Transport properties of bottomed mesons in a hot mesonic gas

In this work we evaluate the B-meson drag and diffusion coefficients in a hot medium constituted of light mesons (pions, kaons and eta mesons). We treat the B-meson and B*-meson interaction with pseudo-Goldstone bosons in chiral perturbation theory at next-to-leading order within the constraints from heavy quark symmetry, and employ standard unitarization techniques of NLO amplitudes in order to account for dynamically generated resonances (leading to a more efficient heavy-flavor diffusion) and thus reach higher temperatures. We estimate individual meson contributions from the gas to the transport coefficients and perform a comparison with other findings in literature. We report a bottom relaxation length of about 80 fm at a temperature of 150 MeV and for typical momenta of 1 GeV, at which our approach is reliable. Compared to a charm relaxation length of 40 fm in the same conditions, we conclude that the B mesons provide a cleaner probe of the early stages of a heavy-ion collision.Comment: 14 pages, 16 figures, 3 tables. Version published in Phys.Rev.D87, 034019 (2013). Only minor improvements with respect to v1: corrected typos, further clarifications and updated reference

Heavy mesons in a hadronic medium: interaction and transport coefficients

We review the recent results of heavy meson diffusion in thermal hadronic matter. The interactions of D and B-bar mesons with other hadrons (light mesons and baryons) are extracted from effective field theories based on chiral and heavy-quark symmetries. When these guiding principles are combined with exact unitarity, physical values of the cross sections are obtained. These cross sections (which contain resonant contributions) are used to calculate the drag and diffusion coefficients of heavy mesons immersed in a thermal and dense medium. The transport coefficients are computed using a Fokker-Planck reduction of the Boltzmann equation.Comment: 4 pages, 3 figures. Contribution to the proceedings of the 15th International Conference on Strangeness in Quark Matter (SQM 2015), 06-11 Jul 2015. Dubna, Moscow region, Russi

D-meson diffusion in hadronic matter

We present effective-field-theory results with unitarized interactions on the D-meson transport coefficients in a gas populated by light mesons and baryons at finite temperature and baryochemical potential. The Fokker-Planck equation is used to compute the drag force, the relaxation time and the diffusion coefficients of D mesons for collisions at FAIR. At finite baryochemical potential, the combined effect of net baryonic density and sizable meson-baryon interaction makes the D mesons to relax more efficiently than in the case at zero baryochemical potential. We also describe the connection with the quark-gluon plasma phase in adiabatic trajectories on the phase diagram at both zero and finite baryochemical potential.Comment: 5 pages, 4 figures. Contribution to the FAIRNESS 2013 - Workshop for young scientists with research interests focused on FAIR physics. 15-21 September 2013, Berlin (Germany

Heating triangle singularities in heavy ion collisions

We predict that triangle singularities of hadron spectroscopy are strongly affected in heavy ion collisions. To do it we examine various effects of finite temperature on the triangle loop yielding the singularity within the hadron phase. Pion-containing triangles can be enhanced by exchanging them with the medium, but in other cases, especially with heavy-quark hadrons, known thermal effects over the particles mass and width can quickly reduce the singularity: at temperatures of about 150 MeV, below the transition to a quark-gluon plasma, even by two orders of magnitude. It appears that peaks seen in central heavy ion collisions are more likely to be hadrons than rescattering effects unless perhaps if a pion is involved in the triangle. The medium then acts as a spectroscopic filter.Comment: 5 pages, 7 plot

Role of f0(980)f_0(980) and a0(980)a_0(980) in the B−→π−K+K−B^- \to \pi ^- K^+ K^- and B−→π−K0Kˉ0B^- \to \pi ^- K^0 \bar K^0 reactions

In this work we study the role of the $f_0(980)$ and $a_0(980)$ resonances in the low $K ^{+} K^{-}$ and $K^0 \bar K^0$ invariant-mass region of the $B^- \to \pi ^- K^+ K^-$ and $B^- \to \pi ^- K^0 \bar K^0$ reactions. The amplitudes are calculated by using the chiral unitary $\rm SU(3)$ formalism, in which these two resonances are dynamically generated from the unitary pseudocalar-pseudoscalar coupled-channel approach. The amplitudes are then used as input in the evaluation of the mass distributions with respect to the $K^{+}K^{-}$ and $K^{0}\bar K^{0}$ invariant-masses, where the contributions coming from the $I=0$ and $I=1$ components are explicitly assessed. Furthermore, the contribution of the $K^{\ast }(892)^0 K^-$ production and its influence on the $\pi^{-} K^+$ and $K^{+} K^-$ systems are also evaluated, showing that there is no significant strength for small $K^{+} K^-$ invariant mass. Lastly, the final distributions of $M_{\rm inv}^2( K^{\pm}K^{\mp} )$ for the $B^{\mp} \to \pi ^{\mp} K^{\pm}K^{\mp}$ reactions are estimated and compared with the LHCb data. Our results indicate that the $I=0$ component tied to the $f_0(980)$ excitation generates the dominant contribution in the range of low $K ^{+} K^{-}$ invariant-mass.Comment: 11 pages, 10 figure

Traces of the new a0(1780)a_0(1780) resonance in the J/ψ→ϕK+K−(K0Kˉ0)J/\psi\to \phi K^+K^-(K^0\bar{K}^0) reaction

We study the $J/\psi \to \phi K \bar K$ decay, looking for differences in the production rates of $K^+ K^-$ or $K^0 \bar K^0$ in the region of 1700-1800 MeV, where two resonances appear dynamically generated from the vector-vector interaction. Two resonances are known experimentally in that region, the $f_0(1710)$ and a new resonance reported by the BABAR and BESIII collaborations. The $K \bar K$ should be produced with $I=0$ in that reaction, but due to the different $K^{*0}$ and $K^{*+}$ masses some isospin violation appears. Yet, due to the large width of the $K^*$, the violation obtained is very small and the rates of $K^+ K^-$ or $K^0 \bar K^0$ production are equal within $5\%$. However, we also find that due to the step needed to convert two vectors into $K \bar K$, a shape can appear in the $K \bar K$ mass distribution that can mimic the $a_0$ production around the $K^* \bar K^*$ threshold, and is simply a threshold effect.Comment: 13 pages; 11 figure

Inverse magnetic catalysis and size-dependent effects on the chiral symmetry restoration

We investigate the combined finite-size and thermo-magnetic effects on the properties of the quark matter, in the context of the two-flavored Nambu--Jona-Lasinio model. In particular, by using the mean-field approximation and the Schwinger proper time method in a toroidal topology with periodic or antiperiodic conditions, we evaluate the chiral phase transition, the constituent quark mass and the thermal and spatial susceptibilities under the change of the size, temperature and strength of external magnetic field. To take into account the inverse magnetic catalysis phenomenon, we make use of a recently proposed magnetized coupling constant. The findings suggest that the observables are strongly affected by the variation of the variables and also by the periodicity of the boundary conditions, with the final outcomes depending on the balance of these competing phenomena.Comment: 21 pages, 7 figure

A note on the tensor and vector exchange contributions to KKˉ→KKˉ,DDˉ→DDˉK \bar K \to K \bar K, D \bar D \to D \bar D and π+π−→π+π−\pi^+ \pi^-\to \pi^+ \pi^- reactions

In this note we study the tensor and vector exchange contributions to the elastic reactions involving the pseudoscalars mesons $\pi^+ \pi^-$, $K^{+}K^{-}$ and $D^{+}D^{-}$. In the case of the tensor-exchange contributions we assume that an intermediate tensor $f_2(1270)$ is dynamically generated from the interaction of two virtual $\rho$ mesons, with the use of a pole approximation. The calculation of the two-loop amplitude is facilitated since the triangle loops can be factorized and computed separately. The results show very small contributions coming from the tensor-exchange mechanisms when compared with those from the vector-exchange processes.Comment: 8 pages, 5 figure