ΛΛinteraction from relativistic heavy-ion collisions

Abstract

We investigate the two-particle intensity correlation function of in relativistic heavy-ion collisions. We find that the behavior of the correlation function at small relative momenta is fairly sensitive to the interaction potential and collective flows. By comparing the results of different source functions and potentials, we explore the effect of intrinsic collective motions on the correlation function. We find that the recent STAR data give a strong constraint on the scattering length and effective range of interaction, as −1.8 fm −1 < 1/a 0 < −0.8 fm −1 and 3.5 fm < r eff < 7 fm, respectively, if samples do not include the feed-down contribution from long-lived particles. We find that the feed-down correction for 0 decay reduces the sensitivity of the correlation function to the detail of the interaction. As a result, we obtain a weaker constraint, 1/a 0 < −0.8 fm −1 . Implication for the signal of existence of H -dibaryon is discussed. Comparison with the scattering parameters obtained from the double hypernucleus may reveal in-medium effects in the interaction.

Hadron-hadron Correlation And Interaction from Heavy-ion Collisions

“…Recently, ΛΛ correlation in high-energy heavy-ion collisions has been measured at the Relativistic Heavy-Ion Collider (RHIC) at the Brookhaven National Laboratory [30]. Theoretical analysis of data implies that the ΛΛ interaction is weakly attractive and there is no loosely bound state [31]. By comparison, another analysis suggests that ΛΛ interaction is weakly repulsive or there is a loosely bound state [30].…”

“…[30] and Ref. [31]. In the former, λ is regarded as a free parameter and the optimal value is found to be small, then the positive scattering length a 0 > 0 (decreasing phase shift) is favored.…”

Study of Hyperon Interaction from Heavy-Ion Collisions using STAR Detector at RHIC

“…However they have different sign compared to the LL model. The sign difference of the scattering length between the LL fit and fits in [26] originates from the assumption on the λ parameter in the LL model and it was discussed by A. Ohnishi [31] in detail during the conference. When the λ parameter was treated as a free parameter in the LL model, the fit results in two minima and a fixed value of λ = 0.45 gives a negative scattering length with a minimal χ 2 /NDF.…”

“…Numerical analysis of the final-state interaction effect using an s-wave scattering amplitude suggests the non-existence of a Λ − Λ resonance saturating the s-wave below the NΞ and ΣΣ thresholds. For more details please refer [21], where the shaded band represents the systematic error and the other filled points are fit to STAR data from K. Morita, T. Furumoto and A. Ohnishi [26]. Also, the Λ − Λ interaction parameters which reproduce the NAGARA event are shown as astrisk [27,28].…”

“…The fit parameters obtained with the residual correlation term are N = 1.006 ± 0.001, λ = 0.18 ± 0.05 +0.12 −0.06 , a 0 = −1.10 ± 0.37 +0.68 −0.08 fm, r eff = 8.52 ± 2.56 +2.09 −0.74 fm and r 0 = 2.96 ± 0.38 +0.96 −0.02 fm with χ 2 /NDF = 0.56. K. Morita, T. Furumoto and A. Ohnishi [26] fitted the measured CF with different interaction models. The scattering length obtained with those models has similar magnitude, as shown in Fig.…”