Higgs inflation: consistency and generalisations

We analyse the self-consistency of inflation in the Standard Model, where the Higgs field has a large non-minimal coupling to gravity. We determine the domain of energies in which this model represents a valid effective field theory as a function of the background Higgs field. This domain is bounded above by the cutoff scale which is found to be higher than the relevant dynamical scales throughout the whole history of the Universe, including the inflationary epoch and reheating. We present a systematic scheme to take into account quantum loop corrections to the inflationary calculations within the framework of effective field theory. We discuss the additional assumptions that must be satisfied by the ultra-violet completion of the theory to allow connection between the parameters of the inflationary effective theory and those describing the low-energy physics relevant for the collider experiments. A class of generalisations of inflationary theories with similar properties is constructed.Comment: 25 pages, 1 figur

The Λ0\Lambda_0 Polarization and the Recombination Mechanism

We use the recombination and the Thomas Precession Model to obtain a prediction for the $\Lambda _0$ polarization in the $p+p \to \Lambda_0+X$ reaction. We study the effect of the recombination function on the $\Lambda_0$ polarization.Comment: 4 pages, LaTex, 1 figures included, aipproc.sty included. Talk presented at Simposio Latino Americano de Fisica de Altas Energias, Merida, Mexico, November 199

Liesegang patterns : Studies on the width law

The so-called "width law" for Liesegang patterns, which states that the positions x_n and widths w_n of bands verify the relation x_n \sim w_n^{\alpha} for some \alpha>0, is investigated both experimentally and theoretically. We provide experimental data exhibiting good evidence for values of \alpha close to 1. The value \alpha=1 is supported by theoretical arguments based on a generic model of reaction-diffusion.Comment: 7 pages, RevTeX, two columns, 5 figure

Low-threshold calcium spike bursts in the human thalamus: Common physiopathology for sensory, motor and limbic positive symptoms

Positive symptoms arise after lesions of the nervous system. They include neurogenic pain, tinnitus, abnormal movements, epilepsy and certain neuropsychiatric disorders. Stereotactic medial thalamotomies were performed on 104 patients with chronic therapy-resistant positive symptoms. Peroperative recordings of 2012 single units revealed an overwhelming unresponsiveness (99%) to sensory stimuli or motor activation. Among these unresponsive cells, 45.1% presented a rhythmic or random bursting activity. Rhythmic bursting activities had an average interburst interval of 263±46 ms corresponding to a frequency of 3.8±0.7 Hz. Frequency variations among the different symptoms were not statistically different. Intraburst characteristics such as the highest frequency encountered in the burst (480±80 Hz) or the mean frequency of the burst (206±44 Hz) were also similar in all patients. All bursts, rhythmic or random, fulfilled the extracellular criteria of low-threshold calcium spike (LTS) bursts. After medial thalamotomy and depending on the symptom, 43-67% of the patients reached a 50-100% relief, with sparing of all neurological functions. On the basis of these electrophysiological and clinical results, we propose a unified concept for all positive symptoms centred on a self-perpetuating thalamic cell membrane hyperpolarization, similar to the one seen in slow-wave slee

Derivation of the Matalon-Packter law for Liesegang patterns

Theoretical models of the Liesegang phenomena are studied and simple expressions for the spacing coefficients characterizing the patterns are derived. The emphasis is on displaying the explicit dependences on the concentrations of the inner- and the outer-electrolytes. Competing theories (ion-product supersaturation, nucleation and droplet growth, induced sol- coagulation) are treated with the aim of finding the distinguishing features of the theories. The predictions are compared with experiments and the results suggest that the induced sol-coagulation theory is the best candidate for describing the experimental observations embodied in the Matalon-Packter law.Comment: 9 pages, 7 figures, RevTe

Formation of Liesegang patterns: Simulations using a kinetic Ising model

A kinetic Ising model description of Liesegang phenomena is studied using Monte Carlo simulations. The model takes into account thermal fluctuations, contains noise in the chemical reactions, and its control parameters are experimentally accessible. We find that noisy, irregular precipitation takes place in dimension d=2 while, depending on the values of the control parameters, either irregular patterns or precipitation bands satisfying the regular spacing law emerge in d=3.Comment: 7 pages, 8 ps figures, RevTe

Low Q2Q^2 wave-functions of pions and kaons and their parton distribution functions

We study the low $Q^2$ wave-functions of pions and kaons as an expansion in terms of hadron-like Fock state fluctuations. In this formalism, pion and kaon wave-functions are related one another. Consequently, the knowledge of the pion structure allows the determination of parton distributions in kaons. In addition, we show that the intrinsic (low $Q^2$) sea of pions and kaons are different due to their different valence quark structure. Finally, we analize the feasibility of a method to extract kaon's parton distribution functions within this approach and compare with available experimental data.Comment: 13 pages, 3 postscript figures include

Gluon distributions in nucleons and pions at a low resolution scale

In this paper we study the gluon distribution functions in nucleons and pions at a low resolution $Q^2$ scale. This is an important issue since parton densities at low $Q^2$ have always been taken as an external input which is adjusted through DGLAP evolution to fit the experimental data at higher scales. Here, in the framework of a model recently developed, it is shown that the hypothetical cloud of {\it neutral} pions surrounding nucleons and pions appears to be responsible for the characteristic valence-like gluon distributions needed at the inital low scale. As an additional result, we get the remarkable prediction that neutral and charged pions have different intrinsic sea flavor contents.Comment: final version to appear in Phys. Rev. D. Discussion on several points enlarge