Browsing by Author "Levin, Eugene"

In the paper we develop, in the CGC approach, a new mechanism for quarkonia production in events with high multiplicity of the soft produced particles. In this mechanism both and soft hadrons are produced at short distances , where is the saturation scale, which is considered to be proportional to the multiplicity of soft hadrons. Using this approach, we analyze the vigorously growing multiplicity dependence of quarkonia production, which was recently discovered by the STAR and ALICE collaborations. We demonstrate that this result presents a strong evidence in favor of multigluon fusion mechanisms of the quarkonia states. We analyze in detail the contribution of the 3-gluon fusion mechanism and demonstrate that it describes correctly all the available experimental data on the multiplicity dependence of meson production. We also make predictions for other quarkonia states, such as and , and find that the multiplicity dependence of these states should be similar to that of the meson. Finally, we discuss an experimental setup in which the very strong multiplicity dependence could be observed. This observation would be a strong evidence in favor of the CGC approach.

In this paper we proceed to study the high energy behavior of scattering amplitudes in a simple field model, with the Higgs mechanism for the gauge boson mass. The spectrum of the j-plane singularities of the t-channel partial waves and the corresponding eigenfunctions of the BFKL equation in leading log(1/x) approximation were previously calculated numerically. Here we develop a semiclassical approach to investigate the influence of the exponential decrease of the impact parameter dependence existing in this model, on the high energy asymptotic behavior of the scattering amplitude. This approach is much simpler than our earlier numerical calculations, and it reproduces those results. The analytical (semi-analytical) solutions which have been found in the approximation can be used to incorporate correctly the large impact parameter behavior in the framework of CGC/saturation approach. This behavior is interesting as it provides the high energy amplitude for the electroweak theory, which can be measured experimentally.