National Energy Research Scientific Computing Center 2004 Annual Report
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high energy physics
Twisted Mass Lattice QCD
S. R. Sharpe and J. M. S. Wu, “Phase diagram of twisted mass lattice QCD,” Phys. Rev. D 70, 094029 (2004). HEP
There has been considerable interest recently in the twisted mass formulation of lattice QCD, which has several advantages over “untwisted” Wilson fermions, including simplified calculations of weak matrix elements. Sharpe and Wu used the effective chiral Lagrangian to analyze the phase diagram of two-flavor twisted mass lattice QCD as a function of the normal and twisted masses, generalizing previous work for the untwisted theory. Their calculations generated graphs of the condensate and pion masses for both scenarios, and they found a simple mathematical relation between them — a result that may be important to numerical simulations.
Numbers of Flavors in QED3
S. J. Hands, J. B. Kogut, L. Scorzatod, and C. G. Strouthos, “Non-compact QED3 with Nf = 1 and Nf = 4,” hep-lat/0404013 (2004). HEP, NSF, PPARC
If three-dimensional quantum electrodynamics (QED3) is a relevant
theory for the underdoped and non-superconducting region of the phase diagram
of high-Tc superconducting cuprate compounds, then the number
of fermion species Nf is an issue of concrete significance. Hands
et al. presented numerical results for non-compact QED3 for numbers
of flavors Nf = 1 and Nf = 4 and found that chiral
symmetry is spontaneously broken in the continuum limit for Nf
= 1, implying that the critical number of flavors Nfc is >1.
While some qualitative differences between Nf = 1 and Nf
= 4 emerged, it was difficult to determine whether Nf = 4 lies
above or below Nfc.