Open Access

We discuss the modification of the properties of the tetraquark-like Tcc(3875)+ and Tc¯c¯(3875)− states in dense nuclear matter. We consider the T+cc and T−c¯c¯ in vacuum as purely isoscalar D∗D and D¯¯¯¯∗D¯¯¯¯ S-wave bound states, respectively, dynamically generated from a heavy-quark effective interaction between the charmed mesons. We compute the D, D¯¯¯¯, D∗, and D¯¯¯¯∗ spectral functions embedded in a nuclear medium and use them to determine the corresponding T+cc and T−c¯c¯ self energies and spectral functions. We find important modifications of the D∗D and D¯¯¯¯∗D¯¯¯¯ scattering amplitudes and of the pole position of these exotic states already for ρ0/2, with ρ0 the normal nuclear density. We also discuss the dependence of these results on the D∗D (D¯¯¯¯∗D¯¯¯¯) molecular component in the T+cc (T−c¯c¯ ) wave-function. Owing to the different nature of the D(∗)N and D¯¯¯¯(∗)N interactions, we find characteristic changes of the in-medium properties of the Tcc(3875)+ and Tc¯c¯(3875)−, which become increasingly visible as the density increases. The experimental confirmation of the found distinctive density-pattern will give support to the molecular picture of these tetraquark-like states, since in the case they were colourless compact quark structures the density behaviour of their respective nuclear medium spectral functions would likely be similar. Finally, we perform similar analyses for the isoscalar JP=1+ heavy-quark spin symmetry partners of the T+cc (T∗+cc) and the T−c¯c¯ (T∗−c¯c¯) by considering the D∗0D∗+ and D¯¯¯¯∗0D∗− scattering T−matrices.

We discuss the modification of the properties of the tetraquark-like Tcc(3875)+ and Tc¯c¯(3875)− states in dense nuclear matter. We consider the T+cc and T−c¯c¯ in vacuum as purely isoscalar D∗D and D¯¯¯¯∗D¯¯¯¯ S-wave bound states, respectively, dynamically generated from a heavy-quark effective interaction between the charmed mesons. We compute the D, D¯¯¯¯, D∗, and D¯¯¯¯∗ spectral functions embedded in a nuclear medium and use them to determine the corresponding T+cc and T−c¯c¯ self energies and spectral functions. We find important modifications of the D∗D and D¯¯¯¯∗D¯¯¯¯ scattering amplitudes and of the pole position of these exotic states already for ρ0/2, with ρ0 the normal nuclear density. We also discuss the dependence of these results on the D∗D (D¯¯¯¯∗D¯¯¯¯) molecular component in the T+cc (T−c¯c¯ ) wave-function. Owing to the different nature of the D(∗)N and D¯¯¯¯(∗)N interactions, we find characteristic changes of the in-medium properties of the Tcc(3875)+ and Tc¯c¯(3875)−, which become increasingly visible as the density increases. The experimental confirmation of the found distinctive density-pattern will give support to the molecular picture of these tetraquark-like states, since in the case they were colourless compact quark structures the density behaviour of their respective nuclear medium spectral functions would likely be similar. Finally, we perform similar analyses for the isoscalar JP=1+ heavy-quark spin symmetry partners of the T+cc (T∗+cc) and the T−c¯c¯ (T∗−c¯c¯) by considering the D∗0D∗+ and D¯¯¯¯∗0D∗− scattering T−matrices.

Complementary to high-energy experimental efforts, indirect astrophysical searches of particles beyond the standard model have long been pursued. The present article follows the latter approach and considers, for the first time, the self-consistent treatment of the energy losses from dark flavoured particles produced in the decay of hyperons during a core-collapse supernova (CCSN). To this end, general relativistic supernova simulations in spherical symmetry are performed, featuring six-species Boltzmann neutrino transport, and covering the long-term evolution of the nascent remnant proto-neutron star (PNS) deleptonization for several tens of seconds. A well-calibrated hyperon equation of state (EOS) is therefore implemented into the supernova simulations and tested against the corresponding nucleonic model. It is found that supernova observables, such as the neutrino signal, are robustly insensitive to the appearance of hyperons for the simulation times considered in the present study. The presence of hyperons enables an additional channel for the appearance of dark sector particles, which is considered at the level of the Λ hyperon decay. Assuming massless particles that escape the PNS after being produced, these channels expedite the deleptonizing PNS and the cooling behaviour. This, in turn, shortens the neutrino emission timescale. The present study confirms the previously estimated upper limits on the corresponding branching ratios for low and high mass PNS, by effectively reducing the neutrino emission timescale by a factor of two. This is consistent with the classical argument deduced from the neutrino detection associated with SN1987A.

We discuss the effects induced by the potential presence of hyperons in hot and ultra-dense matter within the context of neutron star mergers. Specifically, we address their effect on the dominant post-merger frequency of the gravitational waves. By performing a simulation campaign with a large sample of hyperonic and nucleonic equations of state, we explicitly show that the unique thermal behavior of hyperonic equations of state results in a systematic shift of the dominant frequency with respect to the nucleonic reference level. The predicted shift has values of up to 150 Hz, and it could be detected with the newest generations of gravitational wave detectors. Thus this approach opens a new path for signaling the presence of hyperons in neutron star remnant matter.

Abstract. Since its first detection, the interesting properties of the Tcc(3875)+ have made it to be one of the most prominent tetraquark-like states up to date. In this work we present a joint analysis of the T+cc and its charge-conjugated partner in a dense nuclear medium. We start by considering both states as purely isoscalar D* D and D¯*D¯ S -wave bound states, respectively. We use previous results for the in-medium D, D¯*D¯, D* and D* spectral functions to determine the modified two-meson amplitudes. We find important changes in the in-medium mass and width of both tetraquark-like resonances, which become more visible when increasing the nuclear density and molecular probabilities. The experimental confirmation of the found distinctive patterns will support the existence of molecular components in the T+cc and T-c¯c¯ wave functions.