p−p, p−Λ , and Λ−Λ correlations studied via femtoscopy in <

Abstract

We report on the first femtoscopic measurement of baryon pairs, such as p-p, p-, and-, measured by ALICE at the Large Hadron Collider (LHC) in proton-proton collisions at √ s = 7 TeV. This study demonstrates the feasibility of such measurements in pp collisions at ultrarelativistic energies. The femtoscopy method is employed to constrain the hyperon-nucleon and hyperon-hyperon interactions, which are still rather poorly understood. A new method to evaluate the influence of residual correlations induced by the decays of resonances and experimental impurities is hereby presented. The p-p, p-, and-correlation functions were fitted simultaneously with the help of a new tool developed specifically for the femtoscopy analysis in small colliding systems: Correlation Analysis Tool using the Schrödinger equation (CATS). Within the assumption that in pp collisions the three particle pairs originate from a common source, its radius is found to be equal to r 0 = 1.125 ± 0.018 (stat) +0.058 −0.035 (syst) fm. The sensitivity of the measured p-correlation is tested against different scattering parameters, which are defined by the interaction among the two particles, but the statistics is not sufficient yet to discriminate among different models. The measurement of the-correlation function constrains the phase space spanned by the effective range and scattering length of the strong interaction. Discrepancies between the measured scattering parameters and the resulting correlation functions at LHC and RHIC energies are discussed in the context of various models.

Loosely-bound objects produced in nuclear collisions at the LHC

“…This is possible by a precise modeling but is complicated because of the influence of feed-down on the correlation function and with this to the extracted interaction. The first published results for the pp, Λp and ΛΛ correlation functions are depicted in Figure 48 [221]. A detailed study is described there to extract the interaction parameter from these correlation functions.…”

Strangeness in nuclei and neutron stars

“…The particle emitting source is found to be very small in pp and p+Pb collisions at the LHC [38,39], that is of the order of 1 fm. These values are evaluated by using known interactions, with pp and K + p as benchmarks [35].…”

“…The hyperon-nucleon (Y N ) interaction can be tested experimentally via scattering experiments employing secondary hyperon beams [196][197][198], impinging on hydrogen targets, or by means of the measurement of the correlation in the momentum space for hyperon-proton (Y p) pairs produced at colliders exploiting the femtoscopy technique [19,38,39,199].…”

Dark Matter Theory

“…In particular, if for some range of temperatures above MeV (i.e., safely above the range relevant for Big Bang nucleosynthesis) the energy density of the universe was dominated by some heavy but long-lived field many possibilities open up [33]. "Moduli" fields with these properties in fact occur quite naturally in many string theory constructions [34]. Detailed calculations show that in this case Binos can indeed be good DM candidates in generic parts of MSSM parameter space if the branching ratio for moduli decays into superparticles is very small, below 10 −4 or so [35].…”