# BK-parameter from Nf = 2 twisted mass lattice QCD

Abstract : We present an unquenched $N_f=2$ lattice computation of the $B_{K}$ parameter which controls $K^0-\bar K^0$ oscillations. A partially quenched setup is employed with two maximally twisted dynamical (sea) light Wilson quarks, and valence quarks of both the maximally twisted and the Osterwalder--Seiler variety. Suitable combinations of these two kinds of valence quarks lead to a lattice definition of the $B_{K}$ parameter which is both multiplicatively renormalizable and O($a$) improved. Employing the non-perturbative RI-MOM scheme, in the continuum limit and at the physical value of the pion mass we get $B^{\rm RGI}_K=0.729\pm 0.030$, a number well in line with the existing quenched and unquenched determinations.
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Journal articles
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http://hal.in2p3.fr/in2p3-00524186
Contributor : Emmanuelle Vernay <>
Submitted on : Thursday, October 7, 2010 - 10:57:30 AM
Last modification on : Thursday, November 19, 2020 - 12:58:48 PM

### Citation

M. Constantinou, P. Dimopoulos, R. Frezzotti, K. Jansen, V. Gimenez, et al.. BK-parameter from Nf = 2 twisted mass lattice QCD. Physical Review D, American Physical Society, 2011, 83, pp.014505. ⟨10.1103/PhysRevD.83.014505⟩. ⟨in2p3-00524186⟩

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