Related papers: gamma* gamma -> pi pi at large Q^2
The cosmological QCD phase transition is studied in terms of the color confinement at finite temperature using the dual Higgs theory of QCD. The confinement force is largely reduced at high temperature, which leads to the swelling of…
We study the process $\gamma\gamma\to\pi^0\pi^0$ involving the principle mechanisms, the structure of its cross section and the role of individual isoscalar-tensor resonances in the saturation of its energy spectrum.
We give an analytic formula for the double distribution of hadronic invariant mass and charged lepton energy to one-loop order of the perturbative QCD. Although infrared singular, this quantity is closely related to physical observables…
We will report on the status of a new large scale calculation of thermodynamic quantities in QCD with light up and down quarks corresponding to an almost physical light quark mass value and a heavier strange quark mass. These calculations…
We discuss the nature of phase transitions in self-gravitating systems both in the microcanonical and in the canonical ensemble. We avoid the divergence of the gravitational potential at short distances by considering the case of…
We review the potentialities offered by the study of backward exclusive processes in a new scaling regime, i.e. involving a large -timelike or spacelike- Q2 photon and a baryonic exchange in the t-channel. We recall the concept of…
We report a new measurement of the exclusive electroproduction reaction gamma* p -> pi0 p to explore the evolution from soft non-perturbative physics to hard processes via the Q2 dependence of the magnetic (M1+), electric (E1+) and scalar…
The chiral phase transition of the quark sector of QCD is investigated within the Hamiltonian approach in Coulomb gauge. Finite temperatures $T$ are introduced by compactifying one spatial dimension, which makes all thermodynamical…
We analyse the exclusive channel $p\pb\to\gamma \pi^0$, assuming handbag dominance. The soft parts are parametrized in terms of CGLN amplitudes for the $q\qb\to\gamma \pi^0$ transition and form factors for the $p\pb\to q\qb$ ones, the…
We obtain the hadronic mass spectrum in the `bag of bags' statistical bootstrap model (BBSBM), implementing the colorless state condition, aside of baryon and strangeness conservation, using group projection method. We study the partition…
The method of light-cone QCD sum rules is applied to the calculation of the form factors of $\gamma^*\rho \to \pi$ and $\gamma^*\gamma \to \pi^0$ transitions. We consider the dispersion relation for the $\gamma^*(Q^2)\gamma^*(q^2) \to…
Power-suppressed corrections coming from the end-point integration regions in the amplitude of the process $\gamma^{*}\gamma \to \pi \pi$ at large $Q^2$ and small squared center-of-mass energy $W^2$ are calculated in the QCD hard-scattering…
In recent years, significant progress was reached in understanding of vacuum and hadronic structure. We review recent works on the {\it point-to-point correlation functions}, comparing those obtained from phenomenology, ``instanton liquid"…
A novel attempt has been made to probe the QCD phase boundary by using the experimental data for transverse momenta of {\phi} mesons produced in nuclear collisions at AGS, SPS and RHIC energies. The data are confronted with simple…
We reanalyse the gamma-gamma scattering data and conclude that in the mass region below 1 GeV the cross section for gamma-gamma to pi^0-pi^0 can be largely explained by the one pion exchange process with pi-pi rescattering. The radiative…
Quark-hadron duality implies that a process described in terms of quark loops should be the hadronic amplitude when averaged over a sufficient number of states. Ambiguities associated with the notion of quark hadron duality can be made…
We present a determination of the $P$-wave $\pi\pi\to\pi\gamma^\star$ transition amplitude from lattice quantum chromodynamics. Matrix elements of the vector current in a finite-volume are extracted from three-point correlation functions,…
We propose a formalism to extract the $\gamma\pi\to\pi\pi$ chiral anomaly $F_{3\pi}$ from calculations in lattice QCD performed at larger-than-physical pion masses. To this end, we start from a dispersive representation of the…
The QCD transition from a hadronic to a quark-gluon plasma phase is a cross-over at vanishing/small baryo-chemical potential, while at higher chemical potentials it is argued that it becomes of first order, ending with a critical end-point.…
We study the possibility of detecting noncommutative QED through neutral Higgs boson pair production at (gamma--gamma) collider. This is based on the assumption that H^0 interacts directly with photon as suggested by symmetry…