13,396 research outputs found

    On the connection of Gamma-rays, Dark Matter and Higgs searches at LHC

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    Motivated by the upcoming Higgs analyzes we investigate the importance of the complementarity of the Higgs boson chase on the low mass WIMP search in direct detection experiments and the gamma-ray emission from the Galactic Center measured by the Fermi-LAT telescope in the context of the SU(3)cSU(3)LU(1)NSU(3)_c\otimes SU(3)_L\otimes U(1)_N. We obtain the relic abundance, thermal cross section, the WIMP-nucleon cross section in the low mass regime and network them with the branching ratios of the Higgs boson in the model. We conclude that the Higgs boson search has a profound connection to the dark matter problem in our model, in particular for the case that (MWIMP<60M_{WIMP} < 60 GeV) the BR(H2H \rightarrow 2 WIMPs) 90\gtrsim 90%. This scenario could explain this plateau of any mild excess regarding the Higgs search as well as explain the gamma-ray emission from the galactic center through the bbˉb\bar{b} channel with a WIMP in the mass range of 25-45 GeV, while still being consistent with the current limits from XENON100 and CDMSII. However, if the recent modest excesses measured at LHC and TEVATRON are confirmed and consistent with a standard model Higgs boson this would imply that MWIMP>60 M_{WIMP} > 60 GeV, consequently ruling out any attempt to explain the Fermi-LAT observations.Comment: 8 pages, 9 figure

    Explaining ATLAS and CMS Results Within the Reduced Minimal 3-3-1 model

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    Recently the ATLAS and CMS collaborations announced the discovery of a higgs particle with a mass of 125\sim 125 GeV. The results are mildly consistent with the Standard Model Higgs boson. However, the combined data from these collaborations seem to point to an excess in the hγγh \rightarrow \gamma \gamma channel. In this work we analyze under which conditions this excess may be plausibly explained within the reduced minimal 3-3-1 model, while being consistent with bb, WW, ZZ and τ+τ\tau^+\tau^- channels. Moreover, we derive the properties of the heavy neutral and the doubly charged scalars predicted by the model. We then conclude that at a scale of a few TeV, this model provides a good fit to the ATLAS and CMS signal strength measurements, and therefore stands as an appealing alternative to the standard model.Comment: 23 pages, 9 figures. References adde

    Potencial alelopático de forrageiras tropicais: efeitos sobre invasoras de pastagens.

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    Extratos aquosos de sementes, parte aérea e raízes de três gramíneas e três leguminosas forrageiras foram preparados a uma concentração de 10%, com o objetivo de avaliar os efeitos potencialmente alelopáticos sobre a germinação de sementes e o alongamento da radícula das invasoras de pastagens: desmódio, guanxuma e as sa-pe ix e. A germinação foi monitorada em períodos de dez dias, com contagens diárias e eliminação das sementes germinadas. O alongamento da radícula era medido ao final de um período de dez dias de crescimento. Os efeitos do potencial osmótico foram isolados através de cálculos. As espécies doadoras evidenciaram potencialidades alelopáticas que variou de intensidade em função da especificidade entre espécies doadoras e receptoras. B. brizantha e calopogônio foram as espécies que promoveram as reduções mais intensas sobre a germinação das sementes e o alongamento da radícula das espécies receptoras. A parte aérea das espécies doadoras constituiu-se na principal fonte de substâncias potencialmente alelopáticas, solúveis em água. Independentemen te da espécie doadora, desmódio e guanxuma foram as invasoras que se mostraram mais susceptíveis aos efeitos potencialmente alelopáticos, enquanto o assa-peixe foi a mais tolerante

    Combining type I and type II seesaw mechanisms in the minimal 3-3-1 model

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    The minimal 3-3-1 model is perturbative until energies around 4-5TeV, posing a challenge to generate neutrino masses at eV scale, mainly if one aims to take advantage of the seesaw mechanism. As a means to circumvent this problem we propose a modification of the model such that it accommodates the type I and type II seesaw mechanisms altogether. We show that the conjunction of both mechanisms yield a neutrino mass expression suppressed by a high power of the cutoff scale, M5M^5, in its denominator. With such a suppression term we naturally obtain neutrino masses at eV scale when MM is around few TeV. We also investigate the size of lepton flavor violation through the process μeγ\mu \rightarrow e\gamma.Comment: about 15 pages, no figure

    Observing Grasping Actions Directed to Emotion-Laden Objects: Effects upon Corticospinal Excitability

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    The motor system is recruited whenever one executes an action as well as when one observes the same action being executed by others. Although it is well established that emotion modulates the motor system, the effect of observing other individuals acting in an emotional context is particularly elusive. The main aim of this study was to investigate the effect induced by the observation of grasping directed to emotion-laden objects upon corticospinal excitability (CSE). Participants classified video-clips depicting the right-hand of an actor grasping emotion-laden objects. Twenty video-clips differing in terms of valence but balanced in arousal level were selected. Motor evoked potentials (MEPs) were then recorded from the first dorsal interosseous using transcranial magnetic stimulation (TMS) while the participants observed the selected emotional video-clips. During the video-clip presentation, TMS pulses were randomly applied at one of two different time points of grasping: (1) maximum grip aperture, and (2) object contact time. CSE was higher during the observation of grasping directed to unpleasant objects compared to pleasant ones. These results indicate that when someone observes an action of grasping directed to emotion-laden objects, the effect of the object valence promotes a specific modulation over the motor system.Fil: Nogueira Campos, Anaelli A.. Universidade Federal de Juiz de Fora; BrasilFil: Saunier, Ghislain. Universidade Federal do Pará; BrasilFil: Della Maggiore, Valeria Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: De Oliveira, Laura A. S.. Centro Universitário Augusto Motta; BrasilFil: Rodrigues, Erika C.. Centro Universitário Augusto Motta; BrasilFil: Vargas, Claudia D.. Universidade Federal do Rio de Janeiro; Brasi

    Ancilla-based quantum simulation

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    We consider simulating the BCS Hamiltonian, a model of low temperature superconductivity, on a quantum computer. In particular we consider conducting the simulation on the qubus quantum computer, which uses a continuous variable ancilla to generate interactions between qubits. We demonstrate an O(N^3) improvement over previous work conducted on an NMR computer [PRL 89 057904 (2002) & PRL 97 050504 (2006)] for the nearest neighbour and completely general cases. We then go on to show methods to minimise the number of operations needed per time step using the qubus in three cases; a completely general case, a case of exponentially decaying interactions and the case of fixed range interactions. We make these results controlled on an ancilla qubit so that we can apply the phase estimation algorithm, and hence show that when N \geq 5, our qubus simulation requires significantly less operations that a similar simulation conducted on an NMR computer.Comment: 20 pages, 10 figures: V2 added section on phase estimation and performing controlled unitaries, V3 corrected minor typo
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