Search results for "Particle physics"

Muon capture in11B

1971

In this paper the partial-capture rates of muons in11B going to11Be(g.s.) and11Be (320 keV), as well as the hyperfine effect in the transition to11Be*, are studied. Comparing these results with the beta-decay of11Be and the electromagnetic transition11Be* →11Be, we can derive some conclusions on the nuclear structure of the bound states of11Be. We also discuss some possible experiences which can give information on the pseudoscalar form factor in weak interactions.

Determination of the Pseudoscalar Decay Constant fDs+ via Ds+→μ+νμ

2020

NonleptonicKdecay rate in terms of spectral-function integrals: A short-distance approach

1977

In unified gauge theories of the weak and electromagnetic interactions it is shown that the matrix element for the decay ${K}_{S}^{0}\ensuremath{\rightarrow}2\ensuremath{\pi}$ can reliably be expressed in terms of integrals over spectral functions if (i) modified spectral-function sum rules of the Das, Mathur, and Okubo type are valid, or if (ii) the strong interactions are asymptotically free and the Glashow-Iliopoulos-Maiani mechanism holds. In these cases the contributions of the low-lying pseudoscalar and vector mesons to the spectral-function integrals suffice to account for the decay rate.

Measurement of the π0, η, η′ Transition Form Factors at BABAR

2013

Abstract Measurements of the transition form factors of the pseudoscalar mesons π 0 , η, η ′ have been carried out by the BABAR collaboration at the SLAC B-factory PEP-II. The form factors F ( Q 2 ) were measured in two-photon processes covering the kinematic range 4 GeV 2 Q 2 40 GeV 2 . For the π 0 form factor, results are significantly higher than predicted by Brodsky and Lepage assuming an asymptotic distribution amplitude. Data also suggest that the asymptotic regime of QCD is reached only at relatively high Q 2 . We also report on measurements of the η and η ′ transition form factors, which happen to feature a significantly different Q 2 behaviour than the one of the neutral pion.

Plasmon mass scale and quantum fluctuations of classical fields on a real time lattice

2018

Classical real-time lattice simulations play an important role in understanding non-equilibrium phenomena in gauge theories and are used in particular to model the prethermal evolution of heavy-ion collisions. Above the Debye scale the classical Yang-Mills (CYM) theory can be matched smoothly to kinetic theory. First we study the limits of the quasiparticle picture of the CYM fields by determining the plasmon mass of the system using 3 different methods. Then we argue that one needs a numerical calculation of a system of classical gauge fields and small linearized fluctuations which correspond to quantum fluctuations, in a way that keeps the separation between the two manifest. We demonstra…

The Next Generation of Axion Helioscopes: The International Axion Observatory (IAXO)

2015

Çetin, Serkant Ali (Dogus Author) -- Conference full title: 13th International Conference on Topics in Astroparticle and Underground Physics, TAUP 2013; Asilomar Conference Grounds Monterey Peninsula; United States; 8 September 2013 through 13 September 2013. The International Axion Observatory (IAXO) is a proposed 4th-generation axion helioscope with the primary physics research goal to search for solar axions via their Primakoff conversion into photons of 1 - 10 keV energies in a strong magnetic field. IAXO will achieve a sensitivity to the axion-photon coupling gaγ down to a few ×10-12 GeV-1 for a wide range of axion masses up to ∼ 0.25 eV. This is an improvement over the currently best …

Supersymmetry parameter analysis: SPA convention and project.

2005

18 páginas, 6 figuras, 12 tablas.-- et al.

Low-energy symmetries of QCD and the structure of the nucleon

2015

Abstract We present some updated results regarding the scalar and electromagnetic structure of the nucleon obtained by the relativistic formulation of chiral effective field theory with baryons. We compare them with previous determinations available in the literature, and show their relevance for searches of physics beyond the standard model in the low energy frontier.

ElectromagneticN→N*(1535)transition in the relativistic constituent-quark model

1990

We study a light-cone model of the nucleon and the ${S}_{11}(1535)$ resonance which provides a relativistic generalization of the constituent-quark model in the nonperturbative low-${Q}^{2}$ regime. The two parameters of the model, namely, the size parameter $\ensuremath{\alpha}$ and the constituent-quark mass ${m}_{q}\ensuremath{\approx}300$ MeV, are fixed by the axial form factor. We find good agreement for the electromagnetic form factors of the nucleon up to ${Q}^{2}\ensuremath{\approx}1\ensuremath{-}2$ Ge${\mathrm{V}}^{2}$. All static properties of the nucleon, except for the neutron charge radius, are reproduced within 10%. In addition, we show that the electromagnetic current of the …

Low energy structure of the nucleon from chiral effective field theory

2014

We present some updated results regarding the scalar and electromagnetic structure of the nucleon obtained by the relativistic formulation of chiral effective field theory with baryons. We compare them with previous determinations available in the literature, and show their relevance for searches of physics beyond the standard model in the low energy frontier. An accurate knowledge of the structure of the nucleon is important to improve our understanding of the funda- mental interactions and provide theoretical estimations of some important quantities with a small uncertainty. This is specially relevant for experiential searches of physics be- yond the standard model in the low energy front…