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F. Alessandria,
E. Andreotti,
R. Ardito,
C. Arnaboldi,
F. A. III,
M. Balata,
I. Bandac,
T. Banks,
G. Bari,
J. Beeman, [......],
B. Wang,
H. Wang, C. Whitten,
T. Wise,
A. Woodcraft,
N. Xu,
L. Zanotti,
C. Zarra,
B. Zhu,
S. Zucchelli
[show abstract]
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ABSTRACT: The CUORE Crystal Validation Runs (CCVRs) have been carried out since the end of 2008 at the Gran Sasso National Laboratories, in order to test the performance and the radiopurity of the TeO2 crystals produced at SICCAS (Shanghai Institute of Ceramics, Chinese Academy of Sciences) for the CUORE experiment. In this work the results of the first 5 validation runs are presented. Results have been obtained for bulk contaminations and surface contaminations from several nuclides. An extrapolation to the CUORE background has been performed.
Astroparticle Physics 03/2012; 35(12):839–849. · 3.22 Impact Factor
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G Agakishiev,
M M Aggarwal,
Z Ahammed,
A V Alakhverdyants,
I Alekseev,
J Alford,
B D Anderson,
C D Anson,
D Arkhipkin,
G S Averichev, [......],
W M Zhang,
X P Zhang,
Y Zhang,
Z P Zhang,
F Zhao,
J Zhao,
C Zhong,
X Zhu,
Y H Zhu,
Y Zoulkarneeva
[show abstract]
[hide abstract]
ABSTRACT: We report new STAR measurements of midrapidity yields for the Λ, Λ[over ¯], K(S)(0), Ξ(-), Ξ[over ¯](+), Ω(-), Ω[over ¯](+) particles in Cu+Cu collisions at √S(NN)==200 GeV, and midrapidity yields for the Λ, Λ[over ¯], K(S)(0) particles in Au+Au at √S(NN)==200 GeV. We show that, at a given number of participating nucleons, the production of strange hadrons is higher in Cu+Cu collisions than in Au+Au collisions at the same center-of-mass energy. We find that aspects of the enhancement factors for all particles can be described by a parametrization based on the fraction of participants that undergo multiple collisions.
Physical Review Letters 02/2012; 108(7):072301. · 7.37 Impact Factor
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G Agakishiev,
M M Aggarwal,
Z Ahammed,
A V Alakhverdyants,
I Alekseev,
J Alford,
B D Anderson,
C D Anson,
D Arkhipkin,
G S Averichev, [......],
W M Zhang,
X P Zhang,
Y Zhang,
Z P Zhang,
F Zhao,
J Zhao,
C Zhong,
X Zhu,
Y H Zhu,
Y Zoulkarneeva
[show abstract]
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ABSTRACT: We report transverse momentum (p(T)≤15 GeV/c) spectra of π(±), K(±), p, p[over ¯], K(S)(0), and ρ(0) at midrapidity in p+p and Au+Au collisions at √S(NN)=200 GeV. Perturbative QCD calculations are consistent with π(±) spectra in p+p collisions but do not reproduce K and p(p[over ¯]) spectra. The observed decreasing antiparticle-to-particle ratios with increasing p(T) provide experimental evidence for varying quark and gluon jet contributions to high-p(T) hadron yields. The relative hadron abundances in Au+Au at p(T)≳8 GeV/c are measured to be similar to the p+p results, despite the expected Casimir effect for parton energy loss.
Physical Review Letters 02/2012; 108(7):072302. · 7.37 Impact Factor
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M M Aggarwal,
Z Ahammed,
A V Alakhverdyants,
I Alekseev,
J Alford,
B D Anderson,
C D Anson,
D Arkhipkin,
G S Averichev,
J Balewski, [......],
X P Zhang,
Y Zhang,
Z P Zhang,
J Zhao,
C Zhong,
W Zhou,
X Zhu,
Y H Zhu,
R Zoulkarneev,
Y Zoulkarneeva
[show abstract]
[hide abstract]
ABSTRACT: We report the first measurement of the parity-violating single-spin asymmetries for midrapidity decay positrons and electrons from W+ and W- boson production in longitudinally polarized proton-proton collisions at sqrt[s] = 500 GeV by the STAR experiment at RHIC. The measured asymmetries, A(L)(W+) = -0.27 ± 0.10(stat.) ± 0.02(syst.) ± 0.03(norm.) and A(L)(W-) = 0.14 ± 0.19(stat.) ± 0.02(syst.) ± 0.01(norm.), are consistent with theory predictions, which are large and of opposite sign. These predictions are based on polarized quark and antiquark distribution functions constrained by polarized deep-inelastic scattering measurements.
Physical Review Letters 02/2011; 106(6):062002. · 7.37 Impact Factor
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M M Aggarwal,
Z Ahammed,
A V Alakhverdyants,
I Alekseev,
J Alford,
B D Anderson,
Daniel Anson,
D Arkhipkin,
G S Averichev,
J Balewski, [......],
Y Zhang,
Z P Zhang,
J Zhao,
C Zhong,
J Zhou,
W Zhou,
X Zhu,
Y H Zhu,
R Zoulkarneev,
Y Zoulkarneeva
[show abstract]
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ABSTRACT: The contribution of B meson decays to nonphotonic electrons, which are mainly produced by the semileptonic decays of heavy-flavor mesons, in p + p collisions at √s=200 GeV has been measured using azimuthal correlations between nonphotonic electrons and hadrons. The extracted B decay contribution is approximately 50% at a transverse momentum of pT≥5 GeV/c. These measurements constrain the nuclear modification factor for electrons from B and D meson decays. The result indicates that B meson production in heavy ion collisions is also suppressed at high pT.
Physical Review Letters 11/2010; 105(20):202301. · 7.37 Impact Factor
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M M Aggarwal,
Z Ahammed,
A V Alakhverdyants,
I Alekseev,
J Alford,
B D Anderson,
D Arkhipkin,
G S Averichev,
J Balewski,
L S Barnby, [......],
Y Zhang,
Z P Zhang,
J Zhao,
C Zhong,
J Zhou,
W Zhou,
X Zhu,
Y H Zhu,
R Zoulkarneev,
Y Zoulkarneeva
[show abstract]
[hide abstract]
ABSTRACT: We report the first measurements of the kurtosis (κ), skewness (S), and variance (σ2) of net-proton multiplicity (Np-Np) distributions at midrapidity for Au+Au collisions at square root of s(NN)=19.6, 62.4, and 200 GeV corresponding to baryon chemical potentials (μB) between 200 and 20 MeV. Our measurements of the products κσ2 and Sσ, which can be related to theoretical calculations sensitive to baryon number susceptibilities and long-range correlations, are constant as functions of collision centrality. We compare these products with results from lattice QCD and various models without a critical point and study the square root of s(NN) dependence of κσ2. From the measurements at the three beam energies, we find no evidence for a critical point in the QCD phase diagram for μB below 200 MeV.
Physical Review Letters 07/2010; 105(2):022302. · 7.37 Impact Factor
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B I Abelev,
M M Aggarwal,
Z Ahammed,
A V Alakhverdyants,
B D Anderson,
D Arkhipkin,
G S Averichev,
J Balewski,
O Barannikova,
L S Barnby, [......],
Y Zhang,
Z P Zhang,
J Zhao,
C Zhong,
J Zhou,
W Zhou,
X Zhu,
Y-H Zhu,
R Zoulkarneev,
Y Zoulkarneeva
[show abstract]
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ABSTRACT: We report the first three-particle coincidence measurement in pseudorapidity (Δη) between a high transverse momentum (p⊥) trigger particle and two lower p⊥ associated particles within azimuth |Δϕ|<0.7 in square root of s(NN)=200 GeV d+Au and Au+Au collisions. Charge ordering properties are exploited to separate the jetlike component and the ridge (long range Δη correlation). The results indicate that the correlation of ridge particles are uniform not only with respect to the trigger particle but also between themselves event by event in our measured Δη. In addition, the production of the ridge appears to be uncorrelated to the presence of the narrow jetlike component.
Physical Review Letters 07/2010; 105(2):022301. · 7.37 Impact Factor
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B I Abelev,
M M Aggarwal,
Z Ahammed,
A V Alakhverdyants,
I Alekseev,
B D Anderson,
D Arkhipkin,
G S Averichev,
J Balewski,
L S Barnby, [......],
Y Zhang,
Z P Zhang,
J Zhao,
C Zhong,
J Zhou,
W Zhou,
X Zhu,
Y H Zhu,
R Zoulkarneev,
Y Zoulkarneeva
[show abstract]
[hide abstract]
ABSTRACT: Nuclear collisions recreate conditions in the universe microseconds after the Big Bang. Only a very small fraction of the emitted fragments are light nuclei, but these states are of fundamental interest. We report the observation of antihypertritons--comprising an antiproton, an antineutron, and an antilambda hyperon--produced by colliding gold nuclei at high energy. Our analysis yields 70 +/- 17 antihypertritons ((Lambda)(3)-H) and 157 +/- 30 hypertritons (Lambda3H). The measured yields of Lambda3H ((Lambda)(3)-H) and 3He (3He) are similar, suggesting an equilibrium in coordinate and momentum space populations of up, down, and strange quarks and antiquarks, unlike the pattern observed at lower collision energies. The production and properties of antinuclei, and of nuclei containing strange quarks, have implications spanning nuclear and particle physics, astrophysics, and cosmology.
Science 03/2010; 328(5974):58-62. · 31.20 Impact Factor
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B I Abelev,
M M Aggarwal,
Z Ahammed,
A V Alakhverdyants,
B D Anderson,
D Arkhipkin,
G S Averichev,
J Balewski,
O Barannikova,
L S Barnby, [......],
X P Zhang,
Y Zhang,
Z P Zhang,
Y Zhao,
C Zhong,
J Zhou,
X Zhu,
R Zoulkarneev,
Y Zoulkarneeva,
J X Zuo
[show abstract]
[hide abstract]
ABSTRACT: Parity-odd domains, corresponding to nontrivial topological solutions of the QCD vacuum, might be created during relativistic heavy-ion collisions. These domains are predicted to lead to charge separation of quarks along the system's orbital momentum axis. We investigate a three-particle azimuthal correlator which is a P even observable, but directly sensitive to the charge separation effect. We report measurements of charged hadrons near center-of-mass rapidity with this observable in Au + Au and Cu + Cu collisions at square root of s(NN) = 200 GeV using the STAR detector. A signal consistent with several expectations from the theory is detected. We discuss possible contributions from other effects that are not related to parity violation.
Physical Review Letters 12/2009; 103(25):251601. · 7.37 Impact Factor
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B. I. Abelev,
M. M. Aggarwal,
Z. Ahammed,
A. V. Alakhverdyants,
B. D. Anderson,
D. Arkhipkin,
G. S. Averichev,
J. Balewski,
O. Barannikova,
L. S. Barnby, [......],
S. Zhang,
W. M. Zhang,
X. P. Zhang,
Y. Zhang,
C. Zhong,
J. Zhou,
X. Zhu,
R. Zoulkarneev,
Y. Zoulkarneeva,
J. X. Zuo
Nuclear Physics A 10/2009; 830:969-971. · 1.54 Impact Factor
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B I Abelev,
M M Aggarwal,
Z Ahammed,
B D Anderson,
D Arkhipkin,
G S Averichev,
J Balewski,
O Barannikova,
L S Barnby,
J Baudot, [......],
W M Zhang,
X P Zhang,
Y Zhang,
Z P Zhang,
Y Zhao,
C Zhong,
J Zhou,
R Zoulkarneev,
Y Zoulkarneeva,
J X Zuo
[show abstract]
[hide abstract]
ABSTRACT: Forward-backward multiplicity correlation strengths have been measured with the STAR detector for Au + Au and p + p collisions at square root of s(NN) = 200 GeV. Strong short- and long-range correlations (LRC) are seen in central Au + Au collisions. The magnitude of these correlations decrease with decreasing centrality until only short-range correlations are observed in peripheral Au + Au collisions. Both the dual parton model (DPM) and the color glass condensate (CGC) predict the existence of the long-range correlations. In the DPM, the fluctuation in the number of elementary (parton) inelastic collisions produces the LRC. In the CGC, longitudinal color flux tubes generate the LRC. The data are in qualitative agreement with the predictions of the DPM and indicate the presence of multiple parton interactions.
Physical Review Letters 10/2009; 103(17):172301. · 7.37 Impact Factor
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B I Abelev,
M M Aggarwal,
Z Ahammed,
B D Anderson,
D Arkhipkin,
G S Averichev,
J Balewski,
O Barannikova,
L S Barnby,
J Baudot, [......],
W M Zhang,
X P Zhang,
Y Zhang,
Z P Zhang,
Y Zhao,
C Zhong,
J Zhou,
R Zoulkarneev,
Y Zoulkarneeva,
J X Zuo
[show abstract]
[hide abstract]
ABSTRACT: We report K/pi fluctuations from Au + Au collisions at sqrt[s(NN)]= 19.6, 62.4, 130, and 200 GeV using the STAR detector at the Relativistic Heavy Ion Collider. K/pi fluctuations in central collisions show little dependence on incident energy and are on the same order as those from NA49 at the Super Proton Synchrotron in central Pb + Pb collisions at sqrt[s(NN)]=12.3 and 17.3 GeV. We report results for the collision centrality dependence of K/pi fluctuations and results for charge-separated fluctuations. We observe that the K/pi fluctuations scale with the charged particle multiplicity density.
Physical Review Letters 08/2009; 103(9):092301. · 7.37 Impact Factor
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B I Abelev,
M M Aggarwal,
Z Ahammed,
B D Anderson,
D Arkhipkin,
G S Averichev,
Y Bai,
J Balewski,
O Barannikova,
L S Barnby, [......],
S Zhang,
W M Zhang,
Y Zhang,
Z P Zhang,
Y Zhao,
C Zhong,
J Zhou,
R Zoulkarneev,
Y Zoulkarneeva,
J X Zuo
[show abstract]
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ABSTRACT: In ultraperipheral relativistic heavy-ion collisions, a photon from the electromagnetic field of one nucleus can fluctuate to a quark-antiquark pair and scatter from the other nucleus, emerging as a rho{0}. The rho{0} production occurs in two well-separated (median impact parameters of 20 and 40 F for the cases considered here) nuclei, so the system forms a two-source interferometer. At low transverse momenta, the two amplitudes interfere destructively, suppressing rho{0} production. Since the rho{0} decays before the production amplitudes from the two sources can overlap, the two-pion system can only be described with an entangled nonlocal wave function, and is thus an example of the Einstein-Podolsky-Rosen paradox. We observe this suppression in 200 GeV per nucleon-pair gold-gold collisions. The interference is 87%+/-5%(stat.)+/-8%(syst.) of the expected level. This translates into a limit on decoherence due to wave function collapse or other factors of 23% at the 90% confidence level.
Physical Review Letters 04/2009; 102(11):112301. · 7.37 Impact Factor
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B I Abelev,
M M Aggarwal,
Z Ahammed,
B D Anderson,
D Arkhipkin,
G S Averichev,
Y Bai,
J Balewski,
O Barannikova,
L S Barnby, [......],
S Zhang,
W M Zhang,
Y Zhang,
Z P Zhang,
Y Zhao,
C Zhong,
J Zhou,
R Zoulkarneev,
Y Zoulkarneeva,
J X Zuo
[show abstract]
[hide abstract]
ABSTRACT: Three-particle azimuthal correlation measurements with a high transverse momentum trigger particle are reported for pp, d+Au, and Au+Au collisions at sqrt[s_{NN}]=200 GeV by the STAR experiment. Dijet structures are observed in pp, d+Au and peripheral Au+Au collisions. An additional structure is observed in central Au+Au data, signaling conical emission of correlated charged hadrons. The conical emission angle is found to be theta=1.37+/-0.02(stat)-0.07+0.06(syst), independent of p_{ perpendicular}.
Physical Review Letters 03/2009; 102(5):052302. · 7.37 Impact Factor
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B I Abelev,
M M Aggarwal,
Z Ahammed,
B D Anderson,
D Arkhipkin,
G S Averichev,
Y Bai,
J Balewski,
O Barannikova,
L S Barnby, [......],
S Zhang,
W M Zhang,
Y Zhang,
Z P Zhang,
Y Zhao,
C Zhong,
J Zhou,
R Zoulkarneev,
Y Zoulkarneeva,
J X Zuo
[show abstract]
[hide abstract]
ABSTRACT: We measure directed flow (v_{1}) for charged particles in Au+Au and Cu+Cu collisions at sqrt[s_{NN}]=200 and 62.4 GeV, as a function of pseudorapidity (eta), transverse momentum (p_{t}), and collision centrality, based on data from the STAR experiment. We find that the directed flow depends on the incident energy but, contrary to all available model implementations, not on the size of the colliding system at a given centrality. We extend the validity of the limiting fragmentation concept to v_{1} in different collision systems, and investigate possible explanations for the observed sign change in v_{1}(p_{t}).
Physical Review Letters 01/2009; 101(25):252301. · 7.37 Impact Factor
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B I Abelev,
M M Aggarwal,
Z Ahammed,
B D Anderson,
D Arkhipkin,
G S Averichev,
Y Bai,
J Balewski,
O Barannikova,
L S Barnby, [......],
S Zhang,
W M Zhang,
Y Zhang,
Z P Zhang,
Y Zhao,
C Zhong,
J Zhou,
R Zoulkarneev,
Y Zoulkarneeva,
J X Zuo
[show abstract]
[hide abstract]
ABSTRACT: We report precision measurements of the Feynman x (xF) dependence, and first measurements of the transverse momentum (pT) dependence, of transverse single-spin asymmetries for the production of pi0 mesons from polarized proton collisions at sqrt[s] = 200 GeV. The xF dependence of the results is in fair agreement with perturbative QCD model calculations that identify orbital motion of quarks and gluons within the proton as the origin of the spin effects. Results for the pT dependence at fixed xF are not consistent with these same perturbative QCD-based calculations.
Physical Review Letters 12/2008; 101(22):222001. · 7.37 Impact Factor
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B I Abelev,
M M Aggarwal,
Z Ahammed,
B D Anderson,
D Arkhipkin,
G S Averichev,
Y Bai,
J Balewski,
O Barannikova,
L S Barnby, [......],
W M Zhang,
Y Zhang,
Z P Zhang,
Y Zhao,
C Zhong,
J Zhou,
R Zoulkarneev,
Y Zoulkarneeva,
A N Zubarev,
J X Zuo
[show abstract]
[hide abstract]
ABSTRACT: We report a new STAR measurement of the longitudinal double-spin asymmetry A(LL) for inclusive jet production at midrapidity in polarized p + p collisions at a center-of-mass energy of sqrt[s]=200 GeV. The data, which cover jet transverse momenta 5<p(T)<30 GeV/c, are substantially more precise than previous measurements. They provide significant new constraints on the gluon spin contribution to the nucleon spin through the comparison to predictions derived from one global fit to polarized deep-inelastic scattering measurements.
Physical Review Letters 06/2008; 100(23):232003. · 7.37 Impact Factor
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B I Abelev,
M M Aggarwal,
Z Ahammed,
B D Anderson,
D Arkhipkin,
G S Averichev,
Y Bai,
J Balewski,
O Barannikova,
L S Barnby, [......],
W M Zhang,
Y Zhang,
Z P Zhang,
Y Zhao,
C Zhong,
J Zhou,
R Zoulkarneev,
Y Zoulkarneeva,
A N Zubarev,
J X Zuo
[show abstract]
[hide abstract]
ABSTRACT: We present first measurements of the phi-meson elliptic flow (v2(pT)) and high-statistics pT distributions for different centralities from radical sNN=200 GeV Au+Au collisions at RHIC. In minimum bias collisions the v2 of the phi meson is consistent with the trend observed for mesons. The ratio of the yields of the Omega to those of the phi as a function of transverse momentum is consistent with a model based on the recombination of thermal s quarks up to pT approximately 4 GeV/c, but disagrees at higher momenta. The nuclear modification factor (R CP) of phi follows the trend observed in the K S 0 mesons rather than in Lambda baryons, supporting baryon-meson scaling. These data are consistent with phi mesons in central Au+Au collisions being created via coalescence of thermalized s quarks and the formation of a hot and dense matter with partonic collectivity at RHIC.
Physical Review Letters 10/2007; 99(11):112301. · 7.37 Impact Factor
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B I Abelev,
M M Aggarwal,
Z Ahammed,
B D Anderson,
D Arkhipkin,
G S Averichev,
Y Bai,
J Balewski,
O Barannikova,
L S Barnby, [......],
W M Zhang,
Y Zhang,
Z P Zhang,
Y Zhao,
C Zhong,
J Zhou,
R Zoulkarneev,
Y Zoulkarneeva,
A N Zubarev,
J X Zuo
[show abstract]
[hide abstract]
ABSTRACT: We report the first measurement of the opening angle distribution between pairs of jets produced in high-energy collisions of transversely polarized protons. The measurement probes (Sivers) correlations between the transverse spin orientation of a proton and the transverse momentum directions of its partons. With both beams polarized, the wide pseudorapidity (-1< or = eta < or = +2) coverage for jets permits separation of Sivers functions for the valence and sea regions. The resulting asymmetries are all consistent with zero and considerably smaller than Sivers effects observed in semi-inclusive deep inelastic scattering. We discuss theoretical attempts to reconcile the new results with the sizable transverse spin effects seen in semi-inclusive deep inelastic scattering and forward hadron production in pp collisions.
Physical Review Letters 10/2007; 99(14):142003. · 7.37 Impact Factor
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B I Abelev,
M M Aggarwal,
Z Ahammed,
B D Anderson,
D Arkhipkin,
G S Averichev,
Y Bai,
J Balewski,
O Barannikova,
L S Barnby, [......],
W M Zhang,
Y Zhang,
Z P Zhang,
Y Zhao,
C Zhong,
J Zhou,
R Zoulkarneev,
Y Zoulkarneeva,
A N Zubarev,
J X Zuo
[show abstract]
[hide abstract]
ABSTRACT: 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<p(T)<10 GeV/c) in p+p, d+Au, and Au+Au collisions at sqrt[s_{NN}]=200 GeV. The nonphotonic electron yield exhibits an unexpectedly large suppression in central Au+Au collisions at high p(T), suggesting substantial heavy-quark energy loss at RHIC. The centrality and p(T) dependences of the suppression provide constraints on theoretical models of suppression.
Physical Review Letters 05/2007; 98(19):192301. · 7.37 Impact Factor
