We discuss black hole thermodynamics in the manifestly duality invariant formalism of double field theory (DFT). We reformulate and prove the first law of black hole thermodynamics in DFT, using the covariant phase space approach. After splitting the full O(D, D) invariant DFT into a Kaluza-Klein-inspired form where only n coordinates are doubled, our results provide explicit duality invariant mass and entropy formulas. We illustrate how this works by discussing the black fundamental string solution and its T-duals.
To our best knowledge, the leading non-perturbative stringy interaction between an NS brane and a Dp brane remains unknown. We here present the non-perturbative stringy amplitudes for a system of an F-string and a Dp brane and a system of an NS 5 brane and a Dp brane for $0 \le p \le 6$. In either case, the F or NS5 and the Dp are placed parallel at a separation. We obtain the respective amplitudes, starting from the amplitude for a system of a D1 and a D3 for the former and that for a system of a D5 and a D3 system for the latter, based on the IIB S-duality and various T-dualities plus the co…
在弦论中，关于旋转等距的对偶变换将超对称背景与非超对称背景联系起来。我们发现，非局域世界片效应必须考虑，以恢复在弦水平的超对称性。基础的超共形代数保持不变，但在这种情况下，T-对偶将代数的局部实现与非局部实现联系起来。这是弦效应解决有效场论悖论的另一个例子。（对的里雅斯特S-对偶和镜像对称会议论文集的贡献;出现在Nucl Phys B Proc Suppl）
In this paper we discuss black hole solutions parametrized by their entropy $\mathcal{S}$ and temperature $\mathcal{T}$ in gravitational effective theories. We are especially interested in the analysis of the boundary regions in the $\mathcal{T}-\mathcal{S}$ diagram, i.e. large/small values of entropy and temperature, and their relation to Swampland constraints. To explore this correlation, we couple the gravitational theories to scalar fields and connect limits of thermodynamic quantities of black holes to scalar field excursions in the corresponding solutions. Whenever the scalar fields trav…
Stringy T-duality on the lattice and the twisted Villain model
Institute for Theoretical Physics and Astrophysics and Würzburg-Dresden Cluster of Excellence ctd.qmat, Julius-Maximilians-Universität Würzburg（维尔茨堡大学理论物理与天体物理研究所及维尔茨堡-德累斯顿卓越集群ctd.qmat）；Department of Quantitative Methods, CUNEF Universidad（CUNEF大学定量方法系）
We study string theory on $\mathbb{R}^d\times \mathbb{S}^1$. For applications to thermodynamics, the circumference of the $\mathbb{S}^1$ is the inverse temperature, $β$. We show that for $d=6$, the low energy effective field theory at the inverse Hagedorn temperature, $β=β_H$, has a one parameter family of normalizable spherically symmetric solutions that break the winding symmetry around the $\mathbb{S}^1$. The resulting backgrounds exhibit an enhanced symmetry, with the symmetry breaking pattern $SU(2)_L\times SU(2)_R\to SU(2)_{\rm diagonal}$. The effective field theory analysis of these bac…
Phase structures of 4D stringy charged black holes in canonical ensemble
在弦论中，研究了在任意介子耦合下，置于腔{ \it a la} York中的四维渐近平坦介子黑洞的热力学和相结构.我们在正则系综中考虑这些带电黑系统，其中腔壁温度和腔内电荷是固定的。我们发现，声子耦合起着关键的作用，在潜在的相结构。这些黑洞与高维膜系统通过对角（双）和/或直接降维的联系表明，前者的相结构可能穷尽后者的所有可能的相结构，后者在类似的条件下更难以研究。我们的研究还表明，一个对角（双）维减少保留了潜在的相结构，而直接降维有可能改变它。
We explore the stringy structure of 1/2-BPS bound states of NS fivebranes carrying momentum or fundamental string charge, in the decoupling limits leading to little string theory and to AdS3/CFT2 duality. We develop an exact worldsheet description of these states using null-gauged sigma models, and illustrate the construction by deriving the closed-form solution sourced by an elliptical NS5-F1 supertube. The Calabi-Yau/Landau-Ginsburg correspondence maps this geometrical worldsheet description to a non-compact LG model whose superpotential is determined by the fivebrane source configuration. S…
Dualities in D=5, N=2 Supergravity, Black Hole Entropy, and AdS Central Charges
从不同的角度讨论了D=5，N=2超引力场中一般黑洞与矢量多重态耦合的微观态计数问题。利用AdS_2的渐近对称代数中出现的中心荷计算了近极值情形的统计熵。此外，我们认为超引力理论享有的对偶不变性连接带电黑洞和磁荷黑弦。后者的近视界几何形状是AdS_3 x S^2，这使得可以用卡迪公式中的布朗-亨诺中心荷来微观计算它们的熵。在这两种方法中，我们发现统计熵和物理熵之间完全一致。
Geometric structures and dualities arise naturally in quantum field theories and string theory. In fact, these tools become very useful when studying strong coupling effects, where standard perturbative techniques can no longer be used. In this thesis we look at several conformal field theories in various dimensions. We first discuss the structure of the nilpotent networks stemming from T-brane deformations in 4D $\mathcal{N}=1$ theories and then go to the stringy origins of 6D superconformal field theories to realize deformations associated with T-branes in terms of simple combinatorial data.…
A general relativistic solution, composed of a Zel'dovich-Letelier interior made of radial strings matched through a spherical thin shell at radius $r_0$ to an exterior Schwarzschild solution with mass $m$, is presented. It is the Zel'dovich-Letelier-Schwarzschild star. When the radius $r_0$ of the star is shrunk to its gravitational radius $2m$, the solutions have interesting properties. There are solutions with $m=0$ and $r_0=0$ that obey $\frac{2m}{r_0}=1$. The solutions have a horizon, but are not black holes, they are quasiblack holes, though atypical. The proper mass $m_p$ of the interio…
We study thermodynamic geometry of certain black holes and black branes with and without generalized uncertainty principle or stringy $ α^{\prime} $-corrections to the entropy. From this perspective, we analyze Ruppenier geometry of Reissner-Nordström black holes and show that it is well defined and corresponds to a non-interacting statistical system. We investigate that the Weinhold geometry of dilatonic black holes is regular everywhere and that of large mass Reissner-Nordström black holes in the Poincaré patch of $ AdS_4 $ contains certain narrow range of thermodynamically unstable regions …
