Search results for "Scattering amplitude"
showing 10 items of 170 documents
Ds0⁎±(2317)and KD scattering fromBs0decay
2015
We study the B¯s0→Ds−(KD)+ weak decay, and look at the KD invariant mass distribution, for which we use recent lattice QCD results for the KD interaction from where the Ds0⁎(2317) resonance appears as a KD bound state. Since there are not yet experimental data on this reaction, in a second step we propose an analysis method to obtain information on the Ds0⁎(2317) resonance from the future experimental KD mass distribution in this decay. For this purpose, we generate synthetic data taking a few points from our theoretical distribution, to which we add a 5% or 10% error. With this analysis method, we prove that one can obtain from these “data” the existence of a bound KD state, the KD scatter…
Pion-induced η production on nuclei
1990
Abstract Low-energy η production on nuclei is investigated in a DWIA framework, using a Green function method. The η potential is constructed by folding medium-modified η N → S 11 → η N scattering amplitudes with nuclear wave functions. A phenomenological spreading potential is introduced for the intermediate S 11 resonance. Calculated ( π + , p ) η cross sections on 12 C and 16 O with the spreading potential having an imaginary part of the order of −50 ∼ −100 MeV compare favorably with recent experimental data. It is also shown that the energy dependence of the ( π + , η ) inclusive spectra is nicely reproduced, though the magnitude is somewhat underestimated.
S=−1meson-baryon unitarized coupled channel chiral perturbation theory and theS01resonances Λ(1405) and -Λ(1670)
2003
The $s-$wave meson-baryon scattering is analyzed for the strangeness $S=-1$ and isospin I=0 sector in a Bethe-Salpeter coupled channel formalism incorporating Chiral Symmetry. Four channels have been considered: $\pi \Sigma$, $\bar K N$, $\eta \Lambda$ and $K \Xi$. The required input to solve the Bethe-Salpeter equation is taken from lowest order Chiral Perturbation Theory in a relativistic formalism. There appear undetermined low energy constants, as a consequence of the renormalization of the amplitudes, which are obtained from fits to the $\pi\Sigma\to\pi\Sigma$ mass-spectrum, to the elastic $\bar K N \to \bar K N$ and $ \bar K N\to \pi \Sigma$ $t$--matrices and to the $ K^- p \to \eta \…
Investigating the nature of light scalar mesons with semileptonic decays of D mesons
2015
We study the semileptonic decays of $D_{s}^{+}$, $D^{+}$, and $D^{0}$ mesons into the light scalar mesons [$f_{0} (500)$, $K_{0}^{\ast} (800)$, $f_{0} (980)$, and $a_{0}(980)$] and the light vector mesons [$\rho (770)$, $\omega (782)$, $K^{\ast} (892)$, and $\phi (1020)$]. With the help of a chiral unitarity approach in coupled channels, we compute the branching fractions for scalar meson processes of the semileptonic $D$ decays in a simple way. Using current known values of the branching fractions, we make predictions for the branching fractions of the semileptonic decay modes with other scalar and vector mesons. Furthermore, we calculate the $\pi ^{+} \pi ^{-}$, $\pi \eta$, $\pi K$, and $…
Chiral symmetry andπ-πscattering in the covariant spectator theory
2014
The π-π scattering amplitude calculated with a model for the quark-antiquark interaction in the framework of the Covariant Spectator Theory (CST) is shown to satisfy the Adler zero constraint imposed by chiral symmetry. The CST formalism is established in Minkowski space and our calculations are performed in momentum space. We prove that the axial-vector Ward-Takahashi identity is satisfied by our model. Then we show that, similarly to what happens within the Bethe-Salpeter formalism, application of the axial-vector Ward Takahashi identity to the CST π-π scattering amplitude allows us to sum the intermediate quark-quark interactions to all orders. Thus, the Adler self-consistency zero for π…
Forward light-by-light scattering and electromagnetic correction to hadronic vacuum polarization
2023
Lattice QCD calculations of the hadronic vacuum polarization (HVP) have reached a precision where the electromagnetic (e.m.) correction can no longer be neglected. This correction is both computationally challenging and hard to validate, as it leads to ultraviolet (UV) divergences and to sizeable infrared (IR) effects associated with the massless photon. While we precisely determine the UV divergence using the operator-product expansion, we propose to introduce a separation scale $\Lambda\sim400\;$MeV into the internal photon propagator, whereby the calculation splits into a short-distance part, regulated in the UV by the lattice and in the IR by the scale $\Lambda$, and a UV-finite long-di…
On the mathematical properties of multi-loop scattering amplitudes through the loop-tree duality
2023
El asombroso desarrollo de los experimentos de física de altas energías, como el Gran Colisionador de Hadrones del CERN, ha permitido obtener datos de gran calidad. El interés por comprender estos datos ha dado lugar a la necesidad de aumentar la precisión de las predicciones teóricas correspondientes. En esta tesis se desarrolla desde sus fundamentos matemáticos un método enfocado en cálculos de alta precisión denominado Loop-Tree Duality (dualidad lazo-árbol). Presentamos una clasificación de los diagramas de Feynman con respecto a su topología más que en el número de loops, en donde todas las clases topológicas pueden tener un número arbitrario L de loops y que se distinguen en su topolo…
From a causal representation of multiloop scattering amplitudes to quantum computing in the Loop-Tree Duality
2023
La teoría cúantica de campos con enfoque perturbativo ha logrado de manera exitosa proporcionar predicciones teóricas increíblemente precisas en física de altas energías. A pesar del desarrollo de diversas técnicas con el objetivo de incrementar la eficiencia de estos cálculos, algunos ingredientes continuan siendo un verdadero reto. Este es el caso de las amplitudes de dispersión con lazos múltiples, las cuales describen las fluctuaciones cuánticas en los procesos de dispersión a altas energías. La Dualidad Lazo-Árbol (LTD) es un método innovador, propuesto con el objetivo de afrontar estas dificultades abriendo las amplitudes de lazo a amplitudes conectadas de tipo árbol. En esta tesis pr…
Fixed Angle Inverse Scattering for Almost Symmetric or Controlled Perturbations
2020
We consider the fixed angle inverse scattering problem and show that a compactly supported potential is uniquely determined by its scattering amplitude for two opposite fixed angles. We also show that almost symmetric or horizontally controlled potentials are uniquely determined by their fixed angle scattering data. This is done by establishing an equivalence between the frequency domain and the time domain formulations of the problem, and by solving the time domain problem by extending the methods of [RS19] which adapts the ideas introduced in [BK81] and [IY01] on the use of Carleman estimates for inverse problems.
Scattering of Co-Current Surface Waves on an Analogue Black Hole
2018
We report on what is to our knowledge the first scattering experiment of surface waves on an accelerating transcritical flow, which in the analogue gravity context is described by an effective spacetime with a black-hole horizon. This spacetime has been probed by an incident co-current wave, which partially scatters into an outgoing countercurrent wave on each side of the horizon. The measured scattering amplitudes are compatible with the predictions of the hydrodynamical theory, where the kinematical description in terms of the effective metric is exact.