scholarly journals The Dual QCD @ Work: 2018

2018 ◽  
Vol 192 ◽  
pp. 00048
Author(s):  
Andrzej J. Buras
Keyword(s):  
Lattice Qcd ◽  
New Physics ◽  
Low Energy ◽  
Effective Theory ◽  
Matrix Elements ◽  
General Study ◽  
The Road ◽  
The Past ◽  
Recent Developments ◽  
Energy Approximation

The Dual QCD (DQCD) framework, based on the ideas of ’t Hooft and Witten, and developed by Bill Bardeen, Jean-Marc Gérard and myself in the 1980s is not QCD, a theory of quarks and gluons, but a successful low energy approximation of it when applied to K → ππ decays and K¯0 - K0 mixing. After years of silence, starting with 2014, this framework has been further developed in order to improve the SM prediction for the ratio ε'/ε, the ΔI = 1/2 rule and B^K. Most importantly, this year it has been used for the calculation of all K → ππ hadronic matrix elements of BSM operators which opened the road for the general study of ε'/ε in the context of the SM effective theory (SMEFT). This talk summarizes briefly the past successes of this framework and discusses recent developments which lead to a master formula for ε'/ε valid in any extension of the SM. This formula should facilitate the search for new physics responsible for the ε'/ε anomaly hinted by 2015 results from lattice QCD and DQCD.

scholarly journals The low-energy effective theory of axions and ALPs

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Martin Bauer ◽  
Matthias Neubert ◽  
Sophie Renner ◽  
Marvin Schnubel ◽  
Andrea Thamm
Keyword(s):  
High Energy ◽  
New Physics ◽  
Mass Scale ◽  
Low Energy ◽  
Effective Theory ◽  
Loop Order ◽  
Flavor Changing ◽  
Effective Lagrangian ◽  
Anomalous Dimensions ◽  
Pseudoscalar Mesons

Abstract Axions and axion-like particles (ALPs) are well-motivated low-energy relics of high-energy extensions of the Standard Model, which interact with the known particles through higher-dimensional operators suppressed by the mass scale Λ of the new-physics sector. Starting from the most general dimension-5 interactions, we discuss in detail the evolution of the ALP couplings from the new-physics scale to energies at and below the scale of electroweak symmetry breaking. We derive the relevant anomalous dimensions at two-loop order in gauge couplings and one-loop order in Yukawa interactions, carefully considering the treatment of a redundant operator involving an ALP coupling to the Higgs current. We account for one-loop (and partially two-loop) matching contributions at the weak scale, including in particular flavor-changing effects. The relations between different equivalent forms of the effective Lagrangian are discussed in detail. We also construct the effective chiral Lagrangian for an ALP interacting with photons and light pseudoscalar mesons, pointing out important differences with the corresponding Lagrangian for the QCD axion.

scholarly journals Flavour Anomalies in a U(1) SUSY Extension of the SM

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 191
Author(s):  
Alexander Bednyakov ◽  
Alfiia Mukhaeva
Keyword(s):  
Standard Model ◽  
Parameter Space ◽  
Gauge Boson ◽  
New Physics ◽  
Low Energy ◽  
Effective Theory ◽  
The Standard Model ◽  
Meson Mixing ◽  
Additional Anomaly ◽  
Lepton Flavour

Flavour anomalies have attracted a lot of attention over recent years as they provide unique hints for possible New Physics. Here, we consider a supersymmetric (SUSY) extension of the Standard Model (SM) with an additional anomaly-free gauge U(1) group. The key feature of our model is the particular choice of non-universal charges to the gauge boson Z′, which not only allows a relaxation of the flavour discrepancies but, contrary to previous studies, can reproduce the SM mixing matrices both in the quark and lepton sectors. We pay special attention to the latter and explicitly enumerate all parameters relevant for our calculation in the low-energy effective theory. We find regions in the parameter space that satisfy experimental constraints on meson mixing and LHC Z′ searches and can alleviate the flavour anomalies. In addition, we also discuss the predictions for lepton-flavour violating decays B+→K+μτ and B+→K+eτ.

scholarly journals The charm of 331

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Andrzej J. Buras ◽  
Pietro Colangelo ◽  
Fulvia De Fazio ◽  
Francesco Loparco
Keyword(s):  
Neutral Current ◽  
Branching Ratio ◽  
New Physics ◽  
Necessary Condition ◽  
Matrix Elements ◽  
The Past ◽  
The Standard Model ◽  
Free Parameters ◽  
The Difference ◽  
Cp Asymmetries

Abstract We perform a detailed analysis of flavour changing neutral current processes in the charm sector in the context of 331 models. As pointed out recently, in the case of Z′ contributions in these models there are no new free parameters beyond those already present in the Bd,s and K meson systems analyzed in the past. As a result, definite ranges for new Physics (NP) effects in various charm observables could be obtained. While generally NP effects turn out to be small, in a number of observables they are much larger than the tiny effects predicted within the Standard Model. In particular we find that the branching ratio of the mode D0→ μ+μ−, despite remaining tiny, can be enhanced by 6 orders of magnitude with respect to the SM. We work out correlations between this mode and rare Bd,s and K decays. We also discuss neutral charm meson oscillations and CP violation in the charm system. In particular, we point out that 331 models provide new weak phases that are a necessary condition to have non-vanishing CP asymmetries. In the case of ∆ACP, the difference between the CP asymmetries in D0→ K+K− and D0→ π+π−, we find that agreement with experiment can be obtained provided that two conditions are verified: the phases in the ranges predicted in 331 models and large hadronic matrix elements.

scholarly journals Wavefront manipulation by acoustic metasurfaces: from physics and applications

Nanophotonics ◽  
2018 ◽  
Vol 7 (6) ◽  
pp. 1191-1205 ◽  
Author(s):  
Bin Liang ◽  
Jian-chun Cheng ◽  
Cheng-Wei Qiu
Keyword(s):  
Acoustic Waves ◽  
Review Paper ◽  
Three Dimensional ◽  
New Physics ◽  
Research Field ◽  
Acoustic Metamaterials ◽  
Future Directions ◽  
Practical Applications ◽  
The Past ◽  
Recent Developments

AbstractMolding the wavefront of acoustic waves into the desired shape is of paramount significance in acoustics, which however are usually constrained by the acoustical response of naturally available materials. The emergence of acoustic metamaterials built by assembling artificial subwavelength elements provides distinct response to acoustic waves unattainable in nature. More recently, acoustic metasurfaces, a class of metamaterials with a reduced dimensionality, empower new physics and lead to extended functionalities different from their three-dimensional counterparts, enabling controlling, transmitted or reflected acoustic waves in ways that were not possible before. In this review paper, we present a comprehensive view of this rapidly growing research field by introducing the basic concepts of acoustic metasurfaces and the recent developments that have occurred over the past few years. We review the interesting properties of acoustic metasurfaces and their important functionalities of wavefront manipulation, followed by an outlook for promising future directions and potential practical applications.

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 QUANTUM CHROMODYNAMICS AT COLLIDERS

2006 ◽  
Vol 21 (08n09) ◽  
pp. 1792-1804
Author(s):  
JON M. BUTTERWORTH
Keyword(s):  
Quantum Chromodynamics ◽  
Strong Interaction ◽  
Recent Progress ◽  
New Physics ◽  
Effective Theory ◽  
The Past ◽  
Interaction Studies ◽  
Electroweak Sector ◽  
Second Category

QCD is the accepted (that is, the effective) theory of the strong interaction; studies at colliders are no longer designed to establish this. Such studies can now be divided into two categories. The first involves the identification of observables which can be both measured and predicted at the level of a few percent. Such studies parallel those of the electroweak sector over the past fifteen years, and deviations from expectations would be a sign of new physics. These observables provide a firm "place to stand" from which to extend our understanding. This links to the second category of study, where one deliberately moves to regions in which the usual theoretical tools fail; here new approximations in QCD are developed to increase our portfolio of understood processes, and hence our sensitivity to new physics. Recent progress in both these aspects of QCD at colliders is discussed.

CHIRAL SYMMETRY BREAKING AND FORMULAS OF QUARK CONVERSION FOR LOW-ENERGY HADRONIC MATRIX ELEMENTS

1993 ◽  
Vol 08 (05) ◽  
pp. 853-872 ◽  
Author(s):  
ANDREI N. IVANOV
Keyword(s):  
Chiral Symmetry ◽  
Constituent Quark ◽  
Chiral Symmetry Breaking ◽  
Low Energy ◽  
Collective Excitations ◽  
Spontaneous Breaking ◽  
Matrix Elements ◽  
Energy Approximation ◽  
Meson States ◽  
Current Quark

By using the extended Nambu-Jona-Lasinio model for the low-energy approximation of QCD we derive the formulas, being due to spontaneous breaking of chiral symmetry and bosonization, and allowing to express matrix elements of any operator with current-quark fields in the definition in terms of matrix elements of this operator determined via constituent-quark fields interacting with low-lying meson states appearing as [Formula: see text]-collective excitations, which have the self-interactions too.

scholarly journals Charming ALPs

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Adrian Carmona ◽  
Christiane Scherb ◽  
Pedro Schwaller
Keyword(s):  
Ultra Violet ◽  
New Physics ◽  
Low Energy ◽  
Effective Theory ◽  
Tree Level ◽  
Meson Decay ◽  
Fixed Target ◽  
The Standard Model ◽  
Model Independent ◽  
Key Features

Abstract Axion-like particles (ALPs) are ubiquitous in models of new physics explaining some of the most pressing puzzles of the Standard Model. However, until relatively recently, little attention has been paid to its interplay with flavour. In this work, we study in detail the phenomenology of ALPs that exclusively interact with up-type quarks at the tree-level, which arise in some well-motivated ultra-violet completions such as QCD-like dark sectors or Froggatt-Nielsen type models of flavour. Our study is performed in the low-energy effective theory to highlight the key features of these scenarios in a model independent way. We derive all the existing constraints on these models and demonstrate how upcoming experiments at fixed-target facilities and the LHC can probe regions of the parameter space which are currently not excluded by cosmological and astrophysical bounds. We also emphasize how a future measurement of the currently unavailable meson decay D → π + invisible could complement these upcoming searches.

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