What’s Hot in High Energy Particle Physics Study of the fundamental constituents & interactions of matter. What is the universe made of and by what rules do they play?

Masses on the subatomic scale electron proton iron nucleus  kg MeV  kg MeV  kg MeV

Henri Becquerel ( ) 1903 Nobel Prize discovery of natural radioactivity Wrapped photographic plate showed distinct silhouettes of uranium salt samples stored atop it While studying fluorescent & phosphorescent materials, Becquerel finds potassium-uranyl sulfate spontaneously emits radiation that can penetrate  thick opaque black paper  aluminum plates  copper plates

fast charged particles leave a trails of Ag grains 1/1000 mm (1/25000 in) diameter 1930s plates coated with thick photographic emulsions (gelatins carrying silver bromide crystals) carried up mountains or in balloons clearly trace cosmic ray tracks through their depth when developed

C.F.Powell, P.H. Fowler, D.H.Perkins Nature 159, 694 (1947) Nature 163, 82 (1949)

e   Particle Data Group Created: 10/24/2002

Particle Data Group Created: 06/18/2002     0  150 mesons!!

p n Particle Data Group Created: 06/18/2002

121 baryons!!

c s du p n + + + + 0 0 Quark Charge up +2/3 e down  1/3 e charm +2/3 e strange  1/3 e

Baryon States State Quark content Mass Spin p uud MeV 1/2 n udd MeV 1/2  uds MeV 1/2  + uus MeV 1/2  0 uds MeV 1/2  - dds MeV 1/2  0 uss MeV 1/2   dss MeV 1/2   uuu MeV 3/2    uud 1231 MeV 3/2  0 udd 1233 MeV 3/2  - ddd 1234 MeV 3/2  * + uus MeV 3/2  * 0 uds MeV 3/2  *  dds MeV 3/2  * 0 uss MeV 3/2  *  dss MeV 3/2   sss MeV 3/2 can all be explained as combinations of 3 fundamental quarks Meson States can all be explained 2 quarks combinations  + ud MeV  0 uu MeV  0 dd MeV

To be charged : means the particle is capable of emitting and absorbing photons e  e  How do 2 (mutually repulsive) electrons sense one another’s presence?

 e e   W     ee ee ee ee electrostatic repulsion nuclear binding u u d d g “weak” decays

The Detector in various stages of assembly

38 foreign institutions 3 national labs:BNL, LBL,FNAL 36 U.S. university HEP groups

CERN, Geneva, Switzerland The CMS Detector

The Cosmic Questions Why are there so many particles? Are there yet any new laws to discover? What is this Dark Matter? What are massive neutrinos telling us about the world? Are there dimensions beyond 4-dimensional space-time? Do the fundamental forces unify? How did the universe come to be? Where did all the antimatter go? What is the origin of particle masses?

Astronomers say that most of the matter in the Universe is invisible Dark Matter Supersymmetric particles ? Something we are actively looking for!

ee pp ee pp m proton = 1836  m electron

~ ~ ~ ~ ~ Particle Name Symbol Spartner Name Symbol gluon g gluino g charged Higgs H + chargino W 1,2 charged weak boson light Higgs h neutralino Z 1,2,3,4 heavy Higgs H pseudoscalar Higgs A neutral weak boson Z photon  quark q squark q R,L lepton l slepton l R,L SUPERSYMMETRY

Charginos and Neutralinos Production of   1  0 2 will lead to trilepton final states with E T perhaps the cleanest signature of supersymmetry. pp  q, g    1  0 2  + E T ~ ~ 1 021 02 ~ ~ 0101 ~ 0101 ~ W* Z* W* qqqq qqqq 102102 ~ ~ 11 ~ 0202 ~  ~ 0101 ~   *  ~  0101 ~ ~ q* ~

qq gg  01 01 q  01 01 q q Squarks and Gluinos Squarks and Gluinos can decay directly into the LSP (  0 1 ) or cascade down to the LSP  qq gg q So that the dominant signature for pp  qq, qg, gg + X is jets+E T    q q q qq 0202 qq  01 01 qq  g g qq q q q  1 1 q q  01 01 qq

Supersymmetry Searches at LHC `Typical’ supersymmetric Event at the LHC LHC reach in supersymmetric parameter space Can cover most possibilities for astrophysical dark matter

String Theory Candidate theory of quantum gravity Point-like particles → extended objects lengths of “string” Requires extra dimensions

R  Flat dimension 

Picking a fundamental particle for common reference for r >> R If photons traverse our 3-dim spacebut gravitons spread out over 3+n…

So far NO distribution of measured particle characteristics or behavior show ANY effect attributable to extra dimensions.

Hints on the Higgs Mass Best-fit value: m H = 91+45–32 GeV 95% confidence-level upper limit: m H < 219 GeV

Best-fit value: m H = 91+45–32 GeV 95% confidence-level upper limit: m H < 219 GeV current limit fixed by direct searches m H > 114 GeV I’s expected reach (before CERN’s LHC turns on) ~120 GeV