The Higgs Boson in the Periodic System of Elementary Particles
Total Page：16
File Type：pdf, Size：1020Kb
Load more
Recommended publications
-
Search for Exotics with Top at ATLAS
Search for exotics with top at ATLAS Diedi Hu Columbia University On behalf of the ATLAS collaboration EPSHEP2013, Stockholm July 18, 2013 Motivation Motivation Due to its large mass, top quark offers a unique window to search for new physics: mt ∼ ΛEWSB (246GeV): top may play a special role in the EWSB Many extensions of the SM explain the large top mass by allowing the top to participate in new dynamics. Approaches of new physics search Measure top quark properties: check with SM prediction. Directly search for new particles coupling to top tt resonances searches Search for anomalous single top production Vector-like quarks searches (Covered in another talk "Searches for fourth generation vector-like quarks with the ATLAS detector") Search for exotics with tt and single top D.Hu, Columbia Univ. 2 / 16 tt resonance search with 14.3 fb−1 @ 8TeV tt resonance: benchmark models 2 specific models used as examples of sensitivity Leptophobic topcolor Z 0 [2] Explains the top quark mass and EWSB through top quark condensate Z 0 couples strongly only to the first and third generation of quarks Narrow resonance: Γ=m 1:2% ∼ Kaluza-Klein gluons [3] Predicted by the Bulk Randall-Sundrum models with warped extra dimension Strongly coupled to the top quark Broad resonance: Γ=m 15% ∼ Search for exotics with tt and single top D.Hu, Columbia Univ. 3 / 16 tt resonance search with 14.3 fb−1 @ 8TeV tt resonance: lepton+jets(I) [4] Backgrounds SM tt, Z+jets, single top, diboson and W+jets shape: directly from MC W+jets normalization, multijet: estimated from data Event selection One top decays hadronically and The boosted selection the other semileptonically. -
Higgs Bosons Strongly Coupled to the Top Quark
CERN-TH/97-331 SLAC-PUB-7703 hep-ph/9711410 November 1997 Higgs Bosons Strongly Coupled to the Top Quark Michael Spiraa and James D. Wellsb aCERN, Theory Division, CH-1211 Geneva, Switzerland bStanford Linear Accelerator Center Stanford University, Stanford, CA 94309† Abstract Several extensions of the Standard Model require the burden of electroweak sym- metry breaking to be shared by multiple states or sectors. This leads to the possibility of the top quark interacting with a scalar more strongly than it does with the Stan- dard Model Higgs boson. In top-quark condensation this possibility is natural. We also discuss how this might be realized in supersymmetric theories. The properties of a strongly coupled Higgs boson in top-quark condensation and supersymmetry are described. We comment on the difficulties of seeing such a state at the Tevatron and LEPII, and study the dramatic signatures it could produce at the LHC. The four top quark signature is especially useful in the search for a strongly coupled Higgs boson. We also calculate the rates of the more conventional Higgs boson signatures at the LHC, including the two photon and four lepton signals, and compare them to expectations in the Standard Model. CERN-TH/97-331 SLAC-PUB-7703 hep-ph/9711410 November 1997 †Work supported by the Department of Energy under contract DE-AC03-76SF00515. 1 Introduction Electroweak symmetry breaking and fermion mass generation are both not understood. The Standard Model (SM) with one Higgs scalar doublet is the simplest mechanism one can envision. The strongest arguments in support of the Standard Model Higgs mechanism is that no experiment presently refutes it, and that it allows both fermion masses and electroweak symmetry breaking. -
Introduction to Elementary Particle Physics
Introduction to Elementary Particle Physics Joachim Meyer DESY Lectures DESY Summer Student Program 2009 Preface ● This lecture is not a powerpoint show ● This lecture does not substitute an university course ● I know that your knowledge about the topic varies a lot ● So we have to make compromises in simplicity and depth ● Still I hope that all of you may profit somehow ● The viewgraphs shown are only for illustrations ● We will develop things together in discussion and at blackboard ● I hope there are lots of questions. I shall ask you a lot 2 Structures at different sizes Elementary Particle Physics 3 3 Fermion Generations Interactions through Gauge Boson Exchange This lecture is going to tell you something about HOW we arrived at this picture 4 Content of this lectures . Its only a sketch : Depending on your preknowledge we will go more or less in detail in the different subjects 5 6 WHY High Energies ? 7 The very basic minimum you have to know about Relativistic Kinematics 8 Which CM-energy do we reach at HERA ? 9 HEP 100 Years ago : Radioactive Decay Energy region : MeV =He−nucleus....=electron...= photon 10 Today : Some more particles : 11 The Particle Zoo I can't spare you this chapter. Quarks are nice to EXPLAIN observed phenomena. But, what we OBSERVE are particles like protons, muons, pions,.......... 12 'Artificial' Production of New Particles (Resonances): − p scattering 13 Particle classification Hadrons : strongly interacting Leptons : not Strongly interacting 14 All these particles are listed in the Particle Data Booklet -
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. -
Elementary Particle Physics from Theory to Experiment
Elementary Particle Physics From Theory to Experiment Carlos Wagner Physics Department, EFI and KICP, Univ. of Chicago HEP Division, Argonne National Laboratory Society of Physics Students, Univ. of Chicago, Nov. 10, 2014 Particle Physics studies the smallest pieces of matter, 1 1/10.000 1/100.000 1/100.000.000 and their interactions. Friday, November 2, 2012 Forces and Particles in Nature Gravitational Force Electromagnetic Force Attractive force between 2 massive objects: Attracts particles of opposite charge k e e F = 1 2 d2 1 G = 2 MPl Forces within atoms and between atoms Proportional to product of masses + and - charges bind together Strong Force and screen each other Assumes interaction over a distance d ==> comes from properties of spaceAtoms and timeare made fromElectrons protons, interact with protons via quantum neutrons and electrons. Strong nuclear forceof binds e.m. energy together : the photons protons and neutrons to form atoms nuclei Strong nuclear force binds! togethers! =1 m! = 0 protons and neutrons to form nuclei protonD. I. S. of uuelectronsd formedwith Modeled protons by threeor by neutrons a theoryquarks, based bound on together Is very weak unless one ofneutron theat masses high energies is huge,udd shows by thatthe U(1)gluons gauge of thesymmetry strong interactions like the earth protons and neutrons SU (3) c are not fundamental Friday,p November! u u d 2, 2012 formed by three quarks, bound together by n ! u d d the gluons of the strong interactions Modeled by a theory based on SU ( 3 ) C gauge symmetry we see no free quarks Very strong at large distances confinement " in nature ! Weak Force Force Mediating particle transformations Observation of Beta decay demands a novel interaction Weak Force Short range forces exist only inside the protons 2 and neutrons, with massive force carriers: gauge bosons ! W and Z " MW d FW ! e / d Similar transformations explain the non-observation of heavier elementary particles in our everyday experience. -
New Elementary Particle Evidence Found, 'Sterile Neutrino' Long
New elementary particle evidence found, ‘sterile neutrino’ long suspected June 6, 2018 Los Alamos experiment at Fermilab explores potential ‘dark matter’ link, confirms earlier experiment LOS ALAMOS, N.M., June 6, 2018—New research results have potentially identified a fourth type of neutrino, a “sterile neutrino” particle. This particle provides challenges for the Standard Model of particle physics, if found to be a valid result in future experiments. The work, conducted by a multi-institutional team at Fermi National Accelerator Laboratory (Fermilab) near Chicago, confirms results found in the 1990s in the Los Alamos Liquid Scintillator Neutrino Detector (LSND). “This is a fascinating step forward for particle physics,” said Los Alamos National Laboratory Director Terry Wallace. “Of course, this needs to be tempered by #the fact that future observations are required to really clinch this beyond any shadow of doubt. Modifications to the Standard Model, including dark matter, new particles and other interpretations of this result are still speculative. What stands with high confidence is that two experiments with completely different approaches observe the same effect.” 1:22 The Sterile Neutrino Discovery Neutrinos, traditionally understood to come in three “flavors,” electron, muon and tau, have been measured by the Mini Booster Neutrino Experiment (MiniBooNE) for some 15 years. The key to the current result is the existence of more electron-flavored neutrinos than expected. Neutrinos normally oscillate between the three types, but the overpopulation of the electron-flavored ones leads to a theory that some of the muon neutrinos became sterile neutrinos for a time during the regular oscillations. The sterile neutrinos could reasonably be assumed to have transitioned into electron neutrinos in their next oscillation phase, thus explaining the higher electron numbers. -
Supersymmetry: What? Why? When?
Contemporary Physics, 2000, volume41, number6, pages359± 367 Supersymmetry:what? why? when? GORDON L. KANE This article is acolloquium-level review of the idea of supersymmetry and why so many physicists expect it to soon be amajor discovery in particle physics. Supersymmetry is the hypothesis, for which there is indirect evidence, that the underlying laws of nature are symmetric between matter particles (fermions) such as electrons and quarks, and force particles (bosons) such as photons and gluons. 1. Introduction (B) In addition, there are anumber of questions we The Standard Model of particle physics [1] is aremarkably hope will be answered: successful description of the basic constituents of matter (i) Can the forces of nature be uni® ed and (quarks and leptons), and of the interactions (weak, simpli® ed so wedo not have four indepen- electromagnetic, and strong) that lead to the structure dent ones? and complexity of our world (when combined with gravity). (ii) Why is the symmetry group of the Standard It is afull relativistic quantum ®eld theory. It is now very Model SU(3) ´SU(2) ´U(1)? well tested and established. Many experiments con® rmits (iii) Why are there three families of quarks and predictions and none disagree with them. leptons? Nevertheless, weexpect the Standard Model to be (iv) Why do the quarks and leptons have the extendedÐ not wrong, but extended, much as Maxwell’s masses they do? equation are extended to be apart of the Standard Model. (v) Can wehave aquantum theory of gravity? There are two sorts of reasons why weexpect the Standard (vi) Why is the cosmological constant much Model to be extended. -
NEW ENTITIES, OLD PARADIGMS: ELEMENTARY PARTICLES in the 1930S1
LUE,, vol. 27,2004,435-464 NEW ENTITIES, OLD PARADIGMS: ELEMENTARY PARTICLES IN THE 1930s1 JAUME NAVARRO Cambridge University RESUMEN Al3STRACT En este artículo pretendo analizar los The aim of this paper is to analyse the procesos por los cuales se descubrieron y processes by which a number of new ele- aceptaron nuevas partículas elementales mentary particles were discovered and en los años anteriores a la segunda guerra accepted by the scientific community in the mundiaL Muchos libros de divulgación de years before World War 11. Many popular física de partículas elementales suelen accounts of particle physics depict a linear narrar una historia lineal sobre la bŭsque- history of the search for the ultimate con- da de las ŭltimas partículas constitutivas stituents of matter, which would start in de la materia. Ésta empezaría en 1897, 1897, with the discovery of the electron, con el descubrimiento del electrón, y and move on to an increasing number of avanzaría linealmente añadiendo nuevas new particles: photon, proton, neutron, partículas: fotones, protones, neutrones, positron, neutrino... Nevertheless, the positrones, neutrinos, etc. Sin embargo, el question about the building-blocks of the problema de los elementos constitutivos material world seems to have been a sec- de la materia no era un tema central de la ondary concern for physidsts who were fisica en la década de 1930. En sentido involved in the discovery of the new ele- estricto, se puede asegurar que antes de la mentary particles in the 1930s. In the segunda guerra mundial no existz'a una strong sense, one can argue that there was nueva disciplina de partículas elementales no such thing as a new discipline of particle en física. -
Anatomy of Top-Mode Extended Technicolor Model
December 9, 2018 Anatomy of Top-Mode Extended Technicolor Model ∗ Hidenori Fukano† and Koichi Yamawaki‡ Department of Physics, Nagoya University Nagoya 464-8602, Japan Abstract We analyze two versions of the extended technicolor (ETC) incorporating the top quark condensate via the flavor-universal coloron type topcolor SU(3) 1 × SU(3)2: A straightforward top-mode ETC having quarks and techniquarks as- signed to a single (strong) SU(3)1, and a “twisted model” with techniquarks carrying the weak SU(3)2 while quarks the strong SU(3)1. The straightforward model has the same ETC structure as that of Appelquist et al. without top- color which we first analyze to find that it yields only too small ETC-induced mass for the third generation. In contrast, our model having topcolor takes the form of a version of the topcolor-assisted technicolor (TC2) after ETC breakings, which triggers the top quark condensate giving rise to a realistic top mass. How- ever, techniquarks have the strong topcolor SU(3)1 in addition to the already strong walking/conformal technicolor, which triggers the techniquark condensate arXiv:0801.3716v2 [hep-ph] 19 Feb 2008 at scale much higher than the weak scale, a disaster. We then consider a “twisted model” of TC2, though not an explicit ETC. We find a new feature that “ETC”- induced quark mass is enhanced to the realistic value by the large anomalous dimension γ 2 of Nambu-Jona-Lasinio-type topcolor interactions. The result m ≃ roughly reproduces the realistic quark masses. We further find a novel effect of the above large anomalous dimension γ 2: The top-pion mass has a universal m ≃ upper bound, mπt < 70 GeV, in the generic TC2 model. -
B Meson Decays Marina Artuso1, Elisabetta Barberio2 and Sheldon Stone*1
Review Open Access B meson decays Marina Artuso1, Elisabetta Barberio2 and Sheldon Stone*1 Address: 1Department of Physics, Syracuse University, Syracuse, NY 13244, USA and 2School of Physics, University of Melbourne, Victoria 3010, Australia Email: Marina Artuso - [email protected]; Elisabetta Barberio - [email protected]; Sheldon Stone* - [email protected] * Corresponding author Published: 20 February 2009 Received: 20 February 2009 Accepted: 20 February 2009 PMC Physics A 2009, 3:3 doi:10.1186/1754-0410-3-3 This article is available from: http://www.physmathcentral.com/1754-0410/3/3 © 2009 Stone et al This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/ licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract We discuss the most important Physics thus far extracted from studies of B meson decays. Measurements of the four CP violating angles accessible in B decay are reviewed as well as direct CP violation. A detailed discussion of the measurements of the CKM elements Vcb and Vub from semileptonic decays is given, and the differences between resulting values using inclusive decays versus exclusive decays is discussed. Measurements of "rare" decays are also reviewed. We point out where CP violating and rare decays could lead to observations of physics beyond that of the Standard Model in future experiments. If such physics is found by directly observation of new particles, e.g. in LHC experiments, B decays can play a decisive role in interpreting the nature of these particles. -
Supersymmetry
Supersymmetry Physics Colloquium University of Virginia January 28, 2011 Stephen P. Martin Northern Illinois University 1 The Standard Model of particle physics • The “Hierarchy Problem”: why is the Higgs mass so • small? Supersymmetry as a solution • New particles predicted by supersymmetry • Supersymmetry is spontaneously broken • How to find supersymmetry • 2 The Standard Model of Particle Physics Quarks (spin=1/2): Name: down up strange charm bottom top − 1 2 − 1 2 − 1 2 Charge: 3 3 3 3 3 3 Mass: 0.005 0.002 0.1 1.5 5 173.1 Leptons (spin=1/2): − − − Name: e νe µ νµ τ ντ Charge: −1 0 −1 0 −1 0 Mass: 0.000511 ∼ 0 0.106 ∼ 0 1.777 ∼ 0 Gauge bosons (spin=1): ± 0 Name: photon (γ) W Z gluon (g) Charge: 0 ±1 0 0 Mass: 0 80.4 91.2 0 All masses in GeV. (Proton mass = 0.938 GeV.) Not shown: antiparticles of quarks, leptons. 3 There is a last remaining undiscovered fundamental particle in the Standard Model: the Higgs boson. What we know about it: Charge: 0 Spin: 0 Mass: Greaterthan 114 GeV, and not between 158 and 175 GeV ( in most simple versions) Less than about 215 GeV ( indirect, very fuzzy, simplest model only) Fine print: There might be more than one Higgs boson. Or, it might be a composite particle, made of other more basic objects. Or, it might be an “effective” phenomenon, described more fundamentally by other unknown physics. But it must exist in some form, because... 4 The Higgs boson is the source of all mass. -
The Higgs Boson What Is
The Higgs Boson What is it? The Higgs boson is a hypothesized elementary particle that, if confirmed, would provide the mechanism by which the other elementary particles in the universe have mass. Elementary particles are the smallest fundamental units of matter. We used to think atoms were the smallest, and then we discovered that the atomic nucleus existed and it was made up of two types of subatomic particles, protons and neutrons. We now know that the protons and neutrons are themselves made of elementary particles called quarks. With this discovery, all of the matter around us is made up of quarks and electrons. We have discovered over the last 80 years that electrons are a member of a class of other elementary particles called leptons. We also can divide up elementary particles into two classes, called fermions and bosons, which are defined by a quantum mechanical property know as “spin”. Fermions have half-integral spin (like ½, 3/2, etc.) while bosons have integral spin (like 0, 1, 2, etc.). Quarks and leptons are fermions. We believe that at a quantum level the forces that cause quarks and leptons to attract or repel each other are carried by bosons. The Standard Model (SM) of elementary particle physics is a theory that explains how quarks and leptons interact in terms of three forces: The electromagnetic force, strong nuclear force, and weak nuclear force. The bosons that carry the electromagnetic force are photons. Gluons are the bosons that carry the strong nuclear force, and W and Z bosons carry the weak nuclear force.