Radiative pion decay in a simple quark loop model

1976 ◽  
Vol 54 (2) ◽  
pp. 158-163 ◽  
Author(s):  
L. Resnick ◽  
J. H. Kim
Keyword(s):  
Basic Assumption ◽  
Dimensional Regularization ◽  
Weak Decay ◽  
Coupling Constants ◽  
Pion Decay ◽  
Loop Model ◽  
Quark Loop ◽  
Quark Masses ◽  
The One ◽  
The Masses

The weak decay of pions into leptons and into leptons plus photon is examined in a simple model at the one loop level. A basic assumption made is that there is more than one pair of quarks to which the pion couples and the masses and coupling constants are such that all amplitudes are finite. The amplitudes are defined by means of dimensional regularization and gauge invariance is rigorously maintained throughout. The experimental lifetimes for charged and neutral pion decay give one constraint among the quark masses and the parameter γ, the ratio of structure dependent axial to vector form factor, gives a second. Quark masses can be found to satisfy either condition, but no solution exists for both constraints simultaneously.

Pion structure in a modified quark loop model

1980 ◽  
Vol 58 (7) ◽  
pp. 964-968 ◽  
Author(s):  
J. H. Kim ◽  
L. Resnick
Keyword(s):  
Form Factor ◽  
Bound State ◽  
Weak Decay ◽  
Loop Model ◽  
Vector Structure ◽  
Pion Structure ◽  
The One ◽  
System Coupling ◽  
State Nature ◽  
Good Agreement

The pion is assumed as usual to couple to the electroweak currents through its constituent quarks. The bound state nature of the [Formula: see text] system coupling to the electroweak currents is simulated by a form factor at the [Formula: see text] vertex, parametrized by an effective mass M and coupling strength f. Calculations are performed at the one loop level, with a prescription used to ensure electromagnetic gauge invariance. Isospin invariance is assumed. f, M, and the effective quark mass m are determined by the normalization condition for the pion electromagnetic form factor and the charged and neutral pion lifetimes. The charge radius of the pion is calculated and found to be in good agreement with experiment. The ratio of the axial to vector structure functions in the radiative weak decay π → evγ is also determined.

scholarly journals COMPLETE CLASSES OF GUTS WITH VANISHING ONE-LOOP BETA FUNCTIONS

1994 ◽  
Vol 09 (29) ◽  
pp. 5053-5075
Author(s):  
WOLFGANG LUCHA ◽  
FRANZ F. SCHÖBERL
Keyword(s):  
Gauge Coupling ◽  
Coupling Constants ◽  
Coupling Constant ◽  
Finiteness Conditions ◽  
Grand Unified Theories ◽  
Unified Theories ◽  
Dimensionless Coupling ◽  
The One ◽  
The Masses ◽  
Gauge Coupling Constant

By explicit solution of the one-loop finiteness conditions for all dimensionless coupling constants (i.e. the gauge coupling constant as well as Yukawa and quartic scalar-boson self-interaction coupling constants), two classes of grand unified theories characterized by renormalization-group beta functions which all vanish at least at the one-loop level are constructed and analyzed with respect to the (suspected) appearance of quadratic divergences, with the result that without exception in all of these models the masses of both vector and scalar bosons receive quadratically divergent one-loop contributions.

scholarly journals Quantum aspects of Yukawa model with scalar and axial scalar fields in curved spacetime

2019 ◽  
Vol 79 (12) ◽  
Author(s):  
Iosif L. Buchbinder ◽  
Andreza Rairis Rodrigues ◽  
Eduardo Antonio dos Reis ◽  
Ilya L. Shapiro
Keyword(s):  
Effective Potential ◽  
Dimensional Regularization ◽  
Scalar Fields ◽  
Coupling Constants ◽  
Dirac Fermions ◽  
Yukawa Model ◽  
Curved Spacetime ◽  
Renormalization Group Approach ◽  
The One ◽  
Local Momentum

AbstractWe study the Yukawa model with one scalar and one axial scalar fields, coupled to N copies of Dirac fermions, in curved spacetime background. The theory possesses a reach set of coupling constants, including the scalar terms with odd powers of scalar fields in the potential, and constants of non-minimal coupling of the scalar fields to gravity. Using the heat-kernel technique and dimensional regularization, we derive the one-loop divergences, describe the renormalization of the theory under consideration and calculate the full set of beta- and gamma-functions for all coupling constants and fields. As a next step, we construct the renormalized one-loop effective potential of the scalar fields up to the terms linear in scalar curvature. This calculation includes only the contributions from quantum scalar fields, and is performed using covariant cut-off regularization and local momentum representation. Some difficulties of the renormalization group approach to the effective potential in the case under consideration are discussed.

Social Capital and the Development of Political Support in Europe

2017 ◽  
Author(s):  
Marc Hooghe ◽  
Anna Kern
Keyword(s):  
Social Capital ◽  
Basic Assumption ◽  
Voluntary Associations ◽  
Political Trust ◽  
European Social Survey ◽  
Political Support ◽  
Civil Society Organizations ◽  
Social Survey ◽  
The One ◽  
Democratic Norms

This chapter evaluates the claim that the decline of legitimacy is due to a decline of social capital. The idea that voluntary associations play an important role in establishing social cohesion and political support is a traditional insight in the field of political sociology. The basic assumption is that voluntary associations function as a training ground for democracy, where citizens involved acquire democratic norms and skills that they subsequently apply in their relation with the political system. If this argument is correct, political support should be at least partly influenced by citizens’ participation in civil society organizations. Using European Social Survey data from 2006 and 2012 the authors demonstrate that there is a clear and significant correlation between social involvement on the one hand and satisfaction with the working of democracy and political trust on the other, which largely survives the introduction of a range of control variables.

scholarly journals Challenges for a QCD axion at the 10 MeV scale

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Jia Liu ◽  
Navin McGinnis ◽  
Carlos E. M. Wagner ◽  
Xiao-Ping Wang
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Multiple Sources ◽  
Standard Model Extension ◽  
Mixing Angles ◽  
Quark Masses ◽  
Model Extension ◽  
The One

Abstract We report on an interesting realization of the QCD axion, with mass in the range $$ \mathcal{O} $$ O (10) MeV. It has previously been shown that although this scenario is stringently constrained from multiple sources, the model remains viable for a range of parameters that leads to an explanation of the Atomki experiment anomaly. In this article we study in more detail the additional constraints proceeding from recent low energy experiments and study the compatibility of the allowed parameter space with the one leading to consistency of the most recent measurements of the electron anomalous magnetic moment and the fine structure constant. We further provide an ultraviolet completion of this axion variant and show the conditions under which it may lead to the observed quark masses and CKM mixing angles, and remain consistent with experimental constraints on the extended scalar sector appearing in this Standard Model extension. In particular, the decay of the Standard Model-like Higgs boson into two light axions may be relevant and leads to a novel Higgs boson signature that may be searched for at the LHC in the near future.

MULTIVERSE COSMOLOGICAL MODELS

2004 ◽  
Vol 19 (10) ◽  
pp. 727-743 ◽  
Author(s):  
P. C. W. DAVIES
Keyword(s):  
String Theory ◽  
Selection Effect ◽  
Elementary Particles ◽  
Cosmological Models ◽  
Anthropic Principle ◽  
Coupling Constants ◽  
Inflationary Cosmology ◽  
Physical Parameters ◽  
Recent Advances ◽  
The Masses

Recent advances in string theory and inflationary cosmology have led to a surge of interest in the possible existence of an ensemble of cosmic regions, or "universes", among the members of which key physical parameters, such as the masses of elementary particles and the coupling constants, might assume different values. The observed values in our cosmic region are then attributed to an observer selection effect (the so-called anthropic principle). The assemblage of universes has been dubbed "the multiverse". In this paper we review the multiverse concept and the criticisms that have been advanced against it on both scientific and philosophical grounds.

scholarly journals ONE-LOOP EFFECTIVE POTENTIAL FOR SCALAR AND VECTOR FIELDS ON HIGHER-DIMENSIONAL NONCOMMUTATIVE FLAT MANIFOLDS

2001 ◽  
Vol 16 (23) ◽  
pp. 1479-1486 ◽  
Author(s):  
A. A. BYTSENKO ◽  
A. E. GONÇALVES ◽  
S. ZERBINI
Keyword(s):  
Zeta Function ◽  
Vector Fields ◽  
Dimensional Regularization ◽  
Massless Scalar ◽  
Quantum Field Theories ◽  
Dimensional Manifold ◽  
Logarithmic Term ◽  
Scalar And Vector Fields ◽  
The One ◽  
Flat Manifolds

The non-planar contribution to the effective potentials for massless scalar and vector quantum field theories on D-dimensional manifold with p compact noncommutative extra dimensions is evaluated by means of dimensional regularization implemented by zeta function techniques. It is found that, the zeta function associated with the one-loop operator may not be regular at the origin. Thus, the related heat kernel trace has a logarithmic term in the short t asymptotic expansion. Consequences of this fact are briefly discussed.

scholarly journals Symmetry breakdown and coupling constants of leptons

2007 ◽  
Vol 79 (2) ◽  
pp. 195-208 ◽  
Author(s):  
Gil C. Marques ◽  
Dominique Spehler
Keyword(s):  
Coupling Constants ◽  
Electroweak Interactions ◽  
New Approach ◽  
Fundamental Interactions ◽  
Electromagnetic Interactions ◽  
Symmetry Breakdown ◽  
A Value ◽  
Intermediate Bosons ◽  
The One ◽  
The Way

Based on a new approach to symmetries of the fundamental interactions we deal, in this paper, with the electroweak interactions of leptons. We show that the coupling constants, arising in the way leptons are coupled to intermediate bosons, can be understood as parameters associated to the breakdown of SU(2) and parity symmetries. The breakdown of both symmetries is characterized by a new parameter (the asymetry parameter) of the electroweak interactions. This parameter gives a measure of the strength of breakdown of symmetries. We analyse the behaviour of the theory for three values of this parameter. The most relevant value is the one for which only the electromagnetic interactions do not break parity (the maximally allowed left-right asymetric theory). Maximamally allowed parity asymmetry is a requirement that is met for a value of Weinberg's theta-angle that is quite close to the experimental value of this parameter.

scholarly journals The Cultural Populism of Iosif I. Kablits (Yuzov) and its Foundations

2020 ◽  
Vol 19 (3) ◽  
pp. 641-653
Author(s):  
Gennadiy N. Mokshin
Keyword(s):  
Social Life ◽  
Cultural Work ◽  
Right Wing ◽  
Social Transformations ◽  
Leading Role ◽  
The People ◽  
Long Time ◽  
The One ◽  
The Right ◽  
The Masses

This article reconstructs the cultural doctrine of the famous publicist of populism (narodnichestvo), I.I. Kablits (Yuzov). To just equate Kablits views with the slogan of yuzovshchina would be a narrow interpretation of his kul'turnichestvo; the slogan is characteristic for extreme right-wing populism during the upsurge of the revolutionary populist movement (narodovol'cheskoe dvizhenie). In 1880, Kablits was the first of the legal populists to pose the question, What is populism? According to the publicist, true narodnichestvo should be based on the principle that the forms of public life of the people must be in conformity with the development level of their consciousness. The author explains Kablits evolution from Bakunism to a peasant-centered narodnichestvo by his interpretation of the reasons for the split between the intelligentsia and the people. Kablits considered them antagonists, and defined the ultimate goal of the narodniki as the liberation of the people from the power of the intellectualbureaucratic minority, the latter supposedly trying to subjugate the life of the masses to its will. The article analyzes the main provisions of Kablits sociocultural concept of social transformations: apolitism, populism, and the initiative of the masses. The article identifies the differences between his program of developing the cultural identity of the people, on the one hand, and other populists' understanding of the tasks of cultural work, on the other. Particular attention is paid to Kablits-Yuzov's attitude towards the problem of educating the masses. Kablits was one of the few Russian populists who opposed the idea that the foundations of the worldview of the people must be changed, arguing that this would eliminate the traditional moral values of the village, including the sense of collectivism. The author assesses how Kablits, the leading publicist of the newspaper Nedelya, contributed to the establishment of a cultural direction in narodnichestvo at the turn of the 1870s and 1880s. According to the author, Kablits played a leading role in shaping the ideology of the right flank of the cultural direction in narodnichestvo. However, the pure populism of Kablits turned out to be too pseudo-scientific, dogmatic and irrational to attract the democratic intelligentsia for a long time; the latter had already become disillusioned with the idea of the people as the creator of new forms of social life.

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