Transverse-momentum and collision-energy dependence of high-pT hadron suppression in Au+Au collisions at ultrarelativistic energies

Probing the Short-Distance Structure of the Quark-Gluon Plasma with Energy Correlators

Energy-energy correlators (EECs) are promising observables to study the dynamics of jet evolution in the quark-gluon plasma (QGP) through its imprint on angular scales in the energy flux of final-state particles. We carry out the first complete calculation of EECs using realistic simulations of high-energy heavy-ion collisions and dissect the different dynamics underlying the final distribution through analyses of jet propagation in a uniform medium. The EECs of γ-jets in heavy-ion collisions are found to be enhanced by the medium response from elastic scatterings instead of induced gluon radiation at large angles. In the meantime, EECs are suppressed at small angles due to energy loss and transverse momentum broadening of jet shower partons. These modifications are further shown to be sensitive to the angular scale of the in-medium interaction, as characterized by the Debye screening mass. Experimental verification and measurement of such modifications will shed light on this scale and the short-distance structure of the QGP in heavy-ion collisions.

Using Z Boson Events to Study Parton-Medium Interactions in Pb-Pb Collisions

The spectra measurements of charged hadrons produced in the shower of a parton originating in the same hard scattering with a leptonically decaying Z boson are reported in lead-lead nuclei (Pb-Pb) and proton-proton (pp) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. Both Pb-Pb and pp data sets are recorded by the CMS experiment at the LHC and correspond to an integrated luminosity of 1.7  nb^{-1} and 320  pb^{-1}, respectively. Hadronic collision data with one reconstructed Z boson candidate with the transverse momentum p_{T}>30  GeV/c are analyzed. The Z boson constrains the initial energy and direction of the associated parton. In heavy ion events, azimuthal angular distributions of charged hadrons with respect to the direction of a Z boson are sensitive to modifications of the in-medium parton shower and medium response. compared to reference data from pp interactions, the results for central Pb-Pb collisions indicate a modification of the angular correlations. The measurements of the fragmentation functions and p_{T} spectra of charged particles in Z boson events, which are sensitive to medium modifications of the parton shower longitudinal structure, are also reported. Significant modifications in central Pb-Pb events compared to the pp reference data are also found for these observables.

Jet Transport Coefficient at the Large Hadron Collider Energies in a Color String Percolation Approach

Within the color string percolation model (CSPM), jet transport coefficient, q^, is calculated for various multiplicity classes in proton-proton and centrality classes in nucleus-nucleus collisions at the Large Hadron Collider energies for a better understanding of the matter formed in ultra-relativistic collisions. q^ is studied as a function of final state charged particle multiplicity (pseudorapidity density at midrapidity), initial state percolation temperature and energy density. The CSPM results are then compared with different theoretical calculations from the JET Collaboration those incorporate particle energy loss in the medium.

Study of nuclear modification factors of deuteron and anti-deuteron in Pb-Pb collisions at [Formula: see text]

The nuclear modification factors ([Formula: see text]) of d and [Formula: see text] have been studied using the parton and hadron cascade model plus the dynamically constrained phase space coalescence model in peripheral (40-60%) and central (0-5%) Pb-Pb collisions at [Formula: see text] with [Formula: see text]. It is found that the [Formula: see text] of [Formula: see text] is similar to that of hadrons ([Formula: see text]) and the [Formula: see text] of antiparticles is the same as that of particles. The suppression effect of d is more significant than that of baryons and mesons in the high-[Formula: see text] region. The suppression of [Formula: see text] at high-[Formula: see text] strongly depends on event centrality and mass of the particles, i.e., the central collision is more suppressed than the peripheral collision. Besides, the yield ratios and double ratios for different particle species, and the coalescence parameter [Formula: see text] for ([Formula: see text]) in pp and Pb-Pb collisions are discussed, respectively. It is observed that the yield ratios and double ratios of d to p and p to [Formula: see text] are similar to those of their anti-particles in three different collision systems, suggesting that the suppressions of matter ([Formula: see text]) and the corresponding antimatter ([Formula: see text]) are around the same level.

First Observation of the Directed Flow of D^{0} and D^{0}[over ¯] in Au+Au Collisions at sqrt[s_{NN}]=200 GeV

We report the first measurement of rapidity-odd directed flow (v_{1}) for D^{0} and D^{0}[over ¯] mesons at midrapidity (|y|<0.8) in Au+Au collisions at sqrt[s_{NN}]=200  GeV using the STAR detector at the Relativistic Heavy Ion Collider. In 10-80% Au+Au collisions, the slope of the v_{1} rapidity dependence (dv_{1}/dy), averaged over D^{0} and D^{0}[over ¯] mesons, is -0.080±0.017(stat)±0.016(syst) for transverse momentum p_{T} above 1.5  GeV/c. The absolute value of D^{0} meson dv_{1}/dy is about 25 times larger than that for charged kaons, with 3.4σ significance. These data give a unique insight into the initial tilt of the produced matter, and offer constraints on the geometric and transport parameters of the hot QCD medium created in relativistic heavy-ion collisions.

Geometrical scaling of prompt photons in heavy ion collisions

We discuss geometrical scaling (GS) for the prompt (direct) photons produced in heavy ion collisions. To this end we first introduce the concept of GS and illustrate its emergence on the example of charged particles. Next, we analyse direct photon data from RHIC and from the LHC. We show that thedata supportthehypothesisofGSin termsof participant number relatedto different centrality classes. We also study GS at different energies, however a more detailed study will be possible only when data for at least three different energies from one experiment will be available and also when we use the data obtained from the collisions of large systems (Cu+Cu, Au+Au, Pb+Pb) and small systems (p+p,d+Au,p+Au).

The electron-ion collider: assessing the energy dependence of key measurements

We provide an assessment of the energy dependence of key measurements within the scope of the machine parameters for a US based electron-ion collider (EIC) outlined in the EIC White Paper. We first examine the importance of the physics underlying these measurements in the context of the outstanding questions in nuclear science. We then demonstrate, through detailed simulations of the measurements, that the likelihood of transformational scientific insights is greatly enhanced by making the energy range and reach of the EIC as large as practically feasible.

Measurement of the Splitting Function in pp and Pb-Pb Collisions at sqrt[s_{NN}]=5.02 TeV

Data from heavy ion collisions suggest that the evolution of a parton shower is modified by interactions with the color charges in the dense partonic medium created in these collisions, but it is not known where in the shower evolution the modifications occur. The momentum ratio of the two leading partons, resolved as subjets, provides information about the parton shower evolution. This substructure observable, known as the splitting function, reflects the process of a parton splitting into two other partons and has been measured for jets with transverse momentum between 140 and 500 GeV, in pp and PbPb collisions at a center-of-mass energy of 5.02 TeV per nucleon pair. In central PbPb collisions, the splitting function indicates a more unbalanced momentum ratio, compared to peripheral PbPb and pp collisions.. The measurements are compared to various predictions from event generators and analytical calculations.

Dijet imbalance measurements in Au+Au and pp collisions at sqrt[s_{NN}]=200 GeV at STAR

We report the first dijet transverse momentum asymmetry measurements from Au+Au and pp collisions at RHIC. The two highest-energy back-to-back jets reconstructed from fragments with transverse momenta above 2  GeV/c display a significantly higher momentum imbalance in heavy-ion collisions than in the pp reference. When reexamined with correlated soft particles included, we observe that these dijets then exhibit a unique new feature-momentum balance is restored to that observed in pp for a jet resolution parameter of R=0.4, while rebalancing is not attained with a smaller value of R=0.2.

Event-by-Event Hydrodynamics+Jet Energy Loss: A Solution to the R_{AA}⊗v_{2} Puzzle

High p_{T}>10  GeV elliptic flow, which is experimentally measured via the correlation between soft and hard hadrons, receives competing contributions from event-by-event fluctuations of the low-p_{T} elliptic flow and event-plane angle fluctuations in the soft sector. In this Letter, a proper account of these event-by-event fluctuations in the soft sector, modeled via viscous hydrodynamics, is combined with a jet-energy-loss model to reveal that the positive contribution from low-p_{T} v_{2} fluctuations overwhelms the negative contributions from event-plane fluctuations. This leads to an enhancement of high-p_{T}>10  GeV elliptic flow in comparison to previous calculations and provides a natural solution to the decade-long high-p_{T} R_{AA}⊗v_{2} puzzle. We also present the first theoretical calculation of high-p_{T} v_{3}, which is shown to be compatible with current LHC data. Furthermore, we discuss how short-wavelength jet-medium physics can be deconvoluted from the physics of soft, bulk event-by-event flow observables using event-shape engineering techniques.

Nuclear effects on the transverse momentum spectra of charged particles in pPb collisions at [Formula: see text][Formula: see text]

Transverse momentum spectra of charged particles are measured by the CMS experiment at the CERN LHC in pPb collisions at [Formula: see text][Formula: see text], in the range [Formula: see text][Formula: see text] and pseudorapidity [Formula: see text] in the proton-nucleon center-of-mass frame. For [Formula: see text][Formula: see text], the charged-particle production is asymmetric about [Formula: see text], with smaller yield observed in the direction of the proton beam, qualitatively consistent with expectations from shadowing in nuclear parton distribution functions (nPDF). A pp reference spectrum at [Formula: see text][Formula: see text] is obtained by interpolation from previous measurements at higher and lower center-of-mass energies. The [Formula: see text] distribution measured in pPb collisions shows an enhancement of charged particles with [Formula: see text][Formula: see text] compared to expectations from the pp reference. The enhancement is larger than predicted by perturbative quantum chromodynamics calculations that include antishadowing modifications of nPDFs.

Jet quenching phenomenology from soft-collinear effective theory with Glauber gluons

We present the first application of a recently developed effective theory of jet propagation in matter, soft-collinear effective theory with Glauber gluons (SCET_{G}), to inclusive hadron suppression in nucleus-nucleus collisions at RHIC and the LHC. SCET_{G}-based splitting kernels allow us to go beyond the traditional energy loss approximation and unify the treatment of vacuum and medium-induced parton showers. In the soft gluon emission limit, we establish a simple analytic relation between the QCD evolution and energy loss approaches to jet quenching. We quantify the uncertainties associated with the implementation of the in-medim modification of hadron production cross sections and show that the coupling between the jet and the medium can be constrained with better than 10% accuracy.

Measurements of the Nuclear Modification Factor for Jets in Pb+Pb Collisions at √(s)NN]=2.76 TeV with the ATLAS detector

Measurements of inclusive jet production are performed in pp and Pb+Pb collisions at √(s)NN=2.76  TeV with the ATLAS detector at the LHC, corresponding to integrated luminosities of 4.0 and 0.14  nb(-1), respectively. The jets are identified with the anti-k(t) algorithm with R=0.4, and the spectra are measured over the kinematic range of jet transverse momentum 32<p(T)<500  GeV and absolute rapidity |y|<2.1 and as a function of collision centrality. The nuclear modification factor R(AA) is evaluated, and jets are found to be suppressed by approximately a factor of 2 in central collisions compared to pp collisions. The R(AA) shows a slight increase with p(T) and no significant variation with rapidity.

Jet-hadron correlations in √[s(NN)]=200 GeV p+p and central Au+Au collisions

Azimuthal angular correlations of charged hadrons with respect to the axis of a reconstructed (trigger) jet in Au+Au and p+p collisions at √[s(NN)]=200  GeV in STAR are presented. The trigger jet population in Au+Au collisions is biased toward jets that have not interacted with the medium, allowing easier matching of jet energies between Au+Au and p+p collisions while enhancing medium effects on the recoil jet. The associated hadron yield of the recoil jet is significantly suppressed at high transverse momentum (pTassoc) and enhanced at low pTassoc in 0%-20% central Au+Au collisions compared to p+p collisions, which is indicative of medium-induced parton energy loss in ultrarelativistic heavy-ion collisions.

Identified hadron compositions in p+p and Au+Au collisions at high transverse momenta at √S(NN)=200 GeV

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.

Measurement of the bottom quark contribution to nonphotonic electron production in p + p collisions at √s=200 GeV

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.

Fast lattice Boltzmann solver for relativistic hydrodynamics

A lattice Boltzmann formulation for relativistic fluids is presented and numerically validated through quantitative comparison with recent hydrodynamic simulations of relativistic fluids. In order to illustrate its capability to handle complex geometries, the scheme is also applied to the case of a three-dimensional relativistic shock wave, generated by a supernova explosion, impacting on a massive interstellar cloud. This formulation opens up the possibility of exporting the proven advantages of lattice Boltzmann methods, namely, computational efficiency and easy handling of complex geometries, to the context of (mildly) relativistic fluid dynamics at large, from quark-gluon plasmas up to supernovae with relativistic outflows.

High transverse momentum triggered correlations over a large pseudorapidity acceptance in Au + Au collisions at square root(s(NN)) = 200 GeV

A measurement of two-particle correlations with a high transverse momentum trigger particle (p(T)(trig) > 2.5 GeV/c) is presented for Au+Au collisions at square root(s(NN)) = 200 GeV over the uniquely broad longitudinal acceptance of the PHOBOS detector (-4 < Delta eta < 2). A broadening of the away-side azimuthal correlation compared to elementary collisions is observed at all Delta eta. As in p+p collisions, the near side is characterized by a peak of correlated partners at small angle relative to the trigger particle. However, in central Au+Au collisions an additional correlation extended in Delta eta and known as the "ridge" is found to reach at least |Delta eta| approximately = 4. The ridge yield is largely independent of Delta eta over the measured range, and it decreases towards more peripheral collisions. For the chosen (p(T)(trig) cut, the ridge yield is consistent with zero for events with less than roughly 100 participating nucleons.

Azimuthal charged-particle correlations and possible local strong parity violation

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.

Energy loss for heavy quarks in relation to light partons: is radiative energy loss for heavy quarks anomalous?

The scaling properties of jet-suppression measurements are compared for nonphotonic electrons (e+/-) and neutral pions (pi(0)) in Au+Au collisions at sqrt[S(NN)]=200 GeV. For a broad range of transverse momenta and collision centralities, the comparison is consistent with jet quenching dominated by radiative energy loss for both heavy and light partons. Less quenching is indicated for heavy quarks via e+/-; this gives an independent estimate of the transport coefficient q that agrees with its magnitude obtained from quenching of light partons via pi(0)'s.

Relativistic shock waves in viscous gluon matter

We solve the relativistic Riemann problem in viscous gluon matter employing a microscopic parton cascade. We demonstrate the transition from ideal to viscous shock waves by varying the shear viscosity to entropy density ratio eta/s from zero to infinity. We show that an eta/s ratio larger than 0.2 prevents the development of well-defined shock waves on time scales typical for ultrarelativistic heavy-ion collisions. Comparisons with viscous hydrodynamic calculations confirm our findings.

Towards a unified understanding of jet quenching and elliptic flow within a perturbative QCD parton transport

The gluonic contribution to the nuclear modification factor R_{AA} is investigated for central Au + Au collisions at sqrt[s] = 200 AGeV employing a perturbative QCD-based parton cascade including radiative processes. A flat quenching pattern is found up to transverse momenta of 30 GeV, which is slightly smaller compared with results from the Gyulassy-Levai-Vitev formalism. We demonstrate that the present microscopic transport description provides a challenging means of investigating both jet quenching and a strong buildup of elliptic flow in terms of the same standard perturbative QCD interactions.

Relativistic diffusion

We discuss relativistic diffusion in proper time in the approach of Schay (Ph.D. thesis, Princeton University, Princeton, NJ, 1961) and Dudley [Ark. Mat. 6, 241 (1965)]. We derive (Langevin) stochastic differential equations in various coordinates. We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form. We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution. We discuss drag terms leading to an equilibrium distribution. The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Jüttner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed.

Onset of pi(0) suppression studied in Cu+Cu collisions at sqrt S NN=22.4, 62.4, and 200 GeV

Neutral pion transverse momentum (p(T)) spectra at midrapidity (|y| less than or approximately 0.35) were measured in Cu+Cu collisions at sqrt[s(NN)]=22.4, 62.4, and 200 GeV. Relative to pi_(0) yields in p+p collisions scaled by the number of inelastic nucleon-nucleon collisions (N(coll) the pi_(0) yields for p(T) more than or approximately 2 GeV/c in central Cu+Cu collisions are suppressed at 62.4 and 200 GeV whereas an enhancement is observed at 22.4 GeV. A comparison with a jet-quenching model suggests that final state parton energy loss dominates in central Cu+Cu collisions at 62.4 and 200 GeV, while the enhancement at 22.4 GeV is consistent with nuclear modifications in the initial state alone.

Particle-species dependent modification of jet-induced correlations in Au+Au collisions at sqrt[s_{NN}]=200 GeV

Measurements in Au+Au collisions at sqrt[s_{NN}]=200 GeV of jet correlations for a trigger hadron at intermediate transverse momentum (p_{T,trig}) with associated mesons or baryons at lower p_{T,assoc} indicate strong modification of the away-side jet. The ratio of jet-associated baryons to mesons increases with centrality and p_{T,assoc}. For the most central collisions, the ratio is similar to that for inclusive measurements. This trend is incompatible with in-vacuum fragmentation but could be due to jetlike contributions from correlated soft partons, which recombine upon hadronization.

Transverse momentum and centrality dependence of high-pT nonphotonic electron suppression in Au+Au collisions at sqrt[s NN]=200 GeV

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.

Longitudinal double-spin asymmetry and cross section for inclusive jet production in polarized proton collisions at square root of s = 200 GeV

We report a measurement of the longitudinal double-spin asymmetry A(LL) and the differential cross section for inclusive midrapidity jet production in polarized proton collisions at square root of s = 200 GeV. The cross section data cover transverse momenta 5 < pT < 50 GeV/c and agree with next-to-leading order perturbative QCD evaluations. The A(LL) data cover 5 < pT < 17 GeV/c and disfavor at 98% C.L. maximal positive gluon polarization in the polarized nucleon.

Direct observation of dijets in central Au+Au collisions at sqrt[sNN]=200 GeV

The STAR Collaboration at the Relativistic Heavy Ion Collider reports measurements of azimuthal correlations of high transverse momentum (pT) charged hadrons in Au+Au collisions at higher pT than reported previously. As (pT) is increased, a narrow, back-to-back peak emerges above the decreasing background, providing a clear dijet signal for all collision centralities studied. Using these correlations, we perform a systematic study of dijet production and suppression in nuclear collisions, providing new constraints on the mechanisms underlying partonic energy loss in dense matter.

Identified baryon and meson distributions at large transverse momenta from Au + Au collisions at square root sNN=200 GeV

Transverse momentum spectra of pi+/-, p, and p up to 12 GeV/c at midrapidity in centrality selected Au + Au collisions at square root sNN=200 GeV are presented. In central Au + Au collisions, both pi +/- and p(p) show significant suppression with respect to binary scaling at pT approximately >4 GeV/c. Protons and antiprotons are less suppressed than pi+/-, in the range 1.5 approximately < pT approximately < 6 GeV/c. The pi-/pi+ and p/p ratios show at most a weak pT dependence and no significant centrality dependence. The p/pi ratios in central Au + Au collisions approach the values in p + p and d + Au collisions at pT approximately >5 GeV/c. The results at high pT indicate that the partonic sources of pi+/-, p, and p have similar energy loss when traversing the nuclear medium.

Dense-medium modifications to jet-induced hadron pair distributions in Au+Au collisions at sqrt s NN=200 GeV

Azimuthal correlations of jet-induced high-p(T) charged hadron pairs are studied at midrapidity in Au+Au collisions at sqrt[s(NN)]=200 GeV. The distribution of jet-associated partner hadrons (1.0<p(T)<2.5 GeV/c) per trigger hadron (2.5<p(T)<4.0 GeV/c) is found to vary with collision centrality, in both shape and yield, indicating a significant effect of the nuclear collision medium on the jet fragmentation process.

System size and centrality dependence of charged hadron transverse momentum spectra in Au + Au and Cu + Cu collisions at square root of SNN = 62.4 and 200 GeV

We present transverse momentum distributions of charged hadrons produced in Cu + Cu collisions at square root of SNN = 62.4 and 200 GeV. The spectra are measured for transverse momenta of 0.25 < pT < 5.0 GeV/c at square root of SNN = 62.4 GeV and 0.25 < pT < 7.0 GeV/c at square root of SNN = 200 GeV, in a pseudorapidity range of 0.2 < eta < 1.4. The nuclear modification factor R(AA) is calculated relative to p + p data at both collision energies as a function of collision centrality. At a given collision energy and fractional cross section, R(AA) is observed to be systematically larger in Cu + Cu collisions compared to Au + Au. However, for the same number of participating nucleons, R(AA) is essentially the same in both systems over the measured range of pT, in spite of the significantly different geometries of the Cu + Cu and Au + Au systems.

Elliptic flow of thermal photons in relativistic nuclear collisions

We predict the transverse momentum (p(T)) dependence of elliptic flow of thermal photons for Au + Au collisions at the BNL Relativistic Heavy Ion Collider. We model the system hydrodynamically, with a thermalized quark-gluon plasma at early times followed by hadronization and decoupling. Photons are emitted throughout the expansion history. Contrary to hadron elliptic flow, which increases monotonically with p(T), the elliptic flow nu2(p(T)) of thermal photons is predicted to first rise and then fall again. Photon elliptic flow at high p(T) reflects the quark momentum anisotropy at early times when it is small, while at low p(T) it mirrors the large pion momentum anisotropy during the late hadronic emission stage. An interesting structure is predicted at intermediate p(T) approximately 0.4 GeV/c, where photon elliptic flow reflects the momenta and the (compared to pions) reduced nu2 of heavy vector mesons in the late hadronic phase.

Common suppression pattern of eta and pi0 mesons at high transverse momentum in Au + Au collisions at square root S(NN) = 200 GeV

Inclusive transverse momentum spectra of eta mesons have been measured within p(T) = 2-10 GeV/c at midrapidity by the PHENIX experiment in Au + Au collisions at square root S(NN) = 200 GeV. In central Au+Au the eta yields are significantly suppressed compared to peripheral Au + Au, d + Au, and p + p yields scaled by the corresponding number of nucleon-nucleon collisions. The magnitude, centrality, and p(T) dependence of the suppression is common, within errors, for eta and pi0. The ratio of eta to pi0 spectra at high p(T) amounts to 0.40 < R(eta/pi)0 < 0.48 for the three systems, in agreement with the world average measured in hadronic and nuclear reactions and, at large scaled momentum, in e+e- collisions.