Quarkonium Results in PbPb Collisions at CMS

We summarize the results from the study of charmonium and bottomonium via the dimuon decay channel in PbPb collisions with the CMS experiment. We discuss the observation of sequential suppression of the Upsilon states. We present preliminary results of prompt J/psi and psi' production, as well as of non-prompt J/psis coming from the weak decay of b-quarks. This latter measurement is sensitive to b-quark energy loss. We discuss the results and compare to model predictions.Comment: 8 pages, 4 figures. Proceedings of 29th Winter Workshop on Nuclear Dynamic

STAR Results on High Transverse Momentum, Heavy Flavor and Electromagnetic Probes

We summarize here recent results from the STAR collaboration focusing on processes involving large momentum transfers. Measurements of angular correlations of di-hadrons are explored in both the pseudorapidity (eta) and azimuthal (phi) projections. In central Au+Au, an elongated structure is found in the eta projection which persists up to the highest measured pT. After quantifying the particle yield in this structure and subtracting it from the near-side yield, we observe that the remainder exhibits a behavior strikingly similar to that of the near-side yield in d+Au. For heavy flavor production, using electron-hadron correlations in p+p collisions, we obtain an estimate of the b-quark contribution to the non-photonic electrons in the pT region 3-6 GeV/c, and find it consistent with FONLL calculations. Together with the observed suppression of non-photonic electrons in Au+Au, this strongly suggests suppression of b-quark production in Au+Au collisions. We discuss results on the mid-rapidity Upsilon cross-section in p+p collisions. Finally, we present a proof-of-principle measurement of photon-hadron correlations in p+p collisions, paving the way for the tomographic study of the matter produced in central Au+Au via gamma-jet measurements.Comment: 8 pages, 4 figures. Proceedings of "Quark Matter 2006", 19th International Conference on Ultra-Relativistic Nucleus-Nucleus Collision

Composición nutricional de nuevas variedades de cacahuate (Arachis Hypogaea L.)

Six peanut (Arachis hypogaea L.) cultivars (Col-24-Gro, Col-61-Gto, VA-81-B, Ranferi Díaz, NC-2 and Florunner) were studied for agricultural yield, chemical composition (protein, fat, carbohydrates, fiber and ash), amino acid profile, digestibility, fatty acid profile, tocopherol and sterol contents. Results indicated that Ranferi Díaz and Col-61-Gto presented the highest yield (6.3 Ton/ha). Protein content was from 23.5 to 26.6% and fat content ranged from 49.8-53.4%. Mean digestibility was 86%. Lysine and threonine levels in all cultivars were sufficient to meet human requirements. Total saturated fatty acids ranged from 15-18%. The oleic/linoleic ratio was estimated 1.3-1.4. Tocopherol levels varied from 390 to 706 ppm. The highest tocopherol levels corresponded to the cultivars with the lowest yield. The alpha tocopherol content was estimated at 90-150 ppm, while gamma tocopherol was 270-570 ppm.The main sterol present was βsitosterol (approx. 65%). Ranferi Diaz variety presented the highest agronomic yield and the highest protein content but low oleic acid, low sterols and low total tocopherols. The differences among cultivars suggest differences in their applications.Se estudio el rendimiento agrícola y composición química (proteína, grasa, carbohidratos, fibra y cenizas), perfil de amino ácidos, digestibilidad, perfil de ácidos grasos, contenido de tocoferol y de esteroles de seis variedades de cacahuate (Arachis hypogaea L.) Col-24-Gro, Col-61-Gto, VA-81B, Ranferi Díaz, NC-2 y Florunner. Los resultados mostraron que el mayor rendimiento se logró en las variedades Ranferi Díaz y Col-61-Gto (6.3 Ton/ha). El contenido de proteína fue de 23.5 a 26.6% y el contenido de grasa en un intervalo de 49.8 a 53.4%. La digestibilidad promedio de las seis variedades fue de 86%. El contenido de lisina y treonina en la proteína de todas las variedades fue suficiente para satisfacer los requerimientos del humano. La composición del aceite de las diferentes variedades de cacahuate se caracterizó por contener de 15-18% de ácidos grasos saturados. La relación oleico/linoleico fue de 1.3-1.4. El contenido de tocoferoles totales fue entre 390 a 706 ppm. El mayor contenido de tocoferol correspondió a las variedades con los rendimientos más bajos. Con respecto al contenido de alfa tocoferol se encontró entre 90-150 ppm y el gamma tocoferol fue entre 270570 ppm. El contenido de beta-sitosterol fue similar en las seis variedades (aprox. 65%). La variedad Ranferi Diaz presentó el más alto rendimiento agronómico y el más alto contenido de proteína. Sin embargo, esta variedad presento el más bajo contenido de ácido oleico, bajo contenido de esteroles y bajo contenido de tocoferoles totales. Estas diferencias entre las variedades de cacahuate sugieren que cada una de ellas deberá tener diferente uso como alimento

The STAR Time Projection Chamber: A Unique Tool for Studying High Multiplicity Events at RHIC

The STAR Time Projection Chamber (TPC) is used to record collisions at the Relativistic Heavy Ion Collider (RHIC). The TPC is the central element in a suite of detectors that surrounds the interaction vertex. The TPC provides complete coverage around the beam-line, and provides complete tracking for charged particles within +- 1.8 units of pseudo-rapidity of the center-of-mass frame. Charged particles with momenta greater than 100 MeV/c are recorded. Multiplicities in excess of 3,000 tracks per event are routinely reconstructed in the software. The TPC measures 4 m in diameter by 4.2 m long, making it the largest TPC in the world.Comment: 28 pages, 11 figure

Centrality and Transverse Momentum Dependence of Elliptic Flow of Multistrange Hadrons and \u3cem\u3eϕ\u3c/em\u3e Meson in Au + Au Collisions at √\u3cem\u3e\u3csup\u3es\u3c/sup\u3e\u3csub\u3eNN\u3c/sub\u3e\u3c/em\u3e = 200 GeV

We present high precision measurements of elliptic flow near midrapidity (|y| \u3c 1.0) for multistrange hadrons and ϕ meson as a function of centrality and transverse momentum in Au + Au collisions at center of mass energy √sNN = 200  GeV. We observe that the transverse momentum dependence of ϕ and Ω υ2 is similar to that of π and p, respectively, which may indicate that the heavier strange quark flows as strongly as the lighter up and down quarks. This observation constitutes a clear piece of evidence for the development of partonic collectivity in heavy-ion collisions at the top RHIC energy. Number of constituent quark scaling is found to hold within statistical uncertainty for both 0%–30% and 30%–80% collision centrality. There is an indication of the breakdown of previously observed mass ordering between ϕ and proton υ2 at low transverse momentum in the 0%–30% centrality range, possibly indicating late hadronic interactions affecting the proton υ2

Measurement of the Transverse Single-Spin Asymmetry in \u3cem\u3ep\u3c/em\u3e\u3csup\u3e↑\u3c/sup\u3e+\u3cem\u3ep\u3c/em\u3e→\u3cem\u3eW\u3c/em\u3e\u3csup\u3e±\u3c/sup\u3e/\u3cem\u3eZ\u3c/em\u3e\u3csup\u3e0\u3c/sup\u3e at RHIC

We present the measurement of the transverse single-spin asymmetry of weak boson production in transversely polarized proton-proton collisions at √s = 500  GeV by the STAR experiment at RHIC. The measured observable is sensitive to the Sivers function, one of the transverse-momentum-dependent parton distribution functions, which is predicted to have the opposite sign in proton-proton collisions from that observed in deep inelastic lepton-proton scattering. These data provide the first experimental investigation of the nonuniversality of the Sivers function, fundamental to our understanding of QCD

Measurement of Elliptic Flow of Light Nuclei at √\u3cem\u3e\u3csup\u3eS\u3c/sup\u3e\u3csub\u3eNN\u3c/sub\u3e\u3c/em\u3e = 200, 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV at the BNL Relativistic Heavy Ion Collider

We present measurements of second-order azimuthal anisotropy (υ2) at midrapidity (|y| \u3c 1.0) for light nuclei d, t, 3He (for ⎷sNN = 200 GeV) in the STAR (Solenoidal Tracker at RHIC) experiment. The υ2 for these light nuclei produced in heavy-ion collisions is compared with those for p and p¯. We observe mass ordering in nuclei υ2 (pT) at low transverse momenta (pT \u3c 2.0 GeV/c). We also find a centrality dependence of υ2 for d and d¯. The magnitude of υ2 for t and 3He agree within statistical errors. Light-nuclei υ2 are compared with predictions from a blast-wave model. Atomic mass number (A) scaling of light-nuclei υ2 (pT) seems to hold for pT/A \u3c 1.5 GeV/c. Results on light-nuclei υ2 from a transport-plus-coalescence model are consistent with the experimental measurements

Centrality Dependence of Identified Particle Elliptic Flow in Relativistic Heavy Ion Collisions at √\u3cem\u3e\u3csup\u3es\u3c/sup\u3e\u3csub\u3eNN\u3c/sub\u3e\u3c/em\u3e = 7.7–62.4 GeV

Elliptic flow (υ2) values for identified particles at midrapidity in Au + Au collisions measured by the STAR experiment in the Beam Energy Scan at the Relativistic Heavy Ion Collider at √sNN = 7.7– 62.4 GeV are presented for three centrality classes. The centrality dependence and the data at √sNN = 14.5 GeV are new. Except at the lowest beam energies, we observe a similar relative υ2 baryon-meson splitting for all centrality classes which is in agreement within 15% with the number-of-constituent quark scaling. The larger υ2 for most particles relative to antiparticles, already observed for minimum bias collisions, shows a clear centrality dependence, with the largest difference for the most central collisions. Also, the results are compared with a multiphase transport (AMPT) model and fit with a blast wave model

\u3cem\u3eJ/ψ\u3c/em\u3e Production at Low Transverse Momentum in \u3cem\u3ep\u3c/em\u3e + \u3cem\u3ep\u3c/em\u3e and \u3cem\u3ed\u3c/em\u3e + Au Collisions at √\u3cem\u3e\u3csup\u3es\u3c/sup\u3e\u3csub\u3eNN\u3c/sub\u3e\u3c/em\u3e = 200 GeV

We report on the measurement of J/ψ production in the dielectron channel at midrapidity (|y| \u3c 1) in p + p and d + Au collisions at √sNN = 200 GeV from the STAR experiment at the Relativistic Heavy Ion Collider. The transverse momentum pTspectra in p + p for pT \u3c 4 GeV/c and d + Au collisions for pT \u3c 3 GeV/c are presented. These measurements extend the STAR coverage for J/ψ production in p + p collisions to low pT. The ⟨p2T⟩ from the measured J/ψ invariant cross section in p + p and d + Au collisions are evaluated and compared to similar measurements at other collision energies. The nuclear modification factor for J/ψ is extracted as a function of pT and collision centrality in d + Au and compared to model calculations using the modified nuclear parton distribution function and a final-state J/ψ nuclear absorption cross section

Probing Parton Dynamics of QCD Matter with Ω and \u3cem\u3eϕ\u3c/em\u3e Production

We present measurements of Ω and ϕ production at midrapidity from Au+Au collisions at nucleon-nucleon center-of-mass energies √sNN = 7.7, 11.5, 19.6, 27, and 39 GeV by the STAR experiment at the BNL Relativistic Heavy Ion Collider (RHIC). Motivated by the coalescence formation mechanism for these strange hadrons, we study the ratios of N (Ω- + Ω−+) / [2N(ϕ)]. These ratios as a function of transverse momentum pT fall on a consistent trend at high collision energies, but start to show deviations in peripheral collisions at √sNN = 19.6, 27, and 39 GeV, and in central collisions at 11.5 GeV in the intermediate pT region of 2.4−3.6 GeV/c. We further evaluate empirically the strange quark pT distributions at hadronization by studying the Ω/ϕ ratios scaled by the number of constituent quarks (NCQ). The NCQ-scaled Ω/ϕ ratios show a suppression of strange quark production in central collisions at 11.5 GeV compared to √sNN ≥ 19.6 GeV. The shapes of the presumably thermal strange quark distributions in 0–60% most central collisions at 7.7 GeV show significant deviations from those in 0–10% most central collisions at higher energies. These features suggest that there is likely a change of the underlying strange quark dynamics in the transition from quark matter to hadronic matter at collision energies below 19.6 GeV