scholarly journals Worldsheets in holography: Computing corrections to the Veneziano amplitude

2019 ◽  
Vol 34 (14) ◽  
pp. 1930002
Author(s):  
Edwin Ireson
Keyword(s):  
Effective Field Theory ◽  
Scattering Amplitude ◽  
Broad Class ◽  
Effective Field ◽  
Wilson Loops ◽  
Veneziano Amplitude ◽  
Interaction Picture ◽  
Strongly Coupled ◽  
Expectation Value ◽  
String Worldsheet

We provide a brief summary of a method to calculate improvements to the Veneziano amplitude, creating sub-leading nonlinearities in the Regge trajectory of states. We formulate it as an extension of a computation by Makeenko and Olesen. We begin in a confining gauge theory coupled to matter, rewriting the meson scattering amplitude as a specific path integral over shapes and sizes of closed Wilson loops using the worldline formalism. We then prescribe how to further the computation at strong coupling by employing holography, which provides a prescription for the expectation value of these Wilson loops in strongly coupled regimes. The computation we desire then appears to subsume to a certain calculation in the effective field theory of a string worldsheet embedded in a certain broad class of allowed holographic backgrounds. A convenient interaction picture presents itself naturally in this context, allowing us to draw Feynman diagrams corresponding to the first few corrections due to weaker coupling regimes. The answer we find has qualitatively the same features as other endeavors with the same objective.

scholarly journals Vacuum Constraints for Realistic Strongly Coupled Heterotic M-Theories

Symmetry ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 723
Author(s):  
Burt Ovrut
Keyword(s):  
Field Theory ◽  
Vector Bundle ◽  
Domain Wall ◽  
Effective Field Theory ◽  
Effective Field ◽  
Anomaly Cancellation ◽  
Strongly Coupled ◽  
Hidden Sector ◽  
M Theory ◽  
Bulk Space

The compactification from the 11-dimensional Horava-Witten orbifold to 5-dimensional heterotic M-theory on a Schoen Calabi-Yau threefold is reviewed, as is the specific S U ( 4 ) vector bundle leading to the “heterotic standard model” in the observable sector. A generic formalism for a consistent hidden sector gauge bundle, within the context of strongly coupled heterotic M-theory, is presented. Anomaly cancellation and the associated bulk space 5-branes are discussed in this context. The further compactification to a 4-dimensional effective field theory on a linearized BPS double domain wall is then presented to order κ 11 4 / 3 . Specifically, the generic constraints required for anomaly cancellation and by the linearized domain wall solution, restrictions imposed by the vanishing of the D-terms and, finally, the constraints imposed by the necessity for positive, perturbative squared gauge couplings to this order are presented in detail.

scholarly journals Heavy hybrids and tetraquarks in effective field theory

2019 ◽  
Vol 202 ◽  
pp. 01005 ◽  
Author(s):  
Jaume Tarrús Castellà
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Bound States ◽  
Heavy Meson ◽  
Effective Field ◽  
Full Description ◽  
Wilson Loops ◽  
Inclusive Decays ◽  
Lattice Calculations

We report on an effective field theory (EFT) description of exotic quarkonia as bound states on the spectrum of hybrid and tetraquarks static energies. We provide expressions for hybrid and tetraquarks static energies in terms of Wilson loops. The former have been computed in quenched lattice calculations but the latter are yet unavailable. From the few simulations with dynamical light-quarks we argue that the overall picture from hybrid static energies does not change but additional states, such as heavy meson pairs, need to be considered for a full description. In this EFT framework for quarkonium hybrids, we report on recent results for mixing with standard quarkonium, spin-dependent contributions, and semi-inclusive decays.

scholarly journals New positivity bounds from full crossing symmetry

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Andrew J. Tolley ◽  
Zi-Yue Wang ◽  
Shuang-Yong Zhou
Keyword(s):  
Field Theory ◽  
Dispersion Relation ◽  
Effective Field Theory ◽  
Scattering Amplitude ◽  
Effective Field ◽  
Field Theories ◽  
Upper And Lower Bounds ◽  
Chiral Perturbation ◽  
Partial Wave Expansion ◽  
Crossing Symmetry

Abstract Positivity bounds are powerful tools to constrain effective field theories. Utilizing the partial wave expansion in the dispersion relation and the full crossing symmetry of the scattering amplitude, we derive several sets of generically nonlinear positivity bounds for a generic scalar effective field theory: we refer to these as the P Q, Dsu, Dstu and $$ {\overline{D}}^{\mathrm{stu}} $$ D ¯ stu bounds. While the PQ bounds and Dsu bounds only make use of the s↔u dispersion relation, the Dstu and $$ {\overline{D}}^{\mathrm{stu}} $$ D ¯ stu bounds are obtained by further imposing the s↔t crossing symmetry. In contradistinction to the linear positivity for scalars, these inequalities can be applied to put upper and lower bounds on Wilson coefficients, and are much more constraining as shown in the lowest orders. In particular we are able to exclude theories with soft amplitude behaviour such as weakly broken Galileon theories from admitting a standard UV completion. We also apply these bounds to chiral perturbation theory and we find these bounds are stronger than the previous bounds in constraining its Wilson coefficients.

scholarly journals Gapped Goldstones at the cut-off scale: a non-relativistic EFT

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
G. Cuomo ◽  
A. Esposito ◽  
E. Gendy ◽  
A. Khmelnitsky ◽  
A. Monin ◽  
...  
Keyword(s):  
Effective Field Theory ◽  
Chemical Potential ◽  
Effective Field ◽  
Energy Scale ◽  
Field Theories ◽  
Conformal Field Theories ◽  
Strongly Coupled ◽  
Conformal Field ◽  
Charge Sector ◽  
Large Charge

Abstract At finite density, the spontaneous breakdown of an internal non-Abelian symmetry dictates, along with gapless modes, modes whose gap is fixed by the algebra and proportional to the chemical potential: the gapped Goldstones. Generically the gap of these states is comparable to that of other non-universal excitations or to the energy scale where the dynamics is strongly coupled. This makes it non-straightforward to derive a universal effective field theory (EFT) description realizing all the symmetries. Focusing on the illustrative example of a fully broken SU(2) group, we demonstrate that such an EFT can be constructed by carving out around the Goldstones, gapless and gapped, at small 3-momentum. The rules governing the EFT, where the gapless Goldstones are soft while the gapped ones are slow, are those of standard nonrelativistic EFTs, like for instance nonrelativistic QED. In particular, the EFT Lagrangian formally preserves gapped Goldstone number, and processes where such number is not conserved are described inclusively by allowing for imaginary parts in the Wilson coefficients. Thus, while the symmetry is manifestly realized in the EFT, unitarity is not. We comment on the application of our construction to the study of the large charge sector of conformal field theories with non-Abelian symmetries.

scholarly journals The $${\varvec{\Lambda (1405)}}$$ in resummed chiral effective field theory

2021 ◽  
Vol 81 (7) ◽  
Author(s):  
Xiu-Lei Ren ◽  
E. Epelbaum ◽  
J. Gegelia ◽  
U.-G. Meißner
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Scattering Amplitude ◽  
Effective Field ◽  
Leading Order ◽  
Chiral Effective Field Theory ◽  
Higher Order Terms ◽  
Invariant Formulation ◽  
Pole Structure ◽  
Coupled Channel

AbstractWe study the unitarized meson–baryon scattering amplitude at leading order in the strangeness $$S=-1$$ S = - 1 sector using time-ordered perturbation theory for a manifestly Lorentz-invariant formulation of chiral effective field theory. By solving the coupled-channel integral equations with the full off-shell dependence of the effective potential and applying subtractive renormalization, we analyze the renormalized scattering amplitudes and obtain the two-pole structure of the $$\Lambda (1405)$$ Λ ( 1405 ) resonance. We also point out the necessity of including higher-order terms.

Searching for composite Higgs models at the LHC

2016 ◽  
Vol 31 (19) ◽  
pp. 1630026
Author(s):  
Thomas Flacke
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Bound States ◽  
Effective Field ◽  
Theory Approach ◽  
Electroweak Symmetry ◽  
Hierarchy Problem ◽  
Strongly Coupled ◽  
Goldstone Bosons ◽  
Composite Higgs

Composite Higgs models have the potential to provide a solution to the hierarchy problem and a dynamical explanation for the generation of the Higgs potential. They can be tested at the LHC as the new sector which underlies electroweak symmetry breaking must become strong in the TeV regime, which implies additional bound states beyond the Higgs. In this paper, we first discuss prospects and search strategies for top partners (and other quark partners) in the strongly coupled sector, which we study in an effective field theory setup. In the second part of the proceedings, we go beyond the effective field theory approach. We discuss potential UV embeddings for composite Higgs models which contain a Higgs as well as top partners. We show that in all of these models, additional pseudo-Nambu–Goldstone bosons beyond the Higgs are present. In particular, all of the models contain a pseudoscalar which couples to the Standard Model gauge fields through Wess–Zumino–Witten terms, providing a prime candidate for a di-boson (including a di-photon) resonance. The models also contain colored pNGBs which can be searched for at the LHC.

scholarly journals Expectation management

2021 ◽  
Vol 81 (6) ◽  
Author(s):  
Johannes Braathen ◽  
Mark D. Goodsell ◽  
Sebastian Paßehr ◽  
Emanuelle Pinsard
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
Standard Treatment ◽  
Effective Field ◽  
Beyond The Standard Model ◽  
Quartic Coupling ◽  
Expectation Value ◽  
The Standard Model ◽  
Expectation Management

AbstractWe consider the application of a Fleischer–Jegerlehner-like treatment of tadpoles to the calculation of neutral scalar masses (including the Higgs) in general theories beyond the Standard Model. This is especially useful when the theory contains new scalars associated with a small expectation value, but comes with its own disadvantages. We show that these can be overcome by combining with effective field theory matching. We provide the formalism in this modified approach for matching the quartic coupling of the Higgs via pole masses at one loop, and apply it to both a toy model and to the $$\mu $$ μ NMSSM as prototypes where the standard treatment can break down.

scholarly journals Strong gauging or decoupling ghost matter

2015 ◽  
Vol 30 (24) ◽  
pp. 1550155
Author(s):  
Yu Nakayama
Keyword(s):  
Field Theory ◽  
Fixed Point ◽  
Effective Field Theory ◽  
Gauge Theories ◽  
Central Charge ◽  
Effective Field ◽  
Strongly Coupled ◽  
Weakly Coupled ◽  
Simple Deformation ◽  
Charge Formula

Gauging extra matter is a common way to couple two CFTs discontinuously. We may consider gauging matter by strongly coupled gauge theories at criticality rather than by weakly coupled (asymptotic free) gauge theories. It often triggers relevant deformations and possibly leads to a nontrivial fixed point. In many examples such as the IR limit of SQCDs (and their variants), the relevant RG flow induced by this strong gauging makes the total central charge [Formula: see text] increase rather than decrease compared with the sum of the original decoupled CFTs. The dilaton effective field theory argument given by Komargodski and Schwimmer does not apply because strong gauging is not a simple deformation by operators in the original two decoupled CFTs and it may not be UV complete. When the added matter is vector-like, one may emulate strong gauging in a UV completed manner by decoupling of ghost matter. While the UV completed description makes the dilaton effective field theory argument possible, due to the nonunitarity, we cannot conclude the positivity of the central charge difference in accordance with the observations in various examples that show the contrary.

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