Fri - 07/26/24

There is no new related paper today

There is no new related paper today

  1. [] - Title: Monte Carlo studies of quantum cosmology by the generalized Lefschetz thimble method - Chien-Yu Chou, Jun Nishimura

Thu - 07/25/24

**Title:

      A better space of generalized connections**  - **Authors:** Juan Orendain, Jose A. Zapata  - **Subjects:** Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Lattice (hep-lat)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  Given a base manifold $M$ and a Lie group $G$, we define $\widetilde{\cal A}_M$ a space of generalized $G$-connections on $M$ with the following properties: - The space of smooth connections ${\cal A}^\infty_M = \sqcup_\pi {\cal A}^\infty_\pi$ is densely embedded in $\widetilde{\cal A}_M = \sqcup_\pi \widetilde{\cal A}^\infty_\pi$; moreover, in contrast with the usual space of generalized connections, the embedding preserves topological sectors. - It is a homogeneous covering space for the standard space of generalized connections of loop quantization $\bar{\cal A}_M$. - It is a measurable space constructed as an inverse limit of of spaces of connections with a cutoff, much like $\bar{\cal A}_M$. At each level of the cutoff, a Haar measure, a BF measure and heat kernel measures can be defined. - The topological charge of generalized connections on closed manifolds $Q= \int Tr(F)$ in 2d, $Q= \int Tr(F \wedge F)$ in 4d, etc, is defined. - On a subdivided manifold, it can be calculated in terms of the spaces of generalized connections associated to its pieces. Thus, spaces of boundary connections can be computed from spaces associated to faces. - The soul of our generalized connections is a notion of higher homotopy parallel transport defined for smooth connections. We recover standard generalized connections by forgetting its higher levels. - Higher levels of our higher gauge fields are often trivial. Then $\widetilde{\cal A}_\Sigma = \bar{\cal A}_\Sigma$ for $\dim \Sigma = 3$ and $G=SU(2)$, but $\widetilde{\cal A}_M \neq \bar{\cal A}_M$ for $\dim M = 4$ and $G=SL(2, {\mathbb C})$ or $G=SU(2)$. Boundary data for loop quantum gravity is consistent with our space of generalized connections, but a path integral for quantum gravity with Lorentzian or euclidean signatures would be sensitive to homotopy data.

There is no new related paper today

  1. [] - Title: Gravitational waves from black hole emission - Tousif Islam, Gaurav Khanna, Steven L. Liebling

Wed - 07/24/24

There is no new related paper today

There is no new related paper today

  1. [] - Title: Fractional Holographic Dark Energy - Oem Trivedi, Ayush Bidlan, Paulo Moniz

Tue - 07/23/24

**Title:

      Quantizing the Bosonic String on a Loop Quantum Gravity Background**  - **Authors:** Deepak Vaid, Luigi Teixeira de Sousa  - **Subjects:** Subjects: High Energy Physics - Theory (hep-th)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  With the goal of understanding whether or not it is possible to construct a string theory which is consistent with loop quantum gravity (LQG), we study alternate versions of the Nambu-Goto action for a bosonic string. We consider two types of modifications. The first is a phenomenological action based on the observation that LQG tells us that areas of two-surfaces are operators in quantum geometry and are bounded from below. This leads us to a string action which is similar to that of bimetric gravity. We provide formulations of the bimetric string for both the Nambu-Goto (second order) and Polyakov (first order) formulations. We explore the classical solutions of this action and its quantization and relate it to the conventional string solutions. The second is an action in which the background geometry is described in terms of the pullback of the connection which describes the bulk geometry to the worldsheet. The resulting action is in the form of a gauged sigma model, where the spacetime co-ordinates are now vectors which transform under $ISO(D,1)$. We find that for the particular case of a constant background connection the action reduces to the bimetric action discussed above. We discuss classical solutions and quantization strategies for this action and its implications for the broader program of unifying string theory and loop quantum gravity.

There is no new related paper today

Mon - 07/22/24

**Title:

      Quantizing the Bosonic String on a Loop Quantum Gravity Background**  - **Authors:** Deepak Vaid, Luigi Teixeira de Sousa  - **Subjects:** Subjects: High Energy Physics - Theory (hep-th)  - **Arxiv link:** [https://arxiv.org/abs/](https://arxiv.org/abs/)  - **Abstract**  With the goal of understanding whether or not it is possible to construct a string theory which is consistent with loop quantum gravity (LQG), we study alternate versions of the Nambu-Goto action for a bosonic string. We consider two types of modifications. The first is a phenomenological action based on the observation that LQG tells us that areas of two-surfaces are operators in quantum geometry and are bounded from below. This leads us to a string action which is similar to that of bimetric gravity. We provide formulations of the bimetric string for both the Nambu-Goto (second order) and Polyakov (first order) formulations. We explore the classical solutions of this action and its quantization and relate it to the conventional string solutions. The second is an action in which the background geometry is described in terms of the pullback of the connection which describes the bulk geometry to the worldsheet. The resulting action is in the form of a gauged sigma model, where the spacetime co-ordinates are now vectors which transform under $ISO(D,1)$. We find that for the particular case of a constant background connection the action reduces to the bimetric action discussed above. We discuss classical solutions and quantization strategies for this action and its implications for the broader program of unifying string theory and loop quantum gravity.

There is no new related paper today

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