The t-channel exchange of a first generation leptoquark could contribute to the cross section for qq → e + e − . The leptoquark is off-shell, so this process can be sensitive to leptoquarks beyond the mass reach of pair production searches at the LHC (currently m LQ > 830 GeV). We attempt to analytically translate ATLAS bounds on (qγ μ q)(ēγ μ e) contact interactions to the various scalar leptoquarks, we but encounter two difficulties: the leptoquark momentum is not negligible, and the leptoquarks do not induce the contact interaction studied by ATLAS, so the interference with the standard model is different. If bounds were quoted on the functional dependence of the cross section onŝ, rather than on particular contact interaction models, these difficulties could be circumvented. We use the results of such a "form factor" fit to CMS plots to obtain bounds on the various leptoquarks' quark-lepton coupling of order λ 2 (m LQ /3 TeV) 2 .

Fundamental properties of finite two-dimensional (2D) Yukawa dust clusters, subjected to power law confining potentials, are studied using Monte Carlo simulations. We show the effects of the interplay between the Yukawa screening and the functional form of the confining potential on the structure, dynamics, and melting of few particle systems. We find numerically that one of the fundamental eigenmodes, namely, a center of mass mode, still exists for a confinement with n = 3. The stability of such clusters is discussed using the variance of the block averaged interparticle distance fluctuations (VIDF). The melting temperatures are found to depend crucially on screening length and confinement power. For the estimation of the melting temperature, the VIDF quantity is believed to be reliable only for well-packed structures, where the relative interparticle distance fluctuations (IDF) disregard the melting transition point.