Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userCharged Particle Production at High Rapidity in p+p Collisions at RHIC
82
0
0.0
(
0
)
Authors
R. Debbe
Ask ChatGPT about the research
No Arabic abstract
This report describes the recent analysis of identified charged particle production at high rapidity performed on data collected from p+p collisions at RHIC (sqrt{s}=200 GeV). The extracted invariant cross-sections compare well to NLO pQCD calculations. However, a puzzling high yield of protons at high rapidity and p_T has been found.
rate research
Read More
The production of $W^{pm}$ bosons in longitudinally polarized $vec{p}+vec{p}$ collisions at RHIC provides a new means of studying the spin-flavor asymmetries of the proton sea quark distributions. Details of the $W^{pm}$ event selection in the $e^{pm}$ decay channel at mid-rapidity are presented, along with preliminary results for the production cross section and parity-violating single-spin asymmetry, $A_L$, from the STAR Collaborations 2009 data at $sqrt{s}=500$ GeV.
Particle production sensitive to non-factorizable and non-perturbative processes that contribute to the underlying event associated with a high transverse momentum ($p_{T}$) jet in proton+proton collisions at $sqrt{s}$=200 GeV is studied with the STAR detector. Each event is divided into three regions based on the azimuthal angle with respect to the highest-$p_{T}$ jet direction: in the leading jet direction (Toward), opposite to the leading jet (Away), and perpendicular to the leading jet (Transverse). In the Transverse region, the average charged particle density is found to be between 0.4 and 0.6 and the mean transverse momentum, $langle p_{T}rangle$, between 0.5-0.7 GeV/$c$ for particles with $p_{T}$$>$0.2 GeV/$c$ at mid-pseudorapidity ($|eta|$$<$1) and jet $p_{T}$$>$15 GeV/$c$. Both average particle density and $langle p_{T}rangle$ depend weakly on the leading jet $p_{T}$. Closer inspection of the Transverse region hints that contributions to the underlying event from initial- and final-state radiation are significantly smaller in these collisions than at the higher energies, up to 13 TeV, recorded at the LHC. Underlying event measurements associated with a high-$p_{T}$ jet will contribute to our understanding of QCD processes at hard and soft scales at RHIC energies, as well as provide constraints to modeling of underlying event dynamics.
The preliminary results of J/psi spectra at high transverse momentum (5<p_T<14 GeV/c) in p+p and Cu+Cu collisions at s_NN = 200 GeV are reported. The nuclear modification factor is measured to be 0.9+/-0.2 at p_T>5 GeV/c. The correlations between J/psi and charged hadrons are also studied in p+p collisions to understand the J/psi production mechanism at high p_T.
We present strange particle spectra and yields measured at mid-rapidity in $sqrt{text{s}}=200$ GeV proton-proton ($p+p$) collisions at RHIC. We find that the previously observed universal transverse mass ($mathrm{m_{T}}equivsqrt{mathrm{p_{T}}^{2}+mathrm{m}^{2}}$) scaling of hadron production in $p+p$ collisions seems to break down at higher mt and that there is a difference in the shape of the mt spectrum between baryons and mesons. We observe mid-rapidity anti-baryon to baryon ratios near unity for $Lambda$ and $Xi$ baryons and no dependence of the ratio on transverse momentum, indicating that our data do not yet reach the quark-jet dominated region. We show the dependence of the mean transverse momentum (mpt) on measured charged particle multiplicity and on particle mass and infer that these trends are consistent with gluon-jet dominated particle production. The data are compared to previous measurements from CERN-SPS, ISR and FNAL experiments and to Leading Order (LO) and Next to Leading order (NLO) string fragmentation model predictions. We infer from these comparisons that the spectral shapes and particle yields from $p+p$ collisions at RHIC energies have large contributions from gluon jets rather than quark jets.
We report on mid-rapidity mass spectrum of di-electrons and cross sections of pseudoscalar and vector mesons via $e^{+}e^{-}$ decays, from $sqrt{s} = 200$ GeV $p+p$ collisions, measured by the large acceptance experiment STAR at RHIC. The ratio of the di-electron continuum to the combinatorial background is larger than 10% over the entire mass range. Simulations of di-electrons from light-meson decays and heavy-flavor decays (charmonium and open charm correlation) are found to describe the data. The extracted $omegarightarrow e^{+}e^{-}$ invariant yields are consistent with previous measurements. The mid-rapidity yields ($dN/dy$) of $phi$ and $J/psi$ are extracted through their di-electron decay channels and are consistent with the previous measurements of $phirightarrow K^{+}K^{-}$ and $J/psirightarrow e^{+}e^{-}$. Our results suggest a new upper limit of the branching ratio of the $eta rightarrow e^{+}e^{-}$ of $1.7times10^{-5}$ at 90% confidence level.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
