No Arabic abstract
We classify the meson and baryon long lived resonances considering quarks with electric charge 5/3 and $-4/3$ (in units of $vert evert$) predicted by some 3-3-1 models. Some of these exotic resonances have the usual electric charges $0,pm1$, others have $pm(3,4,5)$, and the lightest ones decaying only into leptons plus known resonances. We propose another heavy $SU(3)_H$ global symmetry under which hadrons involving only exotic quarks can be constructed.
Many new states in the charmonium and bottomonium mass region were recently discovered by the BaBar, Belle and CDF Collaborations. We use the QCD Sum Rule approach to study the possible structure of some of these states. In particular we identify the recently observed bottomonium-like resonance $Z_b^+(10610)$ with the first excitation of the tetraquark $X_b(1^{++})$, the analogue of the X(3872) state in the charm sector.
We reconsider the question of electric charge quantization, which leads to the existence of a dark charge nontrivially unified with weak isospin in a novel gauge symmetry, $SU(3)_Cotimes SU(2)_Lotimes U(1)_Yotimes U(1)_N$, where $Y$ and $N$ determine the electric and dark charges, respectively. The new model provides neutrino masses and dark matter appropriately, a direct consequence of the dark dynamics. We diagonalize the fermion, scalar, and gauge sectors as well as obtain relevant interactions, taking into account the kinetic mixing of $U(1)_{Y,N}$ gauge bosons. The new physics signals at colliders are examined. The dark matter observables are discussed.
We report on a measurement of the top-quark electric charge in ttbar events in which one W boson originating from the top-quark pair decays into leptons and the other into hadrons. The event sample was collected by the CDF II detector in sqrt(s)=1.96 TeV proton-antiproton collisions and corresponds to 5.6 fb^(-1). We find the data to be consistent with the standard model and exclude the existence of an exotic quark with -4/3 electric charge and mass of the conventional top quark at the 99% confidence level.
In this paper we investigate the Exotic Charmonium (EC) production in $gamma gamma$ interactions present in proton-proton, proton-nucleus and nucleus-nucleus collisions at the CERN Large Hadron Collider (LHC) energies as well as for the proposed energies of the Future Circular Collider (FCC). Our results demonstrate that the experimental study of these processes is feasible and can be used to constrain the theoretical decay widths and shed some light on the configuration of the considered multiquark states.
The tree-level partonic angular distribution of Standard Model $Wgamma$ production possesses a feature known as the Radiation Amplitude Zero (RAZ) where destructive interference causes the cross section to vanish. At the proton level the exact cancellation disappears, however, one can find a dip in the central region of the angular distributions, here called the Radiation Valley (RV). In this paper, we show how the sensitivity for $W(ell u)gamma$ resonances can be significantly improved if one focuses on events in the RV region. Using this technique, we find that the LHC could probe a larger range of resonance masses, equivalent to increasing the luminosity by a factor of $2-3$ over conventional searches. The exact increase depends on the spin of the $Wgamma$ resonance and exactly how it couples to electroweak gauge bosons.