scholarly journals Effective theories as truncated trans-series and scale separated compactifications

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Maxim Emelin
Keyword(s):  
Equations Of Motion ◽  
Effective Field ◽  
Effective Theory ◽  
Scaling Effects ◽  
De Sitter ◽  
Asymptotic Regime ◽  
De Sitter Vacua ◽  
The Right ◽  
Effective Theories ◽  
Quantum Equations

Abstract We study the possibility of realizing scale-separated type IIB Anti-de Sitter and de Sitter compactifications within a controlled effective field theory regime defined by low-energy and large (but scale-separated) compactification volume. The approach we use views effective theories as truncations of the full quantum equations of motion expanded in a trans-series around this asymptotic regime. By studying the scalings of all possible perturbative and non-perturbative corrections we identify the effects that have the right scaling to allow for the desired solutions. In the case of Anti-de Sitter, we find agreement with KKLT-type scenarios, and argue that non-perturbative brane-instantons wrapping four-cycles (or similarly scaling effects) are essentially the only ingredient that allows for scale separated solutions. We also comment on the relation of these results to the AdS swampland conjectures. For the de Sitter case we find that we are forced to introduce an infinite number of relatively unsuppressed corrections to the equations of motion, leading to a breakdown of effective theory. This suggests that if de Sitter vacua exist in the string landscape, they should not be thought of as residing within the same effective theory as the AdS or Minkowski compactifications, but rather as defining a separate asymptotic regime, presumably related to the others by a duality transformation.

scholarly journals de Sitter vacua from ten dimensions

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Shamit Kachru ◽  
Manki Kim ◽  
Liam McAllister ◽  
Max Zimet
Keyword(s):  
Equations Of Motion ◽  
Effective Theory ◽  
De Sitter ◽  
Stress Energy ◽  
Exact Agreement ◽  
De Sitter Vacua ◽  
Brane Action

Abstract We analyze the de Sitter construction of [1] using ten-dimensional supergravity, finding exact agreement with the four-dimensional effective theory. Starting from the fermionic couplings in the D7-brane action, we derive the ten-dimensional stress-energy due to gaugino condensation on D7-branes. We demonstrate that upon including this stress-energy, as well as that due to anti-D3-branes, the ten-dimensional equations of motion require the four-dimensional curvature to take precisely the value determined by the four-dimensional effective theory of [1].

scholarly journals MOND theory

2015 ◽  
Vol 93 (2) ◽  
pp. 107-118 ◽  
Author(s):  
Mordehai Milgrom
Keyword(s):  
Gravitational Lensing ◽  
Scale Invariance ◽  
Equations Of Motion ◽  
Effective Theory ◽  
Special Role ◽  
Scale Invariant ◽  
Limited Applicability ◽  
Total Action ◽  
General Aspects ◽  
Effective Theories

A general account of modified Newtonian dynamics (MOND) theory is given. I start with the basic tenets of MOND, which posit departure from standard dynamics in the limit of low acceleration — below an acceleration constant a0 — where dynamics become scale invariant. I list some of the salient predictions of these tenets. The special role of a0 and its significance are then discussed. In particular, I stress its coincidence with cosmologically relevant accelerations, which may point to MOND having deep interplay with cosmology. The deep-MOND limit and the consequences of its scale invariance are considered in some detail. There are many ways to achieve scale invariance of the equations of motion — guaranteed if the total action has a well-defined scaling dimension. The mere realization that this is enough to ensure MOND phenomenology opens a wide scope for constructing MOND theories. General aspects of MOND theories are then described, after which I list briefly presently known theories, both nonrelativistic and relativistic. With few exceptions, the construction of known, full-fledged theories follows the same rough pattern: they modify the gravitational action; hinge on a0; introduce, already at the level of the action, an interpolating function between the low and high accelerations; and they obey MOND requirements in the two opposite limits. These theories have much heuristic value as proofs of various concepts (e.g., that covariant MOND theories can be written with correct gravitational lensing). But, probably, none points to the final MOND theory. At best, they are effective theories of limited applicability. I argue that we have so far explored only a small corner of the space of possible MOND theories. I then outline several other promising approaches to constructing MOND theories that strive to obtain MOND as an effective theory from deeper concepts, for example, by modifying inertia and (or) gravity as a result of interactions with some omnipresent agent. These have made encouraging progress in various degrees, but have not yet resulted in full-fledged theories that can be applied to all systems and situations. Some of the presently known theories do enjoy a natural appearance of a cosmological-constant-like contribution that, furthermore, exhibits the observed connection with a0. However, none were shown to address fully the mass discrepancies in cosmology and structure formation that are otherwise explained by cosmological dark matter. This may well be due to our present ignorance of the true connections between MOND and cosmology. We have no clues as to whether and how MOND aspects enter nongravitational phenomena, but I discuss briefly some possibilities.

scholarly journals STRING QUANTIZATION IN CURVED SPACETIMES: NULL STRING APPROACH

1995 ◽  
Vol 10 (32) ◽  
pp. 2479-2484 ◽  
Author(s):  
H.J. DE VEGA ◽  
I. GIANNAKIS ◽  
A. NICOLAIDIS
Keyword(s):  
Equations Of Motion ◽  
Critical Dimension ◽  
String Tension ◽  
Conformal Anomaly ◽  
De Sitter ◽  
Gravitational Fields ◽  
First Order ◽  
Sitter Spacetime ◽  
The Right ◽  
Null String

We study quantum strings in strong gravitational fields. The relevant small parameter is [Formula: see text] where Rc is the curvature of the spacetime and T0 is the string tension. Within our systematic expansion we obtain to zeroth-order the null string (string with zero tension), while the first-order correction incorporates the string dynamics. We apply our formalism to quantum null strings in de Sitter spacetime. After a reparametrization of the worldsheet coordinates, the equations of motion are simplified. The quantum algebra generated by the constraints is considered, ordering the momentum operators to the right of the coordinate operators. No critical dimension appears. It is anticipated, however, that the conformal anomaly will appear when the first-order corrections proportional to T0, are introduced.

scholarly journals Effective Field Theory with Nambu–Goldstone Modes

2020 ◽  
pp. 137-219 ◽  
Author(s):  
Antonio Pich
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Dynamical Symmetry ◽  
New Physics ◽  
Effective Field ◽  
Low Energy ◽  
Effective Theory ◽  
Current Status ◽  
Symmetry Properties ◽  
Effective Theories

These lectures provide an introduction to the low-energy dynamics of Nambu–Goldstone fields, which associated with some spontaneous (or dynamical) symmetry breaking, using the powerful methods of effective field theory. The generic symmetry properties of these massless modes are described in detail and two very relevant phenomenological applications are worked out: chiral perturbation theory, the low-energy effective theory of QCD, and the (non-linear) electroweak effective theory. The similarities and differences between these two effective theories are emphasized, and their current status is reviewed. Special attention is given to the short-distance dynamical information encoded in the low-energy couplings of the effective Lagrangians. The successful methods developed in QCD could help us to uncover fingerprints of new physics scales from future measurements of the electroweak effective theory couplings.

scholarly journals Portal Effective Theories. A framework for the model independent description of light hidden sector interactions

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Chiara Arina ◽  
Jan Hajer ◽  
Philipp Klose
Keyword(s):  
Effective Field ◽  
Effective Theory ◽  
Charged Kaon ◽  
Kaon Decay ◽  
Fixed Target Experiments ◽  
Hidden Sector ◽  
Pseudoscalar Mesons ◽  
Light Scalar ◽  
Effective Theories ◽  
Matching Techniques

Abstract We present a framework for the construction of portal effective theory (PETs) that couple effective field theories of the Standard Model (SM) to light hidden messenger fields. Using this framework we construct electroweak and strong scale PETs that couple the SM to messengers carrying spin zero, one half, or one. The electroweak scale PETs encompass all portal operators up to dimension five, while the strong scale PETs additionally contain all portal operators of dimension six and seven that contribute at leading order to quark-flavour violating transitions. Using the strong scale PETs, we define a set of portal currents that couple hidden sectors to QCD, and construct portal chiral perturbation theory (χPTs) that relate these currents to the light pseudoscalar mesons. We estimate the coefficients of the portal χPT Lagrangian that are not fixed by SM observations using non-perturbative matching techniques and give a complete list of the resulting one- and two-meson portal interactions. From those, we compute transition amplitudes for three golden channels that are used in hidden sector searches at fixed target experiments: i) charged kaon decay into a charged pion and a spin zero messenger, ii) charged kaon decay into a charged lepton and a spin one half messenger, and iii) neutral pion decay into a photon and a spin one messenger. Finally, we compare these amplitudes to specific expressions for models featuring light scalar particles, axion-like particles, heavy neutral leptons, and dark photons.

scholarly journals Soft de Sitter Effective Theory

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Timothy Cohen ◽  
Daniel Green
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Density Fluctuations ◽  
Power Counting ◽  
Effective Theory ◽  
Quantum Evolution ◽  
De Sitter ◽  
Sitter Background ◽  
De Sitter Universe ◽  
Power Counting Scheme

Abstract Calculating the quantum evolution of a de Sitter universe on superhorizon scales is notoriously difficult. To address this challenge, we introduce the Soft de Sitter Effective Theory (SdSET). This framework holds for superhorizon modes whose comoving momentum is far below the UV scale, which is set by the inverse comoving horizon. The SdSET is formulated using the same approach that yields the Heavy Quark Effective Theory. The degrees of freedom that capture the long wavelength dynamics are identified with the growing and decaying solutions to the equations of motion. The operator expansion is organized using a power counting scheme, and loops can be regulated while respecting the low energy symmetries. For massive quantum fields in a fixed de Sitter background, power counting implies that all interactions beyond the horizon are irrelevant. Alternatively, if the fields are very light, the leading interactions are at most marginal, and resumming the associated logarithms using (dynamical) renormalization group techniques yields the evolution equation for canonical stochastic inflation. The SdSET is also applicable to models where gravity is dynamical, including inflation. In this case, diffeomorphism invariance ensures that all interactions are irrelevant, trivially implying the all-orders conservation of adiabatic density fluctuations and gravitational waves. We briefly touch on the application to slow-roll eternal inflation by identifying novel relevant operators. This work serves to demystify many aspects of perturbation theory outside the horizon, and has a variety of applications to problems of cosmological interest.

scholarly journals EFFECTIVE FIELD THEORY OF A LOCALLY NONCOMMUTATIVE SPACE–TIME AND EXTRA DIMENSIONS

2008 ◽  
Vol 23 (16n17) ◽  
pp. 2613-2633 ◽  
Author(s):  
B. MIRZA ◽  
M. ZAREI
Keyword(s):  
Effective Field Theory ◽  
Extra Dimensions ◽  
Effective Field ◽  
Point Of View ◽  
Effective Theory ◽  
Noncommutative Space ◽  
Higher Dimension ◽  
Full Theory ◽  
Energy Theory ◽  
Effective Theories

We assume that the noncommutativity starts to be visible continuously from a scale ΛNC. According to this assumption, a two-loop effective action is derived for noncommutative ϕ4 and ϕ3 theories from a Wilsonian point of view. We show that these effective theories are free of UV/IR mixing phenomena. We also investigate the positivity constraint on coefficients of higher dimension operators present in the effective theory. This constraint makes the low energy theory to be UV completion of a full theory. Finally, we discuss noncommutativity and extra dimensions. In our effective theories formulated on noncommutative extra dimensions, if the campactification scale Λc is less than the scale ΛNC, the theory will not suffer from UV/IR mixing.

scholarly journals New non-perturbative de Sitter vacua in α′-complete cosmology

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Carmen A. Núñez ◽  
Facundo Emanuel Rost
Keyword(s):  
Equations Of Motion ◽  
Generalized Equations ◽  
De Sitter ◽  
Scale Factors ◽  
Spatial Dimensions ◽  
Higher Derivatives ◽  
De Sitter Vacua ◽  
The Stability ◽  
Derivatives Of ◽  
Constant Dilaton

Abstract The α′-complete cosmology developed by Hohm and Zwiebach classifies the O(d, d; ℝ) invariant theories involving metric, b-field and dilaton that only depend on time, to all orders in α′. Some of these theories feature non-perturbative isotropic de Sitter vacua in the string frame, generated by the infinite number of higher-derivatives of O(d, d; ℝ) multiplets. Extending the isotropic ansatz, we construct stable and unstable non-perturbative de Sitter solutions in the string and Einstein frames. The generalized equations of motion admit new solutions, including anisotropic d + 1-dimensional metrics and non-vanishing b-field. In particular, we find dSn+1× Td−n geometries with constant dilaton, and also metrics with bounded scale factors in the spatial dimensions with non-trivial b-field. We discuss the stability and non-perturbative character of the solutions, as well as possible applications.

scholarly journals Sharpening the boundaries between flux landscape and swampland by tadpole charge

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Keiya Ishiguro ◽  
Hajime Otsuka
Keyword(s):  
Flux Compactifications ◽  
Scalar Potential ◽  
Low Energy ◽  
The Other ◽  
Effective Theory ◽  
Taylor Model ◽  
De Sitter ◽  
Cancellation Condition ◽  
Vacuum Structure ◽  
De Sitter Vacua

Abstract We investigate the vacuum structure of four-dimensional effective theory arising from Type IIB flux compactifications on a mirror of the rigid Calabi-Yau threefold, corresponding to a T-dual of the DeWolfe-Giryavets-Kachru-Taylor model in Type IIA flux compactifications. By analyzing the vacuum structure of this interesting corner of string landscape, it turns out that there exist perturbatively unstable de Sitter (dS) vacua in addition to supersymmetric and non-supersymmetric anti-de Sitter vacua. On the other hand, the stable dS vacua appearing in the low-energy effective action violate the tadpole cancellation condition, indicating a strong correlation between the existence of dS vacua and the flux-induced D3-brane charge (tadpole charge). We also find analytically that the tadpole charge constrained by the tadpole cancellation condition emerges in the scalar potential in a nontrivial way. Thus, the tadpole charge would restrict the existence of stable dS vacua, and this fact underlies the statement of the dS conjecture. Furthermore, our analytical and numerical results exhibit that distributions of $$ \mathcal{O}(1) $$ O 1 parameters in expressions of several swampland conjectures peak at specific values.

Effective Field Theory in Particle Physics and Cosmology

2020 ◽  
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Particle Physics ◽  
Large Scale ◽  
Effective Field ◽  
Effective Theory ◽  
Soft Collinear Effective Theory ◽  
Multiple Length Scales ◽  
Cosmological Observations ◽  
Standard Models

Effective field theory (EFT) is a general method for describing quantum systems with multiple-length scales in a tractable fashion. It allows us to perform precise calculations in established models (such as the standard models of particle physics and cosmology), as well as to concisely parametrize possible effects from physics beyond the standard models. EFTs have become key tools in the theoretical analysis of particle physics experiments and cosmological observations, despite being absent from many textbooks. This volume aims to provide a comprehensive introduction to many of the EFTs in use today, and covers topics that include large-scale structure, WIMPs, dark matter, heavy quark effective theory, flavour physics, soft-collinear effective theory, and more.

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