Four-fermion decay of Higgs bosons

Asaka, Takashi; Hikasa, K.

doi:10.1016/0370-2693(94)01599-8

Cited by 5 publications

(6 citation statements)

References 18 publications

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“…The results of Refs [8],[16]. →[18] will still apply to other models in which a fermiophobic H ±± , H ± or H 0 exists.…”

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confidence: 86%

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Cascade decays of triplet Higgs bosons at LEP2

Akeroyd¹

1998

Physics Letters B

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We study the Georgi-Machacek two triplet, one doublet model in the context of LEP2, and show that cascade decays of Higgs bosons to lighter Higgs bosons and a virtual vector boson may play a major role. Such decays would allow the Higgs bosons of this model to escape current searches, and in particular are of great importance for the members of the five-plet which will always decay to the three-plet giving rise to cascade signatures.

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“…The results of Refs [8],[16]. →[18] will still apply to other models in which a fermiophobic H ±± , H ± or H 0 exists.…”

mentioning

confidence: 86%

“…Assuming that the five-plet members are the lightest, Refs. [8], [16] → [18] consider the decay channels of H 0 5 , H ±± 5 and H ± 5 . They conclude that for M 5 in range at LEP2 one would find…”

Section: The Higgs Triplet Model (Htm)mentioning

confidence: 99%

Cascade decays of triplet Higgs bosons at LEP2

Akeroyd¹

1998

Physics Letters B

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“…Here and in the following, we neglect interference terms of five-point amplitudes with a single fermion trace, since, in the kinematic regime of interest here, these are strongly suppressed, by Γ V /M V , with V = W, Z. Such terms have recently been included in a tree-level calculation of Γ(H → 2V → 4f ) for M H ≪ M W [35]. The correction factor for case (3) is slightly more complicated because the electron and positron lines run from the initial state to the final state.…”

Section: Corrections From the Gauge Sectormentioning

confidence: 99%

Three-loop O(αs2GFMt2) corrections to Higgs production and decay at e+e− colliders

Kniehl

Steinhauser

1995

Nuclear Physics B

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We evaluate the next-to-leading-order QCD corrections of O(α 2 s G F M 2 t ) to the Standard-Model ℓ + ℓ − H, ZZH, and W + W − H couplings in the heavy-top-quark limit. Exploiting these results together with knowledge of ∆ρ to the same order, we analyze a variety of production and decay processes of low-mass Higgs bosons at e + e − colliders. Specifically, we considerWe work in the electroweak on-shell scheme formulated with G F and employ both the on-shell and MS definitions of the top-quark mass in QCD. As expected, the scheme and scale dependences are greatly reduced when the next-to-leading-order corrections are taken into account. In the on-shell scheme of top-quark mass renormalization, the O(α 2 s G F M 2 t ) corrections act in the same direction as the O(α s G F M 2 t ) ones and further increase the screening of the O(G F M 2 t ) terms. The coefficients of (α s /π) 2 range from −6.847 for the ZZH coupling to −16.201 for the ℓ + ℓ − H coupling. This is in line with the value −14.594 recently found for ∆ρ.

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“…Here and in the following, we neglect interference terms of five-point amplitudes with a single fermion trace, since these are strongly suppressed, by Γ V /M V , with V = W, Z. Such terms have recently been included in a tree-level calculation of Γ(H → 2V → 4f ) for M H ≪ M W [34]. The formulas become slightly more complicated if a fermion line runs from the initial state to the final state, e.g., in the case of ZZ fusion.…”

Section: One-loop Resultsmentioning

confidence: 99%

Two-loopO(αsGFMQ2
Kniehl
¹

1996
Phys. Rev. D
13
0
16
0
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By means of a low-energy theorem, we analyze at O(α s G F M 2 Q ) the shifts in the Standard-Model W + W − H and ZZH couplings induced by virtual high-mass quarks, Q, with M Q ≫ M Z , M H , which includes the top quark. Invoking the improved Born approximation, we then find the corresponding corrections to various four-and fivepoint Higgs-boson production and decay processes which involve the W + W − H and ZZH vertices with one or both of the gauge bosons being connected to light-fermion currents, respectively. This includes e + e − → ffH via Higgs-strahlung, via W + W − fusion (with f = ν e ), and via ZZ fusion (with f = e), as well as H → 2V → 4f (with V = W, Z).1 exploiting the Higgs-strahlung mechanism [3,4], e + e − → ZH → ff H. In next-generation e + e − linear supercolliders (NLC), also e + e − → ν eνe H via W + W − fusion and, to a lesser extent, e + e − → e + e − H via ZZ fusion will provide copious sources of Higgs bosons.The study of quantum corrections to the production and decay processes of the Higgs boson has received much attention in the literature; for a review, see Ref. [5]. Since the top quark, with pole mass M t = (180 ± 12) GeV [6], is so much heavier than the intermediate bosons, the M t -dependent corrections are particularly important. On the other hand, it is attractive to consider the extension of the SM by a fourth fermion generation, where such corrections may be even more significant. Some time ago, Hill and Paschos [7] proposed an interesting fourth-generation scenario with Majorana neutrinos, which exploits the see-saw mechanism to evade the LEP1/SLC constraint on the number of light neutrinos. The novel charged fermions of this model are assumed to be of Dirac type and to have standard couplings. Subsequently, this model was further elaborated, and the precise triviality bounds, renormalization-group fixed points, and related dynamical mechanisms were discussed [8].In particular, it was demonstrated how this model is reconciled with the fermion-mass constraints established in Ref. [9]. In Ref.[10], it was shown that this model is compatible with precision data from low energies and LEP1/SLC. Very recently, it was noticed [11] that arguments favouring the presence of a fourth fermion generation may be adduced on the basis of the democratic mass-matrix approach [12]. The possible existence of a fourth fermion generation is also considered in the latest Particle Data Group Report [13], where mass bounds are listed. For a recent model-independet analysis, see Ref. [14].It is advantageous to trace such novel fermions via their loop effects in the Higgs sector, since these effects are also sensitive to mass-degenerate isodoublets via fermion-mass power corrections. This has originally been observed in Ref. [15] in connection with the ff H, W + W − H, and ZZH couplings. Moreover, the ggH coupling may serve as a device to detect mass-degenerate isodoublets of ultraheavy quarks [16], although power corrections do not occur here. By contrast, in the gauge sector, power corrections only appe...

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Four-fermion decay of Higgs bosons

Cited by 5 publications

References 18 publications

Cascade decays of triplet Higgs bosons at LEP2

Cascade decays of triplet Higgs bosons at LEP2

Three-loop O(αs2GFMt2) corrections to Higgs production and decay at e+e− colliders

Two-loopO(αsGFMQ2
Kniehl
¹

1996
Phys. Rev. D
13
0
16
0
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Four-fermion decay of Higgs bosons

Cited by 5 publications

References 18 publications

Cascade decays of triplet Higgs bosons at LEP2

Cascade decays of triplet Higgs bosons at LEP2

Three-loop O(αs2GFMt2) corrections to Higgs production and decay at e+e− colliders

Two-loopO(αsGFMQ2Kniehl1 1996Phys. Rev. D130160View full textAdd to dashboardCite

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Two-loopO(αsGFMQ2
Kniehl
¹

1996
Phys. Rev. D
13
0
16
0
View full text Add to dashboard Cite