A Scientific Saga
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Spontaneous Electroweak Symmetry Breaking
Arianna Borrelli Who broke electroweak symmetry? Who broke electroweak symmetry? This question may sound rather naive, yet the discourse about the “spontaneous” breaking of electroweak symmetry entails a reference to agency which finds implicit expression in the often repeated (and equally often criticized) statement that the particles of the Standard Model “acquire” their mass “thanks to” the Higgs boson. The implicit agency manifests itself in its most extreme form in the nickname happily bestowed on the Higgs boson in the popular press: “the God particle”. The construction of spontaneous symmetry breaking can be analysed as the interplay between different mathematical formalisms, phenomena of various nature and verbal statements connecting the whole and endowing it with physical meaning. One may argue that the latter, verbal component played a key role in the development of the notion of spontaneous symmetry breaking, spinning a narrative which allowed to close gaps in mathematical arguments and downplay the arbitrariness of analogies between phenomena. From this process emerged an ambiguous mathematical-physical notion which was to become the symbolic carrier of a “mechanism of mass generation”. In the papers quoted as the origin of spontaneous symmetry breaking Yoshiro Nambu and Giovanni Jona Lasinio used an analogy to super-conductive systems to interpret the masses of strongly interacting particles as expression of an exact, but hidden symmetry (N 1960, N/JL 1961). They did not speak of “symmetry breaking” - let alone a “spontaneous” one - but rather of the existence of “superconductor solutions” to the equations for particle self-energy. Jeffrey Goldstone (1961) reformulated their arguments in terms of an elementary scalar field with non-zero vacuum expectation value, but it was Marshall Baker and Sheldon Glashow (1962) who framed the issue as “spontaneous symmetry breaking”, attempting to explain mass values in terms of “stable self-generated solution” of quantum-field-theoretical equations. -
From Leon Lederman, the God Particle (Last Reading Continued)
18 From Leon Lederman, The God Particle (last reading continued) …. DEMOCRITUS: I have trouble with emptiness. How do I describe it? If it is truly nothing, then how can it exist? My hands touch your desk here. On the way to the desk top, my palm feels the gentle rush of air that fills the void between me and the desk's surface. Yet air cannot be the void itself, as Empedocles so ably pointed out. How can I imagine my atoms if I cannot feel the void in which they must move? And yet, if I want to somehow account for the world by atoms, I must first define something that seems to be undefinable because it is devoid of properties. LEDERMAN: So what did you do? DEMOCRITUS [laughing]: I decided not to worry. I a-voided the issue. LEDERMAN: Oi Vay! DEMOCRITUS: Sorry. Seriously, I solved the problem with my knife. LEDERMAN: Your imaginary knife that cuts cheese into atoms? DEMOCRITUS: No, a real knife, cutting, say, a real apple. The blade must find empty places where it can penetrate. LEDERMAN: What if the apple is composed of solid atoms, packed together with no space? DEMOCRITUS: Then it would be impenetrable, because atoms are impenetrable. No, all matter that we can see and feel is cuttable if you have a sharp enough blade. Therefore the void exists. But mostly I said to myself back then, and I believe it still, that one must not forever be stalled by logical impasses. We go on, we continue as if nothingness can be accepted. -
Furukawa's Technology Contributed to the Discovery of the Higgs Boson
Furukawa Here and There Special About the Furukawa’s technology Higgs boson contributed to the discovery It is an elementary particle, which is the smallest unit in nature. Modern of the Higgs boson physics considers that all phenomena n July 4, the discovery of the Higgs boson in the natural world can be explained called “God particle” received extensive in 17 elementary particles. Discovery of O century? coverage in the press. The European Council Sixteen of the 17 particles, including for Nuclear Research (Conseil Européen pour la What’s so great those that constitute substances about it? Recherche Nucléaire: CERN), headquartered in and those that transmit forces, had Geneva, Switzerland, announced the discovery of a already been discovered. Only the new particle that it deemed to be the Higgs boson, Higgs boson, which functions to which for many years has been the target of a search provide mass (weight) to substances, by physicists around the world. Furukawa Electric had remained unidentified. contributed significantly to what some are calling the discovery of the century. The Higgs boson is referred to as the “God particle” because it has a significant role in the formation of the universe and substances. This made it easier for The birth of the universe elementary particles with Speed mass to gather. Some of Elementary particle Elementary particle of I feel these particles stuck to one light! Higgs boson something another to form the origin of heavy atoms. This is how the Earth, all substances in the universe I see. and humankind are believed to have originated. It is said that if it were no Higgs boson, the human body would be torn apart in one billionth of a second. -
The Weak Charge of the Proton Via Parity Violating Electron Scattering
The Weak Charge of the Proton via Parity Violating Electron Scattering Dave “Dawei” Mack (TJNAF) SPIN2014 Beijing, China Oct 20, 2014 DOE, NSF, NSERC SPIN2014 All Spin Measurements Single Spin Asymmetries PV You are here … … where experiments are unusually difficult, but we don’t annoy everyone by publishing frequently. 2 Motivation 3 The Standard Model (a great achievement, but not a theory of everything) Too many free parameters (masses, mixing angles, etc.). No explanation for the 3 generations of leptons, etc. Not enough CP violation to get from the Big Bang to today’s world No gravity. (dominates dynamics at planetary scales) No dark matter. (essential for understanding galactic-scale dynamics) No dark energy. (essential for understanding expansion of the universe) What we call the SM is only +gravity part of a larger model. +dark matter +dark energy The astrophysical observations are compelling, but only hint at the nature of dark matter and energy. We can look but not touch! To extend the SM, we need more BSM evidence (or tight constraints) from controlled experiments4 . The Quark Weak Vector Charges p Qw is the neutral-weak analog of the proton’s electric charge Note the traditional roles of the proton and neutron are almost reversed: ie, neutron weak charge is dominant, proton weak charge is almost zero. This suppression of the proton weak charge in the SM makes it a sensitive way to: 2 •measure sin θW at low energies, and •search for evidence of new PV interactions between electrons and light quarks. 5 2 Running of sin θW 2 But sin θW is determined much better at the Z pole. -
In Search of the God Particle
Tomorrow - What Lies Beyond the Horizon The God Particle Weizmann Institute of Science by Eilam Gross In Search of the God Particle By Eilam Gross The extraordinary experiment being conducted in CERN (the European Organization for Nuclear Research), in Switzerland, aspires to bring us closer than ever to the moment of Creation – the Big Bang, when the elementary particles making up the Universe were created. Billions of dollars have been invested into this quest to find out where we come from and where we are going. About 14 billion years ago – 13.7 to be precise – the Universe was born. It emerged from a singular, energy-laden point in an event we know as the Big Bang. An updated Bible would begin with the verse: “In the beginning there was nothing. And God said: Let there be light. And there was a Big Bang, and there was space and there was time, and there was the space-time.” At the moment, no one knows what really happened during that initial infinitesimal fraction of a second of creation. We are quite certain though, that the immense energy of that moment gave rise to the conditions necessary for the creation of matter and forces, thus initiating a long process that eventually led to the existence of humans with the ability to apply our intelligence to deciphering the elements that are the building blocks of our own creation. In 1900, 108 years ago and almost 14 billion years after the Big Bang, a 76- year-old Lord William Thomson Kelvin stood in an auditorium filled to bursting in the British Royal Society and gave one of the most famous lectures in the history of physics. -
TRIUMF & Canadian Scientists Help Measure Proton's Weak Charge
Canada’s national laboratory for particle and nuclear physics Laboratoire national canadien pour la recherche en physique nucléaire et en physique des particules News Release | For Immediate Release | 17 Sep 2013, 5:00 p.m. PDT TRIUMF & Canadian Scientists Help Measure Proton’s Weak Charge (Newport News, VA, USA) --- An international team including Canadian researchers at TRIUMF has reported first results for the proton’s weak charge in Physical Review Letters (to appear in the October 18, 2013 issue) based on precise new data from Jefferson Laboratory, the premier U.S. electron-beam facility for nuclear and particle physics in Newport News, Virginia. The Q-weak experiment used a high-energy electron beam to measure the weak charge of the proton—a fundamental property that sets the scale of its interactions via the weak nuclear force. This is distinct from but analogous to its more familiar electric charge (Q), hence, the experiment’s name: ‘Q-weak.’ Following a decade of design and construction, Q-weak had a successful experimental run in 2010–12 in Hall C at Jefferson Laboratory. Data analysis has been underway ever since. “Nobody has ever attempted a measurement of the proton’s weak charge before,” says Roger Carlini, Q- weak’s spokesperson at Jefferson Laboratory, “due to the extreme technical challenges to reach the required sensitivity. The first 4% of the data have now been fully analyzed and already have an important scientific impact, although the ultimate sensitivity awaits analysis of the complete experiment.” The first result, based on Q-weak’s commissioning data set, is Q_W^p= 0.064 ± 0.012. -
Neutrino Masses-How to Add Them to the Standard Model
he Oscillating Neutrino The Oscillating Neutrino of spatial coordinates) has the property of interchanging the two states eR and eL. Neutrino Masses What about the neutrino? The right-handed neutrino has never been observed, How to add them to the Standard Model and it is not known whether that particle state and the left-handed antineutrino c exist. In the Standard Model, the field ne , which would create those states, is not Stuart Raby and Richard Slansky included. Instead, the neutrino is associated with only two types of ripples (particle states) and is defined by a single field ne: n annihilates a left-handed electron neutrino n or creates a right-handed he Standard Model includes a set of particles—the quarks and leptons e eL electron antineutrino n . —and their interactions. The quarks and leptons are spin-1/2 particles, or weR fermions. They fall into three families that differ only in the masses of the T The left-handed electron neutrino has fermion number N = +1, and the right- member particles. The origin of those masses is one of the greatest unsolved handed electron antineutrino has fermion number N = 21. This description of the mysteries of particle physics. The greatest success of the Standard Model is the neutrino is not invariant under the parity operation. Parity interchanges left-handed description of the forces of nature in terms of local symmetries. The three families and right-handed particles, but we just said that, in the Standard Model, the right- of quarks and leptons transform identically under these local symmetries, and thus handed neutrino does not exist. -
Books 15-6Mx
book reviews very existence of the observable Universe to understand if it were not universally depends upon the spontaneous manifesta- chiral. tion of asymmetry, the phenomenon physi- I personally think it a great pity that Close cists call ‘broken symmetry’. Close focuses, at did not tell the story of broken symmetry as it first, on two discrete broken symmetries: the really happened, because it is a heartening universal ‘handedness’ of life — its left–right story of one of those rare periods when the asymmetry — and the cosmic preference for fragmentation of theoretical physics into matter over antimatter. In the final chapters, condensed-matter, nuclear and particle he goes on to expound the broken continu- branches was temporarily healed and we ous symmetry that is behind the unification were all consciously working together in of weak and electromagnetic interactions. exploring the many quantum consequences It is hard to judge how accessible the lay- of the idea of broken symmetry. man will find tutorial explication of the sort These consequences are as far-reaching contained in this book. For instance, it’s not and as intellectually stimulating in con- clear to me why Stephen Hawking’s writing densed matter as in particle physics, and in seems to be comprehensible, or at least not discussing them Close reveals a definite acceptable, to the layman; I would judge bias in favour of the ‘clean machines’ of par- Close to be much more accessible. So, to my ticle physics as opposed to the mundane limited sense of these things, this should be a complications of condensed matter. -
The Search for Supersymmetry
The Search for Supersymmetry • Introduction the Standard Model of Particle Physics • Introduction to Collider Physics • Successes of the Standard Model • What the Standard Model Does Not Do • Physics Beyond the Standard Model • Introduction to Supersymmetry • Searching for Supersymmetry • Dark Matter Searches • Future Prospects • Other Scenarios • Summary Peter Krieger, Carleton University, August 2000 Force Unifications Standard Model does NOT account magnetism for gravitational interactions Maxwell electromagnetism electricity electroweak S T A Planck Scale (or Planck Mass) weak interactions N D A is defined as the energy scale at R GUT D which gravitational interactions M O become of the same strength as D E SM interactions strong interactions L TOE celestial movement gravitation Newton terrestrial movement - - - MEW MGUT Mplanck The Standard Model Describes the FUNDAMENTAL PARTICLES and their INTERACTIONS All known FORCES are mediated by PARTICLE EXCHANGE a a Effective strength of an interaction depends on X • the coupling strength at the vertex αα • the mass of the exchanged particle MX a a Force Effective Strength Process Strong 100 Nuclear binding Electromagnetic 10-2 Electron-nucleus binding Weak 10-5 Radioactive β decay The Standard Model SPIN-½ MATTER PARTICLES interact via the exchange of SPIN-1 BOSONS MATTER PARTICLES – three generations of quarks and leptons |Q| m < m < m ⎛ e ⎞ ⎛ µ ⎞ ⎛ τ ⎞ 1 e µ τ Mass increases with generation: ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ m = 0 ⎜ ⎟ ⎜ν ⎟ ⎜ ⎟ ν ⎝ν e ⎠ ⎝ µ ⎠ ⎝ν τ ⎠ 0 Mu,d ~ 0.3 GeV ⎛u⎞ ⎛c⎞ ⎛ t ⎞ 2 ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ 3 Each quark comes in 1 three ‘colour’ changes Mt ~ 170 GeV ⎝d⎠ ⎝s⎠ ⎝b⎠ 3 GAUGE BOSONS – mediate the interaction of the fundamental fermions γ 1 Gauge particle of electromagnetism (carries no electric charge) W ± ,Z 0 3 Gauge particles of the weak interaction (each carries weak charge) g 8 Gauge particles of the strong interaction (each gluon carries a colour and an anti-colour charge charge) All Standard Model fermions and gauge bosons have been experimentally observed There is one more particle in the SM – the Higgs Boson. -
The God Particle: If the Universe Is the Answer, What Is the Question?
[PDF] The God Particle: If The Universe Is The Answer, What Is The Question? Dick Teresi, Leon Lederman - pdf download free book The God Particle: If The Universe Is The Answer, What Is The Question? PDF Download, The God Particle: If The Universe Is The Answer, What Is The Question? Download PDF, Read Best Book Online The God Particle: If The Universe Is The Answer, What Is The Question?, The God Particle: If The Universe Is The Answer, What Is The Question? Free Read Online, full book The God Particle: If The Universe Is The Answer, What Is The Question?, free online The God Particle: If The Universe Is The Answer, What Is The Question?, Download PDF The God Particle: If The Universe Is The Answer, What Is The Question?, pdf free download The God Particle: If The Universe Is The Answer, What Is The Question?, the book The God Particle: If The Universe Is The Answer, What Is The Question?, Read Best Book Online The God Particle: If The Universe Is The Answer, What Is The Question?, Read Online The God Particle: If The Universe Is The Answer, What Is The Question? E-Books, Read The God Particle: If The Universe Is The Answer, What Is The Question? Online Free, Read The God Particle: If The Universe Is The Answer, What Is The Question? Full Collection, The God Particle: If The Universe Is The Answer, What Is The Question? PDF read online, The God Particle: If The Universe Is The Answer, What Is The Question? pdf read online, The God Particle: If The Universe Is The Answer, What Is The Question? PDF Download, The God Particle: If The Universe -
Weak Interactioninteraction
WeakWeak InteractionInteraction OutlineOutline Introduction to weak interactions Charged current (CC) interactions Neutral current (NC) Weak vector bosons W± and Z0 Weak charged interactions Beta decay Flavour changing charged current W± boson propagator Fermi coupling constant Parity violation Muon decay Decay rate /lifetime Lepton Universality W± boson couplings for leptons Tau decays Weak quark decays W± boson couplings for quarks Cabibbo angle, CKM mechanism Spectator model Nuclear and Particle Physics Franz Muheim 1 IntroductionIntroduction Weak Interactions Account for large variety of physical processes Muon and Tau decays, Neutrino interactions Decays of lightest mesons and baryons Z0 and W± boson production at √s ~ O(100 GeV) Natural radioactivity, fission, fusion (sun) Major Characteristics Long lifetimes Small cross sections (not always) “Quantum Flavour Dynamics” Charged Current (CC) Neutral Current (NC) mediated by exchange of W± boson Z0 boson Intermediate vector bosons MW = 80.4 GeV ± 0 W and Z have mass MZ = 91.2 GeV Self Interactions of W± and Z0 also W± and γ Nuclear and Particle Physics Franz Muheim 2 BetaBeta DecayDecay Weak Nuclear Decays See also Nuclear Physics Recall β+ = e+ β- = e- Continuous energy spectrum of e- or e+ Î 3-body decay, Pauli postulates neutrino, 1930 Interpretation Fermi, 1932 Bound n or p decay − n → pe ν e ⎛ − t ⎞ N(t) = N(0)exp⎜ ⎟ ⎝ τ n ⎠ p → ne +ν (bound p) τ n = 885.7 ± 0.8 s e 32 τ 1 = τ n ln 2 = 613.9 ± 0.6 s τ p > 10 y (p stable) 2 Modern quark level picture Weak charged current mediated -
Supersymmetry Lecture Notes for FYS5190/FYS9190
Supersymmetry Lecture notes for FYS5190/FYS9190 Paul Batzing and Are Raklev December 4, 2015 2 Contents 1 Introduction 7 2 Groups and algebras 9 2.1 Whatisagroup?.................................. 9 2.2 Representations................................. 12 2.3 Liegroups...................................... 13 2.4 Liealgebras..................................... 15 2.5 Exercises ...................................... 16 3 The Poincar´ealgebra and its extensions 19 3.1 TheLorentzGroup................................. 19 3.2 ThePoincar´egroup ............................... 20 3.3 The Casimir operators of the Poincar´egroup . ........ 20 3.4 The no-go theorem and graded Lie algebras . ...... 22 3.5 Weylspinors .................................... 23 3.6 The Casimir operators of the super-Poincar´ealgebra . ............ 25 3.7 Representations of the superalgebra . ....... 26 3.8 Exercises ...................................... 28 4 Superspace 31 4.1 Superspacecalculus .............................. 31 4.2 Superspacedefinition.. .. .. .. .. .. .. .. 33 4.3 Covariantderivatives. 35 4.4 Superfields ..................................... 35 4.4.1 Scalarsuperfields.............................. 36 4.4.2 Vectorsuperfields. .. .. .. .. .. .. .. .. 37 4.5 Supergauge ..................................... 38 4.6 Exercises ...................................... 39 5 Construction of a low-energy SUSY Lagrangian 41 5.1 Supersymmetry invariant Lagrangians . ....... 41 5.2 Albaniangaugetheories . 42 5.3 Non-Abelian gauge theories . 43 5.4 Supersymmetricfieldstrength.