University of Crete HEP Seminars
Weak Gravity Conjecture from Unitarity
| Speaker: | Yuta Hamada |
| Institution: | University of Crete |
| Time: | Thursday 13 September 2018, 14:15 |
| Venue: | 2nd floor seminar room |
| Abstract: | Weak Gravity Conjecture provides the lower bound on the Abelian gauge coupling in the theory of quantum gravity. In this talk, I will show that, under several assumptions, a class of weak gravity conjecture follows from the unitarity of the quantum field theory. |
Novel Results from The ALICE heavy-ion experiment at CERN
| Speaker: | Yiota Foka |
| Institution: | GSI and CERN |
| Time: | Tuesday 25 September 2018, 14:15 |
| Venue: | 2nd floor seminar room |
| Abstract: | Two-particle angular correlations were measured in pp collisions at p s = 7 TeV. The analysis was carried out for pions, kaons, protons, and lambdas, for all particle/anti-particle combinations in the pair. Data for mesons exhibit an expected peak dominated by effects associated with mini-jets and are well reproduced by general purpose Monte Carlo generators. However, for baryon - baryon and anti-baryon - anti-baryon pairs, where both particles have the same baryon number, a near-side anticorrelation structure is observed instead of a peak. This effect is interpreted in the context of baryon production mechanisms in the fragmentation process. It currently presents a challenge to Monte Carlo models and its origin remains an open question. |
SUSY Q and RG flows from spatially varying couplings
| Speaker: | Chris Rosen |
| Institution: | Imperial College London |
| Time: | Tuesday 6 November 2018, 14:15 |
| Venue: | 2nd floor seminar room |
| Abstract: | Many fundamental results on the behaviour of quantum field theories along a renormalisation group flow are established under the assumption of Poincare invariant deformations. Examples of which include celebrated monotonicity properties of various "a" and "c" functions, including those related to entanglement entropy. Comparatively little is known about the properties of renormalisation group flows driven by spatially dependent couplings for relevant operators. In this talk, I report on recent progress in addressing this deficiency. Towards this end, we construct (analytically and numerically) solutions to supergravity theories holographically dual to known superconformal field theories deformed by spatially varying mass terms for fermion and boson bilinears. The associated flows can exhibit novel features such as an "RG boomerang" which returns in the IR to the same UV fixed point up to a renormalisation of length scales. The flows preserve some supersymmetry, and can be embedded in eleven dimensional supergravity. Their "top-down" holographic pedigree further allows for a precise description of the flows in terms of their dual field theory's correlation functions, the correct computation of which involves a Legendre transform of the on-shell action as required by boundary supersymmetry. |
Leptogenesis via Neutrino Oscillation Magic
| Speaker: | Yuta Hamada |
| Institution: | University of Crete |
| Time: | Tuesday 13 November 2018, 14:15 |
| Venue: | 2nd floor seminar room |
| Abstract: | The possibility of generating the baryon asymmetry of the Universe via flavor oscillation in the early Universe is discussed. After the inflation, leptons are born in some states, travel in the medium, and are eventually projected onto flavor eigenstates due to the scattering via the Yukawa interactions. By using the Lagrangian of the Standard Model with the Majorana neutrino mass terms, llHH, we follow the time evolution of the density matrices of the leptons in this very first stage of the Universe and show that the CP violation in the flavor oscillation can explain the baryon asymmetry of the Universe. In the scenario where the reheating is caused by the decay of the inflaton into the Higgs bosons, the baryon asymmetry is generated by the CP phases in the Pontecorvo-Maki-Nakagawa-Sakata matrix and thus can be tested by the low energy neutrino experiments. |