First second of leptons

A poorly constrained parameter in the Standard Model of Cosmology is the lepton asymmetry l = \sum_f l_f=\sum_f(n_f+n_{\nu_f})/s. Each flavour asymmetry l_f with f=e, \mu, {\tau} is the sum of the net particle density of the charged leptons n_f and their corresponding neutrinos, normalized with the entropy density s. Constraints on l_f \leq O(0.1) from BBN and CMB allow for lepton flavour asymmetries orders of magnitudes larger then the baryon asymmetry b ~ 10^{-10}. In this article we show how such large lepton (flavour) asymmetries influence the early universe, in particular the freeze out of WIMPs and the cosmic QCD transition.Comment: 4 pages, 2 figures; prepared for the 12th international conference on Topics in Astroparticle and Underground Physics, TAUP2011. v2: matches accepted versio

The first second of leptons

Stuke M. The first second of leptons. Bielefeld (Germany): Bielefeld University; 2011.We study the influence of lepton asymmetries on the evolution of the early Universe. The lepton asymmetry l is poorly constrained by observations and might be orders of magnitudes larger than the observed baryon asymmetry b~O(10^{-10}), |l|/b~O(10^9). We find that lepton asymmetries large compared to the tiny baryon asymmetry, can influence the dynamics of the QCD phase transition significantly. The cosmic trajectory in the mu_{B}-T phase diagram of strongly interacting matter becomes a function of lepton (flavour) asymmetry. For tiny or vanishing baryon and lepton asymmetries lattice QCD simulations show that the cosmic QCD transition is a rapid crossover. However, for large lepton asymmetry, the order of the cosmic transition remains unknown. We find that a large asymmetry in one or more lepton flavour changes the number of helicity degrees of freedom of all particles in equilibrium g_{ast} significantly. For the relic abundance of WIMPs, depending on g_{ast} of all particles at the freeze out temperature 40 GeV > T_fo > 0.4 GeV we find a decreasing of few percent depending on l_f . For an asymmetry of l_f = 0.1 in all three flavour we find a decrease of the relic WIMP abundance for a given freeze out temperature of almost 20 percent

Neuropsychological Testing and Machine Learning Distinguish Alzheimer’s Disease from Other Causes for Cognitive Impairment

With promising results in recent treatment trials for Alzheimer’s disease (AD), it becomes increasingly important to distinguish AD at early stages from other causes for cognitive impairment. However, existing diagnostic methods are either invasive (lumbar punctures, PET) or inaccurate Magnetic Resonance Imaging (MRI). This study investigates the potential of neuropsychological testing (NPT) to specifically identify those patients with possible AD among a sample of 158 patients with Mild Cognitive Impairment (MCI) or dementia for various causes. Patients were divided into an early stage and a late stage group according to their Mini Mental State Examination (MMSE) score and labeled as AD or non-AD patients based on a post-mortem validated threshold of the ratio between total tau and beta amyloid in the cerebrospinal fluid (CSF; Total tau/Aβ(1–42) ratio, TB ratio). All patients completed the established Consortium to Establish a Registry for Alzheimer’s Disease—Neuropsychological Assessment Battery (CERAD-NAB) test battery and two additional newly-developed neuropsychological tests (recollection and verbal comprehension) that aimed at carving out specific Alzheimer-typical deficits. Based on these test results, an underlying AD (pathologically increased TB ratio) was predicted with a machine learning algorithm. To this end, the algorithm was trained in each case on all patients except the one to predict (leave-one-out validation). In the total group, 82% of the patients could be correctly identified as AD or non-AD. In the early group with small general cognitive impairment, classification accuracy was increased to 89%. NPT thus seems to be capable of discriminating between AD patients and patients with cognitive impairment due to other neurodegenerative or vascular causes with a high accuracy, and may be used for screening in clinical routine and drug studies, especially in the early course of this disease

Effects of a Cut, Lorentz-Boosted sky on the Angular Power Spectrum

The largest fluctuation in the observed CMB temperature field is the dipole, its origin being usually attributed to the Doppler Effect - the Earth's velocity with respect to the CMB rest frame. The lowest order boost correction to temperature multipolar coefficients appears only as a second order correction in the temperature power spectrum, $C_{\ell}$. Since v/c - 10-3, this effect can be safely ignored when estimating cosmological parameters [4-7]. However, by cutting our galaxy from the CMB sky we induce large-angle anisotropies in the data. In this case, the corrections to the cut-sky $C_{\ell}$s show up already at first order in the boost parameter. In this paper we investigate this issue and argue that this effect might turn out to be important when reconstructing the power spectrum from the cut-sky data.Comment: 12 pages, 1 figur