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Register a new userCosmological Constraints on the Higgs Boson Mass
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For a robust interpretation of upcoming observations from PLANCK and LHC experiments it is imperative to understand how the inflationary dynamics of a non-minimally coupled Higgs scalar field with gravity may affect the determination of the inflationary observables. We make a full proper analysis of the WMAP7+SN+BAO dataset in the context of the non-minimally coupled Higgs inflation field with gravity. For the central value of the top quark pole mass m_T=171.3 GeV, the fit of the inflation model with non-minimally coupled Higgs scalar field leads to the Higgs boson mass between 143.7 and 167 GeV (95% CL). We show that the inflation driven by a non-minimally coupled scalar field to the Einstein gravity leads to significant constraints on the scalar spectral index and tensor-to-scalar ratio when compared with the similar constraints tensor to from the standard inflation with minimally coupled scalar field. We also show that an accurate reconstruction of the Higgs potential in terms of inflationary observables requires an improved accuracy of other parameters of the Standard Model of particle physics as the top quark mass and the effective QCD coupling constant.
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We present the cosmological parameters constraints obtained from the combination of galaxy cluster mass function measurements (Vikhlinin et al., 2009a,b) with new cosmological data obtained during last three years: updated measurements of cosmic microwave background anisotropy with Wilkinson Microwave Anisotropy Probe (WMAP) observatory, and at smaller angular scales with South Pole Telescope (SPT), new Hubble constant measurements, baryon acoustic oscillations and supernovae Type Ia observations. New constraints on total neutrino mass and effective number of neutrino species are obtained. In models with free number of massive neutrinos the constraints on these parameters are notably less strong, and all considered cosmological data are consistent with non-zero total neutrino mass Sigma m_ u approx 0.4 eV and larger than standard effective number of neutrino species, N_eff approx 4. These constraints are compared to the results of neutrino oscillations searches at short baselines. The updated dark energy equation of state parameters constraints are presented. We show that taking in account systematic uncertainties, current cluster mass function data provide similarly powerful constraints on dark energy equation of state, as compared to the constraints from supernovae Type Ia observations.
Precision cosmology provides a sensitive probe of extremely weakly coupled states due to thermal freeze-in production, with subsequent decays impacting physics during well-tested cosmological epochs. We explore the cosmological implications of the freeze-in production of a new scalar $S$ via the super-renormalizable Higgs portal. If the mass of $S$ is at or below the electroweak scale, peak freeze-in production occurs during the electroweak epoch. We improve the calculation of the freeze-in abundance by including all relevant QCD and electroweak production channels. The resulting abundance and subsequent decay of $S$ is constrained by a combination of X-ray data, cosmic microwave background anisotropies and spectral distortions, $N_{rm eff}$, and the consistency of BBN with observations. These probes constrain technically natural couplings for such scalars from $m_S sim$ keV all the way to $m_S sim 100$ GeV. The ensuing constraints are similar in spirit to typical beam bump limits, but extend to much smaller couplings, down to mixing angles as small as $theta_{Sh} sim 10^{-16}$, and to masses all the way to the electroweak scale.
After a brief review of the muon g-2 status, we analyze the possibility that the present discrepancy between experiment and the Standard Model (SM) prediction may be due to hypothetical errors in the determination of the hadronic leading-order contribution to the latter. In particular, we show how an increase of the hadro-production cross section in low-energy e^+e^- collisions could bridge the muon g-2 discrepancy, leading however to a decrease on the electroweak upper bound on M_H, the SM Higgs boson mass. That bound is currently M_H < ~ 150GeV (95%CL) based on the preliminary top quark mass M_t = 172.6(1.4)GeV and the recent determination Delta alpha_{rm had}^{(5)}(M_Z) = 0.02768(22), while the direct-search lower bound is M_H > 114.4GeV (95%CL). By means of a detailed analysis we conclude that this solution of the muon g-2 discrepancy is unlikely in view of current experimental error estimates. However, if this turns out to be the solution, the 95%CL upper bound on M_H is reduced to about 130GeV which, in conjunction with the experimental lower bound, leaves a narrow window for the mass of this fundamental particle.
When combining cosmological and oscillations results to constrain the neutrino sector, the question of the propagation of systematic uncertainties is often raised. We address this issue in the context of the derivation of an upper bound on the sum of the neutrino masses ($Sigma m_ u$) with recent cosmological data. This work is performed within the ${{mathrm{Lambda{CDM}}}}$ model extended to $Sigma m_ u$, for which we advocate the use of three mass-degenerate neutrinos. We focus on the study of systematic uncertainties linked to the foregrounds modelling in CMB data analysis, and on the impact of the present knowledge of the reionisation optical depth. This is done through the use of different likelihoods built from Planck data. Limits on $Sigma m_ u$ are derived with various combinations of data, including the latest Baryon Acoustic Oscillations (BAO) and Type Ia Supernovae (SN) results. We also discuss the impact of the preference for current CMB data for amplitudes of the gravitational lensing distortions higher than expected within the ${{mathrm{Lambda{CDM}}}}$ model, and add the Planck CMB lensing. We then derive a robust upper limit: $Sigma m_ u< 0.17hbox{ eV at }95% hbox{CL}$, including 0.01 eV of foreground systematics. We also discuss the neutrino mass repartition and show that todays data do not allow one to disentangle normal from inverted hierarchy. The impact on the other cosmological parameters is also reported, for different assumptions on the neutrino mass repartition, and different high and low multipole CMB likelihoods.
We investigate the cosmological and astrophysical constraints on superconducting cosmic strings (SCSs). SCS loops emit strong bursts of electromagnetic waves, which might affect various cosmological and astrophysical observations. We take into account the effect on the CMB anisotropy, CMB blackbody spectrum, BBN, observational implications on radio wave burst and X-ray or gamma-ray events, and stochastic gravitational wave background measured by pulsar timing experiments. We then derive constraints on the parameters of SCS from current observations and estimate prospects for detecting SCS signatures in on-going observations. As a result, we find that these constraints exclude broad parameter regions, and also that on-going radio wave observations can probe large parameter space.
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