Estimation of Bjorken Initial Energy Density in pp Collisions

Initial energy density produced in ultrarelativistic hadronic and heavy-ion collisions is an important quantity for characterisation of the system created in these collisions. In this work the Bjorken initial energy density is estimated in proton-proton collisions at \(\sqrt{s} = 5.02, 7\) and 13 TeV for both minimum bias and different multiplicity classes with a new method using experimental data for proton radius R = 0.89 fm taken from electron proton scattering and taking the area of overlap region of collisions as \(\pi R^{2}\) . The same quantity has also been calculated for minimum bias pp collisions only for \(\sqrt{s} = 0.9, 2.76\) and 8 TeV. It is observed that the Bjorken initial energy density in pp collisions in higher multiplicity classes for the above mentioned collision energies reach the value that is obtained in case of Pb-Pb collisions at \(\sqrt{s_{NN}} = 2.76\) TeV and 5.02 TeV. The results obtained in this work are also compared to those reported earlier for \(\sqrt{s} = 7\) TeV that uses the overlap area obtained from Gaussian scattering density profile \(\pi R^{2} = \frac{\sigma _{tot}^{2}}{4\sigma _{el}}\) and \(R = \) 1.76 fm.