Juan Nieves

The ALICE Collaboration has recently shown interest in analyzing femtoscopic correlations involving light hadrons. In this paper, we review how \(\pi K\) data can be well reproduced using realistic interactions, while accurately describing the \(\kappa /K_0^*(700)\) resonance. For other light-hadron channels, qualitative insights into resonances such as \(\rho \) and \(a_0\) can be obtained through femtoscopic correlations. Moreover, we present preliminary results on a framework to interpret femtoscopy from a Chiral Perturbation Theory perspective. Published by the Jagiellonian University 2026 authors

We investigate how the $T_{cc}(3875)$ and its charge-conjugated partner behave when they are embedded in a dense nuclear medium or in a hot pionic medium. In vacuum, this state is modeled as an isoscalar $DD^\ast$ S-wave bound state, formed through effective interactions that correspond to different Weinberg compositeness models. Medium effects are introduced via the two-meson loop function, incorporating the self-energies acquired by $D^{(\ast)}$ mesons when they interact with the particles in the dense or hot mediums. The obtained lineshapes in the finite density nuclear matter reveal a charge-conjugation asymmetry stemming from the very different $D^{(\ast)}N$ and $\overline{D}{}^{(\ast)}N$ interactions. The temperature-induced changes on the $T_{cc}$ do not exhibit this charge-conjugation asymmetry, and are predicted to be extremely large near the crossover temperature of $T=150$ MeV. These predictions for both the finite-density and finite-temperature scenarios are highly sensitive to the Weinberg molecular component in the $T_{cc}$ wave function. If these finite-density or finite-temperature patterns could be measured, they would provide additional insight into the inner structure of this exotic state.

We revisit the strangeness $$-1$$ - 1 sector of the interaction between vector mesons of the $$\rho $$ ρ -nonet and $$1/2^+$$ 1 / 2 + ground state baryons ( VB ), within the unitary coupled-channel hidden gauge formalism. We adopt a renormalization scheme that induces a reasonable short-distance behavior of the two-hadron wave functions, which is the major limitation of femtoscopy techniques at this time. We perform an exhaustive spectroscopy study, implementing different improvements and considerations, and find compatibilities between the poles extracted from the present approach, and some of the states listed in the Review of Particle Physics. Finally, we predict several correlation functions (CFs) associated with various meson–baryon pairs in this sector, paying special attention to the distinctive and clear signatures produced by the dynamically generated states. To obtain realistic estimates for the CFs, we have calculated the production weights using the Thermal-FIST package. Such studies will shed light into the odd-parity $$\Lambda ^*$$ Λ ∗ and $$\Sigma ^*$$ Σ ∗ hadron spectra, up to 2 GeV, and will open the strategy to improve effective field theories by using low-energy constants fitted to femtoscopy data.

We solve the Lippmann-Schwinger equation (LSE) with a kernel that includes a regular finite-range potential and additional contact terms with derivatives. We employ distorted wave theory and dimensional regularization, as proposed in Nieves [Phys. Lett. B 568, 109 (2003)]. We analyze the spin singlet nucleon-nucleon $S$-wave as case of study, with the regular one-pion exchange (OPE) potential in this partial wave and up to $\mathcal{O}({Q}^{6})$ (six derivatives) contact interactions. We discuss in detail the renormalization of the LSE and show that the scattering amplitude solution of the LSE fulfills exact elastic unitarity and inherits the left-hand cut of the long-distance OPE amplitude. Furthermore, we proof that the LSE amplitude coincides with that obtained from the exact $N/D$ calculation, with the appropriate number and typology of subtractions to reproduce the effective range parameters taken as input to renormalize the LSE amplitude. The generalization to a higher number of derivatives is straightforward.