517 research outputs found
Quantum Gravity and Predictions for our Universe
No full textIn this talk I provide an executive summary of some of the recent progress that has been made in understanding some key features of quantum gravitational theories. This is rooted in lessons learned from the landscape of consistent solutions to string theory and captured by the principles of the Swampland program. A key feature of this is the lack of decoupling between short and long distance descriptions of the theory leading to a radical revision of the notion of consistency of effective field theories. This opens up a new window into unresolved fine tuning problems for particle physics and cosmology. I will further explain how these ideas lead to concrete experimentally verifiable predictions for our universe.
Cumrun Vafa Cumrun Vafa is the Hollis Professor of Mathematicks and Natural Philosophy in the Physics Department at Harvard University, where he does research and teaches theoretical physics since 1985. Born in Iran in 1960, he moved to the US for higher education where he received his B.S. in math and physics from MIT before moving to Princeton University, where he received his Ph.D. in theoretical physics.
Coffee and tea served at 16:00pm</p
G(2) holonomy, Taubes' construction of Seiberg-Witten invariants and superconducting vortices
No full textUsing a reformulation of topological N = 2 QFT’s in M-theory setup, where QFT is realized via M5 branes wrapping co-associative cycles in a G2 manifold constructed from the space of self-dual 2-forms over a four-fold X, we show that superconducting vortices are mapped to M2 branes stretched between M5 branes. This setup provides a physical explanation of Taubes’ construction of the Seiberg-Witten invariants when X is symplectic and the superconducting vortices are realized as pseudo-holomorphic curves. This setup is general enough to realize topological QFT’s arising from N = 2 QFT’s from all Gaiotto theories on arbitrary 4-manifolds. © 2020, The Author(s)
Interplay between String Theory, Particle Physics and Cosmology
No full textAs part of the event: "The case of the (still) mysterious Universe", presentation of Irene Valenzula and Cumrun Vafa about Interplay between String Theory, Particle Physics and Cosmolog
Exact results for supersymmetric sigma models
No full textWe show that the metric and Berry's curvature for the ground states of N = 2 supersymmetric sigma-models can be computed exactly as one varies the Kahler structure. For the case of CP(n) these are related to special solutions of affine Toda equations. This allows us to extract exact results. We find that the ground-state metric is nonsingular as the size of the manifold shrinks to zero, suggesting that 2D quantum field theory makes sense even beyond zero radius. Thus it seems that manifolds with zero size are nonsingular as target spaces for string theory (even when they are not conformal)
İsmail Bey Gutgaşınlı, the one of the Azerbaijan Educators and his first story under the effect of Europe: Reşit Bey and Saadet Hanim
No full textl9th century was period during which mutual relations among cultures and literatures became strong and accelerated, and was session that Azerbaijani literature broke the patterns of regionalism, adapted to world literature in some degree. In the first quarter of l9th century, new generation of intellectuals grew, progress and development occurred in all areas of Cultural life in Azerbaijan. Changing people due to modernized life, forced literature to get new shape and new styles, thus new way opened in prose genre of Azerbaijani literature. İsmail Bey Gutgaşınlı was one of the first ambassadors of this newness. Author attach importance to show mental anguishes, feelings and thoughts about problems in social life of characters in his literary work "Reşit Bey ve Saadet Hanım" that author wrote in Warsaw during his military service. Author used commitment to soil and nature as motif. The author who has grasp of both eastern and western culture, made effort to synthesize the positive sides of this two dili'erent cultural systems in the personality of his characters. The work is important, For it played the first role in the rise of consciousness bound to realism in Azerbaijani literature.Kültürler ve edebiyatlar arası karşılıklı ilişkilerin güçlendiği ve hızlandığı bir dönem olan XIX. yüzyıl, Azerbaycan edebiyatının da mahalliliğin kalıplarını kırdığı, bir ölçüde de olsa dünya edebiyatına uyum sağlama sürecine girdiği bir devre olmuştur. XIX. yüzyılın ilk çeyreğinde Azerbaycan'da daha yeni bir aydın nesil yetişmiş, kültür hayatının bütün alanlarında bir ilerleme ve gelişme yaşanmıştır. Yenileşen hayatla birlikte belli bir değişime uğrayan insanlar, edebiyatı da yeni şekil ve yeni tarzlara zorlamış, böylece Azerbaycan edebiyatında nesir türünde yeni bir çığır açılmıştır. İsmail Bey Gutgaşınlı, bu yeniliğin ilk temsilcilerinden olmuştur. Yazarın Varşova'da askeri hizmetteyken kaleme aldığı "Reşit Bey ve Saadet Hanım" isimli eseri kahramanlarının ruhsal ıstıraplarının yanı sıra onların sosyal hayatla, yaşanılan zamanla, toplum içerisinde karşılaştıkları problemlerle ilgili duygu ve düşüncelerini yansıtmaya önem vermiştir. Yazar, eserde toprağa ve tabiata bağlılığı motif olarak kullanmıştır. Hem Doğu hem de Batı kültürüne vâkıf olan yazar, kendi kahramanlarının şahsında bu iki Farklı kültür sisteminin olumlu yönlerinin sentezine çaba göstermiştir. Eser, Azerbaycan edebiyatında realizme bağlı bir şuurun uyanmasında ilk rolü oynadığından önem taşımaktadır
tt * geometry in 3 and 4 dimensions
No full textWe consider the vacuum geometry of supersymmetric theories with 4 supercharges, on a flat toroidal geometry. The 2 dimensional vacuum geometry is known to be captured by the tt* geometry. In the case of 3 dimensions, the parameter space is (T2 x R)N and the vacuum geometry turns out to be a solution to a generalization of monopole equations in 3N dimensions where the relevant topological ring is that of line operators. We compute the generalization of the 2d cigar amplitudes, which lead to S2 x S1 or S3 partition functions which are distinct from the supersymmetric partition functions on these spaces, but reduce to them in a certain limit. We show the sense in which these amplitudes generalize the structure of 3d Chern-Simons theories and 2d RCFT's. In the case of 4 dimensions the parameter space is of the form XM,N = (T3 * R) M * T3N, and the vacuum geometry is a solution to a mixture of generalized monopole equations and generalized instanton equations (known as hyper-holomorphic connections). In this case the topological rings are associated to surface operators. We discuss the physical meaning of the generalized Nahm transforms which act on all of these geometries. © The Authors
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A stringy test of the fate of the conifold
No full textBy studying string loop corrections to the superpotential of Type LI strings compactified on Calabi-Yau threefolds we find a quantum stringy test and a confirmation of a recent proposal of Strominger on the fate of the conifold singularity, We also propose a connection between the spectrum of Bogomolnyi saturated solitons and the one-loop string partition function of N = 2 topological strings.Accepted Manuscrip
Ray-Singer Torsion, Topological Strings and Black Holes
No full textGenus one amplitude for topological strings on Calabi-Yau 3-folds can be
computed using mirror symmetry: The partition function at genus one gets mapped
to a holomorphic version of Ray-Singer torsion on the mirror Calabi-Yau. On the
other hand it can be shown by a physical argument that this gives a curvature
squared correction term to the gravitational action. This in paticular leads to
an effective quantum gravity cutoff known as the species scale, which varies
over moduli space of Calabi-Yau manifolds. This resolves some of the puzzles
associated to the entropy of small black holes when there are a large number of
light species of particles. Thus Ray-Singer torsion, via its connection to
topological strings at genus one, provides a measure of light degrees of
freedom of four dimensional N=2 supergravity theories. Based on a talk given on
May 12th, 2023 at the Singer Memorial Conference, MIT.Comment: 11 page
Twisted sheaves and SU(r)/Z_r Vafa-Witten theory
No full textThe SU (r) Vafa–Witten partition function, which virtually counts Higgs pairs on a projective surface S, was mathematically defined by Tanaka–Thomas. On the Langlands dual side, the first-named author recently introduced virtual counts of Higgs pairs on μ r-gerbes. In this paper, we instead use Yoshioka’s moduli spaces of twisted sheaves. Using Chern character twisted by rational B-field, we give a new mathematical definition of the SU (r) / Z r Vafa-Witten partition function when r is prime. Our definition uses the period-index theorem of de Jong. S-duality, a concept from physics, predicts that the SU (r) and SU (r) / Z r partition functions are related by a modular transformation. We turn this into a mathematical conjecture, which we prove for all K3 surfaces and prime numbers r
Twisted sheaves and SU(r)/Z_r Vafa-Witten theory
No full textThe SU (r) Vafa–Witten partition function, which virtually counts Higgs pairs on a projective surface S, was mathematically defined by Tanaka–Thomas. On the Langlands dual side, the first-named author recently introduced virtual counts of Higgs pairs on μ r-gerbes. In this paper, we instead use Yoshioka’s moduli spaces of twisted sheaves. Using Chern character twisted by rational B-field, we give a new mathematical definition of the SU (r) / Z r Vafa-Witten partition function when r is prime. Our definition uses the period-index theorem of de Jong. S-duality, a concept from physics, predicts that the SU (r) and SU (r) / Z r partition functions are related by a modular transformation. We turn this into a mathematical conjecture, which we prove for all K3 surfaces and prime numbers r
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