kTk_T-factorization approach to the Higgs boson production in ZZ∗→4ℓZZ^*\to 4\ell channel at the LHC

We calculated a differential cross section of the Higgs boson production in the $h\to ZZ^*\to 4\ell$ decay channel within the framework of $k_T$-factorization. Results are obtained using an off-shell matrix element for the $g^*g^*\to h\to ZZ^*\to 4\ell$ process together with Ciafaloni-Catani-Fiorani-Marchesini (CCFM) evolution equations for an unintegrated gluon distribution function. We have presented a comparison of our results with the latest experimental measurements at $\sqrt{S}$ = 8 TeV and $\sqrt{S}$ = 13 TeV from the ATLAS and CMS collaborations at the LHC. In addition to this, we have compared our results with the results from the collinear factorization formalism calculated up to next-to-next-to-leading order plus next-to-next-to-leading logarithm (NNLO + NNLL) accuracy obtained using the HRes code for the Higgs boson production in the gluon-gluon fusion process. Our estimates are consistently close to NNLO + NNLL results obtained using a collinear factorization formalism and are also in agreement with experimental measurements.Comment: 10 pages, 5 figures updated using TMDli

Transverse Single Spin Asymmetries and Charmonium Production

We estimate transverse spin single spin asymmetry(TSSA) in the process $e+p^\uparrow \to J/\psi +X$ using color evaporation model of charmonium production. We take into account transverse momentum dependent(TMD) evolution of Sivers function and parton distribution function and show that the there is a reduction in the asymmetry as compared to our earlier estimates wherein the $Q^2$ - evolution was implemented only through DGLAP evolution of unpolarized gluon densities.Comment: Proceedings of Light Cone 2012, New Delhi, Indi

Single Spin Asymmetry in Charmonium Production

We present estimates of Single Spin Asymmetry (SSA) in the electroproduction of $J/\psi$ taking into account the transverse momentum dependent (TMD) evolution of the gluon Sivers function and using Color Evaporation Model of charmonium production. We estimate SSA for JLab, HERMES, COMPASS and eRHIC energies using recent parameters for the quark Sivers functions which are fitted using an evolution kernel in which the perturbative part is resummed up to next-to-leading logarithms (NLL) accuracy. We find that these SSAs are much smaller as compared to our first estimates obtained using DGLAP evolution but are comparable to our estimates obtained using TMD evolution where we had used approximate analytical solution of the TMD evolution equation for the purpose.Comment: Conference proceedings of Light Cone 2014 at Raleigh, NC, USA. Talk presented by Prof. Anuradha Misra. arXiv admin note: text overlap with arXiv:1411.083

Transverse Single Spin Asymmetry in e+p↑→e+J/ψ+Xe+p^\uparrow \to e+J/\psi +X and Transverse Momentum Dependent Evolution of the Sivers Function

We extend our analysis of transverse single spin asymmetry (SSA) in electroproduction of $J/\psi$ to include the effect of the scale evolution of the transverse momentum dependent (TMD) parton distribution functions and gluon Sivers function. We estimate SSA for JLab, HERMES, COMPASS, and eRHIC energies using the color evaporation model of charmonium production, using an analytically obtained approximate solution of TMD evolution equations discussed in the literature. We find that there is a reduction in the asymmetry compared with our predictions for the earlier case considered by us, wherein the $Q^2$ dependence came only from DGLAP evolution of the unpolarized gluon densities and a different parametrization of the TMD Sivers function was used.Comment: 12 pages, 6 figures. arXiv admin note: text overlap with arXiv:1201.106

Sivers Effect and Transverse Single Spin Asymmetry in e+p↑→e+J/ψ+Xe+p^\uparrow \to e+J/\psi+X

We discuss the possibility of using electroproduction of $J/\psi$ as a probe of gluon Sivers function by measuring single spin asymmetry (SSA) in experiments with transversely polarized protons and electron beams. We estimate SSA for JLab, HERMES, COMPASS and eRHIC energies using the color evaporation model of charmonium production and find asymmetry up to 25% for certain choices of model parameters which have been used earlier for estimating SSA in the SIDIS and Drell-Yan processes

Transverse single spin asymmetry in e plus p up arrow -> e plus J/psi plus X and Q(2) evolution of Sivers function-II

We present estimates of single spin asymmetry in the electroproduction of J/psi taking into account the transverse momentum-dependent (TMD) evolution of the gluon Sivers function. We estimate single spin asymmetry for JLab, HERMES, COMPASS and eRHIC energies using the color evaporation model of J/psi. We have calculated the asymmetry using recent parameters extracted by Echevarria et al. using the Collins-Soper-Sterman approach to TMD evolution. These recent TMD evolution fits are based on the evolution kernel in which the perturbative part is resummed up to next-to-leading logarithmic accuracy. We have also estimated the asymmetry by using parameters which had been obtained by a fit by Anselmino et al., using both an exact numerical and an approximate analytical solution of the TMD evolution equations. We find that the variation among the different estimates obtained using TMD evolution is much smaller than between these on one hand and the estimates obtained using DGLAP evolution on the other. Even though the use of TMD evolution causes an overall reduction in asymmetries compared to the ones obtained without it, they remain sizable. Overall, upon use of TMD evolution, predictions for asymmetries stabilize

Sivers effect and transverse single spin asymmetry in e+p(up arrow) -> e+J/psi+X

We discuss the possibility of using electroproduction of J/psi as a probe of gluon Sivers function by measuring single spin asymmetry (SSA) in experiments with transversely polarized protons and electron beams. We estimate SSA for JLab, HERMES, COMPASS, and eRHIC energies using the color evaporation model of charmonium production and find asymmetry up to 25% for certain choices of model parameters which have been used earlier for estimating SSA in the SIDIS and Drell-Yan processes