Open bottom states and theB¯-meson propagation in hadronic matter

Abstract

The interaction and propagation ofB mesons with light mesons, N and Δ, is studied within a unitarized approach based on effective models that are compatible with chiral and heavy-quark symmetries. We find several heavy-quark spin doublets in the open bottom sectors, whereB andB Ã mesons are present. In the meson sector we find several resonant states, among them a B 0 and a B 1 with masses 5530 MeV and 5579 MeV as well as B Ã s0 and B Ã s1 narrow states at 5748 MeV and 5799 MeV, respectively. They form two doublets with no experimental identification yet, the first one being the bottom counterpart of the D 0 ð2400Þ and D 1 ð2430Þ states, and the second bottom doublet associated to the ubiquitous D Ã s0 ð2317Þ and the D s1 ð2460Þ. In the baryon sector, several Λ b and Σ b doublets are identified, among them the one given by the experimental Λ b ð5910Þ and Λ Ã b ð5921Þ. Moreover, one of our states, the Σ Ã b ð5904Þ, turns out to be the bottom counterpart of the experimental Σ Ã ð1670Þ and predicted Σ Ã c ð2550Þ, which is a case for discovery. We finally analyze different transport coefficients for theB meson in hot matter, such as those formed in heavy-ion collisions at the Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC). For RHIC/LHC energies, the main contribution to the coefficients comes from the interaction ofB mesons with pions. However, we also include the effects of baryonic density which might be sizable at temperatures T ≲ 100 MeV, as the chemical potential is expected to increase in the last stages of the expansion. We conclude that although the relaxation time decreases with larger baryonic densities, theB meson does not thermalize at RHIC/LHC energies, representing an ideal probe for the initial bottom distribution.

Single electrons from heavy-flavor mesons in relativistic heavy-ion collisions

“…From this effective Lagrangian one can compute the tree-level amplitude (or potential), which describes the scattering of a heavy meson off a light meson as worked out in Refs. [68,69]. At leading order in the heavy-quark expansion one gets a common result for all heavy mesons due to the exact heavy-flavor symmetry and heavy-quark spin symmetry (HQSS).…”

“…We refer the reader to Refs. [62,64,[66][67][68][69] for technical details. The unitarization procedure allows for the possibility of generating resonant states as poles of the scattering amplitude T ij .…”

“…The position and the width of these states as well as the coupling of these states to the main channels have been carefully analyzed in Ref. [68,69] in connection with several transport coefficients in heavy-ion collisions.…”

“…(16) f π is the pion decay constant in the chiral limit, and h i are the low-energy constants at NLO in the chiral expansion (see Ref. [68,69] for details). Finally, s, u denote the Mandelstam variables and p a the four-momentum of the a−particle in the scattering (1, 2 → 3, 4).…”

“…A description of their interactions has been developed in Refs. [62][63][64][65][66][67][68][69][70] using effective field theory. Moreover, after the application of an effective theory, one should implement to the scattering amplitudes a unitarization method to better control the behavior of the cross sections at moderates energies.…”