scholarly journals NONCOMMUTATIVE N = 2 p - p′ SYSTEM

2002 ◽  
Vol 17 (08) ◽  
pp. 1117-1135
Author(s):  
AALOK MISRA
Keyword(s):  
Field Theory ◽  
Low Energy ◽  
Tree Level ◽  
P System ◽  
Star Products ◽  
Energy Limit ◽  
Point Function ◽  
Tree Level Amplitude ◽  
Complex Dimensions ◽  
Open Sector

We analyze several open and mixed sector tree-level amplitudes in N = 2 p - p′ systems with a constant magnetic B turned on. The three-point function vanishes on-shell. The four-point function, in the Seiberg–Witten (SW) low energy limit,2 is local, indicating the possible topological nature of the theory (in the SW low energy limit) and the possible relation between noncommutativeN = 2 p - p′system in two complex dimensions and in the SW limit, and (non)commutativeN = 2 p′ - p′system in two real dimensions. We discuss three extreme noncommutativity limits (after having taken the Seiberg–Witten low energy limit) of the mixed three-point function, and get two kinds of commutative nonassociative generalized star products. We make some speculative remarks related to reproducing the above four-point tree level amplitude in the open sector, from a field theory.

scholarly journals DEFORMATION OF CFT BEYOND THE FIRST ORDER AND CLOSED STRING FIELD THEORY

1994 ◽  
Vol 03 (01) ◽  
pp. 249-252 ◽  
Author(s):  
GREGORY PELTS
Keyword(s):  
Field Theory ◽  
String Field Theory ◽  
Symmetry Algebra ◽  
Closed String ◽  
Space Time ◽  
Low Energy ◽  
Energy Limit ◽  
First Order ◽  
Self Consistent ◽  
Local Space

A self-consistent string field theory with interaction is formulated. The symmetry algebra of this theory includes, in the low-energy limit, local space-time symmetries, and the Brans-Dicke equation describes a class of low-energy solutions.

scholarly journals Extending low energy effective field theory with a complete set of dimension-7 operators

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Yi Liao ◽  
Xiao-Dong Ma ◽  
Quan-Yu Wang
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Cross Sections ◽  
Effective Field Theory ◽  
Degrees Of Freedom ◽  
Independent Set ◽  
Effective Field ◽  
Low Energy ◽  
Tree Level ◽  
The Standard Model

Abstract We present a complete and independent set of dimension-7 operators in the low energy effective field theory (LEFT) where the dynamical degrees of freedom are the standard model five quarks and all of the neutral and charged leptons. All operators are non-Hermitian and are classified according to their baryon (∆B) and lepton (∆L) numbers violated. Including Hermitian-conjugated operators, there are in total 3168, 750, 588, 712 operators with (∆B, ∆L) = (0, 0), (0, ±2), (±1, ∓1), (±1, ±1) respectively. We perform the tree-level matching with the standard model effective field theory (SMEFT) up to dimension-7 (dim-7) operators in both LEFT and SMEFT. As a phenomenological application we study the effective neutrino-photon interactions due to dim-7 lepton number violating operators that are induced and much enhanced at one loop from dim-6 operators that in turn are matched from dim-7 SMEFT operators. We compare various neutrino-photon scattering cross sections with their counterparts in the standard model and highlight the new features. Finally, we illustrate how these effective interactions could arise from ultraviolet completion.

scholarly journals Sum rules in the standard model effective field theory from helicity amplitudes

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Jiayin Gu ◽  
Lian-Tao Wang
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
Sum Rules ◽  
High Energy ◽  
Effective Field ◽  
Low Energy ◽  
Tree Level ◽  
The Standard Model ◽  
Helicity Amplitudes

Abstract The dispersion relation of an elastic 4-point amplitude in the forward direction leads to a sum rule that connects the low energy amplitude to the high energy observables. We perform a classification of these sum rules based on massless helicity amplitudes. With this classification, we are able to systematically write down the sum rules for the dimension-6 operators of the Standard Model Effective Field Theory (SMEFT), some of which are absent in previous literatures. These sum rules offer distinct insights on the relations between the operator coefficients in the EFT and the properties of the full theory that generates them. Their applicability goes beyond tree level, and in some cases can be used as a practical method of computing the one loop contributions to low energy observables. They also provide an interesting perspective for understanding the custodial symmetries of the SM Higgs and fermion sectors.

scholarly journals TWO-LOOP EULER–HEISENBERG EFFECTIVE ACTIONS FROM CHARGED OPEN STRINGS

2006 ◽  
Vol 21 (03) ◽  
pp. 533-557 ◽  
Author(s):  
LORENZO MAGNEA ◽  
RODOLFO RUSSO ◽  
STEFANO SCIUTO
Keyword(s):  
Field Theory ◽  
Partition Function ◽  
Field Strength ◽  
Gauge Field ◽  
Riemann Surfaces ◽  
Explicit Representation ◽  
Low Energy ◽  
Energy Limit ◽  
Open Strings ◽  
Higher Genus

We present the multiloop partition function of open bosonic string theory in the presence of a constant gauge field strength, and discuss its low-energy limit. The result is written in terms of twisted determinants and differentials on higher-genus Riemann surfaces, for which we provide an explicit representation in the Schottky parametrization. In the field theory limit, we recover from the string formula the two-loop Euler–Heisenberg effective action for adjoint scalars minimally coupled to the background gauge field.

scholarly journals Anomaly matching in the symmetry broken phase: Domain walls, CPT, and the Smith isomorphism

2020 ◽  
Vol 8 (4) ◽  
Author(s):  
Itamar Hason ◽  
Zohar Komargodski ◽  
Ryan Thorngren
Keyword(s):  
Field Theory ◽  
Symmetry Breaking ◽  
Domain Walls ◽  
Careful Analysis ◽  
Low Energy ◽  
Topological Field Theory ◽  
Energy Limit ◽  
Topological Field ◽  
Symmetry Structure ◽  
Goldstone Modes

Symmetries in Quantum Field Theory may have ’t Hooft anomalies. If the symmetry is unbroken in the vacuum, the anomaly implies a nontrivial low-energy limit, such as gapless modes or a topological field theory. If the symmetry is spontaneously broken, for the continuous case, the anomaly implies low-energy theorems about certain couplings of the Goldstone modes. Here we study the case of spontaneously broken discrete symmetries, such as \mathbb{Z}_2ℤ2 and TT. Symmetry breaking leads to domain walls, and the physics of the domain walls is constrained by the anomaly. We investigate how the physics of the domain walls leads to a matching of the original discrete anomaly. We analyze the symmetry structure on the domain wall, which requires a careful analysis of some properties of the unbreakable CPTCPT symmetry. We demonstrate the general results on some examples and we explain in detail the mod 4 periodic structure that arises in the \mathbb{Z}_2ℤ2 and TT case. This gives a physical interpretation for the Smith isomorphism, which we also extend to more general abelian groups. We show that via symmetry breaking and the analysis of the physics on the wall, the computations of certain discrete anomalies are greatly simplified. Using these results we perform new consistency checks on the infrared phases of 2+12+1 dimensional QCD.

scholarly journals Towards Feynman rules for conformal blocks

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Sarah Hoback ◽  
Sarthak Parikh
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Hypergeometric Functions ◽  
Power Series Expansion ◽  
Effective Field ◽  
Conformal Block ◽  
Tree Level ◽  
Conformal Blocks ◽  
Simple Set ◽  
Feynman Rules

Abstract We conjecture a simple set of “Feynman rules” for constructing n-point global conformal blocks in any channel in d spacetime dimensions, for external and exchanged scalar operators for arbitrary n and d. The vertex factors are given in terms of Lauricella hypergeometric functions of one, two or three variables, and the Feynman rules furnish an explicit power-series expansion in powers of cross-ratios. These rules are conjectured based on previously known results in the literature, which include four-, five- and six-point examples as well as the n-point comb channel blocks. We prove these rules for all previously known cases, as well as two new ones: the seven-point block in a new topology, and all even-point blocks in the “OPE channel.” The proof relies on holographic methods, notably the Feynman rules for Mellin amplitudes of tree-level AdS diagrams in a scalar effective field theory, and is easily applicable to any particular choice of a conformal block beyond those considered in this paper.

scholarly journals Loops in AdS: from the spectral representation to position space. Part II

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Dean Carmi
Keyword(s):  
Spectral Representation ◽  
Tree Level ◽  
Point Function ◽  
Position Space ◽  
Gross Neveu Model ◽  
Loop Amplitudes

Abstract We continue the study of AdS loop amplitudes in the spectral representation and in position space. We compute the finite coupling 4-point function in position space for the large-N conformal Gross Neveu model on AdS3. The resummation of loop bubble diagrams gives a result proportional to a tree-level contact diagram. We show that certain families of fermionic Witten diagrams can be easily computed from their companion scalar diagrams. Thus, many of the results and identities of [1] are extended to the case of external fermions. We derive a spectral representation for ladder diagrams in AdS. Finally, we compute various bulk 2-point correlators, extending the results of [1].

scholarly journals More on holographic correlators: twisted and dimensionally reduced structures

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Connor Behan ◽  
Pietro Ferrero ◽  
Xinan Zhou
Keyword(s):  
Field Theory ◽  
Theoretical Data ◽  
Infinite Family ◽  
Tree Level ◽  
Chiral Algebra ◽  
Perfect Agreement ◽  
Four Dimensions ◽  
Independent Field ◽  
Superconformal Theories ◽  
Emergent Structure

Abstract Recently four-point holographic correlators with arbitrary external BPS operators were constructively derived in [1, 2] at tree-level for maximally superconformal theories. In this paper, we capitalize on these theoretical data, and perform a detailed study of their analytic properties. We point out that these maximally supersymmetric holographic correlators exhibit a hidden dimensional reduction structure à la Parisi and Sourlas. This emergent structure allows the correlators to be compactly expressed in terms of only scalar exchange diagrams in a dimensionally reduced spacetime, where formally both the AdS and the sphere factors have four dimensions less. We also demonstrate the superconformal properties of holographic correlators under the chiral algebra and topological twistings. For AdS5× S5 and AdS7× S4, we obtain closed form expressions for the meromorphic twisted correlators from the maximally R-symmetry violating limit of the holographic correlators. The results are compared with independent field theory computations in 4d $$ \mathcal{N} $$ N = 4 SYM and the 6d (2, 0) theory, finding perfect agreement. For AdS4× S7, we focus on an infinite family of near-extremal four-point correlators, and extract various protected OPE coefficients from supergravity. These OPE coefficients provide new holographic predictions to be matched by future supersymmetric localization calculations. In deriving these results, we also develop many technical tools which should have broader applicability beyond studying holographic correlators.

TREE DIAGRAMS IN WITTEN’S SUPERSTRING FIELD THEORY

1989 ◽  
Vol 04 (21) ◽  
pp. 2063-2071
Author(s):  
GEORGE SIOPSIS
Keyword(s):  
Field Theory ◽  
Scattering Amplitudes ◽  
Invariant Theory ◽  
Higher Order ◽  
Contact Term ◽  
Tree Level ◽  
Gauge Invariant

It is shown that the contact term discovered by Wendt is sufficient to ensure finiteness of all tree-level scattering amplitudes in Witten’s field theory of open superstrings. Its inclusion in the action also leads to a gauge-invariant theory. Thus, no additional higher-order counterterms in the action are needed.

scholarly journals TOWARDS THE PROOF OF AGT-W RELATION: TODA 3-POINT FUNCTION AND ${\mathcal W}_{1+\infty}$ ALGEBRA

2013 ◽  
Vol 21 ◽  
pp. 138-139
Author(s):  
SHOTARO SHIBA
Keyword(s):  
Field Theory ◽  
Correlation Function ◽  
Point Function ◽  
Gauge Groups ◽  
Promising Direction ◽  
Quiver Gauge Theory ◽  
Conformal Theory ◽  
Conformal Field ◽  
Point Correlation ◽  
Point Correlation Function

The AGT-W relation is a conjecture of the nontrivial duality between 4-dim quiver gauge theory and 2-dim conformal field theory. We verify a part of this conjecture for all the cases of quiver gauge groups by studying on the property of 3-point correlation function of conformal theory. We also mention the relation to [Formula: see text] algebra as one of the promising direction towards the proof of the remaining part.

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