STRONG SU(2) BREAKING AND MASS SPLITTINGS IN PSEUDOSCALAR MESONS

1996 ◽  
Vol 11 (29) ◽  
pp. 5245-5259 ◽  
Author(s):  
A. N. MITRA
Keyword(s):  
Mass Difference ◽  
Dynamical Symmetry ◽  
Quark Condensate ◽  
Low Energy ◽  
The Self ◽  
Quark Loop ◽  
Self Energy ◽  
A Value ◽  
Pseudoscalar Mesons ◽  
Vector Exchange

The mass splittings within the SU(2) multiplets of pseudoscalar mesons (π, K, D, B) are used as a laboratory to determine the mass difference between d and u quarks (current), through the simplest (two-point) quark-loop diagrams for the self-energies of the corresponding hadrons, together with the associated quark-condensate diagrams within the loops. The second-order e.m. correction is also calculated with a photon line joining the two opposite quark lines in the self-energy loop. The basic ingredient is a hadron–quark-vertex function generated from a vector-exchange-like (chirally invariant) four-fermion Lagrangian (with current quarks) under dynamical symmetry breaking (DχSB), precalibrated to spectroscopy and other important low-energy amplitudes. The results which are expressed as proportional to the u−d mass difference δc, but are otherwise free from any adjustable parameters, reproduce in a rather accurate way all the SU(2) mass differences (from kaon to bottom) with δc = 4.0 MeV, when all the three self-energy diagrams are included. The pion receives only e.m. contributions with a value 5.24 MeV.

ON THE POSSIBLE EXISTENCE OF A DERIVATIVE COUPLING IN QUANTUM ELECTRODYNAMICS

1959 ◽  
Vol 37 (12) ◽  
pp. 1339-1343
Author(s):  
F. A. Kaempffer
Keyword(s):  
Cross Section ◽  
Quantum Electrodynamics ◽  
Mass Difference ◽  
Large Mass ◽  
The Self ◽  
Nucleon Mass ◽  
Muon Scattering ◽  
Derivative Coupling ◽  
Self Energy ◽  
Classical Analogue

Within the framework of quantum electrodynamics there exists the possibility of a derivative coupling between source and photon field, referred to as eΛ-charge, which has no classical analogue. For calculations the usual graph technique can be used, provided the factor eγμ contributed by each vertex in a conventional graph is replaced by ieΛkμ, where Λ is a length characteristic of the new interaction. Using as cutoff the nucleon mass M one finds for a bare source of electronic mass m the self-energy in second order to be Λm/m ≈ 200, if Λ−1 ≈ 60 M. It is argued that the large mass difference between muon and electron may be due to this effect, assuming muon and electron to differ only in that the muon has eΛ-charge whereas the electron has not. An estimate is made of the muon–muon scattering cross section caused by the presence of eΛ-charge on the muon, and it is found that the existence of this derivative coupling may have escaped observation.

Low energy impurity kink in the normal and anomalous self-energies in Bi-cuprate superconductors

2015 ◽  
Vol 29 (25n26) ◽  
pp. 1542005
Author(s):  
Jin Mo Bok ◽  
Jong Ju Bae ◽  
Seung Hwan Hong ◽  
X. J. Zhou ◽  
Han-Yong Choi
Keyword(s):  
Cuprate Superconductors ◽  
Energy Analysis ◽  
Energy Gap ◽  
Low Energy ◽  
The Self ◽  
Energy Term ◽  
Impurity Effects ◽  
Self Energy ◽  
Superconducting Energy Gap ◽  
Arpes Data

The sharp low energy kink (LEK) in quasiparticle (qp) spectra well below the superconducting energy gap observed in the angle-resolved photo-emission spectroscopy (ARPES) of the Bi-cuprates may be understood in terms of the forward scattering impurities located off the Cu–O planes. The relevance of the idea has been established by comparing the calculated normal self-energy from the off-plane impurity effects and the extracted one from the self-energy analysis of [Formula: see text] (Bi2212) ARPES data in Hong et al. [Phys. Rev. Lett. 113, 057001 (2014)]. In addition to the explanation of the LEK, this is a necessary step to analyze ARPES data, to reveal the spectrum of fluctuations promoting superconductivity. We also present the extracted anomalous self-energy from the self-energy analysis, which is its first experimental determination as far as we are aware of. The extracted anomalous self-energy and its implications are discussed in comparison with the calculated impurity self-energy term.

scholarly journals ON THE NONRELATIVISTIC LIMIT OF THE φ4 THEORY IN 2+1 DIMENSIONS

1996 ◽  
Vol 11 (36) ◽  
pp. 2825-2836 ◽  
Author(s):  
M. GOMES ◽  
J.M.C. MALBOUISSON ◽  
A.J. DA SILVA
Keyword(s):  
Quantum Theory ◽  
Scalar Field ◽  
Scattering Amplitude ◽  
Nonrelativistic Limit ◽  
Low Energy ◽  
The Self ◽  
Energy Correction ◽  
Real Scalar ◽  
Self Energy

We study the nonrelativistic limit of the quantum theory of a real scalar field with quartic self-interaction. The two-body scattering amplitude is written in such way as to separate the contributions of high and low energy intermediary states. From this result and the two-loop computation of the self-energy correction, we determine an effective nonrelativistic action.

scholarly journals BARYON SELF-ENERGY WITH qqq BETHE–SALPETER DYNAMICS IN THE NONPERTURBATIVE QCD REGIME: n-p MASS DIFFERENCE

1999 ◽  
Vol 14 (29) ◽  
pp. 4589-4619 ◽  
Author(s):  
ANJU SHARMA ◽  
A. N. MITRA
Keyword(s):  
Vertex Function ◽  
Mass Difference ◽  
Test Case ◽  
Quark Loop ◽  
Dynamical Mass ◽  
Gluon Exchange ◽  
Self Energy ◽  
Nonperturbative Qcd ◽  
Two Parameters ◽  
Three Body

A qqq BSE formalism based on DBχS of an input four-fermion Lagrangian of "current" u, d quarks interacting pairwise via gluon-exchange-propagator in its nonperturbative regime, is employed for the calculation of baryon self-energy via quark-loop integrals. To that end the baryon-qqq vertex function is derived under Covariant Instantaneity Ansatz (CIA), using Green function techniques. This is a three-body extension of an earlier [Formula: see text] (two-body) result on the exact 3D–4D interconnection for the respective BS wave functions under 3D kernel support. The nonperturbative QCD feature of this approach (vis-a-vis chiral perturbation theory — see text for comparison) is preserved through the gluon exchange propagator in the infrared regime (characterized by two parameters C0, ω0), precalibrated to both [Formula: see text] and qqq spectra plus other observables, together with a DBχ S mechanism to generate the dynamical mass m(p). The quark-loop integrals for the neutron (n) – proton (p) mass difference receive contributions from two sources: (i) the strong SU(2) effect arising from the d-u mass difference (4 MeV); (ii) the e.m. effect of the respective quark charges. The resultant n-p difference comes dominantly from the d-u effect (+1.71 MeV ), which is mildly offset by e.m. effect (-0.44), subject to gauge corrections. For an estimate of the latter a general method for QED gauge corrections to an arbitrary momentum dependent vertex function is outlined (in App. C), and a calculation made for the (two-body) kaon as a test case, indicates an increase by 0.612 MeV in the earlier kaon e.m. value (1.032 MeV). This result is taken as a rough indication of the percentage gauge correction expected for the n-p case. A critical comparison is given with the results from QCD sum rules.

Path Integral Calculations of Particle Self-Energy and Effective Mass in Coulomb Systems

1997 ◽  
Vol 11 (04) ◽  
pp. 129-138 ◽  
Author(s):  
V. Sa-Yakanit ◽  
V. D. Lakhno ◽  
Klaus Haß
Keyword(s):  
Effective Mass ◽  
Path Integral ◽  
State Energy ◽  
Coulomb Systems ◽  
Integral Approach ◽  
Coupling Region ◽  
Self Energy ◽  
Consistent Approximation ◽  
A Value ◽  
Wide Range

The generalized path integral approach is applied to calculate the ground state energy and the effective mass of an electron-plasmon interacting system for a wide range of densities. It is shown that in the self-consistent approximation an abrupt transition between the weak coupling and the strong coupling region of interaction exists. The transition occurs at low electron densities according to a value of 418 for rs, when Wigner crystallization is possible. For densities of real metals, the electron bandwidth is calculated and a comparison with experimental results is given.

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 Opacity from Loops in AdS

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Alexandria Costantino ◽  
Sylvain Fichet
Keyword(s):  
Imaginary Part ◽  
Quantum Dynamics ◽  
Model Building ◽  
Asymptotic Properties ◽  
The Self ◽  
Effective Theory ◽  
Self Energy ◽  
Higher Dimensional ◽  
Timelike Region ◽  
Spectral Representations

Abstract We investigate how quantum dynamics affects the propagation of a scalar field in Lorentzian AdS. We work in momentum space, in which the propagator admits two spectral representations (denoted “conformal” and “momentum”) in addition to a closed-form one, and all have a simple split structure. Focusing on scalar bubbles, we compute the imaginary part of the self-energy ImΠ in the three representations, which involves the evaluation of seemingly very different objects. We explicitly prove their equivalence in any dimension, and derive some elementary and asymptotic properties of ImΠ.Using a WKB-like approach in the timelike region, we evaluate the propagator dressed with the imaginary part of the self-energy. We find that the dressing from loops exponentially dampens the propagator when one of the endpoints is in the IR region, rendering this region opaque to propagation. This suppression may have implications for field-theoretical model-building in AdS. We argue that in the effective theory (EFT) paradigm, opacity of the IR region induced by higher dimensional operators censors the region of EFT breakdown. This confirms earlier expectations from the literature. Specializing to AdS5, we determine a universal contribution to opacity from gravity.

scholarly journals Classical gravitational self-energy from double copy

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Gabriel Luz Almeida ◽  
Stefano Foffa ◽  
Riccardo Sturani
Keyword(s):  
Gravitational Field ◽  
Binary System ◽  
The Self ◽  
Gravitational Coupling ◽  
Leading Order ◽  
Body System ◽  
Self Energy ◽  
Composite Systems ◽  
Body Dynamics ◽  
Double Copy

Abstract We apply the classical double copy to the calculation of self-energy of composite systems with multipolar coupling to gravitational field, obtaining next-to-leading order results in the gravitational coupling GN by generalizing color to kinematics replacement rules known in literature. When applied to the multipolar description of the two-body system, the self-energy diagrams studied in this work correspond to tail processes, whose physical interpretation is of radiation being emitted by the non-relativistic source, scattered by the curvature generated by the binary system and then re-absorbed by the same source. These processes contribute to the conservative two-body dynamics and the present work represents a decisive step towards the systematic use of double copy within the multipolar post-Minkowskian expansion.

Sign in / Sign up

Export Citation Format

Share Document