Jul/Aug 2019 Edition
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
CERN Courier–Digital Edition
CERNMarch/April 2021 cerncourier.com COURIERReporting on international high-energy physics WELCOME CERN Courier – digital edition Welcome to the digital edition of the March/April 2021 issue of CERN Courier. Hadron colliders have contributed to a golden era of discovery in high-energy physics, hosting experiments that have enabled physicists to unearth the cornerstones of the Standard Model. This success story began 50 years ago with CERN’s Intersecting Storage Rings (featured on the cover of this issue) and culminated in the Large Hadron Collider (p38) – which has spawned thousands of papers in its first 10 years of operations alone (p47). It also bodes well for a potential future circular collider at CERN operating at a centre-of-mass energy of at least 100 TeV, a feasibility study for which is now in full swing. Even hadron colliders have their limits, however. To explore possible new physics at the highest energy scales, physicists are mounting a series of experiments to search for very weakly interacting “slim” particles that arise from extensions in the Standard Model (p25). Also celebrating a golden anniversary this year is the Institute for Nuclear Research in Moscow (p33), while, elsewhere in this issue: quantum sensors HADRON COLLIDERS target gravitational waves (p10); X-rays go behind the scenes of supernova 50 years of discovery 1987A (p12); a high-performance computing collaboration forms to handle the big-physics data onslaught (p22); Steven Weinberg talks about his latest work (p51); and much more. To sign up to the new-issue alert, please visit: http://comms.iop.org/k/iop/cerncourier To subscribe to the magazine, please visit: https://cerncourier.com/p/about-cern-courier EDITOR: MATTHEW CHALMERS, CERN DIGITAL EDITION CREATED BY IOP PUBLISHING ATLAS spots rare Higgs decay Weinberg on effective field theory Hunting for WISPs CCMarApr21_Cover_v1.indd 1 12/02/2021 09:24 CERNCOURIER www. -
People and Things
People and things On 15 April, Haim Harari of the Weizmann Institute, Israel, was guest speaker at a symposium to mark 20 years of accelerator operation at the Paul Scherrer Institute, Maurice Jacob's roving camera caught Murray Villigen, Switzerland. Gell Mann in a London pub with the manu (Photo Armin Muller) script of his book 'The Quark and the Jaguar'. 20 years of PSI In April the Swiss Paul Scherrer Institute celebrated 20 years of accelerator operations. Originally built for particle research, these facilities now extend over a wide spectrum of applications, from molecular structure to cancer therapy. Each year over 400 visiting researchers make use of PSI particle beams. Meetings An international symposium on strangeness and quark matter will be held from 1-5 September in Crete, covering 1. strangeness and quark- gluon plasma, 2. strangeness con LAPP, Annecy, well known authority French Academy of Sciences densation, 3. strange astrophysics, 4. on non-Abelian gauge theories, and strangelets, 5. dedicated instrumen Michel Davier, long-time specialist in tation for strangeness and quark Among the new corresponding electron-positron collision physics matter. Information from the Secre members of the French Academy of and former Director of the Orsay tariat, University of Athens, Physics Sciences (Academie des Sciences Linear Accelerator Laboratory. Other Dept., Nuclear & Particle Physics de Paris) are Raymond Stora of new members are Alain Aspect, Division, Panepistimioupolis, Greece- 15771 Athens, tel. (30-1)7247502, 7243362, 7243143, fax (30- 1)7235089, email gvassils ©atlas, uoa.ariadne-t.gr At a special colloquium held at CERN on 20 April to mark Carlo Rubbia's 60th birthday and the tenth anniversary of his Nobel Prize award with Simon van der Meer, left to right - Canadian TRIUMF Laboratory Director and former UA1 co-spokesman Alan Astbury, LHC Project Director Lyn Evans, Carlo Rubbia, Director General Chris Llewellyn Smith, and former UA 1 co-spokesman John Dowel I. -
Jet Development in Leading Log QCD.Pdf
17 CALT-68-740 DoE RESEARCH AND DEVELOPMENT REPORT Jet Development in Leading Log QCD * by STEPHEN WOLFRAM California Institute of Technology, Pasadena. California 91125 ABSTRACT A simple picture of jet development in QCD is described. Various appli- cations are treated, including transverse spreading of jets, hadroproduced y* pT distributions, lepton energy spectra from heavy quark decays, soft parton multiplicities and hadron cluster formation. *Work supported in part by the U.S. Department of Energy under Contract No. DE-AC-03-79ER0068 and by a Feynman Fellowship. 18 According to QCD, high-energy e+- e annihilation into hadrons is initiated by the production from the decaying virtual photon of a quark and an antiquark, ,- +- each with invariant masses up to the c.m. energy vs in the original e e collision. The q and q then travel outwards radiating gluons which serve to spread their energy and color into a jet of finite angle. After a time ~ 1/IS, the rate of gluon emissions presumably decreases roughly inversely with time, except for the logarithmic rise associated with the effective coupling con 2 stant, (a (t) ~ l/log(t/A ), where It is the invariant mass of the radiating s . quark). Finally, when emissions have degraded the energies of the partons produced until their invariant masses fall below some critical ~ (probably c a few times h), the system of quarks and gluons begins to condense into the observed hadrons. The probability for a gluon to be emitted at times of 0(--)1 is small IS and may be est~mated from the leading terms of a perturbation series in a (s). -
Spring 1998, Vol
S T A N F O R D L I N E A R A CCELERATOR CENTER Spring 1998, Vol. 28, No.1 A PERIODICAL OF PARTICLE PHYSICS SPRING 1998 VOL. 28, N UMBER 1 Editors RENE DONALDSON, BILL KIRK Contributing Editors MICHAEL RIORDAN, GORDON FRASER JUDY JACKSON, PEDRO WALOSCHEK Editorial Advisory Board GEORGE BROWN, LANCE DIXON JOEL PRIMACK, NATALIE ROE ROBERT SIEMANN, GEORGE TRILLING KARL VAN BIBBER Illustrations TERRY A NDERSON Distribution Lake CRYSTAL TILGHMAN Soudan Superior Duluth The Beam Line is published quarterly by the MN Lake Stanford Linear Accelerator Center WI Michigan PO Box 4349, Stanford, CA 94309. Telephone: (650) 926-2585 Madison INTERNET: [email protected] MI FAX: (650) 926-4500 IA Issues of the Beam Line are accessible electronically on the World Wide Web at http://www.slac.stanford.edu/ Fermilab pubs/beamline IL IN SLAC is operated by Stanford University under contract with the U.S. Department of Energy. The opinions of the authors do not necessarily reflect the policy of the MO Stanford Linear Accelerator Center. Cover:The cover photo was taken in 1917, plus or minus about one year. The photographer is unknown or unre- membered. The young lad shown in the photo with his telescope in the garden of his home in Pretoria, South Africa, is Alan Cousins, at the age of about fourteen (he was born in 1903). Dr. Cousins’ first contribution to the astronomical literature was published in 1924. Seventy-four years have passed since then, but Alan William James Cousins is still at work at his home base, the South African Astronomical Observatory (SAAO), having recently published his latest paper (“Atmospheric Extinc- tion,” The Observatory, April 1998). -
The Moedal Experiment at the LHC. Searching Beyond the Standard
126 EPJ Web of Conferences , 02024 (2016) DOI: 10.1051/epjconf/201612602024 ICNFP 2015 The MoEDAL experiment at the LHC Searching beyond the standard model James L. Pinfold (for the MoEDAL Collaboration)1,a 1 University of Alberta, Physics Department, Edmonton, Alberta T6G 0V1, Canada Abstract. MoEDAL is a pioneering experiment designed to search for highly ionizing avatars of new physics such as magnetic monopoles or massive (pseudo-)stable charged particles. Its groundbreaking physics program defines a number of scenarios that yield potentially revolutionary insights into such foundational questions as: are there extra dimensions or new symmetries; what is the mechanism for the generation of mass; does magnetic charge exist; what is the nature of dark matter; and, how did the big-bang develop. MoEDAL’s purpose is to meet such far-reaching challenges at the frontier of the field. The innovative MoEDAL detector employs unconventional methodologies tuned to the prospect of discovery physics. The largely passive MoEDAL detector, deployed at Point 8 on the LHC ring, has a dual nature. First, it acts like a giant camera, comprised of nuclear track detectors - analyzed offline by ultra fast scanning microscopes - sensitive only to new physics. Second, it is uniquely able to trap the particle messengers of physics beyond the Standard Model for further study. MoEDAL’s radiation environment is monitored by a state-of-the-art real-time TimePix pixel detector array. A new MoEDAL sub-detector to extend MoEDAL’s reach to millicharged, minimally ionizing, particles (MMIPs) is under study Finally we shall describe the next step for MoEDAL called Cosmic MoEDAL, where we define a very large high altitude array to take the search for highly ionizing avatars of new physics to higher masses that are available from the cosmos. -
EPS-HEP 2017 Report of Contributions
EPS-HEP 2017 Report of Contributions https://indico.cern.ch/e/epshep2017 EPS-HEP 2017 / Report of Contributions Theory overview on FCNC B-decays Contribution ID: 10 Type: Parallel Talk Theory overview on FCNC B-decays Thursday, 6 July 2017 09:00 (30 minutes) LHCb experiment at CERN has recently reported a set of measurements on lepton flavour univer- sality in b to s transitions showing a departure from the Standard Model predictions. I will review the main ideas recently put forward to make sense out of these intriguing hints. Focusing on the new physics explanation, I will discuss the correlated signals expected in other low- and high- energy observables, that could help clarify the mysterious signal. Experimental Collaboration Primary author: GRELJO, Admir (University of Zurich) Presenter: GRELJO, Admir (University of Zurich) Session Classification: Flavour and symmetries Track Classification: Flavour Physics and Fundamental Symmetries October 6, 2021 Page 1 EPS-HEP 2017 / Report of Contributions Charm Quark Mass with Calibrate … Contribution ID: 11 Type: Parallel Talk Charm Quark Mass with Calibrated Uncertainty Friday, 7 July 2017 12:35 (13 minutes) We determine the charm quark mass mc(mc) from QCD sum rules of moments of the vector cur- rent correlator calculated in perturbative QCD. Only experimental data for the charm resonances below the continuum threshold are needed in our approach, while the continuum contribution is determined by requiring self-consistency between various sum rules, including the one for the ze- roth moment. Existing data from the continuum region can then be used to bound the theoretical error. Our result is mc(mc) = 1272 ± 8 MeV for αs(MZ ) = 0:1182. -
Unification of Nature's Fundamental Forces
Unification of Nature’s Geoffrey B. West Fredrick M. Cooper Fundamental Forces Emil Mottola a continuing search Michael P. Mattis it was explicitly recognized at the time that basic research had an im- portant and seminal role to play even in the highly programmatic en- vironment of the Manhattan Project. Not surprisingly this mode of opera- tion evolved into the remarkable and unique admixture of pure, applied, programmatic, and technological re- search that is the hallmark of the present Laboratory structure. No- where in the world today can one find under one roof such diversity of talent dealing with such a broad range of scientific and technological challenges—from questions con- cerning the evolution of the universe and the nature of elementary parti- cles to the structure of new materi- als, the design and control of weapons, the mysteries of the gene, and the nature of AIDS! Many of the original scientists would have, in today’s parlance, identified themselves as nuclear or particle physicists. They explored the most basic laws of physics and continued the search for and under- standing of the “fundamental build- ing blocks of nature’’ and the princi- t is a well-known, and much- grappled with deep questions con- ples that govern their interactions. overworked, adage that the group cerning the consequences of quan- It is therefore fitting that this area of Iof scientists brought to Los tum mechanics, the structure of the science has remained a highly visi- Alamos to work on the Manhattan atom and its nucleus, and the devel- ble and active component of the Project constituted the greatest as- opment of quantum electrodynamics basic research activity at Los Alam- semblage of scientific talent ever (QED, the relativistic quantum field os. -
After Dinner Speech by Dr
1 After Dinner Speech by Dr. Josef Rembser CERN, Geneva 14 September 2009 Celebration in honour of Professor Herwig Schopper’s 85 th Birthday I. Dear Friends, honourable, dear Professor Schopper! On 28 February of this year, you celebrated your 85th Birthday. This evening we are looking back on this memorable date, wishing you many happy returns of the day. You have been blessed with a life full of harmony and accomplishments, always keeping young physically and intellectually. This is a special blessing granted to a person: Love and family, friendships and encounters, giving and receiving, working and achieving acknowledgements and honours in a fulfilling profession and in challenging missions. Tomorrow, a scientific Colloquium will honour you as researcher and scientific teacher . Today, on the eve of the colloquium, I would like to speak about Herwig Schopper as a research politician and a research manager . My personal remarks and remembrances will focus, dear Herwig Schopper, on the guiding contributions you made in shaping, promoting and advancing science and research and their relevant policies in Germany and in Europe. 2 Professor Heuer, I am grateful for your invitation. It is a pleasure for me to give today's After-Dinner speech in honour of our jubilee. For many years during my service in the German Ministry of Research and Technology (BMFT) in Bonn I had close personal and professional connections with you, dear Professor Schopper, regarding German science and research policy including CERN. II. In 1945, with the end of the 2 nd World War, Germany as guilty party and loser plunged the world and its own country into destruction and suffering, thus experiencing a historical catastrophe. -
PARTON and HADRON PRODUCTION in E+E- ANNIHILATION Stephen Wolfram California Institute of Technology, Pasadena, California 91125
549 * PARTON AND HADRON PRODUCTION IN e+e- ANNIHILATION Stephen Wolfram California Institute of Technology, Pasadena, California 91125 Ab stract: The production of showers of partons in e+e- annihilation final states is described according to QCD , and the formation of hadrons is dis cussed. Resume : On y decrit la production d'averses d� partons dans la theorie QCD qui forment l'etat final de !'annihilation e+ e , ainsi que leur transform ation en hadrons. *Work supported in part by the U.S. Department of Energy under contract no. DE-AC-03-79ER0068. SSt1 Introduction In these notes , I discuss some attemp ts e ri the cl!evellope1!1t of - to d s c be hadron final states in e e annihilation events ll>Sing. QCD. few featm11res A (barely visible at available+ energies} of this deve l"'P"1'ent amenab lle· are lt<J a precise and formal analysis in QCD by means of pe·rturbatirnc• the<J ry. lfor the mos t part, however, existing are quite inadle<!i""' lte! theoretical mett:l�ods one must therefore simply try to identify dl-iimam;t physical p.l:ten<0melilla tt:he to be expected from QCD, and make estll!att:es of dne:i.r effects , vi.th the hop·e that results so obtained will provide a good appro�::illliatimn to eventllLal'c ex act calculations . In so far as such estllma�es r necessa�y� pre�ise �r..uan- a e titative tests of QCD are precluded . On the ott:her handl , if QC!Ji is ass11l!med correct, then existing experimental data to inve•stigate its be may \JJ:SE•«f havior in regions not yet explored by theoreticalbe llJleaums . -
People and Things
People and things An irresistible photograph: at a StAC Christmas party. Laboratory Director Pief Panofsky was presented with a CERN T-shirt, which he promptly put on. With him in the picture are (left to right) Roger Gear hart playing a seasonal master of ceremonies role, J. J. Murray and Ed Seppi. On people Elected vice-president of the Amer ican Physical Society for this year is Robert E. Marshak of Virginia Polytechnic Institute and State Uni versity. He succeeds Maurice Goldhaberr who becomes president elect. The new APS president is Arthur Schawlow of Stanford. In the same elections, Columbia theorist Malvin Ruder man was elected to serve for four years as councillor-at-large. Gisbert zu Pulitz, Scientific Director of the Darmstadt Heavy Ion Linear Accelerator Laboratory and Profes sor of Physics at the University of Heidelberg, has been elected as the new Chairman of the Association of German Research Centres (Ar- beitsgemeinschaft der Grossfor- schungseinrichtungen in der Bun- desrepublik Deutschland), succeed ing Herwig Schopper. The Associa the American Association for the tion includes the Julich and Karls Advancement of Science. ruhe nuclear research centres, LEP optimization DESY, and the Max Planck Institute for Plasma Physics as well as other The detail of the LEP electron-posi centres in the technical and biome tron storage ring project continues dical fields. to be studied so as to optimize the Moves at Brookhaven machine parameters from the point of view of performance and of cost. Nick Samios, former chairman of This optimization stays within the Brookhaven's Physics Department, description of Phase I of LEP which becomes the Laboratory's Deputy was agreed by the Member States Director for High Energy and Nu at the CERN Council meeting in clear Physics. -
1 Introduction
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CERN Document Server 1 TWENTY FIVE YEARS OF ASYMPTOTIC FREEDOM David J. Gross Institute For Theoretical Physics, UCSB Santa Barbara, California, USA e-mail: [email protected] Abstract th On the o ccasion of the 25 anniversary of Asymptotic Freedom, celebrated at the QCD Euorconference 98 on Quantum Chro dynamics, Montp ellier, July 1998, I describ ed the discovery of Asymptotic Freedom and the emergence of QCD. 1 INTRODUCTION Science progresses in a much more muddled fashion than is often pictured in history b o oks. This is esp ecially true of theoretical physics, partly b ecause history is written by the victorious. Con- sequently, historians of science often ignore the many alternate paths that p eople wandered down, the many false clues they followed, the many misconceptions they had. These alternate p oints of view are less clearly develop ed than the nal theories, harder to understand and easier to forget, esp ecially as these are viewed years later, when it all really do es make sense. Thus reading history one rarely gets the feeling of the true nature of scienti c development, in which the element of farce is as great as the element of triumph. The emergence of QCD is a wonderful example of the evolution from farce to triumph. During a very short p erio d, a transition o ccurred from exp erimental discovery and theoretical confusion to theoretical triumph and exp erimental con rmation. In trying to relate this story, one must be wary of the danger of the p ersonal bias that o ccurs as one lo oks back in time. -
6.2 Transition Radiation
Contents I General introduction 9 1Preamble 11 2 Relevant publications 15 3 A first look at the formation length 21 4 Formation length 23 4.1Classicalformationlength..................... 24 4.1.1 A reduced wavelength distance from the electron to the photon ........................... 25 4.1.2 Ignorance of the exact location of emission . ....... 25 4.1.3 ‘Semi-bare’ electron . ................... 26 4.1.4 Field line picture of radiation . ............... 26 4.2Quantumformationlength..................... 28 II Interactions in amorphous targets 31 5 Bremsstrahlung 33 5.1Incoherentbremsstrahlung..................... 33 5.2Genericexperimentalsetup..................... 35 5.2.1 Detectors employed . ................... 35 5.3Expandedexperimentalsetup.................... 39 6 Landau-Pomeranchuk-Migdal (LPM) effect 47 6.1 Formation length and LPM effect.................. 48 6.2 Transition radiation . ....................... 52 6.3 Dielectric suppression - the Ter-Mikaelian effect.......... 54 6.4CERNLPMExperiment...................... 55 6.5Resultsanddiscussion....................... 55 3 4 CONTENTS 6.5.1 Determination of ELPM ................... 56 6.5.2 Suppression and possible compensation . ........ 59 7 Very thin targets 61 7.1Theory................................ 62 7.1.1 Multiple scattering dominated transition radiation . .... 62 7.2MSDTRExperiment........................ 63 7.3Results................................ 64 8 Ternovskii-Shul’ga-Fomin (TSF) effect 67 8.1Theory................................ 67 8.1.1 Logarithmic thickness dependence