Within the framework of a factorization model, we study the behaviour of nuclear modification factor in Au Au collisions at RHIC and Pb-Pb collisions at LHC. We find that the nuclear modification factor is inversely p...Within the framework of a factorization model, we study the behaviour of nuclear modification factor in Au Au collisions at RHIC and Pb-Pb collisions at LHC. We find that the nuclear modification factor is inversely proportional to the radius of the quark-gluon plasma and is dominated by the surface emission of hard jets. We predict the nuclear modification factor R^LHC AA - 0.15 in central Pb-Pb collisions at LHC. The study shows that the factorization model can be used to describe the centrality dependence of nuclear modification factor of the high transverse momentum particles produced in heavy ion collisions at both RHIC and LHC.展开更多
Jet shape measurements are employed to explore the microscopic evolution mechanisms of parton-medium interaction in ultra-relativistic heavy-ion collisions. In this study, jet shape modifications are quantified in ter...Jet shape measurements are employed to explore the microscopic evolution mechanisms of parton-medium interaction in ultra-relativistic heavy-ion collisions. In this study, jet shape modifications are quantified in terms of the fragmentation function F(z), relative momentum p_T^(rel), density of charged particles p(r), jet angularity girth, jet momentum dispersion p_T^(disp),and LeS ub for proton-proton(pp) collisions at 0.9, 2.76. 5.02, 7,and 13 TeV, as well as for lead-lead collisions at 2.76 TeV and 5.02 TeV by JEWEL. A differential jet shape parameter Dgirth is proposed and studied at a smaller jet radius r < 0.3. The results indicate that the medium has the dominant effect on jet shape modification, which also has a weak dependence on the center-of-mass energy. Jet fragmentation is enhanced significantly at very low z < 0.02, and fragmented jet constituents are linearly spread to larger jet-radii for p_T^(rel) < 1. The waveform attenuation phenomena is observed in p_T^(rel),girth, and Dgirth distributions. The results obtained for D_(girth) from pp to Pb + Pb, where the wave-like distribution in pp collision is ahead of Pb + Pb collisions at small jetradii, indicates a strong medium effect.展开更多
Jet measurement is an ideal probe to explore the properties of the hot dense matter created in ultra- relativistic heavy-ion collisions. Recent results at the LHC show that large angle radiation is non-negligible, but...Jet measurement is an ideal probe to explore the properties of the hot dense matter created in ultra- relativistic heavy-ion collisions. Recent results at the LHC show that large angle radiation is non-negligible, but the mechanisms and phenomenology of large angle radiation are still unclear and hotly debated. Considering the coexistence and competition of different physics mechanisms qualitatively, it is assumed that the radiation angle is enhanced randomly over a wide range based on the collinear approximation. Its effects on di-jet momentum imbalance, jet fragmentation function and jet shape are studied in pp collisions at 7 TeV. The results show that di-jet asymmetry is insensitive to large angle radiation, while jet shape and jet fragmentation functions are more sensitive and could explain experimental data well. We conclude that de-collimated radiation cannot be ignored for soft jets, and there is a contribution from large angle radiation （Ф 〉 0.7） of about 8%, which is significant for jet intrinsic structure measurement at PT,jeT 〈80 GeV/c.展开更多
We present a study for matching charged tracks reconstructed from the ALICE tracking detectors with the clusters measured in the photon spectrometer. Matching efficiency and contaminations due to wrong matches have be...We present a study for matching charged tracks reconstructed from the ALICE tracking detectors with the clusters measured in the photon spectrometer. Matching efficiency and contaminations due to wrong matches have been deduced for charged pions and muons. For electrons, the effect of the material in front of PHOS is discussed.展开更多
The analytic expression of proton in deep inelastic scattering is studied by using the color glass condensate model and the dipole picture. We get a better description of the HERA DIS data than the GBW model which was...The analytic expression of proton in deep inelastic scattering is studied by using the color glass condensate model and the dipole picture. We get a better description of the HERA DIS data than the GBW model which was inspired by the Glauber model. We find that our model satisfies the unitarity limit and Froissart Bound which refers to an energy dependence of the total cross-section rising no more rapidly than ln^2 s.展开更多
ALICE,A Large Ion Collider Experiment,is dedicated to study the QCD matter at extreme high temperature and density to understand the Quark Gluon Plasma （QGP） and phase transition.High-transversemomentum photons and ...ALICE,A Large Ion Collider Experiment,is dedicated to study the QCD matter at extreme high temperature and density to understand the Quark Gluon Plasma （QGP） and phase transition.High-transversemomentum photons and neutral mesons from the initial hard scattering of partons can be measured with ALICE calorimeters,PHOS （PHOton Spectrometer） and EMCAL （ElectroMagnetic CALorimeter）.Combing the additional central tracking detectors,the γ-jet and π 0-jet measurements thus can be accessed.These measurements offer us a sensitive tomography probe of the hot-dense medium generated in the heavy ion collisions.In this paper,high p T and photon physics is discussed and the ALICE calorimeters capabilities of high-transverse-momentum neutral mesons and γ-jet measurements are presented.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 10575044 and 10635020, the National Key Basic Research Programme of China under Grant No 2008CB317106, and the Ministry of Education of China under Grant Nos 306022 and IRT0624.
文摘Within the framework of a factorization model, we study the behaviour of nuclear modification factor in Au Au collisions at RHIC and Pb-Pb collisions at LHC. We find that the nuclear modification factor is inversely proportional to the radius of the quark-gluon plasma and is dominated by the surface emission of hard jets. We predict the nuclear modification factor R^LHC AA - 0.15 in central Pb-Pb collisions at LHC. The study shows that the factorization model can be used to describe the centrality dependence of nuclear modification factor of the high transverse momentum particles produced in heavy ion collisions at both RHIC and LHC.
基金Supported by National Natural Science Foundation of China(11505130,11847014,11775097 and CCNU18ZDPY04)
文摘Jet shape measurements are employed to explore the microscopic evolution mechanisms of parton-medium interaction in ultra-relativistic heavy-ion collisions. In this study, jet shape modifications are quantified in terms of the fragmentation function F(z), relative momentum p_T^(rel), density of charged particles p(r), jet angularity girth, jet momentum dispersion p_T^(disp),and LeS ub for proton-proton(pp) collisions at 0.9, 2.76. 5.02, 7,and 13 TeV, as well as for lead-lead collisions at 2.76 TeV and 5.02 TeV by JEWEL. A differential jet shape parameter Dgirth is proposed and studied at a smaller jet radius r < 0.3. The results indicate that the medium has the dominant effect on jet shape modification, which also has a weak dependence on the center-of-mass energy. Jet fragmentation is enhanced significantly at very low z < 0.02, and fragmented jet constituents are linearly spread to larger jet-radii for p_T^(rel) < 1. The waveform attenuation phenomena is observed in p_T^(rel),girth, and Dgirth distributions. The results obtained for D_(girth) from pp to Pb + Pb, where the wave-like distribution in pp collision is ahead of Pb + Pb collisions at small jetradii, indicates a strong medium effect.
基金Supported by National Natural Science Foundation of China(11505130,11775097,IRG1152106,11475068)CTGU(1910103,B2018023)
文摘Jet measurement is an ideal probe to explore the properties of the hot dense matter created in ultra- relativistic heavy-ion collisions. Recent results at the LHC show that large angle radiation is non-negligible, but the mechanisms and phenomenology of large angle radiation are still unclear and hotly debated. Considering the coexistence and competition of different physics mechanisms qualitatively, it is assumed that the radiation angle is enhanced randomly over a wide range based on the collinear approximation. Its effects on di-jet momentum imbalance, jet fragmentation function and jet shape are studied in pp collisions at 7 TeV. The results show that di-jet asymmetry is insensitive to large angle radiation, while jet shape and jet fragmentation functions are more sensitive and could explain experimental data well. We conclude that de-collimated radiation cannot be ignored for soft jets, and there is a contribution from large angle radiation （Ф 〉 0.7） of about 8%, which is significant for jet intrinsic structure measurement at PT,jeT 〈80 GeV/c.
基金Ministry of Science & Technology of China (973:2008CB317106)NSFC (10575044, 10635020)Key Projectof Chinese Ministry of Education (306022, IRT0624)
文摘We present a study for matching charged tracks reconstructed from the ALICE tracking detectors with the clusters measured in the photon spectrometer. Matching efficiency and contaminations due to wrong matches have been deduced for charged pions and muons. For electrons, the effect of the material in front of PHOS is discussed.
基金Supported by NSFC (10875051, 10575044, 10635020)Chinese Ministry of Education (306022, IRT 0624)State Key Development Program of Basic Research of China (2008CB317106)
文摘The analytic expression of proton in deep inelastic scattering is studied by using the color glass condensate model and the dipole picture. We get a better description of the HERA DIS data than the GBW model which was inspired by the Glauber model. We find that our model satisfies the unitarity limit and Froissart Bound which refers to an energy dependence of the total cross-section rising no more rapidly than ln^2 s.
基金Supported partly by the NSFC (10875051,10635020 and 10975061)State Key Development Program of Basic Research of China (2008CB317106)+1 种基金the Key Project of Chinese Ministry of Education (306022 and IRT0624)Program of Introducing Talents of Discipline to Universities of China: B08033
文摘ALICE,A Large Ion Collider Experiment,is dedicated to study the QCD matter at extreme high temperature and density to understand the Quark Gluon Plasma （QGP） and phase transition.High-transversemomentum photons and neutral mesons from the initial hard scattering of partons can be measured with ALICE calorimeters,PHOS （PHOton Spectrometer） and EMCAL （ElectroMagnetic CALorimeter）.Combing the additional central tracking detectors,the γ-jet and π 0-jet measurements thus can be accessed.These measurements offer us a sensitive tomography probe of the hot-dense medium generated in the heavy ion collisions.In this paper,high p T and photon physics is discussed and the ALICE calorimeters capabilities of high-transverse-momentum neutral mesons and γ-jet measurements are presented.
