Studies Of Two-gluon Angular Correlations In Pp Collisions Based On The CGC Framework

In the standard model of particle physics,the proton is composed of quarks and glu-ons,this quarks and gluons is also known as parton with color,the description of the interaction between quarks and gluons is the gauge theory—Quantum Chromodynamics(QCD).The parton density inside the proton will change with the increase of energy or the decrease of Bjorken x,especially the gluon number will increase rapidly with the in-crease of energy.At the same time,the recombination process between the emitted gluons will prevent gluons density increases.The gluonic in the unit phase space is ordered on the short time and disordered system on the long time,to form a new matter,which is called Color Glass Condensate(CGC),the description of the state is the CGC effective field theory(CGC EFT).The nonlinear effect caused by gluon saturation is very important,the CGC EFT provides a uniform description for the nonlinear effect of the initial state of high energy sacttering.The experimental data on proton-proton pp,proton-nucleus(pA)and nucleus-nucleus(AA)collisions at the Relativistic Heavy Ion Collider(RHIC)and Large Hadron Collider(LHC)shows that two particles correlations in long-rang rapidity correlation,near-side(??=0)and away-side(??=?)angular correlation appear Ridge structure.Whether the long-rang rapidity correlation pattern origins from the CGC of initial state in high energy collision?It can help us understand the particle generation and related dynamics mechanism.In theory,CGC EFT can describe the nonlinear effect of gluon saturation on the physical process of small x.The effective degrees of freedom in this framework are color sources at large x and classical gauge fieldsA? at small x which is the solution of classical Yang-Mills equations with a fixed configuration of color sources at an initial scale x0 and its dynamical evolution are captured by the Balitsky-Kovchegov(rcBK)equation with running coupling corrections.In this paper,two-gluon angular correlations were studied the framework CGC EFT,mainly includes the following:Firstly,we studied the dependence of two-gluon long-range rapidity correlations with transverse momentum,results show that:in two-gluon correlation,the selection of trans-verse momentum associated with the saturation scaleQs of collision nucleus.When we selected the transverse momentum of two gluons with p??|QsA+ QsB|,they have the strongest correlation.Below or above the sum of the saturation momentum,the correlation strength will be weakened.Secondly,we studied the two-gluon angular correlations,and showed that the results of the numerical calculation in the framework CGC EFT are in good agreement with the experimental data.When the azimuth in near-side and away-side,the two-gluon correla-tions is the strongest.On the near-side(??= 0)is dominated by Glasma graphs,and on the away-side(??=?)is dominated by the better known BFKL graphs.In this paper,we only calculates the two-gluon correlations under the Glasma graphs.We studied the the impact of the longitudinal rapidity interval on the two-gluon angular correlations,results show that:in the long-rang rapidity area,the two-gluon angular correlations increases with the raise rapidity interval.Finally,we studied the dependence of two-gluon angular correlations with transverse momentum,results show that:when we selected the transverse momentum of two gluons withp??|QsA+ QsB|,they have the strongest correlation.And two-gluon angular corre-lations had a extremum on the azimuth at??= ?/2.We analyzed the angular correlations extremum on??= ?/2,be owning to the rapidity and the transverse momentum selection of unintegrated gluon distribution.