Open-string singlet interaction as pomeron in elastic $pp, p\bar{p}$ scattering

We consider contributions of the open-string singlet~(OSS) interaction to the proton-proton scattering. Modelling baryon and meson as instanton and open string in the effective QCD string model, the typical pomeron is identified with a massive spin-2 closed string. According to the open-closed string duality, the massive spin-2 closed string is accompanied by the open-string singlet interaction with universal coupling. The flat space 4-point open-string singlet amplitudes and cross sections are computed in the Regge limit. Including both the open and closed string pomerons, we fit the differential cross-section with experimental data of the proton-proton and proton-antiproton scattering from the CDF, E-710, D0, LHC-ATLAS and LHC-TOTEM collaborations. The fitting results show the universality of the string mass scale~(or string tension) and consistency of the string model between the open and closed string parameters in describing the $pp$ and $p\bar{p}$ scattering in the Regge limit. The fitting of the string model to experimental data gives the string scale $M_{S}\simeq 1.7-1.8$ GeV and the corresponding glueball pole mass $m_{g}\simeq 1.6-1.7$ GeV. This lies within experimental values of the observed $2^{++}, I=0$ "meson" masses.