| 1. |
- Akhmedov, Evgeny, et al.
(författare)
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T violation in neutrino oscillations in matter
- 2001
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Ingår i: Nuclear Physics B. - : Elsevier Science B.V.. - 0550-3213 .- 1873-1562. ; 608:02-jan, s. 394-422
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Tidskriftsartikel (refereegranskat)abstract
- We consider the interplay of fundamental and matter-induced T violation effects in neutrino oscillations in matter. After discussing the general features of these effects we derive a simple approximate analytic expression for the T-violating probability asymmetry DeltaP(ab)(T) for three-flavour neutrino oscillations in a matter with an arbitrary density profile in terms of the two-flavour neutrino amplitudes. Explicit examples are given for the cases of a two-layer medium and for the adiabatic Emit in the general case. We then discuss implications of the obtained results for long baseline experiments. We show, in particular, that asymmetric matter effects cannot hinder the determination of the fundamental CP- and T-violating phase delta (CP) in the long baseline experiments as far as the error in this determination is larger than 1% at 99% CL. Since there are no T-violating effects in the two-flavour case, and in the limits of vanishing theta (13) or Deltam(21)(2) the three-flavour neutrino oscillations effectively reduce to the two-flavour ones, studying the T-violating asymmetries ApT ab can in principle provide us with a complementary means of measuring theta (13) and Deltam(21)(2).
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| 2. |
- Ambjørn, J., et al.
(författare)
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Stochastic confinement and dimensional reduction. (I). Four-dimensional SU(2) lattice gauge theory
- 1984
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Ingår i: Nuclear Physics, Section B. - : Elsevier BV. - 0550-3213. ; 240:2, s. 189-212
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Tidskriftsartikel (refereegranskat)abstract
- By Monte Carlo calculations on a 124 lattice we investigate four-dimensional SU(2) lattice gauge theory with respect to the conjecture that at large distances this theory reduces approximately to two-dimensional SU(2) lattice gauge theory. We find good numerical evidence for this conjecture. As a by-product we also measure the SU(2) string tension and find reasonable agreement with scaling. The "adjoint string tension" is also found to have a reasonable scaling behaviour.
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| 3. |
- Ambjørn, J., et al.
(författare)
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Stochastic confinement and dimensional reduction (II). Three-dimensional SU(2) lattice gauge theory
- 1984
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Ingår i: Nuclear Physics, Section B. - : Elsevier BV. - 0550-3213. ; 240:4, s. 533-542
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Tidskriftsartikel (refereegranskat)abstract
- We study 3-dimensional SU(2) lattice gauge theory with respect to dimensional reduction. By Monte Carlo calculations we find that this reduction is valid to a good approximation (within ≈10%). The adjoint string tension is found to scale approximately. We also compare the adjoint string tension with a string theory.
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| 4. |
- Ambjørn, J., et al.
(författare)
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The complex langevin equation and Monte Carlo simulations of actions with static charges
- 1986
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Ingår i: Nuclear Physics, Section B. - 0550-3213. ; 275:3, s. 375-397
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Tidskriftsartikel (refereegranskat)abstract
- We explore the possibilities of using the complex Langevin equation to Monte Carlo generate configurations of gauge theories with static charges present in the action. Successful results are obtained for systems that possess nontrivial saddle-point (classical) solutions. For that reason the algorithm works impressively for two-dimensional U(1) in the entire β-range whereas for three- and four-dimensional U(1) the applicability is limited to the weak coupling regime (large β). The method fails completely for SU(2) and SU(3).
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| 5. |
- Ambjørn, J., et al.
(författare)
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Three-dimensional lattice gauge theory and strings
- 1984
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Ingår i: Nuclear Physics, Section B. - : Elsevier BV. - 0550-3213. ; 244:1, s. 262-276
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Tidskriftsartikel (refereegranskat)abstract
- We consider SU(2) lattice gauge theory in three dimensions. The Wilson loops are found to be well described by a simple string model in the approximate scaling region.
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| 6. |
- 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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| 7. |
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| 8. |
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| 9. |
- Andersson, B., et al.
(författare)
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A statistical model for quark fragmentation into mesons with emphasis on vector meson contributions
- 1978
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Ingår i: Nuclear Physics, Section B. - : Elsevier BV. - 0550-3213. ; 135:2, s. 273-284
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Tidskriftsartikel (refereegranskat)abstract
- This paper is the first part of a program to deal with the relative importance of the different effects in a colour dipole field when the field energy is transformed into hadrons according to a statistical scheme with the sole constraints coming from energy and momentum conservation and the requirements of scaling. In this paper we treat the meson distributions from quark fragmentation with particular emphasis on the importance of a vector meson production of the size observed at present. We neglect diquark formation and the baryon distributions as a first approximation. The simplicity of the approach will make it possible to easily understand the size and the shape of the different contributions.
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| 10. |
- Andersson, Bo, et al.
(författare)
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Bose-Einstein correlations in the Lund model
- 1998
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Ingår i: Nuclear Physics B. - 0550-3213. ; 513:3, s. 627-644
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Tidskriftsartikel (refereegranskat)abstract
- By providing the Lund Model fragmentation process with a quantum-mechanical framework we extend the results of previous work to situations where there are very many identical bosons. We investigate the features of the weight distributions in some detail and in particular exhibit three-particle BE-correlations, the influence on the rho-spectrum and the difference between charged and neutral pion correlations.
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