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Lattice QCD

Lattice QCD at Non-vanishing Baryon Chemical Potential: Taylor Expansion, Yang-Lee Singularity and Resummation

After introducing the Taylor expansion method for lattice QCD calculations at non-vanishing baryon chemical potential, I will scrutinize the limitations of the method arising from the presence of Yang-Lee edge singularities in the QCD phase diagram. I will discuss a newly introduced resummation scheme for the Taylor expansion to overcome this limitation and show the efficacy of this scheme using a simple solvable model. I will present some results from realistic lattice QCD calculations utilizing this resummation scheme. I will conclude by introducing a generalized version of the scheme that can resum the recently proposed multi-parameter Taylor expansion. 

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Status of first-principles lattice QCD+QED calculations of the hadronic contributions to the muon g-2

I will summarize the current status of lattice QCD+QED calculations of the hadronic light-by-light and hadronic vacuum polarization (HVP) contributions to the muon g-2.  Special attention will be given to the consistency of different lattice HVP and dispersive HVP results.  I will conclude with an outlook of what we can expect from the field in the near future.

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Strange and Charm Parton Distribution Function (PDF) from Lattice QCD

We present the first lattice-QCD calculation of the unpolarized strange and charm parton distribution functions using large-momentum effective theory (LaMET). We use a lattice ensemble with 2+1+1 flavors of highly improved staggered quarks (HISQ) generated by MILC collaboration, with lattice spacing a ≈ 0.12 fm and Mπ ≈ 310 MeV, and clover valence fermions with two valence pion masses: 310 and 690 MeV. We use momentum-smeared sources to improve the signal up to nucleon boost momentum Pz = 2.18 GeV,  and determine nonperturbative renormalization factors in RI/MOM scheme. We compare our lattice results with the matrix elements obtained from matching the PDFs from CT18NNLO and NNPDF3.1NNLO global fits. Our data support the assumptions of strange-antistrange and charm-anticharm symmetry that are commonly used in global PDF fits.

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