Novel QCD Phenomenology

I review a number of topics where conventional wisdom in hadron physics has been challenged. For example, hadrons can be produced at large transverse momentum directly within a hard higher-twist QCD subprocess, rather than from jet fragmentation. Such "direct" processes can explain the deviations from perturbative QCD predictions in measurements of inclusive hadron cross sections at fixed x_T= 2p_T/\sqrt s, as well as the "baryon anomaly", the anomalously large proton-to-pion ratio seen in high centrality heavy ion collisions. Initial-state and final-state interactions of the struck quark lead to Bjorken-scaling single-spin asymmetries, diffractive deep inelastic scattering, the breakdown of the Lam-Tung relation in Drell-Yan reactions, as well as nuclear shadowing and antishadowing. The Gribov-Glauber theory predicts that antishadowing of nuclear structure functions is not universal, but instead depends on the flavor quantum numbers of each quark and antiquark, thus explaining the anomalous nuclear dependence measured in deep-inelastic neutrino scattering. One cannot attribute such phenomena to the structure of the hadron or nucleus itself. It is thus important to distinguish "static" structure functions computed from the square of the target light-front wavefunctions, versus "dynamical" structure functions which include the effects of the final-state rescattering of the struck quark. The importance of the J=0 photon-quark QCD contact interaction in deeply virtual Compton scattering is emphasized. The scheme-independent BLM method for setting the renormalization scale is discussed. Eliminating the renormalization scale ambiguity greatly improves the precision of QCD predictions and increases the sensitivity of searches for new physics at the LHC. Other novel features of QCD are discussed, including the consequences of confinement for quark and gluon condensates.Comment: Invited talk, presented at the Gribov-80 Memorial Workshop on Quantum Chromodynamics and Beyond, May, 2010, Abdus Salam International Centre for Theoretical Physics. Trieste, Ital

Phenomenology from lattice QCD

After a short presentation of lattice QCD and some of its current practical limitations, I review recent progress in applications to phenomenology. Emphasis is placed on heavy-quark masses and on hadronic weak matrix elements relevant for constraining the CKM unitarity triangle. The main numerical results are highlighted in boxes.Comment: 18 pages, 14 postscript figures. Plenary talk at ICHEP 2002, 24-31 July 2002, Amsterdam, The Netherland

Instantons and the Large N_c Limit of QCD

We summarize our current understanding of instantons in the large N_c limit of QCD. We also present some recent results from simulations of the instanton liquid in QCD for N_c>3.Comment: 10 pages; talk given at the Workshop on the Phenomenology of Large N_C QCD, ASU (Jan. 2002), to be published in the proceeding

QCD Working Group Report

This is the report of the QCD working group at WHEPP 6. Discussions and work on heavy ion collisions, polarised scattering, and collider phenomenology are reported.Comment: Report of the QCD group at WHEPP-6, Chennai, January 2000. 7 page

Compatibility of a model for the QCD-Pomeron and chiral-symmetry breaking phenomenologies

The phenomenology of a QCD-Pomeron model based on the exchange of a pair of non-perturbative gluons, i.e. gluon fields with a finite correlation length in the vacuum, is studied in comparison with the phenomenology of QCD chiral symmetry breaking, based on non-perturbative solutions of Schwinger-Dyson equations for the quark propagator including these non-perturbative gluon effects. We show that these models are incompatible, and point out some possibles origins of this problem.Comment: 21 pages, uuencoded latex file, 3 postscript figures, uses epsf.sty and epsf.tex. To be published in Phys. Lett.

QCD Phenomenology of Static Sources

We discuss the spectrum of open string and point particle excitations in QCD with various source representations. Some general relations are introduced and lattice results presented. In particular we discuss the short-distance behaviour, relate this to perturbation theory expectations and comment on the matching between low energy matrix elements and high energy Wilson coefficients, within the framework of effective field theories.Comment: Invited Talk presented at LightCone 2004, 16-20 August 2004, Amsterdam, 10 page

Recent BCP progress in Taiwan

I review theoretical progresses on $B$ physics and CP violation which were made in Taiwan recently. I concentrate on the approaches to exclusive $B$ meson decays based on factorization assumption, SU(3) symmetry, perturbative QCD factorization theorem, QCD factorization, and light-front QCD formalism.Comment: 8 pages, talk presented at the 5th International Workshop on Particle Physics Phenomenology, Chi-Pen, Taitung, Taiwan, Nov. 8-11, 200