Big bang nucleosynthesis and physics beyond the standard model

Sarkar, S.

doi:10.1088/0034-4885/59/12/001

Cited by 501 publications

(567 citation statements)

References 696 publications

(1,088 reference statements)

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“…Our D/H measurement implies a 4 He primordial mass fraction of Y p = 0.249 ± 0.001 ± 0.001 ± 0.001 (3,4), which is higher than recent values from extragalactic H II regions; Y p = 0.228 ± 0.005 (24) and Y p = 0.241 ± 0.003 (25). But it is now realized that systematic uncertainties might allow Y p = 0.25 (26,27).…”

contrasting

confidence: 68%

Cosmological baryon density derived from the deuterium abundance at redshift z = 3.57

Tytler

Fan

Burles

1996

Nature

305

281

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The primordial ratio of the number of deuterium to hydrogen nuclei (D/H) created in big bang nucleosynthesis is the most sensitive measure of the cosmological baryon to photon ratio and the cosmological density of baryons Ω b (1-5). In the interstellar medium (ISM) of our Galaxy D/H = 1.6 ± 0.1 × 10 −5 (6), which places a strict lower limit on the primordial abundance, because stars reduce the proportion of D in the ISM. Quasar absorption systems (QAS) should give definitive measurements of the primordial D because they can sample metal-poor gas at early epochs where the destruction of D should be negligible. A probable measurement of a high abundance ratio was reported in one QAS: D/H ≈ 24 × 10 −5 (7,8). Here we report a measurement of low D/H = 2.3 ×10 −5 , in another QAS, which is consistent with D/H in the ISM, with models of Galactic chemical evolution, (9,10), and with earlier data (7,8) provided that D line is strongly contaminated. We have internal consistency checks, and believe that this is the first direct measurement of a primordial abundance ratio. It provides the most accurate measurement of the baryon density: a high value of Ω b = 0.05, assuming a Hubble constant H 0 = 70 km s −1 Mpc −1 .Deuterium is rarely seen in QAS because the associated hydrogen is usually distributed over a wide range of velocities and its absorption covers deuterium. We selected QSO 1937-1009 because we found that the absorption system at z = 3.572 showed unusually weak metal lines in low resolution spectra, which we took to indicate that the gas was distributed in one or two narrow velocity components (11). We obtained optical spectra of QSO 1937-1009 (z em = 3.78, V ≃ 17.5) with the HIRES echelle spectrograph (12) on the W. M. Keck 10-m telescope. The high quality spectra make this amongst the best characterized QAS, and show strong absorption at the expected position of the D Lyα line and weak but highly significant absorption at D Lyβ .The weak metal lines in the system, C II, C IV, Si II, and Si IV, appear to have the same profiles, which are adequately described by two components separated by 15 km s −1 .

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contrasting

confidence: 68%

Cosmological baryon density derived from the deuterium abundance at redshift z = 3.57

Tytler

Fan

Burles

1996

Nature

305

281

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“…The radiation-domination constraint is weakly dependent on the brane tension above this value, implying that λ 1/4 > 10 6 GeV. Below the dot-dashed line, the temperature of the radiation at the end of inflation is less then 10 9 GeV, corresponding to the critical temperature where thermal gravitino production may be problematic [24]. This constraint is satisfied for all n < 50.…”

Section: /3mentioning

confidence: 93%

Inflation, braneworlds and quintessence

2001

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Inflationary cosmology is developed in the second Randall-Sundrum braneworld scenario, where the accelerated expansion arises through potentials that are too steep to drive inflation in conventional cosmology. A relationship between the scalar and tensor perturbation spectra is derived that is independent of both the inflaton potential and the brane tension. It is found that a single field with an inverse power law potential can act as both the inflaton and the quintessence field for suitable values of the brane tension.

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“…(16) does not exceed 10 9 GeV, the temperature at which thermal production of gravitinos might be significant [20]. It can be checked from Eq.…”

Section: Constraints From Radiation and Matter Dominated Erasmentioning

confidence: 89%

“…Eq. (20) can be used to check the consistency of the constraint (19) at different stages, for example, at t nuc when the recently obtained bound (Ω φ ) nuc < 0.045 [22] needs to be satisfied. The existence of tracking behaviour can be determined by the quantity [13] …”

Section: Constraints From Radiation and Matter Dominated Erasmentioning

confidence: 99%

From brane assisted inflation to quintessence through a single scalar field

Majumdar

2001

Phys. Rev. D

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We explore within the context of brane cosmology whether it is possible to obtain both early inflation and accelerated expansion during the present epoch through the dynamics of the same scalar field in an exponential potential. Considerations from successful inflation and viable radiation and matter dominated eras impose constraints on the parameters of the potential. We find that the additional requirement of late time quintessence behaviour in conformity with present observations necessitates the inclusion of two exponential terms in the potential. PACS number(s): 98.80.Cq

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Big bang nucleosynthesis and physics beyond the standard model

Cited by 501 publications

References 696 publications

Cosmological baryon density derived from the deuterium abundance at redshift z = 3.57

Cosmological baryon density derived from the deuterium abundance at redshift z = 3.57

Inflation, braneworlds and quintessence

From brane assisted inflation to quintessence through a single scalar field

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