XIIth Quark Confinement and the Hadron Spectrum

Effective field theories for muonic hydrogen

30 Aug 2016, 19:10

15m

Amfitrion I (Makedonia Palace)

Section E: QCD and New Physics Section E

Speaker

Clara Peset (UAB/IFAE)

Description

Experimental measurements of muonic hydrogen bound states have recently started to take place and provide a powerful setting in which to study the properties of QCD. We profit of the power of effective field theories (EFTs) to provide a theoretical setting in which to study muonic hydrogen in a model independent fashion. In particular, we compute expressions for the Lamb shift and the hyperfine splitting.

These expressions include the leading logarithmic $\mathcal{O}(m_{\mu }{\alpha }^6)$ terms, as well as the leading $\mathcal{O}(m_{\mu }{\alpha }^5\frac{m_{\mu }^2}{{\mathrm{\Lambda }}_{\text{Q}CD}^2})$ hadronic effects. Most remarkably, our analyses include the determination of the spin-dependent and spin-independent structure functions of the forward virtual-photon Compton tensor of the proton to $\mathcal{O}(p^3)$, using HBET and including the Delta particle. Using these results we obtain the leading hadronic contributions to the Wilson coefficients of the lepton-proton four fermion operators in NRQED. The spin-independent coefficient yields a pure prediction for the two-photon exchange contribution to the muonic hydrogen Lamb shift, which is the main source of uncertainty in our computation. The spin-dependent coefficient yields the prediction of the hyperfine splitting. The use of EFTs crucially helps us organizing the computation, in such a way that we can clearly address the parametric accuracy of our result. Furthermore, we review in the context of NRQED all the contributions to the energy shift of $\mathcal{O}(m_r{\alpha }^5)$, as well as those that scale like $m_r{\alpha }^6\times$ logarithms.

Presentation materials

Peset_QCHSXII_pNRQED.pdf