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New resonances with masses of order a few ${rm TeV}$ might be discovered at the LHC. We show that no resonance that couples to electrons only through Standard Model interactions can decay to both $e^+e^-$and $gamma gamma$ with significant branching ratios. This means that finding both electron-positron and two-photon final states is evidence that electrons couple directly to the new physics associated with the resonance and furthermore that the resonance is not spin-1. The least fine-tuned such examples involve electron compositeness. One such example, Kaluza Klein excitations of the graviton in the version of the Randall Sundrum Model where Standard Model matter is located on the ${rm TeV}$ brane, can be distinguished from other possibilities by its predicted branching fractions into the two modes.
Many charmonium-like and bottomonium-like $XYZ$ resonances have been observed by the Belle, Babar, CLEO and BESIII collaborations in the past decade. They are difficult to fit in the conventional quark model and thus are considered as candidates of e
The exclusive diffractive production of vector mesons and real photons in ep collisions has been studied at HERA in a wide kinematic range. The most recent experimental results are presented.
In the framework of the modified chromo-magnetic interaction model, we perform a systematical study on the mass spectrums of the ground pentaquark states with $qqqqbar{Q}$, $qqqQbar{q}$, $QQQQbar{q}$, $QQQQbar{Q}$, and $QQQqbar{Q}$, $(Q=c,b; q=n,s; n
In this short review we present and discuss all the experimental information about the charged exotic charmonium states, which have been observed over the last five years. We try to understand their properties such as masses and decay widths with QCD
We report measurements of charmonia produced in two-photon collisions and decaying to four-meson final states, where the meson is either a charged pion or a charged kaon. The analysis is based on a 395fb^{-1} data sample accumulated with the Belle de