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Primordial nucleosynthesis and New Physics

Maxim PospelovUniversity of Victoria and Perimeter Institute

K. Jedamzik and M. Pospelov, arXiv:0906.2087R. Cyburt and M. Pospelov, arXiv:0906.4373 

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Outline of the talk

1. Current status of Big Bang Nucleosynthesis.2. Lithium problem. Possible solutions. 3. Particle decay/annihiliation after the BBN.4. Catalyzed BBN. 5. Conclusions.

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BBN and Particle Physics

.0other ; conditions Initial less;or MeV ~ reactants ofEnergy

......)(

inp

kjijkii

nnn

nnvdTdnTTH

dtdn

Particle physics can 1. Affect the timing of reactions,

via e.g. new thermal degrees of freedom 2. Introduce non-thermal channels e.g. via late decays or annihilations

of heavy particles, E À T.3. Provide catalyzing ingredients that change hijkvi (MP, 2006).

Possible catalysts: electroweak scale remnants charged under U(1) or color SU(3) gauge groups. Relevant for charged NLSP-gravitino LSP scenario.

extrafermion

extrabosoneff

Pl

22/1

eff 8732

872 ;const)( NNN

MTNTH

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Elemental Abundance

A<1,2,3,4,7 – BBN; A>12 –Stars; A=6,9,10,11 –“orphans” (cosmic ray spallation)

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BBN abundance curves

n/p freeze-outDeut. bottleneckAll nuclear rates drop <Hubble

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Non-thermal change of elemental abundances due to late time energy injection

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Catalyzed Production of 6Li and 9Be at 8 KeV, suppression of 7Be+7Li at 35 KeV

Day 1, 5:25a.m. 0:03a.m. 9Be

6Li

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SBBN, current Status (Cyburt, Fields, Olive 2008)Theoretical predictions of abundances as functions of b Yellow band: WMAP-suggested input for baryon to photon ratio b =6.14 10-10

7Be branch

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The fraction of energy density in baryons is measured rather precisely,

No more wiggle room with b for BBN.

2. There is a noticeable tension between predicted and observed amounts of 7Li,

A. Measurements have an unaccounted systematic error. B. We do not understand the cycling of 7Li in stars.

What we see is not primordial. C. Calculations (e.g. nuclear rates) are wrong.D. New Physics interference. What kind of new physics?

4. Unexpected 6Li problem? Not yet...

Lithium problem

1010)17.023.6( b

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Deuterium and Lithium abundances

Coc et al, ApJ 2004

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Possible astrophysical resolution of 7Li discrepancy

There is a growing suspicion that pop II stars can themselves deplete lithium by admixing it from the atmospheres into a hot interrior where it gets destroyed (Korn et al., 2006, employs diffusion and extra mixing).

Can it provide a factor of 2-3 suppression? Can the suppression work uniformly along the Spite plateau,

without introducing extra scatter? Would the measured abundances of other elements be OK?

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Emerging 6Li problem?A lot of speculations about primordial 6Li!

Unexpected plateau (?) of 6Li with metallicity (Asplund et al., 2005)

6Li/H ~ 2 £ 10-11

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9Be vs metallicityThere is no evidence for primordial values

No serious BBN models ever predicted anything in excess of 10-15

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More on 7Li generation during the BBNIn fact, it is 7Li+7Be that we are interested in (much later, 7Be

captures an electron and becomes 7Li). Things are simple: there is one reaction in, and one reaction out

3He+ ! 7Be + - IN. 7Be +n ! p +7Li – OUT, (followed by 7Li+p ! 2)At T>25 keV, 7Li is unstable being efficiently burned by protons. 4He, 3He, D, p, and n can be all considered as an input for lithium

calculation. 1. 3He and n abundances ? All reactions are too well-known. 3He is

indirectly measured by the solar neutrino flux. 2. 3He(, )7Be reaction is now known with better than 10%

accuracy.New nuclear ways of destroying 7Be ?

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Burning of 7Be using deuteriumIt has been suggested (Coc et al., 2004) that if the reaction rate of

7Be(d,p)®® is arbitrarily increased by a factor of ~ 100, the lithium problem can be “solved” right during the BBN.

Subsequent experimental search (Angulo et al., 2005) have shown no enhancement in this reaction.

It is important, however, that the search was made at E~400 keV, and the extrapolation to BBN regime was done assuming smoothness of astrophysical S-factor (cross section).

Such assumptions can be spectacularly violated by the presence of near threshold resonances ( e.g. F. Hoyle, 1950s).

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9B energy levels

from TUNL

nuclear data

project

Zooming in: 16.7 MeV resonance near 7Be +d

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Nothing much is known about 5/2+, 16.7 MeV +/- 100 keV resonance in 9B. Information about mirror nucleus, 9Be, shows that this resonance is extremely narrow.

We (R. Cyburt and MP) try to determine parameters of this resonance phenomenologically, and then see if it can be consistent with nuclear physics/quantum mechanics.

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Parameters of the resonance

Above the black line, 7Li/H < 0.5 [7Li/H]SBBN,and the Lithium problem is “solved”. One needs a resonance

in 160-200 keV range, and Gamma > 10 keV.

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Uncertainty in 7Li due to 9B resonance

¡ ~10 keV is a problem because of the Coulomb screening. Such a large deuterium separation width at a resonance energy of 200 keV implies extremely large radius for the 7Be+d interaction channel, as large as 10 fm. This is border-line of what is allowed by QM.

If indeed lithium problem is solved that way, it implies “new nuclear physics”, i.e. 16.7 MeV resonance in 9B is a 10 fm-size bound state of 7Li and Deuteron.

Being completely agnostic about properties of this resonance within QM, we arrive at the the following prediction for primordial lithium

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Enlarged error bars for 7Li

Experimental studies of the property of this resonance are required!

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Nonstandard BBN scenariosLate injection of electromagnetic/hadronic energy distorts primordial

abundances, especially for those elements where the SBBN processes are extremely inefficient

(4He(d,°)6Li is the radiative E2 reaction, suppressed by 8 orders of magnitude relative to “normal” reactions)

Energy injection with baryons in the final stay allows to circumvent this by a chain of endo-thermic but photonless reactions (Dimopoulos et al, 1980s) 4He + p 3H + p + p, Q=-16 MeV

There is a possibility of suppressing 7Be if O(10-5) neutrons per proton are injected (Jedamzik, 2004). This also increases D/H. Typical lifetime ~ 1000 sec is required.

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BBN with energy injectiondecaying dark matter

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BBN with energy injectionannihilating dark matter

Thermal WIMP

benchmark

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Catalyzed BBN Suppose that there is an electroweak scale remnant X (and X), e.g. SUSY partner of

electron, or , with the following properties:

1. Masses are in excess of 100 GeV to comply with LEP/Tevatron.

2. Abundances per baryon YX are O(0.10.001). In a fully specified model of particle physics they scale as YX » (0.010.05)mX/TeV.

3. Decay time X is longer than 1000 sec; no constraints on decay channels.

Are there changes in elemental abundances from mere presence of X? Yes! Anything at all that sticks to He with bindingenergy between 150 KeV and 1500 KeV will lead to the catalysis of 6Li production!Any quantities of (8BeX) in excess of 10-10 at 8 keV will lead to the

catalysis of 9Be to >10-13 level.

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Properties of bound states

fm7.1 KeV;3.8fm6.3;KeV350

KeV3972

He22

He

crecomb

b

Bohr

rTaE

mZE

fm5.2 KeV;35fm0.1;KeV1350

KeV27872

Be22

Be

crecomb

b

Bohr

rTaE

mZE

(4HeX) (7BeX)Bohr radius is 2 times larger than nuclear Bohr orbit is within nuclear radius

X

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Recombination of 4He and X

(4HeX) bottleneck

Naive equilibrium Saha-type equation

gives a rapid switch from 0 to 1 at 8.3 KeVRealistic solution to Boltzmann equation leads to a gradual increase of the

number of bound states. Catalyzed synthesis of 6Li will start below 9keV

)KeV3.8()/exp()2/(1

1)()(

2/3He

1He

-He TTETmnTn

Tn

bX

X

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After bound states have formed, new reaction channels open up

Main SBBN channel for 6Li production4He + D ! 6Li + ; Q = 1.47 MeV

in usual astrophysical units. 6Li(SBBN) » 10-14

NB: typical pre-exponents for reactions are 105106, for photon-less reactions 1081010

Main CBBN channel for 6Li production

(4HeX) + D ! 6Li + X; Q = 1.13 MeV

)/435.7exp(30 3/19

3/29 TTvSBBN

)/37.5exp(104.2 3/19

3/29

8 TTvCBBN

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New Reaction Channels

A possible SBBN channel for 9Be production8Be + n ! 9Be + ; Q = 1.66 MeV

9Be(SBBN) » 10-18

Main CBBN channel for 9Be production(8BeX) + n ! 9Be + X; Q = 0.26 MeV

This is a large photonless rate dominated by threshold resonance!

unstable is Beas collisons tripleRequires .0 8vSBBN

9100.2 vCBBN

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6Li and 9Be at 8 KeVCBBN with YX = 5£103, X=1 as a typical example,resulting in 6Li >10-8, and 9Be>10-11 – Excluded!

Observationally, 6Li/H < few£ 10-11; 9Be/H<few£ 10-13,

Therefore, YX(2£104sec) < 10-5 , and typically X < 5£ 103 s.

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6Li and 9Be at 8 KeVCBBN with YX = 101, X=2000s as a “just so” scenario

6Li/H=1.3£ 10-11; 9Be/H=7£ 10-14: A very intriguing pattern!!!9Be/6Li = (2-5)£ 10-3 - a typical “footprint” of CBBN

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Constraints on particle physics models

Type I: X! SM[X0], E » MX . Longevity because of small couplings. Examples:NLSP slepton (stau, smuon...) !Gravitino LSPNLSP slepton (stau, smuon...) ! "Dirac" RH sneutrino LSPLong-lived EW scale triplet Higgs decaying to SMType I requires taking care of "nonthermal" BBN effects.

Type II: X! X0 + e[]; E » few MeV or less.Longevity because of the small energy release. Examples:Closely degenerate stau-neutralino system Closely degenerate chargino-neutralino (O(MeV) splitting)Dark matter as heavy EW multiplet (O(MeV) splitting)Before CBBN, models of Type II were believed to be unconstrained by physics of

the Early Universe.

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Catalytic suppression of 7Be + 7Li

The “bottleneck” is creation of (7BeX) bound states that is controlled by 7Be+X! (7BeX) + reaction

There are two main destruction channels that are catalyzed: 1. p-reaction: (7BeX) + p ! (8BX) + by a factor of >1000 relative to 7Be + p ! 8B + 2. In models with weak current, the “capture” of X is catalyzed:

(7BeX) ! 7Li + X0 ,so that lifetime of (7BeX) becomes ¿ 1 sec. 7Li is significantly more

fragile and is destroyed by protons “on the spot”.3. There is significant energy injection via X +X ! (XX) ! radiation. If this process has hadronic modes, it

also affects Li7. 4. Combination of 6Li and 7Li constraints indicates the lifetime

1000-2000 s.

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How likely is such scenario? (SUSY landscape ? :)

Suppose nature chose the weak scale supersymmetry.There are two types of regular superpartners:Neutrals: neutralinos, sneutrinos. Charged: charged sleptons, squarks, charginosAll masses are at ~ TeV or less [one would hope!]“Probability” of mlightest charged < m

lightest neutral : 50%

Gravitino mass is a free parameter, not linked to weak scale“Probability” of mgravitino<mlightest charged < m

lightest neutral : 25%

In 25% cases SUSY models would have long-lived charged or strongly interacting relics!

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Conclusions 1. Lithium problem is a serious discrepancy between SBBN

prediction and Spite plateau value of 7Li abundance. Possibly indicates A. new delicate processes in the atmospheres of pop II stars, B. New nuclear physics channels (easy to check), C. New particles that catalyze 7Be destruction. Or the combination of the above. Last option is generally testable at LHC.

2. Energy injection via decay/annihilation of heavy relics is testable with BBN, especially in the channels that are accidentally suppressed in the standard scenario: 6Li, 9Be.

3. Catalysis of nuclear fusion is a new generic mechanism of how particle physics can affect the BBN predictions for lithium and beryllium. CBBN imposes important constraints on particle physics models that cannot be [yet] probed in other ways; this includes some TeV-scale SUSY models. 6Li and 9Be abundances are drastically enhanced, with ratio 6Li/9Be = (2-5) £ 10-3, affected by mere presence of charged particles during BNN. 7Li+7Be can be suppressed by a factor of ~ 2.