The newly observed $$\Lambda _b(6072)^0$$ structure and its $$\rho $$-mode nonstrange partners

Inspired by the newly observed $$\Lambda _b(6072)$$Λb(6072) structure, we investigate its strong decay behaviors under various assignments within the $$^3P_0$$3P0 model. Compared with the mass and total decay width, our results suggest that the $$\Lambda _b(6072)$$Λb(6072) can be regarded as the lowest $$\rho $$ρ-mode excitation in $$\Lambda _b$$Λb family. Then, the strong decays of $$\rho $$ρ-mode nonstrange partners for the $$\Lambda _b(6072)$$Λb(6072) are calculated. It is found that the $$J^P=5/2^-$$JP=5/2-$$\Lambda _b$$Λb and $$\Lambda _c$$Λc states are relatively narrow, and mainly decay into the $$\Sigma _b^{(*)} \pi $$Σb(∗)π and $$\Sigma _c^{(*)} \pi $$Σc(∗)π final states, respectively. These two states have good potentials to be observed in future experiments, which may help us to distinguish the three-quark model and diquark model.

DATA TAKING STRATEGY FOR THE PHASE STUDY IN ψ′→K+K-

The study of the relative phase between strong and electromagnetic amplitudes is of great importance for understanding the dynamics of charmonium decays. The information of the phase can be obtained model-independently by fitting the scan data of some special decay channels, one of which is ψ′ →K+K-. To find out the optimal data taking strategy for a scan experiment in the measurement of the phase in ψ′ →K+ K-, the minimization process is analyzed from a theoretical point of view. The result indicates that for one-parameter fit, only one data taking point in the vicinity of a resonance peak is sufficient to acquire the optimal precision. Numerical results are obtained by fitting simulated scan data. Besides the results related to the relative phase between strong and electromagnetic amplitudes, the method is extended to analyze the fits of other resonant parameters, such as the mass and the total decay width of ψ′.

VECTOR AND AXIAL-VECTOR STRUCTURES OF THE Θ+

We present in this talk recent results of the vector and axial-vector transitions of the nucleon to the pentaquark baryon Θ+, based on the SU(3) chiral quark-soliton model. The results are summarized as follows: K*NΘ vector and tensor coupling constants turn out to be gK*NΘ ≃ 0.81 and fK*NΘ ≃ 0.84, respectively, and the KNΘ axial-vector coupling constant to be [Formula: see text]. As a result, the total decay width for Θ+ → NK becomes very small: ΓΘ→NK ≃ 0.71 MeV , which is consistent with the DIANA result ΓΘ→NK = 0.36 ± 0.11 MeV .

MEASUREMENTS OF THE W AND Z PRODUCTION CROSS SECTIONS TIMES THE LEPTONIC BRANCHING RATIOS AT THE FERMILAB TEVATRON

We report measurements of inclusive cross sections times branching ratios in electrons, muons or taus for W and Z bosons produced in [Formula: see text] collisions at 1.96 TeV using data collected with the DØ and CDF detectors in 2002-2004. Using the ratio of the cross sections times branching ratios for the W and Z bosons we also obtain constraints on the total decay width of the W boson.

DIRECT MEASUREMENT OF THE W WIDTH IN $p{\bar p}$ COLLISIONS AT $\sqrt{s} = 1.96~{\rm TEV}$

This paper describes a direct measurement of the W boson total decay width ΓW using the DØ detector at the Fermilab Tevatron Collider. The measurement uses an integrated luminosity of 177.3 pb-1, collected during the 2002-2003 run. The width is determined by normalizing the predicted signal and background transverse mass distributions to 75,285 W → eν candidates in the transverse mass region 50 < MT < 100 GeV and then fitting the predicted shape to the 625 candidates in the tail region 100 < MT < 200 GeV . The W width is determined to be ΓW = 2.011 ± 0.093 ( stat ) ± 0.107 ( syst ) GeV .

ELECTROWEAK MEASUREMENTS FROM RUN II AT THE TEVATRON

The CDF and DØ detectors were fully commissioned for physics running in Run II at the Tevatron [Formula: see text] collider in early 2002. Since then both experiments have collected data samples corresponding to an integrated luminosity of around ∫L=200 pb -1 at a [Formula: see text] centre-of-mass energy of [Formula: see text]. Datasets corresponding ∫L=120 pb-1 have been analyzed for physics so far. Recent electroweak measurements from Run II are reviewed. Cross section times branching ratio measurements (σ· Br ) are presented for the intermediate vector bosons (IVB's) in their leptonic decay modes: W→ℓν and Z→ℓ+ℓ-. For the first time, a combination of the σ· Br results from the CDF and DØ experiments is made; this includes using a consistent choice of the total inelastic [Formula: see text] cross section for the luminosity determinations of the two experiments. Quantities derived from these σ· Br values are also updated. These include: R ℓ the ratio of the σ· Br values for W and Z; Br (W→ℓν), the leptonic branching ratio of the W; and Γw, the total decay width of the W. Other measurements using events containing W and Z leptonic decays are presented, including studies that probe the QCD phenomenology of W/Z production and searches for events containing two intermediate vector bosons.

STUDY OF ηc PRODUCED IN γγ INTERACTIONS AT CLEO

Using the CLEO detector at CESR we have analyzed 13.4fb-1 of e+e- interactions which have yielded approximately 300 events from the process [Formula: see text] From this data sample we have obtained measurements of the ηc mass [2980.4±2.3(stat)±0.6(syst)] MeV and its total decay width [27.0±5.8(stat)±1.4(syst)] MeV. Furthermore, we have measured two-photon partial width of ηc to be [7.6±0.8(stat)±0.4(sys)±2.3(br)] keV, where the last error is due to the uncertainty of [Formula: see text].