scholarly journals AN ANALYTIC METHOD OF DESCRIBING R-RELATED QUANTITIES IN QCD

2006 ◽  
Vol 21 (17) ◽  
pp. 1355-1368 ◽  
Author(s):  
K. A. MILTON ◽  
I. L. SOLOVTSOV ◽  
O. P. SOLOVTSOVA
Keyword(s):  
Light Quark ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Analytic Method ◽  
Suggested Model ◽  
Quark Masses ◽  
Vector Channel ◽  
Hadronic Contribution ◽  
Decay Widths ◽  
Physical Quantities

A model based on the analytic approach to QCD, involving a summation of threshold singularities and taking into account the nonperturbative character of the light quark masses, is applied to find hadronic contributions to different physical quantities. It is shown that the suggested model allows us to describe well such objects as the hadronic contribution to the anomalous magnetic moment of the muon, the ratio of hadronic to leptonic τ-decay widths in the vector channel, the Adler D-function, the smeared RΔ-function, and the hadronic contribution to the evolution of the fine structure constant.

scholarly journals Leading isospin-breaking corrections to meson masses on the lattice

2018 ◽  
Vol 175 ◽  
pp. 06002 ◽  
Author(s):  
Davide Giusti ◽  
Vittorio Lubicz ◽  
Guido Martinelli ◽  
Francesco Sanfilippo ◽  
Silvano Simula ◽  
...  
Keyword(s):  
Fine Structure ◽  
Quark Mass ◽  
Light Quark ◽  
Structure Constant ◽  
Mass Splitting ◽  
Fine Structure Constant ◽  
Isospin Breaking ◽  
Decay Constants ◽  
Quark Masses ◽  
Small Parameters

We present a study of the isospin-breaking (IB) corrections to pseudoscalar (PS) meson masses using the gauge configurations produced by the ETM Collaboration with Nf = 2+1+1 dynamical quarks at three lattice spacings varying from 0.089 to 0.062 fm. Our method is based on a combined expansion of the path integral in powers of the small parameters [see formula in PDF] and αem, where [see formula in PDF] is the renormalized quark mass and αem the renormalized fine structure constant. We obtain results for the pion, kaon and Dmeson mass splitting; for the Dashen’s theorem violation parameters ϵγ(MM, 2 GeV), ϵπ0 ϵK0(MS, 2 GeV) for the light quark masses [see formula in PDF] for the flavour symmetry breaking parameters R(MS, 2 GeV) and Q(MS, 2 GeV) and for the strong IB effects on the kaon decay constants.

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.

scholarly journals Measurement of the running of the fine structure constant below 1 GeV with the KLOE detector

2019 ◽  
Vol 218 ◽  
pp. 02012
Author(s):  
Graziano Venanzoni
Keyword(s):  
Fine Structure ◽  
Energy Region ◽  
Direct Evidence ◽  
Branching Ratio ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Recent Measurement ◽  
Single Measurement ◽  
Lepton Universality ◽  
Hadronic Contribution

I will report on the recent measurement of the fine structure constant below 1 GeV with the KLOE detector. It represents the first measurement of the running of α(s) in this energy region. Our results show a more than 5σ significance of the hadronic contribution to the running of α(s), which is the strongest direct evidence both in time-and space-like regions achieved in a single measurement. From a fit of the real part of Δα(s) and assuming the lepton universality the branching ratio BR(ω → µ+µ−) = (6.6 ± 1.4stat ± 1.7syst) · 10−5 has been determined

scholarly journals Implications and Applications of Fermi Scale Quantum Gravity

2019 ◽  
Author(s):  
U.V.S. Seshavatharam ◽  
S. Lakshminarayana
Keyword(s):  
Binding Energy ◽  
Structure Constant ◽  
Physical Constant ◽  
Fine Structure Constant ◽  
Electron Mass ◽  
New Approach ◽  
Quark Masses ◽  
Proton Mass ◽  
Nuclear Stability ◽  
Elementary Charge

To understand the mystery of final unification, in our earlier publications, we proposed two bold concepts: 1) There exist three atomic gravitational constants associated with electroweak, strong and electromagnetic interactions. 2) There exists a strong elementary charge in such a way that its squared ratio with normal elementary charge is close to reciprocal of the strong coupling constant. In this paper we propose that, can be considered as a compound physical constant associated with proton mass, electron mass and the three atomic gravitational constants. With these ideas, an attempt is made to understand nuclear stability and binding energy. In this new approach, nuclear binding energy can be fitted with four simple terms having one unique energy coefficient with a formula, where is an estimated mean stable mass number. With this new approach, Newtonian gravitational constant can be estimated in a verifiable approach with a model relation of the form, where is the Fine structure constant. Estimated and is 62 ppm higher than the CODATA recommended It needs further investigation. Proceeding further, an attempt is made to fit the recommended quark masses.

From the standard model to grand unification

1982 ◽  
Vol 304 (1482) ◽  
pp. 69-86 ◽  
Keyword(s):  
Structure Constant ◽  
Fine Structure Constant ◽  
Grand Unification ◽  
Quark Masses ◽  
Grand Unified Theories ◽  
The Standard Model ◽  
Unified Theories ◽  
Order Of Magnitude ◽  
Near Future ◽  
The Universe

This paper reviews the limitations o f the standard SU (3) x SU (2) x U (l) model and develops the philosophy of grand unification. Some simple grand unified theories are presented, and calculations made of the order of magnitude of the fine-structure constant a, as well as of sin 2 0 W and some quark masses. Predictions for nucleon decay and neutrino masses are then discussed; they may be observable in the near future. It is suggested that grand unified theories complex enough for the understanding of the baryon asymmetry of the Universe may also predict a neutron electric dipole moment large enough to be measured. Finally, some inadequacies of GUTs are mentioned.

How Constant are Fundamental Physical Quantities?

1977 ◽  
Vol 32 (6) ◽  
pp. 532-537 ◽  
Author(s):  
W. Eichendorf ◽  
M. Reinhardt
Keyword(s):  
Gravitational Constant ◽  
Structure Constant ◽  
Elementary Particles ◽  
Fine Structure Constant ◽  
Geochemical Data ◽  
Physical Constants ◽  
Elementary Charge ◽  
Physical Quantities ◽  
Fundamental Physical ◽  
Rule Out

Abstract We reinvestigate Dirac's large number hypothesis (LNH) which implies the variation of one or more basic physical constants with time. We show that the ratio of the inertial masses of elementary particles and the fine structure constant a do not vary with time in the LNH.Using geochemical data on the surface temperature of the earth in the precambrian we can rule out Dirac's conjecture that the gravitational constant G is inversely proportional to cosmic epoch with and without matter creation. Our limit on Ġ/G is one of the best available. We can exclude Gamow's proposal to save the LNH by a variation of the elementary charge e. We also put an upper limit on the variation of the mass of elementary particles.With the data available at present, we cannot rule out Dirac's LNH if either the mass of elementary particles or the velocity of light and Planck's constant are time dependent. A few other models of variable physical constants are also discussed and excluded.

Quark mass determinations in QCD

2014 ◽  
Vol 29 (28) ◽  
pp. 1430031 ◽  
Author(s):  
C. A. Dominguez
Keyword(s):  
Heavy Quark ◽  
Light Quark ◽  
Finite Energy ◽  
Experimental Information ◽  
Bottom Quarks ◽  
Spectral Functions ◽  
Quark Masses ◽  
Quark Sector ◽  
Vector Channel ◽  
Systematic Uncertainties

Recent progress on QCD sum rule determinations of the light and heavy quark masses is reported. In the light quark sector a major breakthrough has been made recently in connection with the historical systematic uncertainties due to a lack of experimental information on the pseudoscalar resonance spectral functions. It is now possible to suppress this contribution to the 1% level by using suitable integration kernels in Finite Energy QCD sum rules. This allows to determine the up-, down-, and strange-quark masses with an unprecedented precision of some 8–10%. In the heavy quark sector, the availability of experimental data in the vector channel, and the use of suitable multipurpose integration kernels allows to increase the accuracy of the charm- and bottom-quarks masses to the 1% level.

scholarly journals Oklo reactors and implications for nuclear science

2014 ◽  
Vol 23 (04) ◽  
pp. 1430007 ◽  
Author(s):  
E. D. Davis ◽  
C. R. Gould ◽  
E. I. Sharapov
Keyword(s):  
Recent Work ◽  
Cross Sections ◽  
Nuclear Physics ◽  
Structure Constant ◽  
Resonance Energy ◽  
Mass Scale ◽  
Fine Structure Constant ◽  
Neutron Resonance ◽  
Quark Masses ◽  
Realistic Geometries

We summarize the nuclear physics interests in the Oklo natural nuclear reactors, focusing particularly on developments over the past two decades. Modeling of the reactors has become increasingly sophisticated, employing Monte Carlo simulations with realistic geometries and materials that can generate both the thermal and epithermal fractions. The water content and the temperatures of the reactors have been uncertain parameters. We discuss recent work pointing to lower temperatures than earlier assumed. Nuclear cross-sections are input to all Oklo modeling and we discuss a parameter, the 175 Lu ground state cross-section for thermal neutron capture leading to the isomer 176 m Lu , that warrants further investigation. Studies of the time dependence of dimensionless fundamental constants have been a driver for much of the recent work on Oklo. We critically review neutron resonance energy shifts and their dependence on the fine structure constant α and the ratio Xq = mq/Λ (where mq is the average of the u and d current quark masses and Λ is the mass scale of quantum chromodynamics (QCD)). We suggest a formula for the combined sensitivity to α and Xq that exhibits the dependence on proton number Z and mass number A, potentially allowing quantum electrodynamic (QED) and QCD effects to be disentangled if a broader range of isotopic abundance data becomes available.

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