Alternative "Higgsless" models would have been considered if the Higgs boson was not discovered

Question

In the Standard Model, the Higgs particle is a boson with no spin, electric charge, or color charge. It is also very unstable, decaying into other particles almost immediately. It is a quantum excitation of one of the four components of the Higgs field. The latter constitutes a scalar field, with two neutral and two electrically charged components, and forms a complex doublet of the weak isospin SU(2) symmetry. The field has a "Mexican hat" shaped potential with nonzero strength everywhere (including otherwise empty space), which in its vacuum state breaks the weak isospin symmetry of the electroweak interaction. When this happens, three components of the Higgs field are "absorbed" by the SU(2) and U(1) gauge bosons (the "Higgs mechanism") to become the longitudinal components of the now-massive W and Z bosons of the weak force. The remaining electrically neutral component separately couples to other particles known as fermions (via Yukawa couplings), causing these to acquire mass as well. Some versions of the theory predict more than one kind of Higgs fields and bosons. Alternative "Higgsless" models would have been considered if the Higgs boson was not discovered.

-- http://en.wikipedia.org/wiki/Higgs_boson

I don't know what to make of the last sentence in bold.

I thought it should be: Alternative "Higgsless" models would have been considered if the Higgs boson had not been discovered". But it didn't agree with the context.

According to PEU¹ 259.3, maybe it's an example in which "would have done" is employed to talk about present and future situations which are no longer possible because of the way things have turned out.

Please help to clarify this.

^{1. PEU = Michael Swan's, Practical English Usage.}

Answer 1

Strictly speaking, OP's cited text does indeed contain a verb tense inconsistency - the "consistent" form is "X would have happened if Y had happened" (with negations as appropriate).

But it's not a glaring inconsistency (at least, not to me). It's certainly nowhere near bad enough to suggest that the writer is "uneducated", or perhaps not even a native speaker.

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To at least some speakers, the Simple Past (happened, as opposed to Past Perfect had happened) is probably more acceptable when the truth/falsity of the condition is unknown. In OP's example we know the Higgs boson has been discovered, but consider these similar usages...

1: "He would have arrived by noon unless he missed the train"
1a: "He would have arrived by noon unless he has missed the train"
2: ? "He would have arrived by noon unless he had missed the train"
3: "At one o'clock I told them that he would have arrived by noon unless he missed the train"
4: ? "At one o'clock I told them that he would have arrived by noon unless he had missed the train"

Personally, I have no real objection to any of the above, but I find #2 and #4 slightly less "elegant" (there's no good reason to introduce the "past within the past" in #2, but there definitely is in #4).

Answer 2

The sentence would have been more clear with the proper punctuation:

Alternative, "Higgs-less" models would have been considered if the Higgs boson was not discovered.

In this case alternative and Higgsless are both adjectives.