what’s hot in high energy particle physics
DESCRIPTION
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. 9.1093 10 -31 kg. 0.511 MeV. 938.28 MeV. - PowerPoint PPT PresentationTRANSCRIPT
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
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
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