## Thursday, September 12, 2013 ... /////

### Luminogenesis and permanent dark matter domination

Creativity in a prison: Paul Frampton co-writes a new paper

The latest 2013 Planck data tell us that about 68% of the averaged energy density $\overline{T_{00}}$ in the Universe is composed of dark energy (as far as we can say, it's a positive cosmological constant), 27% is dark matter, and 5% is visible matter.

For a few billion years, "we" have been gradually entering the cosmological-constant-dominated era. The percentage of dark energy will converge towards 100% as the remaining types of matter will be diluted. The absolute magnitude of the energy density carried by the cosmological constant has been and will be constant; that's why the cosmological constant is called a constant. The energy density carried by other components decreases as $1/a(t)^n$ for various exponents $n$ which means that they are guaranteed losers at the end.

In the future, the expansion of the Universe will be approximately exponential; the linear dimensions of the Universe (distances between galaxies) will double each 10 billion years or so. The future is bound to be ever more boring and the global cooling will continue exponentially. The cosmological constant is essential for this future boredom; however, dark matter was much more important for the structure formation etc.

For your convenience, I will begin with the list of "epochs" in cosmology – i.e. the biography of our Universe. The abbreviation ATB means [some cosmic proper time] "After The [Big] Bang". The acronym ATB may be used just like AD; however, the birth of Jesus Christ is replaced by a comparably important event, the Big Bang.

The usual epochs are as follows:

• Before the Big Bang? This part of the history may have existed (if e.g. eternal inflation is true etc.) but it may have been absent.

• Planck epoch: $0$ ATB – $10^{-43}\,{\rm sec}$ ATB: quantum gravity is paramount for this ultrashort, marginally unphysical, period

• Grand unified epoch: $10^{-43}\,{\rm sec}$ ATB – $10^{-36}\,{\rm sec}$ ATB: the temperature $kT$ of the Universe dropped from the Planck scale beneath the GUT scale $10^{15}\GeV$; at the end, the forces (probably the 3 gauge groups of the Standard Model) crystallized out of their previously dominant union

• Electroweak epoch: $10^{-36}\,{\rm sec}$ ATB – $10^{-12}\,{\rm sec}$ ATB: the temperature drops from the GUT scale to the electroweak scale $100\GeV$; some interesting eras probably belong here:

• Inflationary epoch: It's not quite clear when it began (in the electroweak epoch) but the Universe was exponentially increasing in size as a function of time; at least $\exp(60)$ times; the expansion is similar to the expansion due to the cosmological constant today but it was much faster due to much higher effective cosmological constant (potential energy of inflaton field)

• Reheating: The inflating Universe was brutally cooling down but when the inflaton dropped near the minimum, the kinetic energy of the inflaton field got converted to other fields, quanta were created, and the temperature heated up again

• Baryogenesis: Sometimes later, again, the timing is unknown, baryons and antibaryons were produced and there had to be a slight excess of the baryons so that they're still around after most of the matter annihilated

• Quark epoch: $10^{-12}\,{\rm sec}$ ATB – $10^{-6}\,{\rm sec}$ ATB: the temperature was dropping from the electroweak scale to the QCD scale $100\MeV$ and quarks were organized in quark-gluon plasma

• Hadron epoch: $10^{-6}\,{\rm sec}$ ATB – $10^{-5}\,{\rm sec}$ ATB: quarks cooled down enough to create individual hadrons; at the end, the temperature wasn't high enough for hadron pairs to be pair-produced

• Lepton epoch: $1-10\,{\rm sec}$ ATB: lots of lepton-antilepton pairs produced; at the end, the temperature wasn't high enough for that anymore

• Photon epoch: $10\,{\rm sec}$ ATB – $380,000\,{\rm years}$ ATB: photons and/or baryons dominated the energy of the Universe; it has subepochs:

• Big Bang Nucleosynthesis: The First Three Minutes ATB, as Weinberg called them in the title of his book; nuclei were produced out of the hadrons according to some thermal rules; the theory-predicted relative abundance of many light isotopes nicely agrees with observations

• Radiation-dominated era: Ends about $70,000\,{\rm years}$ ATB when the energy carried by baryons matches the energy carried by photon

• Matter-dominated era: $70,000\,{\rm years}$ ATB – $380,000{\rm years}$ ATB: baryons have the majority in energy density

• Recombination (photon decoupling): $380,000\,{\rm years}$ ATB: electrons finally cool down enough to sit at the atomic orbits; plasma turns into gas, the Universe becomes almost transparent

• Dark ages: Lasts for something between 0.15 and 0.8 billion years; the only visible spectral line from this era is the 21-centimeter spin line of hydrogen

• Reionization: After the dark ages, the temperature grew because of the objects that were created and stole some energy from gravity; the hydrogen atoms became ionized plasma again
OK, this was a brief history of our universe which had almost nothing to do with the new paper by Paul H. Frampton and Pham Q. Hung,
Luminogenesis from Inflationary Dark Matter
While the usual cosmology has various epochs – matter-dominated epochs and radiation-dominated epochs – the authors conjecture that dark matter was dominant (except for the dark energy, I suppose) throughout the history of the Universe. They achieve this outcome by a "new kind of unification". More precisely, the grand unified group usually embeds $SU(3)_c\times SU(2)_W\times U(1)_Y$ into a larger, simpler group. Paul and Pham extend $SU(2)_W$ to a larger group, namely $SU(6)$, which is large enough to contain some new particles that play the role of the dark matter. The representations ${\bf 6}$, ${\bf 20} = {\bf 6}\wedge {\bf 6}\wedge {\bf 6}$ (antisymmetric tensor with three indices), and ${\bf 35}={\bf 6}\otimes{\bf 6}-{\bf 1}$ (adjoint). Their cosmological model creates the dark matter in "dark matter genesis" and later, they must produced the visible matter by "luminogenesis". How did lumogenesis work? Why don't you ask my parents what they were doing about 4 decades ago? Oops, it's "luminogenesis", not "lumogenesis". ;-) You will find the answers in the paper. Paul wrote me something that's at least as interesting to read as the paper itself:

Hello Lubos, Here is a paper on an alternative and plausible theory of the early universe starting from only dark matter..

Apart from everything else, it answers for me a forty-year-old question of why did $SU(5)$ fail in predicting correctly the proton decay lifetime? It may precede your professional involvement but I can tell you that at Harvard and throughout the particle theory community for the years roughly 1979-1984 (the $SU(5)$ paper of Georgi-Glashow was 1974 but nobody took it seriously until 1979) a clear majority believed in it. It was said that its confirmation by experiment would make Shelly as famous as Einstein, probably true! And maybe Howard as famous as Shelly and at least Howard received a well-deserved Harvard tenure partly on its basis. Only in 1984 did the IMB experiment, first announced at the Fifth Workshop on Grand Unification (FWOGU) at Brown University, show convincingly that the proton lifetime is at least 100 times the $SU(5)$ prediction. It came as a shock to me as the theory had seemed so simple, convincing, and economical.

Why was it wrong? Because it included only luminous matter and omitted dark matter!!

In the specific model of 1309.1723, and it surely applies more generally, there is no luminous matter above the luminogenesis (a new word, I believe) scale so the renormalization group flows are significantly changed. We are studying this.

Dark matter is all there is at earlier times or higher temperatures than $10^9\GeV$ which I believe is a generic luminogenesis scale.

I cannot end without mentioning string theory! A goal of string phenomenology is often to arrive at a GUT or SusyGUT. This may be misguided. The goal should instead be a DUT or SusyDUT where DUT = Dark Unified Theory.

I hope this paper provides at least mild titillation?

All good wishes from an about-weekly TRF reader. I hope everything goes well in Pilsen, if that is still where you live. Best regards from your friend [...]

I hope it's OK to post it.

It's all very intriguing; I like similar group-theoretical games, especially if they seem to work. However, I remain unconvinced that dark matter embedded in DUT is the only – or most convincing – way to fix the failures of the minimal GUT theory. And I am completely agnostic whether it is natural to assume that the dark matter dominates "at all times". The Universe may work in both ways and because the "uniformity" of the matter that dominates isn't even a starting assumption of a theory but a result derived from a theory's dynamics, I think it's a typical question that a theorist should be open-minded about.

But read the paper. I hope that it will provide at least mild titillation.

#### snail feedback (11) :

Lumo did you hack my mind :-(0) ...?!

Just this morning I was wondering how and what Prof. Frampton is doing ... :-D

I can't hack minds but Paul probably can, ;-) I read the paper because he sent me an e-mail today.

Six epochs in the blink of an eye!

That is a very nice and interesting post :-)

The sentences

"A goal of string phenomenology is often to arrive at a GUT or SusyGUT.
This may be misguided. The goal should instead be a DUT or SusyDUT where
DUT = Dark Unified Theory."

make me wonder if and how the new ideas in the paper go along with string theory...?

Lumo, I respect you intellect enormously, but dark matter and energy have, to me, all the look and feel of a kludge. We may have an incomplete understanding of gravity, which could better explain the variation between currently accepted theory and observation better than inventing unobservable forces to make the theory fit with observation.

That being said, if the nymph you pictured is an advocate of dark energy and matter, Count me in!

I have same thoughts on DM & DE. In the matter of fact, I created a model where those two are not needed.

Is that lady the same one who lured mr. Frampton?

Dear Dilaton, Paul cared about it but couldn't settle the question.

Those groups, however, could be "unusually" embedded in the heterotic gauge group - within the same E8. For example, extend the SU(6) or SU(6) x U(1) to E6 and you get SU(3) x E6 but with a different E6 than normally envisioned - they noncommutatively "overlap". I haven't checked the spectrum etc. because I still don't understand the motivation behind or evidence for the model well.

Yup, it's the same Czech-born model.