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1. Refining the cutoff 3d gravity/$$ T\overline{T} $$ correspondence

   https://doi.org/10.1007/JHEP10(2022)094  

   Kraus, Per; Monten, Ruben; Roumpedakis, Konstantinos (October 2022, Journal of High Energy Physics)

   A bstract Pure gravity in AdS 3 is a theory of boundary excitations, most simply expressed as a constrained free scalar with an improved stress tensor that is needed to match the Brown-Henneaux central charge. Excising a finite part of AdS gives rise to a static gauge Nambu-Goto action for the boundary graviton. We show that this is the $$ T\overline{T} $$ T T ¯ deformation of the infinite volume theory, as the effect of the improvement term on the deformed action can be absorbed into a field redefinition. The classical gravitational stress tensor is reproduced order by order by the $$ T\overline{T} $$ T T ¯ trace equation. We calculate the finite volume energy spectrum in static gauge and find that the trace equation imposes sufficient constraints on the ordering ambiguities to guarantee agreement with the light-cone gauge prediction. The correlation functions, however, are not completely fixed by the trace equation. We show how both the gravitational action and the $$ T\overline{T} $$ T T ¯ deformation allow for finite improvement terms, and we match these to the undetermined total derivative terms in Zamolodchikov’s point splitting definition of the $$ T\overline{T} $$ T T ¯ operator. 

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2. Geometrizing $$ T\overline{T} $$

   https://doi.org/10.1007/JHEP03(2021)140  

   Caputa, Pawel; Datta, Shouvik; Jiang, Yunfeng; Kraus, Per (March 2021, Journal of High Energy Physics)

   null (Ed.)

   A bstract The $$ T\overline{T} $$ T T ¯ deformation can be formulated as a dynamical change of coordinates. We establish and generalize this relation to curved spaces by coupling the undeformed theory to 2d gravity. For curved space the dynamical change of coordinates is supplemented by a dynamical Weyl transformation. We also sharpen the holographic correspondence to cutoff AdS 3 in multiple ways. First, we show that the action of the annular region between the cutoff surface and the boundary of AdS 3 is given precisely by the $$ T\overline{T} $$ T T ¯ operator integrated over either the cutoff surface or the asymptotic boundary. Then we derive dynamical coordinate and Weyl transformations directly from the bulk. Finally, we reproduce the flow equation for the deformed stress tensor from the cutoff geometry. 

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3. Tensionless AdS3/CFT2 and single trace $$ T\overline{T} $$

   https://doi.org/10.1007/JHEP11(2024)145  

   Dei, Andrea; Knighton, Bob; Naderi, Kiarash; Sethi, Savdeep (November 2024, Journal of High Energy Physics)

   One of the few cases of AdS/CFT where both sides of the duality are under good control relates tensionlessk= 1 strings on AdS₃to a two-dimensional symmetric product CFT. Building on prior observations, we propose an exact duality between string theory on a spacetime which is not asymptotically AdS and a non-conformal field theory. The bulk theory is constructed as a marginal deformation of thek= 1 AdS₃string while the spacetime dual is a single trace$$ T\overline{T} $$ $T\overline{T}$-deformed symmetric orbifold theory. As evidence for the duality, we match the one-loop bulk and boundary torus partition functions. This correspondence provides a framework to both learn about quantum gravity beyond AdS and understand how to define physical observables in$$ T\overline{T} $$ $T\overline{T}$-deformed field theories. 

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4. S-duality in $$ T\overline{T} $$-deformed CFT

   https://doi.org/10.1007/JHEP05(2023)140  

   Benjamin, Nathan; Collier, Scott; Kruthoff, Jorrit; Verlinde, Herman; Zhang, Mengyang (May 2023, Journal of High Energy Physics)

   A bstract $$ T\overline{T} $$ T T ¯ deformed conformal field theories can be reformulated as worldsheet theories of non-critical strings. We use this correspondence to compute and study the $$ T\overline{T} $$ T T ¯ deformed partition sum of a symmetric product CFT. We find that it takes the form of a partition sum of a second quantized string theory with a worldsheet given by the product of the seed CFT and a gaussian sigma model with the two-torus as target space. We show that deformed symmetric product theory admits a natural UV completion that exhibits a strong weak coupling ℤ 2 duality that interchanges the momentum and winding numbers and maps the $$ T\overline{T} $$ T T ¯ -coupling λ to its inverse 1/ λ . The ℤ 2 duality is part of a full O(2, 2, ℤ)-duality group that includes a PSL(2, ℤ) acting on the complexified $$ T\overline{T} $$ T T ¯ coupling. The duality symmetry eliminates the appearance of complex energies at strong coupling for all seed CFTs with central charge c ≤ 6. 

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5. Malnutrition Disrupts T Cell Migration

   https://doi.org/10.4049/jimmunol.208.Supp.167.08  

   Dadzie, Kwesi A.; Foster, Takesha R; Mister, Abigail; Goulmamine, Syreen; Gibson, David; Adams, Olivia; Gubbels-Bupp, Melanie R (May 2022, The Journal of Immunology)

   Abstract Malnutrition is associated with reductions in the number and function of T lymphocytes. Previous studies in the lab suggest that malnutrition may also impart a “super-quiescent” phenotype to T cells, perhaps affecting the efficiency of their migration within and between lymph nodes. Thus, the purpose of this study is to evaluate the effect of malnutrition on T cell migration in vivo and to characterize malnutrition-induced changes in the expression of proteins known to be important for T cell migration. To determine if malnourishment alters T cell migration in vivo, we compared lymph node entry rates of adoptively-transferred malnourished and control T cells in malnourished and control recipients. In agreement with other studies, control CD4+ T cells were more efficient than control CD8+ T cells at entering the lymph nodes. Interestingly, regardless of recipient diet, malnourished CD4+ and CD8+ T cells entered the lymph nodes at equivalent rates, suggesting that malnourishment eliminates distinct lymph node entry efficiencies for CD8+ and CD4+ T cells. We also found important differences in the expression of key proteins involved in T cell migration between malnourished and control mice. Overall, we found that malnutrition disrupts T cell migration including the distinct migration efficiencies of CD4+ and CD8+ T cells. An improved understanding of T cell-intrinsic changes that occur during malnourishment should enhance our knowledge of CD4+ and CD8+ T cell migration and shed light on how organisms adapt to malnutrition. Supported by NSF-MRI [DBI- 1920116] NSF-RUI [IOS-1951881] 

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