Related papers: Extracting the chiral anomaly from gamma pi --> pi…
The three precision measurements of the cross section $\sigma\big(e^+e^-\rightarrow\pi^+\pi^-\gamma(\gamma)\big)$ using initial state radiation by the KLOE collaboration provide an important input for the prediction of the hadronic…
We have computed the hadronic light-by-light (LbL) contribution to the muon anomalous magnetic moment $a_\mu$ in the frame of Chiral Perturbation Theory with the inclusion of the lightest resonance multiplets as dynamical fields (R$\chi$T).…
The process $e^+e^-\to \pi^+\pi^-\pi^0\gamma$ is studied at a center-of-mass energy near the $\Upsilon(4S)$ resonance using a data sample of 469 fb$^{-1}$ collected with the BABAR detector at the PEP-II collider. We have performed a precise…
The near-threshold n p -> d pi0 cross section is calculated in chiral perturbation theory to next-to-leading order in the expansion parameter sqrt{M m_pi}/Lambda_chi. At this order irreducible pion loops contribute to the relevant…
The role of the contribution from the fermion mass term in the axial vector Ward identity in generating the U(1) axial anomaly, both local and global, is elucidated. Gauge invariance requires the fermion to decouple from the gauge field if…
Differential cross sections for pi- p and pi+ p elastic scattering were measured at five energies between 19.9 and 43.3 MeV. The use of the CHAOS magnetic spectrometer at TRIUMF, supplemented by a range telescope for muon background…
The KLOE Experiment at the $\phi$ factory DA$\Phi$NE, has measured the cross section $\sigma(e^+e^-\to\pi^+\pi^-\gamma)$ using two different selection schemes: requiring the photon emission at small polar angle and detecting the photon at…
The current status of the muon anomalous magnetic moment (AMM) problem is briefly presented. The corrections to the muon AMM coming from the effects of hadronic light-by-light (LbL) scattering due to light quark-antiquark exchange in…
An implicit four dimensional regularization is applied to calculate the axial-vector-vector anomalous amplitude. The present technique always complies with results of Dimensional Regularization and can be easily applied to processes…
The BABAR experiment participates to the global endeavor for a precise prediction of the anomalous magnetic moment of the muon by evaluating the contribution of hadronic processes to the vacuum polarization. After its last result published…
We have measured the differential cross section for the gamma n --> pi- p and gamma p --> pi+ n reactions at center of mass angle of 90 degree in the photon energy range from 1.1 to 5.5 GeV at Jefferson Lab (JLab). The data at photon…
Dirac and Weyl semimetals form an ideal platform for testing ideas developed in high energy physics to describe massless relativistic particles. One such quintessentially field-theoretic idea of chiral anomaly already resulted in the…
Two new hadronic cross sections measured by the BaBar experiment are presented: $e^+e^- \to \pi^+\pi^-\pi^0\pi^0$ and $e^+e^- \to \pi^+\pi^-\eta$. For both channels, the contribution the anomalous magnetic moment of the muon is calculated.
We have previously analysed the chiral predictions for the decay K_L -> pi0 gamma e+ e- and discussed how experimental measurements of this process can help our understanding of chiral theories and of CP tests. Motivated by the possibility…
We evaluate the pion_0 into two gammas decay amplitude by an effective action derived from QCD in the quark composites approach, getting the standard value. We also verify that our effective action correctly reproduces the chiral anomaly.
We discuss $\pi\pi$ scattering in the framework of chiral perturbation theory. In particular, we recall the predictions made some time ago for the threshold parameters and for the phase shift difference $\delta_0^0-\delta_1^1$.
The results of analyses obtained in Part I are examined from the viewpoint of chiral symmetry. The mass spectra of pi pi system are widely believed to be suppressed generally near the threshold, because of the derivative coupling property…
The axial anomaly in a quasi-one-dimensional (quasi-1D) chiral p-wave superfluid model, which has a epsilon_{x} p_{x}+i epsilon_{y} p_{y}-wave gap in 2D is studied. The anomaly causes an accumulation of the quasiparticle and a quantized…
We have measured the ratio $\sigma(e^+e^-\rightarrow\pi^+\pi^-\gamma)/\sigma(e^+e^-\rightarrow \mu^+\mu^-\gamma)$, with the KLOE detector at DA$\Phi$NE for a total integrated luminosity of $\sim$ 240 pb$^{-1}$. From this ratio we obtain the…
The differential cross section for the gamma +n --> pi- + p and the gamma + p --> pi+ n processes were measured at Jefferson Lab. The photon energies ranged from 1.1 to 5.5 GeV, corresponding to center-of-mass energies from 1.7 to 3.4 GeV.…