分类： 物理学 >> 凝聚态:结构、力学和热性能 提交时间： 2017-03-26
摘要：The recent multiple solutions problem in high energy physics has been reviewed with a more mathematical viewpoint. Although previously these multiple solutions are found via fit process, in this letter we have proved that if a sum of two coherent simple Breit-Wigner functions is used to fit the measured distribution, there should be two and only two non-trivial solutions, which are related with each other by analytical formulae.
分类： 物理学 >> 凝聚态:结构、力学和热性能 提交时间： 2017-03-26
摘要：The resonance parameters of the excited ψ-family resonances, namely the ψ(4040), ψ(4160), and ψ(4415), were determined by fitting the R-values measured by experiments. It is found that the previously reported leptonic partial widths of these states were merely one possible solutions among a four-fold ambiguity. By fitting the most precise experimental data on the R-values measured by the BES collaboration, this work presents all four sets of solutions. These results may affect the interpretation of the charmonium and charmonium-like states above 4 GeV/c2.
分类： 物理学 >> 凝聚态:结构、力学和热性能 提交时间： 2017-03-26
摘要：Multiple solutions exist in many experimental situations when several interfering amplitudes are summed to fit experimentally measured distributions, such as cross sections, mass spectra, and/or the angular distributions. We show a few examples where multiple solutions are found, but only one solution is reported in the publications. Since there is no standard rule for choosing one among the solutions as the physics one, we propose a simple rule that agrees with what has been adopted in previous literatures: the solution corresponding to the minimal magnitudes of the amplitudes must be the physical solution. We suggest test this rule in the future analyses.
分类： 物理学 >> 凝聚态:结构、力学和热性能 提交时间： 2017-03-26
摘要：By fitting the R values between 3.7 and 5.0 GeV measured by the BES Collaboration, the upper limit of the electron width of the newly discovered resonance Y(4260) is determined to be 240 eV at 90% C.L. Together with the BaBar measurement on Γee• B(Y(4260) → π+π- J/ψ), this implies a large decay width of Y (4260) → π+π- J/ψ final states.
分类： 物理学 >> 凝聚态:结构、力学和热性能 提交时间： 2017-03-26
摘要：The previous experiments which provide information on the ψ(3770) to non-DD decays are reviewed. Three approaches of searching for the non-D(D) decays are discussed in detail. It is also pointed out that the search for the non-D(D) decays of the ψ(3770) is very important for the understanding of the dynamics of charmonium decays.
分类： 物理学 >> 凝聚态:结构、力学和热性能 提交时间： 2017-03-26
摘要：It is suggested that the newly observed Y(4260) by BaBar Collaboration is a molecular state composed of an ω and a χc1. Both the production and decay properties are discussed. A consequence for this molecular state, Y(4260), is that it decays copiously into π+π-π0χcl. It is also expected that Y(4260) →π0π0J/ψ is produced at half rate as Y(4260) →π0π0J/ψ. These decay modes should be searched for in the B factories using initial state radiative return data and B decay data as well.
分类： 物理学 >> 凝聚态:结构、力学和热性能 提交时间： 2017-03-26
摘要：The baryon–antibaryon SU(3) nonets are proposed as a scheme to classify the increased number of experimentally observed enhancements near the baryon antibaryon mass threshold. The scheme is similar to the Fermi–Yang–Sakata model, which was put forth about fifty years ago in explaining the mesons observed at that time. According to the present scheme, many new baryon–antibaryon bound states are predicted, and their possible productions in quarkonium decays and B decays are suggested for experimental search.
分类： 物理学 >> 凝聚态:结构、力学和热性能 提交时间： 2017-03-26
摘要：The branching fraction of the ψ" decays into charmless final states is estimated in the S- and D-wave charmonia mixing scheme. With the information of the hadronic decays of J/ψ and ψ', it is found that a large branching fraction, up to 13% of the total ψ" decays, may go to charmless final states. The experimental search for these decays is also discussed.
分类： 物理学 >> 凝聚态:结构、力学和热性能 提交时间： 2017-03-26
摘要：Adding to the long standing “ρπ puzzle” in ψ′and J/ψ decays, recently BEijing Spectrometer (BES) reported B(ψ′→ K0SK0L) which is enhanced relative to the pQCD “12% rule” expectation from B(J/ψ → K0SK0L). If the enhancement is due to the mixing of the S- and D-wave charmonium states as in the ρπ case, the newly measured B(ψ′ → K0SK0L) gives a constraint on B(ψ″ → K0SK0L).It erves as a good test for the scenario of the S- and D-wave mixing in the ψ′and ψ″.
分类： 物理学 >> 凝聚态:结构、力学和热性能 提交时间： 2017-03-26
摘要：The measurements of ψ (2 S )→ ωπ 0 and ψ (2 S )→ π + π − in e + e − experiments are examined. It is found that the non-resonance virtual photon annihilation gives large contributions to the observed cross sections of these two processes. By including this contribution, the form factors and branching fractions of these two decay modes are revised.
分类： 物理学 >> 核物理学 提交时间： 2016-09-18
摘要：Proton spin is investigated in chiral effective field theory through an examination of the singlet axial charge, a0, and the two non-singlet axial charges, a3 and a8. Finite-range regularization is considered as it provides an effective model for estimating the role of disconnected sea-quark loop contributions to baryon observables. Baryon octet and decuplet intermediate states are included to enrich the spin and flavour structure of the nucleon, redistributing spin under the constraints of chiral symmetry. In this context, the proton spin puzzle is well understood with the calculation describing all three of the axial charges reasonably well. The strange quark contribution to the proton spin is negative with magnitude 0.01. With appropriate Q2 evolution, we find the singlet axial charge at the experimental scale to be a^0=0.31+0.04−0.05, consistent with the range of current experimental values.
分类： 物理学 >> 核物理学 提交时间： 2016-09-13
摘要：We propose the pure sea-quark contributions to the magnetic form factors of Σ baryons, GuΣ− and GdΣ+, as priority observables for the examination of sea-quark contributions to baryon structure, both in present lattice QCD simulations and possible future experimental measurement. GuΣ−, the u-quark contribution to the magnetic form factor of Σ−, and GdΣ+, the d-quark contribution to the magnetic form factor of Σ+, are similar to the strange quark contribution to the magnetic form factor of the nucleon, but promise to be larger by an order of magnitude. We explore the size of this quantity within chiral effective field theory, including both octet and decuplet intermediate states. The finite range regularization approach is applied to deal with ultraviolet divergences. Drawing on an established connection between quenched and full QCD, this approach makes it possible to predict the sea quark contribution to the magnetic form factor purely from the meson loop. In the familiar convention where the quark charge is set to unity GuΣ−=GdΣ+. We find a value of −0.38+0.16−0.17 μN, which is about seven times larger than the strange magnetic moment of the nucleon found in the same approach. Including quark charge factors, the u-quark contribution to the Σ− magnetic moment exceeds the strange quark contribution to the nucleon magnetic moment by a factor of 14.
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