Javier Redondo
The existence and cosmological signatures of a relic background of very weakly interacting sub-eV particles (WISPs), produced by photon-WISP oscillations is reviewed.
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We present several new ideas on how to search for weakly interacting sub-eV particles in laboratory experiments. The first experiment is sensitive to minicharged particles. It exploits that in strong electric fields particle - antiparticle pairs are produced by the Schwinger mechanism. The charged particles move along the lines of the electric field and generate a current that can be measured. The other two experiments are designed to search for hidden-sector photons. They are based on photon - hidden photon oscillations and resemble classic light shining through a wall experiments. One uses (…
Cross-correlation measurement techniques for cavity-based axion and weakly interacting slim particle searches
针对暗物质候选者 WISPs 探测中多微波腔功率合成的技术难题，提出一种基于互相关的测量方案，有效合成多个腔的功率并提升候选 WISP 信号的信噪比。
We investigate the possibilities of constraining the light gravitino mass m_{3/2} from future cosmic microwave background (CMB) surveys. A model with light gravitino with the mass m_{3/2}<O(10) eV is of great interest since it is free from the cosmological gravitino problem and, in addition, can be compatible with many baryogenesis/leptogenesis scenarios such as the thermal leptogenesis. We show that the lensing of CMB anisotropies can be a good probe for m_{3/2} and obtain an expected constraint on m_{3/2} from precise measurements of lensing potential in the future CMB surveys, such as the P…
An improved estimator for the amplitude fnl of local-type non-Gaussianity from the cosmic microwave background (CMB) bispectrum is discussed. The standard estimator is constructed to be optimal in the zero-signal (i.e., Gaussian) limit. When applied to CMB maps which have a detectable level of non-Gaussianity the standard estimator is no longer optimal, possibly limiting the sensitivity of future observations to a non-Gaussian signal. Previous studies have proposed an improved estimator by using a realization-dependent normalization. Under the approximations of a flat sky and a vanishingly thi…
Primordial magnetic fields will generate non-Gaussian signals in the cosmic microwave background (CMB) as magnetic stresses and the temperature anisotropy they induce depend quadratically on the magnetic field. We compute a new measure of magnetic non-Gaussianity, the CMB trispectrum, on large angular scales, sourced via the Sachs-Wolfe effect. The trispectra induced by magnetic energy density and by magnetic scalar anisotropic stress are found to have typical magnitudes of approximately a few times 10^{-29} and 10^{-19}, respectively. Observational limits on CMB non-Gaussianity from WMAP data…
We present a significant update of the constraints on the Abelian Higgs cosmic string tension by cosmic microwave background (CMB) data, enabled both by the use of new high-resolution CMB data from suborbital experiments as well as the latest results of the WMAP satellite, and by improved predictions for the impact of Abelian Higgs cosmic strings on the CMB power spectra. The new cosmic string spectra (presented in a previous work) were improved especially for small angular scales, through the use of larger Abelian Higgs string simulations and careful extrapolation. If Abelian Higgs strings ar…
In this talk, I review some recent work on cosmic microwave background (CMB) anisotropies in an open universe. I emphasize that the observed CMB anisotropies are still consistent with a low value of $Ω$, and I address the question of whether future CMB measurements will be able to provide information on the geometry of the Universe.
Quantum fluctuations during inflation may be responsible for temperature anisotropies in the cosmic microwave background (CMB). Observations of CMB anisotropies can be used to falsify many currently popular models. In this paper we discuss the prospectus for observations of CMB anisotropies at the accuracy of planned satellite missions to reject currently popular inflation models and to provide some direction for model building.
The Einstein Equivalence Principle~(EEP) can be verified by the measurement of the spectral distortions of the Cosmic Microwave Background (CMB). The existence of energy-dependency in the cosmological redshift effect means the EEP violation. Introducing the energy-dependent Friedmann-Robertson-Walker metric motivated by rainbow gravity, we show that the energy-dependent redshift effect causes the CMB spectral distortions. Assuming the simple energy-dependent form of the metric, we evaluate the distortions. From the COBE/FIRAS bound, we find that the deviation degree from the EEP, which is comp…
We review in a pedagogical way the present status of the impact of non-Gaussianity (NG) on the Cosmic Microwave Background (CMB) anisotropies. We first show how to set the initial conditions at second-order for the (gauge invariant) CMB anisotropies when some primordial NG is present. However, there are many sources of NG in CMB anisotropies, beyond the primordial one, which can contaminate the primordial signal. We mainly focus on the NG generated from the post-inflationary evolution of the CMB anisotropies at second-order in perturbation theory at large and small angular scales, such as the …
Millimeter-wave WISP search with coherent Light-Shining-Through-a-Wall towards the STAX project
本文提出利用相干毫米波在光穿墙实验中搜索质量约10^-4至10^-3 eV的暗光子，阐明相干探测优缺点并探讨单光子传感器，为毫米波轴子STAX实验奠定基础。
In forthcoming years, connections between cosmology and particle physics will be made increasingly important with the advent of a new generation of cosmic microwave background (CMB) experiments. Here, we review a number of these links. Our primary focus is on new CMB tests of inflation. We explain how the inflationary predictions for the geometry of the Universe and primordial density perturbations will be tested by CMB temperature fluctuations, and how the gravitational waves predicted by inflation can be pursued with the CMB polarization. The CMB signatures of topological defects and primord…
When a subdominant light scalar field ends slow roll during inflation, but well after the Hubble exit of the pivot scales, it may determine the cosmological perturbations. This thesis investigates how such a scalar field, the spectator, may leave its impact on the Cosmic Microwave Background (CMB) radiation and be consequently constrained. We first introduce the observables of the CMB, namely the power spectrum $P_ζ$, spectral index $n_s$ and its running $dn_s/d\ln k$, the non-Gaussianities $f_{NL}$, $g_{NL}$ and $τ_{NL}$, and the lack of isocurvature and polarization modes. Based on these stu…
We study the Cosmic Microwave Background (CMB) anisotropies produced by cosine-type quintessence models. In our analysis, effects of the adiabatic and isocurvature fluctuations are both taken into account. For purely adiabatic fluctuations with scale invariant spectrum, we obtain a stringent constraint on the model parameters using the CMB data from COBE, BOOMERanG and MAXIMA. Furthermore, it is shown that isocurvature fluctuations have significant effects on the CMB angular power spectrum at low multipoles in some parameter space, which may be detectable in future satellite experiments. Such …
We discuss effects of cosmological moduli fields on the cosmic microwave background (CMB). If a modulus field ϕonce dominates the universe, the CMB we observe today is from the decay of ϕand its anisotropy is affected by the primordial fluctuation in the amplitude of the modulus field. As a result, constraints on the inflaton potential from the CMB anisotropy can be relaxed. In addition, with the cosmological moduli fields, correlated mixture of adiabatic and isocurvature fluctuations may be generated, which results in enhanced CMB angular power spectrum at higher multipoles relative to that o…
A time variation in the Higgs vacuum expectation value alters the electron mass and thereby changes the ionization history of the universe. This change produces a measurable imprint on the pattern of cosmic microwave background (CMB) fluctuations. The nuclear masses and nuclear binding energies, as well as the Fermi coupling constant, are also altered, with negligible impact on the CMB. We calculate the changes in the spectrum of the CMB fluctuations as a function of the change in the electron mass. We find that future CMB experiments could be sensitive to |Δm_e/m_e| \sim |ΔG_F/G_F| \sim 10^{-…
One of the major predictions of inflation is the existence of a stochastic background of cosmological gravitational waves (GW). These gravitational waves can induce significant temperature anisotropies in the Cosmic Microwave Background (CMB) on the angular scales recently probed by the Archeops experiment. Here, we perform a combined analysis of Archeops together with information from other CMB experiments and/or cosmological datasets, in order to constrain the amplitude of the GW background. We find that, for a scale-invariant GW background, the ratio of tensor/scalar perturbations at the CM…
We calculate the large scale polarization of the cosmic microwave background induced by the anisotropy of the spatial geometry of our universe. Assuming an eccentricity at decoupling of about $0.64 10^{-2}$, we find $ΔT_{pol}/ T_0 \simeq 0.53 10^{-6}$ quite close to the average level of polarization detected by the Wilkinson Microwave Anisotropy Probe.
We discuss effects of cosmological moduli fields on the cosmic microwave background (CMB). If a modulus field ϕonce dominates the universe, the CMB we observe today is from the decay of ϕand its anisotropy is affected by the primordial fluctuation in the amplitude of the modulus field. Consequently, constraints on the inflaton potential from the CMB anisotropy can be relaxed. In particular, the scale of the inflation may be significantly lowered. In addition, with the cosmological moduli fields, correlated mixture of adiabatic and isocurvature fluctuations may be generated, which results in en…
The primordial anisotropies of the cosmic microwave background (CMB) are linearly polarized via Compton-scattering. The Faraday conversion process during the propagation of polarized CMB photons through regions of the large-scale structure containing magnetized relativistic plasma, such as galaxy clusters, will lead to a circularly polarized contribution. Though the resulting Stokes-V parameter is of order 10^-9 at frequencies of 10 GHz, the contribution can potentially reach the total Stokes-U at low frequencies due to the cubic dependence on the wavelength. In future, the detection of circul…
Much recent work on the cosmic microwave background (CMB) has focussed on the angular power spectrum of temperature anisotropies and particularly on the recovery of cosmological parameters from acoustic peaks in the power spectrum. However, there is more that can conceivably be done with CMB measurements. Here I briefly survey a few such ideas: cross-correlation with other cosmic backgrounds as a probe of the density of the Universe; CMB polarization as a gravitational-wave detector; secondary anisotropies and the ionization history of the Universe; tests of alternative-gravity theories; polar…
The COBE satellite has discovered anisotropies in the cosmic microwave background (CMB) consistent with a scale invariant spectrum of density perturbations. As reviewed in this lecture, topological defect models of structure formation generically produce such a spectrum. We give a summary of the cosmic string and global texture models, focusing on distinct observational signatures in large-scale structure surveys and in the microwave background. It is shown that the amplitude of the CMB quadrupole detected by COBE is in good agreement with the predictions of the cosmic string model.
We analyze signals in the Cosmic Microwave Background (CMB) in theories where the small Dirac neutrino masses arise as a consequence of the compositeness of right-handed neutrinos. In such theories, the right-handed neutrinos are massless ``baryons'' of a new strong gauge interaction. We find that the results crucially depend on whether or not the new strong sector undergoes chiral symmetry breaking. In the case with chiral symmetry breaking, we find that there are indeed signals in the CMB, but none of them is a direct consequence of neutrino compositeness. In contrast, if the underlying theo…
We perform detailed calculations of cosmic microwave background (CMB) anisotropies in a CDM-dominated open universe with primordial adiabatic density perturbations for a variety of reionization histories. We show that to a great extent, the CMB anisotropies depend only on the geometry of the Universe, which in a matter dominated universe is determined by $Ω$, and the optical depth to the surface of last scattering. In particular, the location of the primary Doppler peak depends primarily on $Ω$ and is fairly insensitive to the other unknown parameters, such as $Ω_b$, $h$, $Λ$, and the shape of…
In the standard model of cosmology (SMC) the B-mode polarization of the CMB can be explained by the gravitational effects in the inflation epoch. However, this is not the only way to explain the B-mode polarization for the CMB. It can be shown that the Compton scattering in presence of a background besides generating a circularly polarized microwave, can leads to a B-mode polarization for the CMB. Here we consider the non-commutative (NC) space time as a background to explore the CMB polarization at the last scattering surface. We obtain the B-mode spectrum of the CMB radiation by scalar pertu…
Standard D-term inflation is studied in the framework of supergravity. D-term inflation produces cosmic strings, however it can still be compatible with CMB measurements without invoking any new physics. The cosmic strings contribution to the CMB data is not constant, nor dominant, contrary to some previous results. Using current CMB measurements, the free parameters (gauge and superpotential couplings, as well as the Fayet-Iliopoulos term) of D-term inflation are constrained.
I review two different connections between particle theory and early-Universe cosmology: (1) Cosmic-microwave-background (CMB) tests of inflation and (2) particle dark matter. The inflationary predictions of a flat Universe and a nearly scale-invariant spectrum of primordial density perturbations will be tested precisely with forthcoming maps of the CMB temperature. A stochastic gravitational-wave background may be probed with a map of the CMB polarization. I also discuss some other uses of CMB maps. Particle theory has produced two very well-motivated candidates for the dark matter in the Uni…
We study constraints on the natural inflation model from the cosmic microwave background radiation (CMBR). Inflaton ϕfor the natural inflation has a potential of the form V=Λ^4[1-\cos(ϕ/\sqrt{2}f_ϕ)], which is parametrized by two parameters f_ϕand Λ. Various cosmological quantities, like the primordial curvature perturbation and the CMBR anisotropy, are determined as functions of these two parameters. Using recent observations of the CMBR anisotropy by BOOMERANG and MAXIMA (as well as those from COBE), constraints on the parameters f_ϕand Λare derived. The model with f_ϕlower than 8.5\times 10…
The improved data on the cosmic microwave background (CMB) anisotropy allow a better determination of the adiabaticity of the primordial perturbation. Interestingly, we find that recent CMB data seem to favor a contribution of a primordial isocurvature mode where the entropy perturbation is positively correlated with the primordial curvature perturbation and has a large spectral index (niso ~ 3). With 4 additional parameters we obtain a better fit to the CMB data by Delta chi^2 = 9.7 compared to an adiabatic model. For this best-fit model the nonadiabatic contribution to the CMB temperature va…
We study the effect on the cosmic microwave background (CMB) anisotropy and large scale structure (LSS) power spectrum of a scattering interaction between cold dark matter and baryons. This scattering alters the CMB anisotropy and LSS spectrum through momentum transfer between the cold dark matter particles and the baryons. We find that current CMB observations can put an upper limit on the scattering cross section which is comparable with or slightly stronger than previous disk heating constraints at masses greater than 1 GeV, and much stronger at smaller masses. When large-scale structure co…
In the context of SUSY GUTs, GUT scale cosmic strings formed at the end of hybrid inflation are compatible with currently available CMB measurements. The maximum allowed cosmic strings contribution to the CMB data constrains the free parameters (mass scales, couplings) of inflationary models. For F-term inflation either the superpotential coupling must be fine tuned or one has to invoke the curvaton mechanism. D-term inflation should be addressed in the framework of SUGRA. We find that the cosmic strings contribution is not constant, contrary to some previous results. Using CMB measurements we…
The curl (B) modes of cosmic microwave background (CMB) polarization anisotropies are a unique probe of the primordial background of inflationary gravitational waves (IGWs). Unfortunately, the B-mode polarization anisotropies generated by gravitational waves at recombination are confused with those generated by the mixing of gradient-mode (E-mode) and B-mode polarization anisotropies as CMB photons propagate through the Universe and are gravitationally lensed. We describe here a method for delensing CMB polarization anisotropies using observations of anisotropies in the cosmic 21-cm radiation …
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