The doubly charmed $$\Xi _{cc}^{++} (ccu)$$Ξcc++(ccu) state is the only listed baryon in PDG, which was discovered in the experiment. The LHCb collaboration gets closer to discovering the second doubly charmed baryon $$\Xi _{cc}^{+} (ccd)$$Ξcc+(ccd), hence the investigation of the doubly charmed/bottom baryons from many aspects is of great importance that may help us not only get valuable knowledge on the nature of the newly discovered states, but also in the search for other members of the doubly heavy baryons predicted by the quark model. In this context, we investigate the strong coupling constants among the $$\Xi _{cc}^{+(+)}$$Ξcc+(+) baryons and $$\pi ^{0(\pm )}$$π0(±) mesons by means of light cone QCD sum rule. Using the general forms of the interpolating currents of the $$\Xi _{cc}^{+(+)}$$Ξcc+(+) baryons and the distribution amplitudes (DAs) of the $$\pi $$π meson, we extract the values of the coupling constants $$g_{\Xi _{cc} \Xi _{cc} \pi }$$gΞccΞccπ. We extend our analyses to calculate the strong coupling constants among the partner baryons with $$\pi $$π mesons, as well, and extract the values of the strong couplings $$g_{\Xi _{bb} \Xi _{bb} \pi }$$gΞbbΞbbπ and $$g_{\Xi _{bc} \Xi _{bc} \pi }$$gΞbcΞbcπ. The results of this study may help experimental groups in the analyses of the data related to the strong coupling constants among the hadronic multiplets.

In most non-perturbative methods in hadron physics the calculations are started with a correlation function in terms of some interpolating and transition currents in x-space. For simplicity, the calculations are then transformed to the momentum space by a Fourier transformation. To suppress the contributions of the higher states and continuum; and enhance the ground state contribution, Borel transformation as well as continuum subtraction are applied by the help of quark-hadron duality assumption. In the present study we work out the mathematics required for these processes in the case of light and multiheavy hadrons. We address a well-known problem in subtraction of the effects of the higher states and continuum and discuss how we find finite results without any divergence by using an appropriate representation of the modified Bessel functions, appearing in the heavy quark propagator, and successive applications of the Borel transformations, which lead to more suppression of the higher states and continuum contributions. The results obtained can be used in determination of the spectroscopic and decay properties of the multi-heavy standard and non-conventional (exotic) systems in many non-perturbative methods, specially the QCD sum rules. *

We present a comparative analysis of the impact of the non-perturbative intrinsic charm quark content of the proton on differential cross section of γ + c-jet in pp and pp collisions, for the kinematic regions that are sensitive to this contribution. We discuss the Q 2 evolution of intrinsic quark distributions at the next-to-leading order (NLO) and present a code which provide these distributions as a function of x and Q 2 for any arbitrary Fock state probability. For the pp collisions at the Tevatron, the results are compared with the recent experimental data of D0 at √ s = 1.96 TeV and also predictions for pp collisions at √ s = 8 TeV and √ s = 13 TeV for the LHC.

An accurate knowledge of nuclear parton distribution functions (nPDFs) is an essential ingredient of high energy physics calculations when the processes are involving nuclei in the initial state. It is well known now that the prompt photon production both in hadronic and nuclear collisions is a powerful tool for exploring the parton densities in the nucleon and nuclei especially of the gluon. In this work, we are going to perform a comprehensive study of the isolated prompt photon production in p-Pb collisions at backward rapidities to find the best kinematic regions in which the experimental measurements have most sensitivity to the nuclear modifications of parton densities.Most emphasis will be placed on the antishadowing nuclear modification. To this aim, we calculate and compare various quantities at different values of center-of-mass energy covered by the LHC and also different rapidity regions to realize which one is most useful.Besides the parton distribution functions (PDFs), whether unpolarized [1][2][3][4][5][6][7][8][9][10][11] or polarized [12][13][14][15][16][17][18], and fragmentation functions (FFs) [19][20][21][22][23], the nuclear modifications of PDFs [24][25][26][27][28][29][30][31] are also important ingredients of high energy physics calculations, in particular, for processes involving nuclei in the initial state. In fact, without having nuclear PDFs (nPDFs) which describe the structure of the colliding nuclei, the theoretical calculation of the cross sections in any nuclear collision will not be possible. Thanks to the collinear factorization theorem [32,33], the nPDFs can be extracted just in a way similar to the PDFs determination through a global analysis of nuclear experimental data. Nowadays, due to many developments achieved in the phenomenological approaches, theoretical calculations and experimental measurements, the PDFs are well determined in a wide range of the momentum fraction x. However, the situation is not very satisfying for the case of nPDFs because of the lack of experimental data.Although the main experimental data for constraining nPDFs come from the old fixedtarget deep inelastic scattering (DIS) and proton-nucleus Drell-Yan (DY) dilepton production experiments, there are some analyses in which the neutrino DIS data have also been used [25,27,30]. Furthermore, the inclusive pion production from d-Au collisions at RHIC that can be considered as another source to put further constraints on the nuclear gluon distribution is usually used in the nPDFs analyses [26][27][28]30]. Recently, EPPS16 [30] has also included, for the first time, the fixed-target DY data in pion-nucleus collisions and new LHC proton-lead (p-Pb) data on dijet and heavy gauge-boson production. There are also some studies show that important information about nPDFs can be achieved by analyzing the prompt photon production in nuclear collisions [34][35][36][37][38][39], jet and dijet photoproduction measurements at a future electron-ion collider (EIC) [40,41], single inclusive jet production at very forwa...

The recent measurement of the differential γ + c-jet cross section, performed at the Tevatron collider in Run II by the D0 collaboration, is studied in a next-to-leading order (NLO) global QCD analysis to assess its impact on the proton parton distribution functions (PDFs). We show that these data lead to a significant change in the gluon and charm quark distributions. We demonstrate also that there is an inconsistency between the new high precision HERA I+II combined data and Tevatron measurement. Moreover, in this study we investigate the impact of older EMC measurements of charm structure function F 2 c on the PDFs and compare the results with those from the analysis of Tevatron data. We show that both of them have the same impact on the PDFs, and thus can be recognized as the same evidence for the inefficiency of perturbative QCD in dealing with charm production in some kinematic regions.