Big-Bang Nucleosynthesis

TLDR: In this article, a critical review of the current status of cosmological nucleosynthesis is given, where the baryon-to-photon ratio of deuterium and helium-4 is consistent with the independent determination of $\eta$ from observations of anisotropies in the cosmic microwave background.

Abstract: A critical review is given of the current status of cosmological nucleosynthesis. In the framework of the Standard Model with 3 types of relativistic neutrinos, the baryon-to-photon ratio, $\eta$, corresponding to the inferred primordial abundances of deuterium and helium-4 is consistent with the independent determination of $\eta$ from observations of anisotropies in the cosmic microwave background. However the primordial abundance of lithium-7 inferred from observations is significantly below its expected value. Taking systematic uncertainties in the abundance estimates into account, there is overall concordance in the range $\eta = (5.7-6.7)\times 10^{-10}$ at 95% CL (corresponding to a cosmological baryon density $\Omega_B h^2 = 0.021 - 0.025$). The D and He-4 abundances, when combined with the CMB determination of $\eta$, provide the bound $N_\nu=3.28 \pm 0.28$ on the effective number of neutrino species. Other constraints on new physics are discussed briefly.

Figures

Figure 33.8: Charge rate dependence of normalized gas gain G/G0 (relative to zero counting rate) in proportional thin-wire detectors [80]. Q is the total charge in single avalanche; N is the particle rate per wire length.

Table 11.11: Correspondence between the κ’s and the Wilson coefficients of the dimension-6 operators of the Higgs EFT Lagrangian constrained only by Higgs physics.

Figure 11.17: Likelihood contours for individual production mode signal strengths (ggF + ttH versus V BF +V H) for various decay modes for the ATLAS experiment A1 [119] and the CMS experiment C1 [120] results.

Table 42.1: Meson numbering logic. Here qq stands for nq2 nq3.

Figure 13.1: Graphical representation of the unitarity constraint VudV ∗ ub + VcdV ∗ cb + VtdV ∗ tb = 0 as a triangle in the complex plane.

Table 37.1 gives a number of common probability density functions and corresponding characteristic functions, means, and variances. Further information may be found in Refs. [1– 8], [10], and [11], which has particularly detailed tables. Monte Carlo techniques for generating each of them may be found in our Sec. 39.4 and in Ref. [10]. We comment below on all except the trivial uniform distribution.

Frequently asked questions

Q1. What is the only technique that addresses all sources of neutron background?

Moving the detector deepunderground, and thus reducing the muon flux, is the only technique addressing all sources of neutron background. 

Q2. What can be used to combine a number of classifiers into a stronger one?

Techniques such as “boosting” and “bagging” can be applied to combine a number of classifiers into a stronger one with greater stability with respect to fluctuations in the training data. 

Q3. What are the contributions in this paper?

In this paper, the authors proposed a dynamical electroweak symmetry breaking model, in which the femtors of the massive weak bosons are identified with composite Nambu-Goldstone bosons arising from dynamical symmetry breaking in a strongly-coupled extension of the standard model. 

Q4. What is the accurate and efficient choice for assessing radiation protection quantities at accelerators?

The use of general-purpose particle interaction and transport Monte Carlo codes is often the most accurate and efficient choice for assessing radiation protection quantities at accelerators. 

Q5. What is the probable charge deposition in a 300 m thick silicon detector?

For minimum-ionizing particles, the most probable charge deposition in a 300 µm thick silicon detector is about 3.5 fC (22000 electrons). 

Q6. How much of the E is transferred to the final state lepton in neutrino reactions?

On average, between 50% (65%) and 75% of Eν is transfered to the final-state lepton in neutrino (antineutrino) reactions between 100 GeV and 10 PeV. 

Q7. What is the way to mitigate the problem of excluding models to which one is not sensitive?

One way to mitigate the problem of excluding models to which one is not sensitive is the CLs method, where the measure used to test a parameter is increased for decreasing sensitivity [34,35]. 

Q8. Why is the energy sum of the final state of a B meson decay equal to half?

Because of the kine-matic constraint of Υ(4S), the energy sum of the final-stateparticles of a B meson decay is always equal to one half of thetotal energy in the center of mass frame. 

Q9. Why is a new appreciation for the significance of nuclear effects surfaced in pion production channels?

As with QE scattering, a new appreciation for the significance of nuclear effects has surfaced in pion production channels, again due to the use of heavy nuclear targets in modern neutrino experiments. 

Q10. What techniques have been applied to neutralize the damage sites?

Since the effect of radiation damage depends on the electronic activity of defects, various techniques have been applied to neutralize the damage sites. 

Q11. How many jets are reconstructed in the detectors?

The number of jets reconstructed in the detectors dependson the decay kinematics, as well as on the algorithm forreconstructing jets used by the analysis. 

Q12. Why is water the preferred medium for large detectors?

because water can be obtained relatively cheaply in large amounts, it has become the medium of choice for most large detectors. 

Q13. How much is the drift velocity of ions in the fields encountered in gaseous detectors?

The drift velocity of ions in the fields encountered in gaseous detectors (up to few kV/cm) is typically about three orders of magnitude less than for electrons. 

Q14. How many times can the angular resolution be dominated by the muon reconstruction accuracy?

For CC ֒ ֓νµ reactions at energies above a few TeV, the angular resolution is dominated by the muon reconstruction accuracy of a few times 0.1◦ at most. 

Q15. what is the angular distribution of decay products?

The angular distribution of decay products can be expressed asa function of three helicity angles which describe the alignmentof the particles in the decay chain. 

Q16. What are the two main ways that neutrons contribute to the background of low energy experiments?

Neutrons : Neutrons contribute to the background of lowenergy experiments in different ways: directly through nuclear recoil in the detector medium, and indirectly, through the production of radio nuclides inside the detector and its components. 

Q17. What is the mechanism that allows even remote materials to contribute to the background?

The latter mechanism allows even remote materials to contribute to the background by means of penetrating γ radiation, since inelastic scattering of fast neutrons or radiative capture of slow neutrons can result in the emission of γ radiation. 

Q18. What is the main approach to controlling discretization errors in lattice studies of heavy?

the main approach to controlling the dis-cretization errors in lattice studies of heavy quark physics is toperform simulations of the effective theories such as HQET andNRQCD. 

Q19. Why are there theories in which the W ′ and Z ′ masses are negligible?

however, theories in which these mixings are negligible (e.g.due to a new parity [4]), even when the W ′ and Z ′ masses arebelow the electroweak scale. 

Q20. What are the priors that are invariant under a transformation of parameters?

These give, for example, priors which are invariant under a transformation of parameters, or ones which result in a maximum gain in information for a given set of measurements. 

Q21. How can the spin correlation be modified?

The spin correlation could be modified bya new tt̄ production mechanism such as through a Z ′ boson,Kaluza-Klein gluons, or a Higgs boson.