This article reports measurements of the $p_{\rm{T}}$-differential inclusive jet cross-section in pp collisions at $\sqrt{s}$ = 5.02 TeV and the $p_{\rm{T}}$-differential inclusive jet yield in Pb-Pb 0-10% central collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV. Jets were reconstructed at mid-rapidity with the ALICE tracking detectors and electromagnetic calorimeter using the anti-$k_{\rm{T}}$ algorithm. For pp collisions, we report jet cross-sections for jet resolution parameters $R=0.1-0.6$ over the range $20<p_{\rm{T,jet}}<140$ GeV/$c$, as well as the jet cross-section ratios of different $R$, and comparisons to two next-to-leading-order (NLO)-based theoretical predictions. For Pb-Pb collisions, we report the $R=0.2$ and $R=0.4$ jet spectra for $40<p_{\rm{T,jet}}<140$ GeV/$c$ and $60<p_{\rm{T,jet}}<140$ GeV/$c$, respectively. The scaled ratio of jet yields observed in Pb-Pb to pp collisions, $R_{\rm{AA}}$, is constructed, and exhibits strong jet quenching and a clear $p_{\rm{T}}$-dependence for $R=0.2$. No significant $R$-dependence of the jet $R_{\rm{AA}}$ is observed within the uncertainties of the measurement. These results are compared to several theoretical predictions.
We present multiplicity and pseudorapidity distributions of inclusive photons at forward rapidity in proton-lead (p-Pb) collisions at $\sqrt{s\rm_{NN}}$ = 5.02 TeV using the data obtained from Photon Multiplicity Detector (PMD) of ALICE. The centrality dependence of pseudorapidity distributions of inclusive photons is also studied. Results are compared with the previous ALICE measurements of charged-particle production and with theoretical predictions from Monte Carlo models, DPMJET and HIJING.
We report on the performance studies of two correction methods, namely the efficiency-purity method and the Bayesian unfolding method applied to the pseudorapidity distribution of photons. The pseudorapidity distribution of inclusive photons at forward rapidities in the range \mbox{\small $(2.3<η<3.9)$} in p\textendash Pb collisions at $\sqrt{\it{s}_{\rm{NN}}} = 8.16$ TeV is obtained with the HIJING Monte Carlo event generator. The simulated data samples were obtained from the Photon Multiplicity Detector (PMD) in ALICE.
Inclusive J/$ψ$ production is studied in Xe-Xe interactions at a centre-of-mass energy per nucleon pair of $\sqrt{s_{\rm NN}}= 5.44$ TeV, using the ALICE detector at the CERN LHC. The J/$ψ$ meson is reconstructed via its decay into a muon pair, in the centre-of-mass rapidity interval $2.5<y<4$ and down to zero transverse momentum. In this Letter, the nuclear modification factors $R_{\rm AA}$ for inclusive J/$ψ$, measured in the centrality range 0-90% as well as in the centrality intervals 0-20% and 20-90% are presented. The $R_{\rm AA}$ values are compared to previously published results for P…
We report on the measurement of the inclusive J/$ψ$ polarization parameters in pp collisions at a center of mass energy $\sqrt{s} = 8$ TeV with the ALICE detector at the LHC. The analysis is based on a data sample corresponding to an integrated luminosity of 1.23 pb$^{-1}$. J/$ψ$ resonances are reconstructed in their di-muon decay channel in the rapidity interval $2.5 < y < 4.0$ and over the transverse-momentum interval $2 < p_{\rm T} < 15$ GeV/$c$. The three polarization parameters ($λ_θ$, $λ_φ$, $λ_{θφ}$) are measured as a function of $p_{\rm T}$ both in the helicity and Collins-Soper refere…
The production cross section of inclusive isolated photons has been measured by the ALICE experiment at the CERN LHC in pp collisions at a centre-of-momentum energy of $\sqrt{s}=$ 7 TeV. The measurement is performed with the electromagnetic calorimeter EMCal and the central tracking detectors, covering a range of $|η|<0.27$ in pseudorapidity and a transverse momentum range of $ 10 < p_{\rm T}^γ < $ 60 GeV/$c$. The result extends the $p_{\rm T}$ coverage of previously published results of the ATLAS and CMS experiments at the same collision energy to smaller $p_{\rm T}$. The measurement is compa…
A measurement of the inclusive b-jet production cross section is presented in pp and p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV, using data collected with the ALICE detector at the LHC. The jets were reconstructed in the central rapidity region $|η|<0.5$ from charged particles using the anti-$k_{\rm T}$ algorithm with resolution parameter $R=0.4$. Identification of b jets exploits the long lifetime of b hadrons, using the properties of secondary vertices and impact parameter distributions. The $p_{\rm T}$-differential inclusive production cross section of b jets, as well as the correspo…
Inclusive J/$ψ$ production is studied in minimum-bias proton-proton collisions at a centre-of-mass energy of $\sqrt{s}$ = 5.02 TeV by ALICE at the CERN LHC. The measurement is performed at mid-rapidity ($|y| < 0.9$) in the dielectron decay channel down to zero transverse momentum $p_{\rm T}$, using a data sample corresponding to an integrated luminosity of $L_{\rm int} = 19.4 \pm$ 0.4 nb$^{-1}$. The measured $p_{\rm T}$-integrated inclusive J/$ψ$ production cross section is d$σ$/d$y$ = 5.64 $\pm$ 0.22 (stat.) $\pm 0.33$ (syst.) $\pm 0.12$ (lumi.) $μ$b. The $p_{\rm T}$-differential cross sectio…
A study of multiplicity and pseudorapidity distributions of inclusive photons measured in pp and p$-$Pb collisions at a center-of-mass energy per nucleon$-$nucleon collision of $\sqrt{s_{\rm NN}} = 5.02$ TeV using the ALICE detector in the forward pseudorapidity region $2.3 < η_{\rm lab} < 3.9$ is presented. Measurements in p$-$Pb collisions are reported for two beam configurations in which the directions of the proton and lead ion beam were reversed. The pseudorapidity distributions in p$-$Pb collisions are obtained for seven centrality classes which are defined based on different event activ…
Measurements of the yield and nuclear modification factor, $R_\mathrm{ AA}$, for inclusive jet production are performed using 0.49 nb$^{-1}$ of Pb+Pb data at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV and 25 pb$^{-1}$ of $pp$ data at $\sqrt{s}=5.02$ TeV with the ATLAS detector at the LHC. Jets are reconstructed with the anti-$k_t$ algorithm with radius parameter $R=0.4$ and are measured over the transverse momentum range of 40-1000 GeV in six rapidity intervals covering $|y|<2.8$. The magnitude of $R_\mathrm{ AA}$ increases with increasing jet transverse momentum, reaching a value of approximately 0.6 …
Inclusive J/$ψ$ production is studied in p-Pb interactions at a centre-of-mass energy per nucleon-nucleon collision $\sqrt{s_{\rm NN}}=8.16$ TeV, using the ALICE detector at the CERN LHC. The J/$ψ$ meson is reconstructed, via its decay to a muon pair, in the centre-of-mass rapidity intervals $2.03<y_{\rm {cms}}<3.53$ and $-4.46<y_{\rm {cms}}<-2.96$, where positive and negative $y_{\rm {cms}}$ refer to the p-going and Pb-going direction, respectively. The transverse momentum coverage is $p_{\rm T}<20$ GeV/$c$. In this paper, $y_{\rm cms}$- and $p_{\rm T}$-differential cross sections for inclusi…
Jet production in high energy proton-proton ($p+p$) collisions is dominated by hard QCD subprocesses such as gluon-gluon and quark-gluon scatterings. Therefore $p+p$ is an effective tool to probe the internal distribution of gluons in the proton. The STAR Collaboration at the Relativistic Heavy Ion Collider (RHIC) is using longitudinally polarized $p+p$ collisions at the center of mass energies, $\sqrt{s} = $ 200 and 510 GeV, to study the cross-section and double spin asymmetries, $A_{LL}$, of inclusive jet and di-jet production. The measurements at $\sqrt{s} = $ 200 GeV showed that the jet cr…
The self-normalised $ψ(2S)$ yields as a function of charged-particle multiplicity in pp collisions at $\sqrt{s}$ = 13 TeV and p--Pb collisions at $\sqrt{s_{\mathrm{NN}}}$= 8.16 TeV, using the ALICE detector at the CERN LHC, are reported in these proceedings. This measurement represents one of the main tools to understand the role of multiparton interactions and their influence on charmonium production in small systems, i.e pp and pA collisions. The ratio of $ψ(2S)$-over-J/$ψ$ as a function of charged-particle multiplicity is also presented for both pp and p--Pb collisions. The comparison to th…
The ALICE Collaboration reports the measurement of semi-inclusive distributions of charged-particle jets recoiling from a high-transverse momentum trigger hadron in p-Pb collisions at $\sqrt{s_{\rm NN}} =5.02$ TeV. Jets are reconstructed from charged-particle tracks using the anti-$k_{\rm T}$ algorithm with resolution parameter $R=0.2$ and $0.4$. A data-driven statistical approach is used to correct the uncorrelated background jet yield. Recoil jet distributions are reported for jet transverse momentum $15<p_{\rm T,jet}^{\rm ch} <50$ GeV/$c$ and are compared in various intervals of p-Pb event …
Inclusive jet spectra in 2.76 TeV collisions from ALICE
在RHIC上对重离子碰撞中高pT粒子产生的测量表明，介质引起的能量损失影响重离子碰撞早期产生的部分子。在LHC能量下，部分子初始产生截面的增加使得完全重构的喷流在很宽的运动学范围内可用，这允许对部分子能量损失进行更多的差分研究。部分子能量损失使我们能够获得在重离子碰撞中产生的热的非限定核物质的关键观测值。利用ALICE跟踪探测器和电磁量能器重建的喷流的包含截面是从2.76 TeV pp运行期间收集的数据中给出的。用于重建喷流和提取它们从铅铅碰撞的波动背景的程序进行了讨论。
Reference heavy flavour cross sections in pp collisions at sqrt(s) = 2.76 TeV, using a pQCD-driven sqrt(s)-scaling of ALICE measurements at sqrt(s) = 7 TeV
These proceedings report on measurements of the jet spectrum and nuclear modification factor for inclusive full jets (containing both charged and neutral constituents) in Pb-Pb and pp collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV recorded with the ALICE detector. These measurements use a machine learning based background correction, which reduces residual fluctuations. This method allows for measurements to lower transverse momenta and larger jet resolution parameter (R) than previously possible in ALICE. In this method, machine learning techniques are used to correct the jet transverse momentu…
We report the first measurement of fully corrected semi-inclusive charged recoil jets for both direct-photon ($γ_{dir}$) and $π^{0}$ triggers, within two trigger transverse energy ranges between 9 GeV and 15 GeV, in central Au+Au collisions at $\sqrt {s_{\rm NN}}$ = 200 GeV using data with an integrated luminosity of 13 $\rm nb^{-1}$ collected by the STAR experiment. A comparison between $π^{0}$-triggered recoil jets in p+p collisions and PYTHIA is discussed. A comparison is also presented between the suppression of $γ_{dir}$- and $π^{0}$-triggered recoil jets in central Au+Au collisions with …
High $p_{T}$ inclusive hadron and photon spectra in pp and PbPb collisions
本文报道了在大型强子对撞机上用CMS探测器测量的$\sqrt{s_{NN}}=2.76$ TeV PbPb碰撞中的带电强子和孤立光子谱。带电粒子的动量谱相比，质子-质子碰撞在$\sqrt{s}=2.76$ TeV的构造参考测量通过使用$x_T$缩放和直接插值在固定的$p_{T}$的组合。光子的结果进行了比较，在相同的质心的能量下的下一个领先的顺序计算。计算了核修饰因子（$R_{AA}$），研究了介质的性质。虽然在高横向动量的带电粒子$R_{AA}$中观察到较大的抑制，但孤立光子没有显示出任何修改，这表明在$\sqrt{s_{NN}}=2.76$ TeV的PbPb碰撞产生强烈相互作用的有色介质。
