Speaker
Kenji Morita
(Kyoto University)
Description
We show that $\Lambda\Lambda$ intensity correlation function $C(Q=k_1-k_2)$ measured in high energy heavy ion collisions can constrain the interaction between two $\Lambda$ [1].
For various $\Lambda\Lambda$ interaction potentials in literature, summarized in the figure with corresponding low energy scattering parameters, we compute the $\Lambda\Lambda$ relative wave function $\Psi(x_1,x_2;Q)$ by assuming modification of the wave function in $S-$wave and discuss the relation between the scattering parameters and the behavior of the correlation function
$
C(Q,K) = \frac{\int dx_1 \int dx_2
S(x_1,K)S(x_2,K)|\Psi(x_1,x_2;Q)|^2}{\int dx_1 S(x_1,k_1) \int dx_2 S(x_2,k_2)},
$
where $S(x,K)$ denote the source function which is the phase space distribution of $\Lambda$ at freeze-out.
Employing a Gaussian source model with longitudinal and transverse
expansion as a source function of $\Lambda$, we discuss the parameter
ranges of the scattering length $a_0$ and the effective range
$r_{\text{eff}}$ constrained from experimental data in Au+Au collisions
at $\sqrt{s_{NN}}=200$GeV measured by the STAR collaboration [2].
The contribution from electromagnetic decay $\Sigma^0 \rightarrow \Lambda \gamma$
is found to be important. We also point out the existence of residual
correlation in the high $Q$ region which cannot be explained in the
present framework.
Consequently, we obtained a constraint on the scattering length
$1/a_0 < -0.8 \text{fm}^{-1}$.
We will also address an application of this method to other systems,
such as $\Omega-N$ [3].
1. K.Morita, T.Furumoto, A.Ohnishi, Phys. Rev. C **91**, 024916 (2015).
2. L.Adamczyk et al. (STAR Collaboration), Phys. Rev. Lett. **114**, 022301 (2015).
3. K.Morita, A.Ohnishi, T.Hatsuda, work in progress.
![$\Lambda\Lambda$ scattering parameters][4]
[4]: http://www2.yukawa.kyoto-u.ac.jp/~kenji.morita/LL2.jpg
Primary author
Kenji Morita
(Kyoto University)
Co-authors
Akira Ohnishi
(Kyoto University)
Takenori Furumoto
(Ichinoseki College)
