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James Alvey - One of the best experts on this subject based on the ideXlab platform.

  • constraints on Global Symmetry breaking in quantum gravity from cosmic birefringence measurements
    Physics Letters B, 2021
    Co-Authors: James Alvey, Miguel Escudero Abenza
    Abstract:

    Abstract All Global symmetries are expected to be explicitly broken by quantum gravitational effects, and yet may play an important role in Particle Physics and Cosmology. As such, any evidence for a well-preserved Global Symmetry would give insight into an important feature of gravity. We argue that a recently reported 2.4σ detection of cosmic birefringence in the Cosmic Microwave Background could be the first observational indication of a well-preserved (although spontaneously broken) Global Symmetry in nature. A compelling solution to explain this measurement is a very light pseudoscalar field that interacts with electromagnetism. In order for gravitational effects not to lead to large corrections to the mass of this scalar field, we show that the breaking of Global symmetries by gravity should be bounded above. Finally, we highlight that any bound of this type would have clear implications for the construction of theories of quantum gravity, as well as for many particle physics scenarios.

  • the axion quality problem Global Symmetry breaking and wormholes
    Journal of High Energy Physics, 2021
    Co-Authors: James Alvey, Miguel Escudero
    Abstract:

    Continuous Global symmetries are expected to be broken by gravity, which can lead to important phenomenological consequences. A prime example is the threat that this poses to the viability of the Peccei-Quinn solution to the strong CP problem. In this paper, we explore the impact of wormholes as a source of Global Symmetry breaking by gravity. We review the current status of wormholes and Global symmetries and note that, surprisingly, the axion has a quality problem within non-perturbative Einstein gravity. Although these wormholes lead to a large breaking of Global symmetries, we show that their effect is nonetheless relevant for the model building of gauge protected axions. We also find wormhole solutions within two scenarios: (i) an extended Global Symmetry group within Einstein gravity, and (ii) U(1) wormholes within the low-energy limit of an open String Theory. The former allows us to show that the concept of a Global Symmetry in General Relativity is somewhat ill-defined. The latter illustrates that for motivated values of the string coupling constant, axions appear to have a quality problem within the open String Theory we consider.

  • the axion quality problem Global Symmetry breaking and wormholes
    arXiv: High Energy Physics - Phenomenology, 2020
    Co-Authors: James Alvey, Miguel Escudero
    Abstract:

    Continuous Global symmetries are expected to be broken by gravity, which can lead to important phenomenological consequences. A prime example is the threat that this poses to the viability of the Peccei-Quinn solution to the strong CP problem. In this paper, we explore the impact of wormholes as a source of Global Symmetry breaking by gravity. We review the current status of wormholes and Global symmetries and note that, surprisingly, the axion has a quality problem within non-perturbative Einstein gravity. Although these wormholes lead to a large breaking of Global symmetries, we show that their effect is nonetheless relevant for the model building of gauge protected axions. We also find novel wormhole solutions within two scenarios: (i) an extended Global Symmetry group within Einstein gravity, and (ii) U(1) wormholes within the low energy limit of an open String Theory. The former allows us to show that the concept of a Global Symmetry in General Relativity is somewhat ill-defined. The latter illustrates that for motivated values of the string coupling constant, axions appear to have a quality problem within the open String Theory we consider.

Miguel Escudero - One of the best experts on this subject based on the ideXlab platform.

  • the axion quality problem Global Symmetry breaking and wormholes
    Journal of High Energy Physics, 2021
    Co-Authors: James Alvey, Miguel Escudero
    Abstract:

    Continuous Global symmetries are expected to be broken by gravity, which can lead to important phenomenological consequences. A prime example is the threat that this poses to the viability of the Peccei-Quinn solution to the strong CP problem. In this paper, we explore the impact of wormholes as a source of Global Symmetry breaking by gravity. We review the current status of wormholes and Global symmetries and note that, surprisingly, the axion has a quality problem within non-perturbative Einstein gravity. Although these wormholes lead to a large breaking of Global symmetries, we show that their effect is nonetheless relevant for the model building of gauge protected axions. We also find wormhole solutions within two scenarios: (i) an extended Global Symmetry group within Einstein gravity, and (ii) U(1) wormholes within the low-energy limit of an open String Theory. The former allows us to show that the concept of a Global Symmetry in General Relativity is somewhat ill-defined. The latter illustrates that for motivated values of the string coupling constant, axions appear to have a quality problem within the open String Theory we consider.

  • the axion quality problem Global Symmetry breaking and wormholes
    arXiv: High Energy Physics - Phenomenology, 2020
    Co-Authors: James Alvey, Miguel Escudero
    Abstract:

    Continuous Global symmetries are expected to be broken by gravity, which can lead to important phenomenological consequences. A prime example is the threat that this poses to the viability of the Peccei-Quinn solution to the strong CP problem. In this paper, we explore the impact of wormholes as a source of Global Symmetry breaking by gravity. We review the current status of wormholes and Global symmetries and note that, surprisingly, the axion has a quality problem within non-perturbative Einstein gravity. Although these wormholes lead to a large breaking of Global symmetries, we show that their effect is nonetheless relevant for the model building of gauge protected axions. We also find novel wormhole solutions within two scenarios: (i) an extended Global Symmetry group within Einstein gravity, and (ii) U(1) wormholes within the low energy limit of an open String Theory. The former allows us to show that the concept of a Global Symmetry in General Relativity is somewhat ill-defined. The latter illustrates that for motivated values of the string coupling constant, axions appear to have a quality problem within the open String Theory we consider.

Edgar Shaghoulian - One of the best experts on this subject based on the ideXlab platform.

  • Global Symmetry euclidean gravity and the black hole information problem
    Journal of High Energy Physics, 2021
    Co-Authors: Daniel Harlow, Edgar Shaghoulian
    Abstract:

    In this paper we argue for a close connection between the non-existence of Global symmetries in quantum gravity and a unitary resolution of the black hole information problem. In particular we show how the essential ingredients of recent calculations of the Page curve of an evaporating black hole can be used to generalize a recent argument against Global symmetries beyond the AdS/CFT correspondence to more realistic theories of quantum gravity. We also give several low-dimensional examples of quantum gravity theories which do not have a unitary resolution of the black hole information problem in the usual sense, and which therefore can and do have Global symmetries. Motivated by this discussion, we conjecture that in a certain sense Euclidean quantum gravity is equivalent to holography.

Alessandro Vichi - One of the best experts on this subject based on the ideXlab platform.

  • charting the space of 3d cfts with a continuous Global Symmetry
    Journal of High Energy Physics, 2019
    Co-Authors: Joao Penedones, Anatoly Dymarsky, Emilio Trevisani, Alessandro Vichi
    Abstract:

    We study correlation functions of a conserved spin-1 current Jμ in three dimensional Conformal Field Theories (CFTs). We investigate the constraints imposed by permutation Symmetry and current conservation on the form of three point functions $$ \left\langle {J}_{\mu }{J}_{\nu }{\mathcal{O}}_{\Delta, \ell}\right\rangle $$ and the four point function 〈JμJνJρJσ〉 and identify the minimal set of independent crossing Symmetry conditions. We obtain a recurrence relation for conformal blocks for generic spin-1 operators in three dimensions. In the process, we improve several technical points, facilitating the use of recurrence relations. By applying the machinery of the numerical conformal bootstrap we obtain universal bounds on the dimensions of certain light operators as well as the central charge. Highlights of our results include numerical evidence for the conformal collider bound and new constraints on the parameters of the critical O(2) model. The results obtained in this work apply to any unitary, three dimensional CFT.

  • charting the space of 3d cfts with a continuous Global Symmetry
    arXiv: High Energy Physics - Theory, 2017
    Co-Authors: Anatoly Dymarsky, Joao Penedones, Emilio Trevisani, Alessandro Vichi
    Abstract:

    We study correlation functions of a conserved spin-1 current $J_\mu$ in three dimensional Conformal Field Theories (CFTs). We investigate the constraints imposed by permutation Symmetry and current conservation on the form of three point functions $\langle J_\mu J_\nu \mathcal O_{\Delta,\ell}\rangle $ and the four point function $\langle J_\mu J_\nu J_\rho J_\sigma \rangle $ and identify the minimal set of independent crossing Symmetry conditions. We obtain a recurrence relation for conformal blocks for generic spin-1 operators in three dimensions. In the process, we improve several technical points, facilitating the use of recurrence relations. By applying the machinery of the numerical conformal bootstrap we obtain universal bounds on the dimensions of certain light operators as well as the central charge. Highlights of our results include numerical evidence for the conformal collider bound and new constraints on the parameters of the critical $O(2)$ model. The results obtained in this work apply to any unitary, parity-preserving three dimensional CFT.

  • bounds in 4d conformal field theories with Global Symmetry
    Journal of Physics A, 2011
    Co-Authors: Riccardo Rattazzi, Slava Rychkov, Alessandro Vichi
    Abstract:

    We explore the constraining power of OPE associativity in 4D conformal field theory with a continuous Global Symmetry group. We give a general analysis of crossing Symmetry constraints in the 4-point function , where phi is a primary scalar operator in a given representation R. These constraints take the form of 'vectorial sum rules' for conformal blocks of operators whose representations appear in R circle times R and R circle times (R) over bar. The coefficients in these sum rules are related to the Fierz transformation matrices for the R circle times R circle times (R) over bar circle times (R) over bar invariant tensors. We show that the number of equations is always equal to the number of Symmetry channels to be constrained. We also analyze in detail two cases-the fundamental of SO(N) and the fundamental of SU(N). We derive the vectorial sum rules explicitly, and use them to study the dimension of the lowest singlet scalar in the phi x phi(dagger) OPE. We prove the existence of an upper bound on the dimension of this scalar. The bound depends on the conformal dimension of phi and approaches 2 in the limit dim(phi) -> 1. For several small groups, we compute the behavior of the bound at dim(phi) > 1. We discuss implications of our bound for the conformal technicolor scenario of electroweak Symmetry breaking.

  • bounds in 4d conformal field theories with Global Symmetry
    arXiv: High Energy Physics - Theory, 2010
    Co-Authors: Riccardo Rattazzi, Slava Rychkov, Alessandro Vichi
    Abstract:

    We explore the constraining power of OPE associativity in 4D Conformal Field Theory with a continuous Global Symmetry group. We give a general analysis of crossing Symmetry constraints in the 4-point function , where Phi is a primary scalar operator in a given representation R. These constraints take the form of 'vectorial sum rules' for conformal blocks of operators whose representations appear in R x R and R x Rbar. The coefficients in these sum rules are related to the Fierz transformation matrices for the R x R x Rbar x Rbar invariant tensors. We show that the number of equations is always equal to the number of Symmetry channels to be constrained. We also analyze in detail two cases - the fundamental of SO(N) and the fundamental of SU(N). We derive the vectorial sum rules explicitly, and use them to study the dimension of the lowest singlet scalar in the Phi x Phi* OPE. We prove the existence of an upper bound on the dimension of this scalar. The bound depends on the conformal dimension of Phi and approaches 2 in the limit dim(Phi)-->1. For several small groups, we compute the behavior of the bound at dim(Phi)>1. We discuss implications of our bound for the Conformal Technicolor scenario of electroweak Symmetry breaking.

Hee Cheol Kim - One of the best experts on this subject based on the ideXlab platform.

  • compactifications of ade conformal matter on a torus
    Journal of High Energy Physics, 2018
    Co-Authors: Hee Cheol Kim, Cumrun Vafa, Shlomo S Razamat, Gabi Zafrir
    Abstract:

    In this paper we study compactifications of ADE type conformal matter, N M5 branes probing ADE singularity, on torus with flux for Global Symmetry. We systematically construct the four dimensional theories by first going to five dimensions and studying interfaces. We claim that certain interfaces can be associated with turning on flux in six dimensions. The interface models when compactified on a circle comprise building blocks for constructing four dimensional models associated to flux compactifications of six dimensional theories on a torus. The theories in four dimensions turn out to be quiver gauge theories and the construction implies many interesting cases of IR Symmetry enhancements and dualities of such theories.

  • 5-dim superconformal index with enhanced E _ n Global Symmetry
    Journal of High Energy Physics, 2012
    Co-Authors: Hee Cheol Kim, Sung-soo Kim, Kimyeong Lee
    Abstract:

    A bstractThe five-dimensional $ \mathcal{N}=1 $ supersymmetric gauge theory with Sp( N ) gauge group and SO(2 N _ f ) flavor Symmetry describes the physics on N D4-branes with N _ f D8-branes on top of a single O8 orientifold plane in Type I′ theory. This theory is known to be superconformal at the strong coupling limit with the enhanced Global Symmetry $ {E_{{N_f +1}}} $ for N _ f ≤ 7. In this work we calculate the superconformal index on S ^1 × S ^4 for the Sp(1) gauge theory by the localization method and confirm such enhancement of the Global Symmetry at the superconformal limit for N _ f ≤ 5 to a few leading orders in the chemical potential. Both perturbative and (anti)instanton contributions are present in this calculation. For N _ f = 6, 7 cases some issues related the pole structure of the instanton calculation could not be resolved and here we could provide only some suggestive answer for the leading contributions to the index. For the Sp( N ) case, similar issues related to the pole structure appear.

  • 5 dim superconformal index with enhanced en Global Symmetry
    arXiv: High Energy Physics - Theory, 2012
    Co-Authors: Hee Cheol Kim, Sung-soo Kim, Kimyeong Lee
    Abstract:

    The five-dimensional $\mathcal{N}=1$ supersymmetric gauge theory with Sp(N) gauge group and SO(2N_f) flavor Symmetry describes the physics on N D4-branes with $N_f$ D8-branes on top of a single O8 orientifold plane in Type I' theory. This theory is known to be superconformal at the strong coupling limit with the enhanced Global Symmetry $E_{N_f+1}$ for $N_f\le 7$. In this work we calculate the superconformal index on $S^1\times S^4$ for the Sp(1) gauge theory by the localization method and confirm such enhancement of the Global Symmetry at the superconformal limit for $N_f\le 5$ to a few leading orders in the chemical potential. Both perturbative and (anti)instanton contributions are present in this calculation. For $N_f=6,7$ cases some issues related the pole structure of the instanton calculation could not be resolved and here we could provide only some suggestive answer for the leading contributions to the index. For the Sp(N) case, similar issues related to the pole structure appear.