相关论文: Regge analysis of the pi pi scattering amplitude
Our results on obtaining the Regge trajectory of a resonance from its pole in a scattering process and from analytic constraints in the complex angular momentum plane are presented. The method, suited for resonances that dominate an elastic…
We review the basic assumptions and spell out the detailed arguments that lead to the bound on the Regge growth of gravitational scattering amplitudes. The minimal extra ingredient compared to the gapped case - in addition to unitarity,…
In a previous paper, some deviations were found in the O(p^6) low-energy constants that contribute to the pi pi-scattering lengths. This work completes the study of all the relevant couplings (r_1, ... r_6, r_S2). We also perform a…
We present a detailed analysis of S-wave Kpi scattering up to 2 GeV, making use of the resonance chiral Lagrangian predictions together with a suitable unitarisation method. Our approach incorporates known theoretical constraints at low and…
Roy's equations are used to check if the scalar-isoscalar pion-pion scattering amplitudes fitted to experimental data fulfill crossing symmetry conditions. It is shown that the amplitudes describing the ``down-flat'' phase shift solution…
We study the high-energy small-angle {\it Regge} limit of the fermion-antifermion scattering in gauge theories and consider the part of the amplitude suppressed by a power of the scattering angle. For abelian gauge group all-order…
The Khuri-Treiman formalism models the partial-wave expansion of a scattering amplitude as a sum of three individual truncated series, capturing the low-energy dynamics of the direct and cross channels. We cast this formalism into…
Starting from hyperbolic dispersion relations, we derive a closed system of Roy-Steiner equations for pion-nucleon scattering that respects analyticity, unitarity, and crossing symmetry. We work out analytically all kernel functions and…
We present technical details of the evaluation of the elastic pi-pi scattering amplitude to two loops in chiral perturbation theory. In particular, we elaborate on the renormalization procedure at the two-loop order and on the evaluation of…
Recent work in low energy pion physics is reviewed. One of the exciting new developments in this field is that simulations of QCD on a lattice now start providing information about the low energy structure of the continuum theory, for…
A partial wave analysis of the centrally produced pi+pi- channel has been performed in pp collisions using an incident beam momentum of 450 GeV/c. An unambiguous physical solution has been found. Evidence is found for the f0(980), f0(1300),…
We consider the Olsson sum rule, i.e., the forward dispersion relation for pion-pion scattering with exchange of isospin unity at threshold. We show that, if using the S0, S2 and P wave expressions of Colangelo, Gasser and Leutwyler, then…
The experimental results obtained in the last few years on kaon decays (K$\to2\pi$ and, above all, Ke4 decays) allow a reliable, model independent determination of low energy $\pi\pi$ scattering in the S0 wave. Using them and, eventually,…
The Regge limit of gauge-theory amplitudes and cross sections is a powerful theory tool for the study of fundamental interactions. It is a vast field of research, encompassing perturbative and non-perturbative dynamics, and ranging from…
A correct understanding and description of the I=2 pi-pi S-wave interaction is important for the extraction of the I=0 pi-pi S-wave interaction from experimental data and for understanding the I=0 pi-pi S-wave interaction theoretically.…
We present a data-driven analysis of the S-wave $\pi\pi \to \pi\pi\,(I=0,2)$ and $\pi K \to \pi K\,(I=1/2, 3/2)$ reactions using the partial-wave dispersion relation. The contributions from the left-hand cuts are parametrized using the…
In this talk I summarize a recently proposed mechanism to understand pi pi scattering to 1 GeV. The model is motivated by the 1/Nc expansion to QCD, and includes a current algebra contact term and resonant pole exchanges. Chiral symmetry…
We review our analysis of $\pi K$ scattering using forward dispersion relations. The method yields a set of simple parameterizations that are compatible with forward dispersion relations up to 1.6 GeV while still describing the data. Once…
A Regge model with absorptive corrections is employed in a global analysis of the world data on positive and negative pion photoproduction for photon energies from 3 to 8 GeV. In this region resonance contributions are expected to be…
A Regge model with absorptive corrections is employed in a global analysis of the world data on the reactions gamma p -> pi0 p and gamma n -> pi0 n for photon energies from 3 to 18 GeV. In this region resonance contributions are expected to…