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Correlations and flavors in jets in ALICE  [PDF]
Filip Krizek
Physics , 2015,
Abstract: We report on the measurement of hadron composition in charged jets in pp at $\sqrt{s}=7$ TeV and show the first data on particle type dependent jet fragmentation at the LHC. Further, we present $(\Lambda+\bar{\Lambda})/2$K$^{0}_{\mathrm{S}}$ ratios measured in charged jets in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 2.76$ TeV and in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV. While the ratio of the inclusive $p_{\mathrm{T}}$ spectra of $\Lambda$ and K$^{0}_{\mathrm{S}}$ exhibits centrality dependent enhancement both in Pb-Pb and p-Pb system, the $(\Lambda+\bar{\Lambda})/2$K$^{0}_{\mathrm{S}}$ ratio measured in charged jets reveals that jet fragmentation does not contribute to the observed baryon anomaly. Finally, we discuss the measurement of semi-inclusive $p_{\mathrm{T}}$ spectra of charged jets that recoil from a high-$p_{\mathrm{T}}$ hadron trigger in Pb-Pb and pp collisions at $\sqrt{s_{\mathrm{NN}}} = 2.76$ TeV and $\sqrt{s} = 7$ TeV, respectively. The jet yield uncorrelated with the trigger hadron is removed at the event-ensemble level without introducing a bias on the jet population which is therefore infrared and collinear safe. The recoil jet yield in central Pb-Pb is found to be suppressed w.r.t. that from pp PYTHIA reference. On the other hand, there is no sign of intra-jet broadening even for anti-$k_{\mathrm{T}}$ jets with a resolution parameter as large as $R=0.5$.
Parton and Hadron Correlations in Jets  [PDF]
Rudolph C. Hwa,Zhiguang Tan
Physics , 2005, DOI: 10.1103/PhysRevC.72.024908
Abstract: Correlation between shower partons is first studied in high $p_T$ jets. Then in the framework of parton recombination the correlation between pions in heavy-ion collisions is investigated. Since thermal partons play very different roles in central and peripheral collisions, it is found that the correlation functions of the produced hadrons behave very differently at different centralities, especially at intermediate $p_T$. The correlation function that can best exhibit the distinctive features is suggested. There is not a great deal of overlap between what we can calculate and what has been measured. Nevertheless, some aspects of our results compare favorably with experimental data.
Double Scaling of Angular Correlations inside Jets  [PDF]
Wolfgang Ochs,Jacek Wosiek
Physics , 1995,
Abstract: Angular correlations of partons have been derived for high energy jets in QCD. Interesting new scaling properties with two redundant variables (jet energy $P$ and jet opening angle $\Theta$) emerge which can be tested within a parton-hadron duality picture. Recent results from LEP support the scaling in $\Theta$; the scaling in both $P$ and $\Theta$ could be tested with jets from deep inelastic scattering or with high $p_T$ jets.
Energy Conservation Constraints on Multiplicity Correlations in QCD Jets  [PDF]
J. -L. Meunier,R. Peschanski
Physics , 1996, DOI: 10.1007/s002880050287
Abstract: We compute analytically the effects of energy conservation on the self-similar structure of parton correlations in QCD jets. The calculations are performed both in the constant and running coupling cases. It is shown that the corrections are phenomenologically sizeable. On a theoretical ground, energy conservation constraints preserve the scaling properties of correlations in QCD jets beyond the leading log approximation.
Hadron Correlations in Jets and Ridges through Parton Recombination  [PDF]
Rudolph C. Hwa
Physics , 2009,
Abstract: Hadron correlations in jets, ridges and opposite dijets at all $p_T$ above 2 GeV/c are discussed. Since abundant data are available from RHIC at intermediate $p_T$, a reliable hadronization scheme at that $p_T$ range is necessary in order to relate the semihard partonic processes to the observables. The recombination model is therefore first reviewed for that purpose. Final-state interaction is shown to be important for the Cronin effect, large B/M ratio and forward production. The effect of semihard partons on the medium is then discussed with particular emphasis on the formation of ridge with or without trigger. Azimuthal anisotropy can result from ridges without early thermalization. Dynamical path length distribution is derived for any centrality. Dihadron correlations in jets on the same or opposite side are shown to reveal detail properties of trigger and antitrigger biases with the inference that tangential jets dominate the dijets accessible to observation.
Newly Developed Empirical Correlations for Simulation of Transitional Flows  [PDF]
Reza Taghavi Zenouz,Majed Etemadi
Advances in Mechanical Engineering , 2013, DOI: 10.1155/2013/763197
Abstract: An effective new formulation is developed for simulation of transitional flows. This formulation is based on modifications made to the latest numerical model utilizing vorticity and momentum thickness Reynolds numbers concepts. In this respect, rigorous experiments were conducted in a wind tunnel to modify the existing formulation to a more reliable form suitable for modeling of transitional flows. Test model was a linear cascade of axial compressor blades. Wind tunnel tests consisted of measurements of surface pressure distributions and velocity profiles utilizing hot film anemometry. Different freestream turbulence intensities, flow incidences, and Reynolds numbers were examined. New correlations were imposed to a commercial numerical flow solver; applying them to some standard objects produced more reliable results than those obtained from other formulations, presented so far. This attribution is more emphasized especially while dealing with modeling laminar separation bubbles, where transition occurs within the free shear layer. 1. Introduction Numerical simulation of transitional flows has gained increasing attention in the recent years. Treating transition in common approaches, like RANS method (Reynolds averaged Navier-Stokes equations), involves two major aspects of determination of its precise position and modeling the laminar to turbulent transition regions. Generally speaking, apart from simply taking measured values from experiments, approximate location of transition can be derived from empirical correlations [1]. The only transition models which are comparable with modern CFD methods can be referred to low Reynolds number ones. These models rely entirely on the capability of wall damping terms to capture the effects of transition. They are also expected to only simulate bypass transition which is dominated by diffusion effects from the freestream. Formulations of these models still exhibit a close connection between the viscous sublayer behavior and the transition calibration process. Recalibration of even one function encountered in these types of methods may change their whole performance. It is therefore not possible to introduce experimental information without a substantial reformulation of the entire model. It should be noted that although this formulation seems to be rather efficient, experimental results have shown that other factors like freestream turbulence intensity, streamwise pressure gradient and wall roughness may affect the transition [1–3]. As a result, damping functions could not reliably predict such a different and
BFKL Effects in Azimuthal Angle Correlations of Forward Jets
Vera, Agustin Sabio;Schwennsen, Florian
High Energy Physics - Phenomenology , 2007,
Abstract: The azimuthal angle correlation of Mueller-Navelet jets at hadron colliders is studied in the NLO BFKL formalism. We highlight the need of collinear improvements in the kernel to obtain good convergence properties and we obtain better fits for the Tevatron data than at LO accuracy. We also estimate these correlations for larger rapidity differences available at the LHC.
Influence of quenched jets on di-hadron correlations  [PDF]
Jiangyong Jia,Roy Lacey
Physics , 2008, DOI: 10.1103/PhysRevC.79.011901
Abstract: A simple jet absorption model is used to study the influence of hadron pairs produced by quenched jets, on di-hadron angular correlations at intermediate transverse momentum ($p_T$). We demonstrate that such pairs can dominate both the yield and the shape of angular correlations, and may account for the similar properties between the near-side "ridge" and the away-side "double-humped" structure seen in recent data. These hadron pairs also show azimuthal anisotropy which is sensitive to the emission angle of hadrons relative to that of the jet. Measurement of this anisotropy may provide a constraint for elucidating the production mechanism for near- and away-side hadron pairs at intermediate $p_T$.
Large-scale jets in the magnetosheath and plasma penetration across the magnetopause: THEMIS observations  [PDF]
A. V. Dmitriev,A. V. Suvorova
Physics , 2015, DOI: 10.1002/2014JA020953
Abstract: THEMIS multi-point observation of the plasma and magnetic fields, conducted simultaneously in the dayside magnetosheath and magnetosphere, were used to collect 646 large-scale magnetosheath plasma jets interacting with the magnetopause. The jets were identified as dense and fast streams of the magnetosheath plasma whose energy density is higher than that of the upstream solar wind. The jet interaction with the magnetopause was revealed from sudden inward motion of the magnetopause and an enhancement in the geomagnetic field. The penetration was determined as appearance of the magnetosheath plasma against the background of the hot magnetospheric particle population. We found that almost 60% of the jets penetrated through the magnetopause. Vast majority of the penetrating jets was characterized by high velocities V > 220 km/s and kinetic bk > 1 that corresponded to a combination of finite Larmor radius effect with a mechanisms of impulsive penetration. The average plasma flux in the penetrating jets was found to be 1.5 times larger than the average plasma flux of the solar wind. The average rate of jet-related penetration of the magnetosheath plasma into the dayside magnetosphere was estimated to be ~10^29 particles per day. The rate varies highly with time and can achieve values of 1.5*10^29 particles per hour that is comparable with estimates of the total amount of plasma entering the dayside magnetosphere.
Deflected Jets or Hot Spots? Conical Correlations of Hard Trigger Particles  [cached]
Betz B.
EPJ Web of Conferences , 2011, DOI: 10.1051/epjconf/20111307002
Abstract: The double-peak structure observed in soft-hard dihadron correlations was recently studied intensively in order to learn more about the jet-induced medium excitation in ultrarelativistic heavy-ion collisions. Experimental data shows that the double-peak structure obtained for soft trigger particles coalesces into one peak for harder trigger particles. We demonstrate that this effect occurs when averaging over many jet events in a transversally expanding background, while a hot spot scenario always leads to two distinct peaks. This suggests to study soft-hard correlations induced by heavy-flavor jets with those generated by light-flavor jets at RHIC and LHC in order to really disentangle medium effects from jets.
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