| 1. |
- Athron, Peter, et al.
(författare)
-
Global analyses of Higgs portal singlet dark matter models using GAMBIT
- 2019
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 79:1
-
Tidskriftsartikel (refereegranskat)abstract
- We present global analyses of effective Higgs portal dark matter models in the frequentist and Bayesian statistical frameworks. Complementing earlier studies of the scalar Higgs portal, we use GAMBIT to determine the preferred mass and coupling ranges for models with vector, Majorana and Dirac fermion dark matter. We also assess the relative plausibility of all four models using Bayesian model comparison. Our analysis includes up-to-date likelihood functions for the dark matter relic density, invisible Higgs decays, and direct and indirect searches for weakly-interacting dark matter including the latest XENON1T data. We also account for important uncertainties arising from the local density and velocity distribution of dark matter, nuclear matrix elements relevant to direct detection, and Standard Model masses and couplings. In all Higgs portal models, we find parameter regions that can explain all of dark matter and give a good fit to all data. The case of vector dark matter requires the most tuning and is therefore slightly disfavoured from a Bayesian point of view. In the case of fermionic dark matter, we find a strong preference for including a CP-violating phase that allows suppression of constraints from direct detection experiments, with odds in favour of CP violation of the order of 100:1. Finally, we present DDCalc2.0.0, a tool for calculating direct detection observables and likelihoods for arbitrary non-relativistic effective operators.
|
|
| 2. |
- Bechtle, Philip, et al.
(författare)
-
Killing the cMSSM softly
- 2016
-
Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 76:2, s. 1-22
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the constrained Minimal Supersymmetric Standard Model (cMSSM) in the light of constraining experimental and observational data from precision measurements, astrophysics, direct supersymmetry searches at the LHC and measurements of the properties of the Higgs boson, by means of a global fit using the program Fittino. As in previous studies, we find rather poor agreement of the best fit point with the global data. We also investigate the stability of the electro-weak vacuum in the preferred region of parameter space around the best fit point. We find that the vacuum is metastable, with a lifetime significantly longer than the age of the Universe. For the first time in a global fit of supersymmetry, we employ a consistent methodology to evaluate the goodness-of-fit of the cMSSM in a frequentist approach by deriving p values from large sets of toy experiments. We analyse analytically and quantitatively the impact of the choice of the observable set on the p value, and in particular its dilution when confronting the model with a large number of barely constraining measurements. Finally, for the preferred sets of observables, we obtain p values for the cMSSM below 10 %, i.e. we exclude the cMSSM as a model at the 90 % confidence level.
|
|
| 3. |
- Bloor, Sanjay, et al.
(författare)
-
The GAMBIT Universal Model Machine : from Lagrangians to likelihoods
- 2021
-
Ingår i: European Physical Journal C. - : Springer Nature. - 1434-6044 .- 1434-6052. ; 81:12
-
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.
|
|
| 4. |
- Camargo-Molina, José Eliel, et al.
(författare)
-
A new perspective on the electroweak phase transition in the Standard Model Effective Field Theory
- 2021
-
Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2021
-
Tidskriftsartikel (refereegranskat)abstract
- A first-order Electroweak Phase Transition (EWPT) could explain the observed baryon-antibaryon asymmetry and have a detectable gravitational wave signature, but this is not possible in the Standard Model. We therefore study the EWPT in the Standard Model Effective Field Theory (SMEFT) including dimension-six operators. A first-order EWPT has previously been shown to be possible in the SMEFT in scenarios with a tree-level barrier between minima, which requires a negative Higgs quartic coupling and a new physics scale low enough to raise questions about the validity of the EFT approach. In this work we show that a first-order EWPT is possible in a novel scenario where the barrier between minima is generated radiatively, the quartic coupling is positive, the scale of new physics is higher, and there is good agreement with experimental bounds. Our calculation is done in a consistent, gauge-invariant way, and we carefully analyze the scaling of parameters necessary to generate a barrier in the potential. We perform a global fit in the relevant parameter space and explicitly find the points with a first-order transition that agree with experimental data. We also briefly discuss the prospects for probing the allowed parameter space using di-Higgs production in colliders.
|
|
| 5. |
- Camargo-Molina, José Eliel, et al.
(författare)
-
All one-loop scalar vertices in the effective potential approach
- 2016
-
Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2016:8
-
Tidskriftsartikel (refereegranskat)abstract
- Using the one-loop Coleman-Weinberg effective potential, we derive a general analytic expression for all the derivatives of the effective potential with respect to any number of classical scalar fields. The result is valid for a renormalisable theory in four dimensions with any number of scalars, fermions or gauge bosons. This result corresponds to the zero-external momentum contribution to a general one-loop diagram with N scalar external legs. We illustrate the use of the general result in two simple scalar singlet extensions of the Standard Model, to obtain the dominant contributions to the triple couplings of light scalar particles under the zero external momentum approximation.
|
|
| 6. |
- Camargo-Molina, José Eliel, et al.
(författare)
-
Charged scalars from SU(3)3 theories
- 2016
-
Ingår i: Proceedings of Science. - Trieste, Italy : Sissa Medialab. - 1824-8039. ; 286
-
Konferensbidrag (refereegranskat)abstract
- Inspired by a recently proposed GUT model based on the trinification (SU(3)3) gauge group with a global family (SU(3)F) symmetry, we consider an effective low-energy three Higgs doublet model that may shed light on what underlies the observed fermion mass hierarchies and CKM mixing. We discuss possibilities for charged scalars coming from this model to show in collider experiments and show some interesting benchmark points.
|
|
| 7. |
- Camargo-Molina, José Eliel, et al.
(författare)
-
Heavy charged scalars from cs̄ fusion : a generic search strategy applied to a 3HDM with U(1) x U(1) family symmetry
- 2018
-
Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; :3
-
Tidskriftsartikel (refereegranskat)abstract
- We describe a class of three Higgs doublet models (3HDMs) with a softly broken U(1) x U(1) family symmetry that enforces a Cabibbo-like quark mixing while forbidding tree-level flavour changing neutral currents. The hierarchy in the observed quark masses is partly explained by a softer hierarchy in the vacuum expectation values of the three Higgs doublets. As a consequence, the physical scalar spectrum contains a Standard Model (SM) like Higgs boson h(125) while exotic scalars couple the strongest to the second quark family, leading to rather unconventional discovery channels that could be probed at the Large Hadron Collider. In particular, we describe a search strategy for the lightest charged Higgs boson H-+/-, through the process cs̄ -> H+ -> W+ h(125), using a multivariate analysis that leads to an excellent discriminatory power against the SM background. Although the analysis is applied to the proposed class of 3HDMs, we employ a model-independent formulation such that it can be applied to any other model with the same discovery channel.
|
|
| 8. |
- Camargo-Molina, José Eliel, et al.
(författare)
-
On a radiative origin of the Standard Model from trinification
- 2016
-
Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2016:9
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, we present a trinification-based grand unified theory incorporating a global SU(3) family symmetry that after a spontaneous breaking leads to a left-right symmetric model. Already at the classical level, this model can accommodate the matter content and the quark Cabbibo mixing in the Standard Model (SM) with only one Yukawa coupling at the unification scale. Considering the minimal low-energy scenario with the least amount of light states, we show that the resulting effective theory enables dynamical breaking of its gauge group down to that of the SM by means of radiative corrections accounted for by the renormalisation group evolution at one loop. This result paves the way for a consistent explanation of the SM breaking scale and fermion mass hierarchies.
|
|
| 9. |
- Camargo-Molina, José Eliel, et al.
(författare)
-
On a radiative origin of the standard model in non-supersymmetric trinification with global SU(3)F
- 2016
-
Ingår i: Proceedings of Science. - 1824-8039. ; Part F128560
-
Tidskriftsartikel (refereegranskat)abstract
- We present a trinification-based grand unified theory incorporating a global SU(3)F family symmetry, that after spontaneous symmetry breaking leads to a left-right symmetric model. In addition to unification of gauge couplings, the model unifies Yukawa interactions and contains equivalent representations in the scalar and fermion sectors at high energy scales. Considering the minimal low-energy scenario with the least amount of light states, we show that the resulting effective theory enables dynamical breaking of its gauge group to that of the Standard Model by means of radiative corrections accounted for by the renormalisation group evolution at leading order. This result paves the way for a possible explanation of the SM breaking scale and fermion mass hierarchies.
|
|
| 10. |
|
|
