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Big questions why are quarks confined inside protons ?
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[email protected] 1 Big questions why are quarks confined inside protons ? artist’s view :) what does the vacuum look like ? can we use understanding of 2-body physics to describe complex behavior of n-body physics ear Physics/Quantum Chromodynamics (QCD 11/03/2009
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Big questions why are quarks confined inside protons ?. artist’s view :). Nuclear Physics/Quantum Chromodynamics (QCD). what does the vacuum look like ? can we use understanding of 2-body physics to describe complex behavior of n-body physics. t. z. Quantum Chromodynamics (QCD). quark. - PowerPoint PPT Presentation
Transcript of Big questions why are quarks confined inside protons ?
Big questions why are quarks confined inside protons ?
artist’s view :)
what does the vacuum look like ?
can we use understanding of 2-body physics to describe complex behavior of n-body physics
Nuclear Physics/Quantum Chromodynamics (QCD)
11/03/2009
Quantum Chromodynamics (QCD)
Strong interaction/scattering by exchange of gluons
quark
quark
quark
quarkt
z
Force between two quarks does not weaken as you separate them
Completely counter-intuitive
Gravity, electric, magnetic forces all are weaker at larger distances
11/03/2009
Confinement: A Partial Answer
Attractive interaction try to separate quarks, force pulls them back
More complicated ……
narrow “string” orcolor field / gluons
try to separate quarks
11/03/2009
Confinement: The rest of the story
“vacuum” is not empty!!,
short-lived creation/destruction of particle pairs
q
q
vacuum expels QCD field (gluons),
Restricts gluons to be between quarks in “string”
Confinement1) Attractive force as you try to separate quarks2) vacuum expels color field quarks must stay “outside the vacuum” i.e. inside hadrons!
11/03/2009
Attack QCD on Multiple Fronts: ISU Program
Experiments that push our understanding of strong QCD Form + study a bulk system of very hot quarks and gluons
Quark-gluon plasmaMelts the vacuum
Detailed study of the quarks, gluons inside a proton Spin of a proton Low-momentum region <= high density of gluons
11/03/2009
The Quark-Gluon Plasma
In all protons, neutrons, the quarks are confined to radius ~ 1x10-15m
Inside a nucleus, average separation between nucleons is ~ 2x10-15m
Increase density by compression or heating nucleons significantly overlap quarks, gluons no longer confined, QGP : new form of hot, dense matter
11/03/2009
11/03/2009 [email protected] 7
RHIC
Two independent accelerator rings
3.83 km in circumference
Accelerates everything,
from p to Au
s
p-p 500 GeV
Au-Au 200 GeV
BRAHMSPHOBO
S
PHENIX
Long Island
Long Island
STAR
PHENIX at RHIC
2 central spectrometers
2 forward spectrometers
West
EastSouth
North
11/03/2009
11/03/2009 [email protected] 10
Silicon Detector Upgrade to PHENIX
Two layers of silicon pixel detectorsTwo layers of silicon strip detectors
Tracks extropolate back to collision vertexDisplaced vertices => charm (D), beauty (B)
Requires ~ 50 m precision
De+X Au
e
Au
X
B e+X
Xee ee
11/03/2009 [email protected] 11
Nuclear Physics @ ISU
Many-body QCD Experiment and theory
Densest, hottest matter: QGP, RHIC and LHCDetailed study of the quarks, gluons inside a protonStrongest gluon field possible in protons+nuclei
Large, active, enthusiastic group Well-funded Hardware experience Exciting physics
Open invitation to join our group
