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Big questions why are quarks confined inside protons ?

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.

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Big questions why are quarks confined inside protons ?

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  1. 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 cogilvie@iastate.edu

  2. t z Quantum Chromodynamics (QCD) quark quark quark quark Strong interaction/scattering by exchange of gluons Force between two quarks does not weaken as you separate them Completely counter-intuitive Gravity, electric, magnetic forces all are weaker at larger distances cogilvie@iastate.edu

  3. Confinement: A Partial Answer • Attractive interaction • try to separate quarks, force pulls them back • More complicated …… try to separate quarks narrow “string” or color field / gluons cogilvie@iastate.edu

  4. q q vacuum expels QCD field (gluons), Restricts gluons to be between quarks in “string” q q • Confinement • Attractive force as you try to separate quarks • vacuum expels color field • quarks must stay “outside the vacuum” i.e. inside hadrons! Confinement: The rest of the story “vacuum” is not empty!!, short-lived creation/destruction of particle pairs cogilvie@iastate.edu

  5. 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 plasma • Melts the vacuum • Detailed study of the quarks, gluons inside a proton • Spin of a proton • Low-momentum region <= high density of gluons cogilvie@iastate.edu

  6. 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 cogilvie@iastate.edu

  7. BRAHMS PHOBOS PHENIX STAR Long Island RHIC • Two independent accelerator rings • 3.83 km in circumference • Accelerates everything, from p to Au Ös p-p 500 GeV Au-Au 200 GeV cogilvie@iastate.edu

  8. STAR Au on Au Event at CM Energy 130 GeV*A cogilvie@iastate.edu

  9. PHENIX at RHIC • 2 central spectrometers West • 2 forward spectrometers South East North cogilvie@iastate.edu

  10. Silicon Detector Upgrade to PHENIX Two layers of silicon pixel detectors Two layers of silicon strip detectors Tracks extropolate back to collision vertex Displaced vertices => charm (D), beauty (B) Requires ~ 50 mm precision e X De+X Au Au B e+X e X e p0 e+e- cogilvie@iastate.edu

  11. Nuclear Physics @ ISU • Many-body QCD • Experiment and theory • Densest, hottest matter: QGP, RHIC and LHC • Detailed study of the quarks, gluons inside a proton • Strongest gluon field possible in protons+nuclei • Large, active, enthusiastic group • Well-funded • Hardware experience • Exciting physics • Open invitation to join our group cogilvie@iastate.edu

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