Search results

Radiative lifetimes of 17 high-lying excited states in Rh I aremeasured using the time-resolved laser-induced fluorescence method. Out of these lifetimes, 13 are new and the remaining four confirm previous measurements. Furthermore, we report the first theoretical investigation of Rh I, where the radiative decay properties of all experimentally known levels below 47 000 cm(-1) are calculated using

The concept of multiple partonic interactions in hadronic events is vital for the understanding of both minimum-bias and underlying-event physics. The area is rather little studied, however, and current models off er a far from complete coverage, even of the effects we know ought to be there. In this article we address one such topic, namely that of rescattering, where an already scattered parton

We present a method to match the multi-parton states generated by the High Energy Jets Monte Carlo with parton showers generated by the A riadne program using the colour dipole model. The High Energy Jets program already includes a full resummation of soft divergences. Hence, in the matching it is important that the corresponding divergences in the parton shower are subtracted, keeping only the co

We have measured the oscillator strength of the Ni I line at 6300.34Å, which is known to be blended with the forbidden line [O I]lambda6300 used for the determination of the oxygen abundance in coolstars. We also give wavelengths of the two isotopic line components of⁵⁸Ni and ⁶⁰Ni derived from the asymmetriclaboratory line profile. These two line components of Ni I have to be

We propose a sophisticated framework for high-energy hadronic collisions, wherein different QCD physics processes are interleaved in a common sequence of falling transverse-momentum values. Thereby phase-space competition is introduced between multiple parton-parton interactions and initial-state radiation. As a first step we develop new transverse-momentum-ordered showers for initial- and final-s

Multi-peaked spectra of the primordial gravitational waves are considered as a phenomenologically relevant source of information about the dynamics of sequential phase transitions in the early Universe. In particular, such signatures trace back to specific patterns of the first-order electroweak phase transition in the early Universe occurring in multiple steps. Such phenomena appear to be rather

Hanbury Brown-Twiss interferometry (HBT) provides crucial insights into both the space-time structure and the momentum-space evolution of ultrarelativistic nuclear collisions at freeze-out. In particular, the dependence of the HBT radii on the transverse pair momentum KT and the system charged multiplicity dNch/dη may reflect the mechanisms driving collective behavior in small systems. This paper

The process ${⤪ e}^{+}{⤪ e}^{-}⌝ghtarrow {⤪ W}^{+}{⤪ W}^{-}⌝ghtarrow {⤪ f}_{1}{⩈erline {⤪ f}}_{2}{⤪ f}_{3}{⩈erline {⤪ f}}_{4}$ contains charges in the initial, intermediate and final stages. This gives a rich selection of possible QED interconnection effects. Coulomb interaction is the simplest of these, and can thus be used to explore consequences. We study a number of experimental observables, w

Given the current landscape in experimental high-energy physics, these lectures are focused on applications of event generators for hadron colliders such as the Tevatron and LHC. Much of this would also be relevant for e+e−machines like LEP, ILC and CLIC, or e±p machines like HERA, but with some differences not discussed here. Heavy-ion physics is not addressed, since it involves rather different as

We derive short-distance constraints for the hadronic light-by-light contribution (HLbL) to the anomalous magnetic moment of the muon in the kinematic region where the three virtual momenta are all large. We include the external soft photon via an external field leading to a well-defined Operator Product Expansion. We establish that the perturbative quark loop gives the leading contribution in a w

We present a trinification-based grand unified theory incorporating a global SU(3)F family symmetry, that after spontaneous symmetry breaking leads to a left-right symmetric model. In addition to unification of gauge couplings, the model unifies Yukawa interactions and contains equivalent representations in the scalar and fermion sectors at high energy scales. Considering the minimal low-energy sc

At the LHC all processes are QCD ones, whether 'signal' or 'background'. In this review the frontiers of current QCD research are addressed, towards increased understanding, improved calculational precision, and role in potential future discoveries. Issues raised include: the limits of perturbative QCD calculations and parton distribution usage, the nature of multiparton interactions, the impact o

We present a new framework for modeling hard diffractive events in photoproduction, implemented in the general purpose event generator Pythia 8. The model is an extension of the model for hard diffraction with dynamical gap survival in p p and p p ¯ collisions proposed in 2015, now also allowing for other beam types. It thus relies on several existing ideas: the Ingelman–Schlein approach, the fra

The Large Hadron Electron Collider (LHeC) project is the proposal to use the existing LHC proton/ion beams and construct a new electron beam line to perform high-energy electron-proton/ion collisions. In this talk, we consider some of the physics topics that could be studied in the electronion mode. In particular, we estimate how much the current nuclear parton distribution fits could be improved

The statistical models used to derive the results of experimental analyses are of incredible scientific value and are essential information for analysis preservation and reuse. In this paper, we make the scientific case for systematically publishing the full statistical models and discuss the technical developments that make this practical. By means of a variety of physics cases - including parton

The Astropy Project supports and fosters the development of open-source and openly developed Python packages that provide commonly needed functionality to the astronomical community. A key element of the Astropy Project is the core package astropy, which serves as the foundation for more specialized projects and packages. In this article, we summarize key features in the core package as of the rec

In this article, we study the fully differential observables of the exclusive production of heavy (charm and bottom) quark pairs in high-energy ultraperipheral pA and AA collisions. In these processes, the nucleus A serves as an efficient source of the photon flux, while the QCD interaction of the produced heavy-quark pair with the target (p or A) proceeds via an exchange of gluons in a color sing

Aims. We aim to measure lifetimes of levels belonging to the 3d 3 ( 4 F)4d subconfiguration in Va II, and derive absolute transition probabilities by combining the lifetimes with experimental branching fractions. Methods. The lifetimes were measured using time-resolved laser-induced fluorescence in a two-photon excitation scheme. The branching fractions were measured in intensity calibrated spe

We present a parton-level phenomenological study of triple-Higgs production at leading order in proton-proton collisions at a center-of-mass energy of 100 TeV with an integrated luminosity of 30 ab^-1. This study aims to estimate the prospects for measuring the signal hhh production observable at the Future Circular Collider. We explore interesting final states that could be used for this purpose