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We develop a method for lattice QCD calculation of the two-photon exchange contribution to the muonic-hydrogen Lamb shift. To demonstrate its feasibility, we present the first lattice calculation with a gauge ensemble at m_{π}=142 MeV. By adopting the infinite-volume reconstruction method along with an optimized subtraction scheme, we obtain with statistical uncertainty ΔE_{TPE}=-28.9(4.9) μeV+93.72 μeV/fm^{2}·⟨r_{p}^{2}⟩, or ΔE_{TPE}=37.4(4.9) μeV, which is consistent with the previous theoretical results in a range of 20-50 μeV.
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http://dx.doi.org/10.1103/PhysRevLett.128.172002 | DOI Listing |
Phys Rev Lett
July 2025
Carnegie Mellon University, Department of Physics, Pittsburgh, Pennsylvania 15213, USA.
We use lattice QCD calculations of the finite-volume spectra of systems of two and three mesons to determine, for the first time, three-particle scattering amplitudes with physical quark masses. Our results are for combinations of π^{+} and K^{+}, at a lattice spacing a=0.063 fm, and in the isospin-symmetric limit.
View Article and Find Full Text PDFPhys Rev Lett
July 2025
Homi Bhabha National Institute, The Institute of Mathematical Sciences, a CI of , Chennai, 600113, India.
We calculate the spatial Wilson line correlator for 2+1 flavor QCD using highly improved staggered quark discretization for fermions and in quenched QCD for a wide range of temperatures, from the chiral crossover temperature T_{pc}≃156 MeV or the deconfinement temperature ≃300 MeV, respectively, up to 2 GeV. Extracting the spatial string tension for different lattice cutoffs and by performing a continuum extrapolation of this observable, we show that the soft (magnetic) gluons interact nonperturbatively even at temperatures ≳1 GeV. We provide incriminating evidences to demonstrate that dimensionally reduced effective theories can describe these soft quark and gluon quasi-particles for both quenched and 2+1 flavor QCD, at temperatures T≳5T_{pc}.
View Article and Find Full Text PDFPhys Rev Lett
July 2025
University of Utah, Department of Physics and Astronomy, Salt Lake City, Utah 84112, USA.
We present results for the dominant light-quark connected contribution to the long-distance window of the hadronic vacuum polarization (HVP) contribution to the muon g-2 from lattice quantum chromodynamics. Specifically, with a new determination of the lattice scale on MILC's physical-mass HISQ ensembles, using the Ω^{-} baryon mass, we obtain a result of a_{μ}^{ll,LD}(conn)=400.2(2.
View Article and Find Full Text PDFPhys Rev Lett
June 2025
Peking University, School of Physics, Peking University, Beijing 100871, China and Center for High Energy Physics, Beijing 100871, China.
We present the first complete next-to-next-to-next-to-leading-order calculation of the matching coefficients that link unpolarized flavor nonsinglet parton distribution functions with lattice QCD computable correlation functions. By using this high-order result, we notice a reduction in theoretical uncertainties compared to relying solely on previously known lower-order matching coefficients. Furthermore, based on this result we have extracted the three-loop unpolarized flavor nonsinglet splitting function, which is in agreement with the state-of-the-art result.
View Article and Find Full Text PDFPhys Rev Lett
June 2025
University of California, Berkeley, Berkeley Center for Theoretical Physics, California 94720, USA.
The quantum chromodynamics (QCD) axion arises as the pseudo-Goldstone mode of a spontaneously broken Abelian Peccei-Quinn (PQ) symmetry. If the scale of PQ symmetry breaking occurs below the inflationary reheat temperature and the domain wall number is unity, then there is a unique axion mass that gives the observed dark matter (DM) abundance. Computing this mass has been the subject of intensive numerical simulations for decades since the mass prediction informs laboratory experiments.
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