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New stable particles with fairly low masses could exist if the coupling to the Standard Model is weak, and with suitable parameters they might be possible to produce at the LHC. Here we study a selection of models with the new particles being charged under a new gauge group, either U(1) or SU(N). In the Abelian case there will be radiation of gammavs, which decay back into the SM. In the non-Abeli
This talk is about the hadronic light-by-light contribution to the muon anomalous magnetic moment, mainly our old work but including some newer results as well. It concentrates on the model calculations. Most attention is paid to pseudo-scalar exchange and the pion loop contribution. Scalar, a1-exchange and other contributions are shortly discussed as well. For the π0-exchange a possible large can
The recent experimental measurement of the muon g−2 at Fermilab National Laboratory, at a 4.2σ tension with the Standard Model prediction, highlights the need for further improvements on the theoretical uncertainties associated to the hadronic sector. In the framework of the operator product expansion in the presence of a background feld, the short-distance behaviour of the hadronic light-by-light
I present higher loop order results for several calculations in Chiral perturbation Theory. 1) Two-loop results at finite volume for hadronic vacuum polarization. 2) A three-loop calculation of the pion mass and decay constant in two-flavour ChPT. For the pion mass all needed auxiliary parameters can be determined from lattice calculations of ππ-scattering. 3) Chiral corrections to neutron-anti-ne
Heavy long-lived quarks, i.e. charm and bottom, are frequently studied both as tests of QCD and as probes for other physics aspects within and beyond the standard model. The long lifetime implies that charm and bottom hadrons are formed and observed. This hadronization process cannot be studied in isolation, but depends on the production environment. Within the framework of the string model, a maj
We review the factorization theorem for the production of a heavy color-neutral final state with a transverse momentum much smaller than its invariant mass in the framework of soft collinear effective field theory (SCET). This phase space region is plagued by large logarithms of widely separated scales, including large logarithms of rapidity ratios, that need to be resummed for sensible results. I
In this thesis a chirally symmetric technicolor model is investigated as an extension to the Standard Model. The extension is based on low-energy QCD, with a linear sigma model used to induce the additional degrees of freedom corresponding to the lightest particles of the new techni-sector. The main goal is to incorporate the Standard Model Higgs into the new model, as to explain its vacuum expect
This thesis considers the low-energy effective field theory of a new technicolor extension. The extension preserves the Standard Model Higgs boson and introduces a chirally symmetric technifermion sector, in the framework of the gauged linear sigma model. In the nearly conformal limit, the considered extension leads to a common origin of the Higgs- and Technisigma vacuum expectation values, relate
High energy particle collisions involve complex physics, beyond analytical control. Instead, Monte Carlo event generators like Pythia have been used to simulate particle collisions since decades. A study of the production of heavy quarks (namely, charm and bottom) is presented for two different scenarios: lepton (e+e−) and hadron (pp) collisions. Electron- positron collisions at the Z0 resonance a
A third workshop on small-x physics, within the Small-x Collaboration, was held in Hamburg in May 2004 with the aim of overviewing recent theoretical progress in this area and summarizing the experimental status.
We present a flexible and efficient program package written in C++, PROFASI, for simulating protein folding and aggregation. The systems are modeled using an all-atom description of the protein chains with only torsional degrees of freedom, and implicit water. The program package has a modular structure that makes the interaction potential easy to modify. The currently implemented potential is abl
We compute the energy levels of an SU(2) Yang-Mills field in perturbation theory to order g2, for a box of finite size and symmetric twist m=(1, 1, 1). A cubic-invariant spectrum results, with almost degenerate E++ and T2 ++ levels. Various suggestions for further MC measurements are made.
This thesis investigates the use of artificial neural networks for classifying Raman spectra of partially degraded cellulose samples by fungal species. A multilayer perceptron configuration of 4 hidden layers and 128 hidden nodes was able to classify a set of 60 samples with an overall prediction accuracy of 0.55. Results show that data resolution is an important factor when optimizing classifier
