1. |
- 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
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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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2. |
- 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
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 91:3
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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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3. |
- Adare, A., et al.
(author)
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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
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 87:4
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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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4. |
- Adare, A., et al.
(author)
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Low-mass vector-meson production at forward rapidity in p plus p collisions at root s=200 GeV
- 2014
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In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 90:5
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Journal article (peer-reviewed)abstract
- The PHENIX experiment at the Relativistic Heavy Ion Collider has measured low-mass vector-meson ,omega, rho, and phi, production through the dimuon decay channel at forward rapidity (1.2 < vertical bar y vertical bar < 2.2) in p + p collisions at root s = 200 GeV. The differential cross sections for these mesons are measured as a function of both p(T) and rapidity. We also report the integrated differential cross sections over 1 < p(T) < 7 GeV/c and 1.2 < vertical bar y vertical bar < 2.2: d sigma/dy(omega + rho rho -> mu mu) = 80 +/- 6(stat) +/- 12(syst)nb and d sigma/dy(phi -> mu mu) = 27 +/- 3(stat) +/- 4(syst)nb. These results are compared with midrapidity measurements and calculations.
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5. |
- Adare, A., et al.
(author)
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Cold-Nuclear-Matter Effects on Heavy-Quark Production at Forward and Backward Rapidity in d + Au Collisions at root s(NN) = GeV
- 2014
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In: Physical Review Letters. - 1079-7114. ; 112:25
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Journal article (peer-reviewed)abstract
- The PHENIX experiment has measured open heavy-flavor production via semileptonic decay over the transverse momentum range 1 < p(T) < 6 GeV/c at forward and backward rapidity (1.4 < vertical bar y vertical bar < 2.0) in d + Au and p + p collisions at root s(NN) = 200 GeV. In central d + Au collisions, relative to the yield in p + p collisions scaled by the number of binary nucleon-nucleon collisions, a suppression is observed at forward rapidity (in the d-going direction) and an enhancement at backward rapidity (in the Au-going direction). Predictions using nuclear-modified-parton-distribution functions, even with additional nuclear-p(T) broadening, cannot simultaneously reproduce the data at both rapidity ranges, which implies that these models are incomplete and suggests the possible importance of final-state interactions in the asymmetric d + Au collision system. These results can be used to probe cold-nuclear-matter effects, which may significantly affect heavy-quark production, in addition to helping constrain the magnitude of charmonia-breakup effects in nuclear matter.
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6. |
- Adare, A, et al.
(author)
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Measurement of Long-Range Angular Correlation and Quadrupole Anisotropy of Pions and (Anti)Protons in Central d+Au Collisions at sqrt[s_{NN}]=200 GeV.
- 2015
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In: Physical Review Letters. - 1079-7114. ; 114:19
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Journal article (peer-reviewed)abstract
- We present azimuthal angular correlations between charged hadrons and energy deposited in calorimeter towers in central d+Au and minimum bias p+p collisions at sqrt[s_{NN}]=200 GeV. The charged hadron is measured at midrapidity |η|<0.35, and the energy is measured at large rapidity (-3.7<η<-3.1, Au-going direction). An enhanced near-side angular correlation across |Δη|>2.75 is observed in d+Au collisions. Using the event plane method applied to the Au-going energy distribution, we extract the anisotropy strength v_{2} for inclusive charged hadrons at midrapidity up to p_{T}=4.5 GeV/c. We also present the measurement of v_{2} for identified π^{±} and (anti)protons in central d+Au collisions, and observe a mass-ordering pattern similar to that seen in heavy-ion collisions. These results are compared with viscous hydrodynamic calculations and measurements from p+Pb at sqrt[s_{NN}]=5.02 TeV. The magnitude of the mass ordering in d+Au is found to be smaller than that in p+Pb collisions, which may indicate smaller radial flow in lower energy d+Au collisions.
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7. |
- Adare, A., et al.
(author)
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Charged-pion cross sections and double-helicity asymmetries in polarized p plus p collisions at root s=200 GeV
- 2015
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In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 91:3
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Journal article (peer-reviewed)abstract
- We present midrapidity charged-pion invariant cross sections, the ratio of the pi(-) to pi(+) cross sections and the charge-separated double-spin asymmetries in polarized p + p collisions at root s = p + 200 GeV. While the cross section measurements are consistent within the errors of next-to-leading-order (NLO) perturbative quantum chromodynamics predictions (pQCD), the same calculations overestimate the ratio of the charged-pion cross sections. This discrepancy arises from the cancellation of the substantial systematic errors associated with the NLO-pQCD predictions in the ratio and highlights the constraints these data will place on flavor-dependent pion fragmentation functions. The charge-separated pion asymmetries presented here sample an x range of similar to 0.03-0.16 and provide unique information on the sign of the gluon-helicity distribution.
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8. |
- Adare, A., et al.
(author)
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Cross Section and Parity-Violating Spin Asymmetries of W-+/- Boson Production in Polarized p plus p Collisions at root s=500 Gev
- 2011
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In: Physical Review Letters. - 1079-7114. ; 106:6
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Journal article (peer-reviewed)abstract
- Large parity-violating longitudinal single-spin asymmetries A(L)(e+) = 0.86(-0.14)(+0.30) and Ae(L)(e-) = 0.88(-0.71)(+0.12) are observed for inclusive high transverse momentum electrons and positrons in polarized p + p collisions at a center-of-mass energy of root s = 500 GeV with the PHENIX detector at RHIC. These e(+/-) come mainly from the decay of W-+/- and Z(0) bosons, and their asymmetries directly demonstrate parity violation in the couplings of the W-+/- to the light quarks. The observed electron and positron yields were used to estimate W-+/- boson production cross sections for the e(+/-) channels of sigma(pp -> W+X) X BR(W+ -> e(+) nu(e)) = 144.1 +/- 21.2(stat)(-10.3)(+3.4)(syst) +/- 21.6(norm) pb, and sigma(pp -> W-X) X BR(W- -> e(-) (nu) over bar (e)) = 3.17 +/- 12.1(stat)(-8.2)(+10.1)(syst) +/- 4.8(norm) pb.
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9. |
- Adare, A., et al.
(author)
-
Double-spin asymmetry of electrons from heavy-flavor decays in p plus p collisions at root s=200 GeV
- 2013
-
In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 87:1
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Journal article (peer-reviewed)abstract
- We report on the first measurement of the double-spin asymmetry, A(LL), of electrons from the decays of hadrons containing heavy flavor in longitudinally polarized p + p collisions at root s = 200 GeV for p(T) = 0.5 to 3.0 GeV/c. The asymmetry was measured at midrapidity (vertical bar eta vertical bar < 0.35) with the PHENIX detector at the Relativistic Heavy Ion Collider. The measured asymmetries are consistent with zero within the statistical errors. We obtained a constraint for the polarized gluon distribution in the proton of vertical bar Delta g/g(log(10)(x) = -1.6(-0.4)(+0.5), mu = m(T)(c)vertical bar(2) < 0.030 (1 sigma) based on a leading-order perturbative quantum chromodynamics model, using the measured asymmetry. DOI: 10.1103/PhysRevD.87.012011
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10. |
- Adare, A., et al.
(author)
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Inclusive double-helicity asymmetries in neutral-pion and eta-meson production in + collisions at root s=200 GeV
- 2014
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In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 90:1
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Journal article (peer-reviewed)abstract
- Results are presented from data recorded in 2009 by the PHENIX experiment at the Relativistic Heavy Ion Collider for the double-longitudinal spin asymmetry, A(LL), for pi(0) and eta production in root s = 200 GeV polarized p + p collisions. Comparison of the pi(0) results with different theory expectations based on fits of other published data showed a preference for small positive values of gluon polarization, Delta G, in the proton in the probed Bjorken x range. The effect of adding the new 2009 pi(0) data to a recent global analysis of polarized scattering data is also shown, resulting in a best fit Delta G(DSSV)([0.05,0.2]) = 0.06(-0.15)(+0.11) in the range 0.05 < x < 0.2, with the uncertainty at Delta chi(2) = 9 when considering only statistical experimental uncertainties. Shifting the PHENIX data points by their systematic uncertainty leads to a variation of the best-fit value of Delta G(DSSV)([0.05,0.2]) between 0.02 and 0.12, demonstrating the need for full treatment of the experimental systematic uncertainties in future global analyses.
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11. |
- Sugai, H., et al.
(author)
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Updated Design of the CMB Polarization Experiment Satellite LiteBIRD
- 2020
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In: Journal of Low Temperature Physics. - : Springer Science and Business Media LLC. - 0022-2291 .- 1573-7357. ; 199:3-4, s. 1107-1117
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Journal article (peer-reviewed)abstract
- Recent developments of transition-edge sensors (TESs), based on extensive experience in ground-based experiments, have been making the sensor techniques mature enough for their application on future satellite cosmic microwave background (CMB) polarization experiments. LiteBIRD is in the most advanced phase among such future satellites, targeting its launch in Japanese Fiscal Year 2027 (2027FY) with JAXA's H3 rocket. It will accommodate more than 4000 TESs in focal planes of reflective low-frequency and refractive medium-and-high-frequency telescopes in order to detect a signature imprinted on the CMB by the primordial gravitational waves predicted in cosmic inflation. The total wide frequency coverage between 34 and 448 GHz enables us to extract such weak spiral polarization patterns through the precise subtraction of our Galaxy's foreground emission by using spectral differences among CMB and foreground signals. Telescopes are cooled down to 5 K for suppressing thermal noise and contain polarization modulators with transmissive half-wave plates at individual apertures for separating sky polarization signals from artificial polarization and for mitigating from instrumental 1/f noise. Passive cooling by using V-grooves supports active cooling with mechanical coolers as well as adiabatic demagnetization refrigerators. Sky observations from the second Sun-Earth Lagrangian point, L2, are planned for 3 years. An international collaboration between Japan, the USA, Canada, and Europe is sharing various roles. In May 2019, the Institute of Space and Astronautical Science, JAXA, selected LiteBIRD as the strategic large mission No. 2.
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12. |
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13. |
- Elsik, Christine G., et al.
(author)
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The Genome Sequence of Taurine Cattle : A Window to Ruminant Biology and Evolution
- 2009
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 324:5926, s. 522-528
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Journal article (peer-reviewed)abstract
- To understand the biology and evolution of ruminants, the cattle genome was sequenced to about sevenfold coverage. The cattle genome contains a minimum of 22,000 genes, with a core set of 14,345 orthologs shared among seven mammalian species of which 1217 are absent or undetected in noneutherian (marsupial or monotreme) genomes. Cattle-specific evolutionary breakpoint regions in chromosomes have a higher density of segmental duplications, enrichment of repetitive elements, and species-specific variations in genes associated with lactation and immune responsiveness. Genes involved in metabolism are generally highly conserved, although five metabolic genes are deleted or extensively diverged from their human orthologs. The cattle genome sequence thus provides a resource for understanding mammalian evolution and accelerating livestock genetic improvement for milk and meat production.
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14. |
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15. |
- Homma, K., et al.
(author)
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COMBINED LASER GAMMA EXPERIMENTS AT ELI-NP
- 2016
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In: Romanian Reports on Physics. - 1221-1451 .- 1841-8759. ; 68, s. S233-S274
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Journal article (peer-reviewed)abstract
- We propose experiments in the E7 and E4 experimental areas at ELI-NP to tackle problems of fundamental physics, taking advantage of the unique configuration and characteristics of the new research infrastructure to be constructed in Magurele, Romania. The experimental setups proposed follow a gradual approach from the point of view of complexity, from the "Day 1" experiments to experiments for which the prerequisites include results from the previously performed ones. In addition, there are two generic Research and Development tasks proposed in this Technical Design Report (TDR), related to the development of a detection system, Gamma Polari-Calorimeter (GPC), commonly applicable to energy measurements for electrons, positrons and gamma-rays above the 0.1 GeV energy scale and the preparatory tests for laser plasma acceleration of electrons up to necessary energies 210 MeV, 2.5 GeV and 5 GeV for the later stage experiments, respectively. In this paper we particularly focus on possible "Day-1" topics and briefly mention the future extensions foreseen.
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16. |
- Morokuma, Tomoki, et al.
(author)
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Subaru FOCAS Spectroscopic Observations of High-Redshift Supernovae
- 2010
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In: Nippon Tenmon Gakkai obun kenkyu hokoku. - 0004-6264. ; 62:1, s. 19-37
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Journal article (peer-reviewed)abstract
- We present spectra of high-redshift supernovae (SNe) that were taken with the Subaru low-resolution optical spectrograph, FOCAS. These SNe were found in SN surveys with Suprime-Cam on Subaru, the CFH12k camera on the Canada-France-Hawaii Telescope, and the Advanced Camera for Surveys on the Hubble Space Telescope. These SN surveys specifically targeted z > 1 Type la supernovae (SNe Ia). From the spectra of 39 candidates, we obtained redshifts for 32 candidates and spectroscopically identified 7 active candidates as probable SNe Ia, including one at z = 1.35, which is the most distant SN la to be spectroscopically confirmed with a ground-based telescope. An additional 4 candidates were identified as likely SNe la from the spectrophotometric properties of their host galaxies. Seven candidates are not SNe la, either being SNe of another type or active galactic nuclei. When SNe la were observed within one week of the maximum light, we found that we could spectroscopically identify most of them up to z = 1.1. Beyond this redshift, very few candidates were spectroscopically identified as SNe Ia. The current generation of super red-sensitive, fringe-free CCDs will push this redshift limit higher.
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17. |
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