50 research outputs found
Neutrino Mass Sum Rules and Symmetries of the Mass Matrix
Neutrino mass sum rules have recently gained again more attention as a
powerful tool to discriminate and test various flavour models in the near
future. A related question which was not yet discussed fully satisfactorily was
the origin of these sum rules and if they are related to any residual or
accidental symmetry. We will address this open issue here systematically and
find previous statements confirmed. Namely, that the sum rules are not related
to any enhanced symmetry of the Lagrangian after family symmetry breaking but
that they are simply the result of a reduction of free parameters due to
skillful model building.Comment: 10 pages, no figures, accepted for publication in European Physical
Journal
Renormalisation Group Corrections to Neutrino Mass Sum Rules
Neutrino mass sum rules are an important class of predictions in flavour
models relating the Majorana phases to the neutrino masses. This leads, for
instance, to enormous restrictions on the effective mass as probed in
experiments on neutrinoless double beta decay. While up to now these sum rules
have in practically all cases been taken to hold exactly, we will go here
beyond that. After a discussion of the types of corrections that could possibly
appear and elucidating on the theory behind neutrino mass sum rules, we
estimate and explicitly compute the impact of radiative corrections, as these
appear in general and thus hold for whole groups of models. We discuss all
neutrino mass sum rules currently present in the literature, which together
have realisations in more than 50 explicit neutrino flavour models. We find
that, while the effect of the renormalisation group running can be visible, the
qualitative features do not change. This finding strongly backs up the solidity
of the predictions derived in the literature, and it thus marks a very
important step in deriving testable and reliable predictions from neutrino
flavour models.Comment: 25 pages, 3 figures, 39 additional plots; version published in JHE
Neutrino windows to new physics
Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física Teórica. Fecha de lectura: 25-06-201
A testable hidden-sector model for Dark Matter and neutrino masses
We consider a minimal extension of the Standard Model with a hidden sector charged under a dark local U(1)′ gauge group, accounting simultaneously for light neutrino masses and the observed Dark Matter relic abundance. The model contains two copies of right-handed neutrinos which give rise to light neutrino-masses via an extended seesaw mechanism. The presence of a stable Dark-Matter candidate and a massless state naturally arise by requiring the simplest anomaly-free particle content without introducing any extra symmetries. We investigate the phenomenology of the hidden sector considering the U(1)′ breaking scale of the order of the electroweak scale. Confronting the thermal history of this hidden-sector model with existing and future constraints from collider, direct and indirect detection experiments provides various possibilities of probing the model in complementary ways as every particle of the dark sector plays a specific cosmological role. Across the identified viable parameter space, a large region predicts a sizable contribution to the effective relativistic degrees-of-freedom in the early Universe that allows to alleviate the recently reported tension between late and early measurements of the Hubble constantThe work of MP was supported by the Spanish Agencia Estatal de Investigación through the grants FPA2015-65929-P (MINECO/FEDER, UE), PGC2018-095161-B-I00, IFT Centro de Excelencia Severo Ochoa SEV-2016-0597, and Red Consolider MultiDark FPA2017-90566-REDC. MP would like to thank the Lawrence Berkeley National Laboratory for its hospitality during part of the realization of this work as well as the Paris-Saclay Particle Symposium 2019 with the support of the P2I and SPU research departments and the P2IO Laboratory of Excellence (program “Investissements d’avenir” ANR-11-IDEX-0003-01 Paris-Saclay and ANR-10-LABX-0038), as well as the IPhT. This project has received funding/support from the European Unions Horizon 2020 research and innovation programme under the Marie Skodowska-Curie grant agreements Elusives ITN No. 674896 and InvisiblesPlus RISE No. 690575. J.G. is supported by the US Department of Energy under Grant Contract DE-SC001270
Long-lived bio at the LHC
We examine the detection prospects for a long-lived bio, a pseudo-Dirac
bino which is responsible for neutrino masses, at the LHC and at dedicated
long-lived particle detectors. The bio arises in -symmetric
supersymmetric models where the neutrino masses are generated through higher
dimensional operators in an inverse seesaw mechanism. At the LHC the bio
is produced through squark decays and it subsequently decays to quarks, charged
leptons and missing energy via its mixing with the Standard Model neutrinos. We
consider long-lived bios which escape the ATLAS or CMS detectors as
missing energy and decay to charged leptons inside the proposed long-lived
particle detectors FASER, CODEX-b, and MATHUSLA. We find the currently allowed
region in the squark-bio mass parameter space by recasting most recent LHC
searches for jets+MET. We also determine the reach of MATHUSLA, CODEX-b and
FASER. We find that a large region of parameter space involving squark masses,
bio mass and the messenger scale can be probed with MATHUSLA, ranging from
bio masses of 10 GeV-2 TeV and messenger scales TeV for a
range of squark masses.Comment: 15 pages, 4 figure
Neutrino Constraints and the ATOMKI X17 Anomaly
Recent data from the ATOMKI group continues to confirm their claim of the
existence of a new MeV particle. We review and numerically analyze the
data and then put into context constraints from other experiments, notably
neutrino scattering experiments such as the latest reactor anti-neutrino
coherent elastic neutrino nucleus scattering data and unitarity constraints
from solar neutrino observations. We show that minimal scenarios are disfavored
and discuss the model requirements to evade these constraints.Comment: 11 pages, 4 figures, comments welcome! v2: analysis expanded, results
similar, matches published versio
Here Comes the Sun: Solar Parameters in Long-Baseline Accelerator Neutrino Oscillations
Long-baseline (LBL) accelerator neutrino oscillation experiments, such as
NOvA and T2K in the current generation, and DUNE-LBL and HK-LBL in the coming
years, will measure the remaining unknown oscillation parameters with excellent
precision. These analyses assume external input on the so-called ``solar
parameters,'' and , from solar experiments such
as SNO, SK, and Borexino, as well as reactor experiments like KamLAND. Here we
investigate their role in long-baseline experiments. We show that, without
external input on and , the sensitivity to
detecting and quantifying CP violation is significantly, but not entirely,
reduced. Thus long-baseline accelerator experiments can actually determine
and , and thus all six oscillation parameters,
without input from \emph{any} other oscillation experiment. In particular,
can be determined; thus DUNE-LBL and HK-LBL can measure both
the solar and atmospheric mass splittings in their long-baseline analyses
alone. While their sensitivities are not competitive with existing constraints,
they are very orthogonal probes of solar parameters and provide a key
consistency check of a less probed sector of the three-flavor oscillation
picture. Furthermore, we also show that the true values of
and play an important role in the sensitivity of other
oscillation parameters such as the CP violating phase .Comment: 29 pages, 13 figures, comments welcome! v2: matches published versio