Study of e+e−→ppˉe^+e^- \rightarrow p\bar{p} in the vicinity of ψ(3770)\psi(3770)

Using 2917 $\rm{pb}^{-1}$ of data accumulated at 3.773~$\rm{GeV}$, 44.5~$\rm{pb}^{-1}$ of data accumulated at 3.65~$\rm{GeV}$ and data accumulated during a $\psi(3770)$ line-shape scan with the BESIII detector, the reaction $e^+e^-\rightarrow p\bar{p}$ is studied considering a possible interference between resonant and continuum amplitudes. The cross section of $e^+e^-\rightarrow\psi(3770)\rightarrow p\bar{p}$, $\sigma(e^+e^-\rightarrow\psi(3770)\rightarrow p\bar{p})$, is found to have two solutions, determined to be ($0.059\pm0.032\pm0.012$) pb with the phase angle $\phi = (255.8\pm37.9\pm4.8)^\circ$ ($<$0.11 pb at the 90% confidence level), or $\sigma(e^+e^-\rightarrow\psi(3770)\rightarrow p\bar{p}) = (2.57\pm0.12\pm0.12$) pb with $\phi = (266.9\pm6.1\pm0.9)^\circ$ both of which agree with a destructive interference. Using the obtained cross section of $\psi(3770)\rightarrow p\bar{p}$, the cross section of $p\bar{p}\rightarrow \psi(3770)$, which is useful information for the future PANDA experiment, is estimated to be either ($9.8\pm5.7$) nb ($<17.2$ nb at 90% C.L.) or $(425.6\pm42.9)$ nb

Two-pion Bose-Einstein correlations in central Pb-Pb collisions at sNN\sqrt{s_{\rm NN}} = 2.76 TeV

The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV at the Large Hadron Collider is presented. We observe a growing trend with energy now not only for the longitudinal and the outward but also for the sideward pion source radius. The pion homogeneity volume and the decoupling time are significantly larger than those measured at RHIC.Comment: 17 pages, 5 captioned figures, 1 table, authors from page 12, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/388

Suppression of charged particle production at large transverse momentum in central Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}} = 2.76 TeV

Inclusive transverse momentum spectra of primary charged particles in Pb-Pb collisions at $\sqrt{s_{_{\rm NN}}}$ = 2.76 TeV have been measured by the ALICE Collaboration at the LHC. The data are presented for central and peripheral collisions, corresponding to 0-5% and 70-80% of the hadronic Pb-Pb cross section. The measured charged particle spectra in $|\eta|<0.8$ and $0.3 < p_T < 20$ GeV/$c$ are compared to the expectation in pp collisions at the same $\sqrt{s_{\rm NN}}$, scaled by the number of underlying nucleon-nucleon collisions. The comparison is expressed in terms of the nuclear modification factor $R_{\rm AA}$. The result indicates only weak medium effects ($R_{\rm AA} \approx$ 0.7) in peripheral collisions. In central collisions, $R_{\rm AA}$ reaches a minimum of about 0.14 at $p_{\rm T}=6$-7GeV/$c$ and increases significantly at larger $p_{\rm T}$. The measured suppression of high-$p_{\rm T}$ particles is stronger than that observed at lower collision energies, indicating that a very dense medium is formed in central Pb-Pb collisions at the LHC.Comment: 15 pages, 5 captioned figures, 3 tables, authors from page 10, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/98

Asymptotic distribution of statistics based on quadratic entropy and bootstrapping

We investigate the asymptotic properties of some statistics based on quadratic entropy (QE), a notion introduced by Rao (Sankrya A 44 (1992) 1-21) as a general measure of variability in a population. Sample QE based on i.i.d. observations from a distribution function is defined and its asymptotic distribution is derived. The use of QE in the place of variance in analysis of diversity of cross classified data provides a generalization of ANOVA. We call this method ANOQE (analysis of quadratic entropy). The ANOQE statistic for testing equality of populations based on one-way classified data is constructed and its asymptotic and bootstrap distributions are derived

Mechanical strength enhancement of low temperature co-fired multilayer ceramic substrates by introducing residual stress

Two low temperature cofirable ceramic materials with thermal expansion coefficients (TEC) of 5.9 ppm/K and 6.6 ppm/K, respectively, were used in this work to introduce residual stress by the multilayer cofiring process. Theoretical calculation and finite element method (FEM) simulation were used to optimize the multilayered ceramic substrate composition design to obtain enhanced mechanical performance. Based on the failure condition of materials, the multilayered ceramic substrate has an optimal thickness ratio of the surface layers to the whole laminate (sandwich structure). Indentation method was used to measure the surface residual stresses and 3-point bending tests were used to measure the mechanical strength. Enhanced mechanical strength of 404 MPa can be obtained when the thickness ratio of surface layer to the whole laminate is 0.19

Thermodynamic, structural and elastic properties of Co3X (X = Ti, Ta, W, V, Al) compounds from first-principles calculations

Through first-principles calculations within the framework of density functional theory, we have computed the electronic structures, mechanical elastic properties and thermodynamic properties of a series of Co-based Co"3X (X = Ti, Ta, W, V and Al) intermetallic compounds with the cubic L1"2-type and hexagonal D0"1"9-type structures. The obtained lattice constants and formation energy are in good agreement with available experimental data. In terms of calculated mechanical elastic properties and Poisson's ratio, most of these Co"3X compounds are mechanically stable and exhibit a good ductile property. The calculations also have uncovered that the obtained elastic parameters including single-crystal elastic constants and polycrystalline moduli of Co"3X compounds hold a linearly increasing tr..

Thermodynamic, structural and elastic properties of Co3X (X = Ti, Ta, W, V, Al) compounds from first-principles calculations

Through first-principles calculations within the framework of density functional theory, we have computed the electronic structures, mechanical elastic properties and thermodynamic properties of a series of Co-based Co"3X (X = Ti, Ta, W, V and Al) intermetallic compounds with the cubic L1"2-type and hexagonal D0"1"9-type structures. The obtained lattice constants and formation energy are in good agreement with available experimental data. In terms of calculated mechanical elastic properties and Poisson's ratio, most of these Co"3X compounds are mechanically stable and exhibit a good ductile property. The calculations also have uncovered that the obtained elastic parameters including single-crystal elastic constants and polycrystalline moduli of Co"3X compounds hold a linearly increasing tr..