Related papers: Have Gluonic Excitations Been Found?
Hybrid mesons consist of a quark-antiquark pair bound together by a gluonic field that is in an excited state. Measuring the spectrum of these states will provide valuable information on the gluonic degrees of freedom of QCD in the…
Using the ZEUS detector at HERA, we have searched for heavy excited states of electrons, neutrinos, and quarks in $e^+p$ collisions at a center-of-mass energy of 300~GeV. With an integrated luminosity of 9.4~pb$^{-1}$, no evidence was found…
We report on the measurement of the two-dimensional differential cross section for near-threshold J/$\psi \to \mu^+\mu^-$ photoproduction from the J/$\psi$-007 experiment in Hall C at Jefferson Lab. Our results agree with the previously…
An understanding of the confinement mechanism in QCD requires a detailed mapping of the spectrum of hybrid mesons. Understanding confinement means understanding the role of gluons and it is in hybrid mesons that the gluonic degrees of…
We show how exclusive vector meson production off light ions can be used to probe the spatial distribution of small-$x$ gluons in the deuteron and $^3$He wave functions. In particular, we demonstrate how short range repulsive…
We apply the QCD sum rule method to study the double-gluon hybrid states with the quark-gluon contents $\bar q q gg$ ($q=u/d$) and $\bar s s gg$. We construct twenty-eight double-gluon hybrid currents, eleven of which are found to be zero…
Hadrons with explicit gluonic degrees of freedom, such as charmonium hybrids, are key to understanding nonperturbative behavior of strong interaction, yet they remain experimentally elusive. Within a constituent gluon model treating the…
A search is performed for the pair production of spin-3/2 excited top quarks, each decaying to a top quark and a gluon. The search uses the data collected with the CMS detector from proton-proton collisions at a center-of-mass energy of 13…
We discuss in general the construction of gauge-invariant non-local meson operators on the lattice. We use such operators to study the $P$- and $D$-wave mesons as well as hybrid mesons in quenched QCD, with quark masses near the strange…
We revisit the masses of heavy quarkonium double-gluon hybrid mesons with exotic quantum numbers $J^{PC}=1^{-+}$ and $2^{+-}$ in the framework of the QCD sum rules. Considering the double-gluon hybrid meson operators in the octet-octet…
Using SU(3) lattice QCD, we perform the first systematic study for the ground-state three-quark (3Q) potential $V_{\rm 3Q}^{\rm g.s.}$ and the 1st excited-state 3Q potential $V_{\rm 3Q}^{\rm e.s.}$, {\it i.e.}, the energies of the ground…
We explore the spectrum of excited and exotic bottomonia using lattice QCD. Highly excited states are identified with masses up to 11,000 MeV, many of which can be grouped into supermultiplets matching those of the quark model while exotic…
We estimate the kinematic dependence of the exclusive photo-- and electroproduction of $J^{PC}=1^{-+}$ exotic mesons due to $\pi$ exchange. We show that the kinematic dependence is largely independent of the exotic meson form factor, which…
This is the first study on the double-gluon hybrid, which consists of one valence quark and one valence antiquark together with two valence gluons. We concentrate on the one with the exotic quantum number $J^{PC} = 2^{+-}$ that conventional…
One of the most important tasks in high energy physics is search for the exotic states, such as glueball, hybrid and multi-quark states. The transitions $\psi(ns)\to \psi(ms)+\pi\pi$ and $\Upsilon(ns)\to \Upsilon(ms)+\pi\pi$ attract great…
Non-perturbative QCD mechanisms are of fundamental importance in strong interaction physics. In particular, the flavor singlet axial anomaly leads to a gluonic pole mechanism which has been shown to explain the $\eta^{\prime}$ mass,…
The firm understanding of standard quark-antiquark states (including excited states) is necessary to search for non-conventional mesons with the same quantum numbers. In this work, we study the phenomenology of two nonets of excited vector…
We have searched for unstable neutral and charged heavy leptons, N and L^+/-, and for excited states of neutral and charged leptons, nu*, e*, mu* and tau*, in e^+e^- collisions at centre-of-mass energies of 170 and 172 GeV using the OPAL…
We demonstrate that the cubic antifluorite-type halides K$_2$OsCl$_6$, K$_2$OsBr$_6$, and Rb$_2$OsBr$_6$ are excellent realizations of non-magnetic J=0 compounds. The magnetic susceptibility shows the corresponding Van-Vleck type behavior…
This document outlines major directions in theoretical support for the measurement of nucleon resonance transition form factors at the JLab 12 GeV upgrade with the CLAS12 detector. Using single and double meson production, prominent…