Boomerang webs up to three-loop order

Webs are sets of Feynman diagrams which manifest soft gluon exponentiation in gauge theory scattering amplitudes: individual webs contribute to the logarithm of the amplitude and their ultraviolet renormalization encodes its infrared structure. In this paper, we consider the particular class of boomerang webs, consisting of multiple gluon exchanges, but where at least one gluon has both of its endpoints on the same Wilson line. First, we use the replica trick to prove that diagrams involving self-energy insertions along the Wilson line do not contribute to the web, i.e. their exponentiated colour factor vanishes. Consequently boomerang webs effectively involve only integrals where boomerang gluons straddle one or more gluons that connect to other Wilson lines. Next we classify and calculate all boomerang webs involving semi-infinite non-lightlike Wilson lines up to three-loop order, including a detailed discussion of how to regulate and renormalize them. Furthermore, we show that they can be written using a basis of specific harmonic polylogarithms, that has been conjectured to be sufficient for expressing all multiple gluon exchange webs. However, boomerang webs differ from other gluon-exchange webs by featuring a lower and non-uniform transcendental weight. We cross-check our results by showing how certain boomerang webs can be determined by the so-called collinear reduction of previously calculated webs. Our results are a necessary ingredient of the soft anomalous dimension for non-lightlike Wilson lines at three loops.

Dynamical interaction geometries for physics with models

The MINT-Wigris Tool bag is presented with its models for color charges as a G-compass the hedgehog for the energy exchange of a nucleon system with its environment, an inner quark-gluon flow in it as 6-roll mill, two nucleon tetrahedrons for the gluon exchange between nucleons quarks, a radial contraction/expansion pulsation for deuteron, two fusion states of the tetrahedrons, a neutrino Gleason operator bound geometry and oscillation dynamics.

Classification of four-point local gluon S-matrices

In this paper, we classify four-point local gluon S-matrices in arbitrary dimensions. This is along the same lines as [1] where four-point local photon S-matrices and graviton S-matrices were classified. We do the classification explicitly for gauge groups SO(N) and SU(N) for all N but our method is easily generalizable to other Lie groups. The construction involves combining not-necessarily-permutation-symmetric four-point S-matrices of photons and those of adjoint scalars into permutation symmetric four-point gluon S-matrix. We explicitly list both the components of the construction, i.e permutation symmetric as well as non-symmetric four point S-matrices, for both the photons as well as the adjoint scalars for arbitrary dimensions and for gauge groups SO(N) and SU(N) for all N. In this paper, we explicitly list the local Lagrangians that generate the local gluon S-matrices for D ≥ 9 and present the relevant counting for lower dimensions. Local Lagrangians for gluon S-matrices in lower dimensions can be written down following the same method. We also express the Yang-Mills four gluon S-matrix with gluon exchange in terms of our basis structures.

Near-threshold photoproduction of $$J/\psi $$ in two-gluon exchange model

The near-threshold photoproduction of $$J/\psi $$ J / ψ is regarded as one golden process to unveil the nucleon mass structure, pentaquark state involving the charm quarks, and the poorly constrained gluon distribution of the nucleon at large x ($$>0.1$$ > 0.1 ). In this paper, we present an analysis of the current experimental data under a two-gluon exchange model, which shows a good consistency. Using a parameterized function form with three free parameters, we have determined the nucleonic gluon distribution at the $$J/\psi $$ J / ψ mass scale. Moreover, we predict the differential cross-section of the electroproduction of $$J/\psi $$ J / ψ as a function of the invariant mass of the final hadrons W, at EicC, as a practical application of the model and the obtained gluon distribution. According to our estimation, hundreds of $$J/\psi $$ J / ψ events can be detected per year on EicC near the threshold. Therefore, the relevant experimental measurements are suggested to be carried out on EicC.

Heavy quarkonium potential at nonzero temperature in the instanton liquid model

Within the framework of the instanton Liquid Model (ILM) we evaluate the heavy quark [Formula: see text] potential at finite temperature. The potential in the ILM has two components: direct instantons contribution and the ILM modified one-gluon exchange contribution. The dynamical ”electric” mass [Formula: see text], which was generated by rescattering of the gluons from the ILM instantons, was taken into account.