Showing papers in "Chinese Physics C in 2010"
TL;DR: The New Muon (g-2) Collaboration at Fermilab has proposed to measure the anomalous magnetic moment of the muon, aμ, a factor of four better than was done in E821 at the Brookhaven AGS, which obtained aμ = [116592089(63)] × 10−11 ± 0.54 ppm as discussed by the authors.
Abstract: The New Muon (g–2) Collaboration at Fermilab has proposed to measure the anomalous magnetic moment of the muon, aμ, a factor of four better than was done in E821 at the Brookhaven AGS, which obtained aμ = [116592089(63)] × 10−11 ±0.54 ppm. The last digit of aμ is changed from the published value owing to a new value of the ratio of the muon-to-proton magnetic moment that has become available. At present there appears to be a difference between the Standard-Model value and the measured value, at the 3 standard deviation level when electron-positron annihilation data are used to determine the lowest-order hadronic piece of the Standard Model contribution. The improved experiment, along with further advances in the determination of the hadronic contribution, should clarify this difference. Because of its ability to constrain the interpretation of discoveries made at the LHC, the improved measurement will be of significant value, whatever discoveries may come from the LHC.
195 citations
TL;DR: In this article, a large air shower particle detector array of 1 km2 (the LHAASO project) at 4300 m a.s.l. is proposed for finding galactic cosmic ray sources.
Abstract: Gamma ray source detection above 30 TeV is an encouraging approach for finding galactic cosmic ray sources. All sky survey for gamma ray sources using wide field of view detector is essential for population accumulation for various types of sources above 100~GeV. In order to target those goals, a large air shower particle detector array of 1 km2 (the LHAASO project) at 4300 m a.s.l. is proposed. By adding two MagicII-type telescopes in the array as proposed, LHAASO will be enhanced in source morphologic investigation power. The proposed array will be utilized also for energy spectrum measurement for individual cosmic ray species above 30 TeV. By re-configuring the wide field of view telescopes into fluorescence light detector array, the aperture of the detector array can be enlarged to cover an energy region above 100 PeV where the second knee is located. Cosmic ray spectrum and composition will be measured in order to transfer an energy scale to ultra high energy cosmic ray experiments.
184 citations
TL;DR: In this article, the authors presented a precise BABAR measurement on the cross section of the leptonic process e+e− → π+π− (γ) from threshold to an energy of 3 GeV with the initial state radiation (ISR) technique, using 232 fb−1 of data collected with the bABAR detector at e−e− center-of-mass energies near 10.58 GeV.
Abstract: We present a precise BABAR measurement on the cross section of the process e+e− → π+π− (γ) from threshold to an energy of 3 GeV with the initial state radiation (ISR) technique, using 232 fb−1 of data collected with the BABAR detector at e+e− center-of-mass energies near 10.58 GeV. The ISR luminosity is determined from a study of the leptonic process e+e− → μ+μ−γ(γ). The leading-order hadronic contribution to the muon magnetic anomaly calculated using the ππ cross section measured from threshold to 1.8 GeV is (514.1 ± 2.2(stat) ±3.1(syst)) × 10−10.
55 citations
KEK1
TL;DR: In this paper, the anomalous magnetic moment of the positive muon aμ was measured with a novel technique utilizing an ultra-cold muon beam accelerated to 300 MeV/c and a 66 cm-diameter muon storage ring without focusing-electric field.
Abstract: A new measurement of the anomalous magnetic moment of the positive muon aμ is proposed with a novel technique utilizing an ultra-cold muon beam accelerated to 300 MeV/c and a 66 cm-diameter muon storage ring without focusing-electric field. This measurement will be complimentary to the previous measurement that achieved 0.54 ppm accuracy with the magic energy of 3.1 GeV in a 14 m diameter storage ring. The proposed experiment aims to achieve the sensitivity down to 0.1 ppm.
53 citations
TL;DR: In this article, the authors provided an accurate study of the spin-1/2 relativistic particle in a magnetic field in non-commutative space by solving the Dirac equation in NC phase space.
Abstract: This work provides an accurate study of the spin-1/2 relativistic particle in a magnetic field in NC phase space By detailed calculation we find that the Dirac equation of the relativistic particle in a magnetic field in noncommutative space has similar behaviour to what happens in the Landau problem in commutative space even if an exact map does not exist By solving the Dirac equation in NC phase space, we not only obtain the energy level of the spin-1/2 relativistic particle in a magnetic field in NC phase space but also explicitly offer some additional terms related to the momentum-momentum non-commutativity
42 citations
TL;DR: The China Spallation Neutron Source (CSNSNSNS) is a large scientific facility with the main purpose of serving multidisciplinary research on material characterization using neutron scattering techniques as mentioned in this paper.
Abstract: The China Spallation Neutron Source (CSNS) is a large scientific facility with the main purpose of serving multidisciplinary research on material characterization using neutron scattering techniques. The accelerator system is to provide a proton beam of 120 kW with a repetition rate of 25 Hz initial...
42 citations
TL;DR: In this paper, the decay channel Ψ' → π+π− J/Ψ(J/Ω → γp) was studied using a sample of 1.06 × 108 Ω' events collected by the BESIII experiment at BEPCII.
Abstract: The decay channel Ψ' → π+π− J/Ψ(J/Ψ → γp) is studied using a sample of 1.06 × 108 Ψ' events collected by the BESIII experiment at BEPCII. A strong enhancement at threshold is observed in the p invariant mass spectrum. The enhancement can be fitted with an S-wave Breit–Wigner resonance function with a resulting peak mass of M = 1861+6−13 (stat)+7−26 (syst) MeV/c2 and a narrow width that is Γ < 38 MeV/c2 at the 90% confidence level. These results are consistent with published BESII results. These mass and width values do not match with well established mesons.
42 citations
TL;DR: In this paper, the Standard Model predictions for g-2 of the muon and for the hadronic contributions to the running of the QED coupling, Δα(5)had(M2Z), were updated.
Abstract: We update our Standard Model predictions for g-2 of the muon and for the hadronic contributions to the running of the QED coupling, Δα(5)had(M2Z). Particular emphasis is put on recent changes in the hadronic contributions from new data in the 2π channel and from the energy region just below 2 GeV.
41 citations
TL;DR: In this article, the Casas-Ibarra parametrization of the Dirac neutrino mass matrix MD in terms of an orthogonal matrix O and the diagonal mass matrices of light and heavy Majorana neutrinos in the type-I seesaw mechanism was investigated.
Abstract: The Casas–Ibarra parametrization is a description of the Dirac neutrino mass matrix MD in terms of the neutrino mixing matrix V, an orthogonal matrix O and the diagonal mass matrices of light and heavy Majorana neutrinos in the type-I seesaw mechanism. Because MD†MD is apparently independent of V but dependent on O in this parametrization, a number of authors have claimed that unflavored leptogenesis has nothing to do with CP violation at low energies. Here we question this logic by clarifying the physical meaning of O. We establish a clear relationship between O and the observable quantities, and find that O does depend on V. We show that both unflavored leptogenesis and flavored leptogenesis have no direct connection with low-energy CP violation.
34 citations
TL;DR: In this paper, the dE/dx measurement in the drift chamber of the Beijing Spectrometer (BES) has been studied for the identification of charged parti at the Beijing Electron-Positron Collider (BEPC).
Abstract: The Beijing Spectrometer Ⅲ (BESⅢ) is a general-purpose detector used for the study of τ-charm physics at the Beijing Electron-Positron Collider Ⅱ (BEPCⅢ) This paper presents our studies of the dE/dx measurement in the drift chamber of BESⅢ, which is important for the identification of charged parti
33 citations
TL;DR: In this paper, the absorption and emission of different components of a ternary liquid scintillator (Linear Alkyl Benzene (LAB) as the solvent, 2,5-diphenyloxazole (PPO) as fluor and p-bis-(o-methylstyryl)-benzene (bis-MSB) as wavelength shifter) are studied.
Abstract: Liquid scintillators are widely used as the neutrino target in neutrino experiments. The absorption and emission of different components of a ternary liquid scintillator (Linear Alkyl Benzene (LAB) as the solvent, 2,5-diphenyloxazole (PPO) as the fluor and p-bis-(o-methylstyryl)-benzene (bis-MSB) as wavelength shifter) are studied. It is shown that the absorption of this liquid scintillator is dominant by LAB and PPO at wavelengths less than 349 nm, and the absorption by bis-MSB becomes prevalent at the wavelength larger than 349 nm. The fluorescence quantum yields, which are the key parameters to model the absorption and re-emission processes in large liquid scintillation detectors, are measured.
TL;DR: In this article, a unified fission model combining with the phenomenological assault frequency has been carried out to investigate the proton-radioactivity half-lives of spherical proton emitters.
Abstract: The unified fission model (UFM) combining with the phenomenological assault frequency has been carried out to investigate the proton-radioactivity half-lives of spherical proton emitters. The results are in good agreement with the experimental data and other theoretical values, and newly observed spherical proton emitters have been analyzed. Finally, the effect of angular momentum transfer on half-life of proton emission has been discussed in detail and a formula can be used to describe this relationship.
TL;DR: In this article, the polarization effect on the spin symmetry for anti-Lambda spectrum in 16O + system has been studied in relativistic mean-field theory and the dominant components of the Dirac spinor for spin doublets are found to be near identical.
Abstract: The polarization effect on the spin symmetry for anti-Lambda spectrum in 16O + system has been studied in relativistic mean-field theory. The PK1 effective interaction is used for nucleon-meson couplings and G-parity symmetry with a reduction factor ξ = 0.3 is adopted for anti-Lambda-meson couplings. The energy differences between spin doublets in the anti-Lambda spectrum are around 0.10–0.73 MeV for p state. The dominant components of the Dirac spinor for the anti-Lambda spin doublets are found to be near identical. It indicates that the spin symmetry is still well-conserved against the polarization effect from the valence anti-Lambda hyperon, which leads to a highly compressed cold nucleus with the central density up to 2–3 times of saturated density.
TL;DR: In this article, trigger efficiencies at BESⅢ were determined for both the J/ψ and ψ data taking of 2009 for both dedicated runs and physics datasets.
Abstract: Trigger efficiencies at BESⅢ were determined for both the J/ψ and ψ data taking of 2009. Both dedicated runs and physics datasets are used; efficiencies are presented for Bhabha-scattering events, generic hadronic decay events involving charged tracks, dimuon events and ψ'→π+π,J/ψ, J/ψ→ l+l- events....
TL;DR: In this paper, the generalized analytic formulas of the scalar Feynman propagator and the spinor spinor propagator in position space in arbitrary (D + 1)-dimensional spacetime were derived.
Abstract: We correct an inaccurate result of previous work on the Feynman propagator in position space of a free Dirac field in (3 + 1)-dimensional spacetime; we derive the generalized analytic formulas of both the scalar Feynman propagator and the spinor Feynman propagator in position space in arbitrary (D + 1)-dimensional spacetime; and we further find a recurrence relation among the spinor Feynman propagator in (D+1)-dimensional spacetime and the scalar Feynman propagators in (D+1)-, (D−1)- and (D+3)-dimensional spacetimes.
TL;DR: In this article, the Bianchi identities satisfied by the Chern curvature were used to set up a gravitation theory in Berwald-Finsler space, which indicates that the local Lorentz invariance is violated.
Abstract: Finsler geometry is a natural and fundamental generalization of Riemann geometry. The Finsler structure depends on both coordinates and velocities. It is defined as a function on tangent bundle of a manifold. We use the Bianchi identities satisfied by the Chern curvature to set up a gravitation theory in Berwald-Finsler space. The geometric part of the gravitational field equation is nonsymmetric in general. This indicates that the local Lorentz invariance is violated.
TL;DR: In this paper, the light yield of a Linear Alkl Benzene (LAB) based liquid scintillator (LAB as the solvent, 3 g/L 2, 5 diphe-nyloxazole (PPO) as fluor and 15 mg/L p-bis-(o-methylstyryl)-benzene (bis-MSB) as the λ-shifter) was studied by measuring the light yields as a function of the nitrogen bubbling time.
Abstract: The oxygen quenching effect in a Linear Alkl Benzene (LAB) based liquid scintillator (LAB as the solvent, 3 g/L 2, 5 diphe-nyloxazole (PPO) as the fluor and 15 mg/L p-bis-(o-methylstyryl)-benzene (bis-MSB) as the λ-shifter) is studied by measuring the light yield as a function of the nitrogen bubbling time. It is shown that the light yield of the fully purged liquid scintillator is increased by 11% at room temperature and the room atmospheric pressure. A simple nitrogen bubbling model is proposed to describe the relationship between the relative light yield (oxygen quenching factor) and the bubbling time.
TL;DR: G4argo as mentioned in this paper is a GEANT4-based simulation package for the ARGO-YBJ detector, which incorporates in the simulation the true RPC time resolution and another 0.5 ns time uncertainty which is introduced from the offline calibration of TDC.
Abstract: 'G4argo', a GEANT4-based simulation package for the ARGO-YBJ detector, is described in this paper. G4argo incorporates in the simulation the true RPC time resolution and another 0.5 ns time uncertainty which is introduced from the offline calibration of TDC. In addition, the correct RPC geometry and the true materials for the ARGO-YBJ experimental hall are implemented. As a result, G4argo simulation shows a very good agreement with real data.
TL;DR: In this paper, the beam emittance of 238U and the isotopic abundance sensitivity of 236U were measured on the present beam line, using a 16-strip silicon detector.
Abstract: In order to measure the isotopic ratio of actinides, the upgrade of the accelerator mass spectrometry system at the Center for Isotopic Research on Cultural and Environmental heritage at the Second University of Naples, Italy, was performed. The beam emittance of 238U and the isotopic abundance sensitivity of 236U were measured on the present beam line. Utilizing a 16-strip silicon detector, the sensitivity of 236U/238U≈1×10−11 was obtained.
TL;DR: In this article, the light output functions for ST-401 and BC-408 plastic scintillators were measured using white neutron source produced by the 9Be(d, n) 10B reaction at the HI-13 Tandem Accelerator at China Institute of Atomic Energy (CIAE).
Abstract: The light output functions for protons of ST-401 and BC-408 plastic scintillators were measured using white neutron source produced by the 9Be(d, n) 10B reaction at the HI-13 Tandem Accelerator at China Institute of Atomic Energy (CIAE). The LOFs of plastic scintillators for protons in the energy range of 0.5–16.5 MeV were obtained by the time-of-flight (TOF) technique and an iterative procedure. Two parameters (kB and C) were deduced by fitting the experimental data.
TL;DR: In this paper, the B → (J/Ψ, ηc)K decays in the perturbative QCD (pQCD) factorization approach with the inclusion of the partial next-to-leading order (NLO) contributions.
Abstract: In this paper, we calculated the B → (J/Ψ, ηc)K decays in the perturbative QCD (pQCD) factorization approach with the inclusion of the partial next-to-leading order (NLO) contributions. With the inclusion of the significant enhancement from the NLO vertex corrections, the NLO pQCD predictions for the branching ratios agree with the data within 2σ errors: Br(B0 → J/ΨK0) = 5.2+3.5−2.8×10−4, Br(B+ → J/ΨK+) = 5.6+3.7−2.9×10−4, Br(B0 → ηcK0) = 5.5+2.3−2.0×10−4, Br(B+ → ηcK+) = 5.95.2+2.5−2.1×10−4.
TL;DR: In this paper, the authors used daya bay RPCs operating in streamer mode to investigate gas mixtures of at least 50% argon, at most 6% isobutane, and with small amounts of SF6.
Abstract: This study uses Daya Bay RPCs operating in streamer mode to investigate gas mixtures of at least 50% argon, at most 6% isobutane, and with small amounts of SF6. Isobutane is reduced to 2% without degradation of performance, and SF6 reduces the noise rate and current, as well as the signal size. This study provides quantitative relationships between basic RPC operating parameters and various gas compositions.
TL;DR: In this article, the mass-loaded flux tube model was used to model the dynamics of mesons and baryons containing a c quark and the spectrum of charmed (D) and charmed strange (Ds) mesons was computed.
Abstract: Heavy-light hadrons are studied in a mass loaded flux tube model. The study indicates that the dynamics of mesons and baryons containing a c quark is described well by the mass loaded flux tube. The hypothesis of good diquark-antiquark degeneracy is found reasonable in heavy-light quark systems. The spectrum of charmed (D) and charmed strange (Ds) mesons is systematically computed. D and Ds in 1D multiplets are predicted to have lower masses in comparison with other theoretical predictions. The predicted masses of the 1−(13D1) and the 3−(13D3) Ds agree well with those of recently observed Ds1(2700)± and DsJ(2860), respectively.
TL;DR: In this paper, the CP-averaged branching ratio for B → K 0* (1430)η(') decays in the framework of the perturbative QCD (pQCD) approach.
Abstract: Based on the assumption of two-quark structure of the scalar meson K0* (1430), we calculate the CP-averaged branching ratios for B → K0* (1430)η(') decays in the framework of the perturbative QCD (pQCD) approach here. We perform the evaluations in two scenarios for the scalar meson spectrum. We find that: (a) the pQCD predictions for Br(B → K0*(1430)η(') which are about 10−5–10−6, basically agree with the data within large theoretical uncertainty; (b) the agreement between the pQCD predictions and the data in Scenario I is better than that in Scenario II, which can be tested by the forthcoming LHC experiments; (c) the annihilation contributions play an important role for these considered decays.
TL;DR: In this article, a common superconducting electron linac for hard X-ray XFEL and ERL was proposed to share the advantages of the X-FEL beam with ERL beam and save the construction operation budget.
Abstract: The linac based XFEL and ERL are advanced (or, say, 4(th) generation) light sources, with different electron beam parameters and different advantages. However, the linac used for XFEL and ERL should provide very advanced beams with high energy, high peak and/or average current, very low emittance and low energy spread, thus making the linac very complicated and expensive. To share the XFEL and ERL advantages and save the construction-operation budget, a proposal of using a common superconducting electron linac for hard X-ray XFEL and ERL is described in this paper. The interactions between the XFEL and ERL beams via the accelerating structure are studied and the result is positive.
TL;DR: In this article, the generalized Bopp's shift has a symmetric representation and one can easily and straightforwardly define the star product on NC phase space and define non-commutative Lorentz transformations both on NC space and NC phase spaces.
Abstract: First a description of 2+1 dimensional non-commutative (NC) phase space is presented, and then we find that in this formulation the generalized Bopp's shift has a symmetric representation and one can easily and straightforwardly define the star product on NC phase space. Then we define non-commutative Lorentz transformations both on NC space and NC phase space. We also discuss the Poincare symmetry. Finally we point out that our NC phase space formulation and the NC Lorentz transformations are applicable to any even dimensional NC space and NC phase space.
TL;DR: In this article, a combined fit to the BABAR and Belle measurements of the e+e− → π+π− and f0(980) cross sections for center-of-mass energy between threshold and 3.0 GeV was performed.
Abstract: A combined fit is performed to the BABAR and Belle measurements of the e+e− → π+π− and f0(980) cross sections for center-of-mass energy between threshold and 3.0 GeV. The resonance parameters of the (1680) and Y(2175) are determined. The mass is (1681+10−12) MeV/c2 and the width is (221+34−24) MeV/c2 for the 43(1680), and the mass is (2117+59−49) MeV/c2 and the width is (164+69−80) MeV/c2 for the Y(2175). This information will shed light on the understanding of the nature of the excited and Y states observed in e+e− annihilation.
TL;DR: In this paper, a simple yet feasible method to accurately measure the projected coordinate origin was proposed, which was established on the basis of the theory that the projection of a spherical object in the cone-beam field is an ellipse.
Abstract: In order to determine the projected coordinate origin in the cone-beam CT scanning system with respect to the Feldkamp-Davis-Kress (FDK) algorithm, we propose a simple yet feasible method to accurately measure the projected coordinate origin. This method was established on the basis of the theory that the projection of a spherical object in the cone-beam field is an ellipse. We first utilized image processing and the least square estimation method to get each major axis of the elliptical Digital Radiography (DR) projections of a group of spherical objects. Then we determined the intersection point of the group of major axis by solving an over-determined equation set that was composed by the major axis equations of all the elliptical projections. Based on the experimental results, this new method was proved to be easy to implement in practical scanning systems with high accuracy and anti-noise capability.
TL;DR: In this paper, a rainbow-ladder truncation to the quark Dyson-Schwinger equation is used to arrive at a unified description of mesons and baryons by solving Bethe-Salpeter and covariant Faddeev equations, respectively.
Abstract: Employing an approach based on the Green functions of Landau-gauge QCD, some selected results from a calculation of meson and baryon properties are presented. A rainbow-ladder truncation to the quark Dyson–Schwinger equation is used to arrive at a unified description of mesons and baryons by solving Bethe–Salpeter and covariant Faddeev equations, respectively.
TL;DR: In this paper, a review of recent progress in the study of the XYZ particles at Belle is presented, focusing on studies with charmonium and one or more light mesons in the final states.
Abstract: In this paper, I review recent progress in the study of the XYZ particles at Belle. I only focus on studies with charmonium and one or more light mesons in the final states. This covers the X(3872), X(3915), Y(4140), X(4350), and the charged Z states.