F. de Campos - Unesp/Sao Jose dos Campos, Brazil

F. de Campos
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Name
F. de Campos
Affiliation
Unesp/Sao Jose dos Campos, Brazil
City
São José dos Campos
Country
Brazil

Pubs By Year

Pub Categories

 
High Energy Physics - Phenomenology (38)
 
Solar and Stellar Astrophysics (8)
 
Astrophysics of Galaxies (3)
 
High Energy Physics - Experiment (3)
 
Computer Science - Distributed; Parallel; and Cluster Computing (2)
 
Computer Science - Networking and Internet Architecture (2)
 
Cosmology and Nongalactic Astrophysics (1)
 
High Energy Astrophysical Phenomena (1)

Publications Authored By F. de Campos

We have obtained 53 images with the $g$ filter and 19 images with the $i$ filter, each with 600-second exposures of the super metal rich open cluster NGC 6253 with the Gemini-South telescope to create deep images of the cluster to observe the cluster white dwarfs for the first time. We will analyze the white dwarf luminosity function to measure the cluster's white dwarf age, search for any anomalous features (as has been seen in the similarly metal rich cluster NGC 6791), and constrain the initial-final mass relation at high metallicities. We present an update on these observations and our program to study the formation of white dwarfs in super high metallicity environments. Read More

OJ287 is a quasi-periodic quasar with roughly 12 year optical cycles. It displays prominent outbursts which are predictable in a binary black hole model. The model predicted a major optical outburst in December 2015. Read More

We report our study of features at the observed red end of the white dwarf cooling sequences for three Galactic globular clusters: NGC\,6397, 47\,Tucanae and M\,4. We use deep colour-magnitude diagrams constructed from archival Hubble Space Telescope (ACS) to systematically investigate the blue turn at faint magnitudes and the age determinations for each cluster. We find that the age difference between NGC\,6397 and 47\,Tuc is 1. Read More

We present a theoretical study on the metallicity dependence of the initial$-$to$-$final mass relation and its influence on white dwarf age determinations. We compute a grid of evolutionary sequences from the main sequence to $\sim 3\, 000$ K on the white dwarf cooling curve, passing through all intermediate stages. During the thermally-pulsing asymptotic giant branch no third dredge-up episodes are considered and thus the photospheric C/O ratio is below unity for sequences with metallicities larger than $Z=0. Read More

We present a simple approach for obtaining robust values of astrophysical parameters from the observed colour-magnitude diagrams (CMDs) of star clusters. The basic inputs are the Hess diagram built with the photometric measurements of a star cluster and a set of isochrones covering wide ranges of age and metallicity. In short, each isochrone is shifted in apparent distance modulus and colour excess until it crosses over the maximum possible Hess density. Read More

The vision of the Internet-of-Things (IoT) embodies the seam- less discovery, configuration, and interoperability of networked devices in various settings, ranging from home automation and multimedia to autonomous vehicles and manufacturing equipment. As these ap- plications become increasingly critical, the middleware coping with Machine-to-Machine (M2M) communication and coordination has to deal with fault tolerance and increasing complexity, while still abiding to resource constraints of target devices. In this report, we focus on configuration management and coordi- nation of services in a M2M scenario. Read More

The aim of this work is to explore the possibility to discover a fermionic field with mass dimension one, the Elko field, in the 14 TeV Large Hadron Collider (LHC), in processes with missing energy and one jet. We explore the possibility of a triple coupling with the Higgs field, generating also a contribution to the Elko mass term, and suggest some possibilities for future studies in this field. Read More

The Devices Profile for Web Services (DPWS) specification enables seamless discovery, configuration, and interoperability of networked devices in various settings, ranging from home automation and multimedia to manufacturing equipment and data centers. Unfortunately, the sheer simplicity of event notification mechanisms that makes it fit for resource-constrained devices, makes it hard to scale to large infrastructures with more stringent dependability requirements, ironically, where self-configuration would be most useful. In this report, we address this challenge with a proposal to integrate gossip-based dissemination in DPWS, thus maintaining compatibility with original assumptions of the specification, and avoiding a centralized configuration server or custom black-box middleware components. Read More

The aim of this work is to explore the possibility to discover a fermionic field with mass dimension one, the Elko field, in the Large Hadron Collider (LHC). Due to its mass dimension, an Elko can only interact either with Standard Model (SM) spinors and gauge fields at 1-loop order or at tree level through a quartic interaction with the Higgs field. In this Higgs portal scenario, the Elko is a viable candidate to a dark matter constituent which has been shown to be compatible with relic abundance measurements from WMAP and direct dark matter--nucleon searches. Read More

We present multichromatic isochrone fits to the colour-magnitude data of the globular cluster NGC 6366, based on Hubble Space Telescope Advanced Camera for Surveys/Wide Field Channel and Southern Astrophysical Research photometric data. We corrected the photometric data for differential reddening and calculated the mean ridge line of the colour-magnitude diagrams. We compared the isochrones of Dartmouth Stellar Evolution Database and PAdova and TRieste Stellar Evolution Code both with microscopic diffusion starting on the main sequence. Read More

We build differential-reddening maps for 66 Galactic globular clusters (GCs) with archival HST WFC/ACS F606W and F814W photometry. Because of the different GC sizes (characterised by the half-light radius $R_h$) and distances to the Sun, the WFC/ACS field of view ($200\arcsec\times200\arcsec$) coverage ($R_{obs}$) lies in the range $1\la R_{obs}/R_h\la15$ for about 85% of the sample, with about 10% covering only the inner ($R_{obs}\la R_h$) parts. We divide the WFC/ACS field of view across each cluster in a regular cell grid, and extract the stellar-density Hess diagram from each cell, shifting it in colour and magnitude along the reddening vector until matching the mean diagram. Read More

2013Jun
Affiliations: 1Unesp/Sao Jose dos Campos, Brazil, 2FSA - Santo Andre, Brazil

We consider minimal Gauge Mediated Supersymmetry Breaking models at which the next to lightest supersymmetric particle is a neutralino with a large enough decay length to be detected at the CERN Large Hadron Collider. We analyze the potential of the LHCb experiment to determine the discovery reach for such models and found that the LHCb will be able to probe such models up to the energy breaking scale of \Lambda = 130 TeV. Read More

We present panchromatic isochrone fits to the color magnitude data of the globular cluster NGC 6366, based on HST ACS/WFC and SOAR photometric data. Before performing the isochrone fits, we corrected the photometric data for differential reddening and calculated the mean ridge line of the color magnitude diagrams. We compared the isochrones of Dartmouth Stellar Evolution Database and PAdova and TRieste Stellar Evolution Code (with microscopic diffusion starting on the main sequence). Read More

Supersymmetric models with bilinear R-parity violation (BRPV) can account for the observed neutrino masses and mixing parameters indicated by neutrino oscillation data. We consider minimal supergravity versions of BRPV where the lightest supersymmetric particle (LSP) is a neutralino. This is unstable, with a large enough decay length to be detected at the CERN Large Hadron Collider (LHC). Read More

We study the prospects of observing the presence of a relatively light Elko particle as a possible dark matter candidate, by pointing out a typical signature for the process encompassing the Elko non-locality, exploring some consequences of the unusual Elko propagator behavior when analyzed outside the Elko axis of propagation. We also consider the production of a light Elko associated to missing energy and isolated leptons at the LHC, with center of mass energy of 7 and 14 TeV and total luminosity from $1 fb^{-1}$ to $10 fb^{-1}$. Basically, the Elko non locality engenders a peculiar signal in the missing energy turning it sensible to the angle of detection. Read More

The lightest supersymmetric particle may decay with branching ratios that correlate with neutrino oscillation parameters. In this case the CERN Large Hadron Collider (LHC) has the potential to probe the atmospheric neutrino mixing angle with sensitivity competitive to its low-energy determination by underground experiments. Under realistic detection assumptions, we identify the necessary conditions for the experiments at CERN's LHC to probe the simplest scenario for neutrino masses induced by minimal supergravity with bilinear R parity violation. Read More

The Large Hadron Collider presents an unprecedented opportunity to probe the realm of new physics in the TeV region and shed light on some of the core unresolved issues of particle physics. These include the nature of electroweak symmetry breaking, the origin of mass, the possible constituent of cold dark matter, new sources of CP violation needed to explain the baryon excess in the universe, the possible existence of extra gauge groups and extra matter, and importantly the path Nature chooses to resolve the hierarchy problem - is it supersymmetry or extra dimensions. Many models of new physics beyond the standard model contain a hidden sector which can be probed at the LHC. Read More

We explore the physics of crystallization in the deep interiors of white dwarf stars using the color-magnitude diagram and luminosity function constructed from proper motion cleaned Hubble Space Telescope photometry of the globular cluster NGC 6397. We demonstrate that the data are consistent with the theory of crystallization of the ions in the interior of white dwarf stars and provide the first empirical evidence that the phase transition is first order: latent heat is released in the process of crystallization as predicted by van Horn (1968). We outline how this data can be used to observationally constrain the value of Gamma = E_{Coulomb}/E_{thermal} near the onset of crystallization, the central carbon/oxygen abundance, and the importance of phase separation. Read More

2008Sep
Affiliations: 1Unesp, Guaratingueta, 2U. Sao Paulo, 3FSA, Santo Andre, 4U. de Antioquia, 5U. de Valencia, IFIC

The study of displaced vertices containing two b--jets may provide a double discovery at the Large Hadron Collider (LHC): we show how it may not only reveal evidence for supersymmetry, but also provide a way to uncover the Higgs boson necessary in the formulation of the electroweak theory in a large region of the parameter space. We quantify this explicitly using the simplest minimal supergravity model with bilinear breaking of R-parity, which accounts for the observed pattern of neutrino masses and mixings seen in neutrino oscillation experiments. Read More

Supersymmetric theories with bilinear R-parity violation can give rise to the observed neutrino masses and mixings. One important feature of such models is that the lightest supersymmetric particle might have a sufficiently large lifetime to give rise to detached vertices. Working in the framework of supergravity models we analyze the potential of the LHCb experiment to search for supersymmetric models exhibiting bilinear R-parity violation. Read More

We investigate a neutrino mass model in which the neutrino data is accounted for by bilinear R-parity violating supersymmetry with anomaly mediated supersymmetry breaking. We focus on the CERN Large Hadron Collider (LHC) phenomenology, studying the reach of generic supersymmetry search channels with leptons, missing energy and jets. A special feature of this model is the existence of long lived neutralinos and charginos which decay inside the detector leading to detached vertices. Read More

2008Jan

This review presents flavour related issues in the production and decays of heavy states at LHC, both from the experimental side and from the theoretical side. We review top quark physics and discuss flavour aspects of several extensions of the Standard Model, such as supersymmetry, little Higgs model or models with extra dimensions. This includes discovery aspects as well as measurement of several properties of these heavy states. Read More

We study the collider phenomenology of bilinear R-parity violating supergravity, the simplest effective model for supersymmetric neutrino masses accounting for the current neutrino oscillation data. At the CERN Large Hadron Collider the center-of-mass energy will be high enough to probe directly these models through the search for the superpartners of the Standard Model (SM) particles. We analyze the impact of R-parity violation on the canonical supersymmetry searches - that is, we examine how the decay of the lightest supersymmetric particle (LSP) via bilinear R-parity violating interactions degrades the average expected missing momentum of the reactions and show how this diminishes the reach in the 'usual' channels for supersymmetry searches. Read More

Supersymmetric extensions of the standard model exhibiting bilinear R-parity violation can generate naturally the observed neutrino mass spectrum as well mixings. One interesting feature of these scenarios is that the lightest supersymmetric particle (LSP) is unstable, with several of its decay properties predicted in terms of neutrino mixing angles. A smoking gun of this model in colliders is the presence of displaced vertices due to LSP decays in large parts of the parameter space. Read More

We show that a supersymmetric standard model exhibiting anomaly mediated supersymmetry breaking can generate naturally the observed neutrino mass spectrum as well mixings when we include bilinear R-parity violation interactions. In this model, one of the neutrinos gets its mass due to the tree level mixing with the neutralinos induced by the R-parity violating interactions while the other two neutrinos acquire their masses due to radiative corrections. One interesting feature of this scenario is that the lightest supersymmetric particle is unstable and its decay can be observed at high energy colliders, providing a falsifiable test of the model. Read More

We analyze the production of multileptons in the simplest supergravity model with bilinear violation of R parity at the Fermilab Tevatron. Despite the small R-parity violating couplings needed to generate the neutrino masses indicated by current atmospheric neutrino data, the lightest supersymmetric particle is unstable and can decay inside the detector. This leads to a phenomenology quite distinct from that of the R-parity conserving scenario. Read More

We analyze the low energy features of a supersymmetric standard model where the anomaly--induced contributions to the soft parameters are dominant in a scenario with bilinear $R$--parity violation. This class of models leads to mixings between the standard model particles and supersymmetric ones which change the low energy phenomenology and searches for supersymmetry. In addition, $R$--parity violation interactions give rise to small neutrino masses which we show to be consistent with the present observations. Read More

We present an outlook for possible discovery of supersymmetry with broken R-parity at Run II of the Tevatron. We first present a review of the literature and an update of the experimental bounds. In turn we then discuss the following processes: 1. Read More

We study unconventional decays of the top-quark and the top-squark in the framework of SUSY models with broken R-parity. The model under study is the MSSM with an additional bilinear term that breaks R-parity. In this model the top-squark behaves similar to a third generation leptoquark. Read More

We study the effects of new dimension--6 operators, resulting from a general $SU(3)_C \otimes SU(2)_L \otimes U(1)_Y$ invariant effective Lagrangian, on three jet production at LEP and at the Next Linear Collider. Contributions to the total event rate and to some event shape variables are analysed in order to establish bounds on these operators. Read More

1998Jun
Affiliations: 1DFQ/UNESP, Guaratingueta, Brazil, 2IFIC/CSIC, Valencia, Spain, 3IFT/UNESP, Sao Paulo, Brazil., 4IFT/UNESP, Sao Paulo, Brazil., 5IFT/UNESP, Sao Paulo, Brazil.

We derive bounds on Higgs and gauge--boson anomalous interactions using the CDF data for the process $p \bar{p} \to \gamma\gamma\gamma + X$. We use a linearly realized $SU_L(2) \times U_Y(1)$ invariant effective Lagrangian to describe the bosonic sector of the Standard Model, keeping the fermionic couplings unchanged. All dimension--six operators that lead to anomalous Higgs interactions involving $\gamma$ and $Z$ are considered. Read More

We study the pattern of gluino cascade decays in a class of supersymmetric models where R-parity is spontaneously broken. The multi-lepton and same-sign dilepton rates in these models are compared with those of the Minimal Supersymmetric Standard Model. We show that these rates can be substantially enhanced in models with broken R-parity. Read More

We study chargino pair production at LEP II in supersymmetric models with spontaneously broken R-parity. We perform signal and background analyses, showing that a large region of the parameter space of these models can be probed through chargino searches at LEP II. In particular, we determine the attainable limits on the chargino mass as a function of the magnitude of the effective bilinear R-parity violation parameter $\epsilon$, demonstrating that LEP II is able to unravel the existence of charginos with masses almost up to its kinematical limit even in the case of R-parity violation. Read More

1997Oct
Affiliations: 1Instituto de Fisica Teorica, Sao Paulo, Brazil., 2Instituto de Fisica Teorica, Sao Paulo, Brazil., 3Instituto de Fisica Teorica, Sao Paulo, Brazil., 4Instituto de Fisica Teorica, Sao Paulo, Brazil.

We present the sensitivity limits on the coefficients of a dimension-6 effective operators that parametrizes the possible effects of new physics beyond the Standard Model. Our results are based on the study of the processes $e^+ e^- \to W^+ W^- \gamma$, $Z Z\gamma$, and $Z\gamma \gamma$ at NLC energies. In our calculations, we include all the anomalous interactions involving vector and Higgs bosons, and take into account the Standard Model irreducible background. Read More

We estimate the attainable limits on the coefficients of dimension--6 operators from the analysis of Higgs boson phenomenology, in the framework of a $SU_L(2) \times U_Y(1)$ gauge-invariant effective Lagrangian. Our results, based on the data sample already collected by the collaborations at Fermilab Tevatron, show that the coefficients of Higgs-vector boson couplings can be determined with unprecedented accuracy. Assuming that the coefficients of all ``blind'' operators are of the same magnitude, we are also able to impose more restrictive bounds on the anomalous vector-boson triple couplings than the present limit from double gauge boson production at the Tevatron collider. Read More

We present sensitivity limits on the coefficients of a dimension-6 effective Lagrangian that parametrizes the possible effects of new physics beyond the Standard Model. Our results are based on the study of the process $e^+ e^- \to W^+ W^- \gamma$ at LEP2 and NLC energies. In our calculations, we include all the new anomalous interactions, involving vector and Higgs bosons, and take into account the Standard Model irreducible background. Read More

We study the pattern of gluino cascade decays in a class of supersymmetric models where R-parity is spontaneously broken. We give a detailed discussion of the R-parity violating decays of the lightest neutralino, the second lightest neutralino and the lightest chargino. The multi-lepton and same-sign dilepton signal rates expected in these models are compared with those predicted in the Minimal Supersymmetric Standard Model. Read More

We investigate the existence of anomalous Higgs boson couplings, $H\gamma\gamma$ and $HZ\gamma$, through the analysis of the process $e^+ e^- \to \gamma\gamma\gamma$ at LEP2 energies. We suggest some kinematical cuts to improve the signal to background ratio and determine the capability of LEP2 to impose bounds on those couplings by looking for a Higgs boson signal in this reaction. Read More

1996Apr
Affiliations: 1IST, Lisbon, 2IFT, Unesp, Brazil, 3IFIC, U. Valencia, 4IFIC, U. Valencia, 5IFIC, U. Valencia

We illustrate the sensitivities of LEP experiments to leptonic signals associated to models where supersymmetry (SUSY) is realized with spontaneous breaking of R-parity. We focus on missing transverse momentum plus acoplanar muon events arising from lightest neutralino single production $\chi \nu$ as well as pair production $\chi \chi$, followed by $\chi$ decays, where $\chi$ denotes the lightest neutralino. We show that the integrated luminosity achieved at LEP already starts probing the basic parameters of the theory. Read More

In this report we review the prospects for Higgs physics at LEP2. The theoretical aspects and the phenomenology of Higgs particles are discussed within the Standard Model (SM) and the Minimal Supersymmetric Standard Model (MSSM). The experimental search techniques are described and the discovery limits for Higgs bosons in the LEP2 energy range are summarized. Read More

We study the potential of LEP II to unravel the existence of invisibly decaying Higgs bosons, predicted in a wide class of models. We perform a model independent analysis, focusing our attention to the final state topologies exhibiting $b \bar{b}$ or $\ell^+ \ell^-$ ($\ell=\mu$ or $e$) pairs and missing energy. We carefully evaluate the signals and backgrounds, choosing appropriate cuts to enhance the discovery limits. Read More

We study the potential of LEP II to unravel the existence of invisibly decaying Higgs bosons through the reaction $e^+ e^- \rightarrow b\bar{b} + \ptmis$. We perform our analyses in a model independent way and our results show that LEP II is capable of discovering such a Higgs for a wide range of masses and couplings. Read More

R parity violation can induce mixing of the supersymmetric Higgs bosons with the sneutrinos at the tree level. We study the effect of this mixing on the decays of Higgs scalars as well as sneutrinos in an effective model where the violation of R parity is included in the minimal supersymmetric model through bilinear lepton number violating superpotential terms. We show that a small violation of R parity can lead to a sizeable branching ratio for the supersymmetric Higgs boson decay mode $H \to \chi \ell$ (where $\chi$ denotes an electroweak gaugino and $\ell$ is either a tau neutrino or a tau lepton). Read More

Many extensions of the standard electroweak model Higgs sector suggest that the main Higgs decay channel is "invisible", for example, $h \to J J$ where $J$ denotes the majoron, a weakly interacting pseudoscalar Goldstone boson associated to the spontaneous violation of lepton number. In many of these models the Higgs boson may also be produced in association to a massive pseudoscalar boson (HA), in addition to the standard Bjorken mechanism (HZ). We describe a general strategy to determine limits from LEP data on the masses and couplings of such Higgs bosons, using the existing data on acoplanar dijet events as well as data on four and six $b$ jet event topologies. Read More

Talk presented at the XXIX Rencontres de Moriond, Electroweak Interactions and Unified Theories, March 12-19, 1994, Meribel Read More

We show that the possibility of having light gluinos is not in conflict with recent LEP measurements and also that cosmology does not rule it out in any convincing way. In unified N=1 supergravity models, one expects that also the "photino" will be light. Moreover it leads to $upper$ limits on the masses of the other supersymmetric fermions, for example, the lightest chargino should be lighter than about 75 GeV, an thus detectable at LEP200. Read More

We derive model-independent constraints on Higgs mass and couplings from associated signals for higher masses, accessible at LEP2. This work is motivated by the fact that, in many extensions of the standard model, the Higgs boson can have substantial "invisible" decay modes, for example, into light or massless weakly interacting Goldstone bosons associated to the spontaneous violation of lepton number below the weak scale. Read More

Light gluinos have been suggested in order to reconcile $\alpha_s$ determinations from low energy deep inelastic experiments with those inferred from LEP measurements. {}From this hypothesis then one expects, in unified N=1 supergravity models, that also the "photino" will be light. We show that this possibility is not in conflict with recent LEP measurements and also that cosmology does not necessarily rule it out in any convincing way. Read More

The Higgs sector in spontaneously broken R Parity supersymmetry (RPSUSY) shows interesting features that require new search techniques. Both the mass spectrum and production rates may differ from the standard model and minimal supersymmetric model (MSSM) expectations. For some parameter choices, the dominant Higgs boson decay mode can even be invisible, leading to events with large missing transverse momentum carried by superweakly interacting majorons. Read More