UTTACセミナー 2017年9月1日(金)




日時:2017年9月1日(金) 13時~
場所:共同研究棟C 大会議室(305室)

氏名:横山 広樹 (Hiroki Yokoyama)
所属:数理物質科学研究科 博士後期課程3年

Measurement of jet spectra reconstructed with charged particles in Pb-Pb collisions at sqrt(s_NN) = 5.02 TeV with the ALICE detector at the LHC

(LHC-ALICE実験 sqrt(s_NN) = 5.02 TeV 鉛鉛衝突実験における荷電粒子ジェットの測定)


Nuclear matter at extremely high densities and/or temperatures, so-called Quark-Gluon Plasma,
formed by quarks and gluons with mostly liberated degrees of freedom as predicted by QCD,
is believed to have filled the early universe during its QCD epoch with relics still observable today.
In laboratory, high-energy heavy ion collisions offer the only possibility to recreate such QGP droplets
experimentally. To characterize the dense QCD matter produced in central collisions of relativistic heavy nuclei,
jets have proven to be excellent tools. Jet production has indeed been observed to be attenuated in the
presence of a QGP. Our theoretical picture of this jet quenching mechanism as pQCD energy loss of hard
partons strongly interacting with the medium has considerably progressed since the advent of the LHC era.

In this seminar, I will present my contribution towards quantifying jet quenching at the LHC.
Firstly we show the performance of newly developed and successfully commissioned Level-1 jet trigger
algorithm for the LHC Run 2 started in 2015. Secondly we present the results of jet
spectra measurements reconstructed with charged particles in Pb-Pb collisions at the highest
collision energy at sqrt(s_NN) = 5.02 TeV with ALICE detector. We also measure the nuclear
modification factors of jets in Pb-Pb at this energy, and compared with the previous results
at the lower energy. The physics implications by these measurements are discussed.