Utilizing PYTHIA we study non-pertubative QCD effects to jet transverse momentum shift in hadronic collisions at the RHIC and the LHC.The dependences of non-perturbative effects such as hadronization corrections and u...Utilizing PYTHIA we study non-pertubative QCD effects to jet transverse momentum shift in hadronic collisions at the RHIC and the LHC.The dependences of non-perturbative effects such as hadronization corrections and underlying event effect on jet radius R,colliding energy,color factor,transverse momentum are investigated by numerical simulations.Hadronization corrections give a negative contribution to the jet energy shift and its magnitude decreases with jet ET and colliding energy √s as well as jet radius R.However,the underlying event effect gives a positive contribution to the jet energy shift and its contribution increases with jet radius and √s.Hadronization and underlying event effect offset each other and could be canceled completely at a specific jet radius dubbed R_(NP)=0.It is observed that R_(NP)=0 decreases with colliding energy √s and is larger for a gluon jet than a quark jet at any fixed ET.展开更多
In this paper,we investigate the medium modifications of girth distributions for inclusive jets and Z^0 tagged jets with a small radius( R=0.2 )in Pb+Pb collisions with √s==2.76 TeV at the LHC.The partonic spectra in...In this paper,we investigate the medium modifications of girth distributions for inclusive jets and Z^0 tagged jets with a small radius( R=0.2 )in Pb+Pb collisions with √s==2.76 TeV at the LHC.The partonic spectra in the initial hard scattering of elementary collisions are obtained by an event generator POWHEG+PYTHIA,which matches the next-to-leading order(NLO)matrix elements with parton showering,and the energy loss of a fast parton traversing the hot/dense QCD medium is calculated by Monte Carlo simulation within the higher-twist formalism of jet quenching in heavy-ion collisions.We present the model calculations of event normalized girth distributions for inclusive jets in p+p and Pb+Pb collisions at √s=2.76 TeV,which give good descriptions of ALICE measurements.It is shown that the girth distributions of inclusive jets in Pb+Pb are shifted to lower girth regions relative to those in p+p.Thus,the nuclear modification factor of girth distributions for inclusive jets is larger than unity at small girth regions and smaller than unity at large girth regions.This behavior results from softer fragments inside a jet as well as the fraction alteration of gluon/quark initiated jets in heavy-ion collisions.We further predict the girth distributions for Z^0 boson tagged jets in Pb+Pb collisions at √s=2.76 TeV and demonstrate that the medium modification on girth distributions for Z^0 tagged jets is less pronounced compared to that for inclusive jets because the dominant components of Z^0 tagged jets are quark-initiated jets.展开更多
基金the New Century Excellent Talent Project(NCET)of the Ministry of Education of China under Grant No NCET-09-0411the National Natural Science Foundation of Chinathe Self-Determined Fund of WUST and CCNU.
文摘Utilizing PYTHIA we study non-pertubative QCD effects to jet transverse momentum shift in hadronic collisions at the RHIC and the LHC.The dependences of non-perturbative effects such as hadronization corrections and underlying event effect on jet radius R,colliding energy,color factor,transverse momentum are investigated by numerical simulations.Hadronization corrections give a negative contribution to the jet energy shift and its magnitude decreases with jet ET and colliding energy √s as well as jet radius R.However,the underlying event effect gives a positive contribution to the jet energy shift and its contribution increases with jet radius and √s.Hadronization and underlying event effect offset each other and could be canceled completely at a specific jet radius dubbed R_(NP)=0.It is observed that R_(NP)=0 decreases with colliding energy √s and is larger for a gluon jet than a quark jet at any fixed ET.
基金Supported by Natural Science Foundation of China(11935007,11805167)。
文摘In this paper,we investigate the medium modifications of girth distributions for inclusive jets and Z^0 tagged jets with a small radius( R=0.2 )in Pb+Pb collisions with √s==2.76 TeV at the LHC.The partonic spectra in the initial hard scattering of elementary collisions are obtained by an event generator POWHEG+PYTHIA,which matches the next-to-leading order(NLO)matrix elements with parton showering,and the energy loss of a fast parton traversing the hot/dense QCD medium is calculated by Monte Carlo simulation within the higher-twist formalism of jet quenching in heavy-ion collisions.We present the model calculations of event normalized girth distributions for inclusive jets in p+p and Pb+Pb collisions at √s=2.76 TeV,which give good descriptions of ALICE measurements.It is shown that the girth distributions of inclusive jets in Pb+Pb are shifted to lower girth regions relative to those in p+p.Thus,the nuclear modification factor of girth distributions for inclusive jets is larger than unity at small girth regions and smaller than unity at large girth regions.This behavior results from softer fragments inside a jet as well as the fraction alteration of gluon/quark initiated jets in heavy-ion collisions.We further predict the girth distributions for Z^0 boson tagged jets in Pb+Pb collisions at √s=2.76 TeV and demonstrate that the medium modification on girth distributions for Z^0 tagged jets is less pronounced compared to that for inclusive jets because the dominant components of Z^0 tagged jets are quark-initiated jets.
