Recent development in parton shower multijet merging

Higher order calculations are necessary to predict and describe measurements in high energy collider physics. In recent years multiple approaches to combine multiple next-to-leading (NLO) order corrections with parton showers had been presented. We present on recent developments and future perspective. We highlight similarities and ambiguities in the procedure of achieving a multijet merging at NLO.Comment: 7 pages, 3 figures, DIS16 proceeding

Colour Rearrangement for Dipole Showers

We present an algorithm to rearrange the colour chains of dipole showers in the shower process according to the colour amplitudes of a simple matrix element. We implement the procedure in the dipole shower of Herwig and show comparisons to data.Comment: 4 pages, 6 figures, HERWIG-2018-01, LU-TP-18-01, MCnet-18-0

The unblinking eye on the sky

From near-Earth asteroids to superluminous supernovae and counterparts to gravitational wave sources, the Zwicky Transient Facility will soon scan the night sky for transient phenomena.Comment: Author's version of "Mission Control" profile published in Nature Astronomy. 3 pages, 1 figure. https://www.nature.com/articles/s41550-017-007

Volumetric Survey Speed: A Figure of Merit for Transient Surveys

Time-domain surveys can exchange sky coverage for revisit frequency, complicating the comparison of their relative capabilities. By using different revisit intervals, a specific camera may execute surveys optimized for discovery of different classes of transient objects. We propose a new figure of merit, the instantaneous volumetric survey speed, for evaluating transient surveys. This metric defines the trade between cadence interval and snapshot survey volume and so provides a natural means of comparing survey capability. The related metric of areal survey speed imposes a constraint on the range of possible revisit times: we show that many modern time-domain surveys are limited by the amount of fresh sky available each night. We introduce the concept of "spectroscopic accessibility" and discuss its importance for transient science goals requiring followup observing. We present an extension of the control time algorithm for cases where multiple consecutive detections are required. Finally, we explore how survey speed and choice of cadence interval determine the detection rate of transients in the peak absolute magnitude–decay timescale phase space

An unusual pi* shape resonance in the near-threshold photoionization of S(1) para-difluorobenzene

Previously reported dramatic changes in photoelectron angular distributions (PADs) as a function of photoelectron kinetic energy following the ionization of S1 p-difluorobenzene are shown to be explained by a shape resonance in the b(2g) symmetry continuum. The characteristics of this resonance are clearly demonstrated by a theoretical multiple-scattering treatment of the photoionization dynamics. New experimental data are presented which demonstrate an apparent insensitivity of the PADs to both vibrational motion and prepared molecular alignment, however, the calculations suggest that strong alignment effects may nevertheless be recognized in the detail of the comparison with experimental data. The apparent, but unexpected, indifference to vibrational excitation is rationalized by considering the nature of the resonance. The correlation of this shape resonance in the continuum with a virtual pi* antibonding orbital is considered. Because this orbital is characteristic of the benzene ring, the existence of similar resonances in related substituted benzenes is discussed.Bellm, SM: Davies, JA: Whiteside, PT; Guo, J: Powis, I; and Reid KL