Low energy structure of the nucleon from chiral effective field theory

Jose Manuel Alarcón

doi:10.1051/epjconf/20148105002

Abstract

We present some updated results regarding the scalar and electromagnetic structure of the nucleon obtained by the relativistic formulation of chiral effective field theory with baryons. We compare them with previous determinations available in the literature, and show their relevance for searches of physics beyond the standard model in the low energy frontier. An accurate knowledge of the structure of the nucleon is important to improve our understanding of the funda- mental interactions and provide theoretical estimations of some important quantities with a small uncertainty. This is specially relevant for experiential searches of physics be- yond the standard model in the low energy frontier. The electromagnetic structure of the nucleon is a good exam- ple, since its impact in the muonic hydrogen Lamb shift has the potential to solve the so-called proton radius puz- zle. In fact, this has motivated many theoretical works (1-10). Also, a good understanding of the scalar struc- ture of the nucleon is required to answer many important questions, as the origin of the mass of the ordinary matter, or to learn how different fundamental elements needed for life appear in nature (11). Nowadays, an accurate knowl- edge of the scalar structure of the nucleon is also impor- tant in dark matter (DM) detection, since the different re- sults regarding its scalar coupling is the main hadronic un- certainty in the estimation of the spin-independent DM- nucleon elastic scattering cross sections (12-14). These properties mentioned above are governed by the strong interaction, described by the quantum chromo dy- namics (QCD). Unfortunately, QCD does not allow a per- turbative treatment in the low energy region, which is the region of interest here. Fortunately, one can always con- struct an effective field theory (EFT) containing the sym- metries of QCD and its relevant degrees of freedom to apply perturbative techniques. This approach exists since long time ago and is called chiral effective field theory. In this contribution I will present some recent results concerning the study of the scalar and electromagnetic structure of the nucleon in the relativistic formulation of chiral EFT with baryons. The main difference with re- spect to the other versions of chiral EFT with baryons (i. e. Heavy Baryon (HB) (15) and Infrared Regularization

Highlights

An accurate knowledge of the structure of the nucleon is important to improve our understanding of the fundamental interactions and provide theoretical estimations of some important quantities with a small uncertainty
The properties of the nucleons at low energies are relevant for experimental searches of physics beyond the standard model
They can be accessed through an effective field theory, like chiral EFT, containing the symmetries of quantum chromo dynamics (QCD) relevant for the energies of interest

Summary

Introduction

An accurate knowledge of the structure of the nucleon is important to improve our understanding of the fundamental interactions and provide theoretical estimations of some important quantities with a small uncertainty. An accurate knowledge of the scalar structure of the nucleon is important in dark matter (DM) detection, since the different results regarding its scalar coupling is the main hadronic uncertainty in the estimation of the spin-independent DMnucleon elastic scattering cross sections [12,13,14]. These properties mentioned above are governed by the strong interaction, described by the quantum chromo dynamics (QCD). This approach exists since long time ago and is called chiral effective field theory

Scalar Structure of the Nucleon

Electromagnetic Structure of the Nucleon

Conclusions