Spectroscopy of SU(4) composite Higgs theory with two distinct fermion representations

Ayyar, Venkitesh; DeGrand, Thomas; Golterman, Maarten; Hackett, Daniel C.; Jay, Walter M.; Neil, Ethan T.; Shamir, Yigal; Svetitsky, Benjamin

doi:10.1103/physrevd.97.074505

Cited by 93 publications

(145 citation statements)

References 60 publications

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“…This is a novel area of exploration for lattice gauge theories, for which the literature is somewhat limited (see for instance Refs. [21,27,29,33,38]). New fermion bound states, sometimes referred to as chimera baryons, can be sourced by operators that involve gauge-invariant combinations of fermions in mixed representations.…”

Section: Discussionmentioning

confidence: 99%

“…The introduction of diagonal mass terms for the fermions is compatible (aligned) with the vacuum structure, and provides a degenerate non-vanishing mass for the resulting 5 + 20 pNGBs. The lattice treatment of such a system with multiple dynamical fermion representations is a novel arena for lattice gauge theories, and only recently have calculations of this type been published, in the specific context of theories with SU (4) gauge group [21,27,29,33,38].…”

Section: Contentsmentioning

confidence: 99%

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Sp(4) gauge theories on the lattice: Quenched fundamental and antisymmetric fermions

et al. 2020

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We perform lattice studies of meson mass spectra and decay constants of the Sp(4) gauge theory in the quenched approximation. We consider two species of (Dirac) fermions as matter field content, transforming in the 2-index antisymmetric and the fundamental representation of the gauge group, respectively. All matter fields are formulated as Wilson fermions. We extrapolate to the continuum and massless limits, and compare to each other the results obtained for the two species of mesons. In the case of two fundamental and three antisymmetric fermions, the long-distance dynamics is relevant for composite Higgs models. This is the first lattice study of this class of theories. The global SU (4) × SU (6) symmetry is broken to the Sp(4) × SO(6) subgroup, and the condensates align with the explicit mass terms present in the lattice formulation of the theory.The main results of our quenched calculations are that, with fermions in the 2-index antisymmetric representation of the group, the masses squared and decay constant squared of all the mesons we considered are larger than the corresponding quantities for the fundamental representation, by factors that vary between ∼ 1.2 and ∼ 2.7. We also present technical results that will be useful for future lattice investigations of dynamical simulations, of composite chimera baryons, and of the approach to large-N in the Sp(2N ) theories considered. We briefly discuss their high-temperature behaviour, where symmetry restoration and enhancement are expected. We acknowledge useful discussions withWe summarise in this Appendix our conventions in the treatment of spinors, which are useful, for example, in switching between the 2-component and the 4-component notation (see also Ref. [50]). The former is best suited to highlight the symmetries of the system, while the latter is the formalism adopted as a starting point for the lattice numerical

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Section: Discussionmentioning

confidence: 99%

Section: Contentsmentioning

confidence: 99%

Sp(4) gauge theories on the lattice: Quenched fundamental and antisymmetric fermions

et al. 2020

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“…Blue circles are for the models M6 and M12, while the red diamond is for the model M11 and the black square for the lattice SU (4) model considered in Refs. [21][22][23][24][25][26]. global symmetry breaking [21,23].…”

Section: Applications To Two-representation Composite Higgs Mod-elsmentioning

confidence: 99%

Into the conformal window: Multirepresentation gauge theories

2020

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We investigate the conformal window of four-dimensional gauge theories with fermionic matter fields in multiple representations. Of particularly relevant examples are the ultra-violet complete models with fermions in two distinct representations considered in the context of composite Higgs and top partial-compositeness. We first discuss various analytical approaches to unveil the lower edge of the conformal window and their extension to the multiple matter representations. In particular, we argue that the scheme-independent series expansion for the anomalous dimension of a fermion bilinear at an infrared fixed point, γχ χ, IR , combined with the conjectured critical condition, γχ χ, IR = 1 or equivalently γχ χ, IR (2−γχ χ, IR ) = 1, can be used to determine the boundary of conformal phase transition on fully physical grounds. In illustrative cases of SU (2) and SU (3) theories with N R Dirac fermions in various representations, we assess our results by comparing to other analytical or lattice results. *

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“…Details on the HMC algorithm, diquark operators and the fits of correlation functions are presented in Appendix A. We present our strategy and perform the continuum limit extrapolation by employing a mass-dependent prescription [85] introduced through the Wilson chiral perturbation theory (WχPT) [86,87] (see also Ref. [88], and the literature on improvement [89,90]), and report the results in Section 4.3.…”

Section: Introductionmentioning

confidence: 99%

Sp (4) gauge theories on the lattice: Nf = 2 dynamical fundamental fermions

Bennett

Hong

Lee

et al. 2019

J. High Energ. Phys.

135

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We perform lattice studies of the gauge theory with Sp(4) gauge group and two flavours of (Dirac) fundamental matter. The global SU (4) symmetry is spontaneously broken by the fermion condensate. The dynamical Wilson fermions in the lattice action introduce a mass that breaks the global symmetry also explicitly. The resulting pseudo-Nambu-Goldstone bosons describe the SU (4)/Sp(4) coset, and are relevant, in the context of physics beyond the Standard Model, for composite Higgs models. We discuss scale setting, continuum extrapolation and finite volume effects in the lattice theory. We study mesonic composite states, which span representations of the unbroken Sp(4) global symmetry, and we measure masses and decay constants of the (flavoured) spin-0 and spin-1 states accessible to the numerical treatment, as a function of the fermion mass. With help from the effective field theory treatment of such mesons, we perform a first extrapolation towards the massless limit. We assess our results by critically comparing to the literature on other models and to the quenched results, and we conclude by outlining future avenues for further exploration. The results of our spectroscopic analysis provide new input data for future phenomenological studies in the contexts of composite Higgs models, and of dark matter models with a strongly coupled dynamical origin. arXiv:1909.12662v2 [hep-lat] 22 Nov 2019 7 Comparison to other gauge theories 37 8 Continuum results: summary 42 9 Conclusions and outlook 43 A Lattice action and numerical calculations: additional details 45 A.1 Hybrid Monte Carlo 45 A.2 Of diquarks 47 A.3 Effective mass and fitting procedure 48 B Low-energy constants and global fit 50 -1 -

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Spectroscopy of SU(4) composite Higgs theory with two distinct fermion representations

Cited by 93 publications

References 60 publications

Sp(4) gauge theories on the lattice: Quenched fundamental and antisymmetric fermions

Sp(4) gauge theories on the lattice: Quenched fundamental and antisymmetric fermions

Into the conformal window: Multirepresentation gauge theories

Sp (4) gauge theories on the lattice: Nf = 2 dynamical fundamental fermions

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