Measurement of Beam-Foil Muonium Part II: Muon Injection Simulation for a New Muon g-2 Experiment Hyo Eun Ahn* 'Guest Scientist at Los Alamos. Department of Physics, Yale University, New Haven, CT 06511-8167. DISTFUDUTiCN Of-' TH5S DOCUMENT 16 f7\\C^ /A\ fl^ir?Trr)/?^i(^ Los A|amos National Laboratoryy L ^© ZAiUaiLI LJ U\VJ& LoL s Alamos.NeAlN w MexicMi o 8754875455 Acknowledgement s I thank my advisor, Vernon Hughes, for his support and guidance throughout the last five years and for providing me an opportunity to work on both muonium experiments at LAMPF and the simulation study on muon g—2 experiment at BNL. I am grateful to Walter Lysenko for introducing me to the simulation study of muon injection and the availability of his help whenever I need. I also like to thank my collaborators for the angular distribution experiment. They are Frank Chmely, Ver- non Hughes, Steve Kittell, Yunan Kuang, Bjorn Matthias, Hans-Jurgen Mundinger, Benwen Ni, Gisbert zu Putlitz, Reiner Schaefer, and Kim Woodle. This experiment would not have been possible without the effort and commitment of these co-workers. Special thanks goes to Bjorn Matthias ior many helpful remarks and discussion from the first stage of data analysis to reading this manuscript. Technical support from LAMPF staff was marvelous. Thanks goes to Jov Ivie, Chandra Pillai, Richard Werbeck, and the LAMPF staff. I appreciate the help of the staff at the data analysis center (DAC) of LAMPF; they are Art Chavez, John Faucett, Elvira Martinez, and Mike Oothoudt.
    [Show full text]
  • Experimental Limits for the Electron-Proton Charge Difference and for the Neutron Charge
    790 Session P 1 (II and III) polarized muons were stopped in argon Our recent measurements of the asymmetry para­ at different magnetic fields and for case I pions were meter, a, for various gases at high pressure, done in stopped. The solid curves were obtained from the a free muon precession experiment3), give : analysis of the data and represent the per cent am­ plitude of A compared to the total counting rate. The dashed curves are theoretical line shapes centered in each case at the muonium precession frequency predicted from the measured value of the magnetic field. Resonances are clearly seen in cases II and Since depolarization in this experiment is a necessary III and indicate abundant formation of muonium condition for muonium formation, it can be conclu­ in pure argon. ded that no more than one half of the muons stopping The general conditions required to form muonium in SF6 and 02 form muonium, whereas all of the and to retain its polarization are not well understood. muons may form muonium in A, N2, and N20. From our experiments alone it is not determined In view of the abundant formation of muonium in whether the high purity of the argon gas is required, pure argon, it should be possible to measure the although if they are combined with unpublished hyperfine structure, Av, of muonium with high preci­ negative results of others2) it appears that the purity sion. Comparison of a precise experimental value is essential. If this is indeed true, it seems quite for Av with the theoretical value would provide a likely that free muonium is lost in a chemical reac­ critical test of electrodynamics involving the muon tion in impure argon.
    [Show full text]
  • Physics of Muonium and Muonium Oscillations
    Physics of muonium and muonium oscillations Alexey A. Petrov1 1Department of Physics and Astronomy Wayne State University, Detroit, MI 48201, USA Precision studies of a muonium, the bound state of a muon and an electron, provide access to physics beyond the Standard Model. We propose that extensive theoretical and experimental studies of atomic physics of a muonium, its decays and muonium-antimuonium oscillations could provide an impact on indirect searches for new physics. An especially clean system to study BSM effects in in the Standard Model at tree level, New Physics degrees lepton sector is muonium Mµ, a QED bound state of a of freedom can effectively compete with the SM parti- positively-charged muon and a negatively-charged elec- cles running in the loop graphs, making their discovery + − tron, jMµi ≡ jµ e i. The main decay channel of the possible. This is, of course, only true provided beyond state is driven by the weak decay of the muon. The av- the Standard Model (BSM) constructions include flavor- erage lifetime of a muonium state τMµ is thus expected violating interactions. In order to probe those we con- to be the same as that of the muon, τµ = (2:1969811 ± sider muonium decays and oscillations. −6 0:0000022) × 10 s [1], apart from the tiny effect due to Denoting the \muon quantum number" by Lµ, FCNC 2 2 2 −10 time dilation, (τMµ −τµ)/τµ = α me=(2mµ) = 6×10 . decays of a muonium would probe ∆Lµ = 1 interactions. Such a lifetime, in principle, is rather long to allow for The effective Lagrangian, L∆Lµ=1, can then be divided precision measurements of muonium's atomic and parti- eff into the dipole part, LD, and a part that involves four- cle physics properties [2].
    [Show full text]
  • RCED-85-96 DOE's Physics Accelerators
    DOE’s Physics Accelerators: Their Costs And Benefits This report provides an inventory of the Department of Energy’s existing and planned high-energy physics and nuclear physics accelerator facilities, identifies their as- sociated costs, and presents information on the benefits being derived from their construction and operation. These facilities are the primary tools used by high-energy and nuclear physicists to learn more about what energy and matter consist of and how their component parts or particles are influenced by the most basic natural forces. Of DOE’s $728 million budget for high-energy physics and nuclear physics during fiscal year 1985, about $372.1 million is earmarked for operating 14 DOE-supported accelerator facilities coast-to-coast. DOE’s investment in these facilities amounts to about $1.2 billion. If DOE’s current plans for adding new facilities are carried out, this investment could grow by about $4.3 billion through fiscal year 1994. Annual facility operating costs wilt also grow by about $230 million, or an increase of about 60 percent over current costs. The primary benefits gained from DOE’s investment in these facilities are new scientific knowledge and the education and training of future physicists. Accor- ding to DOE and accelerator facility officials, accelerator particle beams are also used in other scientific applications and have some medical and industrial applications. GAOIRCED-85-96 B APRIL 1,198s 031763 UNITED STATES GENERAL ACCOUNTING OFFICE WASHINGTON, D.C. 20548 RESOURCES, COMMUNlfY, \ND ECONOMIC DEVELOPMENT DIV ISlON B-217863 The Honorable J. Bennett Johnston Ranking Minority Member Subcommittee on Energy and Water Development Committee on Appropriations United States Senate Dear Senator Johnston: This report responds to your request dated November 25, 1984.
    [Show full text]
  • Study of Nuclear Properties with Muonic Atoms
    EPJ manuscript No. (will be inserted by the editor) Study of nuclear properties with muonic atoms A. Knecht1a, A. Skawran1;2b, and S. M. Vogiatzi1;2c 1 Paul Scherrer Institut, Villigen, Switzerland 2 Institut f¨urTeilchen- und Astrophysik, ETH Z¨urich, Switzerland Received: date / Revised version: date Abstract. Muons are a fascinating probe to study nuclear properties. Muonic atoms can easily be formed by stopping negative muons inside a material. The muon is subsequently captured by the nucleus and, due to its much higher mass compared to the electron, orbits the nucleus at very small distances. During this atomic capture process the muon emits characteristic X-rays during its cascade down to the ground state. The energies of these X-rays reveal the muonic energy level scheme, from which properties like the nuclear charge radius or its quadrupole moment can be extracted. While almost all stable elements have been examined using muons, probing highly radioactive atoms has so far not been possible. The muX experiment has developed a technique based on transfer reaction inside a high pressure hydrogen/deuterium gas cell to examine targets available only in microgram quantities. PACS. 14.60. Ef Muons { 36.10.Dr Positronium, muonium, muonic atoms and molecules { 32.30.Rj X-ray spectra { 21.10.-k General and average properties of nuclei 1 Introduction Muons are fascinating particles with experiments being conducted in the context of particle, nuclear and atomic physics [1]. Additionally, also applied research is possible by measuring the spin precession and dynamics of muons inside materials through the µSR technique [2] thus probing the internal magnetic fields of the sample under study.
    [Show full text]
  • The Nuclear Physics of Muon Capture
    Physics Reports 354 (2001) 243–409 The nuclear physics of muon capture D.F. Measday ∗ University of British Columbia, 6224 Agricultural Rd., Vancouver, BC, Canada V6T 1Z1 Received December 2000; editor: G:E: Brown Contents 4.8. Charged particles 330 4.9. Fission 335 1. Introduction 245 5. -ray studies 343 1.1. Prologue 245 5.1. Introduction 343 1.2. General introduction 245 5.2. Silicon-28 350 1.3. Previous reviews 247 5.3. Lithium, beryllium and boron 360 2. Fundamental concepts 248 5.4. Carbon, nitrogen and oxygen 363 2.1. Properties of the muon and neutrino 248 5.5. Fluorine and neon 372 2.2. Weak interactions 253 5.6. Sodium, magnesium, aluminium, 372 3. Muonic atom 264 phosphorus 3.1. Atomic capture 264 5.7. Sulphur, chlorine, and potassium 377 3.2. Muonic cascade 269 5.8. Calcium 379 3.3. Hyperÿne transition 275 5.9. Heavy elements 383 4. Muon capture in nuclei 281 6. Other topics 387 4.1. Hydrogen 282 6.1. Radiative muon capture 387 4.2. Deuterium and tritium 284 6.2. Summary of g determinations 391 4.3. Helium-3 290 P 6.3. The (; e±) reaction 393 4.4. Helium-4 294 7. Summary 395 4.5. Total capture rate 294 Acknowledgements 396 4.6. General features in nuclei 300 References 397 4.7. Neutron production 311 ∗ Tel.: +1-604-822-5098; fax: +1-604-822-5098. E-mail address: [email protected] (D.F. Measday). 0370-1573/01/$ - see front matter c 2001 Published by Elsevier Science B.V.
    [Show full text]
  • ELEMENTARY PARTICLES in PHYSICS 1 Elementary Particles in Physics S
    ELEMENTARY PARTICLES IN PHYSICS 1 Elementary Particles in Physics S. Gasiorowicz and P. Langacker Elementary-particle physics deals with the fundamental constituents of mat- ter and their interactions. In the past several decades an enormous amount of experimental information has been accumulated, and many patterns and sys- tematic features have been observed. Highly successful mathematical theories of the electromagnetic, weak, and strong interactions have been devised and tested. These theories, which are collectively known as the standard model, are almost certainly the correct description of Nature, to first approximation, down to a distance scale 1/1000th the size of the atomic nucleus. There are also spec- ulative but encouraging developments in the attempt to unify these interactions into a simple underlying framework, and even to incorporate quantum gravity in a parameter-free “theory of everything.” In this article we shall attempt to highlight the ways in which information has been organized, and to sketch the outlines of the standard model and its possible extensions. Classification of Particles The particles that have been identified in high-energy experiments fall into dis- tinct classes. There are the leptons (see Electron, Leptons, Neutrino, Muonium), 1 all of which have spin 2 . They may be charged or neutral. The charged lep- tons have electromagnetic as well as weak interactions; the neutral ones only interact weakly. There are three well-defined lepton pairs, the electron (e−) and − the electron neutrino (νe), the muon (µ ) and the muon neutrino (νµ), and the (much heavier) charged lepton, the tau (τ), and its tau neutrino (ντ ). These particles all have antiparticles, in accordance with the predictions of relativistic quantum mechanics (see CPT Theorem).
    [Show full text]
  • Positronium and Muonium Two Photon Laser Spectroscopy
    Positronium and Muonium two photon laser spectroscopy Paolo Crivelli Institute for Particle Physics and Astrophysics, ETH Zurich LEAP 2018- 16th of March 2018 – Paris (France) Leptonic atoms PrecisePrecise test test of of FundamentalFundamental boundbound state state QED QED freefree from from finite finite size size effects effects constantsconstants PositroniumPositronium (Ps) (Ps) MuoniumMuonium (Mu) (Mu) ee- - ee+ + TestTest of of the the fundamental fundamental TestTest the the effect effect of of gravity gravity symmetriessymmetries and and search search onon forfor new new physics physics anti-matteranti-matter See talks Vargas and Moskal See talk A. Soter ApplicationsApplications in in material material TODAY: arXiv:1803.05744 [hep-ex] sciencescience Ps/Mu energy levels Ps Energy levels Mu Energy levels n n 4 4 3S 3P 3D 3S 3P 3D 3 3 3 2 S 1.1 s 2P 3.2 ns 2S 2.2 s 2P 1.6 ns 2 1 2 2 photons transition: 2 photons transition: =486 nm =244 nm Natural linewidth: Natural linewidth: 1.2 MHz 144 kHz 3S 142 ns 1S 2.2 s 1 1 1 Positronium 1S-2S transition S. G. Karshenboim, Phys. Rep. 422, 1 (2005) Theory: νtheory=1233607222.2(6 ) MHz K. Pachucki and S. G. Karshenboim, Phys. Rev. A60, 2792 (1999), K. Melnikov and A. Yelkhovsky, Phys. Lett. B458, 143 (1999)¨. Adkins, Kim, Parsons and Fell, PRL 115 233401 (2015) Experiments: νa=1233607216 .4 (3.2 ) MHz M. S. Fee et al., Phys. Rev. Lett. 70, 1397 (1993) S. Chu, A. P. Mills, Jr. and J. Hall, Phys. Rev. Lett. 52,1689 (1984) New measurement ongoing at ETHZ: goal 0.5 MHz 1) Check QED calculations (7m) 2) Stringent test of SME See talk A.Vargas 3) Positron to electron mass ratio Paolo Crivelli Muonium 1S-2S spectroscopy Experiment: Meyer et al.
    [Show full text]
  • Muonium-Antimuonium Oscillations in Effective Field Theory
    PHYSICAL REVIEW D 102, 095001 (2020) Muonium-antimuonium oscillations in effective field theory Renae Conlin 1 and Alexey A. Petrov 1,2 1Department of Physics and Astronomy Wayne State University, Detroit, Michigan 48201, USA 2Leinweber Center for Theoretical Physics University of Michigan, Ann Arbor, Michigan 48196, USA (Received 3 June 2020; accepted 9 October 2020; published 3 November 2020) Flavor violating processes in the lepton sector have highly suppressed branching ratios in the standard model, mainly due to the tiny neutrino mass. This means that observing a lepton flavor violation (LFV) in the next round of experiments would constitute a clear indication of physics beyond the standard model (BSM). We revisit a discussion of one possible way to search for LFV, muonium-antimuonium oscillations. This process violates the muon lepton number by two units and could be sensitive to the types of BSM physics that are not probed by other types of LFV processes. Using techniques of effective field theory, we calculate the mass and width differences of the mass eigenstates of muonium. We argue that its invisible decays give the parametrically leading contribution to the lifetime difference and put constraints on the scales of new physics probed by effective operators in muonium oscillations. DOI: 10.1103/PhysRevD.102.095001 I. INTRODUCTION So far, we have not yet observed FCNC in the charged Flavor-changing neutral current (FCNC) interactions lepton sector. This is because in the standard model with serve as a powerful probe of physics beyond the standard massive neutrinos, the charged lepton flavor violating (CLFV) transitions are suppressed by the powers of model (BSM).
    [Show full text]