Download presentation

Presentation is loading. Please wait.

Published byVictoria Payne Modified over 5 years ago

1
The Higgs boson What it is: 1) barroom explanation 2) more, with some pictures 3) yet more, with some formulas Plus pictures related to the discovery John Donoghue July 10, 2012

2
1) A Higgs boson walk into a bar…

3
Basic points: -In fundamental theory without Higgs, all particles travel at speed of light -Higgs is like molasses filling space – slows them down -gives them mass Significance – completes our fundamental theory (SM) - without Higgs – no atoms, no stars …..

4
1) A Higgs boson walk into a bar… And the atmosphere gets heavy… He walks out and everyone falls apart…

5
What are we trying to explain? 2MASS =UMass +

6
The reductionists Universe: The Standard Model = with gauge group SU(3)xSU(2) L xU(1) and 3 generations

7
Basic features in words: 1)Fundamental particles: World Atoms Nuclei Quarks and Leptons 2) Fundamental forces/fields: Strong – holds nuclei together Electroweak – Electricity, Magnetism + atomic forces, light,.... Gravity – structure of universe at large scales

8
Relevant fact: 26 parameters m e = e v = 0.511 MeV m = v = 105 MeV m = v =1750 MeV m u = u v = 4 MeV m d = d v = 7 MeV m s = s v = 150 MeV m c = c v = 1500 MeV m b = b v = 5000 MeV m t = t v = 175,000 MeV m e = e v = 0.511 MeV m = v = 105 MeV m = v =1750 MeV m u = u v = 4 MeV m d = d v = 7 MeV m s = s v = 150 MeV m c = c v = 1500 MeV m b = b v = 5000 MeV m t = t v = 175,000 MeV v = 246,000 MeV L=(10 -9 MeV) 4 M W =g w 2 v= 81,000 MeV m H 2 = v 2 = 125,000 MeV V us =0.22 V cb = 0.04 V ub = 0.002 etc. = e 2 /ħc = 1/137 w = 1/25 s = 1 M PL = 1/G 1/2 = 10 22 MeV

9
Also tied to symmetry breaking

10
Symmetry in the fundamental interactions: Early on, evidence of hidden symmetry found: - electron related to neutrino - up quark and down quark related - W, Z related - but masses break the symmetry There is mathematics of group theory at work - SM = SU(3) x SU(2) x U(1) But symmetry seems broken or hidden Little advertised fact: theory start with four Higgs bosons - all equivalent due to symmetry

11
The Higgs vacuum expectation value Standard Model relies on symmetry breaking of Higgs scalar V( H ) By 1960s, people had found approximate symmetries in the interactions - would be exact symmetries if masses were zero Higgs mechanism – energetics to break symmetry

12
Logic of symmetry breaking and mass generation Basic theory has symmetry and massless particles Higgs sector shares these properties, but Energetics favor solution with a constant field everywhere This then breaks symmetry In this background field, particles have mass Including Higgs itself

13
Now some equations: Electricity and magnetism and photons: Particle with mass: Particle with Higgs

14
The Higgs mechanism : Minimize energy Source term now becomes mass term Excitation around constant field is Higgs particle

15
Large Hadron Collider (LHC) at CERN: Finding the Higgs

16
UMass participates on the ATLAS experiment

18
How one sees a Higgs boson:

19
Another decay process:

20
Discovery significance

21
Is it really the SM Higgs?

22
The Nobel dilemma: My bet: Higgs, Englert and Brout

Similar presentations

Presentation is loading. Please wait....

OK

Richard Kenway Everything is a computer Richard Kenway.

Richard Kenway Everything is a computer Richard Kenway.

© 2019 SlidePlayer.com Inc.

All rights reserved.

To make this website work, we log user data and share it with processors. To use this website, you must agree to our Privacy Policy, including cookie policy.

Ads by Google