| 1. |
- Abele, H., et al.
(författare)
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Particle physics at the European Spallation Source
- 2023
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Ingår i: Physics reports. - : Elsevier. - 0370-1573 .- 1873-6270. ; 1023, s. 1-84
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Forskningsöversikt (refereegranskat)abstract
- Presently under construction in Lund, Sweden, the European Spallation Source (ESS) will be the world’s brightest neutron source. As such, it has the potential for a particle physics program with a unique reach and which is complementary to that available at other facilities. This paper describes proposed particle physics activities for the ESS. These encompass the exploitation of both the neutrons and neutrinos produced at the ESS for high precision (sensitivity) measurements (searches).
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| 2. |
- Aoyama, T., et al.
(författare)
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The anomalous magnetic moment of the muon in the Standard Model
- 2020
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Ingår i: Physics reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 887, s. 1-166
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Forskningsöversikt (refereegranskat)abstract
- We review the present status of the Standard Model calculation of the anomalous magnetic moment of the muon. This is performed in a perturbative expansion in the fine-structure constant α and is broken down into pure QED, electroweak, and hadronic contributions. The pure QED contribution is by far the largest and has been evaluated up to and including O(α5) with negligible numerical uncertainty. The electroweak contribution is suppressed by (mμ/MW)2 and only shows up at the level of the seventh significant digit. It has been evaluated up to two loops and is known to better than one percent. Hadronic contributions are the most difficult to calculate and are responsible for almost all of the theoretical uncertainty. The leading hadronic contribution appears at O(α2) and is due to hadronic vacuum polarization, whereas at O(α3) the hadronic light-by-light scattering contribution appears. Given the low characteristic scale of this observable, these contributions have to be calculated with nonperturbative methods, in particular, dispersion relations and the lattice approach to QCD. The largest part of this review is dedicated to a detailed account of recent efforts to improve the calculation of these two contributions with either a data-driven, dispersive approach, or a first-principle, lattice-QCD approach. The final result reads aμSM = 116 591 810(43) x 10-11 and is smaller than the Brookhaven measurement by 3.7 σ. The experimental uncertainty will soon be reduced by up to a factor four by the new experiment currently running at Fermilab, and also by the future J-PARC experiment. This and the prospects to further reduce the theoretical uncertainty in the near future - which are also discussed here - make this quantity one of the most promising places to look for evidence of new physics.
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| 3. |
- Anzivino, G., et al.
(författare)
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Workshop summary: Kaons@CERN 2023
- 2024
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Ingår i: European Physical Journal C. - 1434-6044. ; 84:4
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Tidskriftsartikel (refereegranskat)abstract
- Kaon physics is at a turning point – while the rare-kaon experiments NA62 and KOTO are in full swing, the end of their lifetime is approaching and the future experimental landscape needs to be defined. With HIKE, KOTO-II and LHCb-Phase-II on the table and under scrutiny, it is a very good moment in time to take stock and contemplate about the opportunities these experiments and theoretical developments provide for particle physics in the coming decade and beyond. This paper provides a compact summary of talks and discussions from the Kaons@CERN 2023 workshop, held in September 2023 at CERN. © The Author(s) 2024.
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| 4. |
- Bijnens, J., et al.
(författare)
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Pion-pion scattering at low energy
- 1997
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Ingår i: Nuclear Physics B. - 0550-3213. ; 508:1-2, s. 263-310
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Tidskriftsartikel (refereegranskat)abstract
- We present technical details of the evaluation of the elastic ππ scattering amplitude to two loops in chiral perturbation theory. In particular, we elaborate on the renormalization procedure at the two-loop order and on the evaluation of the relevant Feynman diagrams that can all be expressed in terms of elementary functions. For the sake of clarity, we discuss these matters both in the N-component φ4 theory (in its symmetric phase) and in chiral perturbation theory. Estimates for the relevant low-energy constants of O(p6) are presented. Threshold parameters and phase shifts are then calculated for two sets of O(p4) coupling constants and compared with experiment. We comment on the extraction of threshold parameters from phase shift data.
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| 5. |
- Amoros, G., et al.
(författare)
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QCD isospin breaking in meson masses, decay constants and quark mass ratios
- 2001
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Ingår i: Nuclear Physics B. - 0550-3213. ; 602:1-2, s. 87-108
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Tidskriftsartikel (refereegranskat)abstract
- The procedure to calculate masses and matrix-elements in the presence of mixing of the basis states is explained in detail. We then apply this procedure to the two-loop calculation in Chiral Perturbation Theory of pseudoscalar masses and decay constants including quark mass isospin breaking. These results are used to update our analysis of Kℓ4 done previously and obtain a value of mu/md in addition to values for the low-energy-constants Li r.
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| 6. |
- Bijnens, J., et al.
(författare)
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Chiral corrections to vector meson decay constants
- 1998
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 429:1-2, s. 111-120
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Tidskriftsartikel (refereegranskat)abstract
- We calculate the leading quark mass corrections of order mqlog(mq), mq and m3/2 q to the vector meson decay constants within heavy vector meson chiral perturbation theory. We discuss the issue of electromagnetic gauge invariance and the heavy mass expansion. Reasonably good fits to the observed decay constants are obtained.
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| 7. |
- Bijnens, Johan, et al.
(författare)
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Comment on the pion pole part of the light-by-light contribution to the muon g-2
- 2002
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Ingår i: Nuclear Physics, Section B. - 0550-3213. ; 626:1-2, s. 410-411
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Tidskriftsartikel (refereegranskat)abstract
- We comment on the recent calculations of the pion pole part of the light-by-light contribution to the muon anomalous magnetic moment and we point out where the analysis in our previous work was mistaken.
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| 8. |
- Bijnens, J., et al.
(författare)
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Double chiral logs
- 1998
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 441:1-4, s. 437-446
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Tidskriftsartikel (refereegranskat)abstract
- We determine the full structure of the leading (double-pole) divergences of O(p6) in the meson sector of chiral perturbation theory. The field theoretic basis for this calculation is described. We then use an extension of this result to determine the p6 contributions containing double chiral logarithms (L2), single logarithms times p4 constants (L × Lr i) and products of two p4 constants (Lr i × Lr j) for Fπ, FK/Fπ, Kl3 and Ke4 form factors. Numerical results are presented for these quantities.
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| 9. |
- Bijnens, Johan, et al.
(författare)
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Eta decays at and beyond p(4) in Chiral Perturbation Theory
- 2002
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Ingår i: PHYSICA SCRIPTA. - 0031-8949 .- 1402-4896. ; 99, s. 34-44
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Konferensbidrag (refereegranskat)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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| 10. |
- Bijnens, Johan, et al.
(författare)
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Hadronic matrix elements for kaons
- 2004
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Ingår i: Nuclear Physics B - Proceedings Supplements. - : Elsevier BV. - 0920-5632. ; 133, s. 245-251
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Tidskriftsartikel (refereegranskat)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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| 11. |
- Bijnens, Johan, et al.
(författare)
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QCD Short-distance constraints and hadronic approximations
- 2003
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Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; :4: 055
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Tidskriftsartikel (refereegranskat)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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| 12. |
- Bijnens, J., et al.
(författare)
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QCD signatures of narrow graviton resonances in hadron colliders
- 2001
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 503:3-4, s. 341-348
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Tidskriftsartikel (refereegranskat)abstract
- We show that the characteristic p⊥ spectrum yields valuable information for the test of models for the production of narrow graviton resonances in the TeV range at LHC. Furthermore, it is demonstrated that in those scenarios the parton showering formalism agrees with the prediction of NLO matrix element calculations.
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| 13. |
- Bijnens, Johan, et al.
(författare)
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The B-K kaon parameter in the chiral limit
- 2006
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Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; :3
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Tidskriftsartikel (refereegranskat)abstract
- We introduce four-point functions in the hadronic ladder resummation approach to large N-c QCD Green functions. We determine the relevant one to calculate the B-K kaon parameter in the chiral limit. This four-point function contains both the large momenta QCD OPE and the small momenta ChPT at NLO limits, analytically. We get (B) over cap (X)(K) = 0.38 +/- 0.15. We also give the ChPT result at NLO for the relevant four-point function to calculate B-K outside the chiral limit, while the leading QCD OPE is the same as the chiral limit one.
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| 14. |
- Bijnens, Johan, et al.
(författare)
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The BK kaon parameter in the 1/Nc expansion
- 2005
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Ingår i: [Host publication title missing]. ; , s. 179-190
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Konferensbidrag (refereegranskat)abstract
- We present work going on calculating the kaon BK parameter in the 1/Nc expansion. The goal of this work is to analyze analytically in the presence of chiral corrections this phenomenologically very important parameter. We present the method used and preliminary results for the chiral limit value for which we get the invariant BKchi=0.29 +- 0.15. We also give some analytical indications of why the large N_c prediction of BK= 3/4 may have small 1/Nc corrections in the real case.
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| 15. |
- Bijnens, J., et al.
(författare)
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Vector meson masses in chiral perturbation theory
- 1997
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Ingår i: Nuclear Physics B. - 0550-3213. ; 501:2, s. 495-517
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Tidskriftsartikel (refereegranskat)abstract
- We discuss the vector meson masses within the context of chiral perturbation theory performing an expansion in terms of the momenta, quark masses and 1/Nc. We extend the previous analysis to include isospin breaking effects and also include up to order p4. We discuss vector meson chiral perturbation theory in some detail and present a derivation from a relativistic Lagrangian. The unknown coefficients are estimated in various ways. We also discuss the relevance of electromagnetic corrections and the implications of the present calculation for the determination of quark masses.
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| 16. |
- Gamiz, E, et al.
(författare)
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Matching the electroweak penguins Q(7) and Q(8)
- 2003
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Ingår i: 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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Konferensbidrag (refereegranskat)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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