262,460 research outputs found
Higgs boson and Top quark masses as tests of Electroweak Vacuum Stability
No full textThe measurements of the Higgs boson and top quark masses can be used to extrapolate the Standard Model Higgs potential at energies up to the Planck scale. Adopting a Next-to-Next- to-Leading Order renormalization procedure, we argue that electroweak vacuum stability is at present allowed, discuss the associated theoretical and experimental errors and the prospects for its future tests.The measurements of the Higgs boson and top quark masses can be used to extrapolate the Standard Model Higgs potential at energies up to the Planck scale. Adopting a Next-to-Next-to-Leading Order renormalization procedure, we argue that electroweak vacuum stability is at present allowed, discuss the associated theoretical and experimental errors and the prospects for its future tests. © Copyright owned by the author(s)
Dark matter and dark radiation from evaporating primordial black holes
No full textPrimordial black holes in the mass range from to g might have existed in the early universe. Via their evaporation mechanism (completed before Big Bang Nucleosynthesis), they might have released stable particles beyond the Standard Model. We reconsider the possibility that such particles might constitute the main part or a fraction of the dark matter observed today, updating the impact on this scenario from warm dark matter constraints. If sufficiently light, stable particles from primordial black holes evaporation might also provide a significant contribution to dark radiation. We generalize previous studies on this interesting dark matter and dark radiation production mechanism, by including the effects of accretion and a possible amount of entropy nonconservation. We also discuss in some detail specific examples of stable particle candidates beyond the Standard Model.Primordial black holes in the mass range from to g might have existed in the early universe. Via their evaporation mechanism (completed before Big Bang Nucleosynthesis), they might have released stable particles beyond the Standard Model. We reconsider the possibility that such particles might constitute the main part or a fraction of the dark matter observed today, updating the impact on this scenario from warm dark matter constraints. If sufficiently light, stable particles from primordial black holes evaporation might also provide a significant contribution to dark radiation. We generalize previous studies on this interesting dark matter and dark radiation production mechanism, by including the effects of accretion and a possible amount of entropy non conservation. We also discuss in some detail specific examples of stable particle candidates beyond the Standard Model
Dark matter from evaporating Black Holes
No full textLight primordial black holes (PBHs) are an ideal particle factory: they emit all existing particles – of the Standard Model (SM) or beyond it – whose mass is smaller than the PBHs Hawking temperature. Evaporation of PBHs is thus an interesting mechanism for Dark Matter (DM) production. We review the status of the art of this possibility, analyzing in particular the effects of the DM particle spin, for both Schwarzschild and Kerr PBHs
Triad’s consonance and dissonance: a detailed analysis of compactness models
No full textTheories of consonance and dissonance based on the "compactness" approach include the two sub-categories of periodicity and harmonicity. In a previous work, we discussed the related consonance and dissonance indicators for dyads; as they are given by discontinuous functions of the dyad frequency ratio, we proposed a method to extend them to the continuum, based on the auditory discrimination limen. Here, we generalize the compactness indicators to describe the consonance and dissonance for triads and discuss their extension to the continuum. We compare our model predictions with perceptual data from a recent psychoacoustic test by means of a Chi-square analysis. The result is that compactness indicators provide a quite effective, but not fully satisfactory, description of consonance, and dissonance for triads
Alternativni pogon kod teskih traktora gusenicara i radnih masina
No full textRazvoj gusenicara sa elektricnom transmisijom, Cat D7E, pocinje krajem XX veka kao masine indikatora buducih pravaca i dizajnu i razvoju teski tipova traktota gusenicara, (Caterpillar, Illionis, U.S.A.
Prelazak na sistemu sa elektricnom transmisijom kao jednim od oblika alternativnih pogona, pruza znacajne prednosti u poredzenju sa klasicnim sistemima pogona (mehanickim prenosnim sistemom, hidrostatickim prenosnim sistema)jer konceocija gusenicara Cat D7E predvidza put kojim moze krenuti razvoj alternativnih pogona teski radnih i drugih masina u skoroj buducnosti.
Ovde pocnuje budiucnost sledeci vek teskih radnih masina, izjavili su konstruktori kompanije caterpillar - U.S.A, 2010 godina, prilokom ekperimentalnom ispitivanja traktora gusenicara Cat D7E. Zasto? Preazak na sistem elektricne transmisije, koa oblika alternativnok pogona, kod teskih traktora gusenicara, na primer, Cat D7E, ima znacejne prednosti u poredzenju sa mehanickim sistemom prenosa snage kod slicnih modela teskih traktora gusenicara ili drugih slicnih radnih masina, koje ce biti prestavljene u radu
Looking for a charge asymmetry in cosmic rays
No full textWe combine the data from PAMELA and FERMI-LAT cosmic ray experiments by introducing a simple sum rule. This allows to investigate whether the lepton excess observed by these experiments is charge symmetric or not. We also show how the data can be used to predict the positron fraction at energies yet to be explored by the AMS-02 experiment
Electroweak metastability and Higgs inflation
No full textExtrapolating the Standard Model Higgs potential at high energies, we study the barrier between the electroweak and Planck scale minima. The barrier arises by taking the central values of the relevant experimental inputs, that is the strong coupling constant and the top quark and Higgs masses. We then extend the Standard Model by including a non-minimal coupling to gravity, and explore the phenomenology of the Higgs inflation model. We point out that even configurations that would be metastable in the Standard Model, become viable for inflation if the non-minimal coupling is large enough to flatten the Higgs potential at field values below the barrier; we find that the required value of the non-minimal coupling is smaller than the one needed for the conventional Higgs inflation scenario (which relies on a stable Standard Model Higgs potential, without any barrier); in addition, values of the top mass which are larger than those required in the conventional scenario are allowed
Phenomenology of the seesaw mechanism
No full textAfter a brief summary about fermion masses and mixings, I will introduce the seesaw mechanism, digress on the difficulties found in constructing viable models of flavor, and conclude by addressing a couple of phenomenological aspects associated with the seesaw
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