| 1. |
- Bijnens, Johan
(author)
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Chiral dynamics in the meson sector at two loops
- 2003
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In: AIP Conference Proceedings. - : AIP. - 0094-243X .- 1551-7616. ; 698, s. 407-410
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Conference paper (peer-reviewed)abstract
- I give a very short introduction to chiral perturbation theory and an overview of the next-to-next-to-leading order three-flavour calculations done. I discuss those relevant for an improvement in the accuracy of the measurement of Vus in more detail. One major conclusion is that all needed p6 low energy constants can be obtained from experiment via the scalar form-factor in Kl3 decays
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| 2. |
- Bijnens, Johan
(author)
-
Chiral Lagrangians
- 2002
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In: INTERNATIONAL JOURNAL OF MODERN PHYSICS A. - 0217-751X. ; 17:23, s. 3154-3169
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Conference paper (peer-reviewed)abstract
- An overview of the field of Chiral Lagrangians is given. This includes Chiral Perturbation Theory and resummations to extend, it to higher energies, applications to the muon anomalous magnetic moment, epsilon(1)/epsilon and others.
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| 3. |
- Bijnens, Johan, et al.
(author)
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Chiral limit prediction for ε′/K/εK at NLO in 1/Nc
- 2001
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In: Nuclear Physics B - Proceedings Supplements. - 0920-5632. ; 96:1-3, s. 354-363
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Journal article (peer-reviewed)abstract
- We report on a calculation of ε′K/εK at next-to-leading in the 1/Nc expansion and to lowest order in Chiral Perturbation Theory. We discuss the short-distance matching, the scale and scheme dependence as well as the long-distance short-distance matching. We include the two known chiral corrections to our result and discuss further order p4 corrections to it.
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| 4. |
- Bijnens, Johan, et al.
(author)
-
Chiral perturbation theory at two loops and the measurement of V(us)
- 2003
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In: XXXVIII Rencontres de Moriond. ; , s. 313-316
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Conference paper (peer-reviewed)abstract
- I give an overview of the calculations done in three-flavour Chiral perturbation theory at next-to-next-to-leading order with an emphasis on those relevant for an improvement in the accuracy of the measurement of Vus. It is pointed out that all needed low energy constants can be obtained from experiment via the scalar form-factor in Kl3 decays
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| 5. |
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| 6. |
- Bijnens, Johan, et al.
(author)
-
Eta decays at and beyond p(4) in Chiral Perturbation Theory
- 2002
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In: PHYSICA SCRIPTA. - 0031-8949 .- 1402-4896. ; 99, s. 34-44
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Conference paper (peer-reviewed)abstract
- An overview is given of Chiral Perturbation Theory and various applications to eta decays. In particular. the main decay eta --> 3pi is discussed at the one-loop level, and estimates of the higher order corrections are given. The importance of p(6) and higher order effects in double Dalitz and eta --> pi(0)gammagamma decays is pointed out. In all these cases the need for new experimental results is stressed.
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| 7. |
- Bijnens, Johan, et al.
(author)
-
Exploring light-cone sum rules for pion and kaon form factors
- 2002
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In: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 26:1, s. 67-79
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Journal article (peer-reviewed)abstract
- We analyze the higher-twist effects and the SU(3)-flavor symmetry breaking in the correlation functions used to calculate form factors of pseudoscalar mesons in the QCD light-cone sum rule approach. It is shown that the Ward identities for these correlation functions yield relations between twist-4 two-and three-particle distribution amplitudes. In addition to the relations already obtained from the QCD equations of motions, we have found a new one. With the help of these relations, the twist-4 contribution to the light-cone sum rule for the. pion electromagnetic form factor: is reduced to a very simple form. Simultaneously, we correct a sign error in an earlier calculation. The updated light-cone sum rule prediction for the pion form factor at intermediate momentum transfers is compared with the recent Jefferson Lab data. Furthermore, from the correlation functions with strange-quark currents the kaon electromagnetic form factor and the K --> pi weak transition form factors are predicted with O(m(s)) similar to O(m(K)(2)) accuracy.
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| 8. |
- Bijnens, Johan, et al.
(author)
-
Hadronic matrix elements for kaons
- 2004
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In: Nuclear Physics B - Proceedings Supplements. - : Elsevier BV. - 0920-5632. ; 133, s. 245-251
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Journal article (peer-reviewed)abstract
- We review some work done by us calculating matrix elements for Kaons. Emphasis is put on the matrix elements which are relevant to predict non-leptonic Kaon CP violating observables. In particular, we recall our results for the (B) over cap (K) parameter which governs the (K-0) over bar - K-0 mixing and update our results for epsilon(K)' including estimated all-higher-order CHPT corrections and the new results from recent analytical calculations of the DeltaI = 3/2 component. Some comments on future prospects on calculating matrix elements for Kaons are also added.
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| 9. |
- Bijnens, Johan, et al.
(author)
-
Isospin breaking in K -> 3 pi decays I: strong isospin breaking
- 2004
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In: Nuclear Physics, Section B. - : Elsevier BV. - 0550-3213. ; 697:1-2, s. 319-342
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Journal article (peer-reviewed)abstract
- The CP conserving amplitudes for the decays K --> 3pi are calculated in Chiral Perturbation Theory. The calculation is made at the next-to-leading order including strong and local electromagnetic isospin breaking. A comparison is made between the squared amplitudes with and without isospin violation to estimate the size of the effect. We find corrections of order five percent in the amplitudes.
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| 10. |
- Bijnens, Johan, et al.
(author)
-
K -> 3 pi decays in chiral perturbation theory
- 2003
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In: Nuclear Physics, Section B. - 0550-3213. ; 648:1-2, s. 317-344
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Journal article (peer-reviewed)abstract
- The CP conserving amplitudes for the decays K --> 3pi are calculated in chiral perturbation theory at the next-to-leading order. We present the expressions in a compact form with single parameter functions only. These expressions are then fitted to all available K --> 2pi and K --> 3pi data to obtain a fit of the parameters that occur. We compare with the work of Kambor, Missimer and Wyler. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 11. |
- Bijnens, Johan, et al.
(author)
-
K-l3 decays in chiral perturbation theory
- 2003
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In: Nuclear Physics, Section B. - 0550-3213. ; 669:1-2, s. 341-362
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Journal article (peer-reviewed)abstract
- The process K-l3 is calculated to two-loop order (p(6)) in chiral perturbation theory (ChPT) in the isospin conserved case. We present expressions suitable for use with previous work in two-loop ChPT where the order p(4) parameters (L-i(r)) were determined from experiment. We point out that all the order p(6) parameters (C-i(r)) that appear in the value of f(+)(0) relevant for the determination of V-us can be determined from K-l3 measurements via the slope and the curvature of the scalar form-factor. As by product we update the value of the CKM matrix element V-us. (C) 2003 Elsevier B.V. All rights reserved.
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| 12. |
- Bijnens, Johan, et al.
(author)
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Large extra dimensions in rare decays
- 2000
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; 2000:JHEP10(2000)
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Journal article (peer-reviewed)abstract
- The prospect of experimental verification of the large extra dimension scenario in rare decays is discussed. The case of J/ψ and γ to photon + missing energy is calculated in detail, and it is shown that the limit on the compactification scale MS lies at present in the ten GeV range. In contrast to the quarkonium systems, signals in Kaon and Pion decays will be small.
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| 13. |
- Bijnens, Johan, et al.
(author)
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Matching the electroweak penguins q7, q8 and spectral correlators
- 2001
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; 2001:JHEP10(2001)
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Journal article (peer-reviewed)abstract
- Exact analytical expressions for the ∆S = 1 coupling Im GE in terms of observable spectral functions are given. This coupling determines the size of the ∆I = 3/2 contribution to ε′ . We show analytically how the scheme-dependence and scale dependences vanish to all orders in 1/Nc and NLO in αS explicitly both for Q7 and Q8 . Numerical results are derived for both Q7 and Q8 from the τ-data and known results on the scalar spectral functions. In particular we study the effect of all higher dimension operators. The coefficients of the leading operators in the OPE of the needed correlators are derived to NLO in αS .
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| 14. |
- Bijnens, Johan
(author)
-
Penguins 2002: penguins in K→ππ decays
- 2002
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In: Proceedings of the Conference on Continuous Advances in QCD 2002. ARKADYFEST Honoring the 60th Birthday of Arkady Vainshtein. - 9812382151 ; , s. 3-22
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Conference paper (peer-reviewed)abstract
- This talk contains a short overview of the history of the interplay of the weak and the strong interaction and CP-violation. It describes the phenomenology and the basic physics mechanisms involved in the standard model calculations of K→ππ decays with an emphasis on the evaluation of penguin operator matrix-elements
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| 15. |
- Bijnens, Johan, et al.
(author)
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pi K scattering in three flavour ChPT : π K scattering in three flavour ChPT
- 2004
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; 2004:JHEP05(2004), s. 811-833
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Journal article (peer-reviewed)abstract
- We present the scattering lengths for the piK processes in the three flavour Chiral Perturbation Theory (ChPT) framework at next-to-next-to-leading order (NNLO). The calculation has been performed analytically but we only include analytical results for the dependence on the low-energy constants (LECs) at NNLO due to the size of the expressions. These results, together with resonance estimates of the NNLO LECs are used to obtain constraints on the Zweig rule suppressed LECs at NLO, L-4(r) and L-6(r). Contrary to expectations from NLO order calculations we find them to be compatible with zero. We do a preliminary study of combining the results from pipi scattering, piK scattering and the scalar form-factors and find only a marginal compatibility with all experimental/dispersive input data.
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| 16. |
- Bijnens, Johan, et al.
(author)
-
Pi pi scattering in three flavor ChPT : ππ scattering in three flavour ChPT
- 2004
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; 05:JHEP01(2004)
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Journal article (peer-reviewed)abstract
- We present the scattering lengths for the pi-pi processes in the three flavour Chiral Perturbation Theory (ChPT) framework at next-to-next-to-leading order. We then combine this calculation with the determination of the parameters from $Ke4 and the masses and decay constants and compare with the results of a dispersive analysis of pi-pi scattering. The comparison indicates a small but nonzero value for the 1/Nc suppressed NLO low energy constants L4r and L6r.
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| 17. |
- Bijnens, Johan, et al.
(author)
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Pion and kaon electromagnetic form factors
- 2002
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; :3
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Journal article (peer-reviewed)abstract
- We study the electromagnetic form factor of the pion and kaons at low-energies with the use of Chiral Perturbation Theory. The analysis is performed within the three flavour framework and at next-to-next-to-leading order. We explain carefully all the relevant consistency checks on the expressions, present full analytical results for the pion form factor and describe all the assumptions in the analysis. From the phenomenological point of view we make use of our expression and the available data to obtain the charge radius of the pion obtaining [r(2)](V)(pi) = (0.452 +/- 0.013)fm(2), as well as the low-energy constant L-9(r) (m(rho)) = (5.93 +/- 0.43) x 10(3). We also obtain experimental values for 3 combinations of O(p(6)) constants.
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| 18. |
- Bijnens, Johan
(author)
-
Progress in K → ππ decays
- 2000
-
In: Nuclear Physics A. - 0375-9474. ; 663-664, s. 927-930
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Journal article (peer-reviewed)abstract
- Recent work by J. Prades and myself on K → ππ is described. The first part describes our method to connect in a systematic fashion the short-distance evolution with long-distance matrix-element calculations taking the scheme dependence of the short-distance evolution into account correctly. In the second part I show the results we obtain for the ΔI = 1/2 rule in the chiral limit.
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| 19. |
- Bijnens, Johan, et al.
(author)
-
Pseudoscalar meson mass to two loops in three-flavor partially quenched chiral perturbation theory
- 2004
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In: Physical Review D (Particles and Fields). - 0556-2821. ; 70:11
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Journal article (peer-reviewed)abstract
- This paper presents a first study of the pseudoscalar meson masses to two loops, or next-to-next-to-leading order, within the supersymmetric formulation of partially quenched chiral perturbation theory (PQchiPT). The expression for the pseudoscalar meson mass in the case of three valence and three sea quarks with equal masses, but different from each other, is given to O(p(6)), along with a numerical analysis.
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| 20. |
- Bijnens, Johan, et al.
(author)
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QCD and weak interactions of light quarks
- 2002
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In: at the frontier of Particle Physics: handbook of QCD. - 9812380280 ; 4, s. 2155-2214
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Book chapter (other academic/artistic)abstract
- This review contains an overview of strong interaction effects in weak decays starting with a historical introduction. It contains a short overview of semileptonic decays and their relevance for measuring CKM matrix elements. The main part is devoted to the theoretical calculation on nonleptonic matrix elements relevant for K0-K0bar mixing and K to pi pi decays. It concludes with a short summary of rare kaon decays.
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| 21. |
- Bijnens, Johan, et al.
(author)
-
QCD Short-distance constraints and hadronic approximations
- 2003
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; :4: 055
-
Journal article (peer-reviewed)abstract
- This paper discusses a general class of ladder resummation inspired hadronic approximations. It is found that this approach naturally reproduces many successes of single meson per channel saturation models (e.g. VMD) and NJL based models. In particular the existence of a constituent quark mass and a gap equation follows naturally. We construct an approximation that satisfies a large set of QCD short-distance and large N-c constraints and reproduces many hadronic observables. We show how there exists in general a problem between QCD short-distance constraints for Green Functions and those for form factors and cross-sections following from the quark-counting rule. This problem while expected for Green functions that do not vanish in purely perturbative QCD also persists for many Green functions that are order parameters.
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| 22. |
- Bijnens, Johan, et al.
(author)
-
Scalar form factors in SU(3) chiral perturbation theory
- 2003
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; 10:061
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Journal article (peer-reviewed)abstract
- The scalar form factors for the pions and kaons are calculated in SU(3) Chiral Perturbation Theory at order p(6), in the isospin limit m(u)=m(d)=(m) over cap. We find in general sizable corrections of O(p(6)). We use our results to obtain information on the 1/N-c suppressed low energy constants L-4(r) and L-6(r) as well as on two O(p(6)) low energy constants. We present some numerical results for masses and decay constants as well. We derive a relation for the scalar form factors analogous to Sirlin's relation for vector form factors.
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| 23. |
- Bijnens, Johan, et al.
(author)
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Scheme dependence of weak matrix elements in the 1/Nc expansion
- 2000
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; 2000:JHEP01(2000)
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Journal article (peer-reviewed)abstract
- We show how the scheme- and scale-dependence of the short-distance operator product expansion with four-quark operators can be correctly accounted for in the framework of the 1/Nc-expansion once the hadronization of two-quark currents has been fixed. We show formulas explicitly in the case of the BK-parameter. We then use them together with our earlier estimates of the long-distance effects. We compare Chiral Perturbation Theory at Leading- and Next-to-Leading-Order with the ENJL model results in the chiral limit. Good matching between the long-and short-distance regimes is obtained and our final value for the physical scheme independent B̂K is 0.77 ± 0.05 ± 0.05.
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| 24. |
- Bijnens, Johan, et al.
(author)
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The anomalous chiral Lagrangian of order p(6)
- 2002
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In: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 23:3, s. 539-544
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Journal article (peer-reviewed)abstract
- dWe construct the effective chiral Lagrangian for chiral perturbation theory in the mesonic odd-intrinsic-parity sector at order p(6). The Lagrangian contains 24 in principle measurable terms and no contact terms for the general case of N-f light flavors, 23 terms for three and 5 for two flavors. In the two flavor case we need a total of 13 terms if ail external singlet vector field is included. We discuss and implement the methods used to reduce to a minimal set. The infinite parts needed for renormalization are calculated and presented as well.
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| 25. |
- Bijnens, Johan, et al.
(author)
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ε′K/εK in the chiral limit
- 2000
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In: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; 2000:JHEP06(2000)
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Journal article (peer-reviewed)abstract
- The K → ππ system is analyzed in the chiral limit within the Standard Model. We discuss how to connect the short-distance running in the |ΔS| = 1 case to the matrix-elements calculated in a low-energy approximation in a scheme-independent fashion. We calculate this correction and the resulting Wilson Coefficients. The matrix elements are calculated to next-to-leading order in the 1/Nc expansion and combined with the Wilson coefficients to calculate the two isospin amplitudes and ε′K. The ΔI = 1/2 rule is reproduced within expected errors and we obtain a substantially larger value for ε′K/εK than most other analysises. We discuss the reasons for this difference. We also suggest that the X-boson method is an option for lattice QCD calculations.
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| 26. |
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Effective field theories in QCD
- 2002
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Editorial proceedings (peer-reviewed)abstract
- These are the proceedings of the workshop on ``Effective Field Theories of QCD'' held at the Physikzentrum Bad Honnef of the Deutsche Physikalische Gesellschaft, Bad Honnef, Germany from November 26 to 30, 2001. The workshop concentrated on Chiral Perturbation Theory in its various settings, its relations with lattice QCD and dispersion theory and the use of effective field theories in systems with one, two or more nucleons as well as at high baryon densities. Included are a short contribution per talk and a listing of some review papers on the subject.
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| 27. |
- Gamiz, E, et al.
(author)
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Matching the electroweak penguins Q(7) and Q(8)
- 2003
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In: Nuclear Physics B - Proceedings Supplements (Proceedings of the QCD 02 9th High-Energy Physics International Conference on Quantum ChromoDynamics). - 0920-5632. ; 121, s. 195-198
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Conference paper (peer-reviewed)abstract
- We report on recent advances on the computation of the matrix elements of the electroweak penguins Q(7) and Q(8) which are relevant for the DeltaI = 3/2 contribution to epsilon'(K) in the chiral limit. The matching of scale and scheme dependences between Wilson coefficients and these matrix elements is done analytically at NLO in alpha(S).
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| 28. |
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