• The Universe is expanding
• The Universe is filled with radiation
• The Early Universe was Hot & Dense
 The Early Universe was a
Cosmic Nuclear Reactor!
~ 100 s after the Big Bang
Primordial Nucleosynthesis
~ 1 - 10 Gyr LSS
~ 0.1 s after the Big Bang
Neutrinos Decouple
~ 400 kyr after the Big Bang
Relic Photons (CMB) are free
Neutron Abundance vs. Time / Temperature
p + e  n +  e …
Rates set by n
“Freeze – Out” ? Wrong!
(n/p)eq
BBN “Begins”
 Decay
 n measurements vs. time
Statistical Errors
versus
Systematic Errors !
885.7  0.8 sec
BBN “Begins” at T  70 keV
when n / p  1 / 7
Coulomb Barriers and absence of free
neutrons terminate BBN at T  30 keV
tBBN  4  24 min.
Pre - BBN
Only n & p
Post - BBN
Mainly H & 4He
Baryon Density Parameter
  nN / n ; 10   
= 274
Bh2
where : B  B / c
and : h  H0 / 100 km / s / Mpc  0.7
Note : Baryons  Nucleons
Evolution of mass - 2
10
More nucleons

less D
Two pathways to mass - 3
More nucleons

less mass - 3
Two pathways to mass - 7
BBN abundances of masses – 6, 9 – 11
Abundances Are Very Small !
BBN – Predicted Primordial Abundances
BBN Abundances of D, 3He, 7Li
are RATE (Density) LIMITED
7Li
7Be
D, 3He, 7Li are potential BARYOMETERS
Use BBN ( D / H ) P vs. 10 to constrain B
Predict (D/H)P
“Measure” ( D / H ) P
Infer B (B) at 20 Min.
Y is very weakly dependent on the nucleon abundance
All / most neutrons are incorporated in 4He
n/p  1/7

Y
 0.25
Y  4He Mass Fraction
Y  4y/(1 + 4y)
y  n(He)/n(H)
YP DOES depend on the competition between Γwk & H
• 4He (mass fraction Y) is NOT Rate Limited
• 4He IS n/p Limited  Y is sensitive to the
EXPANSION RATE ( H  1/2 )
• Expansion Rate Parameter : S  H´/ H
S  H´/ H  (´ / )1/2  (1 + 7N / 43)1/2
where ´   + N  and N  3 + N
The Expansion Rate (H  Hubble Parameter)
Is A Probe Of Non-Standard Physics
•
S2  (H/ H)2 = G/ G   1 + 7N / 43
* S can be parameterized by N
N  ( - ) /  and N  3 + N
NOTE : G/ G = S2  1 + 7N / 43
• 4He is sensitive to S (N) ; D probes B
4He
is an early – Universe Chronometer
Y vs. D / H
N = 2, 3, 4
(S = 0.91, 1.00, 1.08)
Y  0.013 N  0.16 (S – 1)
Isoabundance Contours for 105(D/H)P & YP
YP & yD  105 (D/H)
4.0
2.0
3.0
0.25
0.24
0.23
D & 4He Isoabundance Contours
Kneller & Steigman (2004)
Kneller & Steigman (2004) & Steigman (2007)
yDP  105(D/H)P = 46.5 (1 ± 0.03) D-1.6
YP = (0.2386 ± 0.0006) + He / 625
y7  1010(7Li/H) = (1.0 ± 0.1) (LI)2 / 8.5
where :
D  10 –
6 (S – 1)
He  10 –
100 (S – 1)
Li  10 –
3 (S – 1)
Post – BBN Evolution
• As gas cycles through stars, D is only DESTROYED
• As gas cycles through stars, 3He is DESTROYED ,
PRODUCED and, some 3He SURVIVES
• Stars burn H to 4He (and produce heavy elements)

4He
INCREASES (along with CNO)
• Cosmic Rays and SOME Stars PRODUCE 7Li BUT,
7Li
is DESTROYED in most stars
Observing D in QSOALS
Ly -  Absorption
Towards Primordial Deuterium
Observations of Deuterium In
7 High-Redshift, Low-Metallicity
QSO Absorption Line Systems
105(D/H)P = 2.7 ± 0.2
(Weighted Mean of D/H)
(Weighted mean of log (D/H)
 105(D/H)P = 2.8 ± 0.2)
(D /H)obs + BBNpred
 10 =
6.0 ± 0.3
BBN
V. Simha & G. S.
CMB Temperature Anisotropy Spectrum
(T2 vs. ) Depends On The Baryon Density
 
10 =
4.5, 6.1, 7.5
V. Simha & G. S.
The CMB provides an early - Universe Baryometer
CMB + LSS
 10
10
= 6.1 ± 0.2
Likelihood
CMB
V. Simha & G. S.
Primordial Deuterium Predicted
BBN + CMB/LSS

105(D/H)P = 2.6 ± 0.1
BBN (~ 20 min) & CMB (~ 380 kyr) AGREE
10
Likelihoods
CMB
BBN
V. Simha & G. S.
Oxygen Gradient In The Galaxy
3He
Measured In Galactic HII Regions
SBBN
3He
Measured In Galactic HII Regions
SBBN
4He
Observed In Extragalactic H  Regions
As O/H  0, Y  0
SBBN Prediction : YP = 0.248
K. Olive
YP = 0.240 ± 0.006 ( Or : YP < 0.255 @ 2 σ )
SBBN
10 Likelihoods from D and 4He
AGREE ?
to be continued …
But ! Lithium – 7 Is (ALSO) A Problem
[Li] ≡ 12 + log(Li/H)
[Li]SBBN
 2.6 – 2.7
[Li]OBS
 2.1
Li too low !
Baryon Density Determinations: Consistent ?
Late - Decaying NLSP ?
?
N < 3 ?
Observational Uncertainties Or New Physics?
YP vs. (D/H)P for N = 2, 3, 4
N  3 ?
A Non-Standard BBN Example (Neff < 3)
Late Decay of a
Massive Particle
Kawasaki, Kohri & Sugiyama
&
Low Reheat Temp.
(TR  MeV)

Relic Neutrinos Not
Fully (Re) Populated
Neff < 3
Isoabundance Contours for 105(D/H)P & YP
YP & yD  105 (D/H)
4.0
3.0
2.0
0.25
0.24
0.23
Kneller & Steigman (2004)
N vs. 10 From BBN (D & 4He)
( YP < 0.255 @ 2 σ )
BBN Constrains N
N < 4
N > 1
V. Simha & G. S.
CMB Temperature Anisotropy Spectrum
Depends on the Radiation Density R (S or N)
 
N = 1, 3, 5
V. Simha & G. S.
The CMB / LSS is an early - Universe Chronometer
N Is Degenerate With mh2
The degeneracy can be broken
- partially - by H0 (HST) and LSS
1 + zeq = m / R
1 + zeq ≈ 3200
V. Simha & G. S.
CMB + LSS + HST Prior on H0
N vs. 10
CMB + LSS Constrain 10
V. Simha & G. S.
Use the CMB + LSS to bound η10 and N
Use BBN to predict YP , yDP , yLiP (solid black)
Compare to the observed abundances (dashed)
4He
Korn et al. 7Li
D


?
V. Simha & G. S.
Even for N  3
Y + D  H  Li  H  4.0  0.7 x 10 10
yLi  1010 (Li/H)
4.0
3.0
2.0
0.25
4.0
0.24
0.23
Li depleted / diluted
in Pop  stars ?
Kneller & Steigman (2004)
Alternative to N  3 (S  1)
e
Degeneracy (Non – Zero Lepton Number)
YP & yD
For e = e/kT  0
(more e than anti - e)
4.0

105 (D/H)
3.0
2.0
0.23
n/p  exp ( m/kT  e )
0.24
 n/p   YP 
0.25
YP probes
D & 4He Isoabundance Contours
Lepton Asymmetry
Kneller & Steigman (2004)
Kneller & Steigman (2004) & Steigman (2007)
yDP  105(D/H)P = 46.5 (1 ± 0.03) D-1.6
YP = (0.2386 ± 0.0006) + He / 625
y7  1010(7Li/H) = (1.0 ± 0.1) (LI)2 / 8.5
where :
D  10 + 5 e / 4
He  10 – 574 e / 4
Li  10 –
7 e / 4
e
Degeneracy (Non – Zero Lepton Number)
YP & yD  105 (D/H)
For N = 3 :
e =
2.0
3.0
0.23
0.035  0.026
&
10
4.0
= 5.9  0.4 
(V. Simha & G. S.)
0.24
0.25
BBN Constraints (D & 4He) On e For N = 3
e = 0.035 ± 0.026
10 = 5.9 ± 0.3
V. Simha & G.S.
Even With Non - Zero e Degeneracy,
The 7Li Problem Persists
yLi  1010 (7Li/H)
[Li] = 2.6  0.7 Still !
4.0
[Li] = 2.7  0.7 with
CFO 2008 results
Li depleted / diluted
in Pop  stars ?
Or, Late Decay of
(Charged) NLSP ?
4.0
2.0
3.0
0.23
0.24
0.25
BBN & The CBR Provide Complementary
Probes Of The Early Universe
Do predictions and observations of the
baryon density parameter (B) and the
expansion rate parameter (S or N) agree
at 20 minutes and at 400 kyr ?
BBN (D & 4He) & CMB + LSS + HST AGREE !
N vs. 10
CMB + LSS
BBN
V. Simha & G. S.
Several consequences of the good
agreement between BBN and CMB + LSS
Entropy Conservation : N (CMB) / N (BBN) = 0.92 ± 0.07
Modified Radiation Density (late decay of massive particle)
ρRCMB / ρRBBN = 1.07 +0.16 -0.13
Variation in the Gravitational Constant ?
GBBN / G0 = 0.91 ± 0.07 ; GCMB / G0 = 0.99 ± 0.12
BBN + CMB + LSS Combined Fit
N vs. 10
( YP < 0.255 @ 2 σ )
N = 2.5 ± 0.4
10 = 6.1 ± 0.1
V. Simha & G.S.
N & e BOTH FREE, BBN + CMB/LSS
Consistent with e = 0 & N = 3
N = 3.3 ± 0.7
e =
0.056 ± 0.046
V. Simha & G.S.
CONCLUSIONS
BBN (D, 3He, 4He) Agrees With
The CMB + LSS (For N ≈ 3 & e ≈ 0)
(But, 7Li is a problem)
BBN + CMB + LSS Combined Can Constrain
Non-Standard Cosmology & Particle Physics