what’s hot in high energy particle physics

What’s Hot inHigh 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

9.109310-31 kg 0.511 MeV

1.672110-27 kg 938.28 MeV

9.299010-26 kg 52153.77 MeV

Henri Becquerel (1852-1908) 1903 Nobel Prize

discovery of natural radioactivity

Wrapped photographic plate showed distinct silhouettes of uranium salt samples stored atop it.

1896 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.PerkinsNature 159, 694 (1947)

Nature 163, 82 (1949)

ee

e

HTTP://PDG.LBL.GOV Particle Data Group Created: 10/24/2002

HTTP://PDG.LBL.GOV Particle Data Group Created: 06/18/2002

0

150 mesons!!

p

n

HTTP://PDG.LBL.GOV Particle Data Group Created: 06/18/2002

121 baryons!!

c

sd u

p n + + 0

Quark Charge up +2/3e down 1/3e charm +2/3estrange 1/3e

Baryon StatesState Quark content Mass Spin p uud 938.272 MeV 1/2 n udd 939.565 MeV 1/2 uds 1115.683 MeV 1/2 + uus 1189.37 MeV 1/2 0 uds 1192.632 MeV 1/2 - dds 1197.449 MeV 1/2 0 uss 1314.9 MeV 1/2 dss 1321.32 MeV 1/2

uuu 1230. MeV 3/2 uud 1231 MeV 3/2 0 udd 1233 MeV 3/2 - ddd 1234 MeV 3/2 *+ uus 1382.8 MeV 3/2 *0 uds 1383.7 MeV 3/2 * dds 1387.2 MeV 3/2 *0 uss 1531.80 MeV 3/2 * dss 1535.0 MeV 3/2 sss 1672.45 MeV 3/2

can all be explained as combinations of

3 fundamental quarks

Meson Statescan all be explained

2 quarks combinations

+ ud 139.57 MeV + ud 139.57 MeV 0 uu 134.98 MeV 0 dd 546.30 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

electrostatic repulsion

nuclear binding

u

u

d

d

g

“weak” decays

The Detector in various stages of assembly

38 foreign institutions3 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 tell us that most of the matter in the universe is invisible

We will look for it

with the LHC

Dark Matter in the Universe

Astronomers saythat most of thematter in theUniverse isinvisible Dark Matter

Supersymmetric particles ?

Something we are actively looking for!

e

p

e

p

mproton = 1836 melectron

~

~

~~

~Particle Name Symbol Spartner Name Symbol gluon g gluino g charged Higgs H+ chargino W1,2

charged weak boson light Higgs h neutralino Z1,2,3,4 heavy Higgs Hpseudoscalar Higgs Aneutral weak boson Z photon quark q squark qR,L

lepton l slepton lR,L

SUPERSYMMETRY

Charginos and NeutralinosCharginos and Neutralinos

Production of 1 0

2 will lead to trilepton final states with ET

perhaps the cleanest signature of supersymmetry.

pp q, g 10

2

+ ET

~ ~ ~ ~

1

02

~

~

01

~

01

~

W*Z*

W*

q

q

q

q

1

02

~

~

1

~ 02

~

~0

1~

*

~

01

~

~ ~

q*~

q

g

0

1q

0

1

q

q

Squarks and GluinosSquarks and Gluinos can decay directly into the LSP

(01)

or cascade down to the LSP

q

g

q

So that the dominant signature for ppqq, qg, gg + X is jets+ET

q

q

q

q

0

2

q

0

1

q

g q

qq

q

1

q

q

0

1

q

Supersymmetry Searches at LHC

`Typical’ supersymmetric

Event at the LHC

LHC reach in

supersymmetric

parameter space

Can cover mostpossibilities forastrophysicaldark matter

String Theory• Candidate theory of quantum

gravity• Point-like particles →

extended objects• lengths of “string”• Requires extra dimensions

R

Flat dimension

221

r

mmGF

gravity 2

21

r

qqkF

ticelectrosta

Picking a fundamental particle for common reference

kgmproton

271067265.1 Cqproton

19106022.1

ticelectrostagravityFF

00000000000000000000000000000001000000000

1

rR

mm

MrR

mm

MrV n

Planck

nn

Dgravity

212

212

11)( for r >> R

If photons traverse our 3-dim space but 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: mH = 91+45–32 GeV95% confidence-level upper limit: mH < 219 GeV

Best-fit value: mH = 91+45–32 GeV

95% confidence-level upper limit: mH < 219 GeV

current limit fixed by direct searchesmH > 114 GeV

I’s expected reach (before CERN’s LHC turns on)

~120 GeV