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Register a new userNuclear coalescence from correlation functions
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We derive a simple formula relating the cross section for light cluster production (defined via a coalescence factor) to the two-proton correlation function measured in heavy-ion collisions. The formula generalises earlier coalescence-correlation relations found by Scheibl & Heinz and by Mrowczynski for Gaussian source models. It motivates joint experimental analyses of Hanbury Brown-Twiss (HBT) and cluster yield measurements in existing and future data sets.
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In heavy ion collisions, elliptic flow $v_2$ and radial flow, characterized by event-wise average transverse momentum $[p_{mathrm{T}}]$, are related to the shape and size of the overlap region, which are sensitive to the shape of colliding atomic nuclei. The Pearson correlation coefficient between $v_2$ and $[p_{mathrm{T}}]$, $rho_2$, was found to be particularly sensitive to the quadrupole deformation parameter $beta$ that is traditionally measured in low energy experiments. Built on earlier insight that the prolate deformation $beta>0$ reduces the $rho_2$ in ultra-central collisions (UCC), we show that the prolate deformation $beta<0$ enhances the value of $rho_2$. As $beta>0$ and $beta<0$ are the two extremes of triaxiality, the strength and sign of $v_2^2-[p_{mathrm{T}}]$ correlation can be used to provide valuable information on the triaxiality of the nucleus. Our study provide further arguments for using the hydrodynamic flow as a precision tool to directly image the deformation of the atomic nuclei at extremely short time scale ($<10^{-24}$s).
UrQMD phase-space coalescence calculations for the production of deuterons are compared with available data for various reactions from the GSI/FAIR energy regime up to LHC. It is found that the production process of deuterons, as reflected in their rapidity and transverse momentum distributions in p+p, p+A and A+A collisions at a beam energies starting from the GSI energy regime around 1 AGeV and up to the LHC, are in good agreement with experimental data. We further explore the energy and centrality dependence of the d/p ratios. Finally, we discuss anti-deuteron production for selected systems. Overall, a good description of the experimental data is observed. The results are also compatible with thermal model estimates. Most importantly this good description is based only on a single set of coalescence parameters that is independent of energy system size and can also be applied for anti-deuterons.
We investigate the $LambdaLambda$ and $K^-p$ intensity correlations in high-energy heavy-ion collisions. First, we examine the dependence of the $LambdaLambda$ correlation on the $LambdaLambda$ interaction and the $LambdaLambda$ pair purity probability $lambda$. For small $lambda$, the correlation function needs to be suppressed by the $LambdaLambda$ interaction in order to explain the recently measured $LambdaLambda$ correlation data. By comparison, when we adopt the $lambda$ value evaluated from the experimentally measured $Sigma^0/Lambda$ ratio, the correlation function needs to be enhanced by the interaction. We demonstrate that these two cases correspond to the two analyses which gave opposite signs of the $LambdaLambda$ scattering length. Next, we discuss the $K^-p$ correlation function. By using the local $bar{K}N$ potential which reproduces the kaonic hydrogen data by SIDDHARTA, we obtain the $K^-p$ correlation function. We find that the $K^-p$ correlation can provide a complementary information with the $K^{-}p$ elastic scattering amplitude.
Kaon production in pion-nucleon collisions in nuclear matter is studied in the resonance model. To evaluate the in-medium modification of the reaction amplitude as a function of the baryonic density we introduce relativistic, mean-field potentials for the initial, final and intermediate mesonic and baryonic states. These vector and scalar potentials were calculated using the quark-meson coupling (QMC) model. The in-medium kaon production cross sections in pion-nucleon interactions for reaction channels with $Lambda$ and $Sigma$ hyperons in the final state were calculated at the baryonic densities appropriate to relativistic heavy ion collisions. Contrary to earlier work which has not allowed for the change of the cross section in medium, we find that the data for kaon production are consistent with a repulsive $K^+$-nucleus potential.
The production of slow nucleons in semi-inclusive deep inelastic electron scattering off nuclei, $A(e, eN)X$, is analyzed for kinematical conditions accessible at $HERA$ with the $HERMES$ detector. The sensitivity of the semi-inclusive cross section to possible medium-dependent modifications of the nucleon structure function is illustrated.
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