Explanation for why the Early Universe was Stable and Dominated by the Standard Model. (arXiv:1911.04648v3 [hep-ph] UPDATED)

<a href="http://arxiv.org/find/hep-ph/1/au:+Hertzberg_M/0/1/0/all/0/1">Mark P. Hertzberg</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Jain_M/0/1/0/all/0/1">Mudit Jain</a>

The Standard Model (SM) possesses an instability at high scales that would be

catastrophic during or just after inflation, and yet no new physics has been

seen to alter this. Furthermore, modern developments in quantum gravity suggest

that the SM degrees of freedom are not unique; that a typical low energy

effective theory should include a large assortment of hidden sector degrees of

freedom. It is therefore puzzling that cosmological constraints from BBN and

CMB reveal that the early universe was almost entirely dominated by the SM,

when the inflaton $phi$ could have decayed into many sectors. In this work we

propose the following explanation for all of this: we allow the lowest

dimension operators with natural coefficients between the inflaton and both the

Higgs and hidden sectors. Such hidden sectors are assumed to be entirely

natural; this means all unprotected masses are pushed up to high scales and

project out of the spectrum, while only massless (or protected) degrees of

freedom remain, and so the inflaton can only reheat these sectors through

higher dimension (and suppressed) operators. On the other hand, the SM

possesses a special feature: it includes a light Higgs $H$, presumably for life

to exist, and hence it allows a super-renormalizable coupling to the inflaton

$phi H^dagger H$, which allows rapid decay into the SM. We show that this

naturally (i) removes the instability in the Higgs potential both during and

after inflation due to a tree-level effect that increases the value of the

Higgs self-coupling from the IR to the UV when one passes the inflaton mass,

(ii) explains why the SM is dominant in the early universe, (iii) allows dark

matter to form in hidden sector/s through subsequent dynamics (or axions, etc),

(iv) allows for high reheating and baryogenesis, and (v) accounts for why there

so far has been no direct detection of dark matter or new physics beyond the

SM.

The Standard Model (SM) possesses an instability at high scales that would be

catastrophic during or just after inflation, and yet no new physics has been

seen to alter this. Furthermore, modern developments in quantum gravity suggest

that the SM degrees of freedom are not unique; that a typical low energy

effective theory should include a large assortment of hidden sector degrees of

freedom. It is therefore puzzling that cosmological constraints from BBN and

CMB reveal that the early universe was almost entirely dominated by the SM,

when the inflaton $phi$ could have decayed into many sectors. In this work we

propose the following explanation for all of this: we allow the lowest

dimension operators with natural coefficients between the inflaton and both the

Higgs and hidden sectors. Such hidden sectors are assumed to be entirely

natural; this means all unprotected masses are pushed up to high scales and

project out of the spectrum, while only massless (or protected) degrees of

freedom remain, and so the inflaton can only reheat these sectors through

higher dimension (and suppressed) operators. On the other hand, the SM

possesses a special feature: it includes a light Higgs $H$, presumably for life

to exist, and hence it allows a super-renormalizable coupling to the inflaton

$phi H^dagger H$, which allows rapid decay into the SM. We show that this

naturally (i) removes the instability in the Higgs potential both during and

after inflation due to a tree-level effect that increases the value of the

Higgs self-coupling from the IR to the UV when one passes the inflaton mass,

(ii) explains why the SM is dominant in the early universe, (iii) allows dark

matter to form in hidden sector/s through subsequent dynamics (or axions, etc),

(iv) allows for high reheating and baryogenesis, and (v) accounts for why there

so far has been no direct detection of dark matter or new physics beyond the

SM.

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