Particle Physics and LHC Physics David Krofcheck Canterbury Teachers Workshop July 18 th D. KrofcheckCanterbury Teachers Workshop1

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The CMS detector at the Large Hadron Collider Muon Barrel Tracker (Pixels and Strips) EM Calorimeter Hadron Calorimeter Muon Endcaps Forward Calorimeter Beam Scintillator Counters CASTOR ZDC D. Krofcheck Pitt/CMU July New Zealand

D. Krofcheck Pitt/CMU July The really important CMS detectors

Aristotle : all matter is made up of various combinations of Earth, air, fire and water What is matter? This belief about the nature of matter lasted for 2000 years solids liquids gases change D. KrofcheckCanterbury Teachers Workshop6

Democritus Lucretius John Dalton Development of the Atomic Theory Aristotle D. KrofcheckCanterbury Teachers Workshop7

Ideas about Atoms 1800’s John Dalton – meteorologist and teacher - successfully explained chemical reactions by proposing all matter is made up of atoms. - BUT they had no direct evidence! D. KrofcheckCanterbury Teachers Workshop8

Dmitri Mendeleev Russian Periodic Table Similar chemical properties D. KrofcheckCanterbury Teachers Workshop9

Periodic Table ? Atoms Rutherford (1909) Bohr (1913) D. KrofcheckCanterbury Teachers Workshop10

... proton neutron electron Are these the elementary particles, ? Are they composed of even more elementary particles?? Particle and Nuclear Physics are the studies to answer this question D. KrofcheckCanterbury Teachers Workshop11

Matter Particles 1932p, n, e ν 1937 μ 1940s mesons π, K 1950s particles Λ, Δ, Σ,... …hundreds of new particles were discovered! D. KrofcheckCanterbury Teachers Workshop12

In 1964 the idea of quarks was proposed… quarks u d u proton d u d neutron Gell-Mann Zweig These were elementary particle of, fractional electric charge, different flavours D. KrofcheckCanterbury Teachers Workshop13

What is the composition of the proton du u q(u) = +2/3 q(d) = -1/3 q(p) = +1...and of the neutron du d q(n) = -1/3 - 1/3 + 2/3= 0 D. KrofcheckCanterbury Teachers Workshop14

What glues the quarks together? u u d proton Gluons, of course D. KrofcheckCanterbury Teachers Workshop15

Elementary particles of matter 1st family: u, d, e -, e 2nd family: c, s,  -,  3rd family: t, b,  -,  leptons Higgs 4 July, 2012 D. KrofcheckCanterbury Teachers Workshop16

Antimatter Every particle has its antiparticle, of the same mass but opposite quantum numbers eg. electron, e - : q(e - ) =-1, spin = - 1/2, m (e - ) = 9.1  gr. positron, e + : q(e + ) =+1, spin = + 1/2, m (e + ) = 9.1  gr. D. KrofcheckCanterbury Teachers Workshop17

Electromagnetic ForceGravitational Force Strong Colour ForceWeak Force átomo nuclei n  p + e - + e d  u + e - + e All these interactions are manifestations of only 4 basic interactions

Interaction Type Electromagnetic γ (photon) Strong g (gluon) Weak bosons W, Z Gravitational G (graviton) Still not detected experimentally Mediating Particle

Example: Electromagnetic interaction

The Fundamental Interactions are produced by the exchange of a particle mediator The particles of matter interact across a distance by exchanging a “messenger” particle The interaction range decreases as the mass of the messenger particle increases.

Standard Model of Particle Physics In a quantum description of matter and the laws of interaction between them still do not know how to incorporate gravitation, but the rest of interactions are well described by a mathematical theory, the Standard Model, able to make predictions that have been confirmed in experiments. leptons Messengers interactions

Standard Model (~1980) Components of matter Interactions Symmetry This model requires that the particle messengers are massless, But the W and Z are very heavy!!  problem of the origin of mass

Higgs Boson The British physicist Dr. Peter Higgs proposed (1964) the so-called Higgs mechanism: All the particles would be generated in the Big Bang without mass, but by interacting with the field created by the Higgs particle, the particles would acquire mass, the greater, the greater the interaction. This field would fill the whole universe. Interaction with the Higgs field Friction with a viscous liquid ≡

Higgs Boson The British physicist Dr. Peter Higgs proposed (1964) the so-called Higgs mechanism: All the particles would be generated in the Big Bang without mass, but by interacting with the field created by the Higgs particle, the particles would acquire mass, the greater, the greater the interaction. This field would fill the whole universe. Unico “Higgs” observado hasta ahora en un experimento…el propio Dr. Higgs!! Friction with a viscous liquid ≡ Interaction with the Higgs field

Higgs Boson ≡. A recent view of a Higgs at the CMS experiment Th is particle predicted has not yet been unambiguously detected in experiments, hopefully we are hot on the trail!

!!?? H  Z 0 Z 0  μ + μ - μ + μ -

Gauge Bosons – Z 0 First detection in HI collisions! First step is to find Z 0 bosons in PbPb collisions Z 0 → μ + μ - observed for the first time in HI collisions!

29 Z 0 → e + e - observed for the first time in HI collisions! Z 0 → e + e - event candidate

lead + lead collisions may liberate quarks

Jet production in pp collisions jet-jet correlation in QCD “vacuum” D. KrofcheckDijet Probes of Hot Nuclear Matter at the LHC31 Jet

Jet production in PbPb collisions jet-jet correlation in QCD “medium” γ – jet correlation to probe the medium? D. KrofcheckDijet Probes of Hot Nuclear Matter at the LHC32

E-ΔΕ 1 E-ΔΕ 2 Dijet imbalance in PbPb collisions ΔφΔφ Phys. Rev. C 84, (2011 ) D. KrofcheckDijet Probes of Hot Nuclear Matter at the LHC33

Jet production in PbPb collisions D. KrofcheckDijet Probes of Hot Nuclear Matter at the LHC34 gamma-jet correlation in QCD “medium” Gamma Nuclear remnant

Momentum ratio shifts/decreases with centrality –jets shifting below the 30 GeV p T threshold not included Submitted to PLB, arXiv: Observed momentum imbalance in γ – jet correlation D. KrofcheckDijet Probes of Hot Nuclear Matter at the LHC35

Energy Units! 1 eV= 1 electron Volt Energy to ionise hydrogen = 13.6 eV 1 keV(kilo)=1,000 eV= 10 3 eV Medical X-ray ~ 200 keV 1 MeV(Mega)=1,000,000 eV= 10 6 eV Alpha particle decay of uranium 4.2 MeV 1 GeV(Giga)=1,000,000,000 eV= 10 9 eV LEP collider beam ( ) = 45 GeV 1 TeV(Tera)=1,000,000,000,000 eV= eV Highest energy accelerator in world = 1 TeV (Tevatron) Electron Volt – Energy gained by an electron when accelerated in an electric field through a potential difference of 1 volt. Highest energies found in cosmic rays (>10 20 eV)

Interactions between matter particles

Why are there so many different substances in the world? D. KrofcheckCanterbury Teachers Workshop40