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Seminare im Jahr 2018

Seminare in früheren Jahren

Dozent/Speaker: Prof. Dr. Michal Praszalowicz (Jagiellonian University, Krakow)
Termin/Date: Fr. 27.04.2018, 16:15 - 17:45
Ort/Location: NB 6/173
Übersicht/Abstract: Recent measurements of the total pp cross-section and the so called rho parameter by the TOTEM Collaboration at the LHC cannot be reconciled with the parametrizations of the forward scattering amplitude that does not include a C-parity odd contribution, so called odderon. We shall¬† review the S matrix approach to the low momentum transfer processes introducing the concepts of Regge trajectories, Pomeron and odderon. QCD interpretation of the Pomeron and the odderon will be discussed. Finally we shall present recent analysis of the TOTEM data that seem to indicate the evidence for the odderon.
Will be announced soon
Dozent/Speaker: Prof. Dr. A.L. Kataev (INR RAS, Moscow)
Termin/Date: Do. 26.04.2018, 16:15 - 17:45
Ort/Location: NB 6/173
Übersicht/Abstract: Scheme and gauge (in)dependence of the ¬†generalized Crewther relation between e^+e^- - annihilation Adler function and polarised Bjorken sum rule in perturbative QCD and the $\]beta$-function factorization property
On a possibility of baryonic exotica
Dozent/Speaker: Prof. Dr. Michal Praszalowicz (Jagiellonian University, Krakow)
Termin/Date: Do. 19.04.2018, 16:15 - 17:45
Ort/Location: NB 6/173
Übersicht/Abstract: Models based on chiral symmetry predict the baryonic states with exotic quantum numbers (pentaquarks) that have relatively low masses and small widths. We shall briefly review both theoretical and experimental status of a possibility of exotica in the light sector. Next we shall show how to extend chiral models to baryons with one heavy quark and show that one may expect exotic states also in this case. Finally we shall try to interpret recently discovered by the LHCb collaboration five Omega^*_c resonances in terms of regular and exotic excitations of the ground state Omega_c.
Neutrinoless double beta decay in effective field theory
Dozent/Speaker: Dr. Jordy de Vries (NIKHEF, Amsterdam)
Termin/Date: Di. 13.02.2018, 16:15 - 17:45
Ort/Location: NB 6/173
Übersicht/Abstract: Next-generation neutrinoless double-beta decay experiments aim to discover lepton-number violation in order to shed light on the nature of neutrino masses. A non-zero signal would have profound implications by demonstrating the existence of elementary Majorana particles and possibly pointing towards a solution of matter-antimatter asymmetry in the universe. However, the interpretation of the experimental signal (or lack thereof) requires care. First of all, a single nonzero measurement would indicate lepton-number violation but will not identify the underlying source. Second, complicated hadronic and nuclear input is required to connect the experimental data to a fundamental description of lepton-number violation. In this talk, I will use effective field theories to describe neutrinoless double-beta decay processes. In particular, I will apply the Standard Model effective field theory and chiral effective field theory to bridge the gap between high-energy models of lepton-number violation to neutrinoless double-beta decay experiments.
Few-neutron resonance study using transition operators
Dozent/Speaker: Dr. Arnoldas Deltuva (Vilnius University)
Termin/Date: Do. 01.02.2018, 16:15 - 17:45
Ort/Location: NB 6/173
Übersicht/Abstract: Existing bound-state type calculations of few-neutron resonances yield contradicting results. A direct study of the three- and four-neutron continuum using rigorous scattering equations with realistic potentials and search for possible resonances is aimed. Faddeev-type integral equations for transition operators are solved in the momentum-space partial-wave framework. The evolution of resonances is studied by enhancing the strength of the two-neutron interaction in partial waves with nonzero orbital momentum. Calculated few-neutron transition operators exhibit resonant behavior for sufficiently large enhancement factors; pole trajectories in the complex-energy energy plane are extracted from their energy dependence. However, the resonant behavior completely disappears for the physical interaction strength.
Production of tensor glueball in reaction $\gamma\gamma\rightarrow G_2\pi^0$
Dozent/Speaker: Dr. N. Kivel (Universität Mainz)
Termin/Date: Do. 11.01.2018, 16:15 - 17:45
Ort/Location: NB 6/173
Übersicht/Abstract: We studied production of tensor glueball in the reaction $\gamma\gamma\rightarrow G_2\pi^0$ at large energy and large scattering angles.
The scattering amplitude is computed within the collinear factorisation framework that allows us to estimate the cross section. We obtained that if the value of the tensor gluon coupling is not too small $f^T_g\sim 100$~MeV then the cross section can be measured in the future BELLE-II experiment.