arXiv subjects

Farinaldo S. Queiroz

Publications and source records attributed to Farinaldo S. Queiroz.

At least 91 records · Page 5Linked to original sources

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

Left-Right Symmetry and Lepton Number Violation at the Large Hadron Electron Collider

We show that the proposed Large Hadron electron Collider (LHeC) will provide an opportunity to search for left-right symmetry and establish lepton number violation, complementing current and planned searches based on LHC data and neutrinoless double beta decay. We consider several plausible configurations for the LHeC -- including different electron energies and polarizations, as well as distinct values for the charge misidentification rate. Within left-right symmetric theories we determine the values of right-handed neutrino and gauge boson masses that could be tested at the LHeC after one, five and ten years of operation. Our results indicate that this collider might probe, via the $ΔL =2$ signal $e^-p\to e^+jjj$, Majorana neutrino masses up to 1 TeV and $W_R$ masses up to 6.5 TeV. Interestingly, part of this parameter space is beyond the expected reach of the LHC and of future neutrinoless double beta decay experiments.

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arXiv2016

Dark Matter and Global Symmetries

General considerations in general relativity and quantum mechanics are known to potentially rule out continuous global symmetries in the context of any consistent theory of quantum gravity. Assuming the validity of such considerations, we derive stringent bounds from gamma-ray, X-ray, cosmic-ray, neutrino, and CMB data on models that invoke global symmetries to stabilize the dark matter particle. We compute up-to-date, robust model-independent limits on the dark matter lifetime for a variety of Planck-scale suppressed dimension-five effective operators. We then specialize our analysis and apply our bounds to specific models including the Two-Higgs-Doublet, Left-Right, Singlet Fermionic, Zee-Babu, 3-3-1 and Radiative See-Saw models. {Assuming that (i) global symmetries are broken at the Planck scale, that (ii) the non-renormalizable operators mediating dark matter decay have $O(1)$ couplings, that (iii) the dark matter is a singlet field, and that (iv) the dark matter density distribution is well described by a NFW profile}, we are able to rule out fermionic, vector, and scalar dark matter candidates across a broad mass range (keV-TeV), including the WIMP regime.

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arXiv2016

Dilepton bounds on left-right symmetry at the LHC run II and neutrinoless double beta decay

In the light of the new 13 TeV dilepton data set with $ 3.2\, {\rm fb^{-1}}$ integrated luminosity from the ATLAS collaboration, we derive limits on the $Z^{\prime}$ mass in the context of left-right symmetric models and exploit the complementarity with dijet and $lljj$ data, as well as neutrinoless double beta decay. We keep the ratio of the left- and right-handed gauge coupling free in order to take into account different patterns of left-right symmetry breaking. By combining the dielectron and dimuon data we can exclude $Z^{\prime}$ masses below $3$ TeV for $g_R=g_L$, and for $g_R \sim 1$ we rule out masses up to $\sim 4$ TeV. Those comprise the strongest direct bounds on the $Z^{\prime}$ mass from left-right models up to date. We show that in the usual plane of right-handed neutrino and charged gauge boson mass, dilepton data can probe a region of parameter space inaccessible to neutrinoless double beta decay and $lljj$ studies. Lastly, through the mass relation between $W_R$ and $Z^{\prime}$ we present an indirect bound on the lifetime of neutrinoless double beta decay using dilepton data. Our results prove that the often ignored dilepton data in the context of left-right models actually provide important complementary limits.

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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

Is the dark matter particle its own antiparticle?

We propose a test based on direct detection data that allows to determine if the dark matter particle is different from its antiparticle. The test requires the precise measurement of the dark matter spin-independent direct detection cross sections off $\mathrm{three}$ different nuclei, and consists of interpreting such signals in terms of self-conjugate (particle $=$ antiparticle) dark matter to see if such interpretation is consistent. If it is not, the dark matter must be different from its antiparticle. We illustrate this procedure for two sets of target nuclei, $\mathrm{\{Xe, Ar, Si\}}$ and $\mathrm{\{Xe, Ar, Ge\}}$, identifying the regions of the parameter space where it is particularly feasible. Our results indicate that future signals in direct detection experiments, if sufficiently accurate, might be used to establish that the dark matter particle is not its own antiparticle --a major step towards the determination of the fundamental nature of the dark matter.

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arXiv2016

NLO+NLL Collider Bounds, Dirac Fermion and Scalar Dark Matter in the B-L Model

Baryon and lepton numbers being accidental global symmetries of the Standard Model (SM), it is natural to promote them to local symmetries. However, to preserve anomaly freedom, only combinations of B-L are viable. In this spirit, we investigate possible dark matter realizations in the context of the $U(1)_{B-L}$ model: (i) Dirac fermion with unbroken B-L; (ii) Dirac fermion with broken B-L; (iii) scalar dark matter; (iv) two component dark matter. We compute the relic abundance, direct and indirect detection observables and confront them with recent results from Planck, LUX-2016, and Fermi-LAT and prospects from XENON1T. In addition to the well known LEP bound $M_{Z^{\prime}}/g_{BL} \gtrsim 7$ TeV, we include often ignored LHC bounds using 13 TeV dilepton (dimuon+dielectron) data at next-to-leading order plus next-to-leading logarithmic accuracy. We show that, for gauge couplings smaller than $0.4$, the LHC gives rise to the strongest collider limit. In particular, we find $M_{Z^{\prime}}/g_{BL} > 8.7$ TeV for $g_{BL}=0.3$. We conclude that the NLO+NLL corrections improve the dilepton bounds on the $Z^{\prime}$ mass and that both dark matter candidates are only viable in the $Z^{\prime}$ resonance region, with the parameter space for scalar dark matter being fully probed by XENON1T. Lastly, we show that one can successfully have a minimal two component dark matter model.

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arXiv2016

Gamma-ray Limits on Neutrino Lines

MMonochromatic neutrinos from dark matter annihilations ($χχ\to ν\barν$) are always produced in association with a gamma-ray spectrum generated by electroweak bremsstrahlung. Consequently, these neutrino lines can be searched for not only with neutrino detectors but also indirectly with gamma-ray telescopes. Here, we derive limits on the dark matter annihilation cross section into neutrinos based on recent Fermi-LAT and HESS data. We find that, for dark matter masses above 200 GeV, gamma-ray data actually set the most stringent constraints on neutrino lines from dark matter annihilation and, therefore, an upper bound on the dark matter total annihilation cross section. In addition, we point out that gamma-ray telescopes, unlike neutrino detectors, have the potential to distinguish the flavor of the final state neutrino. Our results indicate that we have already entered into a new era where gamma-ray telescopes are more sensitive than neutrino detectors to neutrino lines from dark matter annihilation.

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arXiv2016

Extending Fermi-LAT and H.E.S.S. Limits on Gamma-ray Lines from Dark Matter Annihilation

Gamma-ray lines from dark matter annihilation ($χχ\to γX$, where $X=γ,h,Z$) are always accompanied, at lower energies, by a continuum gamma-ray spectrum stemming both from radiative corrections ($X=γ$) and from the decay debris of the second particle possibly present in the final state ($X=h,Z$). This model-independent gamma-ray emission can be exploited to derive novel limits on gamma-ray lines that do not rely on the line-feature. Although such limits are not expected to be as stringent, they can be used to probe the existence of $γ$-ray lines for dark matter masses beyond the largest energies accessible to current telescopes. Here, we use continuous gamma-ray searches from Fermi-LAT observations of Milky Way dwarf spheroidal galaxies and from H.E.S.S. observations of the Galactic Halo to extend the limits on the annihilation cross sections into monochromatic photons to dark matter masses well beyond $500$ GeV (Fermi-LAT) and $20$ TeV (H.E.S.S.). In this large mass regime, our results provide the first constraints on $γ$-ray lines from dark matter annihilation.

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arXiv2016

Collider and Dark Matter Searches in the Inert Doublet Model from Peccei-Quinn Symmetry

Weakly Interacting Massive Particles (WIMPs) and axions are arguably the most compelling dark matter candidates in the literature. Could they coexist as dark matter particles? More importantly, can they be incorporated in a well motivated framework in agreement with experimental data? In this work, we show that this two component dark matter can be realized in the Inert Doublet Model in an elegant and natural manner by virtue of the spontaneous breaking of a Peccei-Quinn $U(1)_{PQ}$ symmetry into a residual $Z_2$ symmetry. The WIMP stability is guaranteed by the $Z_{2}$ symmetry and a new dark matter component, the axion, arises. There are two interesting outcomes: (i) vector-like quarks needed to implement the Peccei-Quinn symmetry in the model act as a portal between the dark sector and the SM fields with a supersymmetry-type phenomenology at colliders; (ii) two-component Inert Doublet Model re-opens the phenomenologically interesting 100-500 GeV mass region. We show that the model can plausibly have two component dark matter and at the same time avoid low and high energy physics constraints such as monojet and dijet plus missing energy, as well as indirect and direct dark matter detection bounds.

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arXiv2016

Dark Matter Overview: Collider, Direct and Indirect Detection Searches

The complementarity of direct, indirect and collider searches for dark matter has improved our understanding concerning the properties of the dark matter particle. I will review the basic concepts that these methods rely upon and highlight what are the most important information they provide when it comes down to interpret the results in terms of Weakly Interacting Massive Particles (WIMPs). Later, I go over some of the latest results emphasizing the implications to dark matter theory in a broad sense and point out recent developments and prospects in the field.

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arXiv2016

New Limits on the Dark Matter Lifetime from Dwarf Spheroidal Galaxies using Fermi-LAT

Dwarf spheroidal galaxies (dSphs) are promising targets for the indirect detection of dark matter through gamma-ray emission due to their proximity, lack of astrophysical backgrounds and high dark matter density. They are often used to place restrictive bounds on the dark matter annihilation cross section. In this paper, we analyze six years of {\it Fermi}-LAT gamma-ray data from 19 dSphs that are satellites of the Milky Way, and derive from a stacked analysis of 15 dSphs, robust 95\% confidence level lower limits on the dark matter lifetime for several decay channels and dark matter masses between $\sim 1$GeV and $10$TeV. Our findings are based on a bin-by-bin maximum likelihood analysis treating the J-factor as a nuisance parameter using PASS 8 event-class. Our constraints from this ensemble are among the most stringent and solid in the literature, and competitive with existing ones coming from the extragalactic gamma-ray background, galaxy clusters, AMS-02 cosmic ray data, Super-K and ICECUBE neutrino data, while rather insensitive to systematic uncertainties. In particular, among gamma-ray searches, we improve existing limits for dark matter decaying into $\bar{b}b$, ($μ^+μ^-$) for DM masses below $\sim 30\, (200)$~GeV, demonstrating that dSphs are compelling targets for constraining dark matter decay lifetimes.

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arXiv2016

The CTA aims at the Inert Doublet Model

We show that the Cherenkov Telescope Array (CTA) can realistically challenge the Inert Doublet Model, excluding its heavy regime up to dark matter masses of 800 GeV and probing a large fraction of the remaining viable parameter space at even higher masses. Two features of the Inert Doublet Model make it particularly suitable for CTA searches. First, the dark matter mass (in the heavy regime) must be larger than 500 GeV. Second, the dark matter annihilation cross section, $σv$, is always larger than the thermal one, reaching values as high as $10^{-25} \mathrm{cm^3s^{-1}}$. This higher value of $σv$ is the result of the unavoidable coannhilation effects that determine the relic density via thermal freeze-out in the early Universe. We find that with 100 hours of Galactic Center exposure, CTA's expected limit widely surpasses, even after the inclusion of systematic errors, current and projected bounds from Fermi-LAT and HESS on this model.

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arXiv2015

Stringent Dilepton Bounds on Left-Right Models using LHC data

In canonical left-right symmetric models the lower mass bounds on the charged gauge bosons are in the ballpark of $3-4$ TeV, resulting into much stronger limits on the neutral gauge boson $Z_R$, making its production unreachable at the LHC. However, if one evokes different patterns of left-right symmetry breaking the $Z_R$ might be lighter than the $W_R^\pm$ motivating an independent $Z_R$ collider study. In this work, we use the 8 TeV ATLAS $20.3$ fb$^{-1}$ luminosity data to derive robust bounds on the $Z_R$ mass using dilepton data. %because they provide the most restrictive limits due to the sizable $Z_R$-lepton couplings. We find strong lower bounds on the $Z_R$ mass for different right-handed gauge couplings, excluding $Z_R$ masses up to $\sim 3.2$TeV. For the canonical LR model we place a lower mass bound of $\sim 2.5$TeV. Our findings are almost independent of the right-handed neutrino masses ($\sim 2\,\%$ effect) and applicable to general left-right models.

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arXiv2015

Dirac-Fermionic Dark Matter in $U(1)_X$ Models

We study a number of $U(1)_X$ models featuring a Dirac fermion dark matter particle. We perform a comprehensive analysis which includes the study of corrections to the muon magnetic moment, dilepton searches with LHC data, as well as direct and indirect dark matter detection constraints. We consider four different coupling structures, namely $U(1)_{B-L}, U(1)_{d-u}, U(1)_{universal}$, and $U(1)_{10+\bar{5}}$, all motivated by compelling extensions to the standard model. We outline the viable and excluded regions of parameter space using a large set of probes. Our key findings are that (i) the combination of direct detection and collider constraints rule out dark matter particle masses lighter than $\sim 1$ TeV, unless rather suppressed Z'-fermion couplings exist, and that (ii) for several of the models under consideration, collider constraints rule out Z' masses up to $\sim 3$ TeV. Lastly, we show that we can accommodate the recent Diboson excess reported by ATLAS collaboration within the $U(1)_{d-u}$ model.

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arXiv2015

Dark Matter Complementarity and the Z$^\prime$ Portal

Z' gauge bosons arise in many particle physics models as mediators between the dark and visible sectors. We exploit dark matter complementarity and derive stringent and robust collider, direct and indirect constraints, as well as limits from the muon magnetic moment. We rule out almost the entire region of the parameter space that yields the right dark matter thermal relic abundance, using a generic parametrization of the Z'-fermion couplings normalized to the Standard Model Z-fermion couplings for dark matter masses in the 8 GeV-5 TeV range. We conclude that mediators lighter than 2.1 TeV are excluded regardless of the DM mass, and that depending on the Z'-fermion coupling strength much heavier masses are needed to reproduce the DM thermal relic abundance while avoiding existing limits.

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arXiv2015

Interpreting the CMS $\ell^+\ell^- jj E\!\!\!\!/_{\rm T}$ Excess with a Leptoquark Model

Motivated by excesses in $ee jj$ and $eνjj$ channels observed by the CMS collaboration, in 8 TeV LHC data, a model of lepto-quarks with mass around 500 GeV was proposed in the literature. In order to reproduce the claimed event rate, lepto-quarks were assumed to have a significant partial branching ratio into an extra sector, taken to be Dark Matter, other than the canonical $ej$. We here show that the decay channel of lepto-quark into Dark Matter can fit another excess claimed by CMS, in $\ell^+\ell^- jj E\!\!\!\!/_{\rm T}$: the event rate, the distribution in di-lepton invariant mass and the rapidity range are compatible with the data. We provide predictions for the forthcoming Run II of the 14 TeV LHC and discuss aspects of dark matter detection.

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arXiv2014

Dark Matter from Late Invisible Decays to/of Gravitinos

In this work, we sift a simple supersymmetric framework of late invisible decays to/of the gravitino. We investigate two cases where the gravitino is the lightest supersymmetric particle or the next-to-lightest supersymmetric particle. The next-to-lightest supersymmetric particle decays into two dark matter candidates and has a long lifetime due to gravitationally suppressed interactions. However, because of the absence of any hadronic or electromagnetic products, it satisfies the tight bounds set by big bang nucleosynthesis and cosmic microwaved background. One or both of the dark matter candidates produced in invisible decays can contribute to the amount of dark radiation and suppress perturbations at scales that are being probed by the galaxy power spectrum and the Lyman-alpha forest data. We show that these constraints are satisfied in large regions of the parameter space and, as a result, the late invisible decays to/of the gravitino can be responsible for the entire dark matter relic abundance.

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