On the necessity to include event-by-event fluctuations in experimental evaluation of elliptical flow

Elliptic flow at RHIC is computed event-by-event with NeXSPheRIO. We show that when symmetry of the particle distribution in relation to the reaction plane is assumed, as usually done in the experimental extraction of elliptic flow, there is a disagreement between the true and reconstructed elliptic flows (15-30% for $\eta$=0, 30% for $p_\perp$=0.5 GeV). We suggest a possible way to take into account the asymmetry and get good agreement between these elliptic flows

Antihyperon polarization in high-energy inclusive reactions

We propose a model for the antihyperon polarization in high-energy proton-nucleus inclusive reactions, based on the final-state interactions between the antihyperons and other produced particles (predominantly pions). To formulate this idea, we use the previously obtained low-energy pion-(anti-)hyperon interaction using effective chiral Lagrangians, and a hydrodynamic parametrization of the background matter, which expands and decouples at a certain freezeout temperature.Comment: 17 pages, 10 figure

Event-plane dependent di-hadron correlations with harmonic vnv_n subtraction in a hydrodynamic model

In this work, a hydrodynamic study of the di-hadron azimuthal correlations for the Au+Au collisions at 200 GeV is carried out. The correlations are evaluated using the ZYAM method for the centrality windows as well as the transverse momentum range in accordance with the existing data. Event-plane dependence of the correlation is obtained after the subtraction of contributions from the most dominant harmonic coefficients. In particular, the contribution from the triangular flow, $v_3$, is removed from the proper correlations following the procedure implemented by the STAR collaboration. The resultant structure observed in the correlations was sometimes attributed to the mini-jet dynamics, but the present calculations show that a pure hydrodynamic model gives a reasonable agreement with the main feature of the published data. A brief discussion on the physical content of the present findings is presented.Comment: 9 pages, 2 figure

Fluctuations in Hadronic and Nuclear Collisions

We investigate several fluctuation effects in high-energy hadronic and nuclear collisions through the analysis of different observables. To introduce fluctuations in the initial stage of collisions, we use the Interacting Gluon Model (IGM) modified by the inclusion of the impact parameter. The inelasticity and leading-particle distributions follow directly from this model. The fluctuation effects on rapidity distributions are then studied by using Landau's Hydrodynamic Model in one dimension. To investigate further the effects of the multiplicity fluctuation, we use the Longitudinal Phase-Space Model, with the multiplicity distribution calculated within the hydrodynamic model, and the initial conditions given by the IGM. Forward-backward correlation is obtained in this way.Comment: 22 pages, RevTex, 8 figures (included); Invited paper to the special issue of Foundation of Physics dedicated to Mikio Namiki's 70th. birthda

Avalanche related damage potential - changes of persons and mobile values since the mid-twentieth century, case study Galtür

When determining risk related to natural hazard processes, many studies neglect the investigations of the damage potential or are limited to the assessment of immobile values like buildings. However, persons as well as mobile values form an essential part of the damage potential. Knowledge of the maximum number of exposed persons in an endangered area is of great importance for elaborating evacuation plans and immediate measures in case of catastrophes. In addition, motor vehicles can also be highly damaged, as was shown by the analysis of avalanche events. With the removal of mobile values in time as a preventive measure this kind of damage can be minimised. <P style='line-height: 20px;'> This study presents a method for recording the maximum number of exposed persons and monetarily assessing motor vehicles in the municipality of Galt&#252;r (Tyrol, Austria). Moreover, general developments of the damage potential due to significant socio-economic changes since the mid-twentieth century are pointed out in the study area. The present situation of the maximum number of persons and mobile values in the official avalanche hazard zones of the municipality is described in detail. Information on the number of persons is derived of census data, tourism and employment statistics. During the winter months, a significant increase overlaid by strong short-term fluctuation in the number of persons can be noted. These changes result from a higher demand of tourism related manpower as well as from varying occupancy rates. The number of motor vehicles in endangered areas is closely associated to the number of exposed persons. The potential number of motor vehicles is investigated by means of mapping, statistics on the stock of motor vehicles and the density distribution. Diurnal and seasonal fluctuations of the investigated damage potential are pointed out. The recording of the number of persons and mobile values in endangered areas is vital for any disaster management

Shock propagation and stability in causal dissipative hydrodynamics

We studied the shock propagation and its stability with the causal dissipative hydrodynamics in 1+1 dimensional systems. We show that the presence of the usual viscosity is not enough to stabilize the solution. This problem is solved by introducing an additional viscosity which is related to the coarse-graining scale of the theory.Comment: 14 pages, 16 figure

Fluctuations of the Initial Conditions and the Continuous Emission in Hydrodynamic Description of Two-Pion Interferometry

Within hydrodynamic approach, we study the Bose-Einstein correlation of identical pions by taking into account both event-by-event fluctuating initial conditions and continuous pion emission during the whole development of the hot and dense matter formed in high-energy collisions. Considerable deviations occur, compared to the usual hydro calculations with smooth initial conditions and a sudden freeze-out on a well defined hypersurface. Comparison with data at RHIC shows that, despite rather rough approximation we used here, this description can give account of the $m_T$ dependence of $R_L$ and $R_s$ and improves considerably the one for $R_o$ with respect to the usual version.Comment: 5 pages, 4 figure

The large N limit of M2-branes on Lens spaces

We study the matrix model for N M2-branes wrapping a Lens space L(p,1) = S^3/Z_p. This arises from localization of the partition function of the ABJM theory, and has some novel features compared with the case of a three-sphere, including a sum over flat connections and a potential that depends non-trivially on p. We study the matrix model both numerically and analytically in the large N limit, finding that a certain family of p flat connections give an equal dominant contribution. At large N we find the same eigenvalue distribution for all p, and show that the free energy is simply 1/p times the free energy on a three-sphere, in agreement with gravity dual expectations.Comment: 28 pages, 4 figure

Evaluation des systemes d’irrigation des cultures de Abelmoschus esculentus (L.) Moench et Cucumis sativus L. sur le site maraîcher de Bougoum, au 5ème arrondissement de Niamey (niger, Afrique de l’Ouest)

Les rendements de deux espèces de cultures maraîchères, à savoir le gombo (Abelmoschus esculentus) et le concombre (Cucumis sativus) ont été évalués selon quatre systèmes d’irrigation sur les sites maraîchers de Bougoum, à l’Ouest du Niger. Ainsi, les rendements moyens (T/ha) de la production du gombo par le système Traditionnel est le plus élevé (15,1 T/ha), suivi du système Jardin Tropical Africain (14,72 T/ha), ensuite par le système Goutte à Goutte (14,21 T/ha), puis le système par aspersion (8,38 T/ha). Ce dernier est le seul à ne pas donner un résultat comparable à ceux obtenus par la fédération des coopératives maraîchères du Niger (FCMN) qui est de l’ordre de 14 à 30 T/ha. Pour la culture du concombre, l’aspersion et le traditionnel ont donné des résultats satisfaisants, comparables aux résultats de la FCMN (30 à 80 T/ha) et dont les valeurs respectives sont 47,13 T/ha et 47,43 T/ha. Pour les systèmes Goutte à Goutte on obtient des faibles résultats qui pourraient être expliqués d’une part par les dégâts des vers de terre qui ont vidé le contenu des graines semées et d’autres parts l’effet de la chaleur sur les plantules.Mots-clés: irrigation, maraîchage, Bougoum, Niger, Afrique de l’OuestEnglish Title: Evaluation of irrigation systems Abelmoschus esculentus (L.) Moench and Cucumis sativus L. cultures on site gardener from Bougoum, the 5th district of Niamey niger West AfricaEnglish AbstractYields of two species of vegetable crops, namely okra (Abelmoschus esculentus) and cucumber (Cucumis sativus) were investigated using four irrigation systems on the vegetable production sites of Bougoum, west of Niger. Thus, average yields (t/ha) production okra by the traditional system is found to be the highest (15.1 t/ha), followed by the system Jardin Tropical Africa (14.72 t/ha), followed by the Drip system (14.21 t/ha), and the sprinkler system (8.38 t/ha). The latter yielded results that cannot be compared to those obtained by the Federation of vegetable production cooperatives in Niger (FVPCN), which is estimated from 14 to 30 t/ha. Regarding the cultivation of cucumber, sprinkling and traditional yielded respectively 47.13 t/ha and 47.43 t/ha which are satisfactory results comparable to the results of FVPCN (from 30 to 80 t/ha. Finally, the Drip Drip systems yielded poor results, which could be explained not only by the damage of earthworms emptying the contents of the sown seeds, but also the heat effect on seedlings.Keywords: irrigation, vegetable production, Bougoum, Niger, West Afric