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People and Things
Physics monitor People and things Books received CERN Council Bookshelf At the meeting of CERN's governing Future High Energy Colliders, Editor body, Council, in December, Luciano Weak Neutral Currents - The Zohreh Parsa, AIP Conference Maiani was elected the next Director Discovery of the Electro-Weak Force, Proceedings 397, ISBN 1-56396- General of the Organization, to take edited by David B. Cline, Addison 729-4 office on 1 January 1999, when the Wesley (Frontiers of Physics Series), current Director General, Chris ISBN 0-201-93347-0 Llewellyn Smith, will have completed Proceedings of a meeting held in his five year mandate. A Addison Wesley's Frontiers of Santa Barbara in October 1996 (see distinguished theorist, Luciano Physics Series began in 1961, and March 1997 issue of the CERN Maiani is currently President of the David Cline's anthology on weak Courier, page 16). Italian INFN and has been President neutral currents is the 97th volume in of CERN Council since January the series. 'Frontiers' books usually 1997. make extensive use of lecture notes The Interpretation of Quantum At the same meeting, leading or reprints, and Cline's volume takes Mechanics and the Measurement German science administrator and the latter route. It is divided into 9 Process, by Peter Mittelstaedt, head of Germany's CERN delegation chapters: The Weak Interaction Cambridge University Press 0 521 Hans C. Eschelbacher was elected Uncovered; Forty Years of Weak 55445 4 £30/$44.95 President of CERN Council for an Interactions; The Search for Other initial period of one year from 1 Forms of Weak Interaction; The January 1998, replacing Luciano Electroweak Interaction Picture A volume of interest to the more Maiani. -
New Insights to Old Problems
New Insights to Old Problems∗ T. D. Lee Pupin Physics Laboratory, Columbia University, New York, NY, USA and China Center of Advanced Science and Technology (CCAST), Beijing, China Abstract From the history of the θ-τ puzzle and the discovery of parity non-conservation in 1956, we review the current status of discrete symmetry violations in the weak interaction. Possible origin of these symmetry violations are discussed. PACS: 11.30.Er, 12.15.Ff, 14.60.Pq Key words: history of discovery of parity violation, mixing angles, origin of symmetry violation, scalar field and properties of vacuum arXiv:hep-ph/0605017v1 1 May 2006 ∗Based on an invited talk given at the 2006 APS Meeting as the first presentation in the Session on 50 Years Since the Discovery of Parity Nonconservation in the Weak Interaction I, April 22, 2006 (Appendix A) 1 1. Symmetry Violations: The Discovery Almost exactly 50 years ago, I had an important conversation with my dear friend and colleague C. S. Wu. This conversation was critical for setting in mo- tion the events that led to the experimental discovery of parity nonconservation in β-decay by Wu, et al.[1]. In the words of C. S. Wu[2]: ”· · · One day in the early Spring of 1956, Professor T. D. Lee came up to my little office on the thirteenth floor of Pupin Physical Laboratories. He explained to me, first, the τ-θ puzzle. If the answer to the τ-θ puzzle is violation of parity–he went on–then the violation should also be observed in the space distribution of the beta-decay of polarized nuclei: one must measure the pseudo-scalar quantity <σ · p > where p is the electron momentum and σ the spin of the nucleus. -
The Standard Model Part II: Charged Current Weak Interactions I
Prepared for submission to JHEP The Standard Model Part II: Charged Current weak interactions I Keith Hamiltona aDepartment of Physics and Astronomy, University College London, London, WC1E 6BT, UK E-mail: [email protected] Abstract: Rough notes on ... Introduction • Relation between G and g • F W Leptonic CC processes, ⌫e− scattering • Estimated time: 3 hours ⇠ Contents 1 Charged current weak interactions 1 1.1 Introduction 1 1.2 Leptonic charge current process 9 1 Charged current weak interactions 1.1 Introduction Back in the early 1930’s we physicists were puzzled by nuclear decay. • – In particular, the nucleus was observed to decay into a nucleus with the same mass number (A A) and one atomic number higher (Z Z + 1), and an emitted electron. ! ! – In such a two-body decay the energy of the electron in the decay rest frame is constrained by energy-momentum conservation alone to have a unique value. – However, it was observed to have a continuous range of values. In 1930 Pauli first introduced the neutrino as a way to explain the observed continuous energy • spectrum of the electron emitted in nuclear beta decay – Pauli was proposing that the decay was not two-body but three-body and that one of the three decay products was simply able to evade detection. To satisfy the history police • – We point out that when Pauli first proposed this mechanism the neutron had not yet been discovered and so Pauli had in fact named the third mystery particle a ‘neutron’. – The neutron was discovered two years later by Chadwick (for which he was awarded the Nobel Prize shortly afterwards in 1935). -
A Tribute to Bj0rn Wiik General Distribution: Jacques Dallemagne, CERN, 1211 Geneva 23, Switzerland
W M£W HSmzS OF THS p\J\Q fAMM WQ 722S: w PCI mmm FOR w - FOR. SUN, HP, b£C, MMs, Direct single shot and DMA transfers On-board PCI MMU On-board PCI chained DMA controller Generic C library and drivers for Windows NT, MacOS, SOLARIS, Digital UNIX, HPUX, LINUX PWC ?02S: Tf/e FUNCTION COMMWE zeptAcenem FOR W VIC ?2S0 / 22S7 VME transparent mapping in the PCI memory space VME transparent slot 1 and arbiter Full VME master / slave Support D&, D16, D32, D64, direct transfers On-board VME linked list DMA controller The CES-f3Pnet (CES backplane Driver Network) offers an efficient interprocessor communication and synchronization mechanism, combining microsecond-level resolution and network-oriented services over the PVIC. The CES-l3Pnet offers three types of services to ensure efficient communications between CES processors: • An extension of the POSIX inter processes communication (shared memory semaphores - message queues) • An efficient and straightforward message passing system • A full TCF/IF stack using the PVIC as a network device W CjPtO: fi USeZ-PZOQMMMm Q6N6RAL PUZPK6 f/WT / OlUM PHC Stepper motor Controller Timer and counter 32-bit Input / Outputs (TTL or DIFF) Multiple lines PS 455 / PS 232 / PS 422 . Up to 6 GPIOs connected on a single PI02 with PMC carrier boards extension SOFTWARE C\6F Programming Kit for FPGA equations LynxOS and VxWorks drivers for PI02 family CES Geneva, Switzerland Tel: +41-22 792 57 45 Fax: +41-22 792 57 4d EMail: ces^ces.ch CES.D Germany Tel: +49-60 51 96 97 4 ' Fax: +49-60 51 96 97 35 CE6 Creative Electronic Systems 5A, 70 Route du Pont-3utin, CH-1213 Petit-Lancy 1, Switzerland Internet: http://www.ces.ch CREATIVE ELECTRONIC SYSTEMS CONTENTS Covering current developments in high- energy physics and related fields worldwide CERN Courier is distributed to Member State governments, institutes and laboratories affiliated with CERN, and to their personnel. -
XIII Probing the Weak Interaction
XIII Probing the weak interaction 1) Phenomenology of weak decays 2) Parity violation and neutrino helicity (Wu experiment and Goldhaber experiment) 3) V- A theory 4) Structure of neutral currents Parity → eigenvalues of parity are +1 (even parity), -1 (odd parity) Parity is conserved in strong and electromagnetic interactions Parity and momentum operator do not commute! Therefore intrinsic partiy is (strictly speaken) defined only for particles AT REST If a system of two particles has a relative angular momentum L, total parity is given by: (*) where are the intrinsic parity of particles Parity is a multiplicative quantum number Parity of spin + ½ fermions (quarks, leptons) per definition P = +1 Parity of spin - ½ anti-fermions (anti-quarks, anti-leptons) P = -1 Parity of W, Z, photon, gluons (and their antiparticles) P =-1 (result of gauge theory) (strictly speaken parity of photon and gluons are not defined, use definition of field) For all other composed and excited particles e.g. kaon, proton, pion, use rule (*) and/or parity conserving IA to determine intrinsic parity Reminder: Parity operator: Intrinsic parity of spin ½ fermions AT REST: +1; of antiparticles: -1 Wu-Experiment Idea: Measurement of the angular distribution of the emitted electron in the decay of polarized 60Co nulcei Angular momentum is an axial vector P J=5 J=4 If P is conserved, the angular distribution must be symmetric (to the dashed line) Identical rates for and . Experiment: Invert 60Co polarization and compare the rates under the same angle . photons are preferably emitted in direction of spin of Ni → test polarization of 60Co (elm. -
Scientific and Related Works of Chen Ning Yang
Scientific and Related Works of Chen Ning Yang [42a] C. N. Yang. Group Theory and the Vibration of Polyatomic Molecules. B.Sc. thesis, National Southwest Associated University (1942). [44a] C. N. Yang. On the Uniqueness of Young's Differentials. Bull. Amer. Math. Soc. 50, 373 (1944). [44b] C. N. Yang. Variation of Interaction Energy with Change of Lattice Constants and Change of Degree of Order. Chinese J. of Phys. 5, 138 (1944). [44c] C. N. Yang. Investigations in the Statistical Theory of Superlattices. M.Sc. thesis, National Tsing Hua University (1944). [45a] C. N. Yang. A Generalization of the Quasi-Chemical Method in the Statistical Theory of Superlattices. J. Chem. Phys. 13, 66 (1945). [45b] C. N. Yang. The Critical Temperature and Discontinuity of Specific Heat of a Superlattice. Chinese J. Phys. 6, 59 (1945). [46a] James Alexander, Geoffrey Chew, Walter Salove, Chen Yang. Translation of the 1933 Pauli article in Handbuch der Physik, volume 14, Part II; Chapter 2, Section B. [47a] C. N. Yang. On Quantized Space-Time. Phys. Rev. 72, 874 (1947). [47b] C. N. Yang and Y. Y. Li. General Theory of the Quasi-Chemical Method in the Statistical Theory of Superlattices. Chinese J. Phys. 7, 59 (1947). [48a] C. N. Yang. On the Angular Distribution in Nuclear Reactions and Coincidence Measurements. Phys. Rev. 74, 764 (1948). 2 [48b] S. K. Allison, H. V. Argo, W. R. Arnold, L. del Rosario, H. A. Wilcox and C. N. Yang. Measurement of Short Range Nuclear Recoils from Disintegrations of the Light Elements. Phys. Rev. 74, 1233 (1948). [48c] C. -
Evidence for a Sublattice Weak Gravity Conjecture
Evidence for a Sublattice Weak Gravity Conjecture The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Heidenreich, Ben, Matthew Reece, and Tom Rudelius. 2017. Evidence for a Sublattice Weak Gravity Conjecture. Journal of High Energy Physics 2017, 25. Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:41392811 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Open Access Policy Articles, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#OAP Prepared for submission to JHEP Evidence for a Sublattice Weak Gravity Conjecture Ben Heidenreich,a;b Matthew Reece,a and Tom Rudeliusa aDepartment of Physics, Harvard University, Cambridge, MA 02138, USA bPerimeter Institute for Theoretical Physics, Waterloo, Ontario, Canada N2L 2Y5 E-mail: [email protected], [email protected], [email protected] Abstract: The Weak Gravity Conjecture postulates the existence of superextremal charged particles, i.e. those with mass smaller than or equal to their charge in Planck units. We present further evidence for our recent observation that in known examples a much stronger statement is true: an infinite tower of superextremal particles of different charges exists. We show that effective Kaluza-Klein field theories and perturbative string vacua respect the Sublattice Weak Gravity Conjecture, namely that a finite index sublattice of the full charge lattice exists with a superextremal particle at each site. In perturbative string theory we show that this follows from modular invariance. -
Reversal of the Parity Conservation Law in Nuclear Physics
Reversal of the Parity Conservation Law in Nuclear Physics In late 1956, experiments at the National Bureau of proton with an atomic nucleus. The K meson seemed to Standards demonstrated that the quantum mechanical arise in two distinct versions, one decaying into two law of conservation of parity does not hold in the beta mesons, the other decaying into three pions, with the decay of 60Co nuclei. This result, reported in the paper two versions being identical in all other characteristics. An experimental test of parity conservation in beta A mathematical analysis showed that the two-pion and decay [1], together with ensuing experiments on parity the three-pion systems have opposite parity; hence, conservation in -meson decay at Columbia University, according to the prevalent theory, these two versions of shattered a fundamental concept of nuclear physics that the K meson had to be different particles. had been universally accepted for the previous 30 years. Early in 1956, T. D. Lee of Columbia University It thus cleared the way for a reconsideration of physical and C. N. Yang of the Institute for Advanced Study, theories, especially those relating to symmetry, and led Princeton University, made a survey [4] of experimental to new, far-reaching discoveries regarding the nature information on the question of parity. They concluded of matter and the universe. In particular, removal of that the evidence then existing neither supported nor the restrictions imposed by parity conservation first refuted parity conservation in the “weak interactions” resolved a serious conflict in the theory of subatomic responsible for the emission of beta particles, K-meson particles, known at the time as the tau-theta puzzle, and decay, and such. -
A Brief Introduction to the Weak Gravity Conjecture Eran Palti Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
Letters in High Energy Physics LHEP-176, 2020 A Brief Introduction to the Weak Gravity Conjecture Eran Palti Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel Abstract The Weak Gravity Conjecture proposes that a theory with a gauge field that is coupled to gravity must have charged matter on which gravity acts as the weakest force. It also proposes that there is an intrinsic cutoff on such an effective theory, which corresponds to a tower of charged states, that is set by the strength of the gauge coupling (in Planck units). This article is a brief introduction to the Weak Gravity Conjecture, covering aspects of the motivations for it as well as various extensions and refinements. Keywords: Swampland, Quantum Gravity, String Theory gauge fields for simplicity), with gauge coupling g, there must DOI: 10.31526/LHEP.2020.176 exist at least one particle with quantized charge q and mass m which satisfies the bound p 1. INTRODUCTION m ≤ 2gqMp . (4) There are four known forces in the universe: the strong and The bound (4) is termed the Electric WGC. This is to dif- weak forces, electromagnetism, and gravity. The known fun- ferentiate it from a related bound termed the Magnetic WGC. damental matter particles are all charged under at least two The simplest way to introduce this second bound is through the of these forces. For example, the right-handed electron carries electromagnetic dual of (4) [1]. Under electromagnetic duality electromagnetic charge and gravitational charge. These charges the gauge coupling g is exchanged for its inverse g−1, while the can be deduced from the Coulomb forces that two electrons feel electrically charged particle is exchanged for a monopole with when placed a distance r apart. -
Brief Newsletter from World Scientific February 2017
Brief Newsletter from World Scientific February 2017 Exclusive Interview with 2003 Nobel Laureate One of the Top Condensed Matter Theorists and World Scientific Author Anthony Leggett Sir Professor Anthony James Leggett is a distinguished physicist who was awarded the Nobel Prize in Physics in 2003 for his pioneering contributions to the theory of superconductors and superfluids. He is currently a professor at the University of Illinois at Urbana-Champaign. Prof Leggett gave a presentation at the 2016 APS March Meeting in Baltimore, USA on “Reflections on the past, present and future of condensed matter physics”. In a phone interview, he shared with us some of his thoughts and further musings on the future of condensed matter physics. Paradigm Shift and Our Quest for the Unknown Chad Hollingsworth Your talk at the APS March Meeting 2016 mentioned developments That probably depends on your current tenure status! Certainly, if that you classified as “paradigm shifts”. Are there any recent you have a secure, tenured job (as I have been fortunate enough to discoveries that you would classify as paradigm shifts? have for the last few decades), then I think most certainly it’s better Well, if we go slightly outside the area of condensed matter physics to explore the unknown. But, of course, I appreciate that in the current as it has been conventionally defined, then, undoubtedly, any employment situation, people who have not got a tenured job need revolution which overthrew the view of quantum mechanics as a to think about their future. This may well be a rather strong pressure complete account of the world would, I think, certainly qualify as a to basically explore the known further. -
Compositeness of Quarks and Leptons
COMPOSITENESS OF QUARKS AND LEPTONS Michael E. Peskin Laboratory of Nuclear Studies Cornell University Ithaca, New York, U.S.A. Introduction The theoretical talks we have heard so far at this symposium have been full of precision and technical detail in explaining the consequences of the gauge theories of the strong, weak, and electromagnetic interactions. The level of confusion and far-reaching speculation has been remarkably less than at previous conferences in this series, in great part because our current theories seem to be both fundamental and in good accord with experimental data. One might wish to believe that the study of fundamental physics is almost complete. Is it true, at least, that the quarks, leptons, and gauge bosons that we now observe are among the most basic building-blocks of Nature? Despite the temptation to agree, a stream of theoretical papers - a stream which has, in the past year, become a torrent - has argued that they are not. I have been as~ed to review this set of theoretical ideas. My review will necessarily ;~ contain more than its proper share of speculation and guesswork. But I hope to ',' make clear both the current status and the consequences of the idea that the quarks and leptons are composite, that another level of fundamental physics lies waiting to be discovered. There is, at the moment, no experimental evidence which would require the compositeness of quarks and leptons. Indeed, the simplicity of their gauge interactions makes quarks and leptons look convincingly elementary. What, then, encourages physicists to take the notion of their cornpositeness seriously? Three reasons come to mind. -
Arxiv:Quant-Ph/0101077 V1 17 Jan 2001 His Get When Rect W Y B Mals.” Cup of Ab of Miliar
100 Years of the Quantum Max Tegmark Dept. of Physics, Univ. of Pennsylvania, Philadelphia, PA 19104; [email protected] John Archibald Wheeler Princeton University, Department of Physics, Princeton, NJ 08544; [email protected] (An abbreviated version of this article, with much better graphics, was published in the Feb. 2001 issue of Scientific American, p.68-75.) Abstract: As quantum theory celebrates its 100th birthday, spectacular successes are mixed with outstanding puzzles and promises of new technologies. This article reviews both the successes of quantum theory and the ongoing debate about its consequences for issues ranging from quantum computation to consciousness, parallel universes and the nature of physical reality. We argue that modern experiments and the discovery of decoherence have have shifted prevailing quantum inter- pretations away from wave function collapse towards unitary physics, and discuss quantum processes in the framework of a tripartite subject-object-environment decomposition. We conclude with some speculations on the bigger picture and the search for a unified theory of quantum gravity. \...in a few years, all the great physical constants will ever, this involved an assumption so bizarre that even have been approximately estimated, and [...] the only oc- he distanced himself from it for many years afterwards: cupation which will then be left to the men of science will that energy was only emitted in certain finite chunks, or be to carry these measurement to another place of deci- \quanta". Yet this strange assumption proved extremely mals." As we enter the 21st century amid much brouhaha successful. Inspired by Planck's quantum hypothesis, Pe- about past achievements, this sentiment may sound fa- ter Debye showed that the strange thermal behavior of miliar.