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DTSTART;TZID=Europe/Ljubljana:20240912T140000
DTEND;TZID=Europe/Ljubljana:20240912T150000
DTSTAMP:20260423T184234
CREATED:20240827T122432Z
LAST-MODIFIED:20240912T130001Z
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SUMMARY:Pietro Baratella: Journal Club on WZW terms without anomalies: generalised symmetries in chiral Lagrangians
DESCRIPTION:Journal Club on WZW terms without anomalies: generalised symmetries in chiral Lagrangians (arXiv:2407.20340)Abstract:We consider a 4d non-linear sigma model on the coset $(text{SU}(N)_L times text{SU}(N)_R times text{SU}(2))/(text{SU}(N)_{L+R}times text{U})cong text{SU}(N) times S^2$\, that features a topological Wess–Zumino–Witten (WZW) term whose curvature is $frac{n}{24pi^2}text{Tr}(g^{-1}dg)^3 wedge mathrm{Vol}_{S^2}$ where $g$ is the $text{SU}(N)$ pion field. This WZW term\, unlike its familiar cousin in QCD\, does not match any chiral anomaly\,so its microscopic origin is not obviously QCD-like. We find that generalised symmetries provide a key to unlocking a UV completion.The $S^2$ winding number bestows the theory with a 1-form symmetry\, and the WZW term intertwines this with the $text{SU}(N)^2$ flavour symmetry into a 2-group global symmetry. Like a ‘t Hooft anomaly\, the 2-group symmetry should match between UV and IR\, precluding QCD-like completions that otherwise give the right pion manifold. We instead construct a weakly-coupled UV completion that matches the 2-group symmetry\, in which an abelian gauge field connects the QCD baryon number current to the winding number current of a $mathbb{C}P^1$ model\, and explicitly show how the mixed WZW term arises upon flowing to the IR. The coefficient is fixed to be the number of QCD colours and\, strikingly\, this matching must be `tree-level exact’ to satisfy a quantization condition.We discuss generalisations\, and elucidate the more intricate generalised symmetry structure that arises upon gauging an anomaly-free subgroup of $text{SU}(N)_{L+R}$. This WZW term may even play a phenomenological role as a portal to a dark sector\, that determines the relic abundance of dark matter.\nhttps://indico.ijs.si/event/2259/
URL:https://web-f1.ijs.si/event/pietro-baratella-journal-club-on-wzw-terms-without-anomalies-generalised-symmetries-in-chiral-lagrangians/
LOCATION:https://zoom.us/j/3601731049?pwd=bVNQRjUxU2ExZ0cveWcxYXNUUGdjZz09 (F1 tea room)
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DTSTART;TZID=Europe/Ljubljana:20240912T141500
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SUMMARY:Nataša Adžić\, "The role of effective interactions in predicting the exotic states of soft matter"
DESCRIPTION:Speakers: Nataša Adžič (Institute of Physics\, Belgrade)\n Studying static properties of colloidal suspensions is often a computationally expensive task due to their complex composition and interactions that appear at various length scales. Large macromolecules are surrounded by small solute particles and typically some other small components such as salt ions. One of the useful coarse-graining tools for studying self-organisation of macromolecules in solutions is the method of effective interactions. It is based on calculation of the effective Hamiltonian as a canonical trace over small degrees of freedom for the given fixed configuration of large ones . The calculated effective interaction can be further employed in Monte Carlo simulations between effective point particles that mimic behaviour of large macromolecules. In that way a fast scan of their phase organisation can be obtained. In this talk we will see how this method applies to self-organisation of various all-DNA dendrimers\, macromolecules composed solely of short segments of DNA chains .     R. Blaak\, B. Capone\, C. N. Likos\, and L. Rovigatti\, Accurate Coarse-Grained Potentials for Soft Matter Systems\, in Computational Trends in Solvation and Transport in Liquids – Lecture Notes\, IAS Series\, Vol. 28\, 2015. N. Adzic\, C. Jochum\, C. N. Likos\, and E. Stiakakis\, “Engineering Ultrasoft Interactions in Stiff All-DNA Dendrimers by Site-Specific Control of Scaffold Flexibility”\, Small 2023\, 2308763 (2024). E. Stiakakis\, N. Jung\, N. Adzic\, T. Balandin\, E. Kentzinger\, U. Rucker\, R. Biehl\, J. Dhont\, U. Jonas\, and C. N. Likos\, “Self Assembling Cluster Crystals from DNA Based Dendritic Nanostructres”\, Nat. Commun. 12\, 7167 (2021). N. Adzic\, C. Jochum\, E. Stiakakis\, G. Kahl\, C.N. Likos\, “Self-organisation of planar and tripod-shaped DNA stars confined to the water-air interface”\, in preparation for submission\nhttps://indico.ijs.si/event/2262/
URL:https://web-f1.ijs.si/event/natasa-adzic-the-role-of-effective-interactions-in-predicting-the-exotic-states-of-soft-matter/
LOCATION:Seminar room of physics (106) (IJS)
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