A momentum Space Analysis of the Triple Pomeron Vertex in pQCD

We study properties of the momentum space Triple Pomeron Vertex in perturbative QCD. Particular attention is given to the collinear limit where transverse momenta on one side of the vertex are much larger than on the other side. We also comment on the kernels in nonlinear evolution equations.Comment: Minor misprints corrected. To be published in EPJ

Enhanced Molecular Orientation Induced by Molecular Anti-Alignment

We explore the role of laser induced anti-alignment in enhancing molecular orientation. A field-free enhanced orientation via anti-alignment scheme is presented, which combines a linearly polarized femtosecond laser pulse with a half-cycle pulse. The laser pulse induces transient anti-alignment in the plane orthogonal to the field polarization, while the half-cycle pulse leads to the orientation. We identify two qualitatively different enhancement mechanisms depending on the pulse order, and optimize their effects using classical and quantum models both at zero and non-zero temperature

Saturation Effects in Deep Inelastic Scattering at low Q2Q^2 and its Implications on Diffraction

We present a model based on the concept of saturation for small $Q^2$ and small $x$. With only three parameters we achieve a good description of all Deep Inelastic Scattering data below $x=0.01$. This includes a consistent treatment of charm and a successful extrapolation into the photoproduction regime. The same model leads to a roughly constant ratio of diffractive and inclusive cross section.Comment: 24 pages, 12 figures, Latex-fil

Active Flutter Suppression Using Reduced-Order Modeling for Transonic Aeroservoelastic Control Law Development

In this paper, several aerodynamic reduced-order models (ROMs) are generated and coupled with structural models to form aeroelastic ROMs. The aerodynamic ROMs generated here include the effects of control surface motion and are appropriate for use in aeroservoelastic applications. Simple observer-based full-state feedback controllers were designed from these aeroelastic ROMs. Additionally, observer gain matrices were designed from and coupled to the aeroelastic ROMs. Each (linear) observer was then used to estimate the dynamics of a (nonlinear) stand-alone computational fluid-structure dynamics simulation. Then, using the estimated states and the full-state feedback controller, control surface commands were fed back into the computational fluid-structure dynamics simulation to successfully achieve active flutter suppression. The process, as well as some results, are presented in this paper

Reduced Order Modeling for Transonic Aeroservoelastic Control Law Development

As aircraft become more flexible, aeroelastic considerations become increasingly important and complex, particularly for transonic flight where nonlinearities in the flow render linear analysis tools less effective. In order to analyze these aeroelastic interactions between the fluid and the structure efficiently, reduced order models (ROMs) are sometimes generated from and used in place of computational fluid dynamics solutions. In this paper, several aerodynamic ROMs are generated and coupled with structural models to form aeroelastic ROMs. The aerodynamic ROMs generated here include the effects of control surface motion. Hence, the aeroelastic ROMs presented here are appropriate for use in aeroservoelastic applications and are intended to be used for aeroservoelastic control law development. These ROMs are used to simulate a number of test cases with and without control surface involvement. Results show that several of the ROMs generated in the paper are able to predict results similar to solutions of higher-order computational methods

Geometric Scaling in Inclusive Charm Production

We show that the cross section for inclusive charm production exhibits geometric scaling in a large range of photon virtualities. In the HERA kinematic domain the saturation momentum $Q_{sat}^2(x)$ stays below the hard scale $\mu_c^2=4m_c^2$, implying charm production probing mostly the color transparency regime and unitarization effects being almost negligible. We derive our results considering two saturation models which are able to describe the DESY ep collider HERA data for the proton structure function at small values of the Bjorken variable $x$. A striking feature is the scaling on $\tau=Q_2^2/Q_{sat}^2(x)$ above saturation limit, corroborating recent theoretical studies.Comment: 4 pages, 2 figures. Version to be published in Physical Review Letter

Orienting coupled quantum rotors by ultrashort laser pulses

We point out that the non-adiabatic orientation of quantum rotors, produced by ultrashort laser pulses, is remarkably enhanced by introducing dipolar interaction between the rotors. This enhanced orientation of quantum rotors is in contrast with the behavior of classical paired rotors, in which dipolar interactions prevent the orientation of the rotors. We demonstrate also that a specially designed sequence of pulses can most efficiently enhances the orientation of quantum paired rotors.Comment: 7 pages, 5 figures, to appear in Phys. Rev.

Four point function of R-currents in N=4 SYM in the Regge limit at weak coupling

We compute, in N=4 super Yang-Mills theory, the four point correlation function of R-currents in the Regge limit in the leading logarithmic approximation at weak coupling. Such a correlator is the closest analog to photon-photon scattering within QCD, and there is a well-defined procedure to perform the analogous computation at strong coupling via the AdS/CFT correspondence. The main result of this paper is, on the gauge theory side, the proof of Regge factorization and the explicit computation of the R-current impact factors.Comment: 21 pages, 10 figures, typos correcte

Gluon multiplicity in coherent diffraction of onium on a heavy nucleus

We derive the cross section for the diffractive gluon production in high energy onium-nucleus collisions that includes the low-x evolution effects in the rapidity interval between the onium and the produced gluon and in the rapidity interval between the gluon and the target nucleus. We analyze our result in two limiting cases: when the onium size is much smaller than the saturation scale and when its size is much larger than the saturation scale. In the later case the gluon multiplicity is very small in the quasi-classical case and increases when the low-x evolution effects in onium become significant. We discuss the implications of our result for the RHIC, LHC and EIC phenomenology.Comment: 21 pages, 5 figure

Genetic and environmental covariation between autistic traits and behavioral problems

Objective: To examine the overlap between autistic traits and other behavioral problems in a general population sample, and explore the extent to which this overlap is due to genetic or environmental factors. Method: Youth Self Report (YSR) data were collected in a general population sample of 424 twin pairs at 18 years of age, and their non twin siblings. In 197 of these twin families, self-report ratings on the Autism-spectrum Quotient (AQ) were collected. Results: Stepwise backward regression analyses revealed that of all 8 YSR syndrome scales, the Withdrawn Behavior (WB) and Social Problems (SOC) scale were the most important predictors of AQ scores, and together with sex, explained 23% of the variance in AQ scores. Genetic structural equation modeling showed that the overlap between AQ and WB and SOC was mainly due to genetic effects. About half of the genetic variance in AQ scores was specific to the AQ, with the remaining half shared with genetic variance in WB and SOC. Conclusions: Endorsement of autistic traits in a general population sample is associated with social and withdrawn behavioral problems and these problems partly share a common genetic etiology with autistic traits. However, most of the variance in AQ scores remains unexplained by YSR scores, and half of the genetic variance in AQ is unshared with WB and SOC. These results indicate that autistic traits have specific characteristics that are substantially genetically independent from other common but related behavioral domains such as social problems and withdrawn behavior