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The spin effects in the hadronization process have been included for the first time in the PYTHIA 8 event generator. The spin effects are limited to the production of pseudo-scalar mesons and are obtained from the propagation of the quark polarization along the fragmentation chain according to the rules of the so-called 3P0 model. The interface between PYTHIA 8 and the package of the 3P0 model is
The first-order electroweak phase transition in the early universe could occur in multiple steps leading to specific multi-peaked signatures in the primordial gravitational wave (GW) spectrum. We argue that these signatures are generic phenomena in multi-scalar extensions of the Standard Model. In a simple example of such an extension, we have studied the emergence of reoccuring and nested vacuum
Perturbative QCD corrections to leptoproduction events can be introduced either in the form of matrix elements or of parton showers. Each of these approaches has its advantages and disadvantages, making a comparison of the two interesting. At present energies, both methods can be made to agree reasonably well with data, whereas differences appear at higher energies. The influence of these QCD effe
I will describe the current status of the PYTHIA7 project to completely rewrite the 'Lund family' of event generators in C++. The PYTHIA7 program is a general platform for implementing event generator models and is not limited to the standard Lund programs (PYTHIA, JETSET, ARIADNE,...). Also the future C++ version of the HERWIG program will be implemented in the PYTHIA7 framework. The underlying f
After months of relocations and renovation work, all the units involved have now come together in Geocentre II. As of 1 January 2026, the new Department of Earth and Environmental Sciences is in place, an occasion marked a few days ago with an internal housewarming gathering. An official inauguration will follow later this spring. Over the past few months, Geocentre II on Sölvegatan 12 in Lund has
https://www.mgeo.lu.se/internal/article/starting-point-new-department - 2026-05-27
How do I memorise the seen, what I am missing while I am looking at something?Although I am seeing, I miss what I am looking at. So every time I try to look at something again, it disappears every time my eye blinks. I only collected fragments during a day while walking around the whole city. The shops, parks, people and cars, so many of these I passed and nothing was left from my sight. I only re
In this review, we provide a short outlook of some of the current most popular pictures and promising approaches to non-perturbative physics and confinement in gauge theories. A qualitative and by no means exhaustive discussion presented here covers such key topics as the phases of QCD matter, the order parameters for confinement, the central vortex and monopole pictures of the QCD vacuum structur
A search for the K+ → π+X decay, where X is a long-lived feebly interacting particle, is performed through an interpretation of the K+ → π+νν¯ analysis of data collected in 2017 by the NA62 experiment at CERN. Two ranges of X masses, 0–110 MeV/c2 and 154–260 MeV/c2, and lifetimes above 100 ps are considered. The limits set on the branching ratio, BR(K+ → π+X), are competitive with previously repor
We propose a novel mechanism for the production of gravitational waves in the early Universe that originates from the relaxation processes induced by the QCD phase transition. While the energy density of the quark-gluon mean-field is monotonously decaying in real time, its pressure undergoes a series of violent oscillations at the characteristic QCD time scales that generate a primordial multi-pea
Several distinct color flow topologies are possible in multiparton configurations. A method is proposed to find the correct topology, based on a minimization of the total transverse momentum of produced particles. This method is studied for three-jet [Formula presented] and four-jet [Formula presented] events. It is shown how the basic picture is smeared, especially by parton-shower activity. The
All currently available QCD-inspired models/Monte Carlos for the event structure in high-p T physics are described. Included is information on hard interactions, initial and final state radiation, structure functions, beam jets and fragmentation. Results from a number of comparative Monte Carlo runs are presented, which help to illuminate how the physics content in Monte Carlos may be tested. Spec
In this talk we discuss a number of ChPT calculations relevant for lattice QCD. These include the finite volume corrections at two-loop order for masses and decay constants. The second part is about hadronic vacuum polarization where we present the two-loop ChPT estimate for the disconnected and strange quark contributions. We also present the finite volume corrections at two-loop order. The final
Charge balance functions reflect the evolution of charged pair correlations throughout the stagesof pair production, dynamical diffusion, and hadronization in heavy-ion collisions. Microscopic mod-eling of these correlations in the full collision volume shows that the balance functions are sensitiveto the diffusivity of light quarks when studied as functions of relative azimuthal angle. By restric
A new model of color reconnection in the Monte Carlo generator Herwig 7 is presented. It is based on the minimization of a boost-invariant distance of the parton system, where all partons have momentum as well as spacetime position assigned. We test the influence of both types of variables, namely the rapidity span and transverse distance, on the actual need to reconnect the system to better descr
It is shown that Technicolor model can be formulated having vector-like interaction of Techniquarks with the Standard Model bosons and Dirac mass term. Oblique corrections values for the case agree with experimental restrictions. The model Lagrangian is based on σ−model scheme introducing Techni-meson and Techni-baryon states. Neutral component of a "triplet" of heavy scalar Techni-baryons can be
We investigate how the uncertainties in σνN due the different QCD dynamic models would modify the neutrino absorption while they travel across the Earth. We compare the predictions of models based on the solution of the linear DGLAP equations at small-x and large-Q2 with those which impose the Froissart bound at large energies, taking into account the unitarity effects in the neutrino - nucleon cr
We present work going on calculating the kaon BK parameter in the 1/Nc expansion. The goal of this work is to analyze analytically in the presence of chiral corrections this phenomenologically very important parameter. We present the method used and preliminary results for the chiral limit value for which we get the invariant BKchi=0.29 +- 0.15. We also give some analytical indications of why the
These are the proceedings of the workshop on ``Effective Field Theories of QCD'' held at the Physikzentrum Bad Honnef of the Deutsche Physikalische Gesellschaft, Bad Honnef, Germany from November 26 to 30, 2001. The workshop concentrated on Chiral Perturbation Theory in its various settings, its relations with lattice QCD and dispersion theory and the use of effective field theories in systems wit
We investigate the implication of uncertainties in the unintegrated gluon distribution for the predictions for central exclusive production of scalars at hadron colliders. We use parameterizations of the k(perpendicular to)-unintegrated gluon density obtained from the Linked Dipole Chain model, applying different options for the treatment of non-leading terms. We find that the luminosity function
We show how to compute the two-loop sunset integrals at finite volume, for non-degenerate masses and non-zero momentum. We present results for all integrals that appear in the Chiral Perturbation Theory (chi PT) calculation of the pseudoscalar meson masses and decay constants at next-to-next-to-leading order, including the case of Partially Quenched chi PT. We also provide numerical implementation
