Related papers: Light Scalar Mesons in Photon-Photon Collisions
The following topics are considered. 1) Confinement, chiral dynamics, and light scalar mesons. 2) Chiral shielding of the \sigma(600) 3)The \phi meson radiative decays about nature of light scalar resonances. 4) The J/\psi decays about…
High intensity back-scattered laser beams will allow the efficient conversion of a substantial fraction of the incident lepton energy into high energy photons, thus significantly extending the physics capabilities of an electron-electron or…
The elastic scattering of two real photons in vacuum is one of the most elusive of the fundamentally new processes predicted by quantum electrodynamics. This explains why, although it was first predicted more than eighty years ago, it has…
A search is presented for the pair production of light scalar top quarks in sqrt(s) = 7 TeV proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider. This analysis uses the full data sample collected during…
The production of mesons in ultra-peripheral collisions of relativistic heavy ions is re-analyzed using a projection technique to calculate the amplitudes for the appropriate Feynman diagrams. The virtuality of the exchanged photons is…
Light scalar mesons are found to fit rather well a diquark-antidiquark description. The resulting nonet obeys mass formulae which respect, to a good extent, the OZI rule. OZI allowed strong decays are reasonably reproduced by a single…
The ${q}\bar{q}$ spectrum is studied within a chiral constituent quark model. It provides with a good fit of the available experimental data from light (vector and pseudoscalar) to heavy mesons. The new $D$ states measured at different…
Taking into account the exchange forces between protons of scalar, pseudoscalar, vector and axial vector type the cross sections of neutral and charged scalar mesons $a_0(980)$, $a_+(980)$, $f_0(980)$, $\sigma(600)$ production are…
The scalar mesons f0(1370), f0(1500) and f0(1710) are of interest as there is as yet no consensus of their status, or indeed of the existence of the f0(1370). Radiative decays to rho and omega have been shown to provide effective probes of…
Heavy ion collisions at RHIC and at the LHC can create the quark-gluon plasma, a state of matter at very high temperatures. Among a plethora of particles that are produced in these collisions, also light is emitted throughout the evolution…
The quark structure of the $f_2(1270)$ meson has, for many years, been assumed to be a pure quark-antiquark ($q\bar{q}$) resonance with quantum numbers $J^{PC} = 2^{++}$. Recently, it was proposed that the $f_2(1270)$ is a molecular state…
Many measurements of pseudoscalar mesons with S = 0 photoproduced on the proton have been made recently. These new data are particularly useful in theoretical investigations of nucleon resonances. How the new data from various labs…
In this paper, we present results on strong two-body decay widths of light $q\bar q$ mesons calculated in a covariant quark model. The model is based on the Bethe-Salpeter equation in its instantaneous approximation and has already been…
We study the cosmological evolution and phenomenological properties of scalar bosons in the keV to MeV range that have a tiny mixing with the Standard Model Higgs boson. The mixing determines both the abundance of light scalars produced via…
The axion is just one from a general class of new particles -- called Light Pseudoscalar Bosons (LPBs) -- predicted by many realistic extensions of the Standard Model. We offer a somewhat pedagogical review of their main properties, with…
The corrections to the current algebra mass formulae for the pseudoscalar mesons are analyzed by means of a simultaneous exansion in powers of the light quark masses and powers of 1/N. A set of mass formulae is derived, including an…
LEP offers an excellent opportunity to measure two photon processes over a large kinematical range and thus study the complex nature of the photon. This article reviews the experimental status of ``Two Photon Physics'' at LEP. The recent…
The origin of the lightest scalar mesons is studied in the framework of instanton liquid model (ILM) of the QCD vacuum. The impact of vacuum excitations on the sigma-meson features is analyzed in detail. In particular, it is noticed that…
After years of experimental and theoretical efforts, direct photons become a strong and reliable tool to establish the basic characteristics of a hot and dense matter produced in heavy ion collisions. The recent direct photon measurements…
In the framework of the constituent quark model the exclusive pair production of the charmed mesons in the photon-photon interaction is calculated. The comparison of these predictions with the ones of the heavy quark effective theory is…