0000000000055593
AUTHOR
F. De Campos
Probing neutrino mass with displaced vertices at the Tevatron
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. In this work we focus on the simplest model of this type that comes from minimal supergravity with universal R-parity conserving soft breaking of supersymmetry (RmSUGRA). We evaluate the potentiality of the Fer…
Probing neutralino properties in minimal supergravity with bilinear R-parity violation
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). We analyse the LHC potential to determine the LSP properties, such as mass, lifetime and branching ratios, and discuss their relation to neutrino properties.
Finding the Higgs boson through supersymmetry
6 pages, 7 figures.-- PACS nrs.: 12.60.Jv; 13.85.Ni; 14.60.Pq; 14.80.Cp.-- ArXiv pre-print available at: http://arxiv.org/abs/0809.1637
Model independent Higgs boson mass limits at LEP
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.
Signatures of Spontaneous Breaking of R-Parity in Gluino Cascade Decays at LHC
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. We show that these rates can be substantially enhanced in broken R-parity models.
R-parity violating signals for chargino production at LEP II
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. This requires the study of several final state topologies since the usual MSSM chargino signature is reco…
Collider aspects of flavour physics at high Q
This chapter of the 'Flavor in the era of LHC' workshop report discusses flavor-related issues in the production and decays of heavy states at the LHC at high momentum transfer Q, both from the experimental and the theoretical perspective. We review top quark physics, and discuss the flavor aspects of several extensions of the standard model, such as supersymmetry, little Higgs models or models with extra dimensions. This includes discovery aspects, as well as the measurement of several properties of these heavy states. We also present publicly available computational tools related to this topic. © Springer-Verlag / Società Italiana di Fisica 2008.
Probing neutrino mass with multilepton production at the Tevatron in the simplest R-parity violation model
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. We quantify by how much the supersymmetric multilepton signals differ from the R-parity conserving expectations, displaying our results in the $m_0 \otimes m_{1/2}$ plane. We show that the presence of bilinear R-parity violating interactions enhances…
Probing bilinear R-parity violating supergravity at the LHC
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 re…
Novel Scalar Boson Decays in SUSY with Broken R-Parity
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). Relevant constraints on R parity violation as well as those coming from SUSY particle sear…
LEP sensitivities to spontaneous R-parity violating signals
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. We discuss the significance of these constraints for the simplest spontaneous R-parity breaking models and their relevance for future searches of SUSY particles.
Searching for Invisibly Decaying Higgs Bosons at LEP II
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. Our results demonstrate that LEP II is capable of discovering such a Higgs boson for a wide range of masses and couplings.
Detection of intermediate mass Higgs bosons from spontaneously broken R-parity supersymmetry
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. We study the reaction $pp \ra Z + H + X$, and find that it canlead to detectable events at LHC/SSC for a large region of parameter space.
The Hunt for New Physics at the Large Hadron Collider
233 páginas.-- AHEP Group: et al..-- El Pdf del artículo es la versión pre-print: arXiv.1001.2693v1.-- Trabajo presentado al "The International Workshop on Beyond the Standard Model Physics and LHC Signatures (BSM-LHC) celebrado en Boston (USA) del 2 al 4 de junio de 2009.
Limits on associated production of visibly and invisibly decaying Higgs bosons from Z decays
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. For the sake of illustrat…
Probing neutrino oscillations in supersymmetric models at the Large Hadron Collider
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.