scholarly journals OFF-SHELL EFFECTIVE LAGRANGIAN FOR NRQCD AND HEAVY QUARKS EFFECTIVE THEORY

2001 ◽  
Vol 16 (23) ◽  
pp. 1525-1529
Author(s):  
J. GAMBOA ◽  
S. LEPE ◽  
L. VERGARA
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Relativistic Quantum ◽  
Heavy Quarks ◽  
Effective Field ◽  
Effective Theory ◽  
Tree Level ◽  
Systematic Method ◽  
Method Of Calculation ◽  
Effective Lagrangian

A derivation of the effective Lagrangian for non-relativistic quantum chromodynamics and the heavy quarks effective field theory is given. Our calculation provides a simple and systematic method of calculation of the full off-shell effective Lagrangian at tree level including all the 1/m corrections.

scholarly journals EXCLUSIVE B MESON RARE DECAYS AND GENERAL RELATIONS OF FORM FACTORS IN EFFECTIVE FIELD THEORY OF HEAVY QUARKS

2003 ◽  
Vol 18 (11) ◽  
pp. 1959-1989 ◽  
Author(s):  
M. ZHONG ◽  
Y. L. WU ◽  
W. Y. WANG
Keyword(s):  
Field Theory ◽  
Rare Decays ◽  
Effective Field Theory ◽  
B Meson ◽  
Form Factors ◽  
Heavy Quarks ◽  
Effective Field ◽  
Effective Theory ◽  
Leading Order ◽  
General Relations

B meson rare decays ([Formula: see text] and B → K* γ) are analyzed in the framework of effective field theory of heavy quarks. The semileptonic and penguin type form factors for these decays are calculated by using the light cone sum rules method at the leading order of 1/mQexpansion. Four exact relations between the two types of form factors are obtained at the leading order of 1/mQexpansion. In particular, the relations are found to hold for the whole momentum transfer region. We also investigate the validity of the relations resulting from the large energy effective theory based on the general relations obtained in the present approach. The branching ratios of the rare decays are presented and their potential importance for extracting the CKM matrix elements and probing new physics is emphasized.

scholarly journals HQEFT as a Large Component QCD and Comments on the Incompleteness of HQET

2003 ◽  
Vol 18 (19) ◽  
pp. 1303-1316 ◽  
Author(s):  
Y. L. Wu ◽  
Y. A. Yan ◽  
M. Zhong ◽  
Y. B. Zuo ◽  
W. Y. Wang
Keyword(s):  
Field Theory ◽  
Heavy Quark ◽  
Effective Field Theory ◽  
Heavy Quarks ◽  
Nonrelativistic Limit ◽  
Effective Field ◽  
Effective Theory ◽  
Heavy Quark Effective Theory ◽  
Large Component ◽  
Nonrelativistic Qcd

The heavy quark effective field theory (HQEFT) is revisited in a more intuitive way. It is shown that HQEFT is a consistent large component QCD of heavy quarks. In the nonrelativistic limit, HQEFT recovers the nonrelativistic QCD (NRQCD). The resulting new effects in the HQEFT of QCD are carefully re-examined. It is then natural to give comments on the usual heavy quark effective theory (HQET). Consistent phenomenological applications of HQEFT exhibit its interesting features and completeness in comparison with HQET. It then becomes manifest why we shall base on the HQEFT of QCD rather than HQET which is incomplete for computing 1/mQcorrections. More precise extraction for ∣Vcb∣ and ∣Vub∣ in the HQEFT of QCD is emphasized.

scholarly journals Effective field theory for heavy vector resonances coupled to the Standard Model

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Mathias Heiles ◽  
Matthias König ◽  
Matthias Neubert
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
New Physics ◽  
Effective Field ◽  
Effective Theory ◽  
Effective Lagrangian ◽  
Scale Ratio ◽  
Rigorous Framework ◽  
Physics Model

Abstract We construct an effective field theory describing the decays of a heavy vector resonance V into Standard Model particles. The effective theory is built using an extension of Soft-Collinear Effective Theory called SCETBSM, which provides a rigorous framework for parameterizing decay matrix elements with manifest power counting in the ratio of the electroweak scale and the mass of the resonance, λv/mV. Using the renormalization-group evolution of the couplings in the effective Lagrangian, large logarithms associated with this scale ratio can be resummed to all orders. We consider in detail the two-body decays of a heavy Z′ boson and of a Kaluza-Klein gluon at leading and subleading order in λ. We illustrate the matching onto SCETBSM with a concrete example of a UV-complete new-physics model.

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.

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 EFFECTIVE FIELD THEORY OF IDEAL-FLUID HYDRODYNAMICS

1996 ◽  
Vol 10 (21) ◽  
pp. 999-1010 ◽  
Author(s):  
ADRIAAN M.J. SCHAKEL
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Effective Field ◽  
Effective Theory ◽  
Goldstone Mode ◽  
Hydrodynamic Equations ◽  
Standard Description ◽  
Spontaneous Breakdown ◽  
Sound Mode ◽  
Fluid Hydrodynamics

Starting from a standard description of an ideal, isentropic fluid, we derive the effective theory governing a gapless non-relativistic mode — the sound mode. The theory, which is dictated by the requirement of Galilei invariance, entails the entire set of hydrodynamic equations. The gaplessness of the sound mode is explained by identifying it as the Goldstone mode associated with the spontaneous breakdown of Galilei invariance. Differences with a superfluid are pointed out.

scholarly journals Cosmological phase transitions: is effective field theory just a toy?

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Marieke Postma ◽  
Graham White
Keyword(s):  
Field Theory ◽  
Phase Transition ◽  
Phase Transitions ◽  
Effective Field Theory ◽  
New Physics ◽  
Effective Field ◽  
Tree Level ◽  
Dark Sector ◽  
First Order ◽  
First Order Phase

Abstract To obtain a first order phase transition requires large new physics corrections to the Standard Model (SM) Higgs potential. This implies that the scale of new physics is relatively low, raising the question whether an effective field theory (EFT) description can be used to analyse the phase transition in a (nearly) model-independent way. We show analytically and numerically that first order phase transitions in perturbative extensions of the SM cannot be described by the SM-EFT. The exception are Higgs-singlet extension with tree-level matching; but even in this case the SM-EFT can only capture part of the full parameter space, and if truncated at dim-6 operators, the description is at most qualitative. We also comment on the applicability of EFT techniques to dark sector phase transitions.

scholarly journals EXOTIC QUARKONIUM SPECTROSCOPY: X(3872), Zb(10610), AND Zb(10650) IN NON-RELATIVISTIC EFFECTIVE THEORY

2014 ◽  
Vol 35 ◽  
pp. 1460431
Author(s):  
THOMAS MEHEN
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Bound States ◽  
Effective Field ◽  
Effective Theory ◽  
Recent Developments ◽  
Bottom Mesons

This talk summarizes recent developments in quarkonium spectroscopy. I comment on the relation between the Zb(10610) and Zb(10650) and recently observed Zc(3900) and Zc(4025) states. Then I discuss a number of calculations using non-relativistic effective field theory for the X(3872), Zb(10610), and Zb(10650), under the assumption that these are shallow molecular bound states of charm or bottom mesons.

scholarly journals Uncovering the effective spacetime: Lessons from the effective field theory rationale

2015 ◽  
Vol 24 (12) ◽  
pp. 1544019 ◽  
Author(s):  
Carlos Barceló ◽  
Raúl Carballo-Rubio ◽  
Luis J. Garay
Keyword(s):  
Field Theory ◽  
General Relativity ◽  
Cosmological Constant ◽  
Effective Field Theory ◽  
High Energy ◽  
Effective Field ◽  
Effective Theory ◽  
Particle Spectrum ◽  
Low Energies ◽  
Minimal Modification

The cosmological constant problem can be understood as the failure of the decoupling principle behind effective field theory, so that some quantities in the low-energy theory are extremely sensitive to the high-energy properties. While this reflects the genuine character of the cosmological constant, finding an adequate effective field theory framework which avoids this naturalness problem may represent a step forward to understand nature. Following this intuition, we consider a minimal modification of the structure of general relativity which as an effective theory permits to work consistently at low energies, i.e. below the quantum gravity scale. This effective description preserves the classical phenomenology of general relativity and the particle spectrum of the standard model, at the price of changing our conceptual and mathematical picture of spacetime.

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