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- Marc Knecht
- 1994

The Generalized Chiral Perturbation Theory enlarges the framework of the standard χPT, relaxing certain assumptions which do not necessarily follow from QCD or from experiment, and which are crucial for the usual formulation of the low energy expansion. In this way, the experimental tests of the foundations of the standard χPT become possible. Emphasize is… (More)

- Marc Knecht, Res URECH
- 1998

The low energy scattering of pions is investigated in the presence of electromagnetic interactions at leading order and at next-to-leading order for the amplitudes involving at most one pair of charged pions. The size of the electromagnetic corrections to the S-wave scattering lengths is found to be comparable to the size of the two loop strong interaction… (More)

We construct a low-energy effective field theory which allows the full treatment of isospinbreaking effects in semileptonic weak interactions. To this end, we enlarge the particle spectrum of chiral perturbation theory with virtual photons by including also the light leptons as dynamical degrees of freedom. Using super-heat-kernel techniques, we determine… (More)

- Marc Knecht, Eduardo de Rafael
- 2001

We compare recent theoretical determinations of weak matrix elements of the electroweak penguin operators Q7 and Q8. We pay special attention to the renormalization scheme dependence of these determinations as well as to the influence of higher dimension operators in the different approaches.

- R. Aaij, C. Abellán Beteta, +497 authors Olena Shevchenko
- 2012

The production of Υ (1S), Υ (2S) and Υ (3S) mesons in proton-proton collisions at the centre-of-mass energy of √ s = 7 TeV is studied with the LHCb detector. The analysis is based on a data sample of 25 pb−1 collected at the Large Hadron Collider. The Υ mesons are reconstructed in the decay mode Υ → μ+μ− and the signal yields are extracted from a fit to the… (More)

The low-energy ππ amplitude is computed explicitly to two-loop accuracy in the chiral expansion. It depends only on six independent (combinations of) low-energy constants which are not fixed by chiral symmetry. Four of these constants are determined via sum rules which are evaluated using ππ scattering data at higher energies. Dependence of the low-energy… (More)

- Matthew T Dickerson, Morgan B. Abney, Caroline E. Cameron, Marc Knecht, Leonidas G. Bachas, Kimberly Ward Anderson
- Bioconjugate chemistry
- 2012

Past work has shown that Treponema pallidum, the causative agent of syphilis, binds host fibronectin (FN). FN and other host proteins are believed to bind to rare outer membrane proteins (OMPs) of T. pallidum, and it is postulated that this interaction may facilitate cell attachment and mask antigenic targets on the surface. This research seeks to prepare a… (More)

- R. Aaij, C. Abellán Beteta, +497 authors Olena Shevchenko
- 2012

The differential cross-section for the inclusive production of ψ(2S) mesons in pp collisions at √ s = 7 TeV has been measured with the LHCb detector. The data sample corresponds to an integrated luminosity of 36 pb−1. The ψ(2S) mesons are reconstructed in the decay channels ψ(2S) → μ+μ− and ψ(2S) → J/ψπ+π−, with the J/ψ meson decaying into two muons.… (More)

Starting from the study of the low-energy and high-energy behaviours of the QCD three-point functions 〈VAP 〉, 〈V VP 〉 and 〈AAP 〉, several O(p6) low-energy constants of the chiral Lagrangian are evaluated within the framework of the lowest meson dominance (LMD) approximation to the large-NC limit of QCD. In certain cases, values that differ substantially… (More)

- Marc Knecht, Eduardo de Rafael
- 1998

It is shown that in vector–like gauge theories, such as QCD, and in the limit of a large number of colours Nc, the ordering pattern of narrow vector and axial–vector states at low energies is correlated with the size of the possible local order parameters of chiral symmetry breaking. This has implications on the underlying dynamics of spontaneous chiral… (More)