No abstract

In the present work, which is based on the k t -factorization framework, it is intended to make a detail study of the isolated prompt-photon pairs (IPPP) production in the high-energy inelastic hadron-hadron collisions differential cross section. The two scheme-dependent unintegrated parton distribution functions (UPDF) in which the angular ordering constraints (AOC) are imposed, namely the Kimber-Martin-Ryskin (KMR) and the Martin-Ryskin-Watt (MRW) approaches, in the leading and the next-to-leading orders (LO and NLO) are considered, respectively. These two prescriptions (KMR and MRW) utilize the phenomenological parton distribution functions (PDF) libraries of Martin et al, i.e. the MMHT2014. The computations are performed in accordance with the initial dynamics of latest existing experimental reports of the D0, CDF, CMS and ATLAS collaborations and the different experimental constraints. It is shown that above frameworks are capable of producing acceptable results, compared to the experimental data, the pQCD and someMonte Carlo calculations (i.e. 2γNNLO, SHERPA, DIPHOX and RESBOS). It is also concluded that the KMR framework produces better results in the higher center-of-mass energies, while the same thing can be argued about the LO-MRW prescription in lower energies. Additionally, these two schemes show different behavior in the regions where the fragmentation and higher pQCD effects become important. A clear prediction for the various shoulders and tails which were detected experimentally are observed and discussed in the present theoretical approaches. The possible double countings between 2→2 and 2→3 processes are studied. Finally, in agreement to the work of Golec-Biernat and Stasto, it is shown that there is not any dispute about the application of the AOC and the cut off, in the above prescriptions at least in the calculation of the various IPPP differential cross sections.

In a series of papers, we have investigated the compatibility of the Kimber-M artin-Ryskin (KM R) and M artin-Ryskin-W att (M RW ) unintegrated parton distribution functions (U P DF ) as well as the description of the experimental data on the proton structure functions. The present work is a sequel to that survey, via calculation of the transverse momentum distribution of the electro-weak gauge vector bosons in the k t -factorization scheme, by the means of the KM R, the LO M RW and the N LO M RW U P DF , in the next-to leading order (N LO).

Quit recently, two sets of new experimental data from the LHCb and the CM S collaborations have been published, concerning the production of the Z 0 vector boson in hadron-hadron collisions with the center-of-mass energy E CM = √ s = 13 T eV . On the other hand, in our recent work, we have conducted a set of N LO calculations for the production of the electroweak gauge vector bosons, utilizing the unintegrated parton distribution functions (U P DF ) in the frameworks of Kimber-M artin-Ryskin (KM R) or M artin-Ryskin-W att (M RW ) and the k t -factorization formalism, concluding that the results of the KM R scheme are arguably better in describing the existing experimental data, coming from D0, CDF , CM S and AT LAS collaborations. In the present work, we intend to follow the same N LO formalism and calculate the rate of the production of the Z 0 vector boson, utilizing the U P DF of KM R within the dynamics of the recent data. It will be shown that our results are in good agreement with the new measurements of the LHCb and the CM S collaborations.

The present work is devoted to study the high-energy QCD events, such as the di-jet productions from proton-proton inelastic collisions at the LHC in the forward-center and the forwardforward configurations, using the unintegrated parton distribution functions (U P DF ) in the k tfactorization framework. The U P DF of Kimber et. al. (KM R) and M artin et.al. (M RW ) are generated in the leading order (LO) and next-to-leading order (N LO), using the Harland − Lang et al. (M M HT 2014) P DF libraries. While working in the forward-center and the forward-forward rapidity sectors, one can probe the parton densities at very low longitudinal momentum fractions (x). Therefore, such a computation can provide a valuable test-field for these U P DF . We find very good agreement with the corresponding di-jet production data available from LHC experiments. On the other hand, as we have also stated in our previous works, (i.e. the protons longitudinal and transverse structure function as well as hadron-hadron LHC W/Z production), the present calculations based on the KM R prescriptions show a better agreement with the corresponding experimental data. This conclusion is achieved, due to the particular visualization of the angular ordering constraint (AOC), despite the fact that the LO−M RW and the N LO−M RW formalisms both employ better theoretical descriptions of the Dokshitzer-Gribov-Lipatov -Altarelli-P arisi (DGLAP ) evolution equation, and hence are expected to produce better results. The form of the AOC in the KM R prescription automatically includes the re-summation of the higher-order ln(1/x) type contributions, i.e. the Balitski-F adin-Kuraev-Lipatov (BF KL) logarithms, in the LO-DGLAP evolution equation. PACS numbers: 12.38.Bx, 13.85.Qk,