Search

We discuss the possibility of quantum entanglement for pairs of charged particles produced in high-energy pp-collisions at the LHC. Using a framework of interacting Wilson lines, we calculate 2D and 1D two-particle angular correlation functions in terms of the differences of the pseudorapidities and azimuthal angles of the produced particles. The calculated near-side angular correlation shows a localized maximum around Δϕ≈0, though it is less pronounced compared to the peak observed by the CMS Collaboration. We argue that this soft correlation is universal and insensitive to the specific properties of the matter (quark-gluon plasma, QCD vacuum, etc.) used to describe hadronic states - though such properties can be included to further improve the results. [ABSTRACT FROM AUTHOR]

We use light-cone QCD sum rules to calculate the pion-photon transition form factor, taking into account radiative corrections up to the next-to-next-to-leading order of perturbation theory. We compare the obtained predictions with all available experimental data from the CELLO, CLEO, and the BaBar Collaborations. We point out that the BaBar data are incompatible with the convolution scheme of QCD, on which our predictions are based, and can possibly be explained only with a violation of the factorization theorem. We pull together recent theoretical results and comment on their significance. [ABSTRACT FROM AUTHOR]

The ultraviolet and rapidity divergences of transverse-momentum dependent parton distribution functions with lightlike and transverse gauge links is studied, also incorporating a soft eikonal factor. We find that in the light-cone gauge with q--independent pole prescriptions extra divergences appear which amount, at one-loop, to a cusp-like anomalous-dimension. We show that such contributions are absent when the Mandelstam-Leibbrandt prescription is used. In the first case, the soft factor cancels the anomalous dimension defect, while in the second case its ultraviolet-divergent part reduces to unity. [ABSTRACT FROM AUTHOR]

We discuss the QCD sum-rule approach for the spacelike electromagnetic pion form factor in the O(αs) approximation. We show that the nonlocality of the condensates is a key point to include nonperturbative contributions to the pion form factor. We compare our results with the Local-Duality predictions and show that the continuum threshold s0(Q2) parameter is highly underestimated in the Local-Duality approach at Q2 ≳ 2 GeV2. Using our fit for this parameter, $s_0^{{\rm{LD}}} (Q^2 )$ and applying the fractional analytic perturbation theory, we estimate with an accuracy of the order of 1% the $O(\alpha _s^2 )$ contribution to the pion's form factor. [ABSTRACT FROM AUTHOR]