scholarly journals Aspects of brane-antibrane inflation

2006 ◽  
Vol 84 (6-7) ◽  
pp. 447-452 ◽  
Author(s):  
James M Cline
Keyword(s):  
Cosmic Microwave Background ◽  
Spectral Index ◽  
Fine Tuning ◽  
Good Chance ◽  
Microwave Background ◽  
Dynamical Mechanism ◽  
98.80 Cq

I describe a dynamical mechanism for solving the fine-tuning problem of brane-antibrane inflation. By inflating with stacks of branes and antibranes, the branes can naturally be trapped at a metastable minimum of the potential. As branes tunnel out of this minimum, the shape of the potential changes to make the minimum shallower. Eventually the minimum disappears and the remaining branes roll slowly because the potential is nearly flat. I show that even with a small number of branes, there is a good chance of getting enough inflation. Running of the spectral index is correlated with the tilt in such a way as to provide a test of the model by future cosmic microwave background experiments.PACS Nos.: 11.25.Wx, 98.80.Cq

scholarly journals Cosmological birefringence induced by neutrino current

2008 ◽  
Vol 86 (4) ◽  
pp. 587-590 ◽  
Author(s):  
C Q Geng ◽  
S H Ho ◽  
J N Ng
Keyword(s):  
Cosmic Microwave Background ◽  
Recent Work ◽  
Background Radiation ◽  
Polarization Angle ◽  
Microwave Background ◽  
Effective Interactions ◽  
Microwave Background Radiation ◽  
98.80 Cq ◽  
New Type ◽  
Chern Simons

We review our recent work, Geng et al. (J. Cosmol. Astropart. Phys. 09, 010 (2007)) on the cosmological birefringence. We propose a new type of effective interactions in terms of the CPT-even dimension-six Chern–Simons-like term to generate the cosmological birefringence. We use the neutrino number asymmetry to induce a nonzero rotation polarization angle in the data of the cosmic microwave background-radiation polarization.PACS Nos.: 98.80.Cq, 98.80.Es, 11.30.Fs

scholarly journals Imprints of the post-recombination dissipation of helical magnetic field on the Cosmic Microwave Background Radiation

2020 ◽  
pp. 2050122
Author(s):  
Sandhya Jagannathan ◽  
Ramkishor Sharma ◽  
T. R. Seshadri
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Cosmic Microwave Background ◽  
Spectral Index ◽  
Background Radiation ◽  
Power Spectra ◽  
Ambipolar Diffusion ◽  
Microwave Background ◽  
The Impact ◽  
The Magnetic Field

Astrophysical magnetic fields decay primarily via two processes, namely ambipolar diffusion and turbulence. Constraints on the strength and the spectral index of nonhelical magnetic fields have been derived earlier in the literature through the effect of the above-mentioned processes on the cosmic microwave background (CMB) radiation. A helical component of the magnetic field is also produced in various models of magnetogenesis, which can explain larger coherence length magnetic field. In this study, we focus on studying the effects of post-recombination decay of maximally helical magnetic fields through ambipolar diffusion and decaying magnetic turbulence and the impact of this decay on CMB. We find that helical magnetic fields lead to changes in the evolution of baryon temperature and ionization fraction which in turn lead to modifications in the CMB temperature and polarization anisotropy. These modifications are different from those arising due to nonhelical magnetic fields with the changes dependent on the strength and the spectral index of the magnetic field power spectra.

scholarly journals Some remarks on nonminimal coupling of the inflaton

2014 ◽  
Vol 23 (09) ◽  
pp. 1450076 ◽  
Author(s):  
Namit Mahajan
Keyword(s):  
Quantum Theory ◽  
Power Spectrum ◽  
Cosmic Microwave Background ◽  
Spectral Index ◽  
Einstein Frame ◽  
Conformal Transformations ◽  
Matrix Elements ◽  
Nonminimal Coupling ◽  
Microwave Background ◽  
Quartic Coupling

The nonminimal coupling of the inflaton is known to alleviate the smallness of the quartic coupling λ in the chaotic inflation with ϕ4 potential. A large ξ is required to obtain the cosmic microwave background (CMB) power spectrum while a small value ~ 1/6 seems to be preferred from spectral index. There are issues related to conformal transformations, choice of frame and natural value(s) of ξ for a given potential. We revisit some of these issues and invoke field theoretic arguments (which exist in different context and have not been employed previously in the context of inflation) in order to address the same. A rather strong and general conclusion reached, based on the requirements of renormalizability and finiteness of specific matrix elements in a quantum theory, is that it is generically not possible to eliminate the nonminimal coupling by going from the Jordan to the Einstein frame via conformal transformations. We also comment on Higgs inflation.

Small‐Scale Cosmic Microwave Background Observations at 8.4 GHz

1997 ◽  
Vol 483 (1) ◽  
pp. 38-50 ◽  
Author(s):  
R. Bruce Partridge ◽  
Eric A. Richards ◽  
Edward B. Fomalont ◽  
K. I. Kellerman ◽  
Rogier A. Windhorst
Keyword(s):  
Cosmic Microwave Background ◽  
Small Scale ◽  
Microwave Background

scholarly journals The evolution of the cosmic microwave background temperature

2011 ◽  
Vol 526 ◽  
pp. L7 ◽  
Author(s):  
P. Noterdaeme ◽  
P. Petitjean ◽  
R. Srianand ◽  
C. Ledoux ◽  
S. López
Keyword(s):  
Cosmic Microwave Background ◽  
Microwave Background ◽  
Cosmic Microwave Background Temperature ◽  
Background Temperature

scholarly journals Revisiting cosmic microwave background radiation using blackbody radiation inversion

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Koustav Konar ◽  
Kingshuk Bose ◽  
R. K. Paul
Keyword(s):  
Temperature Distribution ◽  
Cosmic Microwave Background ◽  
Background Radiation ◽  
Big Bang ◽  
Blackbody Radiation ◽  
Microwave Background ◽  
Background Spectrum ◽  
Microwave Background Radiation ◽  
Mathematical Process

AbstractBlackbody radiation inversion is a mathematical process for the determination of probability distribution of temperature from measured radiated power spectrum. In this paper a simple and stable blackbody radiation inversion is achieved by using an analytical function with three determinable parameters for temperature distribution. This inversion technique is used to invert the blackbody radiation field of the cosmic microwave background, the remnant radiation of the hot big bang, to infer the temperature distribution of the generating medium. The salient features of this distribution are investigated and analysis of this distribution predicts the presence of distortion in the cosmic microwave background spectrum.

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