DOCSLIB.ORG

Top Quark Physics in the Large Hadron Collider Era

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Top Quark Physics in the Large Hadron Collider Era Top Quark Physics in the Large Hadron Collider era Michael Russell Particle Physics Theory Group, School of Physics & Astronomy, University of Glasgow September 2017 arXiv:1709.10508v2 [hep-ph] 31 Jan 2018 A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy Abstract We explore various aspects of top quark phenomenology at the Large Hadron Collider and proposed future machines. After summarising the role of the top quark in the Standard Model (and some of its well-known extensions), we discuss the formulation of the Standard Model as a low energy effective theory. We isolate the sector of this effective theory that pertains to the top quark and that can be probed with top observables at hadron colliders, and present a global fit of this sector to currently available data from the LHC and Tevatron. Various directions for future improvement are sketched, including analysing the potential of boosted observables and future colliders, and we highlight the importance of using complementary information from different colliders. Interpretational issues related to the validity of the effective field theory formulation are elucidated throughout. Finally, we present an application of artificial neural network algorithms to identifying highly- boosted top quark events at the LHC, and comment on further refinements of our analysis that can be made. 2 Acknowledgements First and foremost I must thank my supervisors, Chris White and Christoph Englert, for their endless support, inspiration and encouragement throughout my PhD. They always gave me enough freedom to mature as a researcher, whilst providing the occasional neces- sary nudge to keep me on the right track. I also have to thank David Miller for his friendly advice and irreverent sense of humour, and for helping me settle into the group in Glasgow, and Christine Davies, for financial support for several research trips, and for creating a wonderful place to do physics. This thesis would not have been written without the foundations laid down by Liam Moore, so I have to thank him for the countless hours he has put into the project, and for being a mate. Of the other students in Glasgow, I also have to mention Karl Nordstr¨omfor many useful conversations, both about the work presented here and often tangential (but always illuminating) topics, and his occasional computational wizardry. In Heidelberg, special mention must go to Torben Schell, for his patience in showing me some of the many ropes of jet substructure, and to Tilman Plehn for stimulating collaboration, and for helping me start the next chapter in my life as a physicist. I thank the students and postdocs in both of these places for making such a friendly working environment. Throughout my PhD I have been fortunate to work with several excellent experimen- talists; James Ferrando and Andy Buckley in Glasgow, and Gregor Kasieczka in Z¨urich. I thank them for all they have taught me about collider physics (and especially Andy for coding assistance in the rocky early days of TopFitter), and I hope to collaborate with them again in the future. Though I never had the opportunity to work with Sarah Boutle or Chris Pollard directly, their unwavering fondness for a pint helped keep me sane after many a long day. Finally, I have to acknowledge the huge intellectual (and general) debt I owe to my parents. Though they do not share my passion for physics, they have always supported me along the way, and politely endured far too many wearisome physics rants to mention. This thesis is dedicated to them. Thanks also to Daniel and Lucy for trying to keep me in the real world. 3 Declaration I declare that this thesis is the result of my own original work and has not been previously presented for a degree. In cases where the work of others is presented, appropriate citations are used. Chapters 1 and 2 serve as an introduction to the research topics presented in the rest of the thesis. Chapters 3 to 5 are a result of my own original work, in collaboration with the authors listed below. Work appearing in this thesis was presented in the following publications [1{5]: A. Buckley, C. Englert, J. Ferrando, D. J. Miller, L. Moore, M. Russell, and C. D. • White, \Global fit of top quark effective theory to data," Phys. Rev. D92 no. 9, (2015) 091501, arXiv:1506.08845 [hep-ph]. A. Buckley, C. Englert, J. Ferrando, D. J. Miller, L. Moore, M. Russell, and C. D. • White, \Constraining top quark effective theory in the LHC Run II era," JHEP 04 (2016) 015, arXiv:1512.03360 [hep-ph]. C. Englert, L. Moore, K. Nordstr¨om, and M. Russell, \Giving top quark effective • operators a boost," Phys. Lett. B763 (2016) 9{15, arXiv:1607.04304 [hep-ph]. A. Buckley, C. Englert, J. Ferrando, D. J. Miller, L. Moore, K. Nordstr¨om,M. Russell, • and C. D. White, \Results from TopFitter," in 9th International Workshop on the CKM Unitarity Triangle (CKM 2016) Mumbai, India, November 28-December 3, 2016. 2016. arXiv:1612.02294 [hep-ph]. G. Kasieczka, T. Plehn, M. Russell, and T. Schell, \Deep-learning Top Taggers or • The End of QCD?," JHEP 05 (2017) 006, arXiv:1701.08784 [hep-ph]. C. Englert and M. Russell, \Top quark electroweak couplings at future lepton collid- • ers," Eur. Phys. J. C77 no. 8, (2017) 535, arXiv:1704.01782 [hep-ph]. My specific contributions to these chapters are as follows. In chapter 3, I set up the EFT fitting framework, and used the Mathematica model developed by Liam Moore to simulate events, construct theory observables and derive confidence limits on the operators considered. In chapter 4, I wrote the boosted analysis and derived the various projected limits on the operators considered. All numerical results in those chapters were derived by myself. In chapter 5, my contributions involved generating events, writing the analysis code to construct the fat jets and subsequent images used, formulating the boosted decision tree used as a comparison, and helping to design the neural network architecture used. All figures in this thesis were generated by the author, with the following exceptions: Fig. 3.2 (A. Buckley), Figs. 4.13-4.14 (C. Englert), Fig. 5.5 and Figs. 5.7-5.9 (T. Schell). 4 5 Contents A historical introduction 10 1 The top quark in the Standard Model 19 1.1 Introduction . 19 1.2 The Standard Model of Particle Physics . 19 1.2.1 Before electroweak symmetry breaking . 20 1.2.2 The Higgs mechanism . 25 1.2.3 The Higgs mechanism in the Standard Model . 28 1.2.4 The parameters of the Standard Model . 31 1.3 Hadron collider physics . 34 1.3.1 Scattering theory . 34 1.3.2 Scale uncertainties . 35 1.3.3 The parton densities . 37 1.3.4 Standard Model parameters . 37 1.4 Top quark physics at hadron colliders . 39 1.4.1 Top pair production . 40 1.4.2 Charge asymmetries . 43 1.4.3 Single top production . 45 1.4.4 Higher-order processes . 49 1.4.5 Top quark decay . 50 1.5 Summary . 51 2 The top quark beyond the Standard Model 52 2.1 Introduction . 52 2.2 Motivations for physics beyond the Standard Model . 52 2.2.1 The hierarchy problem . 52 2.2.2 Vacuum stability . 56 2.2.3 Gauge coupling unification . 59 2.2.4 Strong CP violation . 60 2.3 The role of the top quark in specific BSM scenarios . 61 2.3.1 Low energy supersymmetry . 61 2.3.2 Little Higgs . 63 2.3.3 Warped extra dimensions . 65 2.4 Principles of effective field theory . 67 6 2.4.1 The Euler-Heisenberg Lagrangian . 67 2.4.2 Fermi theory of weak decay . 69 2.4.3 Renormalisation group treatment . 70 2.5 The Standard Model effective field theory . 72 2.5.1 D =5 .................................. 73 2.5.2 D =6 .................................. 74 2.6 The top quark sector of the Standard Model effective theory . 77 2.6.1 Top pair production . 78 2.6.2 Single top production . 82 2.7 Summary . 82 3 A global fit of top quark effective theory to data 84 3.1 Introduction . 84 3.2 Higher-dimensional operators . 85 3.3 Methodology . 86 3.3.1 Experimental inputs . 86 3.3.2 Treatment of uncertainties . 87 3.3.3 Fitting procedure . 88 3.4 Results . 92 3.4.1 Top pair production . 93 3.4.2 Single top production . 96 3.4.3 Associated production . 99 3.4.4 Decay observables . 101 3.4.5 Charge asymmetries . 102 3.4.6 Contribution of individual datasets . 104 3.5 Validity of the EFT approach . 106 3.5.1 Impact of quadratic terms . 106 3.5.2 Overflow bins . 108 3.5.3 Constraining UV models . 110 3.6 Summary . 112 4 Future prospects for top quark EFT 116 4.1 Introduction . 116 4.2 Improving the fit with boosted reconstruction . 117 4.2.1 Analysis details . 119 7 4.2.2 Results . 122 4.2.3 Interpreting the results . 125 4.2.4 Discussion . 127 4.3 Associated Z production projections . 128 4.3.1 Top electroweak couplings . 128 4.3.2 Total rates . 130 4.3.3 Impact of differential distributions . 131 4.4 Future collider prospects . 132 4.4.1 The tt¯ total cross-section . 134 4.4.2 Polarised beams . 137 4.4.3 CLIC constraints . 138 + 4.5 Beyond e e− tt¯: Precision Observables . 140 ! 4.5.1 Oblique corrections . 140 4.5.2 Non-oblique corrections . 141 4.6 Summary . 142 5 Top tagging with Deep Neural Networks 144 5.1 Introduction .
Load more

Recommended publications
  • The Design and Performance of the ZEUS Micro Vertex Detector
    The design and performance of the ZEUS Micro Vertex Detector A. Polini University and INFN Bologna, Bologna, Italy1 I. Brock, S. Goers, A. Kappes, U. F. Katz, E. Hilger, J. Rautenberg, A. Weber Physikalisch.es Institut der Universitdt Bonn, Bonn, Germany2 2007 A. Mastroberardino, E. Tassi Caia&ria Dnireraitp, PApsica Department and DVPW, Coaenza, dtatp ^ Aug V. Adler, L. A. T. Bauerdick, L Bloch, T. Haas *, U. Klein, U. Koetz, G. Kramberger, 21 E. Lobodzinska, R. Mankel, J. Ng, D. Notz, M. C. Petrucci, B. Sarrow, G. Watt, C. Youngman, W. Zeuner Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany C. Coldewey, R. Heller Deutsches Elektronen-Synchrotron DESY, Zeuthen, Germany E. Gallo University and. INFN, Florence, Italy1 T. Carli, V. Chiochia, D. Dannheim, E. Fretwurst, A. Garfagnini, R. Klanner, B. Koppitz, J. Martens, M. Milite [physics.ins-det] Hamburg University, Institute of Exp. Physics, Hamburg, Germ.a.ny 3 Katsuo Tokushuku Institute of Particle and Nuclear Studies, KEK, Tsukuba, Japan.4 I. Redondo Dnireraidad Antonoma de Madrid, Madrid, .Spain ^ H. Boterenbrood, E. KofTeman, P. Kooijman, E. Maddox, H. Tiecke, M. Vazquez, J. Velthuis, L. Wiggers, NIKHEF and University of Amsterdam., Amsterdam, Netherlands 6 R.C.E. Devenish, M. Dawson, J. Ferrando, G. Grzelak, K. Korcsak-Gorzo, T. Matsushita, K. Oliver, P. Shield, R. Walczak arXiv:0708.3011vl Department o/ f Apaics, Dnireraitp o/ Oa^ord, Oa^ord, United kingdom ' DESYOT-131 A. Bertolin, E. Borsato, R. Carlin, F. Dal Corso, A. Longhin, M. Turcato Dipartimento di Fisica dell' University and INFN, Padova, Italy*1 T. Fusayasu, R. Hori, T. Kohno, S. Shimizu Department of Physics, University of Tokyo, Tokyo, Japan 4 H.
    [Show full text]
  • The Large Hadron Collider Lyndon Evans CERN – European Organization for Nuclear Research, Geneva, Switzerland
    34th SLAC Summer Institute On Particle Physics (SSI 2006), July 17-28, 2006 The Large Hadron Collider Lyndon Evans CERN – European Organization for Nuclear Research, Geneva, Switzerland 1. INTRODUCTION The Large Hadron Collider (LHC) at CERN is now in its final installation and commissioning phase. It is a two-ring superconducting proton-proton collider housed in the 27 km tunnel previously constructed for the Large Electron Positron collider (LEP). It is designed to provide proton-proton collisions with unprecedented luminosity (1034cm-2.s-1) and a centre-of-mass energy of 14 TeV for the study of rare events such as the production of the Higgs particle if it exists. In order to reach the required energy in the existing tunnel, the dipoles must operate at 1.9 K in superfluid helium. In addition to p-p operation, the LHC will be able to collide heavy nuclei (Pb-Pb) with a centre-of-mass energy of 1150 TeV (2.76 TeV/u and 7 TeV per charge). By modifying the existing obsolete antiproton ring (LEAR) into an ion accumulator (LEIR) in which electron cooling is applied, the luminosity can reach 1027cm-2.s-1. The LHC presents many innovative features and a number of challenges which push the art of safely manipulating intense proton beams to extreme limits. The beams are injected into the LHC from the existing Super Proton Synchrotron (SPS) at an energy of 450 GeV. After the two rings are filled, the machine is ramped to its nominal energy of 7 TeV over about 28 minutes. In order to reach this energy, the dipole field must reach the unprecedented level for accelerator magnets of 8.3 T.
    [Show full text]
  • Collider Physics at HERA
    ANL-HEP-PR-08-23 Collider Physics at HERA M. Klein1, R. Yoshida2 1University of Liverpool, Physics Department, L69 7ZE, Liverpool, United Kingdom 2Argonne National Laboratory, HEP Division, 9700 South Cass Avenue, Argonne, Illinois, 60439, USA May 21, 2008 Abstract From 1992 to 2007, HERA, the first electron-proton collider, operated at cms energies of about 320 GeV and allowed the investigation of deep-inelastic and photoproduction processes at the highest energy scales accessed thus far. This review is an introduction to, and a summary of, the main results obtained at HERA during its operation. To be published in Progress in Particle and Nuclear Physics arXiv:0805.3334v1 [hep-ex] 21 May 2008 1 Contents 1 Introduction 4 2 Accelerator and Detectors 5 2.1 Introduction.................................... ...... 5 2.2 Accelerator ..................................... ..... 6 2.3 Deep Inelastic Scattering Kinematics . ............. 9 2.4 Detectors ....................................... .... 12 3 Proton Structure Functions 15 3.1 Introduction.................................... ...... 15 3.2 Structure Functions and Parton Distributions . ............... 16 3.3 Measurement Techniques . ........ 18 3.4 Low Q2 and x Results .................................... 19 2 3.4.1 The Discovery of the Rise of F2(x, Q )....................... 19 3.4.2 Remarks on Low x Physics.............................. 20 3.4.3 The Longitudinal Structure Function . .......... 22 3.5 High Q2 Results ....................................... 23 4 QCD Fits 25 4.1 Introduction.................................... ...... 25 4.2 Determinations ofParton Distributions . .............. 26 4.2.1 TheZEUSApproach ............................... .. 27 4.2.2 TheH1Approach................................. .. 28 4.3 Measurements of αs inInclusiveDIS ............................ 29 5 Jet Measurements 32 5.1 TheoreticalConsiderations . ........... 32 5.2 Jet Cross-Section Measurements . ........... 34 5.3 Tests of pQCD and Determination of αs .........................
    [Show full text]
  • Neutral Strangeness Production with the ZEUS Detector at HERA
    Neutral Strangeness Production with the ZEUS Detector at HERA Chuanlei Liu Department of Physics McGill University, Montreal, QC Canada January 2007 A thesis submitted to McGill University in partial fulfillment of the requirements of the degree of Doctor of Philosophy Chuanlei Liu, 2007 Abstract ¯ 0 The inclusive production of the neutral strange particles, Λ, Λ and KS, has been studied with the ZEUS detector at HERA. The measurement provides a way to understand the fragmentation process in ep collisions and to check the universality of this process. The strangeness cross sections have been measured and compared with Monte Carlo (MC) predictions. Over the kinematic regions of interest, no Λ ¯ 0 to Λ asymmetry was observed. The relative yield of Λ and KS was determined and the result was compared with MC calculations and results from other experiments. A good agreement was found except for the enhancement in the photoproduction process. Clear rapidity correlation was observed for particle pairs where either quark 0 0 flavor or baryon number compensation occurs. The KSKS Bose-Einstein correlation measurement gives a result consistent with those from LEP measurements. The Λ polarizations were measured to be consistent with zero for HERA I data. i ii Abstract Abstract in French ¯ 0 La mesure de production inclusive des particules ´etranges neutres Λ, Λ et KS avec le d´etecteur ZEUS a` HERA permet de comprendre le processus de fragmentation dans les collisions ep et de v´erifier son universalit´e. Les sections efficaces de produc- tion d'´etranget´e ont ´et´e mesur´ees et compar´ees avec les pr´edictions de simulations Monte-Carlo (MC).
    [Show full text]
  • Experience of EW and BSM Physics at HERA and Lessons for EIC
    Experience of EW and BSM physics at HERA and lessons for EIC Elisabetta Gallo (DESY and UHH) (A personal recollection and selection of topics) Electroweak and BSM physics at the EIC, 6/5/2020 Elisabetta Gallo (DESY) 1 HERA (1992-2007) First F2 presented by H1 at Diffractive events Durham 1993 discovered by ZEUS, DESY seminar 1993 • HERA experiments were built for high Q2 physics, F from H1 but adapted very well to lower Q2 low x L • With HERA II a stronger electroweak program coulD be starteD anD searches boosteD • At the enD of HERA II we went back to low-x physics with FL Elisabetta Gallo (DESY) 2 Increasing the luminosity (i.e. HERA II) • Access to higher Q2 • Access to valence quark distribution at higher x in NC, xF3 • Electron vs positron running (endless discussions) • More precise measurements of charged current • Polarized beams • Combination H1-ZEUS data (it started for xF3) • LHC was getting closer -> PDFs for LHC, more exchange, HERAPDFs • More exotic searches • Isolated leptons plus missing energy and large hadronic p Triggered by observation in T H1, no specific- related search • Multilepton events • Leptoquarks • FCNC • Contact interactions Elisabetta Gallo (DESY) 3 NC/CC at high Q2 Elisabetta Gallo (DESY) 4 Few words about ZEUS and H1 combinations • Unless specified the plots I am going to show are based on the latest combined data • And compared to HERAPDF2.0: based on data taken 1994-2007, 2927 points combined to 1307, 21 HERA I data samples, 20 HERA II data samples NC+CC EPJ C75 (2015) 580 • xFitter, open-source tool originally started • NC: 0.045< Q2< 50000 to fit PDFs at HERA GeV2 -7 ZEUS and H1 combination • Now used also for LHC 6 X 10 < x < 0.65 • CC: 200< Q2< 50000 is the main dataset for experiments (EIC?) PDFs fitters GeV2 1.3 X 10-2 < x < 0.40 Elisabetta Gallo (DESY) 5 Polarization at HERA II • EleCtrons/positrons get naturally transverse polarized (Solokov-Ternov effeCt) • Spin rotators to Change in long.
    [Show full text]
  • MIT at the Large Hadron Collider—Illuminating the High-Energy Frontier
    Mit at the large hadron collider—Illuminating the high-energy frontier 40 ) roland | klute mit physics annual 2010 gunther roland and Markus Klute ver the last few decades, teams of physicists and engineers O all over the globe have worked on the components for one of the most complex machines ever built: the Large Hadron Collider (LHC) at the CERN laboratory in Geneva, Switzerland. Collaborations of thousands of scientists have assembled the giant particle detectors used to examine collisions of protons and nuclei at energies never before achieved in a labo- ratory. After initial tests proved successful in late 2009, the LHC physics program was launched in March 2010. Now the race is on to fulfill the LHC’s paradoxical mission: to complete the Stan- dard Model of particle physics by detecting its last missing piece, the Higgs boson, and to discover the building blocks of a more complete theory of nature to finally replace the Standard Model. The MIT team working on the Compact Muon Solenoid (CMS) experiment at the LHC stands at the forefront of this new era of particle and nuclear physics. The High Energy Frontier Our current understanding of the fundamental interactions of nature is encap- sulated in the Standard Model of particle physics. In this theory, the multitude of subatomic particles is explained in terms of just two kinds of basic building blocks: quarks, which form protons and neutrons, and leptons, including the electron and its heavier cousins. From the three basic interactions described by the Standard Model—the strong, electroweak and gravitational forces—arise much of our understanding of the world around us, from the formation of matter in the early universe, to the energy production in the Sun, and the stability of atoms and mit physics annual 2010 roland | klute ( 41 figure 1 A photograph of the interior, central molecules.
    [Show full text]
  • Three-Jet Production in Neutral Current Deep Inelastic Scattering with ZEUS Detector at HERA
    Three-jet Production in Neutral Current Deep Inelastic Scattering with ZEUS Detector at HERA Preliminary Examination Liang Li University of Wisconsin Nov 27,2001 HERA • 820/920 GeV proton • 27.5 GeV electrons or positrons • 300/318 GeV center of mass energy • 220 bunches 96 ns crossing time • Instantaneous luminosity 1.8 x 1031 cm-2s-1 • Currents: ~90mA protons ~40mA positrons HERA Luminosity . 820 GeV protons through 1997 920 GeV since 1998 . ZEUS integrated luminosity since 1992: ~185 pb-1 . Expect 1fb-1 by end of 2005 HERA Kinematic Range Extended kinematic region not accessible by fixed target experiments, with some overlap. H1 and ZEUS: DESY e-p HERMES: DESY e-A E665: Fermilab µ-A BCDMS: CERN µ-A CCFR: Fermilab ν-A SLAC: many experiments e-A NMC: CERN µ-A Deep Inelastic Scattering W2 = (p+q)2 W=invariant mass of the final hadronic system e+pDIS Event at HERA DIS Cross Section 2 F2 (x,Q ): Interaction between transversely polarized photons & spin 1/2 partons ; Charge weighted sum of the quark distributions 2 FL (x,Q ): Interaction between longitudinally polarized photons & the partons with transverse momentum. 2 0 F3 (x,Q ): Parity-violating structure function from Z exchange. Naïve Quark Parton Model · Partons are point-like objects · No interaction between the partons · Structure function independent of Q2 Bjorken Scaling (x) dependence: − F (x,Q2) =∑ e 2(Q2) ·(xq(x,Q2) +xq(x,Q2)) 2 quarks q 2 → F2(x,Q ) F2(x), FL= 0 QCD Physics picture: presence of gluons Parton Parton interactions, mediated by gluons Generate parton transverse momentum Non zero FL The structure functions gain a Q2 dependence Scaling Violation Scaling Violation Parton Distribution Functions Derived from the experiment DGLAP Evolution Dokshitzer-Gribov-Lipatov-Altarelli-Parisi equations describe evolution of parton densities to higher Q2 — QCD prediction α s is the strong coupling constant.
    [Show full text]
  • ZEUS EXPERIMENT at HERA ' ZEUS Collaboration 2 Group from the Institute of Nuclear Physics Includes: P
    PL9700208 28 Section V ,.,.-; ZEUS EXPERIMENT AT HERA ' ZEUS Collaboration 2 Group from the Institute of Nuclear Physics includes: P. Borzeniski, J. Chwastowski, A. Eskreys, K. Piotrzkowski, M. Przybycieri, M. Zachara, L. Zawiejski (physicists) and J. Andruszkow, B. Dajarowski, W. Daniluk, P. Jurkiewicz, A. Kotarba, K. Oliwa. W. Wierba (engineers and technicians) Third year of HERA operation was a very successful one for the HERA crew. Experiments (ZEUS and HI) collected more than 3pb~1 of the integrated luminosity compared to ()00nb~^ in the previous year. Higher luminosity means also higher rates and higher background. That created new problems for our experiment at the beginning of the running period. The common effort of all groups taking care of the different detector components resulted in a smooth and successful running of the ZEUS experiment. The main responsibility of the Cracow group is the reliable performance of the Luminosity Monitor, which has been designed and built by our group. That means the maintenance of the detector, continuous development of the online and offline software tools and the luminosity measurement itself. A very detailed offline analysis of the 1993 luminosity data was done in 1994. This resulted in much better understanding of the systematic effects influencing the luminosity measurement. The systematic error in the determination of the integrated luminosity is now below 2.5%. Modification of the hardware setup, especially replacement of the photomultipliers in the calorimeters, made during the 1993/1994 winter shutdown, allowed for more stable opera- tion in the 1994 running period. Much improvement has also been achieved in both offline and online software.
    [Show full text]
  • The Transformative Energy of Children's Literature
    Notes 1 Breaking Bounds: The Transformative Energy of Children’s Literature 1. I do not recognise Karin Lesnik-Oberstein’s insistence that the majority of academics who write about children’s literature are primarily concerned with finding the right book for the right child (Children’s Literature: New Approaches, 2004: 1–24). 2. Although publishing for children includes many innovative and important non- fictional works, my concern is specifically with narrative fictions for children. 3. See Rumer Godden’s entertaining ‘An Imaginary Correspondence’ featuring invented letters between Mr V. Andal, an American publisher working for the De Base Publishing Company, and Beatrix Potter for an entertaining insight into this process. The piece appeared in Horn Book Magazine 38 (August 1963), 197–206. 4. Peter Hunt raises questions about the regard accorded to Hughes’s writing for children suggesting that it derives more from the insecurity of children’s literature critics than the quality of the work: ‘It is almost as if, with no faith in their own judgements, such critics are glad to accept the acceptance of an accepted poet’ (2001: 79–81). 5. See Reynolds and Tucker, 1998; Trites, 2000 and Lunden, 2004. 6. Although writing in advance of Higonnet, Rose would have been familiar with many of the examples on which Pictures of Innocence is based. 7. By the time she reaches her conclusion, Rose has modified her position to empha- sise that ‘children’s literature is just one of the areas in which this fantasy is played out’ (138), undermining her claims that the child-audience is key to the work of children’s literature in culture.
    [Show full text]
  • The Birth and Development of the First Hadron Collider the Cern Intersecting Storage Rings (Isr)
    Subnuclear Physics: Past, Present and Future Pontifical Academy of Sciences, Scripta Varia 119, Vatican City 2014 www.pas.va/content/dam/accademia/pdf/sv119/sv119-hubner.pdf The BirtTh a nd D eve lopment o f the Fir st Had ron C ollider The CERN Intersecting Storage Rings (ISR) K. H ÜBNER , T.M. T AYLOR CERN, 1211 Geneva 23, Switzerland Abstract The CERN Intersecting Storage Rings (ISR) was the first facility providing colliding hadron beams. It operated mainly with protons with a beam energy of 15 to 31 GeV. The ISR were approved in 1965 and were commissioned in 1971. This paper summarizes the context in which the ISR emerged, the design and approval phase, the construction and the commissioning. Key parameters of its performance and examples of how the ISR advanced accelerator technology and physics are given. 1. Design and approval The concept of colliding beams was first published in a German patent by Rolf Widerøe in 1952, but had already been registered in 1943 (Widerøe, 1943). Since beam accumulation had not yet been invented, the collision rate was too low to be useful. This changed only in 1956 when radio-frequency (rf) stacking was proposed (Symon and Sessler, 1956) which allowed accumulation of high-intensity beams. Concurrently, two realistic designs were suggested, one based on two 10 GeV Fixed-Field Alternating Gradient Accelerators (FFAG) (Kerst, 1956) and one suggesting two 3 GeV storage rings with synchrotron type magnet structure (O’Neill, 1956); in both cases the beams collided in one common straight section. The idea of intersecting storage rings to increase the number of interaction points appeared later (O’Neill, 1959).
    [Show full text]
  • Physicists Raid Tevatron for Parts Fermilab Icon Plundered Amid Tight Budgets and Shifting Scientific Aims
    IN FOCUS NEWS HIGH-ENERGY PHYSICS Physicists raid Tevatron for parts Fermilab icon plundered amid tight budgets and shifting scientific aims. BY EUGENIE SAMUEL REICH CANNIBALIZING THE TEVATRON Parts at the Tevatron and its two main experiments, the CDF and D0, are being t is a 4,000-tonne edifice that stands three considered for recycling in the wake of the collider’s closure in September 2011. stories high, chock full of particle detectors, Antiproton power supplies, electronics and photo­ source Imultiplier tubes, all layered like a giant onion Possibly open around a cylindrical magnet. During 26 years Booster of operation at the Fermi National Accelerator to visitors Laboratory in Batavia, Illinois, this behemoth, Main injector the Collider Detector at Fermilab (CDF), and recycler helped to find the top quark and chased the • Photomultiplier tubes for Higgs boson. But since the lab’s flagship parti- nuclear-structure experiment CDF cle collider, the Tevatron, was switched off in • Electronics for the Large September 2011, the detector has been surplus Hadron Collider in Europe • Central magnet for a stock — and it is now slowly being cannibal- possible particle-decay ized for parts. Beams repurposed experiment When the Tevatron closed, Fermilab for neutrino and • Possible educational display announced that the CDF would become an other experiments educational display. Along with its companion experiment, D0, the detector was supposed to form the centre­piece of a tour through simu- Tevatron lated control rooms and decommissioned Possible educational display accelerator tunnels. But tight budgets for experimental particle physicists — combined 500 m with their tendency to tinker and recycle — are pushing the outcome in a different direction, D0 at least for the CDF.
    [Show full text]
  • James Joyce (Irish)
    ANALYSIS “Clay” (1914) James Joyce (Irish) (1882-1941) “Clay” from Dubliners is typical of Joyce the Modernist, whose perspective in the story is suggested by the physiognomy of that elusive corkscrew. Everything depends upon the reader being more perceptive than Joe Donnelly, for almost every detail of the story implies opposites or contradictions, the essence of irony. Reading on all levels simultaneously is somewhat like playing three-dimensional chess. Maria the central figure is a soul of clay, one of many old maids in Dubliners, isolated between the Flynn sisters and the Morkan sisters. Her spinsterhood invokes the most obvious and for her the most painful ironies: “Lizzie Fleming said Maria was sure to get the ring.” Maria pretends “she didn’t want any ring or any man either,” and laughs with “disappointed shyness.” The stylish bakery clerk “asked her was it a wedding cake she wanted to buy,” and Maria pretends amusement, blushing. In the saucer game Joyce emphasizes symbolic appropriateness rather than irony by having Maria miss the ring and get the clay (death). But her response is the most crucial irony in the story, at least as far as she personally is concerned: “Maria understood that it was wrong that time.” All present are relieved to see her get the prayer-book the next time; for them the appropriate choice is the abhorrent choice. “Soon they were all quite merry again and Mrs. Donnelly said Maria would enter a convent before the year was out because she had got the prayer-book.” Joe asks the old lady to sing “some little song before she went.” In her embarrassment Maria seems to sense some of the irony of her romantic song from The Bohemian Girl and it may be this partial consciousness which causes her to omit a stanza about a lover.
    [Show full text]