Higgs Boson 1964-2013 Craig Roberts 2 Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 3 9.8-million people 28,120 km2 (10,874 m2) 92% the size of Belgium 349 people/km2 (901/m2) Sited on the south- western shore of Lake Michigan 30 miles 58,030 km2 (22,404m2) Craig Roberts. Laying the God Particle to Rest (95p) 4 University of South Carolina Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 5 0.13-million people 1.3% the population of Chicago 349 km2 (132 m2) 1.2% of the size of Chicago 372 people/km2 (984/m2) 1.1% the pop- density of Chicago Craig Roberts. Laying the God Particle to Rest (95p) 6 University of South Carolina USC is in downtown Columbia Argonne is 30 miles from downtown Chicago Why? Argonne traces its birth from Enrico Fermi's secret charge — the Manhattan Project – to create the world's first self-sustaining nuclear reaction. Code-named the "Metallurgical Lab", the team constructed Chicago Pile-1, which achieved criticality on December 2, 1942, underneath the University of Chicago's Stagg football field stands. Because the experiments were deemed too dangerous to conduct in a major city, the operations were moved to a spot in nearby Palos Hills and renamed “Argonne” after the surrounding forest. Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 7 Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 8 9 Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina NStar 2017 nstar2017.physics.sc.edu/ – Department of Physics and Astronomy, University of South Carolina Conference gathering more than 100 experimentalists and theorists, focused on problems at interface between nuclear & particle physics: This area is called “Hadron Physics” Each year, International Scientific Community devotes as many resources to Hadron Physics as it does to CERN – This is plainly high-profile research USA is now developing plans for construction of a new facility Electron Ion Collider. – Cost: on the order of $1-billion. Begin operation in roughly 10-15 years Our research is helping to develop the scientific and technical case in support of this new construction and operation initiative Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 10 NStar 2017 nstar2017.physics.sc.edu/ – Department of Physics and Astronomy, University of South Carolina Conference gathering more than 100 experimentalists and theorists, focused on problems at interface between nuclear & particle physics: This area is called “Hadron Physics” Each year, International Scientific Community devotes as many resources to Hadron Physics as it does to CERN – This is plainly high-profile research Also … USA has just completed the 10-year $340-million upgrade of the JLab facility (Newport News, Virginia) Research canvassed at NStar17 is a motivation and guide for many experiments at this facility Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 11 Craig Roberts. Laying the God Particle to Rest (95p) 12 University of South Carolina Standard Model - History In the early 20th Century, the only matter particles known to exist were the proton, neutron, and electron. With the advent of cosmic ray science and particle accelerators, numerous additional particles were discovered: o muon (1937), pion (1947), kaon (1947), Roper resonance (1963), … By the mid-1960s, it was apparent that not all the particles could be fundamental. o A new paradigm was necessary. Constituent-quark theory (1964) of Gell-Mann and Zweig, independently, was a critical step forward. o Gell-Mann, Nobel Prize 1969: "for his contributions and discoveries concerning the classification of elementary particles and their interactions". Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 13 Supposed to explain and unify all the forces of Nature, except Gravity Craig Roberts. Laying the God Particle to Rest (95p) 14 University of South Carolina 125 Craig Roberts. Laying the God Particle to Rest (95p) 15 University of South Carolina Craig Roberts. Laying the God Particle to Rest (95p) 16 University of South Carolina Craig Roberts. Laying the God Particle to Rest (95p) 17 University of South Carolina The Standard Model of particle physics lays out the basics of how elementary particles and forces interact in the universe. But the theory crucially fails to explain how particles actually get their mass. Particle physicists believe the Higgs boson gives the particles mass and thus fills one of the key holes in modern physics. Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 18 Higgs Boson Craig Roberts. Laying the God Particle to Rest (95p) 19 University of South Carolina Searching for the God Particle 40 year effort, at facilities around the world 27km (17m) ring Craig Roberts. Laying the God Particle to Rest (95p) 20 University of South Carolina 2013: Higgs and Englert The 2013 Nobel Prize in Physics was awarded to Peter Higgs and Francois Englert following discovery of the Higgs boson at the Large Hadron Collider in 2012. With this discovery the Standard Model of Particle Physics became complete. Its formulation and verification Where to now? are a remarkable story. Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 21 Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 22 Meaning of Mass Energy is Mass Mass is Matter What is the nature of “Matter” in the Standard Model? – Where does it obtain its mass? – What is the origin of its interaction scale? – How is it built from the elementary degrees-of-freedom? Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 23 Matter In classical physics In particle physics, that must change In the Standard Model, at least, elementary particles occupy zero volume In stepping beyond the Standard Model, that will probably change But we can say with certainty that elementary particles occupy very little volume Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 24 Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 25 Higgs Boson The Higgs boson is often said to give mass to everything. Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 26 Higgs Boson The Higgs boson is often said to give mass to everything. However, that is wrong. It only gives mass to some very simple particles: – accounting for only one or two percent of the mass of more complex things like atoms, molecules and everyday objects, from your mobile phone to your pet llama. Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 27 Measuring a particle’s mass Measuring mass is much harder if the particle has no electric charge: one must infer the mass using particle decays Simple example: The mass of a sub-microscopic particle can be measured using classical physics Consider a particle “p” with charge “e” Place p in an electric field. It will accelerate: a = (e/m) E to a given velocity, v, which can be measured Turn on a perpendicular magnetic field, B, and switch off E p will experience a new centripetal force: F = m v2/r = m a = e v × B ⇒ a = (e/m) v × B = v2/r The acceleration is always perpendicular to the velocity, so it forces the path of p to become curved Measure the curvature ⇒ “r”, then m = e r|B|/|v| Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 28 Where does our mass come from? At the first level of approximation, the mass of everything we can see is simply the sum of the masses of all the neutrons and protons contained in the object neutron neutron and proton masses are each 1 GeV (Giga electron volts), i.e. proton approximately 2000 × me Higgs boson produces the electron mass: me But what produces the masses of the neutron and proton? Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 29 Origin of Mass ? The vast majority of mass comes from the energy needed to hold quarks together inside nuclei Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 30 Hadron Physics The vast majority of mass comes from the energy needed to hold quarks together inside nuclei Significant part of the experimental and theoretical research performed in Physics and Astronomy at USC Major focus of the Nstar 17 conference Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 31 Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 32 Quantum Chromodynamics (QCD) Quite possibly, the most remarkable theory we have ever invented One line and two definitions are responsible for the origin, mass and size of all visible matter! Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 33 Quantum Chromodynamics (QCD) Quite possibly, the most remarkable theory we have ever invented One line and two definitions are responsible for the origin, mass and size of all visible matter! Craig Roberts. Laying the God Particle to Rest (95p) University of South Carolina 34 What is Quantum? Inventors of Quantum Mechanics Planck Einstein – Albert Einstein • Nobel Prize for explaining the photoelectric effect Bohr de Broglie – 1905 (prize 1921) • electromagnetic waves → photons • “According to the assumption to be contemplated here, when a light ray is Born Dirac spreading from a point, the energy is not distributed continuously over ever-increasing spaces, but consists of a finite number of 'energy quanta' that are localized in points in space, move without dividing, and can be Heisenberg Pauli absorbed or generated only as a whole.” • 1926 … light quanta first called “photons” … Wolfers (optics) and Lewis (chemist) Schrödinger Feynman Craig Roberts.