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In this very special solstice episode of The Meridian Nic and Rebecca look back at some of the highlights of 2021. With the days growing ever longer here in the Northern Hemisphere they have rallied a troupe of PhD students to compete in the 2021 Astronomy Games! Nic is joined by Alvaro and Johan on his team and Rebecca has convinced Daniel and Madeleine to join her team. The Games were recorded i
In the second episode of the second season Nic and Rebecca invite Diane Feuillet to the microphone. Diane is a researcher here at Lund Observatory working on galactic archaeology using stellar abundances, ages and kinematics. In this second season of the Meridian we are also bringing you some field reporting from the Nordic Optical Telescope on La Palma, where a team of astronomers are trying to c
We study a random surface representation of Wilson loops in Z(2) gauge theory. The weights consist of an area factor, which dominates at strong coupling, and an excluded volume factor flavouring crumpled surfaces. We examine the latter one in some detail in three as well as four dimensions by use of Monte Carlo methods. In three dimensions, the critical behaviour of the surfaces is found to be det
We claim that experimental meson spectroscopy now requires the existence of constituent gluons. Drawing from several models, we study the number of mesons with given quantum numbers that can be expected in a given mass range, concentrating on pseudoscalars below 2 GeV. Counting only quark-antiquark states gives fewer mesons than are now seen, but including gluon degrees of freedom so that glueball
We show how to obtain a "heavy" meson effective lagrangian for the case where the number of heavy particles is not conserved. We apply the method in a simple example at tree level and perform then the reduction for the case of vector mesons in Chiral Perturbation Theory in a manifestly chiral invariant fashion. Some examples showing that "heavy" meson effective theory also reproduces the correct n
In the hadroproduction of charm in the context of string fragmentation, the pull of a beam remnant at the other end of a string may give a charm hadron more energy than the perturbatively produced charm quark. The collapse of a low-mass string to a single hadron is the extreme case in this direction, and gives rise to asymmetries between charm and anticharm hadron spectra. We study these phenomena
We discuss single diffractive gauge bosons (γ*, W±, Z) production in proton-proton collisions at LHC energy (14 TeV) in the framework of the color dipole approach. The calculations are performed for gauge bosons produced at forward rapidities. The diffractive cross section is predicted as a function of fractional momentum and invariant mass of the lepton pair. We found a dramatic breakdown of the
We present the scattering lengths for the pi-pi processes in the three flavour Chiral Perturbation Theory (ChPT) framework at next-to-next-to-leading order. We then combine this calculation with the determination of the parameters from $Ke4 and the masses and decay constants and compare with the results of a dispersive analysis of pi-pi scattering. The comparison indicates a small but nonzero valu
The vector and axial-vector two-point functions are calculated to next-to-next-to-leading order in Chiral Perturbation Theory for three light flavours. We also obtain expressions at the same order for the masses, m2 π, m2 Κ and m2 η, and the decay constants, Fπ, FΚ and Fη. We present some numerical results after a simple resonance estimate of some of the new O(p6) constants.
This article is over 5 years old, and the information may therefore be outdated. The Ravensbrück archive at the University Library is unique in the world. Nowhere else is there a collection of 500 testimonies from concentration camp survivors, recorded so soon after their terrible ordeal. Now, their stories from Ravensbrück will be made available in digital form, so that anyone can search the arch
https://www.staff.lu.se/article/important-testimonies-digitised - 2026-05-27
Tantalum spectra, emitted from a hollow cathode, have been recorded with a Fourier transform spectrometer in the region 2000–5000 Ů The observed hyperfine patterns of Ta II have been analyzed, yielding center-of-gravity wavelengths for 199 lines and hyperfine constants for 38 even and 97 odd levels of Ta II. Improved energy level values have been derived. The laboratory data have been used for a s
Bildandet av planeter äger rum i skivor av gas, stoft och is runt nybildade stjärnor. Den här processen är inte helt förstådd men det första steget tros vara växten från mikrometer-stora stoftkorn till mm-cm-stora småstenar genom sammanväxande kollisioner. Vid de här storlekarna studsar stenarna eller går sönder snarare än fastnar i varandra när de kolliderar så tillväxten avstannar. Dessutom kännPlanets form in protoplanetary discs of gas, dust and ice around newborn stars. In the Solar System, not only planets are found as a result from the time of planet formation, but also remnant planetesimals in the form of asteroids, Kuiper belt objects and comets. Recent observations, e.g. by the space mission Rosetta, have found that comets are porous objects barely able to hold themselves togethe
This thesis gives a thorough description of the icing mechanisms in gas turbines, the underlying physics of ice and ice types that can form in gas turbines. The primary intention of this thesis is to investigate the icing condition regions leading to ice formation in gas turbines. The icing problem in gas turbines is explained in detail in this thesis. The different ice types, icing mechanism
The dynamical stability of tightly packed exoplanetary systems remains poorly understood. While a sharp stability boundary exists for a two-planet system, numerical simulations of three-planet systems and higher show that they can experience instability on timescales up to billions of years. Moreover, an exponential trend between the planet orbital separation measured in units of Hill radii and th
We summarize the sensitivity achieved by the LIGO and Virgo gravitational wave detectors for compact binary coalescence (CBC) searches during LIGO's fifth science run and Virgo's first science run. We present noise spectral density curves for each of the four detectors that operated during these science runs which are representative of the typical performance achieved by the detectors for CBC sear
We report detections of weak emission lines in main sequence B starspectra observed at high spectral resolution and high signal-to-noiseratio. The emission lines originate from highly excited states ofsingle-ionized species. The mechanism for populating these excitedstates is currently under investigation and the results may have asignificant bearing upon our understanding of the outermost atmosph
ESA's Gaia mission will observe huge numbers of binaries with a largerange of periods. The present contribution presents results from somelarge-scale simulations, based on a simplified population synthesismodel Galaxy consisting mostly of binaries. The results are 'typical'solution-numbers and -types, for stellar samples at different distancesfrom the sun. As in previous studies, there are marked
P-mode oscillations in the Sun and stars are excited stochastically byReynolds stress and entropy fluctuations produced by convection in theirouter envelopes. The excitation rate of radial oscillations of starsnear the main sequence from K to F and a subgiant K IV star have beencalculated from numerical simulations of their surface convection zones.P-mode excitation increases with increasing effec
We present a calculation scheme with significant modifications and improvements for determining the ionization balance and the ion temperature evolution in an electron beam ion trap (EBIT). The scheme is applied to uranium and nitrogen ions using a specific set of EBIT operating parameters. The calculation results are compared to the experimental data. Rates for the individual atomic processes in
