The Experts below are selected from a list of 261 Experts worldwide ranked by ideXlab platform
Kirill Tuchin - One of the best experts on this subject based on the ideXlab platform.
-
Gluon Saturation effects on the Color singlet J/ψ production in high energy dA and AA collisions
Nuclear Physics A, 2013Co-Authors: Kirill TuchinAbstract:Abstract We discuss the gluon Saturation/Color glass condensate effects on J / ψ production in high energy pA and AA collisions. We report the results of numerical calculations of the corresponding nuclear modification factors. We found a good agreement between our calculations and the experimental data on J / ψ production in pA collisions. We also observe that cold nuclear modification effects alone cannot describe the data on J / ψ production in AA collisions. Our numerical calculations indicate that the discrepancy arises mostly from the higher p T ʼs. Additional final state suppression (at RHIC) and enhancement (at LHC) mechanisms are required to explain the experimental data.
-
gluon Saturation effects on the Color singlet j ψ production in high energy da and aa collisions
Physics Letters B, 2012Co-Authors: Fabio Dominguez, Dmitri E. Kharzeev, Eugene Levin, A H Mueller, Kirill TuchinAbstract:Abstract We derive the formulae for the cross section of J / ψ production in high energy pA and AA collisions taking into account the gluon Saturation/Color glass condensate effects. We then perform the numerical calculations of the corresponding nuclear modification factors and find a good agreement between our calculations and the experimental data on J / ψ production in pA collisions. We also observe that cold nuclear modification effects alone cannot describe the data on J / ψ production in AA collisions. Additional final state suppression (at RHIC) and enhancement (at LHC) mechanisms are required to explain the experimental observations.
-
Gluon Saturation effects on the Color singlet J/ψ production in high energy dA and AA collisions
Physics Letters B, 2012Co-Authors: Fabio Dominguez, Alfred H. Mueller, Dmitri E. Kharzeev, Eugene Levin, Kirill TuchinAbstract:Abstract We derive the formulae for the cross section of J / ψ production in high energy pA and AA collisions taking into account the gluon Saturation/Color glass condensate effects. We then perform the numerical calculations of the corresponding nuclear modification factors and find a good agreement between our calculations and the experimental data on J / ψ production in pA collisions. We also observe that cold nuclear modification effects alone cannot describe the data on J / ψ production in AA collisions. Additional final state suppression (at RHIC) and enhancement (at LHC) mechanisms are required to explain the experimental observations.
-
Diffractive hadron production in deep inelastic scattering off heavy nuclei and gluon Saturation
Physical Review D, 2011Co-Authors: Kirill TuchinAbstract:We calculate the cross section for diffractive hadron production in deep inelastic scattering off heavy nuclei in the framework of gluon Saturation/Color glass condensate. We analyze the kinematic region of the future Electron-Ion Collider. We argue that coherent and incoherent diffractive channels are very sensitive to the structure of the nuclear matter at low x. This expresses itself in a characteristic dependence of the cross sections on rapidity and transverse momentum of the produced hadron and on the nuclear weight. We also discuss dependence on the scattering angle and argue that both coherent and incoherent cross sections may be within experimental reach at Electron-Ion Collider.
Yuri V Kovchegov - One of the best experts on this subject based on the ideXlab platform.
-
How classical gluon fields generate odd azimuthal harmonics for the two-gluon correlation function in high-energy collisions
Physical Review D, 2018Co-Authors: Yuri V Kovchegov, Vladimir SkokovAbstract:Long range rapidity correlations observed in high energy collisions may be explained within the Saturation/Color-Glass-Condensate formalism. However, previous work only accounts for even azimuthal harmonic correlations. In this paper the authors confirm that odd harmonics can arise from Saturation corrections via explicit analytic calculations.
-
when gluons go odd how classical gluon fields generate odd azimuthal harmonics for the two gluon correlation function in high energy collisions
arXiv: High Energy Physics - Phenomenology, 2018Co-Authors: Yuri V Kovchegov, Vladimir SkokovAbstract:We show that, in the Saturation/Color Glass Condensate framework, odd azimuthal harmonics of the two-gluon correlation function with a long-range separation in rapidity are generated by the higher-order Saturation corrections in the interactions with the projectile and the target. At the very least, the odd harmonics require three scatterings in the projectile and three scatterings in the target. We derive the leading-order expression for the two-gluon production cross section which generates odd harmonics: the expression includes all-order interactions with the target and three interactions with the projectile. We evaluate the obtained expression both analytically and numerically, confirming that the odd-harmonics contribution to the two-gluon production in the Saturation framework is non-zero.
-
two gluon correlations in heavy light ion collisions energy and geometry dependence ir divergences and k_t factorization
Nuclear Physics, 2014Co-Authors: Yuri V Kovchegov, Douglas E. WertepnyAbstract:Abstract We study the properties of the cross section for two-gluon production in heavy–light ion collisions derived in our previous paper [1] in the Saturation/Color Glass Condensate framework. Concentrating on the energy and geometry dependence of the corresponding correlation functions we find that the two-gluon correlator is a much slower function of the center-of-mass energy than the one- and two-gluon production cross sections. The geometry dependence of the correlation function leads to stronger azimuthal near- and away-side correlations in the tip-on-tip U + U collisions than in the side-on-side U + U collisions, an exactly opposite behavior from the correlations generated by the elliptic flow of the quark–gluon plasma: a study of azimuthal correlations in the U + U collisions may thus help to disentangle the two sources of correlations. We demonstrate that the cross section for two-gluon production in heavy–light ion collisions contains a power-law infrared (IR) divergence even for fixed produced gluon momenta: while Saturation effects in the target regulate some of the power-law IR-divergent terms in the lowest-order expression for the two-gluon correlator, other power-law IR-divergent terms remain, possibly due to absence of Saturation effects in the dilute projectile. Finally we rewrite our result for the two-gluon production cross-section in a k T -factorized form, obtaining a new factorized expression involving a convolution of one- and two-gluon Wigner distributions over both the transverse momenta and impact parameters. We show that the two-gluon production cross-section depends on two different types of unintegrated two-gluon Wigner distribution functions.
-
long range rapidity correlations in heavy light ion collisions
International Journal of Modern Physics: Conference Series, 2014Co-Authors: Yuri V Kovchegov, Douglas E. WertepnyAbstract:We study two-particle long-range rapidity correlations arising in the early stages of heavy ion collisions in the Saturation/Color Glass Condensate framework, assuming for simplicity that one colliding nucleus is much larger than the other. We calculate the two-gluon production cross section while including all-order Saturation effects in the heavy nucleus with the lowest-order rescattering in the lighter nucleus. We find four types of correlations in the two-gluon production cross section: (i) geometric correlations, (ii) HBT correlations accompanied by a back-to-back maximum, (iii) away-side correlations, and (iv) near-side azimuthal correlations which are long-range in rapidity. The geometric correlations (i) are due to the fact that nucleons are correlated by simply being confined within the same nucleus and may lead to long-range rapidity correlations for the produced particles without strong azimuthal angle dependence. Somewhat surprisingly, long-range rapidity correlations (iii) and (iv) have exactly the same amplitudes along with azimuthal and rapidity shapes: one centered around Δϕ = π with the other one centered around Δϕ = 0 (here Δϕ is the azimuthal angle between the two produced gluons). We thus observe that the early-time CGC dynamics in nucleus-nucleus collisions generates azimuthal non-flow correlations which are qualitatively different from jet correlations by being long-range in rapidity. If strong enough, they have the potential of mimicking the elliptic (and higher-order even-harmonic) flow in the di-hadron correlators: one may need to take them into account in the experimental determination of the flow observables.
-
Long-range rapidity correlations in heavy–light ion collisions
Nuclear Physics A, 2013Co-Authors: Yuri V Kovchegov, Douglas E. WertepnyAbstract:Abstract We study two-particle long-range rapidity correlations arising in the early stages of heavy ion collisions in the Saturation/Color Glass Condensate framework, assuming for simplicity that one colliding nucleus is much larger than the other. We calculate the two-gluon production cross section while including all-order Saturation effects in the heavy nucleus with the lowest-order rescattering in the lighter nucleus. We find four types of correlations in the two-gluon production cross section: (i) geometric correlations, (ii) HBT correlations accompanied by a back-to-back maximum, (iii) away-side correlations, and (iv) near-side azimuthal correlations which are long-range in rapidity. The geometric correlations (i) are due to the fact that nucleons are correlated by simply being confined within the same nucleus and may lead to long-range rapidity correlations for the produced particles without strong azimuthal angle dependence. Somewhat surprisingly, long-range rapidity correlations (iii) and (iv) have exactly the same amplitudes along with azimuthal and rapidity shapes: one centered around Δ ϕ = π with the other one centered around Δ ϕ = 0 (here Δϕ is the azimuthal angle between the two produced gluons). We thus observe that the early-time CGC dynamics in nucleus–nucleus collisions generates azimuthal non-flow correlations which are qualitatively different from jet correlations by being long-range in rapidity. If strong enough, they have the potential of mimicking the elliptic (and higher-order even-harmonic) flow in the di-hadron correlators: one may need to take them into account in the experimental determination of the flow observables.
Sethuraman Panchanathan - One of the best experts on this subject based on the ideXlab platform.
-
ASSETS - Learning and perceiving Colors haptically
Proceedings of the 8th international ACM SIGACCESS conference on Computers and accessibility - Assets '06, 2006Co-Authors: Kanav Kahol, Jamieson French, Laura Bratton, Sethuraman PanchanathanAbstract:Color is an integral part of spatial perception and there is a need to develop systems that render Color information accessible to blind individuals. A novel system that allows learning, presentation and analysis of Color information, designed in consultations with focus groups of individuals who are blind is proposed. Our system is based on a methodology that renders Colors as textures through a haptic device. The aim of the proposed approach is to enable Color perception and provide a basis for assessing Color similarity. Initial testing of the system shows that both blind individuals and sighted individuals can recognize Colors through our approach and further assess similarity between Colors through the system. A space was obtained through multidimensional scaling performed on similarity scores between pairs of Colors as presented through our system. This space obtained high congruency with the chromaticity diagram and the hue Saturation Color wheel which shows the validity of our system to allow Color visualization. A realtime system based on the proposed mapping is designed to allow realtime Color perception.
Shen-jie Shiu - One of the best experts on this subject based on the ideXlab platform.
-
Fuzzy System Learned Through Fuzzy Clustering and Support Vector Machine for Human Skin Color Segmentation
IEEE Transactions on Systems Man and Cybernetics - Part A: Systems and Humans, 2007Co-Authors: Chia-feng Juang, Shih-hsuan Chiu, Shen-jie ShiuAbstract:This paper proposes a Fuzzy System learned through Fuzzy Clustering and Support Vector Machine (FS-FCSVM). The FS-FCSVM is a fuzzy system constructed by fuzzy if-then rules with fuzzy singletons in the consequence. The structure of FS-FCSVM is constructed by fuzzy clustering on the input data, which helps to reduce the number of rules. Parameters in FS-FCSVM are learned through a support vector machine (SVM) for the purpose of achieving higher generalization ability. In contrast to nonlinear kernel-based SVM or some other fuzzy systems with a support vector learning mechanism, both the number of parameters/rules in FS-FCSVM and the computation time are much smaller. FS-FCSVM is applied to skin Color segmentation. For Color information representation, different types of features based on scaled hue and Saturation Color space are used. Comparisons with a fuzzy neural network, the Gaussian kernel SVM, and mixture of Gaussian classifiers are performed to show the advantage of FS-FCSVM.
Hongbin Zha - One of the best experts on this subject based on the ideXlab platform.
-
Robust human tracking based on multi-cue integration and mean-shift
Pattern Recognition Letters, 2009Co-Authors: Hong Liu, Hongbin Zha, Yuexian Zou, Lin ZhangAbstract:Multi-cue integration has been researched extensively for robust visual tracking. Researchers aim to use multiple cues under the probabilistic methods, such as Particle Filtering and Condensation. On the other hand, Color-based Mean-Shift has been addressed as an effective and fast algorithm for tracking Color blobs. However, this deterministic searching method suffers from objects with low Saturation Color, Color clutter in backgrounds and complete occlusion for several frames. This paper integrates multiple cues into Mean-Shift algorithm to extend its application areas of the fast and robust deterministic searching method. A direct multiple cues integration method with an occlusion handler is proposed to solve the common problems in Color-based deterministic methods. Moreover, motivated by the idea of tuning weight of each cue in an adaptive way to overcome the rigidity of the direct integration method, an adaptive multi-cue integration based Mean-Shift framework is proposed. A novel quality function is introduced to evaluate the reliability of each cue. By using the adaptive integration method, the problem of changing appearance caused by object rotation can be solved. Extensive experiments show that this method can adapt the weight of individual cue efficiently. When the tracked Color blob is invisible for human bodies' rotation, the Color cue is compensated by motion cue. When the Color blob becomes visible again, the Color cue will become dominating as well. Furthermore, the direct-cue-integration method with an occlusion handler is combined with the adaptive integration method to extend the application areas of the adaptive method to full occlusion cases.
-
SMC - Robust Mean Shift Tracking Based on Multi-Cue Integration
2006 IEEE International Conference on Systems Man and Cybernetics, 2006Co-Authors: Hong Liu, Hongbin ZhaAbstract:Color-based mean shift has been addressed as an effective and fast algorithm for tracking Color blobs. This deterministic searching method suffers from low Saturation Color object, Color clutter in backgrounds and complete occlusion for several frames. This paper proposes a direct motion-Color integration method to solve the low Saturation Color problem and the Color background clutter problem. Based on the direct cue integration, an occlusion handler that is able to deal with long term full occlusion is proposed to solve the complete occlusion problem as well. Moreover, motivated by the idea of tuning weight of each cue according to its performance, a method of adaptive multi-cue integration based mean shift is proposed. Weights of each cue are adjusted according to a quality function, which is used to evaluate the performance of each cue in the adaptive integration scheme. Extensive experiments show that this method can adapt the weight of individual cue efficiently, and increase the robustness of tracking in various conditions.
