### Conveners

#### Parallel Session 2 - Goldstone Boson WG

- Mario Antonelli (LNF)
- Sebastien Descotes-Genon (CNRS/Univ. Paris-Sud 11)
- Andreas Juettner (University of Southampton)
- Emilie Passemar (Indiana University/JLab)

Peter Stoffer
(HISKP, University of Bonn)

6/29/15, 4:20 PM

Goldstone Boson Working Group

Talk

K_{l4} decays have several features of interest: they allow an accurate measurement of ππ-scattering lengths; the decay is the best source for the determination of some low-energy constants of chiral perturbation theory (χPT); one form factor of the decay is connected to the chiral anomaly. We present the final results of our dispersive analysis of K_{l4} decays, which provides a resummation...

Xian-Wei Kang
(IAS and IKP, Forschungszentrum Jülich)

6/29/15, 4:40 PM

Goldstone Boson Working Group

Talk

The Cabibbo-Kobayashi-Maskawa matrix element |Vub| is not well determined yet. It can be extracted from both inclusive or exclusive decays, like B → ρ(π)l¯νl. However, the exclusive determination from B → ρl¯νl, in particular, suffers from a large model dependence. In this talk, I will elaborate our proposal [1]: extracting |Vub| from the four- body semileptonic decay B → ππl¯νl, where the...

Balasubramanian Ananthanarayan
(Indian Institute of Science, Bengaluru)

6/29/15, 5:00 PM

Goldstone Boson Working Group

Talk

Motivated by the discrepancies noted recently between the theoretical calculations of the electromagnetic ωπ form factor and certain experimental data, we investigate this form factor using analyticity and unitarity in a framework known as the method of unitarity bounds. We use a QCD correlator computed on the spacelike axis by operator product expansion and perturbative QCD as input, and...

Tadeusz Janowski
(University of Southampton)

6/29/15, 5:20 PM

Goldstone Boson Working Group

Talk

We present the recent lattice QCD calculation of K-π I=3/2 and I=1/2 scattering lengths by the RBC-UKQCD collaboration. Our calculation is the first lattice calculation of these quantities performed using physical point ensembles [1]. This allows us to bypass the error due to chiral extrapolation, which in current calculations is the dominant source of systematic errors [2,3,4,5]. Preliminary...

Thomas Rössler
(Lund University)

6/29/15, 5:40 PM

Goldstone Boson Working Group

Talk

The talk will cover the recent progress in Chiral Perturbation Theory at two-loop order in finite volume. The techniques used in the two-loop finite volume integrals [1] will be described shortly and afterwards applications to masses and decay constants both for the standard case in two and three flavours [2] and partially quenched for three sea quark flavours [3] will be discussed.
[1]...

Johan Relefors
(Lund University)

6/29/15, 6:00 PM

Goldstone Boson Working Group

Talk

The talk will describe the recent work at one-loop Chiral perturbation Theory with twisted boundary conditions [1]. We point out that due to the broken Lorentz and reflection symmetry a number of new terms show up in the expressions. The pseudo-scalar octet masses, axial-vector and pseudo-scalar decay constants and electromagnetic form-factors will be discussed explicitly. We show how the...