Heavy + light pseudoscalar meson semileptonic transitions

A symmetry-preserving regularisation of a vector $$\times $$ × vector contact interaction (SCI) is used to deliver a unified treatment of semileptonic transitions involving $$\pi $$ π , K, $$D_{(s)}$$ D ( s ) , $$B_{(s,c)}$$ B ( s , c ) initial states. The framework is characterised by algebraic simplicity, few parameters, and the ability to simultaneously treat systems from Nambu–Goldstone modes to heavy+heavy mesons. Although the SCI form factors are typically somewhat stiff, the results are comparable with experiment and rigorous theory results. Hence, predictions for the five unmeasured $$B_{s,c}$$ B s , c branching fractions should be a reasonable guide. The analysis provides insights into the effects of Higgs boson couplings via current-quark masses on the transition form factors; and results on $$B_{(s)}\rightarrow D_{(s)}$$ B ( s ) → D ( s ) transitions yield a prediction for the Isgur–Wise function in fair agreement with contemporary data.

Investigating the Atomki anomaly in the framework of axial (ABJ) anomaly

An anomaly observed in the 8Be nuclear transition by the Atomki collaboration hints at a light, neutral boson decaying into an [Formula: see text] pair with a mass of about 17 MeV. In this paper, we study the Atomki anomaly in the framework of axial (ABJ) anomaly. Some theoretical results indicate that the X17 particle is the color singlet pseudoscalar. We take the X17 particle as a pseudoscalar meson [Formula: see text] system which has the axial (ABJ) anomaly, where [Formula: see text] denotes the up quark. Besides this, we also give an interpretation for E38 particle with a mass of about 38 MeV as a pseudoscalar meson [Formula: see text] system. We obtain the correct masses of the two pseudoscalars by a non-perturbative mass formula.

Two and three pseudoscalar production in e+e− annihilation and their contributions to (g − 2)μ

A coherent study of e+e− annihilation into two (π+π−, K+K−) and three (π+π−π0, π+π−η) pseudoscalar meson production is carried out within the framework of resonance chiral theory in energy region E ≲ 2 GeV. The work of [L.Y. Dai, J. Portolés, and O. Shekhovtsova, Phys. Rev. D88 (2013) 056001] is revisited with the latest experimental data and a joint analysis of two pseudoscalar meson production. Hence, we evaluate the lowest order hadronic vacuum polarization contributions of those two and three pseudoscalar processes to the anomalous magnetic moment of the muon. We also estimate some higher-order additions led by the same hadronic vacuum polarization. Combined with the other contributions from the standard model, the theoretical prediction differs still by (21.6 ± 7.4) × 10−10 (2.9σ) from the experimental value.

SU(3) analysis of fully-light tetraquarks in heavy meson weak decays

We perform a SU(3) analysis for both semi-leptonic and non-leptonic heavy meson weak decays into a pseudoscalar meson and a fully-light tetraquark in 10 or 27 representation. A reduction of the SU(3) representation tensor for the fully-light tetraquarks is produced and all the flavor components for each representation tensor are listed. The decay channels we analysis include $$B/D \rightarrow U/T~P~l\nu $$ B / D → U / T P l ν , $$B/D \rightarrow U/T~P $$ B / D → U / T P and $$B_c \rightarrow U/T~P/D$$ B c → U / T P / D , with U/T represents a fully-light tetraquark in 10 or 27 representation and P is a pseudoscalar meson. Finally, among these results we list all the golden decay channels which are expected to have more possibilities to be observed in experiments.

Relative scale setting for two-color QCD with Nf = 2 Wilson fermions

We determine the scale setting function and the pseudo-critical temperature on the lattice in Nf = 2 two-color QCD using the Iwasaki gauge and Wilson fermion actions. Although two-color QCD does not correspond to the real world, it is very useful as a good testing ground for three-color QCD. The scale setting function gives the relative lattice spacings of simulations performed at different values of the bare coupling. It is a necessary tool for taking the continuum limit. Firstly, we measure the meson spectra for various combinations of (β, κ) and find a line of constant physics in β – κ plane. Next, we determine the scale setting function via w0 scale in the gradient flow method. Furthermore, we estimate the pseudo-critical temperature at zero chemical potential from the chiral susceptibility.Combining these results, we can discuss the QCD phase diagram in which both axes are given by dimensionless quantities, namely, the temperature normalized by the pseudo-critical temperature on the lattice and the chemical potential normalized by the pseudoscalar meson mass. It makes it easy to compare among several lattice studies and also makes it possible to compare theoretical analyses and lattice studies in the continuum limit.

Two-body charmed baryon decays involving decuplet baryon in the quark-diagram scheme

In the quark-diagram scheme, we study the charmed baryon decays of $$\mathbf{B}_c\rightarrow \mathbf{B}^* M$$ B c → B ∗ M , where $$\mathbf{B}_c$$ B c is $$\Lambda _c^+$$ Λ c + or $$\Xi _c^{+(0)}$$ Ξ c + ( 0 ) , together with $$\mathbf{B}^*$$ B ∗ (M) the decuplet baryon (pseudoscalar meson). It is found that only two W-exchange processes are allowed to contribute to $$\mathbf{B}_c\rightarrow \mathbf{B}^* M$$ B c → B ∗ M . Particularly, we predict $${\mathcal {B}}(\Lambda _c^+ \rightarrow \Sigma ^{*0(+)} \pi ^{+(0)})=(2.8\pm 0.4)\times 10^{-3}$$ B ( Λ c + → Σ ∗ 0 ( + ) π + ( 0 ) ) = ( 2.8 ± 0.4 ) × 10 - 3 , which respects the isospin symmetry. Besides, we take into account the SU(3) flavor symmetry breaking, in order to explain the observation of $${\mathcal {B}}(\Lambda _c^+\rightarrow \Sigma ^{*+}\eta )$$ B ( Λ c + → Σ ∗ + η ) . For the decays involving $$\Delta ^{++}(uuu)$$ Δ + + ( u u u ) , we predict $${\mathcal {B}}(\Lambda _c^+\rightarrow \Delta ^{++} \pi ^-,\Xi _c^+ \rightarrow \Delta ^{++} K^-) =(7.0\pm 1.4,13.5\pm 2.7)\times 10^{-4}$$ B ( Λ c + → Δ + + π - , Ξ c + → Δ + + K - ) = ( 7.0 ± 1.4 , 13.5 ± 2.7 ) × 10 - 4 as the largest branching fractions in the singly Cabibbo-suppressed $$\Lambda _c^+,\Xi _c^+\rightarrow \mathbf{B}^*M$$ Λ c + , Ξ c + → B ∗ M decay channels, respectively, which are accessible to the LHCb, BELLEII and BESIII experiments.