Ultranarrow resonance peaks in the transmission and reflection spectra of a photonic crystal cavity with Raman gain

The Raman gain of a probe light in a three-state $\Lambda$-scheme placed into a defect of a one-dimensional photonic crystal is studied theoretically. We show that there exists a pump intensity range, where the transmission and reflection spectra of the probe field exhibit \textit{simultaneously} occurring narrow peaks (resonances) whose position is determined by the Raman resonance. Transmission and reflection coefficients can be larger than unity at pump intensities of order tens of $\mu$W/cm$^{2}$. When the pump intensity is outside this region, the peak in the transmission spectrum turns into a narrow dip. The nature of narrow resonances is attributed to a drastic dispersion of the nonlinear refractive index in the vicinity of the Raman transition, which leads to a significant reduction of the group velocity of the probe wave.Comment: 9 pages, 3 figure

Spatial evolution of short pulses under coherent population trapping

Spatial and temporal evolution is studied of two powerful short laser pulses having different wavelengths and interacting with a dense three-level Lambda-type optical medium under coherent population trapping. A general case of unequal oscillator strengths of the transitions is considered. Durations of the probe pulse and the coupling pulse $T_{1,2}$ ($T_2>T_1$) are assumed to be shorter than any of the relevant atomic relaxation times. We propose analytical and numerical solutions of a self-consistent set of coupled Schr\"{o}dinger equations and reduced wave equations in the adiabatic limit with the account of the first non-adiabatic correction. The adiabaticity criterion is also discussed with the account of the pulse propagation. The dynamics of propagation is found to be strongly dependent on the ratio of the transition oscillator strengths. It is shown that envelopes of the pulses slightly change throughout the medium length at the initial stage of propagation. This distance can be large compared to the one-photon resonant absorption length. Eventually, the probe pulse is completely reemitted into the coupling pulse during propagation. The effect of localization of the atomic coherence has been observed similar to the one predicted by Fleischhauer and Lukin (PRL, {\bf 84}, 5094 (2000).Comment: 16 pages revtex style, 7 EPS figures, accepted to Physical Review

Seasonal movements of veined squid Loligo forbesi in Scottish (UK) waters

In order to protect and sustainably manage fishery resource species, it is essential to understand their movements and habitat use. To detect the hypothesised migration of maturing veined squid Loligo forbesi from the west coast of Scotland (UK) to the North Sea and identify possible inshore-offshore movements, we analysed seasonal, spatial and environmental patterns in abundance and size distribution, based on commercial fishery landings data and trawl survey data from Scottish coastal waters (International Council for the Exploration of the Sea, ICES areas IVa, IVb and VIa). A geographic information system (GIS) was used to build monthly contour maps of abundance. Generalised additive mixed models (GAMM) were used to quantify patterns in size distribution and abundance. In most years, there was no evidence of movement from the West to the East coast of Scotland. Evidence of inshore-offshore movements during the life-cycle of the cohort that recruits in autumn (winter breeders) was found instead. The winter breeding cohort appears to spawn in inshore waters and some evidence suggests that the spawning grounds of the summer breeders are also inshore. Across seasons, higher abundance of L. forbesi can generally be found in the north of Scotland at intermediate water depths and in warmer waters.info:eu-repo/semantics/publishedVersio

ρ0 Photoproduction in AuAu Collisions at √ sNN = 62.4 GeV Measured With the STAR Detector

Vector mesons may be photoproduced in relativistic heavy-ion collisions when a virtual photon emitted by one nucleus scatters from the other nucleus, emerging as a vector meson. The STAR Collaboration has previously presented measurements of coherent ρ0 photoproduction at center of mass energies of 130 GeV and 200 GeV in AuAu collisions. Here, we present a measurement of the cross section at 62.4 GeV; we find that the cross section for coherent ρ0 photoproduction with nuclear breakup is 10.5 ± 1.5 ± 1.6mb at 62.4 GeV. The cross-section ratio between 200 GeV and 62.4 GeV is 4.4 ± 0.6, less than is predicted by most theoretical models. It is, however, proportionally much larger than the previously observed 15% ± 55% increase between 130 GeV and 200 GeV

J/Ѱ polarization in p+p collisions at √s = 200 GeV in STAR

We report on a polarization measurement of inclusive J/Ѱ mesons in the di-electron decay channel at mid-rapidity at 2 \u3c pT \u3c 6 GeV/c in p + p collisions at √s = 200 GeV. Data were taken with the STAR detector at RHIC. The J/Ѱ polarization measurement should help to distinguish between different models of the J/Ѱ production mechanism since they predict different pT dependences of the J/Ѱ polarization. In this analysis, J/Ѱ is studied in the helicity frame. The polarization parameter λθ measured at RHIC becomes smaller towards high pT, indicating more longitudinal J/Ѱ polarization as pT increases. The result is compared with predictions of presently available models

Measurement of the Parity-Violating Longitudinal Single-Spin Asymmetry for W± Boson Production in Polarized Proton-Proton Collisions at √s=500 GeV

We report the first measurement of the parity-violating single-spin asymmetries for midrapidity decay positrons and electrons from W+ and W- boson production in longitudinally polarized proton-proton collisions at √s = 500 GeV by the STAR experiment at RHIC. The measured asymmetries, A(L)(W+) = -0.27± 0.10(stat.) ± 0.02(syst.) ± 0.03(norm.) and A(L)(W-) = 0.14 ± 0.19(stat.) ± 0.02(syst.) ± 0.01(norm.), are consistent with theory predictions, which are large and of opposite sign. These predictions are based on polarized quark and antiquark distribution functions constrained by polarized deep-inelastic scattering measurements

Beam-Energy and System-Size Dependence of Dynamical Net Charge Fluctuations

We present measurements of net charge fluctuations in Au+Au collisions at √sNN=19.6, 62.4, 130, and 200 GeV, Cu+Cu collisions at √sNN=62.4 and 200 GeV, and p+p collisions at √s=200GeV using the dynamical net charge fluctuations measure ν+−,dyn. We observe that the dynamical fluctuations are nonzero at all energies and exhibit a modest dependence on beam energy. A weak system size dependence is also observed. We examine the collision centrality dependence of the net charge fluctuations and find that dynamical net charge fluctuations violate 1/Nch scaling but display approximate 1/Npart scaling. We also study the azimuthal and rapidity dependence of the net charge correlation strength and observe strong dependence on the azimuthal angular range and pseudorapidity widths integrated to measure the correlation

Parton Energy Loss in Heavy-Ion Collisions Via Direct-Photon and Charged-Particle Azimuthal Correlations

Charged-particle spectra associated with direct photon Ydir) and π0 are measured in p+p and Au+Au collisions at center-of-mass energy √sNN=200 GeV with the STAR detector at the Relativistic Heavy Ion Collider. A shower-shape analysis is used to partially discriminate between Ydirand π0. Assuming no associated charged particles in the γdir direction (near side) and small contribution from fragmentation photons (Yfrag), the associated charged-particle yields opposite to Ydir(away side) are extracted. In central Au+Au collisions, the charged-particle yields at midrapidity (|η|\u3c1) and high transverse momentum (3 \u3c PTassoc \u3c 16 GeV/c) associated with γdir and π0 (|η|\u3c0.9, 8 \u3c PTtrig \u3c16 GeV/c) are suppressed by a factor of 3–5 compared with p+p collisions. The observed suppression of the associated charged particles is similar for Ydir and π0 and independent of the γdirenergy within uncertainties. These measurements indicate that, in the kinematic range covered and within our current experimental uncertainties, the parton energy loss shows no sensitivity to the parton initial energy, path length, or color charge

Single Spin Asymmetry AN in Polarized Proton–Proton Elastic Scattering at √s = 200 GeV

We report a high precision measurement of the transverse single spin asymmetry AN at the center of mass energy √s = 200 GeV in elastic proton–proton scattering by the STAR experiment at RHIC. The AN was measured in the four-momentum transfer squared t range 0.003 ⩽ | t | ⩽ 0.035 ( GeV / c ) 2 , the region of a significant interference between the electromagnetic and hadronic scattering amplitudes. The measured values of AN and its t-dependence are consistent with a vanishing hadronic spin-flip amplitude, thus providing strong constraints on the ratio of the single spin-flip to the non-flip amplitudes. Since the hadronic amplitude is dominated by the Pomeron amplitude at this √s, we conclude that this measurement addresses the question about the presence of a hadronic spin flip due to the Pomeron exchange in polarized proton–proton elastic scattering

\u3cem\u3eJ\u3c/em\u3e/\u3cem\u3eψ\u3c/em\u3e Production at Low \u3cem\u3ep\u3csub\u3eT\u3c/sub\u3e\u3c/em\u3e in Au + Au and Cu + Cu Collisions at √\u3cem\u3e\u3csup\u3eS\u3c/sup\u3eNN\u3c/em\u3e = 200 GeV with the STAR Detector

The J/ψ pT spectrum and nuclear modification factor (RAA) are reported for pT \u3c 5 GeV/c and |y| \u3c 1 from 0% to 60% central Au + Au and Cu + Cu collisions at √SNN = 200 GeV at STAR. A significant suppression of pT-integrated J/ψ production is observed in central Au + Au events. The Cu + Cu data are consistent with no suppression, although the precision is limited by the available statistics. RAA in Au + Au collisions exhibits a strong suppression at low transverse momentum and gradually increases with pT. The data are compared to high-pT STAR results and previously published BNL Relativistic Heavy Ion Collider results. Comparing with model calculations, it is found that the invariant yields at low pT are significantly above hydrodynamic flow predictions but are consistent with models that include color screening and regeneration