The Eighteen Parameters of the Standard Model in Your Everyday Life Twenty-seven The Eighteen Parameters of the Standard Model in Your Everyday Life Robert N. Cahn Lawrence Berkeley National Lab LPNHE juin 2015

A Polemic Asserting that particle physics addresses the question What makes the everyday world the way it is? juin 2015 LPNHE

A Muonic World μ e What happens? Matter shrinks: Light becomes soft x rays. juin 2015 LPNHE

No. Remember muonic atoms. “Muon” would be stable, but “hydrogen” isn’t: Universe = neutrons and neutrinos! juin 2015 LPNHE

Today’s theory has 27 (+1) dials. One is . juin 2015 LPNHE

The dials appear to be independent, arbitrarily set The dials appear to be independent, arbitrarily set. Probably they are linked. juin 2015 LPNHE

Increase u-quark mass by 0.8 MeV hydrogen disappears by only 0.16 MeV and nitrogen disappears: juin 2015 LPNHE

Fundamental Fermions u +2/3 0.005 c +2/3 1.5 t +2/3 172 d -1/3 0.010 0.15 b -1/3 4.5 Electric charge Mass (GeV) e 0 ?  0  0 e -1 0.0005  -1 0.106  -1 1.78 juin 2015 LPNHE

Other worlds As long as the masses of the quarks and leptons appear arbitrary, there are plausible alternative worlds. As long as we don’t understand why there are three generations, we can imagine other possibilities. juin 2015 LPNHE

Suppose we had only the second generation: Only one quark survives: No isotopes. juin 2015 LPNHE

A Strange World One stable baryon: No nuclei? Lightest meson is Probably too heavy to bind to A single atom: juin 2015 LPNHE

18 Parameters Quark masses: Charged lepton masses: Coupling strengths: Quark mixing: Electroweak Symmetry Breaking: juin 2015 LPNHE

mt and the proton’s mass Proton’s mass determined by QCD coupling strength not quark masses. (u and d quark masses are about 1% of a proton’s) If top quark mass were 10 times smaller, the proton’s mass would be reduced by factor 0.84, if we believe in Grand Unification. juin 2015 LPNHE

CP Violation and Baryon-Antibaryon Asymmetry Andrei Sakharov (1967): Why we’re here: Baryon number violation. Non-equilibrium. CP violation. juin 2015 LPNHE

Is there CP violation in leptons? Neutrinos have mass. Neutrinos mix as quarks do. Neutrinos can be their own antiparticles. 1827 3 neutrino masses 4 mixing parameters 2 extra phases if “Majorana neutrinos” juin 2015 LPNHE

Majorana Neutrinos Electron has four degrees of freedom: Massive particle needs L and R. Can’t have just : Can’t use For neutrinos can use (Majorana) juin 2015 LPNHE

Which CP violation makes us happen? Quarks? No. Too small. Light neutrinos? No. Too small. Heavy neutrinos? Maybe! Need more parameters. CP violation for light neutrinos would be hint. juin 2015 LPNHE

GF in your everyday life. drives the sun. Increasing v increases mW and decreases GF Decreases heat at center of sun. Sun contracts. juin 2015 LPNHE

Problem 13.9 Calculate what the sun’s spectrum would be if the mass of the W boson were decreased by a factor of two and what it would be if the mass of the W boson were increased by a factor of two. juin 2015 LPNHE

Solution by J.D.Jackson Doubling would cause the radius to shrink by 33% and increase the surface temperature by 22%. Be sure to use sunblock! juin 2015 LPNHE

What about Higgs boson mass? Doesn’t affect much. That’s why it was so hard to find! There could be several Higgs bosons, as in supersymmetry. juin 2015 LPNHE

Supersymmetry For every particle, there is partner with spin differing by half a unit: Requires at least three neutral,two charged Higgs bosons. quark squark electron selectron gluon gluino juin 2015 LPNHE

Why should we believe in supersymmetry? “Supersymmetry has withstood the test of time, although there is no evidence to support it.” From an introduction for Bruno Zumino as colloquium speaker at Berkeley. Theoretical esthetics. Half the particles required by supersymmetry have been found. Grand unification works with supersymmetry, but not without it. juin 2015 LPNHE

Grand Unification or Not? Standard Model Minimal Supersymmetric Standard Model U(1) U(1) SU(2) SU(2) SU(3) juin 2015 LPNHE

What if the lightest particles were selectrons, that is, bosons? Atoms would lose their individuality. Molecules would lose their integrity. Matter would fuse into an undifferentiated blob. juin 2015 LPNHE

Binding energy of matter For ordinary matter with N atoms For bosonic atoms (F. J. Dyson, 1967) Watch out! juin 2015 LPNHE

It teaches us how much we actually have to explain about the world. The greatness of the Standard Model is not the questions it answers but the questions it lets us ask. It teaches us how much we actually have to explain about the world. It demands that we learn how our world was chosen (by symmetry breaking) from many equally plausible and quite different alternatives. juin 2015 LPNHE

Without addressing the fundamental questions of particle physics we cannot fully explain the world of atoms and molecules, or even why there are atoms and molecules. juin 2015 LPNHE

Extra Slides juin 2015 LPNHE

Coupling Constants: They’re not constant: vacuum polarization: quarks, leptons juin 2015 LPNHE

Grand Unification? We know weak and electromagnetic interactions are one. Can we combine electroweak with strong interactions? If we “evolve” do they converge to a single value? juin 2015 LPNHE

Unification Philosophy High-energy values fixed. Low-energy values of couplings: “evolve” (even in Kansas) not fundamental depend on fermion masses juin 2015 LPNHE

Evolution of em For t quark, Q=2/3. Multiply by 3 for color. juin 2015 LPNHE

If the t quark mass were 17 GeV em would decrease by 0.5% juin 2015 LPNHE

Evolution of strong nf is the number of quark flavors with mass below M. 11 comes from gluon self-interaction. Integration constant sets mass scale. juin 2015 LPNHE

QCD scale depends on mt juin 2015 LPNHE

Weak Decays Cabibbo hypothesis: Discovery of charm quark made this just a rotation: juin 2015 LPNHE

Six Quarks Kobayashi and Maskawa showed that three doublets lead to complex mixing matrix: Only four independent parameters, but still complex. juin 2015 LPNHE

Mixing Amplitudes What if 0.97 had been 0.25? We will see…. M. Kobayashi T. Maskawa 2009 Nobel Prize What if 0.97 had been 0.25? We will see…. Actual elements are complex:  CP violation juin 2015 LPNHE

Neutrino Masses and Mixing Oscillations: “atmospheric” and “solar” neutrinos: 0.06 eV 0.009 eV 0.0 eV e   juin 2015 LPNHE

Electroweak Symmetry Breaking Weak isospin: Breaking this symmetry gives mass to fermions, W, and Z. juin 2015 LPNHE

Higgs Litany To minimize potential energy: 2009 Nobel Prize Three massless bosons eaten to make W+, W-, Z0 massive. Y. Nambu juin 2015 LPNHE

Changing Vud can only decrease. Reducing it to 0.25 is equivalent to doubling . juin 2015 LPNHE