arXiv subjects

Bastian Knippschild

Publications and source records attributed to Bastian Knippschild.

25 records · Page 2Linked to original sources

arXiv2013

The phase structure of a chirally-invariant Higgs-Yukawa model

We present new results of our ongoing project on the investigation of the phase structure of the Higgs-Yukawa model at small and large bare Yukawa couplings. The critical exponents of the second order bulk phase transitions of this model are determined from finite-size analyses and compared to the pure O(4)-model to test for triviality and the possibility of having a non-Gaussian fixed point. In addition, we will present a first study of Higgs boson masses and fermion correlation functions.

hep-lat↗

arXiv2013

Higgs-Yukawa model in chirally-invariant lattice field theory

Non-perturbative numerical lattice studies of the Higgs-Yukawa sector of the standard model with exact chiral symmetry are reviewed. In particular, we discuss bounds on the Higgs boson mass at the standard model top quark mass, and in the presence of heavy fermions. We present a comprehensive study of the phase structure of the theory at weak and very strong values of the Yukawa coupling as well as at non-zero temperature.

hep-lat↗

arXiv2012

Excited state systematics in extracting nucleon electromagnetic form factors

We present updated preliminary results for the nucleon electromagnetic form factors for non-perturbatively $\mathcal{O}(a)$ improved Wilson fermions in $N_f=2$ QCD measured on the CLS ensembles. The use of the summed operator insertion method allows us to suppress the influence of excited states in our measurements. A study of the effect that excited state contaminations have on the $Q^2$ dependence of the extracted nucleon form factors may then be made through comparisons of the summation method to standard plateau fits, as well as to excited state fits.

hep-lat↗

arXiv2012

Investigation of the phase structure of a chirally-invariant Higgs-Yukawa model

We present new data on our ongoing project on the investigation of the phase structure of the Higgs-Yukawa model at large bare Yukawa couplings. The data presented last year are extended in terms of statistics, the number of bare Yukawa couplings at existing, and new larger volumes. In addition, this study is extended by a finite temperature project at the physical top quark mass m_t =175 GeV and a hypothetical fourth generation top quark with a mass of m_t' =700 GeV .

hep-lat↗

arXiv2011

Study of the Higgs-Yukawa theory in the strong-Yukawa coupling regime

In this article, we present an ongoing lattice study of the Higgs-Yukawa model, in the regime of strong-Yukawa coupling, using overlap fermions. We investigated the phase structure in this regime by computing the Higgs vacuum expectation value, and by exploring the finite-size scaling behaviour of the susceptibility corresponding to the magnetisation. Our preliminary results indicate the existence of a second-order phase transition when the Yukawa coupling becomes large enough, at which the Higgs vacuum expectation value vanishes and the susceptibility diverges.

hep-lat↗

arXiv2011

Scale setting via the Ω baryon mass

We present the first results of an ongoing effort to determine the lattice scale on the N_f=2 CLS lattice ensembles via the mass of the Ω baryon. Results from different methods are compared, and various sources of systematic uncertainty are discussed.

hep-lat↗

arXiv2010

Systematic errors in extracting nucleon properties from lattice QCD

Form factors of the nucleon have been extracted from experiment with high precision. However, lattice calculations have failed so far to reproduce the observed dependence of form factors on the momentum transfer. We have embarked on a program to thoroughly investigate systematic effects in lattice calculation of the required three-point correlation functions. Here we focus on the possible contamination from higher excited states and present a method which is designed to suppress them. Its effectiveness is tested for several baryonic matrix elements, different lattice sizes and pion masses.

hep-lat↗