Matrix elements of four-fermion operators with quenched Wilson fermions

Gupta, Rajan; Bhattacharya, Tanmoy; Sharpe, Stephen R.

doi:10.1103/physrevd.55.4036

Cited by 120 publications

(176 citation statements)

References 26 publications

(77 reference statements)

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“…This is in agreement with (20) and (21), but not with all sum rule results representated by the range in (19). …”

Section: Phenomenologysupporting

confidence: 81%

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Theoretical status of

Nierste

2000

Nuclear Physics B - Proceedings Supplements

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I give a detailed introduction into the theoretical formalism for ǫ ′ /ǫ, which measures direct CP-violation in K → ππ decays. The current status of hadronic matrix elements and the strange quark mass is discussed. Several possible explanations of the unexpectedly high experimental results for ǫ ′ /ǫ are pointed out: A small strange quark mass, an enhancement of the hadronic parameter B (1/2) 6 from the σ resonance, an underestimate of isospin breaking and possible new physics contributions in the sdZ-vertex and the sd-gluon-vertex. Setting the sceneThe establishment of direct CP-violation rules out old superweak models. Yet while the Standard Model predicts a non-vanishing ǫ ′ /ǫ, the value in (1) came as a surprise to many theorists, as it exceeds most theoretical predictions. In the following I will try to illuminate the possible sources of this discrepancy. The flavour eigenstates of neutral K mesons, Fig. 1. CP-violation in neutral Kaon decay is illustrated in Fig. 3.

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“…This is in agreement with (20) and (21), but not with all sum rule results representated by the range in (19). …”

Section: Phenomenologysupporting

confidence: 81%

“…Finally not all systematic errors associated with the discretization of QCD are fully understood yet. Recent lattice results for B (3/2) in the MS NDR scheme are [18] 0.81(3)(3) [19] 0.82 (2) [20] 1.03 (3) (non-pert. matching) [20].…”

Section: Hadronic Matrix Elementsmentioning

confidence: 99%

Theoretical status of

Nierste

2000

Nuclear Physics B - Proceedings Supplements

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“…For unimproved Wilson fermions one finds, after tadpole improvement (picking for definiteness the tadpole improvement scheme of Ref. [25]), c i = −0.1, −9.7, −7.8, −2.9, −4.3 for i = S, P, V, A, T , using the same renormalization scheme and scale for the continuum operator as in the tables. We have not been able to find the corresponding results for improved Wilson fermions incorporating tadpole improvement, but it is clear from Table 3 of Ref.…”

Section: Namementioning

confidence: 99%

One-loop matching coefficients for improved staggered bilinears

Lee

Sharpe

2002

Phys. Rev. D

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We calculate one-loop matching factors for bilinear operators composed of improved staggered fermions. We compare the results for different improvement schemes used in the recent literature, all of which involve the use of smeared links. These schemes aim to reduce, though not completely eliminate, O(a 2 ) discretization errors. We find that all these improvement schemes substantially reduce the size of matching factors compared to unimproved staggered fermions. The resulting corrections are comparable to, or smaller than, those found with Wilson and domain-wall fermions. In the best case ("Fat-7" and mean-field improved HYP links) the corrections are 10% or smaller at 1/a = 2 GeV.

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“…PT stands for perturbative matching, NP for nonperturbative matchingà la [15] and WI, for matching using Ward identities. The references for the different results are: CP-PACS [3], RBC [4], BS [40] (with NPR, hep-lat/9909108), JLQCD (KS) [42], KGS [43], OSU and N f = 3 [44], KSGP [45], JLQCD (Wil) [46], UKQCD [47], APE [5], BGS [48].…”

Section: Chiral Perturbation Theory Resultsmentioning

confidence: 99%