String Theory in the LHC Era J Marsano (marsano@uchicago.edu) 1 Tuesday, May 1, 12
String Theory in the LHC Era 1. Electromagnetism and 5. Physics Beyond the Standard Model Special Relativity and Supersymmetry 2. The Quantum World 6. Einstein’s Gravity 3. Why do we need the Higgs? 7. Why is Quantum Gravity so Hard? 4. The Standard Model 8. String Theory and Unification 9. String Theory and Particle Physics 2 Tuesday, May 1, 12
The Standard Model of Particle Physics Electromagnetism Quarks Strong nuclear force Leptons Weak nuclear (electrons and force neutrinos) 3 Tuesday, May 1, 12
http://mblogs.discovermagazine.com/cosmicvariance/ Hat tip R Lipscomb 4 2012/04/25/what-particle-are-you/ Tuesday, May 1, 12
Quantum Electrodynamics Weak Nuclear Force Massless force carrier Weak bosons W ± , Z 0 Photon γ Massive force carriers Long range force Short range force γ e − e − 1 Range set by Mass of W ± , Z 0 e − p + e − n W − Quantum Chromodynamics e − Many massless force carriers Gluons g ν e q Strongly coupled at long distances q g q q 5 Tuesday, May 1, 12
The Standard Model of Particle Physics Electromagnetism Quarks Strong nuclear force Leptons Weak nuclear (electrons and force neutrinos) + Higgs Boson All particle masses from coupling to Higgs 6 Tuesday, May 1, 12
The Standard Model of Particle Physics Electromagnetism Photon massless long range force Quarks Strong nuclear Gluons massless but many force of them → confinement Leptons W and Z bosons massive Weak nuclear (electrons and force short range force neutrinos) Quark and lepton + Higgs Boson masses from Higgs All particle masses from coupling to Higgs 6 Tuesday, May 1, 12
Beyond the Standard Model Why? 7 Tuesday, May 1, 12
Standard Model doesn’t incorporate gravity More on this in the remaining lectures..... 8 Tuesday, May 1, 12
Grand Unification Inverse electromagnetic coupling Inverse weak interaction coupling Inverse QCD coupling F. Wilczek, Nature 433 , 239 Grand Unified Theory (GUT) that gives common origin to the three forces of the Standard Model? 9 Tuesday, May 1, 12
Beyond the Standard Model Why? 1. Dark Matter We will focus on two additional reasons: 2. Hierarchy Problem 10 Tuesday, May 1, 12
1. Dark Matter 11 Tuesday, May 1, 12
Dark Matter Fritz Zwicky Stars near the edge of galaxies are rotating faster than they should New ‘dark matter’ contributes to the gravitational field that accelerates the stars 12 Tuesday, May 1, 12
Gravitational Lensing Can ‘see’ dark matter more directly Tuesday, May 1, 12
Gravitational Lensing Can ‘see’ dark matter more directly Tuesday, May 1, 12
Dark Matter also affects the Cosmic Microwave Background Key component of standard cosmology What does this mean for particle physics? Tuesday, May 1, 12
Standard cosmology: Dark Matter is a WIMP Weakly Interacting Massive Particle Couples to the weak interactions not to electromagnetism or the strong interaction Tuesday, May 1, 12
Standard cosmology: Dark Matter is a WIMP Weakly Interacting Massive Particle Couples to the weak interactions Must be stable or have lifetime longer than the age of the universe (~ 10 billion years) not to electromagnetism or the strong interaction Tuesday, May 1, 12
Standard cosmology: Dark Matter is a WIMP Weakly Interacting Massive Particle Couples to the weak interactions Must be stable or have lifetime longer than the age of the universe (~ 10 billion years) not to electromagnetism or the strong interaction There is no particle like this in the Standard Model Tuesday, May 1, 12
There is no particle like this in the Standard Model ...but good reason to see it soon Early universe Dark matter in ‘thermal equilibrium’ Standard Model Standard Model Dark Matter Dark Matter Particles Particles Particles Particles Standard Model particles collide Dark matter particles annihilate to make dark matter back to Standard Model Tuesday, May 1, 12
There is no particle like this in the Standard Model ...but good reason to see it soon Standard Model Standard Model Dark Matter Dark Matter Particles Particles Particles Particles Tuesday, May 1, 12
There is no particle like this in the Standard Model ...but good reason to see it soon Standard Model Standard Model Dark Matter Dark Matter Particles Particles Particles Particles As the universe expands, these reactions stop Roughly, particles too far apart for them to continue annihilating Tuesday, May 1, 12
There is no particle like this in the Standard Model Rate at which dark matter annihilates ...but good reason to see it soon into Standard Model particles h σ v i ⇠ m 2 1 Dark Ω Dark ⇠ g 4 Dark matter density Tuesday, May 1, 12
There is no particle like this in the Standard Model Rate at which dark matter annihilates ...but good reason to see it soon into Standard Model particles h σ v i ⇠ m 2 1 Dark Ω Dark ⇠ g 4 Dark matter density ∼ 0 . 1 for WIMP with m Dark ∼ 100 GeV Tuesday, May 1, 12
There is no particle like this in the Standard Model Rate at which dark matter annihilates ...but good reason to see it soon into Standard Model particles h σ v i ⇠ m 2 1 Dark Ω Dark ⇠ g 4 Observed value Dark matter density ∼ 0 . 1 for WIMP with m Dark ∼ 100 GeV Tuesday, May 1, 12
There is no particle like this in the Standard Model Rate at which dark matter annihilates ...but good reason to see it soon into Standard Model particles h σ v i ⇠ m 2 1 Dark Ω Dark ⇠ g 4 Observed value Dark matter density ∼ 0 . 1 for WIMP with m Dark ∼ 100 GeV Mass scales probed at the LHC Tuesday, May 1, 12
There is no particle like this in the Standard Model Rate at which dark matter annihilates ...but good reason to see it soon into Standard Model particles h σ v i ⇠ m 2 1 Dark Ω Dark ⇠ g 4 Observed value Dark matter density ∼ 0 . 1 for WIMP with m Dark ∼ 100 GeV Mass scales probed at the LHC The ‘WIMP Miracle’ Tuesday, May 1, 12
Get the right (observed) amount of dark matter if we assume it is A WIMP with mass ~100-1000 GeV ~ Electroweak scale! Tuesday, May 1, 12
The ‘WIMP Miracle’ Get the right (observed) amount of dark matter if we assume it is A WIMP with mass ~100-1000 GeV ~ Electroweak scale! Tuesday, May 1, 12
Dark Matter Searches Direct Detection Indirect Detection Look for signs of dark matter Look for dark matter colliding annihilation in the sky with heavy nuclei (Ge, I, Xe, ...) Tuesday, May 1, 12
Direct Detection DAMA and CoGent see something but nobody else does Tuesday, May 1, 12
Indirect Detection Fermi Satellite Evidence for 130 GeV dark matter annihilation in galactic center? waiting for official analysis from Fermi/LAT collaboration C Weniger arXiv:1204.2797 Tuesday, May 1, 12
2. Hierarchy Problem 23 Tuesday, May 1, 12
Hierarchy Problem Energy Scales 10 18 GeV Quantum gravity 16 orders of magnitude Where did this large scale separation come from? 10 2 GeV Weak scale Higgs boson breaks electroweak symmetry Generates mass for W and Z bosons Proton mass 1 GeV 10 − 3 GeV Electron mass 24 Tuesday, May 1, 12
Hierarchy Problem Energy Scales 10 18 GeV Quantum gravity 16 orders of magnitude Where did this large scale separation come from? Why do we care? 10 2 GeV Weak scale Higgs boson breaks electroweak symmetry Generates mass for W and Z bosons Proton mass 1 GeV 10 − 3 GeV Electron mass 24 Tuesday, May 1, 12
Energy Electroweak Hierarchy 10 18 GeV Quantum gravity 16 orders of magnitude Scale of electroweak symmetry breaking determined by Higgs physics Higgs boson breaks 10 2 GeV Weak scale electroweak symmetry Generates mass for W and Proton mass 1 GeV Z bosons 10 − 3 GeV Electron mass Potential for Higgs field sets the scale of the ‘Higgs bath’ Determined by quantum effects 25 Tuesday, May 1, 12
Energy Electroweak Hierarchy 10 18 GeV Quantum gravity 16 orders of magnitude Higgs boson breaks 10 2 GeV Weak scale electroweak symmetry Generates mass for W and Proton mass 1 GeV Z bosons 10 − 3 GeV Electron mass t Many important contributions, including top loop h h t 26 Tuesday, May 1, 12
Energy Electroweak Hierarchy 10 18 GeV Quantum gravity 16 orders of magnitude Higgs boson breaks 10 2 GeV Weak scale electroweak symmetry Generates mass for W and Proton mass 1 GeV Z bosons 10 − 3 GeV Electron mass t Many important contributions, including top loop h h t = ∞ (Infinity)! 26 Tuesday, May 1, 12
t h h = ∞ (Infinity)! t Quantum Field Theory generates many infinities General Rule: 27 Tuesday, May 1, 12
t h h = ∞ (Infinity)! t Quantum Field Theory generates many infinities Quantum Field Theory is smarter than we are General Rule: If we get an infinite answer then we must have done something wrong 27 Tuesday, May 1, 12
Quantum Field Theory is t smarter than we are h h If we get an infinite answer then we must have done something wrong t Ok so what are we doing wrong? 28 Tuesday, May 1, 12
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