Search results for "Particle physics"
showing 10 items of 6826 documents
Gravity-mediated Scalar Dark Matter in Warped Extra-Dimensions
2020
We revisit the case of scalar dark matter interacting just gravitationally with the Standard Model (SM) particles in an extra-dimensional Randall-Sundrum scenario. We assume that both, the dark matter and the Standard Model, are localized in the TeV brane and only interact via gravitational mediators, namely the graviton Kaluza-Klein modes and the radion. We analyze in detail the dark matter annihilation channel into two on-shell KK-gravitons, and contrary to previous studies which overlooked this process, we find that it is possible to obtain the correct relic abundance for dark matter masses in the range [1, 10] TeV even after taking into account the strong bounds from LHC Run II. We also…
Collective flavor transitions of supernova neutrinos
2009
We give a very brief overview of collective effects in neutrino oscillations in core collapse supernovae where refractive effects of neutrinos on themselves can considerably modify flavor oscillations, with possible repercussions for future supernova neutrino detection. We discuss synchronized and bipolar oscillations, the role of energy and angular neutrino modes, as well as three-flavor effects. We close with a short summary and some open questions.
Aidnogenesis via Leptogenesis and Dark Sphalerons
2010
We discuss aidnogenesis, the generation of a dark matter asymmetry via new sphaleron processes associated to an extra non-abelian gauge symmetry common to both the visible and the dark sectors. Such a theory can naturally produce an abundance of asymmetric dark matter which is of the same size as the lepton and baryon asymmetries, as suggested by the similar sizes of the observed baryonic and dark matter energy content, and provide a definite prediction for the mass of the dark matter particle. We discuss in detail a minimal realization in which the Standard Model is only extended by dark matter fermions which form "dark baryons" through an SU(3) interaction, and a (broken) horizontal symme…
Analysis of the 4-year IceCube high-energy starting events
2016
After four years of data taking, the IceCube neutrino telescope has detected 54 high-energy starting events (HESE, or contained-vertex events) with deposited energies above 20TeV. They represent the first ever detection of high-energy extraterrestrial neutrinos and therefore, the first step in neutrino astronomy. In order to study the energy, flavor and isotropy of the astrophysical neutrino flux arriving at Earth, we perform different analyses of two different deposited energy intervals, [10 TeV $-$ 10 PeV] and [60 TeV $-$ 10 PeV]. We first consider an isotropic unbroken power-law spectrum and constrain its shape, normalization and flavor composition. Our results are in agreement with the …
Flavor of cosmic neutrinos preserved by ultralight dark matter
2019
Within the standard propagation scenario, the flavor ratios of high-energy cosmic neutrinos at neutrino telescopes are expected to be around the democratic benchmark resulting from hadronic sources, $\left( 1 : 1 : 1 \right)_\oplus$. We show how the coupling of neutrinos to an ultralight dark matter complex scalar field would induce an effective neutrino mass that could lead to adiabatic neutrino propagation. This would result in the preservation at the detector of the production flavor composition of neutrinos at sources. This effect could lead to flavor ratios at detectors well outside the range predicted by the standard scenario of averaged oscillations. We also present an electroweak-in…
Fuzzy Dark Matter and Non-Standard Neutrino Interactions
2018
We discuss novel ways in which neutrino oscillation experiments can probe dark matter. In particular, we focus on interactions between neutrinos and ultra-light ("fuzzy") dark matter particles with masses of order $10^{-22}$ eV. It has been shown previously that such dark matter candidates are phenomenologically successful and might help ameliorate the tension between predicted and observed small scale structures in the Universe. We argue that coherent forward scattering of neutrinos on fuzzy dark matter particles can significantly alter neutrino oscillation probabilities. These effects could be observable in current and future experiments. We set new limits on fuzzy dark matter interacting…
Constraints on millicharged dark matter and axionlike particles from timing of radio waves
2019
We derive novel constraints on millicharged dark matter and ultralight axion-like particles using pulsar timing and fast radio burst observations. Millicharged dark matter affects the dispersion measure of the time of arrival of radio pulses in a way analogous to free electrons. Light pseudo-scalar dark matter, on the other hand, causes the polarization angle of radio signals to oscillate. We show that current and future data can set strong constraints in both cases. For dark matter particles of charge $\epsilon e$, these constraints are ${\epsilon}/{m_{\rm milli}} \lesssim 10^{-8}{\rm eV}^{-1}$, for masses $m_{\rm milli}\gtrsim 10^{-6}\,$eV. For axion-like particles, the analysis of signal…
Global fits of the SM parameters
2019
I present a global survey of weak mixing angle measurements and other precision experiments and discuss the issue of correlations of the theoretical uncertainties in precision observables. Hadronic vacuum polarization effects complicate global fits in various ways and are also covered alongside some representative fit results.
Precision measurement of the K S meson lifetime with the KLOE detector
2010
Using a large sample of pure, slow, short lived K0 mesons collected with KLOE detector at DaFne, we have measured the KS lifetime. From a fit to the proper time distribution we find tau = (89.562 +- 0.029_stat +- 0.043_syst) ps. This is the most precise measurement today in good agreement with the world average derived from previous measurements. We observe no dependence of the lifetime on the direction of the Ks.
QED box amplitude in heavy fermion production
2002
We evaluate the two-photon box contribution to heavy fermion production in electron positron annihilation, that provides O(alpha^2) electromagnetic corrections to the Born cross section. The study of its non-relativistic expansion, relevant at energies close to the threshold of production, is also performed. We also verify that the threshold expansion of the one-loop integrals correctly reproduces our results, thus extending the applicability of this technique to heavy fermion production diagrams.