Results 1 - 10 of 1601
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[en] In the framework of the soft-collinear effective theory, we demonstrate that the leading-power heavy-to-light baryonic form factors at large recoil obey the heavy quark and large energy symmetries. Symmetry breaking effects have several origins but all of them are suppressed by Λ/mb or Λ/E, where Λ is the hadronic scale, mb is the b quark mass and E∝mb is the energy of light baryon in the final state. Including the energy release dependence, we derive the scaling law for form factors ξΛ,p∝Λ2 /E2, which is in accordance with the implication from the experimental measurement on the branching ratio of Λb → pπ-. At leading order in αs, the leading-power baryonic form factors can factorize into the soft and collinear matrix elements without encountering any divergence. A leading-power factorization formula for nonleptonic b-baryon decays is also established. (orig.)
[en] In this work, I suggest a new way for determining the CKM angle γ via B decays into a scalar/tensor meson without any hadronic uncertainty. The proposed idea makes profits of the two triangles formed by the B±→(D0, anti D0,D0CP)K*±0(2)(1430) decay amplitudes. The advantages in it are large CP asymmetries and the avoidance of the use of doubly Cabibbo-suppressed D decays. Branching ratios of B±→(D0, anti D0,D0CP)K*±0(2)(1430) are estimated to have the order 10-6-10-5 and therefore measurable by the ongoing LHCb experiment and future experimental facilities. The usefulness of other related channels, for instance the neutral Bd decays into DK*0(2)(1430) and Bs→(D0, anti D0)M (M=f0(980),f0(1370),f'2(1525),f1(1285),f1(1420),h1(1180)), the B→D-+a±0,2 for the extraction of γ+2β and the Bs→D-+K*±0,2 to access γ+2βs, is also discussed in brevity.
[en] In this paper we have shown that due to a critical field, the patterns growing in the screened Laplacian field will be affected. When the critical field is zero, there is a transition from a dense growing to single branch of aggregate. At a higher critical field, the pattern shows a spiky-type aggregate, and for a small critical field the transition is cut. For an intermediate critical field, the result shows that below the transition, there no dense structure. (author). 9 refs, 2 figs
[en] The Wire Position Monitoring System (WPM) will track changes in the transverse position of LCLS Beam Position Monitors (BPMs) to 1(micro)m over several weeks. This position information will be used between applications of beam based alignment to correct for changes in component alignment. The WPM system has several requirements. The sensor range must be large enough so that precision sensor positioning is not required. The resolution needs to be small enough so that the signal can be used to monitor motion to 1(micro)m. The system must be stable enough so that system drift does not mimic motion of the component being monitored. The WPM sensor assembly consists of two parts, the magnetic sensor and an integrated lock-in amplifier. The magnetic sensor picks up a signal from the alternating current in a stretched wire. The voltage v induced in the sensor is proportional to the wire displacement from the center of the sensor. The integrated lock-in amplifier provides a DC output whose magnitude is proportional to the AC signal from the magnetic sensor. The DC output is either read on a digital voltmeter or digitized locally and communicated over a computer interface.
[en] We propose a new way for determining the CP violation angle γ. The suggested method is to use the two triangles formed by the decay amplitudes of B±→(D0, anti D0,D0CP)K*±0(2)(1430). The advantages are that large CP asymmetries are expected in these processes and only singly Cabibbo-suppressed D decay modes are involved. Measurements of the branching fractions of the neutral Bd decays into DK*0(2)(1430) and the time-dependent CP asymmetries in Bs→(D0, anti D0)M (M=f0(980),f0(1370),f2'(1525),f1(1285),f1(1420),h1(1180)) provide an alternative way to extract the angle γ, which will increase the statistical significance. No knowledge of the resonance structure in this method is required and therefore the angle γ can be extracted without any hadronic uncertainty. (orig.)
[en] We calculate the Drell-Yan production cross sections and differential distributions in the transverse momentum and rapidity of the JPC=1-- exotic hadrons φ(2170), X(4260) and Yb(10890) at the hadron colliders LHC and the Tevatron. These hadrons are tetraquark (four-quark) candidates, with a hidden s anti s, c anti c and b anti b quark pair, respectively. In deriving the distributions and cross sections, we include the order αs QCD corrections, resum the large logarithms in the small transverse momentum region in the impact-parameter formalism, and use the state of the art parton distribution functions. Taking into account the data on the production and decays of these vector hadrons from the e+e- experiments, we present the production rates for the processes pp(anti p)→ φ(2170)(→ φ(1020)π+π- → K+K-π+π-)+.., pp(anti p)→ X(4260)(→ J/ψπ+π- → μ+μ-π+π-)+.., and pp(anti p)→ Yb(10890)(→ (Υ(1S), Υ(2S), Υ(3S))π+π- → μ+μ-π+π-)+.. Their measurements at the hadron colliders will provide new experimental avenues to explore the underlying dynamics of these hadrons. (orig.)
[en] Numerical simulations of a 2D biharmonic equation ∇4u = 0 show that a transition from dense to multibranched growth is a consequence of long-range coupling between displacements on the patter formation of fractal aggregates. (author). 7 refs, 2 figs
[en] Nanocrystalline CuxS (x=1, 2) thin films were deposited by asynchronous-pulse ultrasonic spray pyrolysis (APUSP) technique on glass from CuCl2 and thiourea at relatively low temperature without any complexing agent. The deposited films chemically close to CuS were found to be polycrystalline phases, while the Cu2S films were a mixture of amorphous and polycrystalline as well. The crystalline phase of particles was highly depended on the molar ratio of thiourea to CuCl2 and the pyrolysis temperature. The growth of CuxS thin films was controlled successfully by the improved APUSP method. Characterization of the films has been carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. XRD and XPS analysis showed stoichiometric CuxS (covellite CuS and chalcolite Cu2S). Raman shifts of the films were measured at 474 cm-1 (CuS) and 472 cm-1 (Cu2S)
[en] We present a tetraquark interpretation of the charged bottomonium-like states Zb±(10610) and Zb±(10650), observed by the Belle collaboration in the π±Υ(nS) (n=1,2,3) and π±hb(mP) (m=1,2) invariant mass spectra from the data taken near the peak of the Υ(5S). In this framework, the underlying processes involve the production and decays of a vector tetraquark Yb(10890), e+e-→Yb(10890)→[Zb±(10610)pi-+, Zb±(10650)π-+] followed by the decays [Zb±(10610), Zb±(10650)]→π± Υ(nS), π±hb(mP). Combining the contributions from meson loops and from an effective Hamiltonian, we are able to reproduce the observe masses of the Zb±(10610) and Zb±(10650). Our formalism implies mixing between the mass eigenstates and the tetraquark spin states. The analysis presented here is in agreement with the Belle data and provides crucial tests of the tetraquark hypothesis. (orig.)