| 1. |
- Calabrese, Camilla, et al.
(author)
-
Millimeter Wave Spectrum of the Weakly Bound Complex CH2=CHCN center dot H2O : Structure, Dynamics, and Implications for Astronomical Search
- 2015
-
In: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 119:48, s. 11674-11682
-
Journal article (peer-reviewed)abstract
- The weakly bound 1:1 complex between acrylonitrile (CH2=-CHCN) and water has been characterized spectroscopically in the millimeter wave range (59.6-74.4 GHz) using a Free Jet Absorption Millimeter Wave spectrometer. Precise values of the rotational and quartic centrifugal distortion constants have been obtained from the measured frequencies of the normal and isotopically substituted water moiety (DOH, DOD, (HOH)-O-18). Structural parameters have been estimated from the rotational constants and their differences among isotopologues: the complex has a planar structure with the two subunits held together by a O-H center dot center dot center dot N (2.331(3) angstrom) and a C- H center dot center dot center dot O (2.508(4) angstrom) interaction. The ab initio intermolecular binding energy, obtained at the counterpoise corrected MP2/aug-cc-pVTZ level of calculation, is D-e = 24.4 kJ mol(-1)
|
|
| 2. |
- Adare, A, et al.
(author)
-
Measurements of e+e- pairs from open heavy flavor in p+p and d+A collisions at s NN =200 GeV
- 2017
-
In: Physical Review C. - 2469-9985. ; 96:2
-
Journal article (peer-reviewed)abstract
- We report a measurement of e+e- pairs from semileptonic heavy-flavor decays in p+p collisions at sNN=200 GeV. The e+e- pair yield from bb and cc is separated by exploiting a double differential fit done simultaneously in dielectron invariant mass and pT. We used three different event generators, pythia, mc@nlo, and powheg, to simulate the e+e- spectra from cc and bb production. The data can be well described by all three generators within the detector acceptance. However, when using the generators to extrapolate to 4π, significant differences are observed for the total cross section. These difference are less pronounced for bb than for cc. The same model dependence was observed in already published d+A data. The p+p data are also directly compared with d+A data in mass and pT, and within the statistical accuracy no nuclear modification is seen. © 2017 American Physical Society.
|
|
| 3. |
- Adare, A., et al.
(author)
-
Measurement of higher cumulants of net-charge multiplicity distributions in Au plus Au collisions at root s(NN)=7.7-200 GeV
- 2016
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 93:1
-
Journal article (peer-reviewed)abstract
- We report the measurement of cumulants (C-n,n = 1, ..., 4) of the net-charge distributions measured within pseudorapidity (vertical bar eta vertical bar < 0.35) in Au + Au collisions at root s(NN) = 7.7-200 GeV with the PHENIX experiment at the Relativistic Heavy Ion Collider. The ratios of cumulants (e.g., C-1/C-2, C-3/C-1) of the net-charge distributions, which can be related to volume independent susceptibility ratios, are studied as a function of centrality and energy. These quantities are important to understand the quantum-chromodynamics phase diagram and possible existence of a critical end point. The measured values are very well described by expectation from negative binomial distributions. We do not observe any nonmonotonic behavior in the ratios of the cumulants as a function of collision energy. The measured values of C-1/C-2 and C-3/C-1 can be directly compared to lattice quantum-chromodynamics calculations and thus allow extraction of both the chemical freeze-out temperature and the baryon chemical potential at each center-of-mass energy. The extracted baryon chemical potentials are in excellent agreement with a thermal-statistical analysis model.
|
|
| 4. |
- Adare, A., et al.
(author)
-
Measurements of mass-dependent azimuthal anisotropy in central p + Au, d + Au, and He 3 + Au collisions at sNN =200 GeV
- 2018
-
In: Physical Review C. - 2469-9985. ; 97:6
-
Journal article (peer-reviewed)abstract
- We present measurements of the transverse-momentum dependence of elliptic flow v2 for identified pions and (anti)protons at midrapidity (|η|<0.35), in 0%-5% central p+Au and He3+Au collisions at sNN=200 GeV. When taken together with previously published measurements in d+Au collisions at sNN=200 GeV, the results cover a broad range of small-collision-system multiplicities and intrinsic initial geometries. We observe a clear mass-dependent splitting of v2(pT) in d+Au and He3+Au collisions, just as in large nucleus-nucleus (A+A) collisions, and a smaller splitting in p+Au collisions. Both hydrodynamic and transport model calculations successfully describe the data at low pT (<1.5GeV/c), but fail to describe various features at higher pT. In all systems, the v2 values follow an approximate quark-number scaling as a function of the hadron transverse kinetic energy per constituent quark (KET/nq), which was also seen previously in A+A collisions.
|
|
| 5. |
- Adare, A., et al.
(author)
-
Nuclear-modification factor for open-heavy-flavor production at forward rapidity in Cu plus Cu collisions at root s(NN)=200 GeV
- 2012
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 86:2
-
Journal article (peer-reviewed)abstract
- Background: Heavy-flavor production in p + p collisions is a good test of perturbative-quantum-chromodynamics (pQCD) calculations. Modification of heavy-flavor production in heavy-ion collisions relative to binary-collision scaling from p + p results, quantified with the nuclear-modification factor (R-AA), provides information on both cold-and hot-nuclear-matter effects. Midrapidity heavy-flavor R-AA measurements at the Relativistic Heavy Ion Collider have challenged parton-energy-loss models and resulted in upper limits on the viscosity-entropy ratio that are near the quantum lower bound. Such measurements have not been made in the forward-rapidity region. Purpose: Determine transverse-momentum (p(T)) spectra and the corresponding R-AA for muons from heavy-flavor meson decay in p + p and Cu + Cu collisions at root s(NN) = 200 GeV and y = 1.65. Method: Results are obtained using the semileptonic decay of heavy-flavor mesons into negative muons. The PHENIX muon-arm spectrometers measure the p(T) spectra of inclusive muon candidates. Backgrounds, primarily due to light hadrons, are determined with a Monte Carlo calculation using a set of input hadron distributions tuned to match measured-hadron distributions in the same detector and statistically subtracted. Results: The charm-production cross section in p + p collisions at root s = 200 GeV, integrated over p(T) and in the rapidity range 1.4 < y < 1.9, is found to be d(sigma e (e) over bar)/dy = 0.139 +/- 0.029 (stat)(-0.058)(+0.051) (syst) mb. This result is consistent with a perturbative fixed-order-plus-next-to-leading-log calculation within scale uncertainties and is also consistent with expectations based on the corresponding midrapidity charm-production cross section measured by PHENIX. The R-AA for heavy-flavor muons in Cu + Cu collisions is measured in three centrality bins for 1 < p(T) < 4 GeV/c. Suppression relative to binary-collision scaling (R-AA < 1) increases with centrality. Conclusions: Within experimental and theoretical uncertainties, the measured charm yield in p + p collisions is consistent with state-of-the-art pQCD calculations. Suppression in central Cu + Cu collisions suggests the presence of significant cold-nuclear-matter effects and final-state energy loss.
|
|
| 6. |
- Adare, A., et al.
(author)
-
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.
|
|
| 7. |
- Adare, A., et al.
(author)
-
Centrality-Dependent Modification of Jet-Production Rates in Deuteron-Gold Collisions at sNN =200 GeV
- 2016
-
In: Physical Review Letters. - 0031-9007. ; 116:12
-
Journal article (peer-reviewed)abstract
- Jet production rates are measured in p+p and d+Au collisions at sNN=200 GeV recorded in 2008 with the PHENIX detector at the Relativistic Heavy Ion Collider. Jets are reconstructed using the R=0.3 anti-kt algorithm from energy deposits in the electromagnetic calorimeter and charged tracks in multiwire proportional chambers, and the jet transverse momentum (pT) spectra are corrected for the detector response. Spectra are reported for jets with 12
|
|
| 8. |
- Adare, A., et al.
(author)
-
Cold-Nuclear-Matter Effects on Heavy-Quark Production in d+Au Collisions at root S-NN=200 GeV
- 2012
-
In: Physical Review Letters. - 1079-7114. ; 109:24
-
Journal article (peer-reviewed)abstract
- The PHENIX experiment has measured electrons and positrons at midrapidity from the decays of hadrons containing charm and bottom quarks produced in d + Au and p + p collisions at root S-NN = 200 GeV in the transverse-momentum range 0.85 <= p(T)(e) <= 8.5 GeV/c. In central d + Au collisions, the nuclear modification factor R-dA at 1.5 < p(T) < 5 GeV/c displays evidence of enhancement of these electrons, relative to those produced in p + p collisions, and shows that the mass-dependent Cronin enhancement observed at the Relativistic Heavy Ion Collider extends to the heavy D meson family. A comparison with the neutral-pion data suggests that the difference in cold-nuclear-matter effects on light- and heavy-flavor mesons could contribute to the observed differences between the pi(0) and heavy-flavor-electron nuclear modification factors R-AA. DOI: 10.1103/PhysRevLett.109.242301
|
|
| 9. |
- Adare, A., et al.
(author)
-
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
-
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.
|
|
| 10. |
- Adare, A., et al.
(author)
-
Correlated production of p and (p)over-bar in Au+Au collisions at root s(NN)=200 GeV
- 2007
-
In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 649:5-6, s. 359-369
-
Journal article (peer-reviewed)abstract
- Correlations between p and (p) over bar at transverse momenta typical of enhanced baryon production in Au + Au collisions are reported. The PHENIX experiment has measured same and opposite sign baryon pairs in Au + Au collisions at root s(NN) = 200 GeV. Correlated production of p and p with the trigger particle from the range 2.5 < p(T) < 4.0 GeV/c and the associated particle with 1.8 < p(T) < 2.5 GeV/c is observed to be nearly independent of the centrality of the collisions. Same sign pairs show no correlation at any centrality. The conditional yield of mesons triggered by baryons (and anti-baryons) and mesons in the same p(T) range rises with increasing centrality, except for the most central collisions, where baryons show a significantly smaller number of associated mesons. These data are consistent with a picture in which hard scattered partons produce correlated p and (p) over bar in the p(T) region of the baryon excess. (c) 2007 Elsevier B.V. All rights reserved.
|
|
