Song et al. [Phys. Rev. C 102, 065208 (2020)] presented results for the $Lambda_c N$ interaction based on an extrapolation of lattice simulations by the HAL QCD Collaboration at unphysical quark masses to the physical point via covariant chiral effective field theory. We point out that their predictions for the $^3D_1$ partial wave disagree with available lattice results. We discuss the origin of that disagreement and present a comparison with predictions from conventional (non-relativistic) chiral effective field theory.
We study the prospects of using femtoscopic low-momentum correlation measurements at the Large Hadron Collider to access properties of the J/psi-nucleon interaction. The QCD multipole expansion in terms of the J/psi chromopolarizability relates the forward scattering amplitude to a key matrix element to the origin of the nucleon mass problem, the average chromoelectric gluon distribution in the nucleon. We use information on the J/psi-nucleon interaction provided by lattice QCD simulations and phenomenological models to compute J/psi-nucleon correlation functions. The computed correlation functions show clear sensitivity to the interaction, in particular to the J/psi chromopolarizability.
$eta_c$-nucleus bound state energies are calculated for various nuclei. Essential input for the calculations, namely the medium-modified $D$ and $D^{*}$ meson masses, as well as the density distributions in nuclei, are calculated within the quark-meson coupling (QMC) model. The attractive potentials for the $eta_c$ meson in the nuclear medium originate from the in-medium enhanced $DD^{*}$ loops in the $eta_c$ self-energy. Our results suggest that the $eta_c$ meson should form bound states with all the nuclei considered.
We study the prospects for deducing constraints on the interaction of charmed baryons with nucleons from measurements of two-particle momentum correlation functions for $Lambda_c p$. The correlation functions are calculated for $Lambda_c N$ and $Sigma_c N$ interactions that have been extrapolated from lattice QCD simulations at unphysical masses of $m_pi=410-570$ MeV to the physical point using chiral effective field theory as guideline. In addition, we consider phenomenological $Y_c N$ models from the literature to explore the sensitivity of the results to the properties of the interaction in detail. We find that a measurement of the $Lambda_c p$ correlation functions could indeed allow one to discriminate between strongly attractive $Lambda_c N$ forces, as predicted by some phenomenological models, and a weakly attractive interaction as suggested by the presently available lattice simulations.
We discuss the effects of quenched disorder in a dilute Bose-Einstein condensate confined in a hard walls trap. Starting from the disordered Gross-Pitaevskii functional, we obtain a representation for the quenched free energy as a series of integer moments of the partition function. Positive and negative disorder-dependent effective coupling constants appear in the integer moments. Going beyond the mean-field approximation, we compute the static two-point correlation functions at first-order in the positive effective coupling constants. We obtain the combined contributions of effects due to boundary conditions and disorder in this weakly disordered condensate. The ground state renormalized density profile of the condensate is presented. We also discuss the appearance of metastable and true ground states for strong disorder, when the effective coupling constants become negative.
We investigate the production of exotic tetraquarks, $QQbar{q}bar{q} equiv T_{QQ}$ ($Q=c$ or $b$ and $q=u$ or $d$), in relativistic heavy-ion collisions using the quark coalescence model. The $T_{QQ}$ yield is given by the overlap of the density matrix of the constituents in the emission source with the Wigner function of the produced tetraquark. The tetraquark wave function is obtained from exact solutions of the four-body problem using realistic constituent models. The production yields are typically one order of magnitude smaller than previous estimations based on simplified wave functions for the tetraquarks. We also evaluate the consequences of the partial restoration of chiral symmetry at the hadronization temperature on the coalescence probability. Such effects, in addition to increasing the stability of the tetraquarks, lead to an enhancement of the production yields, pointing towards an excellent discovery potential in forthcoming experiments. We discuss further consequences of our findings for the search of exotic tetraquarks in central Pb+Pb collisions at the LHC.
We present $Phi$- and $J/Psi$--nuclear bound state energies and absorption widths for some selected nuclei, using potentials in the local density approximation computed from an effective Lagrangian approach combined with the quark-meson coupling model. Our results suggest that these mesons should form bound states with all the nuclei considered provided that these mesons are produced in nearly recoilless kinematics.
We study the temperature and baryon density dependence of the masses of the lightest charmed baryons $Lambda_c$, $Sigma_c$ and $Sigma^*_c$. We also look at the effects of the temperature and baryon density on the binding energies of the $Lambda_c N$ and $Lambda_c Lambda_c$ systems. Baryon masses and baryon-baryon interactions are evaluated within a chiral constituent quark model. Medium effects are incorporated in those parameters of the model related to the dynamical breaking of chiral symmetry, which are the masses of the constituent quarks, the $sigma$ and $pi$ meson masses, and quark-meson couplings. We find that while the in-medium $Lambda_c$ mass decreases monotonically with temperature, those of $Sigma_c$ and $Sigma^*_c$ have a nonmonotonic dependence. These features can be understood in terms of a simple group theory analysis regarding the one-gluon exchange interaction in those hadrons. The in-medium $Lambda_c N$ and $Lambda_c Lambda_c$ interactions are governed by a delicate balance involving a stronger attraction due to the decrease of the $sigma$ meson mass, suppression of coupled-channel effects and lower thresholds, leading to shallow bound states with binding energies of a few~MeV. The $Lambda_c$ baryon could possibly be bound to a large nucleus, in qualitative agreement with results based on relativistic mean field models or QCD sum rules. Ongoing experiments at RHIC or LHCb or the planned ones at FAIR and J-PARC may take advantage of the present results.
We study a three-body system, formed by two identical heavy bosons and a light particle, in the Born-Oppenheimer approximation for an arbitrary dimension $D$. We restrict $D$ to the interval $2,<,D,<,4$, and derive the heavy-heavy $D$-dimensional effective potential proportional to $1/R^2$ ($R$ is the relative distance between the heavy particles), which is responsible for the Efimov effect. We found that the Efimov states disappear once the critical strength of the heavy-heavy effective potential $1/R^2$ approaches the limit $-(D-2)^2/4$. We obtained the scaling function for the $^{133}$Cs-$^{133}$Cs-$^6$Li system as the limit cycle of the correlation between the energies of two consecutive Efimov states as a function of $D$ and the heavy-light binding energy $E^{D}_2$. In addition, we found that the energy of the $(N+1)^{rm th}$ excited state reaches the two-body continuum independently of the dimension $D$ when $sqrt{E^{D}_2/E_3^{(N)}}=0.89$, where $E_3^{(N)}$ is the $N^{rm th}$ excited three-body binding energy.
We discuss a disordered $lambdavarphi^{4}+rhovarphi^{6}$ Landau-Ginzburg model defined in a d-dimensional space. First we adopt the standard procedure of averaging the disorder dependent free energy of the model. The dominant contribution to this quantity is represented by a series of the replica partition functions of the system. Next, using the replica symmetry ansatz in the saddle-point equations, we prove that the average free energy represents a system with multiple ground states with different order parameters. For low temperatures we show the presence of metastable equilibrium states for some replica fields for a range of values of the physical parameters. Finally, going beyond the mean-field approximation, the one-loop renormalization of this model is performed, in the leading order replica partition function.
