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DTSTART;TZID=America/New_York:20220511T103000
DTEND;TZID=America/New_York:20220511T120000
DTSTAMP:20260618T153005
CREATED:20240214T100851Z
LAST-MODIFIED:20240813T163022Z
UID:10002659-1652265000-1652270400@cmsa.fas.harvard.edu
SUMMARY:Cosmology from the vacuum
DESCRIPTION:Abstract: We are familiar with the idea that quantum gravity in AdS can holographically emerge from complex patterns of entanglement\, but can the physics of big bang cosmology emerge from a quantum many-body system? In this talk I will argue that standard tools of holography can be used to describe fully non-perturbative microscopic models of cosmology in which a period of accelerated expansion may result from the positive potential energy of time-dependent scalar fields evolving towards a region with negative potential. In these models\, the fundamental cosmological constant is negative\, and the universe eventually recollapses in a time-reversal symmetric way. The microscopic description naturally selects a special state for the cosmology. In this framework\, physics in the cosmological spacetime is dual to the vacuum physics in a static planar asymptotically AdS Lorentzian wormhole spacetime\, in the sense that the background spacetimes and observables are related by analytic continuation. The dual spacetime is weakly curved everywhere\, so any cosmological observables can be computed in the dual picture via effective field theory without detailed knowledge of the UV completion or the physics near the big bang. Based on 2203.11220 with S. Antonini\, P. Simidzija\, and M. Van Raamsdonk.
URL:https://cmsa.fas.harvard.edu/event/5-11-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:MA
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-05.11.22-1583x2048-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220512T103000
DTEND;TZID=America/New_York:20220512T120000
DTSTAMP:20260618T153005
CREATED:20240214T100601Z
LAST-MODIFIED:20240813T163153Z
UID:10002656-1652351400-1652356800@cmsa.fas.harvard.edu
SUMMARY:Oblique Lessons from the W Mass Measurement at CDF II
DESCRIPTION:Abstract: The CDF collaboration recently reported a new precise measurement of the W boson mass MW with a central value significantly larger than the SM prediction. We explore the effects of including this new measurement on a fit of the Standard Model (SM) to electroweak precision data. We characterize the tension of this new measurement with the SM and explore potential beyond the SM phenomena within the electroweak sector in terms of the oblique parameters S\, T and U. We show that the large MW value can be accommodated in the fit by a large\, nonzero value of U\, which is difficult to construct in explicit models. Assuming U = 0\, the electroweak fit strongly prefers large\, positive values of T. Finally\, we study how the preferred values of the oblique parameters may be generated in the context of models affecting the electroweak sector at tree- and loop-level. In particular\, we demonstrate that the preferred values of T and S can be generated with a real SU(2)L triplet scalar\, the humble swino\, which can be heavy enough to evade current collider constraints\, or by (multiple) species of a singlet-doublet fermion pair. We highlight challenges in constructing other simple models\, such as a dark photon\, for explaining a large MW value\, and several directions for further study.
URL:https://cmsa.fas.harvard.edu/event/5-12-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:MA
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-05.12.22-1583x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220518T160000
DTEND;TZID=America/New_York:20220518T173000
DTSTAMP:20260618T153005
CREATED:20240214T095418Z
LAST-MODIFIED:20240813T163304Z
UID:10002651-1652889600-1652895000@cmsa.fas.harvard.edu
SUMMARY:The Generalized Landau Paradigm (a review of generalized symmetries in condensed matter)
DESCRIPTION:Abstract: Recent advances in our understanding of symmetry in quantum many-body systems offer the possibility of a generalized Landau paradigm that encompasses all equilibrium phases of matter. This talk will be an elementary review of some of these developments\, based on: https://arxiv.org/abs/2204.03045
URL:https://cmsa.fas.harvard.edu/event/5-18-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-05.18.22-1583x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220518T160000
DTEND;TZID=America/New_York:20220518T173000
DTSTAMP:20260618T153005
CREATED:20240215T101105Z
LAST-MODIFIED:20240813T162341Z
UID:10002739-1652889600-1652895000@cmsa.fas.harvard.edu
SUMMARY:Boundary conditions and LSM anomalies of conformal field theories in 1+1 dimensions
DESCRIPTION:Speaker: Linhao Li (ISSP\, U Tokyo) \nTitle: Boundary conditions and LSM anomalies of conformal field theories in 1+1 dimensions \nAbstract: In this talk\, we will study a relationship between conformally invariant boundary conditions and anomalies of conformal field theories (CFTs) in 1+1 dimensions. For a given CFT with a global symmetry\, we consider symmetric gapping potentials which are relevant perturbations to the CFT. If a gapping potential is introduced only in a subregion of the system\, it provides a certain boundary condition to the CFT. From this equivalence\, if there exists a Cardy boundary state which is invariant under a symmetry\, then the CFT can be gapped with a unique ground state by adding the corresponding gapping potential. This means that the symmetry of the CFT is anomaly free. Using this approach\, we will systematically deduce the anomaly-free conditions for various types of CFTs with several different symmetries. When the symmetry of the CFT is anomalous\, it implies a Lieb-Schultz-Mattis type ingappability of the system. Our results are consistent with\, where available\, known results in the literature. Moreover\, we extend the discussion to other symmetries including spin groups and generalized time-reversal symmetries. As an application\, we propose 1d LSM theorem involving magnetic space group symmetries on the lattice. The extended LSM theorems apply to systems with a broader class of spin interactions\, such as Dzyaloshinskii-Moriya interactions and chiral three-spin interactions.
URL:https://cmsa.fas.harvard.edu/event/5-18-2022-quantum-matter-in-mathematics-and-physics-2/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-05.18.22-1583x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220525T103000
DTEND;TZID=America/New_York:20220525T120000
DTSTAMP:20260618T153005
CREATED:20240215T101805Z
LAST-MODIFIED:20240215T102153Z
UID:10002740-1653474600-1653480000@cmsa.fas.harvard.edu
SUMMARY:Oblique Lessons from the W Mass Measurement at CDF II
DESCRIPTION:Speaker: Seth Koren (University of Chicago) \nTitle: Baryon Minus Lepton Number BF Theory for the Cosmological Lithium Problem \nAbstract: The cosmological lithium problem—that the observed primordial abundance is lower than theoretical expectations by order one—is perhaps the most statistically significant anomaly of SM+ ΛCDM\, and has resisted decades of attempts by cosmologists\, nuclear physicists\, and astronomers alike to root out systematics. We upgrade a discrete subgroup of the anomaly-free global symmetry of the SM to an infrared gauge symmetry\, and UV complete this at a scale Λ as the familiar U(1)_{B-N_cL} Abelian Higgs theory. The early universe phase transition forms cosmic strings which are charged under the emergent higher-form symmetry of the baryon minus lepton BF theory. These topological defects catalyze interactions which turn N_g baryons into N_g leptons at strong scale rates in an analogue of the Callan-Rubakov effect\, where N_g=3 is the number of SM generations. We write down a model in which baryon minus lepton strings superconduct bosonic global baryon plus lepton number currents and catalyze solely 3p^+ → 3e^+. We suggest that such cosmic strings have disintegrated O(1) of the lithium nuclei formed during Big Bang Nucleosynthesis and estimate the rate\, with our benchmark model finding Λ ~ 10^8 GeV gives the right number density of strings.
URL:https://cmsa.fas.harvard.edu/event/qm_51222/
LOCATION:Hybrid
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-Seminar-05.25.22.png
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