| 1. |
- Allanach, Benjamin C., et al.
(författare)
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Simple and statistically sound strategies for analysing physical theories
- 2022
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Ingår i: Reports on progress in physics (Print). - : Institute of Physics Publishing (IOPP). - 0034-4885 .- 1361-6633. ; 85:5
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Forskningsöversikt (refereegranskat)abstract
- Physical theories that depend on many parameters or are tested against data from many different experiments pose unique challenges to statistical inference. Many models in particle physics, astrophysics and cosmology fall into one or both of these categories. These issues are often sidestepped with statistically unsound ad hoc methods, involving intersection of parameter intervals estimated by multiple experiments, and random or grid sampling of model parameters. Whilst these methods are easy to apply, they exhibit pathologies even in low-dimensional parameter spaces, and quickly become problematic to use and interpret in higher dimensions. In this article we give clear guidance for going beyond these procedures, suggesting where possible simple methods for performing statistically sound inference, and recommendations of readily-available software tools and standards that can assist in doing so. Our aim is to provide any physicists lacking comprehensive statistical training with recommendations for reaching correct scientific conclusions, with only a modest increase in analysis burden. Our examples can be reproduced with the code publicly available at Zenodo.
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| 2. |
- Allanach, B. C., et al.
(författare)
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Global fits of third family hypercharge models to neutral current B-anomalies and electroweak precision observables
- 2021
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Ingår i: European Physical Journal C. - : Springer Nature. - 1434-6044 .- 1434-6052. ; 81:8
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Tidskriftsartikel (refereegranskat)abstract
- While it is known that third family hypercharge models can explain the neutral current B-anomalies, it was hitherto unclear whether the Z - Z' mixing predicted by such models could simultaneously fit electroweak precision observables. Here, we perform global fits of several third family hypercharge models to a combination of electroweak data and those data pertinent to the neutral current B-anomalies. While the Standard Model is in tension with this combined data set with a p-value of.0007, simple versions of the models (fitting two additional parameters each) providemuch improved fits. The original Third Family Hypercharge Model, for example, has a p-value of.065, with root Delta chi(2) = 6.5 sigma.
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| 3. |
- Bloor, Sanjay, et al.
(författare)
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The GAMBIT Universal Model Machine : from Lagrangians to likelihoods
- 2021
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Ingår i: European Physical Journal C. - : Springer Nature. - 1434-6044 .- 1434-6052. ; 81:12
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Tidskriftsartikel (refereegranskat)abstract
- We introduce the GAMBIT Universal Model Machine (GUM), a tool for automatically generating code for the global fitting software framework GAMBIT, based on Lagrangian-level inputs. GUM accepts models written symbolically in FeynRules and SARAH formats, and can use either tool along with MadG rap h and CaIcHEP to generate GAMBIT model, collider, dark matter, decay and spectrum code, as well as GAMBIT interfaces to corresponding versions of SPheno, micrOMEGAs, Pythia and Vevacious (C++). In this paper we describe the features, methods, usage, pathways, assumptions and current limitations of GUM. We also give a fully worked example, consisting of the addition of a Majorana fermion simplified dark matter model with a scalar mediator to GAMBIT via GUM, and carry out a corresponding fit.
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| 4. |
- Camargo-Molina, J. Eliel, et al.
(författare)
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Phase transitions in de Sitter spacetimes : Quantum Corrections
- 2023
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Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 107:6
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the decay rate of a false vacuum state in de Sitter space at high Hubble rates, using two methods: the Hawking-Moss instanton method which is fully quantum mechanical but relies on the saddlepoint approximation, and the Starobinsky-Yokoyama stochastic approach which is nonperturbative but does not include quantum effects. We use the flux over population method to compute the Hawking-Moss decay rate at one-loop order, and demonstrate that in its domain of validity, it is reproduced by the stochastic calculation using the one-loop constraint effective potential. This suggests that the stochastic approach together with the constraint effective potential can be used to accurately describe vacuum decay beyond the saddle-point approximation.
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| 5. |
- Camargo-Molina, J. Eliel, et al.
(författare)
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Phase transitions in de Sitter spacetimes : The stochastic formalism
- 2023
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Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 107:10
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Tidskriftsartikel (refereegranskat)abstract
- The stochastic spectral expansion method offers a simple framework for calculations in de Sitter spacetimes. We show how to extend its reach to metastable vacuum states, both in the case when the potential is bounded from below, and when it is unbounded from below and therefore no stable vacuum state exists. In both cases, the decay rate of the metastable vacuum is given by the lowest nonzero eigenvalue associated to the Fokker-Planck equation. We show how the corresponding eigenfunction determines the field probability distribution which can be used to compute correlation functions and other observables in the metastable vacuum state.
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