Search results for "Formalism"
showing 10 items of 357 documents
Simultaneous description of the e+e−→J/ψππ(KK¯) processes
2020
In this work, we provide a simultaneous and accurate description of the ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ and ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}J/\ensuremath{\psi}$ invariant mass distributions of the recent BESIII data on ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}J/\ensuremath{\psi}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, together with the ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}J/\ensuremath{\psi}{K}^{+}{K}^{\ensuremath{-}}$ cross sections at ${e}^{+}{e}^{\ensuremath{-}}$ center-of-mass energies $q=4.23\text{ }\text{ }\mathrm{GeV}$ and $q=4.26\text{ }\text{ }\mathrm{GeV}$. The rescattering effects between p…
Constraints for nuclear PDFs from the LHCb D-meson data
2019
We quantify the impact of LHCb D-meson measurements at $\sqrt{s}=5 \, {\rm TeV}$ on the EPPS16 and nCTEQ15 nuclear PDFs. In our study, the theoretical description of D-meson production is based on the recently developed SACOT-$m_{\rm T}$ variant of the general-mass variable-flavour-number formalism, and the impact on PDFs is estimated via reweighting methods. We pay special attention on the theoretical uncertainties known to us, and are led to exclude the $p_{\rm T}<3 \, {\rm GeV}$ region from our main analysis. The LHCb data can be accommodated well within EPPS16 and nCTEQ15, and the data provide stringent constraints on the gluons in the shadowing/antishadowing regions. No evidence of …
Molecular interpretation of the XYZ states
2012
We study the vector – vector system including all the possible channels with quantum numbers charm = 0, strangeness = 0 around the energy region of 4000 MeV. New states with hidden charm around 4000MeV have been discovered by the B factories. They are intriguingly close to the D*D¯*${D^*}{ar D^*}$ and Ds*D¯s*$D_s^*ar D_s^*$ thresholds and do not have the properties of the charmonium states.We study the possible formation of D*D¯*${D^*}{ar D^*}$ and Ds*D¯s*$D_s^*ar D_s^*$ bound states in the framework of the Hidden Gauge formalism and discuss some of the models that favor the molecular assumption of some XYZ states: The hidden gauge formalism, Heavy baryon Chiral Perturbation Theory and the …
Model analysis of the world data on the pion transition form factor
2012
We discuss the impact of recent Belle data on our description of the pion transition form factor based on the assumption that a perturbative formalism and a nonperturbative one can be matched in a physically acceptable manner at a certain hadronic scale $Q_{0}$. We discuss the implications of the different parameters of the model in comparing with world data and conclude that within experimental errors our description remains valid. Thus we can assert that the low $Q^2$ nonperturbative description together with an additional $1/Q^2$ term at the matching scale have a strong influence on the $Q^2$ behavior up to very high values of $Q^2$ .
Diabatic description of charmoniumlike mesons
2020
We apply the diabatic formalism, first introduced in molecular physics, to the description of heavy-quark mesons. In this formalism the dynamics is completely described by a diabatic potential matrix whose elements can be derived from unquenched lattice QCD studies of string breaking. For energies far below the lowest open flavor meson-meson threshold, the resulting diabatic approach reduces to the well-known Born-Oppenheimer approximation where heavy-quark meson masses correspond to energy levels in an effective quark-antiquark potential. For energies close below or above that threshold, where the Born-Oppenheimer approximation fails, this approach provides a set of coupled Schr\"{o}dinger…
Photo and electroproduction of mesons
1994
The lecture provides an elementary introduction to photo and electroproduction of pseudoscalar mesons in the resonance region. After discussing the general structure of the elementary production amplitude and its symmetry properties the formalism is applied to some interesting physical problems.
Towards extracting the timelike pion form factor on CLS two-flavour ensembles
2017
35th International Symposium on Lattice Field Theory, Lattice 2017, Granada, Spain, 18 Jun 2017 - 24 Jun 2017; The European physical journal / Web of Conferences 175, 05027 (2018). doi:10.1051/epjconf/201817505027
Supersymmetry does not imply mass degeneracy
2004
Abstract It is commonly believed that unbroken supersymmetry (SUSY) implies that all members of a supermultiplet have the same mass. We demonstrate that this is not true, by exhibiting a simple counterexample. We employ the formalism of homeotic fermions, in a simple model where CPT conjugate fermions have different masses. This model can be supersymmetrized to a hypermultiplet of fields which form a representation of the conventional N=2 SUSY algebra. Nevertheless, CPT conjugate states in this hypermultiplet have different masses. These surprising results do not violate either the CPT theorem or the Haag–Lopuszanski–Sohnius theorem.
Photon Scattering Off Nuclei
2018
The study of nuclear and subnuclear structure by means of photon scattering is outlined. Besides a brief exposition of the formalism a few illustrative examples are discussed.
New Accurate Fit of an Extended Set of Saturation Data for the ν3 Band of SF6: Comparison of Hamiltonians in the Spherical and Cubic Tensor Formalisms
2000
An extended set of 321 frequencies of vibration-rotation lines of the nu(3) band of SF(6) has been measured by saturation spectroscopy using various isotopic species of CO(2). A least-squares fit of these data has been performed using an effective Hamiltonian written either with a spherical tensor or with a cubic tensor formalism. We have derived correspondence formulas between the parameters in the two approaches and checked that both formalisms give the same results up to the seventh order. Corrected parameters are given for the fit with a fifth-order Hamiltonian. An accurate representation of the band is obtained at the tenth order (standard deviation approximately 12 kHz) with a remarka…