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Register a new userRecent Heavy-Flavor results at STAR
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Zhangbu Xu
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We present the recent results on non-photonic electron (NPE) yields from RHIC run8 p+p collisions. The $e/pi$ ratio as a function of $p_T$ in run8 with a factor of 10 reduction of the inner detector material at STAR is found to be consistent with those results from run3 taking into account the NPE from charm leptonic decay and the difference of photonic electron yield from photon conversion in detector material. Jpsi spectra in pp and cucu collisions at sNN = 200 GeV with high sampled luminosity Jpsi spectrum at high-pT follows $x_T$ scaling, but the scaling is violated at low pT. $J/psi$-hadron correlations in pp collisions are studied to understand the Jpsi production mechanism at high $p_T$. We observed an absence of charged hadrons accompanying Jpsi on the near-side, in contrast to the strong correlation peak in the di-hadron correlations. This constrains the $B$-meson contribution and jet fragmentation to inclusive Jpsi to be ${}^{<}_{sim}17%$. Yields in minimum-bias cucu collisions are consistent with those in pp collisions scaled by the underlying binary nucleon-nucleon collisions in the measured pT range. Other measurements and future projects related to heavy-flavors are discussed.
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In these proceedings, we report on the production of various open heavy-flavor hadrons and quarkonia in Au+Au collisions at sNN = 200GeV from the STAR experiment.
The CDF and D0 experiments at the Tevatron ppbar collider have pioneered and established the role of flavor physics in hadron collisions. A broad program is now at its full maturity. We report on three new results sensitive to physics beyond the standard model, obtained using the whole CDF dataset: a measurement of the difference of CP asymmetries in $K^+K^-$ and $pi^+pi^-$ decays of $D^0$ mesons, new bounds on the $B^0_s$ mixing phase and on the decay width difference of $B^0_s$ mass-eigenstates, and an update of the summer 2011 search for $B^0_(s)$ mesons decaying into pairs of muons. Finally, the D0 confirmation of the observation of a new hadron, the $chi_b(3P)$ state, is briefly mentioned.
Results are presented from the ATLAS collaboration from the 2010 LHC heavy ion run, during which nearly 10 inverse microbarns of luminosity were delivered. Soft physics results include charged particle multiplicities and collective flow. The charged particle multiplicity, which tracks initial state entropy production, increases by a factor of two relative to the top RHIC energy, with a centrality dependence very similar to that already measured at RHIC. Measurements of elliptic flow out to large transverse momentum also show similar results to what was measured at RHIC, but no significant pseudorapidity dependence. Extensions of these measurements to higher harmonics have also been made, and can be used to explain structures in the two-particle correlation functions that had long been attributed to jet-medium interactions. New hard probe measurements include single muons, jets and high $p_T$ hadrons. Single muons at high momentum are used to extract the yield of $W^{pm}$ bosons and are found to be consistent within statistical uncertainties with binary collision scaling. Conversely, jets are found to be suppressed in central events by a factor of two relative to peripheral events, with no significant dependence on the jet energy. Fragmentation functions are also found to be the same in central and peripheral events. Finally, charged hadrons have been measured out to 30 GeV, and their centrality dependence relative to peripheral events is similar to that found for jets.
We present selected recent results of multi-hadron correlation measurements in azimuth and pseudorapidity at intermediate and high pt{} in Au+Au collisions at $sqrt{s_{NN}}=200$ GeV, from the STAR experiment at RHIC. At intermediate pt, measurements are presented that attempt to determine the origin of the associated near-side (small dphi) yield at large pseudo-rapidity difference deta{} that is found to be present in heavy ion collisions. In addition, results are reported on new multi-hadron correlation measures at high-pt{} that use di-hadron triggers and multi-hadron cluster triggers with the goal to constrain the underlying jet kinematics better than in the existing measurements of inclusive spectra and di-hadron correlations.
Flow measurements of multi-strange baryons from Au + Au collisions at RHIC energies demonstrate that collectivity develops before hadronization, among partons. To pin down the partonic EOS of matter produced at RHIC, the status of thermalization in such collisions has to be addressed. We propose to measure collective flow of heavy-flavor quarks, e.g. charm quarks, as an indicator of thermalization of light flavors ($u,d,s$). The completion of the time of flight barrel and the proposed upgrade with a $mu$Vertex detector for heavy-flavor identification in STAR are well suited for achieving these goals.
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