20190314 15:26 
[PUBDB201901546]
Preprint/Report
Caselle, M. ; Nada, A. ; Panero, M. ; et al
Conformal field theory and the hot phase of threedimensional U(1) gauge theory
[arXiv:1903.00491; DESY19027]
We study the hightemperature phase of compact U(1) gauge theory in 2+1 dimensions, comparing the results of lattice calculations with analytical predictions from the conformalfieldtheory description of the lowtemperature phase of the bidimensional XY model. We focus on the twopoint correlation functions of probe charges and the fieldstrength operator, finding excellent quantitative agreement with the functional form and the continuously varying critical indices predicted by conformal field theory..
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20190219 13:14 
[PUBDB201901169]
Report/Journal Article
Garcia Vera, M. F. ; Sommer, R.
Large $N$ scaling and factorization in SU($N$) YangMills gauge theory
[DESY18075; arXiv:1805.11070]
The large $N$ limit of SU($N$) gauge theories is well understood in perturbation theory. Also nonperturbative lattice studies have yielded important positive evidence that t Hoofts predictions are valid. [...]
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ddc:530
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20190211 09:44 
[PUBDB201901028]
Journal Article
Gérardin, A. ; Harris, T. ; Meyer, H. B.
Nonperturbative renormalization and $O(a )$improvement of the nonsinglet vector current with $N_f = 2 + 1$ Wilson fermions and treelevel Symanzik improved gauge action
In calculating hadronic contributions to precision observables for tests of the Standard Model in lattice QCD, the electromagnetic current plays a central role. Using a Wilson action with $O(a)$ improvement in QCD with $N_ f$ flavors, a counterterm must be added to the vector current in order for its onshell matrix elements to be $O(a)$ improved. [...]
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ddc:530
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20190129 10:01 
[PUBDB201900846]
Report/Journal Article
Carmignotto, M. ; Ali, S. ; Aniol, K. ; et al
Separated Kaon Electroproduction Cross Section and the Kaon Form Factor from 6 GeV JLab Data
[JLABPHY182645; arXiv:1801.01536]
The H1(e,e′K+)Λ reaction was studied as a function of the Mandelstam variable −t using data from the E01004 (FPI2) and E93018 experiments that were carried out in Hall C at the 6 GeV Jefferson Laboratory. The cross section was fully separated into longitudinal and transverse components, and two interference terms at fourmomentum transfers Q2 of 1.00, 1.36, and 2.07GeV2. [...]
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20190116 11:53 
[PUBDB201900523]
Report/Contribution to a conference proceedings
Green, J.
Systematics in nucleon matrix element calculations
[DESY18224, arXiv:1812.10574]
201836th International Symposium on Lattice Field Theory, LATTICE 2018, East LansingEast Lansing, USA, 22 Jul 2018  28 Jul 20182018072220180728
15 pp. (2018) [10.3204/PUBDB201900523]2018
The current status of calculations of simple nucleon structure observables is reviewed, with a focus on the axial charge. A major challenge is the combination of an exponentially decaying signaltonoise ratio and the need for large sourcesink separations to eliminate excitedstate contributions; efforts to understand and deal with this problem are the focus of the largest section of this review. [...]
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20190114 15:08 
[PUBDB201900443]
Preprint/Report
Alexandrou, C. ; Bacchio, S. ; Constantinou, M. ; et al
Proton and neutron electromagnetic form factors from lattice QCD
[arXiv:1812.10311; DESY18033]
The electromagnetic form factors of the proton and the neutron are computed within lattice QCD using simulations of maximally twisted mass fermions with masses fixed to their physical values. We analyse two new ensembles of $N_f=2$ and $N_f=2+1+1$ and use several values of the sinksource time separation in the range of 1.0 fm to 1.6 fm to ensure ground state identification. [...]
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20190103 15:05 
[PUBDB201900034]
Report/Journal Article
Green, J. ; Jansen, K. ; Steffens, F.
Nonperturbative Renormalization of Nonlocal Quark Bilinears for Parton Quasidistribution Functions on the Lattice Using an Auxiliary Field
[DESY17109; arXiv:1707.07152]
QuasiPDFs provide a path toward an ab initio calculation of parton distribution functions (PDFs) using lattice QCD. One of the problems faced in calculations of quasiPDFs is the renormalization of a nonlocal operator. [...]
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20190103 11:25 
[PUBDB201900019]
Journal Article/Report/Contribution to a conference proceedings
Asmussen, N. ; Gérardin, A. ; Green, J. ; et al
Hadronic lightbylight scattering contribution to the muon $g2$ on the lattice
[DESY18007; MITP18001; arXiv:1801.04238]
We briefly review several activities at Mainz related to hadronic lightbylight scattering (HLbL) using lattice QCD. First we present a positionspace approach to the HLbL contribution in the muon g2, where we focus on exploratory studies of the pionpole contribution in a simple model and the lepton loop in QED in the continuum and in infinite volume. [...]
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20190103 11:18 
[PUBDB201900018]
Journal Article/Report/Contribution to a conference proceedings
Alexandrou, C. ; Constantinou, M. ; Hadjiyiannakou, K. ; et al
Connected and disconnected contributions to nucleon axial form factors using $\mathrm{N_f = 2}$ twisted mass fermions at the physical point
[arXiv:1807.11203]
We present results on the isovector and isoscalar nucleon axial form factors including disconnected contributions, using an ensemble of N$_f$ = 2 twisted mass cloverimproved Wilson fermions simulated with approximately the physical value of the pion mass. The light disconnected quark loops are computed using exact deflation, while the strange and the charm quark loops are evaluated using the truncated solver method. [...]
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20190103 11:12 
[PUBDB201900017]
Journal Article/Report/Contribution to a conference proceedings
Alexandrou, C. ; Constantinou, M. ; Hadjiyiannakou, K. ; et al
Nucleon spin structure from lattice QCD
[arXiv:1807.11214]
In this lattice QCD study we evaluate the nucleon spin decomposition to quarks and gluons contributions. We employ one gauge ensemble of maximally twisted mass fermions with two degenerate light quarks tuned to approximately reproduce the physical pion mass [...]
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