Upcoming Seminars

Date/Place Nov. 20th (Tue.) 15:30-16:30 / H711
Name Tomonori Ugajin (OIST)
Title Modular Hamiltonians of excited states, OPE blocks and emergent bulk fields
Abstract We study the entanglement entropy and the modular Hamiltonian of slightly excited states reduced to a ball shaped region in generic conformal field theories. We set up a formal expansion in the one point functions of the state in which all orders are explicitly given in terms of integrals of multi-point functions along the vacuum modular flow, without a need for replica index analytic continuation. We show that the quadratic order contributions in this expansion can be calculated in a way expected from holography, namely via the bulk canonical energy for the entanglement entropy, and its variation for the modular Hamiltonian. The bulk fields contributing to the canonical energy are defined via the HKLL procedure. In terms of CFT variables, the contribution of each such bulk field to the modular Hamiltonian is given by the OPE block corresponding to the dual operator integrated along the vacuum modular flow. These results do not rely on assuming large N or other special properties of the CFT and therefore they are purely kinematic.


Date/Place Nov. 27th (Tue.) 15:30-16:30 / H711
Name Kazuya Yonekura (Kyushu University)
Title Black hole information and Reeh-Schlieder theorem
Abstract I will talk about implications of the Reeh-Schlieder theorem on the black hole information problem. In particular, I will argue that the Reeh-Schlieder theorem implies that “information” cannot be localized, and hence there is no well-defined concept of “information which is inside/outside event horizon”. Therefore, I claim that the black hole information problem is not well-formulated from the beginning.


Date/Place Dec. 3rd (Mon.) 16:30-17:30 / H711
Name Valentin Tenorth (Max Planck Heidelberg)
Title Extended Dark Matter EFT
Abstract The search for Dark Matter is one of the main tasks of modern particle physics, which is performed in "mono-X" searches at the LHC, indirect and direct detection experiments. I present a new framework in the language of effective field theory (EFT) to describe DM-SM interactions and combine experimental limits from nuclear energies at Direct Detection experiments to the TeV-scale at the LHC.To improve the high energy-validity of conventional DM EFTs a dynamical (pseudo-) scalar is added serving as mediator to the dark sector, represented by a fermion (or scalar), where richer new-physics sectors can be consistently included via higher-dimensional operators. The model is formulated in a gauge-invariant way and allows to confront classical Dark Matter observables with measurements of the Higgs sector.Interestingly the leading effects originate at dimension-five, allowing to capture them with a rather small set of parameters.Constraints on the parameter space arising from collider mono-X searches, the relic abundance, indirect and direct detection experiments are presented.The "model-independent" approach allows to apply the results to different UV-complete models such as 2HDM+a, extended fermion sectors, the NMSSM and composite mediators.In a (shorter) second part I discuss an approach to the SM flavor hierarchies and DM from the EW scale with a minimal new field content. Both the flavon and a pseudoscalar mediator to the Dark Sector arise from a combination of two flavor-charged Higgs Doublets. This leads to a predictive model with an interesting and rich phenomenology, which can be tested in different experiments in the near future.


Date/Place Dec. 4th (Tue.) 15:30-16:30 / H711
Name Cen Zhang (IHEP, Beijing)
Title Positivity bounds on vector boson scattering
Abstract Weak vector boson scattering (VBS) process is a sensitive probe of new physics effects in the electroweak symmetry breaking. Currently, experimental results at the LHC are interpreted in the effective field theory (EFT) approach, where possible deviations from the Standard Model in the quartic-gauge-boson couplings are described by 18 dimension-8 operators. By assuming that a UV completion exists, we derive a new set of theoretical constraints on the coefficients of these EFT operators, i.e. certain linear combinations of coefficients must be positive. These constraints imply that the current EFT approach to VBS has a large redundancy: only ∼3% of the full parameter space may correspond to a real UV completion. By excluding the unphysical region of the EFT parameter space, these constraints provide guidance for future VBS studies and measurements at the LHC.


Past Seminars