Demonstration of the temporal matter-wave Talbot effect for trapped matter waves

We demonstrate the temporal Talbot effect for trapped matter waves using ultracold atoms in an optical lattice. We investigate the phase evolution of an array of essentially non-interacting matter waves and observe matter-wave collapse and revival in the form of a Talbot interference pattern. By using long expansion times, we image momentum space with sub-recoil resolution, allowing us to observe fractional Talbot fringes up to 10th order.Comment: 17 pages, 7 figure

Kaon Production and Kaon to Pion Ratio in Au+Au Collisions at \snn=130 GeV

Mid-rapidity transverse mass spectra and multiplicity densities of charged and neutral kaons are reported for Au+Au collisions at \snn=130 GeV at RHIC. The spectra are exponential in transverse mass, with an inverse slope of about 280 MeV in central collisions. The multiplicity densities for these particles scale with the negative hadron pseudo-rapidity density. The charged kaon to pion ratios are $K^+/\pi^- = 0.161 \pm 0.002 {\rm (stat)} \pm 0.024 {\rm (syst)}$ and $K^-/\pi^- = 0.146 \pm 0.002 {\rm (stat)} \pm 0.022 {\rm (syst)}$ for the most central collisions. The $K^+/\pi^-$ ratio is lower than the same ratio observed at the SPS while the $K^-/\pi^-$ is higher than the SPS result. Both ratios are enhanced by about 50% relative to p+p and $\bar{\rm p}$+p collision data at similar energies.Comment: 6 pages, 3 figures, 1 tabl

Phi meson production in Au+Au and p+p collisions at sqrt (s)=200 GeV

We report the STAR measurement of Phi meson production in Au+Au and p+p collisions at sqrt (s)=200 GeV. Using the event mixing technique, the Phi spectra and yields are obtained at mid-rapidity for five centrality bins in Au+Au collisions and for non-singly-diffractive p+p collisions. It is found that the Phi transverse momentum distributions from Au+Au collisions are better fitted with a single-exponential while the p+p spectrum is better described by a double-exponential distribution. The measured nuclear modification factors indicate that Phi production in central Au+Au collisions is suppressed relative to peripheral collisions when scaled by the number of binary collisions. The systematics of versus centrality and the constant Phi/K- ratio versus beam species, centrality, and collision energy rule out kaon coalescence as the dominant mechanism for Phi production.Comment: 6 pages, 3 figures, submitted to Phys. Rev. Let

Azimuthal anisotropy at RHIC: the first and fourth harmonics

We report the first observations of the first harmonic (directed flow, v_1), and the fourth harmonic (v_4), in the azimuthal distribution of particles with respect to the reaction plane in Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC). Both measurements were done taking advantage of the large elliptic flow (v_2) generated at RHIC. From the correlation of v_2 with v_1 it is determined that v_2 is positive, or {\it in-plane}. The integrated v_4 is about a factor of 10 smaller than v_2. For the sixth (v_6) and eighth (v_8) harmonics upper limits on the magnitudes are reported.Comment: 6 pages with 3 figures, as accepted for Phys. Rev. Letters The data tables are at http://www.star.bnl.gov/central/publications/pubDetail.php?id=3

Mid-rapidity anti-proton to proton ratio from Au+Au collisions at sNN=130 \sqrt{s_{NN}} = 130 GeV

We report results on the ratio of mid-rapidity anti-proton to proton yields in Au+Au collisions at \rts = 130 GeV per nucleon pair as measured by the STAR experiment at RHIC. Within the rapidity and transverse momentum range of $|y|<0.5$ and 0.4 $<p_t<$ 1.0 GeV/$c$, the ratio is essentially independent of either transverse momentum or rapidity, with an average of $0.65\pm 0.01_{\rm (stat.)} \pm 0.07_{\rm (syst.)}$ for minimum bias collisions. Within errors, no strong centrality dependence is observed. The results indicate that at this RHIC energy, although the $p$-\pb pair production becomes important at mid-rapidity, a significant excess of baryons over anti-baryons is still present.Comment: 5 pages, 3 figures, accepted by Phys. Rev. Let

Strange anti-particle to particle ratios at mid-rapidity in sqrt(s_NN)= 130 GeV Au+Au Collisions

Values of the ratios in the mid-rapidity yields of anti-Lambda/Lambda = 0.71 +/- 0.01(stat.) +/- 0.04(sys.), anti-Xi+/Xi- = 0.83 +/- 0.04(stat.) +/- 0.05 (sys.), anti-Omega+/Omega- = 0.95 +/- 0.15(stat) +/- 0.05(sys.) and K+/K- 1.092 +/- 0.023(combined) were obtained in central sqrt(s_NN) = 130 GeV Au+Au collisions using the STAR detector. The ratios indicate that a fraction of the net-baryon number from the initial system is present in the excess of hyperons over anti-hyperons at mid-rapidity. The trend in the progression of the baryon ratios, with increasing strange quark content, is similar to that observed in heavy-ion collisions at lower energies. The value of these ratios may be related to the charged kaon ratio in the framework of simple quark-counting and thermal models.Comment: 6 pages, 3 figures, revtex4, now accepted by Physics Letters B. All figures improved for clarity, fig. 2 now has kaon ratio separated by technique, fig. 3 now has additional other RHIC data points. Minor clarifications in text in response to referee comments. Updated ref

ρ\u3csup\u3e0\u3c/sup\u3e production and possible modification in Au + Au and p + p collisions at √s\u3csub\u3eNN\u3c/sub\u3e = 200 GeV

We report results on ρ(770)0→π+π− production at midrapidity in p+p and peripheral Au+Au collisions at √sNN=200  GeV. This is the first direct measurement of ρ(770)0→π+π− in heavy-ion collisions. The measured ρ0 peak in the invariant mass distribution is shifted by ∼40  MeV/c2 in minimum bias p+p interactions and ∼70  MeV/c2 in peripheral Au+Au collisions. The ρ0 mass shift is dependent on transverse momentum and multiplicity. The modification of the ρ0 meson mass, width, and shape due to phase space and dynamical effects are discussed

Distributions of Charged Hadrons Associated with High Transverse Momentum Particles in pp and Au+Au Collisions at √s\u3csub\u3eNN\u3c/sub\u3e = 200 GeV

Charged hadrons in 0.15⊥\u3c4  GeV/c associated with particles of ptrig⊥\u3e4  GeV/c are reconstructed in pp and Au+Au collisions at √sNN=200  GeV. The associated multiplicity and p⊥magnitude sum are found to increase from pp to central Au+Au collisions. The associated p⊥distributions, while similar in shape on the nearside, are significantly softened on the awayside in central Au+Au relative to pp and not much harder than that of inclusive hadrons. The results, consistent with jet quenching, suggest that the awayside fragments approach equilibration with the medium traversed

Event-wise ⟨p\u3csub\u3et\u3c/sub\u3e⟩ fluctuations in Au-Au collisions at √s\u3csub\u3eNN\u3c/sub\u3e = 130 GeV

We present the first large-acceptance measurement of event-wise mean transverse momentum ⟨pt⟩ fluctuations for Au-Au collisions at nucleon-nucleon center-of-momentum collision energy √sNN = 130 GeV. The observed nonstatistical ⟨pt⟩ fluctuations substantially exceed in magnitude fluctuations expected from the finite number of particles produced in a typical collision. The r.m.s. fractional width excess of the event-wise ⟨pt⟩ distribution is 13.7±0.1(stat) ±1.3(syst)% relative to a statistical reference, for the 15% most-central collisions and for charged hadrons within pseudorapidity range |η|c. The width excess varies smoothly but nonmonotonically with collision centrality and does not display rapid changes with centrality which might indicate the presence of critical fluctuations. The reported ⟨pt⟩ fluctuation excess is qualitatively larger than those observed at lower energies and differs markedly from theoretical expectations. Contributions to ⟨pt⟩ fluctuations from semihard parton scattering in the initial state and dissipation in the bulk colored medium are discussed

Сотрудничество Узбекистана и России как стабилизирующий фактор на евразийском пространстве

In the article the relations of Uzbekistan and Russia are examined in the context of making integration process more active in Eurasia based on the example of EAEU and SCO, proceeding in the period of increased turbulence of world system in 2014-2016, the aggravations of Russian relations with the West in connection with the introduction of anti-Russian sanctions and reorientation of Russian foreign economic policy to the East. The authors examine the development of Uzbek - Russian relations on the wide historical background in the light of interests of both countries, possibilities of increasing their competitive ability under the conditions of strengthening the crisis phenomena in the contemporary world as a whole, and on the Eurasian economic space, in particular. The association of the efforts of the two countries in the fight against international terrorism - one of the most serious calls of the present, participation in the solution of the vital problems of international safety on the continent within the framework of integrated associations could give additional political weight to both countries. The ability of Uzbekistan and Russia to search for and to find compromises in the process of regulating debatable questions of political and economic interactions is shown. In the article the attention is paid to the unrealized possibilities of the Uzbek - Russian relations, which are considered as the possible factor of the development of integration process in Eurasia. The authors consider the absence of any other alternative to further positive development of relations between Russia and Uzbekistan and to strengthening the many-sided contacts between them, which sources were placed in the distant past. The idea is defended about the fact that joining EAEU could bring essential political and economic dividends to Uzbekistan. Through the economic collaboration with Uzbekistan Russia can have the specific effect on its integrative policy.Уход президента Узбекистана И. Каримова побудил авторов статьи предпринять попытку анализа того наследия, которое он оставил после себя как крупный политический деятель современности, в том числе в контексте интеграционных процессов на постсоветском пространстве. В статье рассматриваются отношения Узбекистана и России в контексте активизации интеграционных процессов в Евразии на примере ЕАЭС и ШОС, происходящих в период повышенной турбулентности мировой системы в 2014-2016 гг., обострения отношений России с Западом в связи с введением антироссийских санкций и переориентации российской внешнеэкономической политики на Восток. Авторы рассматривают развитие узбекско-российских отношений на широком историческом фоне в свете интересов обеих стран, возможностей повышения их конкурентоспособности в условиях усиления кризисных явлений в современном мире в целом и на евразийском экономическом пространстве, в частности. Объединение усилий двух стран в борьбе с международным терроризмом - одним из наиболее серьезных вызовов современности, участие в решении актуальных проблем международной безопасности на континенте в рамках интеграционных объединений могли бы придать дополнительный политический вес обеим странам. Показана способность Узбекистана и России искать и находить компромиссы в процессе урегулирования спорных вопросов политического и экономического взаимодействия. В статье обращается внимание на нереализованные возможности узбекско-российских отношений, которые рассматриваются как возможный фактор развития интеграционных процессов в Евразии