Search for massive resonances decaying into pairs of boosted bosons in semi-leptonic final states at root s=8 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Complex scalar dark matter in a B-L model

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Soluções do tipo vórtice em um modelo de Maxwell-Chern-Simons-Higgs com campos de Gauge distintos

Pós-graduação em Física - FEG

New physics from warped compact extra dimensions: from model building to colliders signals

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Search for long-lived particles that decay into final states containing two electrons or two muons in proton-proton collisions at root s=8Tev

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Dirac gaugions, R symmetry and the 125 GeV Higgs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Light-by-light scattering with intact protons at the LHC: from standard model to new physics

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Colorless top partners, a 125 GeV Higgs boson, and the limits on naturalness

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Search for heavy neutrinos and W bosons with right-handed couplings in proton-proton collisions at root s=8TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Radiative Omega(-)->Xi(-)gamma decay and physics beyond the standard model

We investigate the impact of new physics beyond the standard model to the s → dγ process, which is responsible for the short-distance contribution to the radiative decay Ω-Ξ-γ. We study three representative extensions of the standard model: namely, a one-family technicolor model, a two-Higgs-doublet model, and a model containing scalar leptoquarks. When constraints arising from the observed b→sγ transition and the upper limit on D0-D̄0 mixing are taken into account, we find no significant contributions of new physics to the s→dy process.

Anomalous Higgs boson contribution to e(+)e(-)->b(b)over-bar gamma at CERN LEP 2

We study the effect of anomalous Hγγ and HZγ couplings, described by a general effective Lagrangian, on the process e+e-→bb̄γ at CERN LEP 2 energies. We include the relevant irreducible standard model background to this process, and from the photon energy spectrum, we determine the reach of LEP 2 to unravel the anomalous couplings by analyzing the significance of the signal for a Higgs boson with a mass up to 150 GeV.

Soluções tipo vórtex em teorias de gauge Chern-Simons-Maxwell-Higgs

Pós-graduação em Física - IFT

Quantum critical scaling at a Bose-glass/superfluid transition: Theory and experiment for a model quantum magnet

In this paper we investigate the quantum phase transition from magnetic Bose Glass to magnetic Bose-Einstein condensation induced by amagnetic field in NiCl2 center dot 4SC(NH2)(2) (dichloro-tetrakis-thiourea-nickel, or DTN), doped with Br (Br-DTN) or site diluted. Quantum Monte Carlo simulations for the quantum phase transition of the model Hamiltonian for Br-DTN, as well as for site-diluted DTN, are consistent with conventional scaling at the quantum critical point and with a critical exponent z verifying the prediction z = d; moreover the correlation length exponent is found to be nu = 0.75(10), and the order parameter exponent to be beta = 0.95(10). We investigate the low-temperature thermodynamics at the quantum critical field of Br-DTN both numerically and experimentally, and extract the power-law behavior of the magnetization and of the specific heat. Our results for the exponents of the power laws, as well as previous results for the scaling of the critical temperature to magnetic ordering with the applied field, are incompatible with the conventional crossover-scaling Ansatz proposed by Fisher et al. [Phys. Rev. B 40, 546 (1989)]. However they can all be reconciled within a phenomenological Ansatz in the presence of a dangerously irrelevant operator.

Search for the MSSM Neutral Higgs Boson in the mu+mu- final state with the CMS experiment at LHC

In this thesis, my work in the Compact Muon Solenoid (CMS) experiment on the search for the neutral Minimal Supersymmetric Standard Model (MSSM) Higgs decaying into two muons is presented. The search is performed on the full data collected during the years 2011 and 2012 by CMS in proton-proton collisions at CERN Large Hadron Collider (LHC). The MSSM is explored within the most conservative benchmark scenario, m_h^{max}, and within its modified versions, m_h^{mod +} and m_h^{mod -}. The search is sensitive to MSSM Higgs boson production in association with a b\bar{b} quark pair and to the gluon-gluon fusion process. In the m_h^{max} scenario, the results exclude values of tanB larger than 15 in the m_A range 115-200 GeV, and values of tanB greater than 30 in the m_A range up to 300 GeV. There are no significant differences in the results obtained within the three different scenarios considered. Comparisons with other neutral MSSM Higgs searches are shown.

Interacting bosons and fermions in three-dimensional optical lattice potentials

This thesis reports on the realization, characterization and analysis of ultracold bosonic and fermionic atoms in three-dimensional optical lattice potentials. Ultracold quantum gases in optical lattices can be regarded as ideal model systems to investigate quantum many-body physics. In this work interacting ensembles of bosonic 87Rb and fermionic 40K atoms are employed to study equilibrium phases and nonequilibrium dynamics. The investigations are enabled by a versatile experimental setup, whose core feature is a blue-detuned optical lattice that is combined with Feshbach resonances and a red-detuned dipole trap to allow for independent control of tunneling, interactions and external confinement. The Fermi-Hubbard model, which plays a central role in the theoretical description of strongly correlated electrons, is experimentally realized by loading interacting fermionic spin mixtures into the optical lattice. Using phase-contrast imaging the in-situ size of the atomic density distribution is measured, which allows to extract the global compressibility of the many-body state as a function of interaction and external confinement. Thereby, metallic and insulating phases are clearly identified. At strongly repulsive interaction, a vanishing compressibility and suppression of doubly occupied lattice sites signal the emergence of a fermionic Mott insulator. In a second series of experiments interaction effects in bosonic lattice quantum gases are analyzed. Typically, interactions between microscopic particles are described as two-body interactions. As such they are also contained in the single-band Bose-Hubbard model. However, our measurements demonstrate the presence of multi-body interactions that effectively emerge via virtual transitions of atoms to higher lattice bands. These findings are enabled by the development of a novel atom optical measurement technique: In quantum phase revival spectroscopy periodic collapse and revival dynamics of the bosonic matter wave field are induced. The frequencies of the dynamics are directly related to the on-site interaction energies of atomic Fock states and can be read out with high precision. The third part of this work deals with mixtures of bosons and fermions in optical lattices, in which the interspecies interactions are accurately controlled by means of a Feshbach resonance. Studies of the equilibrium phases show that the bosonic superfluid to Mott insulator transition is shifted towards lower lattice depths when bosons and fermions interact attractively. This observation is further analyzed by applying quantum phase revival spectroscopy to few-body systems consisting of a single fermion and a coherent bosonic field on individual lattice sites. In addition to the direct measurement of Bose-Fermi interaction energies, Bose-Bose interactions are proven to be modified by the presence of a fermion. This renormalization of bosonic interaction energies can explain the shift of the Mott insulator transition. The experiments of this thesis lay important foundations for future studies of quantum magnetism with fermionic spin mixtures as well as for the realization of complex quantum phases with Bose-Fermi mixtures. They furthermore point towards physics that reaches beyond the single-band Hubbard model.