arXiv subjects

José W. F. Valle

Publications and source records attributed to José W. F. Valle.

At least 73 records · Page 4Linked to original sources

arXiv2018

Zooming in on neutrino oscillations with DUNE

We examine the capabilities of the DUNE experiment as a probe of the neutrino mixing paradigm. Taking the current status of neutrino oscillations and the design specifications of DUNE, we determine the experiment's potential to probe the structure of neutrino mixing and CP violation. We focus on the poorly determined parameters $θ_{23}$ and $δ_{CP}$ and consider both two and seven years of run. We take various benchmarks as our true values, such as the current preferred values of $θ_{23}$ and $δ_{CP}$, as well as several theory-motivated choices. We determine quantitatively DUNE's potential to perform a precision measurement of $θ_{23}$, as well as to test the CP violation hypothesis in a model-independent way. We find that, after running for seven years, DUNE will make a substantial step in the precise determination of these parameters, bringing to quantitative test the predictions of various theories of neutrino mixing.

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arXiv2018

Asymmetric Dark Matter, Inflation and Leptogenesis from B-L Symmetry Breaking

We propose a unified setup for dark matter, inflation and baryon asymmetry generation through the neutrino mass seesaw mechanism. Our scenario emerges naturally from an extended gauge group containing $B-L$ as a non-commutative symmetry, broken by a singlet scalar that also drives inflation. Its decays reheat the universe, producing the lightest right-handed neutrino. Automatic matter parity conservation leads to the stability of an asymmetric dark matter candidate, directly linked to the matter-antimatter asymmetry in the universe.

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arXiv2018

Seesaw roadmap to neutrino mass and dark matter

We describe the many pathways to generate Majorana and Dirac neutrino mass through generalized dimension-5 operators a la Weinberg. The presence of new scalars beyond the Standard Model Higgs doublet implies new possible field contractions, which are required in the case of Dirac neutrinos. We also notice that, in the Dirac neutrino case, the extra symmetries needed to ensure the Dirac nature of neutrinos can also be made responsible for stability of dark matter.

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arXiv2018

Seesaw Dirac neutrino mass through dimension-6 operators

In this paper, a followup of arXiv: 1802.05722, we describe the many pathways to generate Dirac neutrino mass through dimension-6 operators. By using only the Standard Model Higgs doublet in the external legs one gets a unique operator $\frac{1}{Λ^2} \, \bar{L}\, \barΦ \, \barΦ \, Φ\, ν_R $. In contrast, the presence of new scalars implies new possible field contractions, which greatly increase the number of possibilities. Here we study in detail the simplest ones, involving $SU(2)_L$ singlets, doublets and triplets. The extra symmetries needed to ensure the Dirac nature of neutrinos can also be responsible for stabilizing dark matter.

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arXiv2017

Can one ever prove that neutrinos are Dirac particles?

According to the "Black Box" theorem the experimental confirmation of neutrinoless double beta decay ($0 ν2 β$) would imply that at least one of the neutrinos is a Majorana particle. However, a null $0 ν2 β$ signal cannot decide the nature of neutrinos, as it can be suppressed even for Majorana neutrinos. In this letter we argue that if the null $0 ν2 β$ decay signal is accompanied by a $0 ν4 β$ quadruple beta decay signal, then at least one neutrino should be a Dirac particle. This argument holds irrespective of the underlying processes leading to such decays.

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arXiv2017

A Model of Comprehensive Unification

Comprehensive - that is, gauge and family - unification using spinors has many attractive features, but it has been challenged to explain chirality. Here, by combining an orbifold construction with more traditional ideas, we address that difficulty. Our candidate model features three chiral families and leads to an acceptable result for quantitative unification of couplings. A potential target for accelerator and astronomical searches emerges.

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arXiv2017

The Dark Side of Flipped Trinification

We propose a model which unifies the Left-Right symmetry with the $SU(3)_L$ gauge group, called flipped trinification, and based on the $SU(3)_C\otimes SU(3)_L\otimes SU(3)_R\otimes U(1)_X$ gauge group. The model inherits the interesting features of both symmetries while elegantly explaining the origin of the matter parity, $W_P=(-1)^{3(B-L)+2s}$, and dark matter stability. We develop the details of the spontaneous symmetry breaking mechanism in the model, determining the relevant mass eigenstates, and showing how neutrino masses are easily generated via the seesaw mechanism. Viable dark matter candidates can either be a fermion, a scalar or a vector, leading to potentially different dark matter phenomenology.

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arXiv2017

Predictive Pati-Salam theory of fermion masses and mixing

We propose a Pati-Salam extension of the standard model incorporating a flavor symmetry based on the $Δ\left( 27\right)$ group. The theory realizes a realistic Froggatt-Nielsen picture of quark mixing and a predictive pattern of neutrino oscillations. We find that, for normal neutrino mass ordering, the atmospheric angle must lie in the higher octant, CP must be violated in oscillations, and there is a lower bound for the $0νββ$ decay rate. For the case of inverted mass ordering, we find that the lower atmospheric octant is preferred, and that CP can be conserved in oscillations. Neutrino masses arise from a low-scale seesaw mechanism, whose messengers can be produced by a $Z^{\prime }$ portal at the LHC.

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arXiv2017

Heavy Higgs Boson Production at Colliders in the Singlet-Triplet Scotogenic Dark Matter Model

We consider the possibility that the dark matter particle is a scalar WIMP messenger associated to neutrino mass generation, made stable by the same symmetry responsible for the radiative origin of neutrino mass. We focus on some of the implications of this proposal as realized within the singlet-triplet scotogenic dark matter model.We identify consistent parameter sets consistent both with neutrino mass and the observed dark matter abundance. Finally we characterize the expected phenomenological profile of heavy Higgs boson physics at the LHC as well as at future linear Colliders.

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arXiv2017

Generalized Bottom-Tau unification, neutrino oscillations and dark matter: predictions from a lepton quarticity flavor approach

We propose an $A_4$ extension of the Standard Model with a Lepton Quarticity symmetry correlating dark matter stability with the Dirac nature of neutrinos. The flavor symmetry predicts (i) a generalized bottom-tau mass relation involving all families, (ii) small neutrino masses are induced a la seesaw, (iii) CP must be significantly violated in neutrino oscillations, (iv) the atmospheric angle $θ_{23}$ lies in the second octant, and (v) only the normal neutrino mass ordering is realized.

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arXiv2017

Three-family left-right symmetry with low-scale seesaw mechanism

We suggest a new left-right symmetric model implementing a low-scale seesaw mechanism in which quantum consistency requires three families of fermions. The symmetry breaking route to the Standard Model determines the profile of the "next" expected new physics, characterized either by the simplest left-right gauge symmetry or by the 3-3-1 scenario. The resulting $Z^\prime$ gauge bosons can be probed at the LHC and provide a production portal for the right-handed neutrinos. On the other hand, its flavor changing interactions would affect the K, D and B neutral meson systems.

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arXiv2017

Towards gauge coupling unification in left-right symmetric $\mathrm{SU(3)_c \times SU(3)_L \times SU(3)_R \times U(1)_{X}}$ theories

We consider the possibility of gauge coupling unification within the simplest realizations of the $\mathrm{SU(3)_c \times SU(3)_L \times SU(3)_R \times U(1)_{X}}$ gauge theory. We present a first exploration of the renormalization group equations governing the "bottom-up" evolution of the gauge couplings in a generic model with free normalization for the generators. Interestingly, we find that for a $\mathrm{SU(3)_c \times SU(3)_L \times SU(3)_R \times U(1)_{X}}$ symmetry breaking scale $M_X$ as low as a few TeV one can achieve unification in the presence of leptonic octets. We briefly comment on possible grand unified theory frameworks which can embed the $\mathrm{SU(3)_c \times SU(3)_L \times SU(3)_R \times U(1)_{X}}$ model as well as possible implications, such as lepton flavour violating physics at the LHC.

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arXiv2017

Unifying left-right symmetry and 331 electroweak theories

We propose a realistic theory based on the $\mathrm{SU(3)_c \otimes SU(3)_L \otimes SU(3)_R \otimes U(1)_{X}}$ gauge group which requires the number of families to match the number of colors. In the simplest realization neutrino masses arise from the canonical seesaw mechanism and their smallness correlates with the observed V-A nature of the weak force. Depending on the symmetry breaking path to the Standard Model one recovers either a left-right symmetric theory or one based on the $\mathrm{SU(3)_c \otimes SU(3)_L \otimes U(1)}$ symmetry as the "next" step towards new physics.

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arXiv2016

R-parity as a residual gauge symmetry : probing a theory of cosmological dark matter

We present a non-supersymmetric scenario in which the R-parity symmetry $R_P = (-1)^{3(B-L)+2s}$ arises as a result of spontaneous gauge symmetry breaking, leading to a viable Dirac fermion WIMP dark matter candidate. Direct detection in nuclear recoil experiments probes dark matter masses around $2-5$ TeV for $M_{Z^{\prime}} \sim 3-4$ TeV consistent with searches at the LHC, while lepton flavor violation rates and flavor changing neutral currents in neutral meson systems lie within reach of upcoming experiments.

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arXiv2016

Constraining Flavor Changing Interactions from LHC Run-2 Dilepton Bounds with Vector Mediators

Within the context of vector mediators, is a new signal observed in flavor changing interactions, particularly in the neutral mesons systems $K^{0}-\bar{K}^{0}$, $D^{0}-\bar{D}^{0}$ and $B^0-\bar{B^0}$, consistent with dilepton resonance searches at the LHC? In the attempt to address this very simple question, we discuss the complementarity between flavor changing neutral current (FCNC) and dilepton resonance searches at the LHC run 2 at $13$TeV with $3.2\, {\rm fb^{-1}}$ of integrated luminosity, in the context of vector mediators at tree level. Vector mediators, are often studied in the flavor changing framework, specially in the light of the recent LHCb anomaly observed at the rare B decay. However, the existence of stringent dilepton bound severely constrains flavor changing interactions, due to restrictive limits on the $Z^{\prime}$ mass. We discuss this interplay explicitly in the well motivated framework of a 3-3-1 scheme, where fermions and scalars are arranged in the fundamental representation of the weak SU(3) gauge group. Due to the paucity of relevant parameters, we conclude dilepton data leave little room for a possible new physics signal stemming from these systems, unless a very peculiar texture parametrization is used in the diagonalization of the CKM matrix. In other words, if a signal is observed in such flavor changing interactions, it is unlikely comes from a 3-3-1 model.

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arXiv2016

CP Violation from Flavor Symmetry in a Lepton Quarticity Dark Matter Model

We propose a simple $Δ(27) \otimes Z_4$ model where neutrinos are predicted to be Dirac fermions. The smallness of their masses follows from a type-I seesaw mechanism and the leptonic CP violating phase correlates with the pattern of $Δ(27)$ flavor symmetry breaking. The scheme naturally harbors a WIMP dark matter candidate associated to the Dirac nature of neutrinos, in that the same $Z_4$ lepton number symmetry also ensures dark matter stability.

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arXiv2016

Dirac Neutrinos and Dark Matter Stability from Lepton Quarticity

We propose to relate dark matter stability to the possible Dirac nature of neutrinos. The idea is illustrated in a simple scheme where small Dirac neutrino masses arise from a type--I seesaw mechanism as a result of a $Z_4$ discrete lepton number symmetry. The latter implies the existence of a viable WIMP dark matter candidate, whose stability arises from the same symmetry which ensures the Diracness of neutrinos.

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arXiv2016

Vacuum stability with spontaneous violation of lepton number

The vacuum of the Standard Model is known to be unstable for the measured values of the top and Higgs masses. Here we show how vacuum stability can be achieved naturally if lepton number is violated spontaneously at the TeV scale. More precise Higgs measurements in the next LHC run should provide a crucial test of our symmetry breaking scenario. In addition, these schemes typically lead to enhanced rates for processes involving lepton flavour violation .

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