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- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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| 2. |
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| 3. |
- Dreber Almenberg, Anna, et al.
(författare)
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Gambling for global goods
- 2008
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Ingår i: Proceedings of the National Academy of Sciences. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 105, s. 2261-2262
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The human species has the sad capacity to destroy the climate of this planet. Many of our current behaviors and policies are almost ideally geared to meet this “goal” as quickly as possible. The per capita CO2emission of the United States is approximately twice that of the United Kingdom or Japan and three times that of France or Sweden. Why is this the case? Preserving the global climate is the biggest public goods game ever. It is a game that concerns all of us, and we cannot afford to lose it. Once the global climate is destroyed, not even enormous stock market gains could make us happy anymore. In a simple and elegant experiment, Milinski, Marotzke, and colleagues (1) have examined the ability of people to solve what they call a “collective risk social dilemma.” To play Milinski's game, you need six players and some money. Initially, all players receive 40 euros in their private accounts. The game has 10 rounds. In each round, players can transfer 0, 2, or 4 euros into a “climate account.” At the end of the game, the climate account must contain at least 120 euros. In this case, the climate has been saved and each player receives whatever is left in his private account. If the climate account does not reach its target, then the climate is lost with a 90% chance. In this case, all players loose all of their money.
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| 4. |
- Dreber Almenberg, Anna, et al.
(författare)
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Weighing Reward and Punishment - Response
- 2009
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Ingår i: Science. - : American Association for the Advancement of Science. - 0036-8075 .- 1095-9203. ; 326:5960, s. 1632-1633
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Dreber Almenberg, Anna, et al.
(författare)
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Winners don't punish
- 2008
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Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 452:7185, s. 348-351
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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