| 1. |
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| 2. |
- Adare, A., et al.
(author)
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Measurements of Elliptic and Triangular Flow in High-Multiplicity He-3 + Au Collisions at root s(NN)=200 GeV
- 2015
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In: Physical Review Letters. - 1079-7114. ; 115:14
-
Journal article (peer-reviewed)abstract
- We present the first measurement of elliptic (v(2)) and triangular (v(3)) flow in high-multiplicity He-3 + Au collisions at root s(NN) = 200 GeV. Two-particle correlations, where the particles have a large separation in pseudorapidity, are compared in He-3 + Au and in p + p collisions and indicate that collective effects dominate the second and third Fourier components for the correlations observed in the He-3 + Au system. The collective behavior is quantified in terms of elliptic v(2) and triangular v(3) anisotropy coefficients measured with respect to their corresponding event planes. The v(2) values are comparable to those previously measured in d + Au collisions at the same nucleon-nucleon center-of-mass energy. Comparisons with various theoretical predictions are made, including to models where the hot spots created by the impact of the three He-3 nucleons on the Au nucleus expand hydrodynamically to generate the triangular flow. The agreement of these models with data may indicate the formation of low-viscosity quark-gluon plasma even in these small collision systems.
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| 3. |
- Adare, A., et al.
(author)
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Search for dark photons from neutral meson decays in p plus p and d plus Au collisions at root s(NN)=200 GeV
- 2015
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 91:3
-
Journal article (peer-reviewed)abstract
- The standard model (SM) of particle physics is spectacularly successful, yet the measured value of the muon anomalous magnetic moment (g - 2)mu deviates from SM calculations by 3.6 sigma. Several theoretical models attribute this to the existence of a "dark photon," an additional U(1) gauge boson, which is weakly coupled to ordinary photons. The PHENIX experiment at the Relativistic Heavy Ion Collider has searched for a dark photon, U, in pi(0), eta -> gamma e(+)e(-) decays and obtained upper limits of O(2 x 10(-6)) on U-gamma mixing at 90% C.L. for the mass range 30 < m(U) < 90 MeV/c(2). Combined with other experimental limits, the remaining region in the U-gamma mixing parameter space that can explain the (g - 2)(mu) deviation from its SM value is nearly completely excluded at the 90% confidence level, with only a small region of 29 < m(U) < 32 MeV/c(2) remaining.
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| 4. |
- Adare, A., et al.
(author)
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Medium Modification of Jet Fragmentation in Au plus Au Collisions at root S-NN=200 GeV Measured in Direct Photon-Hadron Correlations
- 2013
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In: Physical Review Letters. - 1079-7114. ; 111:3
-
Journal article (peer-reviewed)abstract
- The jet fragmentation function is measured with direct photon-hadron correlations in p + p and Au + Au collisions at root S-NN = 200 GeV. The P-T of the photon is an excellent approximation to the initial P-T of the jet and the ratio Z(T) = P-T(h)/P-T(gamma) is used as a proxy for the jet fragmentation function. A statistical subtraction is used to extract the direct photon-hadron yields in Au + Au collisions while a photon isolation cut is applied in p + p. I-AA, the ratio of hadron yield opposite the photon in Au + Au to that in p + p, indicates modification of the jet fragmentation function. Suppression, most likely due to energy loss in the medium, is seen at high Z(T). The associated hadron yield at low Z(T) is enhanced at large angles. Such a trend is expected from redistribution of the lost energy into increased production of low-momentum particles.
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| 5. |
- Adare, A., et al.
(author)
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Direct photon production in d+Au collisions at root s(NN)=200 GeV
- 2013
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 87:5
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Journal article (peer-reviewed)abstract
- Direct photons have been measured in root s(NN) = 200 GeV d + Au collisions at midrapidity. A wide p(T) range is covered by measurements of nearly real virtual photons (1 < p(T) < 6 GeV/c) and real photons (5 < p(T) < 16 GeV/c). The invariant yield of the direct photons in d + Au collisions over the scaled p + p cross section is consistent with unity. Theoretical calculations assuming standard cold-nuclear-matter effects describe the data well for the entire p(T) range. This indicates that the large enhancement of direct photons observed in Au + Au collisions for 1.0 < p(T) < 2.5 GeV/c is attributable to a source other than the initial-state nuclear effects.
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| 6. |
- Adare, A., et al.
(author)
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Measurement of gamma(1S+2S+3S) production in p plus p and Au plus Au collisions at root sNN=200 GeV
- 2015
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 91:2
-
Journal article (peer-reviewed)abstract
- Measurements of bottomonium production in heavy-ion and p + p collisions at the Relativistic Heavy Ion Collider (RHIC) are presented. The inclusive yield of the three states, (1S + 2S + 3S), was measured in the PHENIX experiment via electron-positron decay pairs at midrapidity for Au + Au and p + p collisions at root sNN = 200 GeV. The (1S + 2S + 3S) -> e(+)e(-) differential cross section at midrapidity was found to be B(ee)d sigma/dy = 108 +/- 38 (stat) +/- 15 (syst) +/- 11 (luminosity) pb in p + p collisions. The nuclear modification factor in the 30% most central Au + Au collisions indicates a suppression of the total. state yield relative to the extrapolation from p + p collision data. The suppression is consistent with measurements made by STAR at RHIC and at higher energies by the CMS experiment at the Large Hadron Collider.
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| 7. |
- Adare, A., et al.
(author)
-
gamma (1S+2S+3S) production in d plus Au and p plus p collisions at root s(NN)=200 GeV and cold-nuclear-matter effects
- 2013
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 87:4
-
Journal article (peer-reviewed)abstract
- The three gamma states, gamma (1S + 2S + 3S), are measured in d + Au and p + p collisions at root s(NN) = 200 GeV and rapidities 1.2 < vertical bar y vertical bar < 2.2 by the PHENIX experiment at the Relativistic Heavy Ion Collider. Cross sections for the inclusive gamma (1S + 2S + 3S) production are obtained. The inclusive yields per binary collision for d + Au collisions relative to those in p + p collisions (R-dAu) are found to be 0.62 +/- 0.26 (stat) +/- 0.13 (syst) in the gold-going direction and 0.91 +/- 0.33 (stat) +/- 0.16 (syst) in the deuteron-going direction. The measured results are compared to a nuclear-shadowing model, EPS09 [Eskola et al., J. High Energy Phys. 04 (2009) 065], combined with a final-state breakup cross section, sigma(br), and compared to lower energy p + A results. We also compare the results to the PHENIX J/psi results [Adare et al., Phys. Rev. Lett. 107, 142301 (2011)]. The rapidity dependence of the observed gamma suppression is consistent with lower energy p + A measurements. DOI: 10.1103/PhysRevC.87.044909
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| 8. |
- Adare, A., et al.
(author)
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Photon-hadron jet correlations in p plus p and Au plus Au collisions at s(NN)=200 GeV
- 2009
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 80:2
-
Journal article (peer-reviewed)abstract
- We report the observation at the Relativistic Heavy Ion Collider of suppression of back-to-back correlations in the direct photon+jet channel in Au+Au relative to p+p collisions. Two-particle correlations of direct photon triggers with associated hadrons are obtained by statistical subtraction of the decay photon-hadron (gamma-h) background. The initial momentum of the away-side parton is tightly constrained, because the parton-photon pair exactly balance in momentum at leading order in perturbative quantum chromodynamics, making such correlations a powerful probe of the in-medium parton energy loss. The away-side nuclear suppression factor, I-AA, in central Au+Au collisions, is 0.32 +/- 0.12(stat)+/- 0.09(syst) for hadrons of 3 < p(T)(h)< 5 in coincidence with photons of 5 < p(T)(gamma)< 15 GeV/c. The suppression is comparable to that observed for high-p(T) single hadrons and dihadrons. The direct photon associated yields in p+p collisions scale approximately with the momentum balance, z(T)equivalent to p(T)(h)/p(T)(gamma), as expected for a measurement of the away-side parton fragmentation function. We compare to Au+Au collisions for which the momentum balance dependence of the nuclear modification should be sensitive to the path-length dependence of parton energy loss.
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| 9. |
- Adare, A., et al.
(author)
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Cold Nuclear Matter Effects on J/psi Yields as a Function of Rapidity and Nuclear Geometry in d plus A Collisions at root S-NN=200 GeV
- 2011
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In: Physical Review Letters. - 1079-7114. ; 107:14
-
Journal article (peer-reviewed)abstract
- We present measurements of J/psi yields in d + Au collisions at root S-NN = 200 GeV recorded by the PHENIX experiment and compare them with yields in p + p collisions at the same energy per nucleon-nucleon collision. The measurements cover a large kinematic range in J/psi rapidity (-2.2 < y < 2.4) with high statistical precision and are compared with two theoretical models: one with nuclear shadowing combined with final state breakup and one with coherent gluon saturation effects. In order to remove model dependent systematic uncertainties we also compare the data to a simple geometric model. The forward rapidity data are inconsistent with nuclear modifications that are linear or exponential in the density weighted longitudinal thickness, such as those from the final state breakup of the bound state.
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| 10. |
- Adare, A., et al.
(author)
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Ground and excited state charmonium production in p plus p collisions at root s=200 GeV
- 2012
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In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 85:9
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Journal article (peer-reviewed)abstract
- We report on charmonium measurements [J/psi (1S), psi' (2S), and chi(c) (1P)] in p + p collisions at root s = 200 GeV. We find that the fraction of J/psi coming from the feed-down decay of psi' and chi(c) in the midrapidity region (vertical bar y vertical bar < 0: 35) is 9.6 +/- 2.4% and 32 +/- 9%, respectively. We also present the p(T) and rapidity dependencies of the J/psi yield measured via dielectron decay at midrapidity (vertical bar y vertical bar < 0.35) and via dimuon decay at forward rapidity (1.2 < vertical bar y vertical bar < 2.2). The statistical precision greatly exceeds that reported in our previous publication [Phys. Rev. Lett. 98, 232002 (2007)]. The new results are compared with other experiments and discussed in the context of current charmonium production models.
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| 11. |
- Adare, A., et al.
(author)
-
Heavy-flavor electron-muon correlations in p plus p and d plus Au collisions at root s(NN)=200 GeV
- 2014
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 89:3
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Journal article (peer-reviewed)abstract
- Background: Heavy-flavor modification in relativistic p(d) + A collisions are sensitive to different kinds of strong-interaction physics ranging from modifications of the nuclear wave function to initial- and final-state energy loss. Modifications to single heavy-flavor particles and their decay leptons at midrapidity and forward rapidity are well established at the Relativistic Heavy Ion Collider (RHIC). Purpose: This paper presents measurements of azimuthal correlations of electron-muon pairs produced from heavy-flavor decays, primarily c (c) over bar, in root s(NN) = 200 GeV p + p and d + Au collision using the PHENIX detector at RHIC. The electrons are measured at midrapidity while the muons in the pair are measured at forward rapidity, defined as the direction of the deuteron beam, in order to utilize the deuteron to probe low-x partons in the gold nucleus. Methods: This analysis uses the central spectrometer arms for electron identification and forward spectrometer arms for muon identification. Azimuthal correlations are built in all sign combinations for e-mu pairs. Subtracting the like-sign yield from the unlike-sign yield removes the correlations from light flavor decays and conversions. Results: Comparing the p + p results with several different Monte Carlo event generators, we find the results are consistent with a total charm cross section sigma(c (c) over bar) = 538 +/- 46 (stat) +/- 197 (data syst) +/- 174 (model syst) mu b. These generators also indicate that the back-to-back peak at Delta phi = pi is dominantly from the leading-order contributions (gluon fusion), while higher-order processes (flavor excitation and gluon splitting) contribute to the yield at all Delta phi. We observe a suppression in the pair yield per collision in d + Au. We find the pair yield suppression factor for 2.7 < Delta phi < 3.2 rad is J(dA) = 0.433 +/- 0.087 (stat) +/- 0.135 (syst). Conclusions: The e-mu pairs result from partons at x(Au) similar to 10(-2) at Q(2) = 10 GeV/c(2) at the edge of the shadowing region. The pair suppression indicates modification to c (c) over bar pairs for these kinematics in the cold nuclear medium at RHIC.
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| 12. |
- Adare, A., et al.
(author)
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Measurement of transverse single-spin asymmetries for J/psi production in polarized p plus p collisions at root s=200 GeV
- 2010
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In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 82:11
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Journal article (peer-reviewed)abstract
- We report the first measurement of transverse single-spin asymmetries in J/psi production from transversely polarized p + p collisions at root s = 200 GeV with data taken by the PHENIX experiment in 2006 and 2008. The measurement was performed over the rapidity ranges 1.2 < vertical bar y vertical bar < 2.2 and vertical bar y vertical bar < 0.35 for transverse momenta up to 6 GeV/c. J/psi production at the Relativistic Heavy Ion Collider is dominated by processes involving initial-state gluons, and transverse single-spin asymmetries of the J/psi can provide access to gluon dynamics within the nucleon. Such asymmetries may also shed light on the long-standing question in QCD of the J/psi production mechanism. Asymmetries were obtained as a function of J/psi transverse momentum and Feynman-x, with a value of -0.086 +/- 0.026(stat) +/- 0.003(syst) in the forward region. This result suggests possible nonzero trigluon correlation functions in transversely polarized protons and, if well defined in this reaction, a nonzero gluon Sivers distribution function.
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| 13. |
- Adare, A., et al.
(author)
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Measurement of transverse-single-spin asymmetries for midrapidity and forward-rapidity production of hadrons in polarized p plus p collisions at root s=200 and 62.4 GeV
- 2014
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In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 90:1
-
Journal article (peer-reviewed)abstract
- Measurements of transverse-single-spin asymmetries (A(N)) in p + p collisions at root s = 62.4 and 200 GeV with the PHENIX detector at the Relativistic Heavy Ion Collider are presented. At midrapidity, A(N) is measured for neutral pion and eta mesons reconstructed from diphoton decay, and, at forward rapidities, neutral pions are measured using both diphotons and electromagnetic clusters. The neutral-pion measurement of A(N) at midrapidity is consistent with zero with uncertainties a factor of 20 smaller than previous publications, which will lead to improved constraints on the gluon Sivers function. At higher rapidities, where the valence quark distributions are probed, the data exhibit sizable asymmetries. In comparison with previous measurements in this kinematic region, the new data extend the kinematic coverage in root s and p(T), and it is found that the asymmetries depend only weakly on root s. The origin of the forward A(N) is presently not understood quantitatively. The extended reach to higher p(T) probes the transition between transverse momentum dependent effects at low p(T) and multiparton dynamics at high p(T).
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| 14. |
- Adare, A., et al.
(author)
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Cross section and double helicity asymmetry for eta mesons and their comparison to pi(0) production in p plus p collisions at root s=200 GeV
- 2011
-
In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 83:3
-
Journal article (peer-reviewed)abstract
- Measurements of double-helicity asymmetries in inclusive hadron production in polarized p + p collisions are sensitive to helicity-dependent parton distribution functions, in particular, to the gluon helicity distribution, Delta g. This study focuses on the extraction of the double-helicity asymmetry in eta production ((p) over right arrow + (p) over right arrow -> eta + X), the eta cross section, and the eta/pi(0) cross section ratio. The cross section and ratio measurements provide essential input for the extraction of fragmentation functions that are needed to access the helicity-dependent parton distribution functions.
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| 15. |
- Adare, A., et al.
(author)
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High p(T) direct photon and pi(0) triggered azimuthal jet correlations and measurement of k(T) for isolated direct photons in p plus p collisions at root s=200 GeV
- 2010
-
In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 82:7
-
Journal article (peer-reviewed)abstract
- Correlations of charged hadrons of 1< p(T) < 10 Gev/c with high pT direct photons and pi(0) mesons in the range 5< p(T) < 15 Gev/c are used to study jet fragmentation in the gamma + jet and dijet channels, respectively. The magnitude of the partonic transverse momentum, k(T), is obtained by comparing to a model incorporating a Gaussian kT smearing. The sensitivity of the associated charged hadron spectra to the underlying fragmentation function is tested and the data are compared to calculations using recent global fit results. The shape of the direct photon-associated hadron spectrum as well as its charge asymmetry are found to be consistent with a sample dominated by quark-gluon Compton scattering. No significant evidence of fragmentation photon correlated production is observed within experimental uncertainties.
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| 16. |
- Adare, A., et al.
(author)
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Measurement of Bottom Versus Charm as a Function of Transverse Momentum with Electron-Hadron Correlations in p plus p Collisions at s=200 GeV
- 2009
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In: Physical Review Letters. - 1079-7114. ; 103:8
-
Journal article (peer-reviewed)abstract
- The momentum distribution of electrons from semileptonic decays of charm and bottom quarks for midrapidity |y|< 0.35 in p+p collisions at s=200 GeV is measured by the PHENIX experiment at the Relativistic Heavy Ion Collider over the transverse momentum range 2 < p(T)< 7 GeV/c. The ratio of the yield of electrons from bottom to that from charm is presented. The ratio is determined using partial D/D -> e(+/-)K(-/+)X (K unidentified) reconstruction. It is found that the yield of electrons from bottom becomes significant above 4 GeV/c in p(T). A fixed-order-plus-next-to-leading-log perturbative quantum chromodynamics calculation agrees with the data within the theoretical and experimental uncertainties. The extracted total bottom production cross section at this energy is sigma(bb)=3.2(-1.1)(+1.2)(stat)(-1.3)(+1.4)(syst)mu b.
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| 17. |
- Adare, A., et al.
(author)
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Onset of pi(0) Suppression Studied in Cu plus Cu Collisions at root s(NN)=22.4, 62.4, and 200 GeV
- 2008
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In: Physical Review Letters. - 1079-7114. ; 101:16
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Journal article (peer-reviewed)abstract
- Neutral pion transverse momentum (p(T)) spectra at midrapidity (|y| less than or similar to 0.35) were measured in Cu + Cu collisions at root 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) greater than or similar to 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.
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| 18. |
- Adare, A., et al.
(author)
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Transition in Yield and Azimuthal Shape Modification in Dihadron Correlations in Relativistic Heavy Ion Collisions
- 2010
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In: Physical Review Letters. - 1079-7114. ; 104:25
-
Journal article (peer-reviewed)abstract
- Hard-scattered parton probes produced in collisions of large nuclei indicate large partonic energy loss, possibly with collective produced-medium response to the lost energy. We present measurements of pi(0) trigger particles at transverse momenta p(T)(t) = 4-12 GeV/c and associated charged hadrons (p(T)(a) = 0.5-7 GeV/c) vs relative azimuthal angle Delta phi in Au + Au and p + p collisions at root s(NN) = 200 GeV. The Au + Au distribution at low p(T)(a), whose shape has been interpreted as a medium effect, is modified for p(T)(t) < 7 GeV/c. At higher p(T)(t), the data are consistent with unmodified or very weakly modified shapes, even for the lowest measured p(T)(a), which quantitatively challenges some medium response models. The associated yield of hadrons opposing the trigger particle in Au + Au relative to p + p (I-AA) is suppressed at high p(T) (I-AA approximate to 0.35-0.5), but less than for inclusive suppression (R-AA approximate to 0.2).
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| 19. |
- Adare, A., et al.
(author)
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Transverse momentum dependence of eta meson suppression in Au plus Au collisions at root s(NN)=200 GeV
- 2010
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 82:1
-
Journal article (peer-reviewed)abstract
- New measurements by the PHENIX experiment at the Relativistic Heavy Ion Collider for. production at midrapidity as a function of transverse momentum ((PT)) and collision centrality in root s(NN) = 200 GeV Au + Au and p + p collisions are presented. They indicate nuclear modification factors (R-AA) which are similar in both magnitude and trend to those found in earlier pi(0) measurements. Linear fits to R-AA as a function of (PT) in 5-20 GeV/c show that the slope is consistent with zero within two standard deviations at all centralities, although a slow rise cannot be excluded. Having different statistical and systematic uncertainties, the pi(0) and eta measurements are complementary at high (PT); thus, along with the extended (PT) range of these data they can provide additional constraints for theoretical modeling and the extraction of transport properties.
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| 20. |
- Adare, A., et al.
(author)
-
Azimuthal correlations of electrons from heavy-flavor decay with hadrons in p plus p and Au plus Au collisions at root s(NN)=200 GeV
- 2011
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 83:4
-
Journal article (peer-reviewed)abstract
- Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled p+p collisions. These measurements indicate that charm and bottom quarks interact with the hot dense matter produced in heavy-ion collisions much more than expected. Here we extend these studies to two-particle correlations where one particle is an electron from the decay of a heavy-flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interactions between heavy quarks and the matter, such as whether the modification of the away-side-jet shape seen in hadron-hadron correlations is present when the trigger particle is from heavy-meson decay and whether the overall level of away-side-jet suppression is consistent. We statistically subtract correlations of electrons arising from background sources from the inclusive electron-hadron correlations and obtain two-particle azimuthal correlations at root s(NN) = 200 GeV between electrons from heavy-flavor decay with charged hadrons in p+p and also first results in Au+Au collisions. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to p+p collisions.
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| 21. |
- Adare, A., et al.
(author)
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Identified charged hadron production in p plus p collisions at root s=200 and 62.4 GeV
- 2011
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 83:6
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Journal article (peer-reviewed)abstract
- Transverse momentum distributions and yields for pi(+/-), K-+/-, p, and (p) over bar in p + p collisions at root s = 200 and 62.4 GeV at midrapidity are measured by the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC). These data provide important baseline spectra for comparisons with identified particle spectra in heavy ion collisions at RHIC. We present the inverse slope parameter T-inv, mean transverse momentum < p(T)>, and yield per unit rapidity dN/dy at each energy, and compare them to other measurements at different root s in p + p and p + (p) over bar collisions. We also present the scaling properties such as m(T) scaling and x(T) scaling on the p(T) spectra between different energies. To discuss the mechanism of the particle production in p + p collisions, the measured spectra are compared to next-to-leading-order or next-to-leading-logarithmic perturbative quantum chromodynamics calculations.
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| 22. |
- Adare, A., et al.
(author)
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Measurement of neutral mesons in p plus p collisions at root s=200 GeV and scaling properties of hadron production
- 2011
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In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 83:5
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Journal article (peer-reviewed)abstract
- The PHENIX experiment at the Relativistic Heavy Ion Collider has measured the invariant differential cross section for production of K-S(0), omega, eta', and phi mesons in p + p collisions at root s 200 GeV. Measurements of omega and phi production in different decay channels give consistent results. New results for the omega are in agreement with previously published data and extend the measured p(T) coverage. The spectral shapes of all hadron transverse momentum distributions measured by PHENIX are well described by a Tsallis distribution functional form with only two parameters, n and T, determining the high-p(T) and characterizing the low-p(T) regions of the spectra, respectively. The values of these parameters are very similar for all analyzed meson spectra, but with a lower parameter T extracted for protons. The integrated invariant cross sections calculated from the fitted distributions are found to be consistent with existing measurements and with statistical model predictions.
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| 23. |
- Adare, A., et al.
(author)
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Suppression of away-side jet fragments with respect to the reaction plane in Au plus Au collisions at root s(NN)=200 GeV
- 2011
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 84:2
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Journal article (peer-reviewed)abstract
- Pair correlations between large transverse momentum neutral pion triggers (p(T) = 4-7 GeV/c) and charged hadron partners (p(T) = 3-7 GeV/c) in central (0%-20%) and midcentral (20%-60%) Au + Au collisions at root s(NN) = 200 GeV are presented as a function of trigger orientation with respect to the reaction plane. The particles are at larger momentum than where jet shape modifications have been observed, and the correlations are sensitive to the energy loss of partons traveling through hot densematter. An out-of-plane trigger particle produces only 26 +/- 20% of the away-side pairs that are observed opposite of an in-plane trigger particle for midcentral (20%-60%) collisions. In contrast, near-side jet fragments are consistent with no suppression or dependence on trigger orientation with respect to the reaction plane. These observations are qualitatively consistent with a picture of little near-side parton energy loss either due to surface bias or fluctuations and increased away-side parton energy loss due to a long path through the medium. The away-side suppression as a function of reaction-plane angle is shown to be sensitive to both the energy loss mechanism and the space-time evolution of heavy-ion collisions.
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| 24. |
- Adare, A., et al.
(author)
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Gluon-Spin Contribution to the Proton Spin from the Double-Helicity Asymmetry in Inclusive pi(0) Production in Polarized p plus p Collisions at root s=200 GeV
- 2009
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In: Physical Review Letters. - 1079-7114. ; 103:1
-
Journal article (peer-reviewed)abstract
- The double helicity asymmetry in neutral pion production for p(T) = 1 to 12 GeV/c was measured with the PHENIX experiment to access the gluon-spin contribution, Delta G, to the proton spin. Measured asymmetries are consistent with zero, and at a theory scale of mu 2 = 4 GeV2 a next to leading order QCD analysis gives Delta G([0.02,0.3]) = 0.2, with a constraint of -0.7 < Delta G([0.02,0.3]) < 0.5 at Delta chi(2) = 9 (similar to 3 sigma) for the sampled gluon momentum fraction (x) range, 0.02 to 0.3. The results are obtained using predictions for the measured asymmetries generated from four representative fits to polarized deep inelastic scattering data. We also consider the dependence of the Delta G constraint on the choice of the theoretical scale, a dominant uncertainty in these predictions.
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| 25. |
- Adare, A., et al.
(author)
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Cross sections and double-helicity asymmetries of midrapidity inclusive charged hadrons in p plus p collisions at root s = 62.4 GeV
- 2012
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In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 86:9
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Journal article (peer-reviewed)abstract
- Unpolarized cross sections and double-helicity asymmetries of single-inclusive positive and negative charged hadrons at midrapidity from p + p collisions at root s = 62.4 GeV are presented. The PHENIX measurement of the cross sections for 1.0 < p(T) < 4.5 GeV/c are consistent with perturbative QCD calculations at next-to-leading order in the strong-coupling constant, alpha(s). Resummed pQCD calculations including terms with next-to-leading-log accuracy, yielding reduced theoretical uncertainties, also agree with the data. The double-helicity asymmetry, sensitive at leading order to the gluon polarization in a momentum-fraction range of 0.05 less than or similar to x(gluon) less than or similar to 0.2, is consistent with recent global parametrizations disfavoring large gluon polarization.
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| 26. |
- Adare, A., et al.
(author)
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Inclusive cross section and double helicity asymmetry for pi(0) production in p plus p collisions at root s=62.4 GeV
- 2009
-
In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 79:1
-
Journal article (peer-reviewed)abstract
- The PHENIX experiment presents results from the RHIC 2006 run with polarized p + p collisions at root s = 62.4 GeV, for inclusive pi(0) production at midrapidity. Unpolarized cross section results are measured for transverse momenta p(T) = 0.5 to 7 GeV/c. Next-to-leading order perturbative quantum chromodynamics calculations are compared with the data, and while the calculations are consistent with the measurements, next-to-leading logarithmic corrections improve the agreement. Double helicity asymmetries A(LL) are presented for p(T) = 1 to 4 GeV/c and probe the higher range of Bjorken x of the gluon (x(g)) with better statistical precision than our previous measurements at root s = 200 GeV. These measurements are sensitive to the gluon polarization in the proton for 0.06 < x(g) < 0.4.
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| 27. |
- Adare, A., et al.
(author)
-
Direct photon production in p plus p collisions at root s=200 GeV at midrapidity
- 2012
-
In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 86:7
-
Journal article (peer-reviewed)abstract
- The differential cross section for the production of direct photons in p + p collisions at root s = 200 GeV at midrapidity was measured in the PHENIX detector at the Relativistic Heavy Ion Collider. Inclusive direct photons were measured in the transverse momentum range from 5: 5-25 GeV/c, extending the range beyond previous measurements. Event structure was studied with an isolation criterion. Next-to-leading-order perturbative-quantum-chromodynamics calculations give a good description of the spectrum. When the cross section is expressed versus x(T), the PHENIX data are seen to be in agreement with measurements from other experiments at different center-of-mass energies.
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| 28. |
- Adare, A., et al.
(author)
-
Inclusive cross section and single transverse spin asymmetry for very forward neutron production in polarized p plus p collisions at root s=200 GeV
- 2013
-
In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 88:3
-
Journal article (peer-reviewed)abstract
- The energy dependence of the single-transverse-spin asymmetry, A(N), and the cross section for neutron production at very forward angles were measured in the PHENIX experiment at the Relativistic Heavy Ion Collider for polarized p + p collisions at root s = 200 GeV. The neutrons were observed in forward detectors covering an angular range of up to 2.2 mrad. We report results for neutrons with a momentum fraction of x(F) = 0.45 to 1.0. The energy dependence of the measured cross sections were consistent with x(F) scaling, compared to measurements by an experiment at the Intersecting Storage Ring, which measured neutron production in unpolarized p + p collisions at root s = 30.6-62.7 GeV. The cross sections for large x(F) neutron production for p + p collisions, as well as those in e + p collisions measured at the Hadron-Electron Ring Accelerator, are described by a pion exchange mechanism. The observed forward neutron asymmetries were large, reaching A(N) = -0.08 +/- 0.02 for x(F) = 0.8; the measured backward asymmetries, for negative x(F), were consistent with zero. The observed asymmetry for forward neutron production is discussed within the pion exchange framework, with interference between the spin-flip amplitude due to the pion exchange and nonflip amplitudes from all Reggeon exchanges. Within the pion exchange description, the measured neutron asymmetry is sensitive to the contribution of other Reggeon exchanges even for small amplitudes.
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| 29. |
- Adare, A., et al.
(author)
-
Transverse momentum dependence of J/psi polarization at midrapidity in p plus p collisions at root s=200 GeV
- 2010
-
In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 82:1
-
Journal article (peer-reviewed)abstract
- We report the measurement of the transverse momentum dependence of inclusive J/psi polarization in p + p collisions at root s = 200 GeV performed by the PHENIX Experiment at the Relativistic Heavy Ion Collider. The J/psi polarization is studied in the helicity, Gottfried-Jackson, and Collins-Soper frames for p(T) < 5 GeV/c and vertical bar y vertical bar < 0.35. The polarization in the helicity and Gottfried-Jackson frames is consistent with zero for all transverse momenta, with a slight (1.8 sigma) trend towards longitudinal polarization for transverse momenta above 2 GeV/c. No conclusion is allowed due to the limited acceptance in the Collins-Soper frame and the uncertainties of the current data. The results are compared to observations for other collision systems and center of mass energies and to different quarkonia production models.
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| 30. |
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| 31. |
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| 32. |
- Cronin, M. F., et al.
(author)
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Developing an Observing Air-Sea Interactions Strategy (OASIS) for the global ocean
- 2022
-
In: Ices Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 80:2, s. 367-73
-
Journal article (peer-reviewed)abstract
- The Observing Air-Sea Interactions Strategy (OASIS) is a new United Nations Decade of Ocean Science for Sustainable Development programme working to develop a practical, integrated approach for observing air-sea interactions globally for improved Earth system (including ecosystem) forecasts, CO2 uptake assessments called for by the Paris Agreement, and invaluable surface ocean information for decision makers. Our "Theory of Change" relies upon leveraged multi-disciplinary activities, partnerships, and capacity strengthening. Recommendations from >40 OceanObs'19 community papers and a series of workshops have been consolidated into three interlinked Grand Ideas for creating #1: a globally distributed network of mobile air-sea observing platforms built around an expanded array of long-term time-series stations; #2: a satellite network, with high spatial and temporal resolution, optimized for measuring air-sea fluxes; and #3: improved representation of air-sea coupling in a hierarchy of Earth system models. OASIS activities are organized across five Theme Teams: (1) Observing Network Design & Model Improvement; (2) Partnership & Capacity Strengthening; (3) UN Decade OASIS Actions; (4) Best Practices & Interoperability Experiments; and (5) Findable-Accessible-Interoperable-Reusable (FAIR) models, data, and OASIS products. Stakeholders, including researchers, are actively recruited to participate in Theme Teams to help promote a predicted, safe, clean, healthy, resilient, and productive ocean.
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| 33. |
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| 34. |
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| 35. |
- Oprea, Tudor I, et al.
(author)
-
Unexplored therapeutic opportunities in the human genome
- 2018
-
In: Nature Reviews Drug Discovery. - : Springer Science and Business Media LLC. - 1474-1776 .- 1474-1784. ; 17:5, s. 317-332
-
Journal article (peer-reviewed)abstract
- A large proportion of biomedical research and the development of therapeutics is focused on a small fraction of the human genome. In a strategic effort to map the knowledge gaps around proteins encoded by the human genome and to promote the exploration of currently understudied, but potentially druggable, proteins, the US National Institutes of Health launched the Illuminating the Druggable Genome (IDG) initiative in 2014. In this article, we discuss how the systematic collection and processing of a wide array of genomic, proteomic, chemical and disease-related resource data by the IDG Knowledge Management Center have enabled the development of evidence-based criteria for tracking the target development level (TDL) of human proteins, which indicates a substantial knowledge deficit for approximately one out of three proteins in the human proteome. We then present spotlights on the TDL categories as well as key drug target classes, including G protein-coupled receptors, protein kinases and ion channels, which illustrate the nature of the unexplored opportunities for biomedical research and therapeutic development.
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| 36. |
- Fu, Z. J., et al.
(author)
-
Dyslipidemia in retinal metabolic disorders
- 2019
-
In: Embo Molecular Medicine. - : EMBO. - 1757-4676 .- 1757-4684. ; 11:10
-
Journal article (peer-reviewed)abstract
- The light-sensitive photoreceptors in the retina are extremely metabolically demanding and have the highest density of mitochondria of any cell in the body. Both physiological and pathological retinal vascular growth and regression are controlled by photoreceptor energy demands. It is critical to understand the energy demands of photoreceptors and fuel sources supplying them to understand neurovascular diseases. Retinas are very rich in lipids, which are continuously recycled as lipid-rich photoreceptor outer segments are shed and reformed and dietary intake of lipids modulates retinal lipid composition. Lipids (as well as glucose) are fuel substrates for photoreceptor mitochondria. Dyslipidemia contributes to the development and progression of retinal dysfunction in many eye diseases. Here, we review photoreceptor energy demands with a focus on lipid metabolism in retinal neurovascular disorders.
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| 37. |
- Fu, Z. J., et al.
(author)
-
Targeting Neurovascular Interaction in Retinal Disorders
- 2020
-
In: International Journal of Molecular Sciences. - : MDPI AG. - 1422-0067. ; 21:4
-
Journal article (peer-reviewed)abstract
- The tightly structured neural retina has a unique vascular network comprised of three interconnected plexuses in the inner retina (and choroid for outer retina), which provide oxygen and nutrients to neurons to maintain normal function. Clinical and experimental evidence suggests that neuronal metabolic needs control both normal retinal vascular development and pathological aberrant vascular growth. Particularly, photoreceptors, with the highest density of mitochondria in the body, regulate retinal vascular development by modulating angiogenic and inflammatory factors. Photoreceptor metabolic dysfunction, oxidative stress, and inflammation may cause adaptive but ultimately pathological retinal vascular responses, leading to blindness. Here we focus on the factors involved in neurovascular interactions, which are potential therapeutic targets to decrease energy demand and/or to increase energy production for neovascular retinal disorders.
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| 38. |
- Kadhane, U., et al.
(author)
-
Near-infrared photoabsorption by C-60 dianions in a storage ring
- 2009
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In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 131:1
-
Journal article (peer-reviewed)abstract
- We present a detailed study of the electronic structure and the stability of C-60 dianions in the gas phase. Monoanions were extracted from a plasma source and converted to dianions by electron transfer in a Na vapor cell. The dianions were then stored in an electrostatic ring, and their near-infrared absorption spectrum was measured by observation of laser induced electron detachment. From the time dependence of the detachment after photon absorption, we conclude that the reaction has contributions from both direct electron tunneling to the continuum and vibrationally assisted tunneling after internal conversion. This implies that the height of the Coulomb barrier confining the attached electrons is at least similar to 1.5 eV. For C-60(2-) ions in solution electron spin resonance measurements have indicated a singlet ground state, and from the similarity of the absorption spectra we conclude that also the ground state of isolated C-60(2-) ions is singlet. The observed spectrum corresponds to an electronic transition from a t(1u) lowest unoccupied molecular orbital (LUMO) of C-60 to the t(1g) LUMO+1 level. The electronic levels of the dianion are split due to Jahn-Teller coupling to quadrupole deformations of the molecule, and a main absorption band at 10723 cm(-1) corresponds to a transition between the Jahn-Teller ground states. Also transitions from pseudorotational states with 200 cm(-1) and (probably) 420 cm(-1) excitation are observed. We argue that a very broad absorption band from about 11 500 cm(-1) to 13 500 cm(-1) consists of transitions to so-called cone states, which are Jahn-Teller states on a higher potential-energy surface, stabilized by a pseudorotational angular momentum barrier. A previously observed, high-lying absorption band for C-60(-) may also be a transition to a cone state.
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| 39. |
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| 40. |
- Tomita, S., et al.
(author)
-
Lifetimes of C602- and C702- dianions in a storage ring
- 2006
-
In: J. Chem. Phys.. - : AIP Publishing. - 0021-9606. ; 124
-
Journal article (peer-reviewed)abstract
- C602- and C702- dianions have been produced by electrospray of the monoanions and subsequent electron pickup in a Na vapor cell. The dianions were stored in an electrostatic ring and their decay by electron emission was measured up to 1 s after injection. While C ions are stable on this time scale, except for a small fraction of the ions which have been excited by gas collisions, most of the C ions decay on a millisecond time scale, with a lifetime depending strongly on their internal temperature. The results can be modeled as decay by electron tunneling through a Coulomb barrier, mainly from thermally populated triplet states about 120 meV above a singlet ground state. At times longer than about 100 ms, the absorption of blackbody radiation plays an important role for the decay of initially cold ions. The tunneling rates obtained from the modeling, combined with WKB estimates of the barrier penetration, give a ground-state energy 200±30 meV above the energy of the monoanion plus a free electron and a ground-state lifetime of the order of 20 s.
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| 41. |
- Tomita, Y., et al.
(author)
-
Free fatty acid receptor 4 activation protects against choroidal neovascularization in mice
- 2020
-
In: Angiogenesis. - : Springer Science and Business Media LLC. - 0969-6970 .- 1573-7209. ; 23, s. 385-394
-
Journal article (peer-reviewed)abstract
- To examine whether free fatty acid receptor 4 (FFAR4) activation can protect against choroidal neovascularization (CNV), which is a common cause of blindness, and to elucidate the mechanism underlying the inhibition, we used the mouse model of laser-induced CNV to mimic angiogenic aspects of age-related macular degeneration (AMD). Laser-induced CNV was compared between groups treated with an FFAR4 agonist or vehicle, and between FFAR4 wild-type (Ffar4+/+) and knock out (Ffar4−/−) mice on a C57BL/6J/6N background. The ex vivo choroid-sprouting assay, including primary retinal pigment epithelium (RPE) and choroid, without retina was used to investigate whether FFAR4 affects choroidal angiogenesis. Western blotting for pNF-ĸB/NF-ĸB and qRT-PCR for Il-6, Il-1β, Tnf-α, Vegf, and Nf-ĸb were used to examine the influence of FFAR4 on inflammation, known to influence CNV. RPE isolated from Ffar4+/+ and Ffar4−/− mice were used to assess RPE contribution to inflammation. The FFAR4 agonist suppressed laser-induced CNV in C57BL/6J mice, and CNV increased in Ffar4−/− compared to Ffar4+/+ mice. We showed that the FFAR4 agonist acted through the FFAR4 receptor. The FFAR4 agonist suppressed mRNA expression of inflammation markers (Il-6, Il-1β) via the NF-ĸB pathway in the retina, choroid, RPE complex. The FFAR4 agonist suppressed neovascularization in the choroid-sprouting ex vivo assay and FFAR4 deficiency exacerbated sprouting. Inflammation markers were increased in primary RPE cells of Ffar4−/− mice compared with Ffar4+/+ RPE. In this mouse model, the FFAR4 agonist suppressed CNV, suggesting FFAR4 to be a new molecular target to reduce pathological angiogenesis in CNV. © 2020, Springer Nature B.V.
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| 42. |
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| 43. |
- Fu, Z. J., et al.
(author)
-
Retinal glial remodeling by FGF21 preserves retinal function during photoreceptor degeneration
- 2021
-
In: Iscience. - : Elsevier BV. - 2589-0042. ; 24:4
-
Journal article (peer-reviewed)abstract
- The group of retinal degenerations, retinitis pigmentosa (RP), comprises more than 150 genetic abnormalities affecting photoreceptors. Finding degenerative pathways common to all genetic abnormalities may allow general treatment such as neuroprotection. Neuroprotection may include enhancing the function of cells that directly support photoreceptors, retinal pigment epithelial cells, and Muller glia. Treatment with fibroblast growth factor 21 (FGF21), a neuro-protectant, from postnatal week 4-10, during rod and cone loss in P23H mice (an RP model) with retinal degeneration, preserved photoreceptor function and normalized Muller glial cell morphology. Single-cell transcriptomics of retinal cells showed that FGF21 receptor Fgfr1 was specifically expressed in Muller glia/astrocytes. Of all retinal cells, FGF21 predominantly affected genes in Muller glia/astrocytes with increased expression of axon development and synapse formation pathway genes. Therefore, enhancing retinal glial axon and synapse formation with neurons may preserve retinal function in RP and may suggest a general therapeutic approach for retinal degenerative diseases.
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| 44. |
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| 45. |
- Terenius, Olle, et al.
(author)
-
RNA interference in Lepidoptera : An overview of successful and unsuccessful studies and implications for experimental design
- 2011
-
In: Journal of insect physiology. - : Elsevier BV. - 0022-1910 .- 1879-1611. ; 57:2, s. 231-245
-
Journal article (peer-reviewed)abstract
- Gene silencing through RNA interference (RNAi) has revolutionized the study of gene function, particularly in non-model insects. However, in Lepidoptera (moths and butterflies) RNAi has many times proven to be difficult to achieve. Most of the negative results have been anecdotal and the positive experiments have not been collected in such a way that they are possible to analyze. In this review, we have collected detailed data from more than 150 experiments including all to date published and many unpublished experiments. Despite a large variation in the data, trends that are found are that RNAi is particularly successful in the family Saturniidae and in genes involved in immunity. On the contrary, gene expression in epidermal tissues seems to be most difficult to silence. In addition, gene silencing by feeding dsRNA requires high concentrations for success. Possible causes for the variability of success in RNAi experiments in Lepidoptera are discussed. The review also points to a need to further investigate the mechanism of RNAi in lepidopteran insects and its possible connection to the innate immune response. Our general understanding of RNAi in Lepidoptera will be further aided in the future as our public database at http://insectacentral.org/RNAi will continue to gather information on RNAi experiments.
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| 46. |
- Tomita, Y., et al.
(author)
-
Long-acting FGF21 inhibits retinal vascular leakage in in vivo and in vitro models
- 2020
-
In: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 21:4
-
Journal article (peer-reviewed)abstract
- The aim of the current study was to investigate the impact of long-acting fibroblast growth factor 21 (FGF21) on retinal vascular leakage utilizing machine learning and to clarify the mechanism underlying the protection. To assess the effect on retinal vascular leakage, C57BL/6J mice were pre-treated with long-acting FGF21 analog or vehicle (Phosphate Buffered Saline; PBS) intraperitoneally (i.p.) before induction of retinal vascular leakage with intravitreal injection of mouse (m) vascular endothelial growth factor 164 (VEGF164) or PBS control. Five hours after mVEGF164 injection, we retro-orbitally injected Fluorescein isothiocyanate (FITC) -dextran and quantified fluorescence intensity as a readout of vascular leakage, using the Image Analysis Module with a machine learning algorithm. In FGF21- or vehicle-treated primary human retinal microvascular endothelial cells (HRMECs), cell permeability was induced with human (h) VEGF165 and evaluated using FITC-dextran and trans-endothelial electrical resistance (TEER). Western blots for tight junction markers were performed. Retinal vascular leakage in vivo was reduced in the FGF21 versus vehicle- treated mice. In HRMECs in vitro, FGF21 versus vehicle prevented hVEGF-induced increase in cell permeability, identified with FITC-dextran. FGF21 significantly preserved TEER compared to hVEGF. Taken together, FGF21 regulates permeability through tight junctions; in particular, FGF21 increases Claudin-1 protein levels in hVEGF-induced HRMECs. Long-acting FGF21 may help reduce retinal vascular leakage in retinal disorders and machine learning assessment can help to standardize vascular leakage quantification. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
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| 47. |
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| 48. |
- Concina, B., et al.
(author)
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Delayed ionisation of C-76
- 2006
-
In: INTERNATIONAL JOURNAL OF MASS SPECTROMETRY. - : Elsevier BV. - 1387-3806. ; 252:2, s. 96-99
-
Journal article (peer-reviewed)
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| 49. |
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| 50. |
- Morokuma, Tomoki, et al.
(author)
-
Kiso Supernova Survey (KISS) : Survey strategy
- 2014
-
In: Nippon Tenmon Gakkai obun kenkyu hokoku. - : Oxford University Press (OUP). - 0004-6264. ; 66:6
-
Journal article (peer-reviewed)abstract
- lThe Kiso Supernova Survey (KISS) is a high-cadence optical wide-field supernova (SN) survey. The primary goal of the survey is to catch the very early light of a SN, during the shock breakout phase. Detection of SN shock breakouts combined with multi-band photometry obtained with other facilities would provide detailed physical information on the progenitor stars of SNe. The survey is performed using a 2 degrees.2 x 2 degrees.2 field-of-view instrument on the 1.05-m Kiso Schmidt telescope, the Kiso Wide Field Camera (KWFC). We take a 3-min exposure in g-band once every hour in our survey, reaching magnitude g similar to 20-21. About 100 nights of telescope time per year have been spent on the survey since 2012 April. The number of the shock breakout detections is estimated to be of the order of 1 during our three-year project. This paper summarizes the KISS project including the KWFC observing setup, the survey strategy, the data reduction system, and CBET-reported SNe discovered so far by KISS.
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