Higgs boson decays to dark photons through the vectorized lepton portal

Non-Abelian dark gauge forces that do not couple directly to ordinary matter may be realized in nature. The minimal form of such a dark force is a pure Yang-Mills theory. If the dark sector is reheated in the early universe, it will be realized as a set of dark gluons at high temperatures and as a collection of dark glueballs at lower temperatures, with a cosmological phase transition from one form to the other. Despite being dark, the gauge fields of the new force can connect indirectly to the Standard Model through non-renormalizable operators. These operators will transfer energy between the dark and visible sectors, and they allow some or all of the dark glueballs to decay. In this work we investigate the cosmological evolution and decays of dark glueballs in the presence of connector operators to the Standard Model. Dark glueball decays can modify cosmological and astrophysical observables, and we use these considerations to put very strong limits on the existence of pure non-Abelian dark forces. On the other hand, if one or more of the dark glueballs are stable, we find that they can potentially make up the dark matter of the universe.

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“…In particular, at d = 8 the operator of Eq. [39,40,71]. The effective Lagrangian generated by integrating the fermions out is [39]…”

Section: A Dimension-8 Operatorsmentioning

confidence: 99%

Cosmological bounds on non-Abelian dark forces

2018

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“…[6,7,8,9], Higgs-portal dark matter models in Refs. [10,11,12,13,14], gauge-coupling unification in Refs. [15,16,17,18,19], neutrino mass generation and vacuum stability in Refs.…”

Section: Introductionmentioning

confidence: 99%

Higgs vacuum stability with vectorlike fermions

Gopalakrishna

Velusamy

2019

Phys. Rev. D

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We present the effects of vector-like fermions (VLF) on the stability of the Higgs electroweak vacuum, using the renormalization group improved Higgs effective potential. We review the calculation of the one-loop beta-functions of the standard model couplings paying particular attention to the fermion contributions. From this, we derive the VLF contributions to the betafunctions. We also include the significant two-loop contributions to the beta-functions. Using these beta-functions, we determine the scale at which the effective Higgs quartic-coupling becomes zero and goes negative, signaling vacuum instability. We find that for certain VLF masses and Yukawa couplings, the Higgs quartic stays positive for field values all the way up to the Planck scale, implying that the meta-stable vacuum of the standard model can be rendered absolutely stable if VLFs are present with certain parameters. For other values of VLF parameters, the Higgs vacuum is metastable as in the standard model. For cases where the vacuum is metastable, we compute the probability of quantum tunneling from the false electroweak vacuum into a deeper true vacuum in our Hubble volume by numerically solving for the bounce configuration in Euclidean space-time and computing the bounce action for it. We compare our numerical solution with the analytical approximation for the bounce action commonly used in the literature, and comment on when the latter may be used. * shri@imsc.res.in † arunprasath@imsc.res.in arXiv:1812.11303v3 [hep-ph] 13 Jul 2019Denoting the field value as h ≡ µ and denoting λ eff (µ) as just λ(µ), it can be shown (see for example Ref. [41]) that λ(µ) obeys a renormalization group equation (RGE) of the formThe RGE is interpreted now as an evolution with field value h = µ, and the β-function β λ is the usual β-function for the coupling λ, governed by the RGE. The λ(µ) obtained by integrating the RGE has the leading logs of the form log n (µ/M ) resummed. β λ is shown as a function of λ itself, and also of the other couplings that contribute significantly, which, in the SM, are the top Yukawa coupling y t and the SU (3), SU (2), U (1) gauge couplings g a = {g 3 , g 2 , g 1 }. All these couplings also evolve with µ via analogous RGE equations with their corresponding β-functions β yt , β ga . We neglect the contributions of the other SM couplings to the β-functions as they contribute insignificantly. From Eq.(3) we see that for h m h , the instability is signalled by the Higgs quartic effective coupling λ(µ) becoming negative.As we show explicitly later, β λ obtains a negative contribution from y t , while it obtains a positive contribution from λ(µ) itself and from gauge couplings. Thus, the top quark has the important effect of decreasing λ(µ), and for y t as large as in the SM, for the observed m h , it drives λ(µ) negative at higher energies, signaling vacuum instability. The effect of fermions coupled to the Higgs is generally to destabilize the electroweak vacuum, although in this work we show that this statement is not so definit...

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“…It turns out that the specific decays into lepton jets we explore in this work have not been searched for experimentally [23], although previous works on different mechanisms of the Higgs boson decaying into related final states can be found in Refs. [24][25][26][27][28][29]. On the other hand, the long-lived decay is relatively unexplored territory for the 125 GeV Higgs boson, except in Refs.…”

Section: Introductionmentioning

confidence: 99%

Higgs portal to dark QED

2020

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We introduce a light dark photon A 0 μ to the minimal Higgs portal model, by coupling the Higgs boson to "dark QED" containing fermionic dark matter, which gives rise to rich and interesting collider phenomenology. There are two prominent features in such a simple extension-the Higgs boson could have decays into the long-lived dark photon through the "mono-A 0 channel," or into multiple collimated leptons via "darkonium," depending on the mixing parameter of the A 0 μ with the visible photon. We initiate a study on the possibility of probing the parameter space of the model in both the energy and the lifetime frontiers at the Large Hadron Collider.

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Higgs boson decays to dark photons through the vectorized lepton portal

Cited by 12 publications

References 129 publications

Cosmological bounds on non-Abelian dark forces

Cosmological bounds on non-Abelian dark forces

Higgs vacuum stability with vectorlike fermions

Higgs portal to dark QED

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