NLO QCD corrections to WZ+jet production with leptonic decays

We compute the next-to-leading order QCD corrections to WZ+jet production at the Tevatron and the LHC, including decays of the electroweak bosons to light leptons with all off-shell effects taken into account. The corrections are sizable and have significant impact on the differential distributions.Comment: 14 pages, 7 figure

Radiation spectra of laser-driven quantum relativistic electrons

A procedure to calculate the radiation spectrum emitted by an arbitrarily prepared Dirac wave packet is developed. It is based on the Dirac charge current and classical electrodynamic theory. Apart from giving absolute intensity values, it is exact in terms of relativistic retardation effects and angular dependence. We employ a laser driven free electron to demonstrate the advantages of our method as compared to traditional ones that merely rely on the Fourier transform of the dipole operator's expectation value. Classical reference calculations confirm the results obtained for the low-frequency part of the spectrum, especially in terms of the observed red-shifts, which clearly deviate from non-relativistic calculations. In the high-frequency part of the spectrum, we note appreciable deviations to the purely classical calculations which may be linked to quantum averaging effects.Comment: 30 pages, 7 figure

Quasi‐2‐Day Wave in Low‐Latitude Atmospheric Winds as Viewed From the Ground and Space During January–March, 2020

Horizontal winds from four low-latitude (±15°) specular meteor radars (SMRs) and the Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) instrument on the ICON satellite, are combined to investigate quasi-2-day waves (Q2DWs) in early 2020. SMRs cover 80–100 km altitude whereas MIGHTI covers 95–300 km. Q2DWs are the largest dynamical feature of the summertime middle atmosphere. At the overlapping altitudes, comparisons between the derived Q2DWs exhibit excellent agreement. The SMR sensor array analyses show that the dominant zonal wavenumbers are s = +2 and + 3, and help resolve ambiguities in MIGHTI results. We present the first Q2DW depiction for s = +2 and s = +3 between 95 and 200 km, and show that their amplitudes are almost invariant between 80 and 100 km. Above 106 km, Q2DW amplitudes and phases present structures that might result from the superposition of Q2DWs and their aliased secondary waves

Spontaneous Magnetization of the O(3) Ferromagnet at Low Temperatures

We investigate the low-temperature behavior of ferromagnets with a spontaneously broken symmetry O(3) $\to$ O(2). The analysis is performed within the perspective of nonrelativistic effective Lagrangians, where the dynamics of the system is formulated in terms of Goldstone bosons. Unlike in a Lorentz-invariant framework (chiral perturbation theory), where loop graphs are suppressed by two powers of momentum, loops involving ferromagnetic spin waves are suppressed by three momentum powers. The leading coefficients of the low-temperature expansion for the partition function are calculated up to order $p^{10}$. In agreement with Dyson's pioneering microscopic analysis of the cubic ferromagnet, we find that, in the spontaneous magnetization, the magnon-magnon interaction starts manifesting itself only at order $T^4$. The striking difference with respect to the low-temperature properties of the O(3) antiferromagnet is discussed from a unified point of view, relying on the effective Lagrangian technique.Comment: 23 pages, 4 figure

Bright polar mesospheric clouds formed by main engine exhaust from the space shuttle's final launch

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94747/1/jgrd18009.pd

Online scheduling of bounded length jobs to maximize throughput

International audienceWe consider an online scheduling problem, motivated by the issues present at the joints of networks using ATM and TCP/IP. Namely, IP packets have to be broken down into small ATM cells and sent out before their deadlines, but cells corresponding to different packets can be interwoven. More formally, we consider the online scheduling problem with preemptions, where each job $j$ is revealed at release time $r_j$, and has processing time $p_j$, deadline $d_j$, and weight $w_j$. A preempted job can be resumed at any time. The goal is to maximize the total weight of all jobs completed on time. Our main results are as follows. Firstly, we prove that when the processing times of all jobs are at most $k$, the optimum deterministic competitive ratio is $\Theta(k /\log k)$. Secondly, we give a deterministic algorithm with competitive ratio depending on the ratio between the smallest and the largest processing time of all jobs. In particular, it attains competitive ratio 5 in the case when all jobs have identical processing times, for which we give a lower bound of 2.598. The latter upper bound also yields an $O(\log k)$-competitive randomized algorithm for the variant with processing times bounded by $k$