Related papers: Isospin-breaking contributions to $\varepsilon'/\v…
We calculate isospin breaking in pion-nucleon scattering in the threshold region in the framework of covariant baryon chiral perturbation theory. All effects due to quark mass differences as well as real and virtual photons are consistently…
We present a study of the isospin-breaking (IB) corrections to pseudoscalar (PS) meson masses using the gauge configurations produced by the ETM Collaboration with $N_f=2+1+1$ dynamical quarks at three lattice spacings varying from 0.089 to…
We pursue the calculation of the model-independent component of the axion-photon-photon coupling in the $U(3)$ chiral perturbation theory up to next-to-leading order, with the emphasis on the isospin breaking effect. The mixing of the…
We systematically calculate the isospin violating decay, $D_s^*\to D_s\pi^0$, with the heavy meson chiral perturbation theory up to $\mathcal{O}(p^3)$ including the loop diagrams. The $\mathcal{O}(p^3)$ tree level amplitudes contain four…
It is shown that isospin-breaking corrections to the pion-deuteron scattering length can be very large, because of the vanishing of the isospin-symmetric contribution to this scattering length at leading order in chiral perturbation theory.…
An isospin analysis of $B\to \pi\pi$ decays yields $\sin 2\alpha$, where $\alpha$ is the usual CKM angle $\alpha\equiv {\rm arg} [-V_{td} V_{tb}^\ast/(V_{ud}V_{ub}^\ast)]$ without hadronic uncertainty if isospin is a perfect symmetry. Yet…
We employ Chiral Perturbation Theory (ChPT) to evaluate the complete set of pseudoscalar matrix elements, <0|P_f|pi^0,eta>, with P_f any of the flavor-diagonal pseudoscalar currents (f=u,d,s), to order (m_d-m_u), and to next-to-leading…
We investigate the isospin-violating mixing of the light scalar mesons a0(980) and f0(980) within the unitarized chiral approach. Isospin-violating effects are considered to leading order in the quark mass difference and electromagnetism.…
We discuss the electromagnetic corrections to the pion-nucleon scattering lengths generated by minimal e. m. coupling from a knowledge of the low energy expansion of the pion-nucleon elastic scattering amplitude as well as from the nucleon…
The strong isospin-breaking correction, Omega_{st}, which appears in estimates of the Standard Model value for the direct CP-violating ratio epsilon'/epsilon, is evaluated to next-to-leading order (NLO) in the chiral expansion using Chiral…
We use the observed $SU(3)$ breaking in the mass spectrum of mesons containing a single heavy quark to place restrictions on the light quark current masses. A crucial ingredient in this analysis is our recent first-principles calculation of…
An isospin analysis of $B\to\pi\pi$ decays yields $\sin 2\alpha$, where $\alpha$ is the usual CKM angle $\alpha\equiv arg [-V_{td}V_{tb}^\ast /(V_{ud}V_{ub}^\ast)]$, without hadronic uncertainty if isospin is a perfect symmetry. Isospin,…
The strange form factors of the proton are basic to an understanding of proton structure, and are presently the focus of many experiments. Before the strangeness effects can be extracted from data, it is necessary to calculate and remove…
We discuss the vector meson masses within the context of Chiral Perturbation Theory performing an expansion in terms of the momenta, quark masses and 1/Nc. We extend the previous analysis to include isospin breaking effects and also include…
The long-distance contributions to $K\to 2\pi$ amplitudes can be pinned down, using well established Chiral Perturbation Theory techniques. The strong S--wave rescattering of the two final pions generates sizeable chiral loop corrections,…
After updating the determination of the combination of Kobayashi-Maskawa elements $ \Im V_{td}V^*_{ts}$ according to our new estimate of the parameter $\hat B_K$, we study the CP-violating ratio $\epsilon'/\epsilon$ by means of hadronic…
The CP conserving amplitudes for the decays $K\to3\pi$ are calculated in Chiral Perturbation Theory. The calculation is made at the next-to-leading order including strong and local electromagnetic isospin breaking. A comparison is made…
The five different CP conserving amplitudes for the decays $K\to3\pi$ are calculated using Chiral Perturbation Theory. The calculation is made to next-to-leading order and includes full isospin breaking. The squared amplitudes are compared…
We use chiral perturbation theory to evaluate the scattering amplitude for the process Pi^+ K^- to Pi^+ K^- at leading and next-to-leading orders in the chiral counting and in the presence of isospin breaking effects. We also discuss the…
We compute the isospin susceptibility in an effective O($n$) scalar field theory (in $d=4$ dimensions), to third order in chiral perturbation theory ($\chi$PT) in the delta--regime using the quantum mechanical rotator picture. This is done…