Top A_FB at the Tevatron vs. charge asymmetry at the LHC in chiral U(1) flavor models with flavored Higgs doublets

We consider the top forward-backward (FB) asymmetry at the Tevatron and top charge asymmetry at the LHC within chiral U(1)^\prime models with flavor-dependent U(1)^\prime charges and flavored Higgs fields, which were introduced in the ref. [65]. The models could enhance not only the top forward-backward asymmetry at Tevatron, but also the top charge asymmetry at LHC, without too large same-sign top pair production rates. We identify parameter spaces for the U(1)^\prime gauge boson and (pseudo)scalar Higgs bosons where all the experimental data could be accommodated, including the case with about 125 GeV Higgs boson, as suggested recently by ATLAS and CMS.Comment: 11 pages, 6 figures, figures and discussion adde

A molecular dynamics study on the equilibrium magnetization properties and structure of ferrofluids

We investigate in detail the initial susceptibility, magnetization curves, and microstructure of ferrofluids in various concentration and particle dipole moment ranges by means of molecular dynamics simulations. We use the Ewald summation for the long-range dipolar interactions, take explicitly into account the translational and rotational degrees of freedom, coupled to a Langevin thermostat. When the dipolar interaction energy is comparable with the thermal energy, the simulation results on the magnetization properties agree with the theoretical predictions very well. For stronger dipolar couplings, however, we find systematic deviations from the theoretical curves. We analyze in detail the observed microstructure of the fluids under different conditions. The formation of clusters is found to enhance the magnetization at weak fields and thus leads to a larger initial susceptibility. The influence of the particle aggregation is isolated by studying ferro-solids, which consist of magnetic dipoles frozen in at random locations but which are free to rotate. Due to the artificial suppression of clusters in ferro-solids the observed susceptibility is considerably lowered when compared to ferrofluids.Comment: 33 pages including 12 figures, requires RevTex

Análise da estrutura fatorial da versão em português da Escala de Auto-Silenciamento

This study focuses on the adaptation of the Portuguese version of the Escala de Autosilenciamiento [EAS, for its Portuguese acronym] (Neves, 2005) that has been designed to assess the use of cognitive schemas for self silencing in intimate relationships. Participants were 371 women with a mean age of 22.36 years (SD=2.69; Min=18; Max=31), who at that time were involved in affective relationships with an average duration of 39.65 months (SD=33.93; Min=10; Max=192).The exploratory factor analysis suggests a factor solution of three factors, where the first factor includes items from the silencing of the sef and divided self subscales. The second factor includes items from the care-giving subscale such as self-sacrifice. And the third factor includes items from the externalized self-perception subscale. Results of the confirmatory factor analysis show reliable global indices of fitness of the model, confirming the quality of the model in terms of adjustment to empirical data (X2/df=1.964, CFI=.862, GFI=.894, RMSEA=.051) compared to the original model. Implications for a further study of the construct validity of the scale are discussed.Este estudo se centra na adaptação da versão em português da Escala de Auto-silenciamento (EAS; Neves, 2005) que está desenhada para avaliar o uso de esquemas cognitivos de auto-silenciamento nas relações íntimas. Neste estudo participaram 371 mulheres, com uma idade média de 22,36 anos (DP = 2,69, mín. = 18, máx. = 31), que nessa época estavam envolvidas em relações afetivas com uma duração média de 39,65 meses. (DP = 33,93, mín. = 0,10; máx. = 192). Uma análise fatorial exploratória posterior sugere uma solução de três fatores, aonde o primeiro fator inclui os itens da sub-escala de silenciamento do self e do self dividido; o segundo inclui os itens da sub-escala de Provisão de cuidados como o auto sacrifício, e o terceiro inclui os itens da sub-escala de auto percepção externalizada. Os resultados da análise fatorial confirmatória mostram índices gerais de adequação confiáveis, o que confirma a qualidade do ajuste do modelo aos dados empíricos (X2/df = 1964, CFI = .862, GFI = 0,894, RMSEA = 0,051) em comparação com a teste original. Analisam-se as implicações para um estudo más profundo da validez de constructo da escala.Este estudio se centra en la adaptación de la versión en portugués de la Escala de Autosilenciamiento (EAS; Neves, 2005) que está diseñada para evaluar el uso de esquemas cognitivos de autosilenciamiento en las relaciones íntimas. En este estudio participaron 371 mujeres, con una edad media de 22,36 años (DP = 2,69, mín. = 18, máx. = 31), que en esa época estaban involucradas en relaciones afectivas con una duración promedio de 39,65 meses. (DP = 33,93, mín. = 0,10; máx. = 192). Un análisis factorial exploratorio posterior sugiere una solución de tres factores, donde el primer factor incluye los ítems de la subescala de silenciamiento del self y del self dividido; el segundo incluye los ítems de la subescala de Provisión de cuidados como el autosacrificio, y el tercero incluye los ítems de la subescala de autopercepción externalizada. Los resultados del análisis factorial confirmatorio muestran índices generales de adecuación fiables, lo que confirma la calidad del ajuste del modelo a los datos empíricos (X2/df = 1964, CFI = .862, GFI = 0,894, RMSEA = 0,051) en comparación con la prueba original. Se analizan las implicaciones para un estudio más profundo de la validez de constructo de la escala

Operation and performance of the ATLAS semiconductor tracker

The semiconductor tracker is a silicon microstrip detector forming part of the inner tracking system of the ATLAS experiment at the LHC. The operation and performance of the semiconductor tracker during the first years of LHC running are described. More than 99% of the detector modules were operational during this period, with an average intrinsic hit efficiency of (99.74±0.04)%. The evolution of the noise occupancy is discussed, and measurements of the Lorentz angle, δ-ray production and energy loss presented. The alignment of the detector is found to be stable at the few-micron level over long periods of time. Radiation damage measurements, which include the evolution of detector leakage currents, are found to be consistent with predictions and are used in the verification of radiation background simulations

Search for H→γγ produced in association with top quarks and constraints on the Yukawa coupling between the top quark and the Higgs boson using data taken at 7 TeV and 8 TeV with the ATLAS detector

A search is performed for Higgs bosons produced in association with top quarks using the diphoton decay mode of the Higgs boson. Selection requirements are optimized separately for leptonic and fully hadronic final states from the top quark decays. The dataset used corresponds to an integrated luminosity of 4.5 fb−14.5 fb−1 of proton–proton collisions at a center-of-mass energy of 7 TeV and 20.3 fb−1 at 8 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. No significant excess over the background prediction is observed and upper limits are set on the tt¯H production cross section. The observed exclusion upper limit at 95% confidence level is 6.7 times the predicted Standard Model cross section value. In addition, limits are set on the strength of the Yukawa coupling between the top quark and the Higgs boson, taking into account the dependence of the tt¯H and tH cross sections as well as the H→γγ branching fraction on the Yukawa coupling. Lower and upper limits at 95% confidence level are set at −1.3 and +8.0 times the Yukawa coupling strength in the Standard Model

Fiducial and differential cross sections of Higgs boson production measured in the four-lepton decay channel in pp collisions at √s = 8 TeV with the ATLAS detector

Measurements of fiducial and differential cross sections of Higgs boson production in the H→ZZ∗ → 4ℓ decay channel are presented. The cross sections are determined within a fiducial phase space and corrected for detection efficiency and resolution effects. They are based on 20.3 fb−¹ of pp collision data, produced at √s = 8 TeV centre-of-mass energy at the LHC and recorded by the ATLAS detector. The differential measurements are performed in bins of transverse momentum and rapidity of the four-lepton system, the invariant mass of the subleading lepton pair and the decay angle of the leading lepton pair with respect to the beam line in the four-lepton rest frame, as well as the number of jets and the transverse momentum of the leading jet. The measured cross sections are compared to selected theoretical calculations of the Standard Model expectations. No significant deviation from any of the tested predictions is found

Search for W′→tb→qqbb decays in pp collisions at √s=8 TeV with the ATLAS detector

A search for a massive W′ gauge boson decaying to a top quark and a bottom quark is performed with the ATLAS detector in pp collisions at the LHC. The dataset was taken at a centre-of-mass energy of √s=8 TeV and corresponds to 20.3 fb−1 of integrated luminosity. This analysis is done in the hadronic decay mode of the top quark, where novel jet substructure techniques are used to identify jets from high-momentum top quarks. This allows for a search for high-mass W′ bosons in the range 1.5–3.0 TeV. b-tagging is used to identify jets originating from b-quarks. The data are consistent with Standard Model background-only expectations, and upper limits at 95 % confidence level are set on the W′→tb cross section times branching ratio ranging from 0.16pb to 0.33pb for left-handed W′ bosons, and ranging from 0.10pb to 0.21pb for W′ bosons with purely right-handed couplings. Upper limits at 95 % confidence level are set on the W′-boson coupling to tb as a function of the W′ mass using an effective field theory approach, which is independent of details of particular models predicting a W′boson