Nucleon sigma term and strange quark content from lattice QCD with exact chiral symmetry

100

We present the results of a third order calculation of the pion-nucleon scattering amplitude in a chiral effective field theory with pions, nucleons and delta resonances as explicit degrees of freedom. We work in a manifestly Lorentz invariant formulation of baryon chiral perturbation theory using dimensional regularization and the extended on-mass-shell renormalization scheme. In the delta resonance sector, the on mass-shell renormalization is realized as a complex-mass scheme. By fitting the low-energy constants of the effective Lagrangian to the S-and P -partial waves a satisfactory description of the phase shifts from the analysis of the Roy-Steiner equations is obtained. We predict the phase shifts for the D and F waves and compare them with the results of the analysis of the George Washington University group. The threshold parameters are calculated both in the delta-less and delta-full cases. Based on the determined low-energy constants, we discuss the pion-nucleon sigma term. Additionally, in order to determine the strangeness content of the nucleon, we calculate the octet baryon masses in the presence of decuplet resonances up to next-to-next-to-leading order in SU(3) baryon chiral perturbation theory. The octet baryon sigma terms are predicted as a byproduct of this calculation.

Section: Jhep05(2016)038 8 Summary and Conclusionmentioning

confidence: 56%

Pion-nucleon scattering in covariant baryon chiral perturbation theory with explicit Delta resonances

Yao

Siemens

Bernard

et al. 2016

100

“…In evaluating f Tq , we use the results from the lattice QCD simulation [35]: for m DM = m h /2 = 62.5 GeV.…”

Section: Jhep07(2017)048mentioning

confidence: 99%

Fermion dark matter in gauge-Higgs unification

Maru

Miyaji

Okada

et al. 2017

We propose a Majorana fermion dark matter in the context of a simple gaugeHiggs Unification (GHU) scenario based on the gauge group SU(3)×U(1) ′ in 5-dimensional Minkowski space with a compactification of the 5th dimension on S 1 /Z 2 orbifold. The dark matter particle is identified with the lightest mode in SU(3) triplet fermions additionally introduced in the 5-dimensional bulk. We find an allowed parameter region for the dark matter mass around a half of the Standard Model Higgs boson mass, which is consistent with the observed dark matter density and the constraint from the LUX 2016 result for the direct dark matter search. The entire allowed region will be covered by, for example, the LUX-ZEPLIN dark matter experiment in the near future. We also show that in the presence of the bulk SU(3) triplet fermions the 125 GeV Higgs boson mass is reproduced through the renormalization group evolution of Higgs quartic coupling with the compactification scale of around 10 8 GeV.

“…The value of σ πN relies on experimental data that is at present poorly known. The values which are widely used come mostly from lattice QCD and chiral perturbation theory calculations [67][68][69][70].…”

Section: Dark Matter Direct Detectionmentioning

confidence: 99%

Dark matter in the inert doublet model after the discovery of a Higgs-like boson at the LHC

Goudelis

Herrmann

Stål

2013

243

271

We examine the Inert Doublet Model in light of the discovery of a Higgs-like boson with a mass of roughly 126 GeV at the LHC. We evaluate one-loop corrections to the scalar masses and perform a numerical solution of the one-loop renormalization group equations. Demanding vacuum stability, perturbativity, and S-matrix unitarity, we compute the scale up to which the model can be extrapolated. From this we derive constraints on the model parameters in the presence of a 126 GeV Higgs boson. We perform an improved calculation of the dark matter relic density with the Higgs mass fixed to the measured value, taking into account the effects of three-and four-body final states resulting from off-shell production of gauge bosons in dark matter annihilation. Issues related to direct detection of dark matter are discussed, in particular the role of hadronic uncertainties. The predictions for the interesting decay mode h 0 → γγ are presented for scenarios which fulfill all model constraints, and we discuss how a potential enhancement of this rate from the charged inert scalar is related to the properties of dark matter in this model. We also apply LHC limits on Higgs boson decays to invisible final states, which provide additional constraints on the mass of the dark matter candidate. Finally, we propose three benchmark points that capture different aspects of the relevant phenomenology.