Cosmic string induced sheetlike baryon inhomogeneities at the quark-hadron transition

Layek, Biswanath; Sanyal, Sankar P.; Srivastava, Ajit M.

doi:10.1103/physrevd.63.083512

Cited by 24 publications

(35 citation statements)

References 29 publications

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“…Inhomogeneities can have planar, cylindrical or spherical symmetry [26,27,29,30,31]. The evolution of baryon inhomogeneous regions can be modelled using an IBBN code [6, 19, 20, [42].…”

Section: Introductionmentioning

confidence: 99%

Inhomogeneous big bang nucleosynthesis revisited

2006

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We reanalyze the allowed parameters for inhomogeneous big bang nucleosynthesis in light of the WMAP constraints on the baryon-to-photon ratio η and a recent measurement which has set the neutron lifetime to be 878.5 ± 0.7 ± 0.3 seconds. For a set baryon-to-photon ratio η the new lifetime reduces the mass fraction of 4 He by 0.0015 but does not significantly change the abundances of other isotopes. This enlarges the region of concordance between 4 He and deuterium in the parameter space of η and the IBBN distance scale r i . The 7 Li abundance can be brought into concordance with observed 4 He and deuterium abundances by using depletion factors as high as 9.3. The WMAP constraints, however, severely limit the allowed comoving (T = 100 GK) inhomogeneity distance scale to r i ≈ (1.3 − 2.6) × 10 5 cm. Big bang nucleosynthesis (BBN) plays a crucial role in constraining our views on the universe. It is essentially the only probe of physics in the early radiation dominated epoch during the interval from ∼ 1−10 4 sec. Moreover, big bang cosmology is currently undergoing rapid evolution based upon high precision determinations of cosmological parameters and improved input physics. Thus, it is important to scrutinize all possible variants of BBN and understand the constraints which modern observations place upon their parameters. This paper summarizes the current status on one such important variant of the big bang, namely one in which the baryons are spatially inhomogeneously distributed during the epoch of nucleosynthesis. We consider the constraints from WMAP and the latest observed elemental abundances and include recent measurements of thermonuclear reaction rates and the neutron lifetime. We show, that although the parameter space for inhomogeneous big bang nucleosynthesis (IBBN) is significantly limited, interesting regions remain and this paradigm continues to be a viable possibility for the early universe. II. BACKGROUNDAt a high temperature in the early universe, e.g. T ∼ 100 GK (the corresponding age of the universe is ∼ 0.01 seconds) baryons mainly exist in the form of free neutrons and protons.During this epoch neutrons and protons are rapidly interconverted via the following weak reactions [1,2,3] n + ν e ↔ p + e − n + e + ↔ p +ν e n ↔ p + e − +ν e .As long as these reactions are in thermal equilibrium the ratio of neutrons to protons is given by (n/p) = exp[−∆m/kT ] where ∆m is the mass difference between neutrons and protons. When the universe cools to a temperature T = 13 GK these weak reactions fall out of equilibrium. The n/p ratio after that time decreases only due to neutron decay.When the universe cools to a temperature T ≈ 0.9 GK the nuclear reaction n + p ↔ d + γ falls out of nuclear statistical equilibrium. Deuterium production becomes significant, 3 leading to the synthesis of increasingly heavier nuclei through a network of nuclear reactions and weak decays. When nearly all free neutrons are incorporated into 4 He nuclei, 4 He production virtually stops. The final mass fraction can be ap...

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“…Inhomogeneities can have planar, cylindrical or spherical symmetry [26,27,29,30,31]. The evolution of baryon inhomogeneous regions can be modelled using an IBBN code [6, 19, 20, [42].…”

Section: Introductionmentioning

confidence: 99%

Inhomogeneous big bang nucleosynthesis revisited

2006

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“…Generation of magnetic fields in cosmic string wakes Sovan Sau the temperature, an overdensity in the shock will mean a temperature gradient in the plasma [7]. This temperature gradient ∇ can be calculated at a particular temperature of the plasma.…”

Section: Pos(ichep2020)607mentioning

confidence: 99%

Generation of magnetic fields in cosmic string wakes

Sau¹,

Sanyal²

2021

Proceedings of 40th International Conference on High Energy Physics — PoS(ICHEP2020)

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We describe a novel method of generating magnetic fields in cosmic string wakes from neutrino currents. We show that neutrino currents act as a cross-perturbation across the cosmic string wake. This cross perturbation along with the high Reynolds number generates a magnetic field in the wake of the cosmic string. The neutrino current is generated by the neutrinos rotating around the Abelian Higgs strings. As the string moves through the cosmic plasma, the velocity kick generated by the motion of the string will enhance the neutrino current in the wake region. The neutrino current density depends on its distance from the string and is oscillatory in nature. This leads to neutrino density gradients in the plasma. We have shown that these neutrino gradients give rise to electron gradients in the plasma, which in turn generate magnetic fields of the order of 10 13 Gauss.

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“…This is because there is a greater probability of generating large over densities at the QCD scale [41]. Inhomogeneities can be generated by moving cosmic strings [25], collapsing Z(3) domain walls [42,43] and inhomogeneous nucleation of bubbles in a first order phase transition [44]. Inhomogeneities can be spread over an area of one meter and can have amplitudes of the order of 10 12 -10 13 through these various mechanisms.…”

Section: Baryon Inhomogeneities In the Early Universementioning

confidence: 99%

“…For the QCD epoch, we have the hadrons which carry the baryon number. Generally, the inhomogeneities which are generated at the QCD epoch have higher amplitude and sizes than those generated in the electroweak epoch [25]. Hence we consider these two cases separately.…”

Section: Introductionmentioning

confidence: 99%

Decay of baryon inhomogeneities in an expanding universe

Das

Saha

et al. 2021

Eur. Phys. J. C

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Baryon inhomogeneities are generated early in the universe. These inhomogeneities affect the phase transition dynamics of subsequent phase transitions, they also affect the nucleosynthesis calculations. We study the decay of the inhomogeneities in the early universe using the diffusion equation in the Friedmann–Lemaître–Robertson–Walker metric. We calculate the interaction cross section of the quarks with the neutrinos, the electrons and the muons and obtain the diffusion coefficients. The diffusion coefficients are temperature dependent. We find that the expansion of the universe causes the inhomogeneities to decay at a faster rate. We find that the baryon inhomogeneities generated at the electroweak epoch have low amplitudes at the time of the quark hadron transition and hence will not affect the phase transition dynamics unless they are generated with a amplitude greater than $$10^{5}$$ 10 5 times the background density. After the quark hadron transition, we include the interaction of the muons with the hadrons till 100 MeV. We find that large density inhomogeneities generated during the quark hadron transition with sizes of the order of 1 km must have amplitudes greater than $$10^{5} $$ 10 5 times the background density to survive upto the nucleosynthesis epoch. This puts constraints on any models that generate these inhomogeneities

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Cosmic string induced sheetlike baryon inhomogeneities at the quark-hadron transition

Cited by 24 publications

References 29 publications

Inhomogeneous big bang nucleosynthesis revisited

Inhomogeneous big bang nucleosynthesis revisited

Generation of magnetic fields in cosmic string wakes

Decay of baryon inhomogeneities in an expanding universe

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