scholarly journals Closed strings and weak gravity from higher-spin causality

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Jared Kaplan ◽  
Sandipan Kundu
Keyword(s):  
Planck Scale ◽  
Closed String ◽  
Spin States ◽  
Quantum Field ◽  
Spin Particle ◽  
Regge Trajectories ◽  
Gravity Condition ◽  
Weakly Coupled ◽  
Higher Spin ◽  
Weak Gravity

Abstract We combine old and new quantum field theoretic arguments to show that any theory of stable or metastable higher spin particles can be coupled to gravity only when the gravity sector has a stringy structure. Metastable higher spin particles, free or interacting, cannot couple to gravity while preserving causality unless there exist higher spin states in the gravitational sector much below the Planck scale Mpl. We obtain an upper bound on the mass Λgr of the lightest higher spin particle in the gravity sector in terms of quantities in the non-gravitational sector. We invoke the CKSZ uniqueness theorem to argue that any weakly coupled UV completion of such a theory must have a gravity sector containing infinite towers of asymptotically parallel, equispaced, and linear Regge trajectories. Consequently, gravitational four-point scattering amplitudes must coincide with the closed string four-point amplitude for s, t ≫ 1, identifying Λgr as the string scale. Our bound also implies that all metastable higher spin particles in 4d with masses m ≪ Λgr must satisfy a weak gravity condition.

scholarly journals The Weak Gravity Conjecture and axion strings

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Ben Heidenreich ◽  
Matthew Reece ◽  
Tom Rudelius
Keyword(s):  
Gauge Theory ◽  
High Spin ◽  
Planck Scale ◽  
Mass Scale ◽  
Spin States ◽  
High Spin States ◽  
Weakly Coupled ◽  
Klein Theory ◽  
Weak Gravity ◽  
Kaluza Klein

Abstract Strong (sublattice or tower) formulations of the Weak Gravity Conjecture (WGC) imply that, if a weakly coupled gauge theory exists, a tower of charged particles drives the theory to strong coupling at an ultraviolet scale well below the Planck scale. This tower can consist of low-spin states, as in Kaluza-Klein theory, or high-spin states, as with weakly-coupled strings. We provide a suggestive bottom-up argument based on the mild p-form WGC that, for any gauge theory coupled to a fundamental axion through a θF ∧ F term, the tower is a stringy one. The charge-carrying string states at or below the WGC scale gMPl are simply axion strings for θ, with charged modes arising from anomaly inflow. Kaluza-Klein theories evade this conclusion and postpone the appearance of high-spin states to higher energies because they lack a θF ∧ F term. For abelian Kaluza-Klein theories, modified arguments based on additional abelian groups that interact with the Kaluza-Klein gauge group sometimes pinpoint a mass scale for charged strings. These arguments reinforce the Emergent String and Distant Axionic String Conjectures. We emphasize the unproven assumptions and weak points of the arguments, which provide interesting targets for further work. In particular, a sharp characterization of when gauge fields admit θF ∧ F couplings and when they do not would be immensely useful for particle phenomenology and for clarifying the implications of the Weak Gravity Conjecture.

Weakly coupled gravity beyond general relativity

2015 ◽  
Vol 24 (12) ◽  
pp. 1544031 ◽  
Author(s):  
Xián O. Camanho ◽  
José D. Edelstein ◽  
Alexander Zhiboedov
Keyword(s):  
General Relativity ◽  
Time Delay ◽  
Wave Spectrum ◽  
Riemann Tensor ◽  
Spin States ◽  
Causality Violation ◽  
Novel Structure ◽  
Weakly Coupled ◽  
Point Vertex ◽  
Higher Spin

We explore four-dimensional (4D) weakly coupled gravity beyond general relativity in an on-shell language, focusing on the graviton three-point vertex. This admits a novel structure which can be attributed to a term cubic in the Riemann tensor. We consider a generalization of the Shapiro time delay experiment that involves polarized gravitons and show that the new vertex leads to causality violation. Fixing the problem demands the inclusion of an infinite tower of massive higher spin states. Perturbative string theory provides an example of this phenomenon, the only known so far. Interestingly enough, the same argument being applied to inflation suggests that stringy signatures may be hidden in the non-Gaussianities of the primordial gravity wave spectrum.

scholarly journals Spiky strings in de Sitter space

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Mitsuhiro Kato ◽  
Kanji Nishii ◽  
Toshifumi Noumi ◽  
Toshiaki Takeuchi ◽  
Siyi Zhou
Keyword(s):  
Regge Trajectory ◽  
Flat Space ◽  
De Sitter Space ◽  
High Energy ◽  
Spin States ◽  
De Sitter ◽  
Regge Trajectories ◽  
Higher Spin ◽  
Maximum Spin

Abstract We study semiclassical spiky strings in de Sitter space and the corresponding Regge trajectories, generalizing the analysis in anti-de Sitter space. In particular we demonstrate that each Regge trajectory has a maximum spin due to de Sitter acceleration, similarly to the folded string studied earlier. While this property is useful for the spectrum to satisfy the Higuchi bound, it makes a nontrivial question how to maintain mildness of high-energy string scattering which we are familiar with in flat space and anti-de Sitter space. Our analysis implies that in order to have infinitely many higher spin states, one needs to consider infinitely many Regge trajectories with an increasing folding number.

scholarly journals Trace dynamics and division algebras: towards quantum gravity and unification

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Tejinder P. Singh
Keyword(s):  
Lie Group ◽  
Planck Scale ◽  
The Self ◽  
Division Algebras ◽  
Quantum Field ◽  
Octonion Algebra ◽  
Gauge Transformations ◽  
Yang Mills ◽  
Massless Spin ◽  
Correct Understanding

AbstractWe have recently proposed a Lagrangian in trace dynamics at the Planck scale, for unification of gravitation, Yang–Mills fields, and fermions. Dynamical variables are described by odd-grade (fermionic) and even-grade (bosonic) Grassmann matrices. Evolution takes place in Connes time. At energies much lower than Planck scale, trace dynamics reduces to quantum field theory. In the present paper, we explain that the correct understanding of spin requires us to formulate the theory in 8-D octonionic space. The automorphisms of the octonion algebra, which belong to the smallest exceptional Lie group G2, replace space-time diffeomorphisms and internal gauge transformations, bringing them under a common unified fold. Building on earlier work by other researchers on division algebras, we propose the Lorentz-weak unification at the Planck scale, the symmetry group being the stabiliser group of the quaternions inside the octonions. This is one of the two maximal sub-groups of G2, the other one being SU(3), the element preserver group of octonions. This latter group, coupled with U(1)em, describes the electrocolour symmetry, as shown earlier by Furey. We predict a new massless spin one boson (the ‘Lorentz’ boson) which should be looked for in experiments. Our Lagrangian correctly describes three fermion generations, through three copies of the group G2, embedded in the exceptional Lie group F4. This is the unification group for the four fundamental interactions, and it also happens to be the automorphism group of the exceptional Jordan algebra. Gravitation is shown to be an emergent classical phenomenon. Although at the Planck scale, there is present a quantised version of the Lorentz symmetry, mediated by the Lorentz boson, we argue that at sub-Planck scales, the self-adjoint part of the octonionic trace dynamics bears a relationship with string theory in 11 dimensions.

scholarly journals Towards causal patch physics in dS/CFT

2018 ◽  
Vol 168 ◽  
pp. 01007 ◽  
Author(s):  
Yasha Neiman
Keyword(s):  
Field Theory ◽  
Higher Spin Gravity ◽  
De Sitter Space ◽  
Vector Model ◽  
Status Report ◽  
Quantum Field ◽  
Cosmological Horizon ◽  
De Sitter ◽  
Higher Spin ◽  
Holographic Description

This contribution is a status report on a research program aimed at obtaining quantum-gravitational physics inside a cosmological horizon through dS/CFT, i.e. through a holographic description at past/future infinity of de Sitter space. The program aims to bring together two main elements. The first is the observation by Anninos, Hartman and Strominger that Vasiliev’s higher-spin gravity provides a working model for dS/CFT in 3+1 dimensions. The second is the proposal by Parikh, Savonije and Verlinde that dS/CFT may prove more tractable if one works in so-called “elliptic” de Sitter space – a folded-in-half version of global de Sitter where antipodal points have been identified. We review some relevant progress concerning quantum field theory on elliptic de Sitter space, higher-spin gravity and its holographic duality with a free vector model. We present our reasons for optimism that the approach outlined here will lead to a full holographic description of quantum (higher-spin) gravity in the causal patch of a de Sitter observer.

Manifest non-locality in quantum mechanics, quantum field theory and quantum gravity

2019 ◽  
Vol 34 (28) ◽  
pp. 1941004
Author(s):  
Laurent Freidel ◽  
Robert G. Leigh ◽  
Djordje Minic
Keyword(s):  
Quantum Theory ◽  
String Theory ◽  
Quantum Gravity ◽  
Closed String ◽  
Covariant Formulation ◽  
Quantum Field ◽  
Quantum Geometry ◽  
Local Quantum ◽  
Generic Representation ◽  
Non Locality

We summarize our recent work on the foundational aspects of string theory as a quantum theory of gravity. We emphasize the hidden quantum geometry (modular spacetime) behind the generic representation of quantum theory and then stress that the same geometric structure underlies a manifestly T-duality covariant formulation of string theory, that we call metastring theory. We also discuss an effective non-commutative description of closed strings implied by intrinsic non-commutativity of closed string theory. This fundamental non-commutativity is explicit in the metastring formulation of quantum gravity. Finally we comment on the new concept of metaparticles inherent to such an effective non-commutative description in terms of bi-local quantum fields.

scholarly journals Sequential magnetotunneling in a vertical quantum dot tuned at the crossing to higher spin states

2000 ◽  
Vol 61 (15) ◽  
pp. 10242-10246 ◽  
Author(s):  
B. Jouault ◽  
G. Santoro ◽  
A. Tagliacozzo
Keyword(s):  
Quantum Dot ◽  
Spin States ◽  
Higher Spin

SOLITONS EXPERIENCE FOR BLACK HOLE PRODUCTION IN ULTRARELATIVISTIC PARTICLE COLLISIONS

2012 ◽  
Vol 26 (27n28) ◽  
pp. 1243010 ◽  
Author(s):  
I. YA. AREF'EVA
Keyword(s):  
Black Hole ◽  
Scattering Amplitudes ◽  
Planck Scale ◽  
Functional Integral ◽  
Quantum Field ◽  
Mass Energy ◽  
Particle Collisions ◽  
Functional Integral Method ◽  
Geometrical Cross Section ◽  
Current Paradigm

We discuss the analogy between soliton scattering in quantum field theory and black hole/wormholes (BH/WH) production in ultrarelativistic particle collisions in gravity. It is a common wisdom of the current paradigm suggests that BH/WH formation in particles collisions will happen when a center-mass energy of colliding particles is sufficiently above the Planck scale (the transplanckian region) and the BH/WH production can be estimated by the classical geometrical cross section. We compare the background of this paradigm with the functional integral method to scattering amplitudes and, in particular, we stress the analogy of the BH production in collision of ultrarelativistic particle and appearance of breathers poles in the scattering amplitudes in the Sin–Gordon model.

Study of antimagnetic rotation in 109,111Cd

2018 ◽  
Vol 27 (04) ◽  
pp. 1850034 ◽  
Author(s):  
C. Majumder ◽  
H. P. Sharma ◽  
S. Chakraborty ◽  
S. S. Tiwary
Keyword(s):  
Electric Quadrupole ◽  
Negative Parity ◽  
Spin States ◽  
Transition Rates ◽  
Quadrupole Transition ◽  
Semiclassical Model ◽  
Electric Quadrupole Transition ◽  
Higher Spin ◽  
Antimagnetic Rotation ◽  
Dynamic Moment

The reduced electric quadrupole transition rates have been calculated for the states of the negative parity bands in [Formula: see text]Cd nuclei using semiclassical model (SCM). The calculated transition rates are found to be decreasing with increasing spin for the states above [Formula: see text] and the dynamic moment of inertia [Formula: see text] of the higher spin states are found to be almost constant. The calculated B(E2) values show better agreement with the experimental B(E2) values for [Formula: see text]Cd. The results for both [Formula: see text]Cd and [Formula: see text]Cd nuclei show a very rapidly increasing value of the [Formula: see text] ratio with increasing spin, suggesting the antimagnetic rotational character of the states lying above the spins [Formula: see text] and [Formula: see text], respectively.

scholarly journals Axion experiments to algebraic geometry: Testing quantum gravity via the Weak Gravity Conjecture

2016 ◽  
Vol 25 (12) ◽  
pp. 1643005 ◽  
Author(s):  
Ben Heidenreich ◽  
Matthew Reece ◽  
Tom Rudelius
Keyword(s):  
Field Theory ◽  
Algebraic Geometry ◽  
Quantum Gravity ◽  
General Nature ◽  
Quantum Field ◽  
Gauge Groups ◽  
Common Features ◽  
Conformal Field ◽  
Pure Mathematics ◽  
Weak Gravity

Common features of known quantum gravity theories may hint at the general nature of quantum gravity. The absence of continuous global symmetries is one such feature. This inspired the Weak Gravity Conjecture, which bounds masses of charged particles. We propose the Lattice Weak Gravity Conjecture, which further requires the existence of an infinite tower of particles of all possible charges under both abelian and nonabelian gauge groups and directly implies a cutoff for quantum field theory. It holds in a wide variety of string theory examples and has testable consequences for the real world and for pure mathematics. We sketch some implications of these ideas for models of inflation, for the QCD axion (and LIGO), for conformal field theory, and for algebraic geometry.

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