Azimuthal-angle Observables in Inclusive Three-jet Production

We discuss the impact of corrections beyond the leading-logarithmic accuracy on some recently proposed LHC observables that are based on azimuthal-angle ratios in a kinematical setup that is an extension to the usual one for Mueller-Navelet jets, after requiring an extra tagged jet in central regions of rapidity. The corrections tend to be mild which suggests that these observables are an excellent way to probe the onset of BFKL effects at hadronic colliders.Comment: 6 pages, presented by G. Chachamis at the 25th International Workshop on Deep Inelastic Scattering and Related Topics, 3-7 April 2017, Birmingham, U

Inclusive Four-jet Production at 7 and 13 TeV: Azimuthal Profile in Multi-Regge Kinematics

Recently, new observables in LHC inclusive events with three tagged jets were proposed. Here, we extend that proposal to events with four tagged jets. The events are characterised by one jet in the forward direction, one in the backward direction with a large rapidity distance $Y$ from the first one and two more jets tagged in more central regions of the detector. In our setup, non-tagged associated mini-jet multiplicity is present and needs to be accounted for by the inclusion of BFKL gluon Green functions. The projection of the cross section on azimuthal-angle components opens up the opportunity for defining new ratios of correlation functions of the azimuthal angle differences among the tagged jets that can be used as probes of the BFKL dynamics.Comment: 19 pages, 8 figures; v2: published versio

Impacto do inseticida imidacloprido em aspectos biológicos de adultos de Mononychellus planki (McGregor) (Acari: Tetranychidae).

É amplamente conhecido o efeito deletério de agrotóxicos e de práticas de manejo cultural que prejudicam os inimigos naturais em campo e favorecem indiretamente os ácaros-praga em diferentes cultivos. Por outro lado, o efeito direto ou indireto de agrotóxicos na soja sobre ácaros fitófagos, favorecendo o seu desenvolvimento, precisa ser mais amplamente estudado. Tendo em vista a utilização de imidacloprido na cultura da soja em mistura comercial com um piretróide e a relação entre aumento na fecundidade de fêmeas de Tetranychus urticae Koch (Acari: Tetranychidae) com a utilização desse produto estudou-se a possibilidade deste mesmo princípio ativo causar efeito semelhante no ácaro verde Mononychellus planki. Foram testadas três formulações, Connect (100g i.a. imidacloprido/L de formulação + 12,5g i.a. beta-ciflutrina/L de formulação) e Provado 200SC (200g i.a. imidacloprido/L de formulação) e Kohinor 200SC (200g i.a. imidacloprido /L de formulação) em duas dosagens do ingrediente ativo imidacloprido, 0,013% e metade da dose (0,0065%). Ensaios com Bulldock 125 SC foram realizados para verificar a ação da beta-ciflutrina isoladamente, com dosagens de 100μL p.c./L (Diluição A) e 100μL p.c./L (Diluição B). Não foi observada diferença significativa na longevidade e fecundidade das fêmeas submetidas a ambas as dosagens de Connect, Kohinor e Provado; para aquelas tratadas com a diluição A de Bulldock 125SC observou-se longevidade e fecundidade média menor do que a obtida para testemunha. Entretanto a longevidade das fêmeas pulverizadas com a diluição B foi de 8,12 dias e fecundidade de 17,81 ovos/fêmea semelhantes às médias obtidas para a testemunha. Nos tratamentos com Connect, Kohinor e Provado constatou-se maior taxa de oviposição nos primeiros sete dias, consequentemente há possibilidade de estímulo ao aumento populacional de M. planki em campo após utilização de agrotóxicos com imidacloprido em sua composição

Lifetime Measurement of the 6s Level of Rubidium

We present a lifetime measurements of the 6s level of rubidium. We use a time-correlated single-photon counting technique on two different samples of rubidium atoms. A vapor cell with variable rubidium density and a sample of atoms confined and cooled in a magneto-optical trap. The 5P_{1/2} level serves as the resonant intermediate step for the two step excitation to the 6s level. We detect the decay of the 6s level through the cascade fluorescence of the 5P_{3/2} level at 780 nm. The two samples have different systematic effects, but we obtain consistent results that averaged give a lifetime of 45.57 +- 0.17 ns.Comment: 10 pages, 9 figure

A new look at the kinematics of the bulge from an N-body model

(Abridged) By using an N-body simulation of a bulge that was formed via a bar instability mechanism, we analyse the imprints of the initial (i.e. before bar formation) location of stars on the bulge kinematics, in particular on the heliocentric radial velocity distribution of bulge stars. Four different latitudes were considered: $b=-4^\circ$, $-6^\circ$, $-8^\circ$, and $-10^\circ$, along the bulge minor axis as well as outside it, at $l=\pm5^\circ$ and $l=\pm10^\circ$. The bulge X-shaped structure comprises stars that formed in the disk at different locations. Stars formed in the outer disk, beyond the end of the bar, which are part of the boxy peanut-bulge structure may show peaks in the velocity distributions at positive and negative heliocentric radial velocities with high absolute values that can be larger than 100 $\rm km$ $\rm s^{-1}$, depending on the observed direction. In some cases the structure of the velocity field is more complex and several peaks are observed. Stars formed in the inner disk, the most numerous, contribute predominantly to the X-shaped structure and present different kinematic characteristics. Our results may enable us to interpret the cold high-velocity peak observed in the APOGEE commissioning data, as well as the excess of high-velocity stars in the near and far arms of the X-shaped structure at $l$=$0^\circ$ and $b$=$-6^\circ$. When compared with real data, the kinematic picture becomes more complex due to the possible presence in the observed samples of classical bulge and/or thick disk stars. Overall, our results point to the existence of complex patterns and structures in the bulge velocity fields, which are generated by the bar. This suggests that caution should be used when interpreting the bulge kinematics: the presence of substructures, peaks and clumps in the velocity fields is not necessarily a sign of past accretion events.Comment: 21 pages, 18 figures. Accepted for publication in A&

Collapse and fragmentation of Gaussian barotropic protostellar clouds

We examine the problem of the collapse and fragmentation of molecular clouds with a Gaussian density distribution with high resolution, double precision numerical simulations using the GADGET-2 code. To describe the thermodynamic properties of the cloud during the collapse -to mimic the rise of temperature predicted by radiative transfer- we use a barotropic equation of state that introduces a critical density to separate the isothermal and adiabatic regimes. We discuss the effects of this critical density in the formation of multiple systems. We confirm the tendency found for Plummer and Gaussian models that if the collapse changes from isothermal to adiabatic at earlier times that occurs for the models with a lower critical density, the collapse is slowed down, and this enhances the fragments' change to survive. However, this effect happens up to a threshold density below which single systems tend to form. On the other hand, by setting a bigger initial perturbation amplitude, the collapse is faster and in some cases a final single object is formed.Comment: 8 pages, 4 figures, to appear in Experimental and Theoretical Advances in Fluid Dynamics, Springer Verlag (2011