QCD Studies Sergio Bertolucci February 1 2006 QCD

QCD Studies Sergio Bertolucci February 1, 2006

QCD Studies Ø Detailed understanding of QCD is a necessity to do the best physics at LHC/ILC colliders, CP physics, neutrinoless double beta decays, astrophysics. . Ø There is a continuum between particle physics and “nuclear physics”

QCD Studies Ø What is the proton structure? Ø What is the photon structure? Ø How precisely can we understand many-jet final states and heavy flavour production at colliders? Ø How well do we understand nuclear matrix elements and hadronic wave functions? Ø How well we understand low x, saturation, modification of the evolution functions? Ø Is there a new state of matter (Colour Glass Condensate)? Ø Do we understand the nature of new observed states? Ø. . .

New and old spectroscopies New Puzzles: Belle, Ba. Bar, (CDF and D 0) agree on the existence of new narrow objects: X(3872), Y(4260), X(3940), whose interpretation as charmonium states has been excluded! What are these objects? Molecules, hybrids, multiquark states? Old puzzles: The scalar composite sub-Ge. V mesons (new studies underway at Ba. Bar and Dafne )

QCD studies at low energies Precision measurements of shad for e+e- below the J/Y needed to perform precision measurements at the ILC shad between 1 and 2 Ge. V is the next important contribution to gm - 2.

QCD studies: GPD Exclusive channels (deeply virtual Compton scattering, vector meson production Begin to really build up a 3 D map of the partons in the proton - “parton tomography”. COMPASS (intermediate x) H 1, ZEUS and HERMES, FP 420 and FAIR (polarized antiprotons)

Heavy Ions and QGP Nuclear Physics Perturbative QCD Non-perturbative QCD Voodoo QCD (BJ definition) Statistical Mech. Hydrodynamics Small x physics

Heavy Ions and QGP

Heavy ions at the LHC A new regime: 1. Lifetime of the quark-gluon plasma: The expected particle density at LHC is a factor of 2 higher then RHIC, which leads to qualitative changes: relativistic hydrodynamics alone should do a good job in describing all soft hadronic (fireball) observables. Furthermore, ALICE does better than any heavy-ion experiment ever in the soft region (particle identification at low pt) 2. High-pt physics: Jet reconstruction at LHC will allow to study the quenching mechanism in detail

Heavy ions at the SPS Temperatures in Pb-Pb collisions at SPS are just below the critical point of QCD, predicted by lattice. Collisions of smaller nuclei yield somewhat higher temperatures, coming closer to the critical point. Large fluctuations are expected near a critical point. This study, with an improved detector, is one of the goals of the future-NA 49 experiment.

In summary (QCD) Continued need of detailed QCD studies to keep the pace of higher precision measurements. Need to preserve/transmit all the information collected at Hera and the Tevatron Low energy measurements of higher quality needed

In summary (Heavy Ions) An exciting era is opening up with Alice. Valuable informations are still coming from the SPS A planning of the LHC operation is very much needed to minimize interference with the high luminosity program. A reflection on the long term future of the field has started and should be encouraged.