Υ suppression in a hadron gas

Abstract

In this work we study the interactions of bottom mesons which lead to Υ production and absorption in hot hadronic matter. We use effective Lagrangians to calculate the Υ production cross section in processes such asB ( * ) + B ( * ) → Υ + (π, ρ) and also the Υ absorption cross section in the corresponding inverse processes. We update and extend previous calculations by Lin and Ko, introducing anomalous interactions. The obtained cross sections are used as input to solve the rate equation which allows us to follow the time evolution of the Υ multiplicity. In contrast to previous conjectures, our results suggest that the interactions in the hadron gas phase strongly reduce the Υ abundance.

Quarkonium interactions with (hot) hadronic matter

“…Our results for the channel ϒπ → (B B * + c.c.) can be contrasted to the ones of preceding works [36,37], obtained employing different approaches. Taking the respective maximum values, this cross section in Fig.…”

“…Concerning the control mechanism of the energy-dependence of cross sections, previous works [36,37] obtained the correct behavior of the amplitudes at high energies for some reactions to be considered by making use of form factors with different functional forms and cutoff values without a more fundamental justification. In the present study we adopt a different way, based on the method of unitarized coupled channel amplitudes.…”

“…Refs. [36,37]. One important feature of this model is that the only non-vanishing cross section at tree level is the one related to the process with final state (B B * + c.c.…”

“…They found that the values of cross sections σ ϒπ and σ ϒρ are deeply influenced by the these choices of form factors, cutoffs and coupling constants. Besides, they found contrasting results: while [36] concludes that the absorption of ϒ by comoving hadrons is negligible due to their small thermal averages, in [37] the anomalous interactions are taken into account and the ϒ abundance may suffer a sizable reduction in hadronic phase.…”

“…As far as we are aware, Refs. [36,37] have calculated cross sections of processes involving ϒ absorption by π, ρ mesons in a hot hadron gas. They make use of distinct effective hadronic Lagrangians, form-factors and cutoffs at the interaction vertices.…”