Search results for "Neutrino physics"
showing 10 items of 68 documents
Relaxing cosmological neutrino mass bounds with unstable neutrinos
2020
At present, cosmological observations set the most stringent bound on the neutrino mass scale. Within the standard cosmological model ($\Lambda$CDM), the Planck collaboration reports $\sum m_\nu < 0.12\,\text{eV}$ at 95% CL. This bound, taken at face value, excludes many neutrino mass models. However, unstable neutrinos, with lifetimes shorter than the age of the universe $\tau_\nu \lesssim t_U$, represent a particle physics avenue to relax this constraint. Motivated by this fact, we present a taxonomy of neutrino decay modes, categorizing them in terms of particle content and final decay products. Taking into account the relevant phenomenological bounds, our analysis shows that 2-body deca…
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…
Flavour violation at the LHC: type-I versus type-II seesaw in minimal supergravity
2009
20 pages, 13 figures.-- ISI article identifier:000267789100003.-- ArXiv pre-print avaible at:http://arxiv.org/abs/0903.1408
A model of neutrino mass and dark matter with large neutrinoless double beta decay
2017
We propose a model where neutrino masses are generated at three loop order but neutrinoless double beta decay occurs at one loop. Thus we can have large neutrinoless double beta decay observable in the future experiments even when the neutrino masses are very small. The model receives strong constraints from the neutrino data and lepton flavor violating decays, which substantially reduces the number of free parameters. Our model also opens up the possibility of having several new scalars below the TeV regime, which can be explored at the collider experiments. Additionally, our model also has an unbroken $Z_2$ symmetry which allows us to identify a viable Dark Matter candidate.
Resolving the octant of theta(23) with T2K and NOvA
2013
Preliminary results of MINOS experiment indicate that theta(23) is not maximal. Global fits to world neutrino data suggest two nearly degenerate solutions for theta(23): one in the lower octant (LO: theta(23) 45 degrees). v(mu) -> v(e) oscillations in superbeam experiments are sensitive to the octant and are capable of resolving this degeneracy. We study the prospects of this resolution by the current T2K and upcoming NOvA experiments. Because of the hierarchy-delta(CP) degeneracy and the octant delta(CP) degeneracy, the impact of hierarchy on octant resolution has to be taken into account. As in the case of hierarchy determination, there exist favorable (unfavorable) values of delta(CP) fo…
Minimal flavor violation in the see-saw portal
2020
We consider an extension of the Standard Model with two singlet leptons, with masses in the electroweak range, that induce neutrino masses via the see-saw mechanism, plus a generic new physics sector at a higher scale, $\Lambda$. We apply the minimal flavor violation (MFV) principle to the corresponding Effective Field Theory ($\nu$SMEFT) valid at energy scales $E \ll \Lambda$. We identify the irreducible sources of lepton flavor and lepton number violation at the renormalizable level, and apply the MFV ans\"atz to derive the scaling of the Wilson coefficients of the $\nu$SMEFT operators up to dimension six. We highlight the most important phenomenological consequences of this hypothesis in…
Probes of the Standard Model effective field theory extended with a right-handed neutrino
2019
If neutrinos are Dirac particles and, as suggested by the so far null LHC results, any new physics lies at energies well above the electroweak scale, the Standard Model effective field theory has to be extended with operators involving the right-handed neutrinos. In this paper, we study this effective field theory and set constraints on the different dimension-six interactions. To that aim, we use LHC searches for associated production of light (and tau) leptons with missing energy, monojet searches, as well as pion and tau decays. Our bounds are generally above the TeV for order one couplings. One particular exception is given by operators involving top quarks. These provide new signals in…
The seesaw portal in testable models of neutrino masses
2017
A Standard Model extension with two Majorana neutrinos can explain the measured neutrino masses and mixings, and also account for the matter-antimatter asymmetry in a region of parameter space that could be testable in future experiments. The testability of the model relies to some extent on its minimality. In this paper we address the possibility that the model might be extended by extra generic new physics which we parametrize in terms of a low-energy effective theory. We consider the effects of the operators of the lowest dimensionality, $d=5$, and evaluate the upper bounds on the coefficients so that the predictions of the minimal model are robust. One of the operators gives a new produ…
Minimal supersymmetric inverse seesaw: neutrino masses, lepton flavour violation and LHC phenomenology
2009
We study neutrino masses in the framework of the supersymmetric inverse seesaw model. Different from the non-supersymmetric version a minimal realization with just one pair of singlets is sufficient to explain all neutrino data. We compute the neutrino mass matrix up to 1-loop order and show how neutrino data can be described in terms of the model parameters. We then calculate rates for lepton flavour violating (LFV) processes, such as mu -> e gamma and chargino decays to singlet scalar neutrinos. The latter decays are potentially observable at the LHC and show a characteristic decay pattern dictated by the same parameters which generate the observed large neutrino angles.