Busca por ressonâncias de grávitons em modelos com dimensões extras no LHC

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Áxions, májorons e neutrinos em extensões do modelo padrão

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A estrutura do nucleon na QCD e o modelo estatístico a Quarks

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Busca por dimensões extras no detector CMS do large hadron collider

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

Comments on correlation functions of large spin operators and null polygonal Wilson loops

We discuss the relation between correlation functions of twist-two large spin operators and expectation values of Wilson loops along light-like trajectories. After presenting some heuristic field theoretical arguments suggesting this relation, we compute the divergent part of the correlator in the limit of large 't Hooft coupling and large spins, using a semi-classical world-sheet which asymptotically looks like a GKP rotating string. We show this diverges as expected from the expectation value of a null Wilson loop, namely, as (ln mu(-2))(2). mu being a cut-off of the theory. (C) 2012 Elsevier B.V. All rights reserved.

Vacuum polarization by a magnetic flux in a cosmic string background.

In this paper we analyse the vacuum polarization effects due to a magnetic flux on massless fermionic fields in a cosmic string background. Three distinct configurations of magnetic fields are considered. In all of them the magnetic fluxes are confined in a long cylindrical tube of finite radius.

RNS derivation of N-point disk amplitudes from the revisited S-matrix approach

Recently, in [7] we proposed a revisited S-matrix approach to efficiently find the bosonic terms of the open superstring low energy effective lagrangian (OSLEEL). This approach allows to compute the alpha'(N) terms of the OSLEEL using open superstring n-point amplitudes in which n is considerably lower than (N + 2) (which is the order of the required amplitude to obtain those alpha'(N) terms by means of the conventional S-matrix approach). In this work we use our revisited S-matrix approach to examine the structure of the scattering amplitudes, arriving at a closed form for them. This is a RNS derivation of the formula first found by Mafra, Schlotterer and Stieberger [21], using the pure spinor formalism. We have succeeded doing this for the 5, 6 and 7-point amplitudes. In order to achieve these results we have done a careful analysis of the kinematical structure of the amplitudes, finding as a by-product a purely kinematical derivation of the BCJ relations (for N = 4, 5, 6 and 7). Also, following the spirit of the revisited S-matrix approach, we have found the alpha' expansions for these amplitudes up to alpha'(6) order in some cases, by only using the well known open superstring 4-point amplitude, cyclic symmetry and tree level unitarity: we have not needed to compute any numerical series or any integral involving polylogarithms, at any moment. (C) 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/).

Comparison of Nonmesonic Hypernuclear Decay Rates Computed in Laboratory and Center-of-Mass Coordinates

In this work we compute the one-nucleon-induced nonmesonic hypernuclear decay rates of He-5(Lambda), C-12(Lambda) and C-13(Lambda) using a formalism based on the independent particle shell model in terms of laboratory coordinates. To ascertain the correctness and precision of the method, these results are compared with those obtained using a formalism in terms of center-of-mass coordinates, which has been previously reported in the literature. The formalism in terms of laboratory coordinates will be useful in the shell-model approach to two-nucleon-induced transitions.

Confecção e caracterização de filmes finos de boro para a medida da taxa de reação 10B(N, a)7LI na terapia por captura de nêutrons pelo boro

The Boron Neutron Capture Therapy (BNCT), based on the 10B(n,α)7Li reaction, represents a promising modality for the treatment of cancers that are resistents to conventional treatments. So, it is necessary to find drugs (boron compounds) with high selectivity for each type of cancer, the neutrons source should be well characterized and the rate of 10B(n,α)7Li reaction should be measured with great accuracy as possible. This study aimed to develop a method for manufacturing thin films of boron, for measure the 10B(n,α)7Li reaction, and analyze the uniformity of the films. Five thin films of boron were manufactured with three different concentrations of boric acid, heated to transform the acid in boron, irradiated with thermic neutrons coupled to CR-39 detectors, in BNCT line at the reactor IEA-R1 IPEN/CNEN, São Paulo. After the irradiation, the detectors were chemically attacked with NaOH to reveal the tracks. The methodology presented is effective because it resulted in deposition of boron as thin film enabling the quantitative analysis of 10B(n,α)7Li reaction. The analysis of the uniformity of density of the induced tracks in CR-39 shows that, in most of the films, there is no uniformity in surface distribution of boron, but when the film is divided, we obtain some uniform sectors

Produção de partículas secundárias em reações de “spallation” induzidas por prótons

Cosmic radiation has been identi ed as one of the main hazard to crew, aircraft and sensitive equipments involved in long-term missions and even high-altitude commercial ights. Generally, shields are used in spatial units to avoid excessive exposure, by holding the incident radiation. Unfortunatelly, shielding in space is problematic, especially when high-energy cosmic particles are considered, due to the production of large number of secondary particles, mainly neutrons, protons and alpha particles, caused by spallation reactions and quasi-elastic processes of the corpuscular radiation with the shield. Good parameters for checking the secondary particle production at target material are diferential cross section and energy deposited in the shield. Addition experiments, some computer codes based on Monte Carlo method show themselves a suitable tool to calculate shield parameters, due to have evaluated nuclear data libraries implemented on the algorithm. In view of this, the aim of this work is determining the parameters evaluated in shielding materials, by using MCNPX code, who shows good agreement with experimental data from literature. Among the materials, Aluminium had lower emission and production of secondary particles

O bóson de Higgs no modelo padrão das interações eletrofracas: aspectos fenomenológicos do setor escalar e resultados experimentais

Pós-graduação em Física - FEG

Pulsating strings from two-dimensional CFT on (T-4)(N)/S(N)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Transmission coefficient and two-fold degenerate discrete spectrum of spin-1 bosons in a double-step potential

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Bose-Einstein correlation measurements at CMS

Multidimensional and one-dimensional quantum-statistical (Bose-Einstein) correlations are measured in proton proton collisions at 0.9, 2.76 and 7 TeV, in proton lead collisions at 5.02 TeV/nucleon pair and peripheral lead lead collisions at 2.76 TeV/nucleon pair center-of-mass energy with the CMS detector at the LHC. The correlation functions are extracted in terms of different components of the relative momentum of the pair, in order to investigate the extension of the emission source in different directions. The results are presented for different intervals of transverse pair momentum, k(T), and charged particle multiplicity of the collision, N-tracks, as well as for their integrated values. Besides inclusive charged particles, charged pions and kaons, identified via their energy loss in the silicon tracker detector, can also be correlated. The extracted source radii increase with increasing multiplicity, and decrease with increasing k(T). The results open the possibility to study scaling and factorization properties of these radii as a function of multiplicity, k(T), colliding system size and center-of-mass energy.

Nonmesonic weak decay dynamics from proton spectra of Lambda-hypernuclei

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