Correlations in the azimuthal angle between the two largest transverse momentum jets have been measured using the D0 detector in p (-)p collisions at a center-of-mass energy sqrt[s]=1.96 TeV. The analysis is based on an inclusive dijet event sample in the central rapidity region corresponding to an integrated luminosity of 150 pb(-1). Azimuthal correlations are stronger at larger transverse momenta. These are well described in perturbative QCD at next-to-leading order in the strong coupling constant, except at large azimuthal differences where contributions with low transverse momentum are significant.
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http://dx.doi.org/10.1103/PhysRevLett.94.221801 | DOI Listing |
A scalar, harmonic beam-like field possessing an arbitrary number of orbital angular momentum (OAM) components is shown to trace an ellipse, termed here the orbitalization ellipse, at a given transverse cross section and radius, in the space spanned by the spiral OAM basis. The plane and the structure of the ellipse can be readily found by constructing its conjugate semi-diameter vectors from the OAM components.
View Article and Find Full Text PDFSci Adv
January 2025
Center for Nano Science and Technology, Fondazione Istituto Italiano di Tecnologia, Milano, Italy.
Achieving highly tailored control over both the spatial and temporal evolution of light's orbital angular momentum (OAM) on ultrafast timescales remains a critical challenge in photonics. Here, we introduce a method to modulate the OAM of light on a femtosecond scale by engineering a space-time coupling in ultrashort pulses. By linking azimuthal position with time, we implement an azimuthally varying Fourier transformation to dynamically alter light's spatial distribution in a fixed transverse plane.
View Article and Find Full Text PDFJ Chem Phys
January 2025
CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China.
While most thermostats in molecular dynamics are designed for equilibrium systems, their extension to non-equilibrium simulations has little theoretical justification. In the literature, an artifact referred to as "lane formation" was discovered; however, its cause remained unclear and was simply attributed to a constraint on velocity fluctuations or non-ergodicity in thermostats. In addition, global deterministic thermostatted dynamics was found to exhibit unceasing phase-space compression in steady states, incompatible with their expected stationary distributions and Gibbs entropy, which was mistakenly perceived as inescapable.
View Article and Find Full Text PDFLight Sci Appl
January 2025
Department of Physics, Chalmers University of Technology, 412 96, Gothenburg, Sweden.
Nanostructured dielectric metasurfaces offer unprecedented opportunities to control light-matter momentum exchange, and thereby the forces and torques that light can exert on matter. Here we introduce optical metasurfaces as components of ultracompact untethered microscopic metaspinners capable of efficient light-induced rotation in a liquid environment. Illuminated by weakly focused light, a metaspinner generates torque via photon recoil through the metasurfaces' ability to bend light towards high angles despite their sub-wavelength thickness, thereby creating orbital angular momentum.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
CERN, Geneva, Switzerland.
High-energy nuclear collisions create a quark-gluon plasma, whose initial condition and subsequent expansion vary from event to event, impacting the distribution of the eventwise average transverse momentum [P([p_{T}])]. Disentangling the contributions from fluctuations in the nuclear overlap size (geometrical component) and other sources at a fixed size (intrinsic component) remains a challenge. This problem is addressed by measuring the mean, variance, and skewness of P([p_{T}]) in ^{208}Pb+^{208}Pb and ^{129}Xe+^{129}Xe collisions at sqrt[s_{NN}]=5.
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