共查询到20条相似文献,搜索用时 31 毫秒
1.
Elena Bruna 《The European Physical Journal C - Particles and Fields》2009,62(1):133-137
The measurement of jet fragmentation functions in p+p collisions at 200 GeV is of great interest because it provides a baseline
to study jet quenching in heavy-ion collisions. It is expected that jet quenching in nuclear matter modifies the jet energy
and multiplicity distributions, as well as the jet hadrochemical composition. Therefore, a systematic study of the fragmentation
functions for charged hadrons and identified particles is a goal both in p+p and Au+Au collisions at RHIC. Studying fragmentation
functions for identified particles is interesting in p+p by itself because it provides a test of NLO calculations at RHIC
energies. We present a systematic comparison of jet energy spectra and fragment distributions using different jet-finding
algorithms in p+p collisions in STAR. Fragmentation functions of charged and neutral strange particles are also reported for
different jet energies. 相似文献
2.
Péter Lévai 《Acta Physica Hungarica A》2004,19(3-4):277-280
We study, in a pQCD calculation augmented by nuclear effects, the jet energy loss needed to reproduce the measured π 0 spectra in Au+Au collisions at large p T , measured by PHENIX at RHIC at $\sqrt s = 200$ AGeV. Averaged energy loss obtained in the GLV formalism is applied in our recent calculation based on NLO pQCD (including shadowing and multiscattering). The method of jet tomography is capable to measure the opacity of the produced hot dense matter at RHIC energy in heavy ion collisions. 相似文献
3.
4.
5.
A study of Mach shocks generated by fast partonic jets propagating through the quark-gluon plasma(QGP)is reviewed briefly.We predict a significant deformation of Mach shocks in central Au Au collisions at RHIC and LHC energies compared to those created by a jet propagation through a static medium. Moreover,a new hydrodynamical study of jet energy loss is presented. 相似文献
6.
Sevil Salur 《The European Physical Journal C - Particles and Fields》2009,62(1):119-125
Jets can be used to probe the physical properties of the high energy density matter created in collisions at the Relativistic
Heavy Ion Collider (RHIC). Measurements of strong suppression of inclusive hadron distributions and di-hadron correlations
at high p
T
have already provided evidence for partonic energy loss. However, these measurements suffer from well-known geometric biases
due to the competition of energy loss and fragmentation. These biases can be avoided if the jets are reconstructed independently
of their fragmentation details—quenched or unquenched. In this paper, we discuss modern jet reconstruction algorithms (cone
and sequential recombination) and their corresponding background subtraction techniques required by the high multiplicities
of heavy ion collisions. We review recent results from the STAR experiment at RHIC on direct jet reconstruction in central
Au+Au collisions at
GeV. 相似文献
7.
Arsene I Bearden IG Beavis D Besliu C Budick B Bøggild H Chasman C Christensen CH Christiansen P Cibor J Debbe R Enger E Gaardhøje JJ Germinario M Hagel K Hansen O Holm A Ito H Jipa A Jundt F Jørdre JI Jørgensen CE Karabowicz R Kim EJ Kozik T Larsen TM Lee JH Lee YK Lindal S Lystad G Løvhøiden G Majka Z Makeev A McBreen B Mikelsen M Murray M Natowitz J Neumann B Nielsen BS Norris J Ouerdane D Płaneta R Rami F Ristea C Ristea O Röhrich D Samset BH Sandberg D Sanders SJ Scheetz RA Staszel P 《Physical review letters》2003,91(7):072305
We present spectra of charged hadrons from Au+Au and d+Au collisions at sqrt[s(NN)]=200 GeV measured with the BRAHMS experiment at RHIC. The spectra for different collision centralities are compared to spectra from p+(-)p collisions at the same energy scaled by the number of binary collisions. The resulting ratios (nuclear modification factors) for central Au+Au collisions at eta=0 and eta=2.2 evidence a strong suppression in the high p(T) region (>2 GeV/c). In contrast, the d+Au nuclear modification factor (at eta=0) exhibits an enhancement of the high p(T) yields. These measurements indicate a high energy loss of the high p(T) particles in the medium created in the central Au+Au collisions. The lack of suppression in d+Au collisions makes it unlikely that initial state effects can explain the suppression in the central Au+Au collisions. 相似文献
8.
We present Φ meson production in Cu+Cu and Au+Au collisions measured by the STAR experiment at RHIC.The hadronic decay mode Φ→K~+K~- is used in the analysis.The yields for Φ meson in Cu+Cu and Au+Au collisions at a given beam energy are scaled by the number of participant.The N_(part) normalized Φ meson yields in heavy ion collisions over those from p+p collisions are larger than 1 and increase with collision energy.These results suggest that the source of enhancement of strange hadrons is related to the formation of a dense medium in high energy heavy ion collisions and can not be only due to canonical suppression of their production in smaller systems.We also present STAR results on the Φ meson elliptic flow υ_2 from 2~(1/SNN)=200 GeV Cu+Cu at RHIC.The elliptic flow in Cu+Cu system that has the similar relative magnitude and qualitative features as that in Au+Au system.The observations imply the hot and dense matter with partonic collectivity has been formed in heavy ion collisions at RHIC.However,eccentrality normalized υ_2,υ_2/(n_qε_(part)) is lower for Cu+Cu than for Au+Au collisions at 200 GeV.So this might indicate thermalization has not been reached in 200 GeV Cu+Cu collisions. 相似文献
9.
10.
《Physical review letters》2007,98(19):192301
The STAR collaboration at the BNL Relativistic Heavy-Ion Collider (RHIC) reports measurements of the inclusive yield of nonphotonic electrons, which arise dominantly from semileptonic decays of heavy flavor mesons, over a broad range of transverse momenta (1.2
相似文献
11.
Important goals of BNL RHIC and CERN LHC experiments with ion beams include the creation and study of new forms of matter, such as the quark gluon plasma. Heavy quark production and attenuation provide unique tomographic probes of that matter. We predict the suppression pattern of open charm and beauty in Au+Au collisions at RHIC and LHC energies based on the DGLV formalism of radiative energy loss. A cancellation between effects due to the sqrt[s] energy dependence of the high p(T) slope and heavy quark energy loss is predicted to lead to surprising similarity of heavy quark suppression at RHIC and LHC. 相似文献
12.
Xin Dong 《The European Physical Journal C - Particles and Fields》2009,61(4):659-664
I report the most recent measurements on open heavy flavor production at RHIC on behalf of the STAR collaboration. The total
charm production cross section in midrapidity at RHIC energy is found to approximately scale by number of binary collisions
in d + Au, Cu + Cu and Au + Au collisions. The nuclear modification factor of non-photonic electrons is strongly suppressed in
central Au + Au collisions, suggesting substantial heavy quark energy loss at RHIC. The bottom decay contribution to non-photonic
electrons was studied via the e–h and e–D
0 azimuthal angular correlations. The bottom contribution is found to be important at p
T
>5 GeV/c, and is consistent with the FONLL calculation within uncertainties. Charm production through gluon jet splitting was measured
by studying the D
*± contents in the fully reconstructed jets in p+p collisions. This rate is consistent with pQCD evaluation of gluon splitting into a pair of charm quarks and subsequent hadronization. 相似文献
13.
M. Calderón de la Barca Sánchez 《The European Physical Journal C - Particles and Fields》2005,43(1-4):187-192
Charmed hadrons are interesting observables in heavy ion collisions. They are becoming more accessible to experimental scrutiny
at RHIC energies due to the increased production cross-section of charm with the larger centre-of-mass energy available at
RHIC compared to SPS. One source of interest in charm production is due to the fact that gluon fusion dominates the charm
production cross-section at high energy. Hence, a measurement of charm hadrons is directly sensitive to the gluon distributions
of the colliding particles. In addition, any measurement of production at RHIC, and more importantly any observed suppression,
must be compared to the overall production of pairs. A systematic study of charmed hadrons in all collision systems available
at RHIC is therefore an invaluable experimental tool in the characterization of the matter produced at RHIC. In particular,
d + Au collisions are a necessary step for the comparison of any possible modification of charm production in Au + Au collisions.
We present preliminary results on D meson production from d + Au collisions in STAR at = 200 .
Arrival of the final proofs: 26 July 2005
PACS:
13.20.Fc, 13.25.Ft, 25.75.-q, 24.85. + p 相似文献
14.
Brooke Haag 《Indian Journal of Physics》2011,85(1):123-127
Di-hadron correlation measurements have been used to probe di-jet production in heavy ion collisions at RHIC. A strong suppression
of the away-side high-p
T
yield in these measurements is direct evidence that high-p
T
partons lose energy as they traverse the strongly interacting medium. However, since the momentum of the trigger particle
is not a good measure of the jet energy, azimuthal di-hadron correlations have limited sensitivity to the shape of the fragmentation
function. We explore the possibility to better constrain the initial parton energy by using clusters of multiple high-p
T
hadrons in a narrow cone as the ‘trigger particle’ in the azimuthal correlation analysis. We present first results from this
analysis of multi-hadron triggered correlated yields in Au+Au collisions at $
\sqrt {s_{NN} }
$
\sqrt {s_{NN} }
= 200 GeV from STAR. The results are compared with measurements in d + Au collisions and Pythia calculations, and the implications for energy loss and jet fragmentation are discussed. 相似文献
15.
S. Bathe 《The European Physical Journal C - Particles and Fields》2007,49(1):225-229
Results from the PHENIX experiment at RHIC on direct photon production in p+p, d+Au, and Au+Au collisions at =200 GeV are presented. In p+p collisions, direct photon production at high pT behaves as expected from perturbative QCD calculations. The p+p measurement serves as a baseline for direct photon production
in Au+Au collisions. In d+Au collisions, no effects of cold nuclear matter are found within the large uncertainty of the measurement.
In Au+Au collisions, the production of high pT direct photons scales as expected for particle production in hard scatterings. This supports jet quenching models, which
attribute the suppression of high pT hadrons to the energy loss of fast partons in the medium produced in the collision. Low pT direct photons, measured via e+e- pairs with small invariant mass, are possibly related to the production of thermal direct photons. 相似文献
16.
C. Merino C. Pajares Yu. M. Shabelski 《The European Physical Journal C - Particles and Fields》2009,59(3):691-703
In the framework of the quark–gluon string model we calculate the inclusive spectra of secondaries produced in d+Au collisions at intermediate (CERN SPS) and at much higher (RHIC) energies. The results of numerical calculations at intermediate
energies are in reasonable agreement with the data. At RHIC energies numerically large inelastic screening corrections (percolation
effects) should be accounted for in the calculations. We extract these effects from the existing experimental data of RHIC
on minimum-bias and central d+Au collisions. The predictions for p+Au interactions at LHC energy are also given. 相似文献
17.
18.
N. Borghini 《The European Physical Journal C - Particles and Fields》2007,49(1):327-331
The explanation of the suppression of high-pT hadron yields at RHIC in terms of jet-quenching implies that the multiplicity distributions of particles inside a jet and
jet-like particle correlations differ strongly in nucleus–nucleus collisions at RHIC or at the LHC from those observed at
e+e- or hadron colliders. We present a framework for describing the medium-induced modification, which has a direct interpretation
in terms of a probabilistic medium-modified parton cascade, and which treats leading and subleading partons on an equal footing.
We show that our approach can account for the strong suppression of single inclusive hadron spectra measured in Au–Au collisions
at RHIC, and that this implies a characteristic distortion of the single inclusive distribution of soft partons inside the
jet. We determine, as a function of the jet energy, to what extent the soft fragments within a jet can be measured above some
momentum cut.
PACS 12.38.Mh; 25.75.-q 相似文献
19.
Bedangadas Mohanty 《Pramana》2006,67(5):927-935
We present some of the important experimental results from nucleus-nucleus collision studies carried out by the STAR experiment
at Relativistic Heavy Ion Collider (RHIC). The results suggests that central Au+Au collisions at RHIC has produced a dense
and rapidly thermalizing matter with initial energy densities above the critical values predicted by lattice QCD for establishment
of a quark-gluon plasma (QGP). 相似文献
20.
Back BB Baker MD Barton DS Betts RR Bindel R Budzanowski A Busza W Carroll A Decowski MP Garcia E George N Gulbrandsen K Gushue S Halliwell C Hamblen J Henderson C Hofman D Hollis RS Hołyński R Holzman B Iordanova A Johnson E Kane J Katzy J Khan N Kucewicz W Kulinich P Kuo CM Lin WT Manly S McLeod D Michałowski J Mignerey A Nouicer R Olszewski A Pak R Park IC Pernegger H Reed C Remsberg LP Reuter M Roland C Roland G Rosenberg L Sagerer J Sarin P Sawicki P Skulski W Steadman SG Steinberg P 《Physical review letters》2002,89(22):222301
This paper describes the measurement of collective flow for charged particles in Au+Au collisions at sqrt[s(NN)]=130 GeV using the PHOBOS detector at the Relativistic Heavy Ion Collider (RHIC). The measured azimuthal hit anisotropy is presented over a wide range of pseudorapidity (-5.0相似文献