Search results for "Particle physics"
showing 10 items of 6826 documents
Neutrino Mass from Cosmology
2012
Neutrinos can play an important role in the evolution of the Universe, modifying some of the cosmological observables. In this contribution we summarize the main aspects of cosmological relic neutrinos and we describe how the precision of present cosmological data can be used to learn about neutrino properties, in particular their mass, providing complementary information to beta decay and neutrinoless double-beta decay experiments. We show how the analysis of current cosmological observations, such as the anisotropies of the cosmic microwave background or the distribution of large-scale structure, provides an upper bound on the sum of neutrino masses of order 1 eV or less, with very good p…
Direct and indirect singlet scalar dark matter detection in the lepton-specific two-Higgs-doublet model
2011
A recent study of gamma-ray data from the Galactic Center motivates the investigation of light (~7-10 GeV) particle dark matter models featuring tau lepton pairs as dominant annihilation final state. The Lepton-Specific two-Higgs-doublet Model (2HDM-L) provides a natural framework where light, singlet scalar dark matter can pair-annihilate dominantly into tau leptons. We calculate the nucleon-dark matter cross section for singlet scalar dark matter within the 2HDM-L framework, and compare with recent results from direct detection experiments. We study how direct dark matter searches can be used to constrain the dark matter interpretation of gamma ray observations, for different dominant ann…
Bounds on very low reheating scenarios after Planck
2015
9 pages.- 9 figures
Shining Light on the Scotogenic Model: Interplay of Colliders and Cosmology
2019
In the framework of the scotogenic model, which features radiative generation of neutrino masses, we explore light dark matter scenario. Throughout the paper we chiefly focus on keV-scale dark matter which can be produced either via freeze-in through the decays of the new scalars, or from the decays of next-to-lightest fermionic particle in the spectrum, which is produced through freeze-out. The latter mechanism is required to be suppressed as it typically produces a hot dark matter component. Constraints from BBN are also considered and in combination with the former production mechanism they impose the dark matter to be light. For this scenario we consider signatures at High Luminosity LH…
2020 global reassessment of the neutrino oscillation picture
2021
We present an updated global fit of neutrino oscillation data in the simplest three-neutrino framework. In the present study we include up-to-date analyses from a number of experiments. Concerning the atmospheric and solar sectors, we give updated analyses of DeepCore and SNO data, respectively. We have also included the latest electron antineutrino data collected by the Daya Bay and RENO reactor experiments, and the long-baseline T2K and NO$\nu$A measurements. These new analyses result in more accurate measurements of $\theta_{13}$, $\theta_{12}$, $\Delta m_{21}^2$ and $|\Delta m_{31}^2|$. The best fit value for the atmospheric angle $\theta_{23}$ lies in the second octant, but first octan…
Reliability of Monte Carlo event generators for gamma-ray dark matter searches
2013
We study the differences in the gamma-ray spectra simulated by four Monte Carlo event generator packages developed in particle physics. Two different versions of PYTHIA and two of HERWIG are analyzed, namely PYTHIA 6.418 and HERWIG 6.5.10 in Fortran and PYTHIA 8.165 and HERWIG 2.6.1 in C++. For all the studied channels, the intrinsic differences between them are shown to be significative and may play an important role in misunderstanding dark matter signals.
Parity-violating interactions of cosmic fields with atoms, molecules, and nuclei: Concepts and calculations for laboratory searches and extracting li…
2014
We propose methods and present calculations that can be used to search for evidence of cosmic fields by investigating the parity-violating effects, including parity nonconservation amplitudes and electric dipole moments, that they induce in atoms. The results are used to constrain important fundamental parameters describing the strength of the interaction of various cosmic fields with electrons, protons, and neutrons. Candidates for such fields are dark matter (including axions) and dark energy, as well as several more exotic sources described by standard-model extensions. Existing parity nonconservation experiments in Cs, Dy, Yb, and Tl are combined with our calculations to directly place …
New generation low-energy probes for ultralight axion and scalar dark matter
2017
We present a brief overview of a new generation of high-precision laboratory and astrophysical measurements to search for ultralight (sub-eV) axion, axion-like pseudoscalar and scalar dark matter, which form either a coherent condensate or topological defects (solitons). In these new detection methods, the sought effects are linear in the interaction constant between dark matter and ordinary matter, which is in stark contrast to traditional searches for dark matter, where the sought effects are quadratic or higher order in the underlying interaction constants (which are extremely small).
The Dispirited Case of Gauged $U(1)_{B-L}$ Dark Matter
2018
We explore the constraints and phenomenology of possibly the simplest scenario that could account at the same time for the active neutrino masses and the dark matter in the Universe within a gauged $U(1)_{B-L}$ symmetry, namely right-handed neutrino dark matter. We find that null searches from lepton and hadron colliders require dark matter with a mass below 900 GeV to annihilate through a resonance. Additionally, the very strong constraints from high-energy dilepton searches fully exclude the model for $ 150 \, \text{GeV} < m_{Z'} < 3 \, \text{TeV}$. We further explore the phenomenology in the high mass region (i.e. masses $\gtrsim \mathcal{O}(1) \, \text{TeV}$) and highlight theoret…
Discrete dark matter
2010
We propose a new motivation for the stability of dark matter (DM). We suggest that the same non-abelian discrete flavor symmetry which accounts for the observed pattern of neutrino oscillations, spontaneously breaks to a Z2 subgroup which renders DM stable. The simplest scheme leads to a scalar doublet DM potentially detectable in nuclear recoil experiments, inverse neutrino mass hierarchy, hence a neutrinoless double beta decay rate accessible to upcoming searches, while reactor angle equal to zero gives no CP violation in neutrino oscillations.