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Register a new userChiral effective Lagrangian for excited heavy-light mesons from QCD
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We derive the chiral effective Lagrangian for excited heavy-light mesons from QCD under proper approximations. We focus on the chiral partners with $j_l^P=frac{3}{2}^+$ and $j_l^P=frac{3}{2}^-$ which amounts to ($1^+,2^+$) and ($1^-,2^-$) states respectively. The low energy constants including the masses of the chiral partners are calculated. The calculated spectrum for the excited mesons are found roughly consistent with experimental data. In addition, our results indicate that quantum numbers of $B_J(5970)$ can be identified with $1^-$ or $2^-$.
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As a successive work to [Phys.Rev.D 102 (2020), 034034], we derive the $1/m_Q$ corrections to chiral effective Lagrangian for heavy-light mesons from QCD under proper approximations. The low energy constants in the effective Lagrangian are expressed in terms of the light quark self-energy and heavy quark mass $m_Q$. Numerical results of the low energy constants with $1/m_Q$ corrections are given. We find that the results of pion decay constant and the masses of heavy-light mesons are improved coherently compared to that obtained in the heavy quark limit.
A previous formal derivation of the effective chiral Lagrangian for low-lying pseudoscalar mesons from first-principles QCD without approximations [Wang et al., Phys. Rev. D61, (2000) 54011] is generalized to further include scalar, vector, and axial-vector mesons. In the large Nc limit and with an Abelian approximation, we show that the properties of the newly added mesons in our formalism are determined by the corresponding underlying fundamental homogeneous Bethe--Salpeter equation in the ladder approximation, which yields the equations of motion for the scalar, vector, and axial-vector meson fields at the level of an effective chiral Lagrangian. The masses appearing in the equations of motion of the meson fields are those determined by the corresponding Bethe--Salpeter equation.
We summarize recently improved results for the pseudoscalar [1,2] and vector [3] meson decay constants and their ratios from QCD spectral sum rules where N2LO + estimate of the N3LO PT and power corrections up to d< 6 dimensions have been included in the SVZ expansion. The optimal results based on stability criteria with respect to the variations of the Laplace/Moments sum rule variables, QCD continuum threshold and subtraction constant mu are compared with recent sum rules and lattice calculations. To understand the apparent tension between some recent results for f_B*/f_B, we present in Section 8 a novel extraction of this ratio from heavy quark effective theory (HQET) sum rules by including the normalization factor (M_b/M_B)^2 relating the pseudoscalar to the universal HQET correlators for finite b-quark and B-meson masses. We obtain f_B*/f_B=1.025(16) in good agreement with the one 1.016(16) from (pseudo)scalar sum rules in full QCD [3]. We complete the paper by including new improved estimates of the scalar, axial-vector and B^*_c meson decays constants (Sections 11-13). For further phenomenological uses, we attempt to extract a Global Average of different sum rules and lattice determinations of the decay constants which are summarized in Tables 2-6. We do not found any deviation of these SM results from the present data.
Using the SU(3) flavor symmetry, we construct the chiral Lagrangians for the light and heavy pentaquarks. The correction from the nonzero quark is taken into account perturbatively. We derive the Gell-Mann$-$Okubo type relations for various pentaquark multiplet masses and Coleman-Glashow relations for anti-sextet heavy pentaquark magnetic moments. We study possible decays of pentaquarks into conventional hadrons. We also study the interactions between and within various pentaquark multiplets and derive their coupling constants in the symmetry limit. Possible kinematically allowed pionic decay modes are pointed out.
We study the reactions $gammagammarightarrow pi^0pi^0$, $pi^+pi^-$, $K^0bar{K}^0$, $K^+K^-$, $eta eta$ and $pi^0eta$ based on a chiral Lagrangian with dynamical light vector mesons as formulated within the hadrogenesis conjecture. At present our chiral Lagrangian contains 5 unknown parameters that are relevant for the photon fusion reactions. They parameterize the strength of interaction terms involving two vector meson fields. These parameters are fitted to photon fusion data $gammagammarightarrow pi^0pi^0$, $pi^+pi^-, pi^0eta$ and to the decay $etarightarrowpi^0gammagamma$. In order to derive gauge invariant reaction amplitudes in the resonance region constraints from micro-causality and exact coupled-channel unitarity are used. Our results are in good agreement with the existing experimental data from threshold up to about 0.9 GeV for the two-pion final states. The $a_0$ meson in the $pi^0eta$ channel is dynamically generated and an accurate reproduction of the $gammagammarightarrow pi^0eta$ data is achieved up to 1.2 GeV. Based on our parameter sets we predict the $gammagammarightarrow $ $K^0bar{K}^0$, $K^+K^-$, $eta eta$ cross sections.
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