Two viable large scalar multiplet models with a<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>Z</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>symmetry

Earl, Kevin; Hartling, Katy; Logan, Heather E.; Pilkington, Terry

doi:10.1103/physrevd.90.055029

Cited by 12 publications

(24 citation statements)

References 72 publications

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“…, (5.2) so we see that there are 11 independent operators at the dimension-4 level. 3 As a side note, the field and group representation content for this example is simple enough that the closed form for the unrefined Hilbert series can be calculated. The result is…”

Section: Hilbert Series For Bsmmentioning

confidence: 97%

“…One common way to augment the complexity of a model is to simply add particles transforming under higher-dimensional group representations. For some representative examples using sizable group representations in phenomenological settings, see [1][2][3][4][5] and references therein. In addition to complex model building, another line of attack in the search for new physics takes a general bottom-up approach -parameterizing BSM effects through higher dimensional operators formed from SM fields.…”

Section: Introductionmentioning

confidence: 99%

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Hilbert series for constructing Lagrangians: Expanding the phenomenologist’s toolbox

2015

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This note presents the Hilbert series technique to a wider audience in the context of constructing group-invariant Lagrangians. This technique provides a fast way to calculate the number of operators of a specified mass dimension for a given field content, and is a useful cross check on more well-known group theoretical methods. In addition, at least when restricted to invariants without derivatives, the Hilbert series technique supplies a robust way of counting invariants in scenarios which, due to the large number of fields involved or to high dimensional group representations, are intractable by traditional methods. We work out several practical examples.

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Section: Hilbert Series For Bsmmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Hilbert series for constructing Lagrangians: Expanding the phenomenologist’s toolbox

2015

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“…The SM is also a non-abelian gauge theory, meaning that the Lagrangian which describes the interactions of the subatomic particles is locally gauge invariant 6 under a certain symmetry group, SU(3) c × SU(2) L × U (1) Y [45,46]. It is non-abelian because the generators of the SU (3) and SU (2) sectors are non-commutative. The 5 The SM does not include gravity.…”

Section: The Gauge Sectormentioning

confidence: 99%

“…or more electroweak scalar multiplets of size n ≥ 3. In particular, it will consider two classes of models with large inert multiplets of size n ≥ 5 [2,3], as well as the Georgi-Machacek model (GM), which includes scalar triplets [30,70]. We will focus on the ability of these models to provide explanations and benchmarks for dark matter, exotic scalars, and altered Higgs couplings.…”

Section: Bsm Scalar Extensionsmentioning

confidence: 99%

“…By separating the interactions based on their symmetry group, we may obtain a bound on Y in terms of n from the U (1) Y amplitudes, and an independent bound on n from the SU(2) L amplitudes. We will therefore work in the 3 bosons. The gauge interactions of the scalars will arise from the following scalar gauge-kinetic terms,…”

Section: A Model With An Extra Scalar Multipletmentioning

confidence: 99%

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Theoretical and Experimental Constraints on Large Electroweak Scalar Multiplets

Hartling¹

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We apply theoretical and experimental constraints to models that extend the Standard Model (SM) with scalar electroweak SU(2) L multiplets of isospin T ≥ 1.Using tree-level perturbative unitarity, we determine that such multiplets may have a maximum weak isospin T ≤ 7/2 (4) if they are complex (real). We also determine an upper bound on the hypercharge of a scalar SU(2) L multiplet as a function of its size n = 2T + 1. Using these bounds, we study two classes of models which extend the SM by a single scalar SU(2) L multiplet of isospin T ≥ 2 and which preserve an additional U (1) or Z 2 symmetry. By applying bounds from precision electroweak measurements, Higgs decays to two photons, and dark matter direct-detection, we determine that the U (1) models with isospin T = 5/2, 3, 7/2 are excluded. The Z 2 models remain viable, but can account for at most 1% of the dark matter in the universe at masses below 1 TeV.We also study the most general scalar potential of the Georgi-Machacek model, which extends the SM with two electroweak scalar triplets. We show that this model possesses a decoupling limit, and that in this limit the deviations of the Higgs couplings to vector bosons from their SM values may be larger and of opposite sign to those of the Two Higgs Doublet Model. We apply constraints from perturbativity, vacuum stability, electroweak precision observables, and B-physics, and demonstrate their effects on the model parameter space with numerical scans. We show thatsubject to these constraints -the Georgi-Machacek (GM) model can simultaneously enhance all of the Higgs couplings to Standard Model particles by up to 18%, corresponding to a 39% enhancement of all Higgs production modes. Finally, we derive general formulas for loop decays of the GM scalars to γγ, Zγ, and W + γ, and consider their effects on the scalar branching ratios in a benchmark case.ii

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Dark matter semi-annihilation for inert scalar multiplets

Beauchesne,

Chiang

2024

J. High Energ. Phys.

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Dark matter semi-annihilation is a process through which two dark matter candidates annihilate to a single dark matter particle and a non-dark matter particle. Such processes are common when the symmetry stabilizing the dark matter differs from ℤ2 and can lead to qualitatively different phenomenology. In this work, we study the viability of semi-annihilation models including one or two inert multiplets. For one multiplet, we show that there does not exist any viable model in which semi-annihilation is efficient. For two multiplets, semi-annihilation can be efficient, but the number of viable and technically natural models is limited. We then perform a detailed study of the most promising model, showing that the correct relic abundance can be obtained for a wide range of masses.

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Two viable large scalar multiplet models with aZ2symmetry

Cited by 12 publications

References 72 publications

Hilbert series for constructing Lagrangians: Expanding the phenomenologist’s toolbox

Hilbert series for constructing Lagrangians: Expanding the phenomenologist’s toolbox

Theoretical and Experimental Constraints on Large Electroweak Scalar Multiplets

Dark matter semi-annihilation for inert scalar multiplets

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