Results 1 - 10 of 20955
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[en] We consider the operator H = μA*A + ilambda A*(A+A*)A, where A* and A are the creation and annihilation operators. We shall show that the spectrum of the operator H is real. If μ>0, we shall give an asymptotic expansion of the semi-group esup(-tH) and the scattering elements associated to -H
[fr]On considere l'operateur H = μA*A + ilambda A*(A+A*)A, ou A designe l'operatuer d'annihilation et donc A* l'operateur de creation. On montre que le spectre de H est reel. Pour μ>0, on donne un comportement asymptotique du semi-groupe esup(-tH) et des elements de la matrice de diffusion associes a -H
[en] We provide a detailed survey study of dihadron azimuthal angle (Δφ) correlations in a broad range of transverse momentum (0.4 < pT < 10 GeV/c) and centrality (0-92%) in Au+Au collisions at √sNN = 200 GeV. The evolution of the jet shape and yield with pT seems to suggest two distinct components at the away-side pairs: a suppressed jet fragmentation component around Δφ ∼ π, and a medium-induced components around |Δφ-π| ∼ 1.1. The former dominates pT > 5 GeV/c and the later dominates at pT < 4 GeV/c.
[en] We present results on the system size dependence of high transverse momentum di-hadron correlations at √sNN = 200 GeV as measured by STAR at RHIC. Measurements in d+Au, Cu+Cu and Au+Au collisions reveal similar jet-like correlation yields at small angular separation (Δφ ∼ 0, Δη ∼ 0) for all systems and centralities. Previous measurements have shown that the away-side yield is suppressed in heavy-ion collisions. We present measurements of the away-side suppression as a function of transverse momentum and centrality in Cu+Cu and Au+Au collisions. The suppression is found to be similar in Cu+Cu and Au+Au collisions at a similar number of participants. The results are compared to theoretical calculations based on the parton quenching model and the modified fragmentation model. The observed differences between data and theory indicate that the correlated yields presented here will provide important constraints on medium density profile and energy loss model parameters.
[en] We consider a particle diffusing in the y-direction, dy/dt = η(t), subject to a transverse shear flow in the x-direction, dx/dt = f(y), where x ≥ 0 and x = 0 is an absorbing boundary. We treat the class of models defined by f(y) = ±v±(±y)α where the upper (lower) sign refers to y > 0 (y < 0). We show that the particle survives with probability Q(t) ∼ t-θ with θ = 1/4, independent of α, if v+ = v-. If v+ ≠ v-, however, we show that θ depends on both α and the ratio v+/v-, and we determine this dependence. (letter to the editor)
[en] In view of the scaling-in-the-mean hypothesis we propose a method to derive the relation between the momentum distributions in inclusive and semi-inclusive reactions. Our formula is useful to make a discrimination among the similar p/sub T/ distribution functions. We predict that the inclusive p/sub L/ distribution function in terms of p/sub L//< p/sub L/> shows energy dependence, comparing the Koba-Nielsen-Olesen scaling hypothesis and the two-component model for the multiplicity distributions
[en] We show that if in the particle beam there are linear correlations between energy of particles and their transverse positions and momenta (linear beam dispersions), then the transverse projected emittances always can be reduced by letting the beam to pass through magnetostatic system with specially chosen nonzero lattice dispersions. The maximum possible reduction of the transverse projected emittances occurs when all beam dispersions are zeroed, and the values of the lattice dispersions required for that are completely defined by the values of the beam dispersions and the beam rms energy spread and are independent from any other second-order central beam moments. Besides that, we prove that, alternatively, one can also use the lattice dispersions to remove linear correlations between longitudinal positions of particles and their transverse coordinates (linear beam tilts), but in this situation solution for the lattice dispersions is nonunique and the reduction of the transverse projected emittances is not guaranteed.
[en] Dependence of mean multiplicity on the transversal momentum transfer is studied. In framework of the model in view, based on possible probabilitic interpretation of the unitarity condition, and assuming a weak correlation between the recoil particle momenta in the intermediate n-particle state, it is shown that mean multiplicity increases linearly with rise of the transversal momentum. Behaviour of the mean multiplicity depending on the impact parameter is also studied
[en] The energy dependence of the ratio for antiparticle to particle in pp collisions of high energy is studied using the parton and hadron cascade and dynamically constrained phase-space coalescence models. The yield ratios of antimatter and matter for different masses are measured at various c.m energies. It is found that the yield ratios of antimatter and matter increase with the increase of the c.m energy of pp collisions until they gradually approach to 1 after the c.m energy is more than 200 GeV. The distribution of transverse momentum also has significant dependence on the energy and mass, i.e., the average transverse momentum increases when the c.m energy of pp collisions increase. The model results are compatible with the STAR and ALICE preliminary data. (author)
[en] We present a general argument which suggests that the Bartels-Lipatov-Vacca Odderon intercept should be equal to one to all orders in the perturbation theory. The argument is based on the validity of the so-called omega-expansion in the high energy limit. It can be further supported by the analogous pattern observed in the case of the anomalous dimensions which is a consequence of the momentum sum rule. In addition, we conjecture that the BFKL kernel should satisfy the transverse momentum sum rule. Finally, it is shown that the higher order kinematical effects do not change the BLV Odderon intercept.