Resonant formation of d&mgr;t molecules in deuterium: An atomic beam measurement of muon catalyzed dt fusion

Resonant formation of d&mgr;t molecules in collisions of muonic tritium ( &mgr;t) on D2 was investigated using a beam of &mgr;t atoms, demonstrating a new direct approach in muon catalyzed fusion studies. Strong epithermal resonances in d&mgr;t formation were directly revealed for the first time. From the time-of-flight analysis of 2036+/-116 dt fusion events, a formation rate consistent with 0.73+/-(0.16)(meas)+/-(0.09)(model) times the theoretical prediction was obtained. For the largest peak at a resonance energy of 0.423+/-0.037 eV, this corresponds to a rate of (7.1+/-1.8)x10(9) s(-1), more than an order of magnitude larger than those at low energies.     

Theoretical study of the stereodynamics of the He＋HD^＋ reaction

This paper investigates the stereodynamics of the reaction He+HD+ by the quasi-classical trajectory(QCT) method using the most accurate AQUILANTI surface [Aquilanti et al 2000 Mol.Phys.98 1835].The distribution P(φr) of dihedral angle and the distribution P(θr) of angle between k and j have been presented at three different collision energies.Four generalized polarization-dependent differential cross-sections(2π/σ)(dσ00/dωt),(2π/σ)(dσ20/dωt),(2π/σ)(dσ22+/dωt),(2π/σ)(dσ21 /dωt) are also calculated.Some interesting results are obtained from the comparison of the stereodynamics of the title reaction at different collision energies.     

HD as a probe for detecting mass variation on a cosmological time scale

The strong electronic absorption systems of the B1 Sigma u+-X1 Sigma g+ Lyman and the C1Pi u-X1 Sigma g+ Werner bands can be used to probe possible mass-variation effects on a cosmological time scale from spectra observed at high redshift, not only in H2 but also in the second most abundant hydrogen isotopomer HD. High resolution laboratory determination of the most prominent HD lines at extreme ultraviolet wavelengths is performed at an accuracy of delta lambda/lambda approximately 5 x 10(-8), forming a database for comparison with astrophysical data. Sensitivity coefficients Ki = d ln lambda i/d ln mu are determined for HD from quantum ab initio calculations as a function of the proton-electron mass ratio mu. Strategies to deduce possible effects beyond first-order baryon/lepton mass ratio deviations are discussed.     

Search for the flavor-changing neutral current decay B0s--> mu(+) mu(-) in pp Collisions at sqrt[s] = 1.96 TeV with the D0 detector

We present the results of a search for the flavor-changing neutral current decay B(0)(s)--> mu(+) mu(-) using a data set with integrated luminosity of 240 pb(-1) of pp collisions at sqrt[s] = 1.96 TeV collected with the D0 detector in run II of the Fermilab Tevatron collider. We find the upper limit on the branching fraction to be B(B(0)(s)--> mu(+) mu(-)) < or= 5.0 x 10(-7) at the 95% C.L. assuming no contributions from the decay B(0)(d)--> mu(+) mu(-) in the signal region. This limit is the most stringent upper bound on the branching fraction B(0)(s)--> mu(+) mu(-) to date.     

Measurement of semileptonic branching fractions of B mesons to narrow D** states

Using the data accumulated in 2002-2004 with the D0 detector in proton-antiproton collisions at the Fermilab Tevatron collider with a center-of-mass energy of 1.96 TeV, the branching fractions of the decays B --> D0(1)(2420)mu+ vmuX and B --> D2(*0)(2460)mu+ vmuX and their ratio have been measured: B(b --> B) x B(B --> D0(1)mu+ vmuX) x B(D0(*0) --> D*- pi+) = [0.087 +/- 0.007(stat) +/- 0.014(syst)]%; B(b --> B) x B(B --> D2(*0) mu+ vmuX) x B(D2(*0) --> D*- pi+) = [0.035 +/- 0.007(stat) +/- 0.008(syst)]% and [B(B --> D2(*0)mu+ vmuX) x B(D2(*0) --> D*- pi+)]/[B(B --> D0(1)mu+ vmuX) x B(D0(1) --> D*- pi+)] = 0.39 +/- 0.09(stat) +/- 0.12 (syst), where the charge conjugated states are always implied.     

Measurement of the B0s lifetime in the exclusive decay channel B0s-->J/psiphi

Using the exclusive decay B0s-->J/psi(mu+mu-)phi(K+K-), we report the most precise single measurement of the B0s lifetime. The data sample corresponds to an integrated luminosity of approximately 220 pb(-1) collected with the D0 detector at the Fermilab Tevatron Collider in 2002-2004. We reconstruct 337 signal candidates, from which we extract the B0s lifetime, tau(B0s)=1.444(+0.098)(-0.090)(stat)+/-0.020(sys) ps. We also report a measurement for the lifetime of the B0 meson using the exclusive decay B0-->J/psi(mu+mu-)K*0(892)(K+pi-). We reconstruct 1370 signal candidates, obtaining tau(B0)=1.473(+0.052)(-0.050)(stat)+/-0.023(sys) ps, and the ratio of lifetimes, tau(B0s)/tau(B0)=0.980(+0.076)(-0.071)(stat)+/-0.003(sys).     

Autocorrelation exponent of conserved spin systems in the scaling regime following a critical quench

We study the autocorrelation function of a conserved spin system following a quench at the critical temperature. Defining the correlation length L(t) approximately t(1/z), we find that for times t' and t satisfying L(t')infinity limit, we show that lambda(')(c)=d+2 and phi=z/2. We give a heuristic argument suggesting that this result is, in fact, valid for any dimension d and spin vector dimension n. We present numerical simulations for the conserved Ising model in d=1 and d=2, which are fully consistent with the present theory.     

Evidence of two dimensionality in quasi-one-dimensional cobalt oxides

The quasi-one-dimensional (Q1D) cobalt oxides A(N + 2)Co(n + 1)O(3n + 3) (A = Ca, Sr, and Ba, n = 1 - infinity) were investigated by muon-spin spectroscopy under applied pressures of up to 1.1 GPa. The relationship between the onset Néel temperature T(on)(N) and the interchain distance (d(ic)), which increases monotonically with n, is well fitted by the formula T(N)/T(N,0) = (1 - d(ic)/d(ic,o)(beta), here for T(on)(N) approximately 100 K for Ca(3)Co(2)O(6) (n = 1) and approximately 15 for BaCoCoO(3) (n = infinity at ambient P. The T(on)(N) - d(ic) curve also predicts a large dependence of Y(N) for the compounds with n > or = 5, i.e., in the vicinity of , while the compounds show only a very small effect. Indeed, our high-pressure mu(+) results show that of BaCoO(3) is enhanced by with a slope of 2.2 K(Gpa), whereas no detectable changes by P for both Ca(3)Co(2)O(6) and Sr(4)Co(3)O(9) (n = 2). This clearly confirms the role of the 2D-antiferromagnetic interaction on T(on)(N) in the Q1D cobalt oxides.     

Measurement of the Lambda0b lifetime in the decay lambda0b--> J/psiLambda0 with the D0 detector

We present measurements of the Lambda(0)(b) lifetime in the exclusive decay channel Lambda(0)(b)--> J/psiLambda(0), with J/psi--> mu(+)mu(-) and Lambda(0)--> ppi(-), the B0 lifetime in the decay B0-->J/psiK(0)(S) with J/psi--> mu(+)mu(-) and K(0)(S)-->pi(+)pi(-), and the ratio of these lifetimes. The analysis is based on approximately 250 pb(-1) of data recorded with the D0 detector in pp collisions at sqrt[s] = 1.96 TeV. The Lambda(0)(b) lifetime is determined to be tau(Lambda(0)(b)) = 1.22(+0.22)(-0.18)(stat) +/- 0.04(syst) ps, the B0 lifetime tau(B0) = 1.40(+0.11)(-0.10)(stat) +/- 0.03(syst) ps, and the ratio tau(Lambda(0)(b))/tau(B0) = 0.87(+0.17)(-0.14)(stat) +/- 0.03(syst). In contrast with previous measurements using semileptonic decays, this is the first determination of the Lambda(0)(b) lifetime based on a fully reconstructed decay channel.     

Measurement of the Bs(0) lifetime using semileptonic decays

We report a measurement of the Bs(0) lifetime in the semileptonic decay channel Bs(0) --> Ds- mu+ nuX (and its charge conjugate), using approximately 0.4 fb(-1) of data collected with the D0 detector during 2002-2004. Using 5176 reconstructed Ds- mu+ signal events, we have measured the Bs(0) lifetime to be tau(Bs(0))=1.398+/-0.044(stat)(-0.025)(+0.028)(syst) ps. This is the most precise measurement of the Bs(0) lifetime to date.     

Initial gluon multiplicity in heavy-ion collisions

The initial gluon multiplicity per unit area per unit rapidity, dN/L2/d eta, in high energy nuclear collisions, is equal to f(N)(g(2)mu L) (g(2)mu)(2)/g(2), with mu(2) proportional to the gluon density per unit area of the colliding nuclei. For an SU(2) gauge theory, we compute f(N)(g(2)mu L) = 0.14 +/- 0.01 for a wide range in g(2)mu L. Extrapolating to SU(3), we predict dN/L2/d eta for values of g(2)mu L relevant to the Relativistic Heavy Ion Collider and the Large Hadron Collider. We compute the initial gluon transverse momentum distribution, dN/L2/d(2)k( perpendicular), and show it to be well behaved at low k( perpendicular).     

Muon catalyzed fusion in deuterium gas

We present the results of an experiment performed at PSI to investigate muon catalyzed fusion in pure deuterium gas of 5% density (LHD) at temperatures ranging from 28 K to 350 K. Using a new high pressure ionization chamber the reactions dd → n + ³He and dd → p+t were observed with 100% detection efficiency. The rates of dμd formation were measured with the absolute precision of 1% and the μd spin-flip rates with 0.5%. The temperature dependence of molecular formation and spin-flip rates display pronounced resonance structures. A preliminary fit based on the Vesman mechanism of resonant muonic molecule formation was carried out yielding a dd fusion rate of 3.5·10⁸ s^-1 and a hfs splitting energy of 24.3 meV, both in good agreement with the theory. This revised version was published online in August 2006 with corrections to the Cover Date.     

Extracting weak phase information from B-->V1V2 decays

We describe a new method for extracting weak, CP-violating &Dmacr;phase information, with no hadronic uncertainties, from an angular analysis of B-->V1V2 decays, where V1 and V2 are vector mesons. The quantity sin (2)(2beta+gamma) can be cleanly obtained from the study of decays such as B(0)(d)(t)-->D*+/-rho(-/+), D(*+/-)a(-/+)(1), D(;) *0K(;) (*0), etc. Similarly, one can use B(0)(s)(t)-->D(*+/-)(s)K*-/+ to extract sin (2)gamma. There are no penguin contributions to these decays. It is possible that sin (2)(2beta+gamma) will be the second function of CP phases, after sin2beta, to be measured at B factories.     

Search for [corrected] B0(s) --> mu+ mu- and B0(d) [corrected] --> mu + mu- decays in pp collisions with CDF II

We report on a search for B0(s) --> mu+ mu- and B0(d) --> mu + mu- decays in pp collisions at square root(s) = 1.96 TeV using 364 pb(-1) of data collected by the CDF II detector at the Fermilab Tevatron Collider. After applying all selection requirements, we observe no candidates inside the B0(s) or B0(d) mass windows. The resulting upper limits on the branching fractions are B(B0(s) --> mu+ mu-) < 1.5 x 10(-7) and B(B0(d) --> mu+ mu-) < 3.9 x 10(-8) at 90% confidence level.     

Improved measurement of B(D+ --> mu+nu) and the pseudoscalar decay constant fD+

We extract a relatively precise value for the decay constant of the meson by measuring B(D+ --> mu+nu) = (4.40 +/-0.66(+0.09)(-0.12) x 10(-4) using 281 pb(-1) of data taken on phi(3770) the resonance with the CLEO-c detector. We find fD+ = (222.6 +/- 16.7(+2.8)(-3.4)) MeV, and compare with current theoretical calculations. We also set a 90% confidence upper limit on B(D+e+nu)< 2.4 x 10(-5) which constrains new physics models.     

Bond-shift rearrangement in solid Li(3)P(7)(monoglyme)(3): a (31)P MAS NMR study.

The (31)P MAS NMR spectrum of solid Li(3)P(7)(monoglyme)(3) has been reinvestigated over a wide temperature range (-70 to +77 degrees C) and under conditions of better resolution (Larmor frequency of 162 MHz and spinning rate of approximately 30 kHz) than previously measured (121 MHz and 13 kHz). At low temperatures three spinning sideband (ssb) manifolds are observed: a singlet (centered at -45 ppm relative to 85% H(3)PO(4)) due to the apical atom (A) of the P(7)-cage trianion; a 1 : 1 : 1 triplet (at -110, -117, and -124.5 ppm) due to the negatively charged equatorial (E) atoms, and a one to two doublet (at -161 and -168.5 ppm) due to the basal (B) atoms. These results are consistent with the P(7) cage having nearly, but not perfect, C(3v) symmetry. The compound appears to be well ordered in the solid state with very little structural dispersity. On heating, the NMR lines broaden and eventually coalesce into a single ssb manifold. This behavior is ascribed to bond-shift rearrangement similar to the Cope rearrangement in bullvalene. A MAS 2D exchange experiment and a quantitative analysis of the 1D NMR lineshapes indicate that, unlike in solution where the rearrangement involves a single bond shift at a time, in the solid the process involves a succession of two bond shifts: The first leads to an intermediate species in which the rearranged P(7) cage is inverted, while in the subsequent step a second bond shift takes place that also restores the original orientation of the cage in the lattice. The overall effect of the double bond shift is equivalent to cyclic permutation of the phosphorus atoms within the five member rings of the P(7)-cage. The quantitative analysis of the dynamic lineshapes shows that this cyclic permutation proceeds at a different rate in one ring (k(d)(1)) than in the other two (k(d)(2,3)). The kinetic parameters for these processes are E(a)(1)=18.7 kJ/mol, E(a)(2,3)=58.0 kJ/mol, k(d)(1)(17 degrees C)=k(d)(2,3)(17 degrees C)=10(4) s(-1). No indications for independent threefold molecular jumps of the P(7) cage were found.     

Ca+CH_3I→CaI+CH_3反应的矢量相关研究(英文)

本文采用准经典轨线方法,在LEPS势基础上计算了Ca+CH3I→CaI+CH3在不同碰撞能下的矢量相关计算了质心系中四个广义极化微分反应截面(2π/σ)(dσ00/dωt),(2π/σ)(dσ20/dωt),(2π/σ)(dσ22+/dωt),(2π/σ)(dσ21-/dωt),k-j′两矢量相关的P(θr)分布、k-k′-j′三矢量相关的极角分布P(φr)以及用θr和φr表示的产物转动角动量的空间分布P(θr,φr).     

Stability of spikes in the shadow Gierer-Meinhardt system with Robin boundary conditions

We consider the shadow system of the Gierer-Meinhardt system in a smooth bounded domain Omega subset R(N),A(t)=epsilon(2)DeltaA-A+A(p)/xi(q),x is element of Omega, t>0, tau/Omega/xi(t)=-/Omega/xi+1/xi(s) integral(Omega)A(r)dx, t>0 with the Robin boundary condition epsilon partial differentialA/partial differentialnu+a(A)A=0, x is element of partial differentialOmega, where a(A)>0, the reaction rates (p,q,r,s) satisfy 10, r>0, s>or=0, 1or=0. We rigorously prove the following results on the stability of one-spike solutions: (i) If r=2 and 11 and tau sufficiently small the interior spike is stable. (ii) For N=1 if r=2 and 11 such that for a is element of (a(0),1) and mu=2q/(s+1)(p-1) is element of (1,mu(0)) the near-boundary spike solution is unstable. This instability is not present for the Neumann boundary condition but only arises for the Robin boundary condition. Furthermore, we show that the corresponding eigenvalue is of order O(1) as epsilon-->0.     

Measurements of the Decay KL-->e+ e- mu+ mu-

The KTeV experiment at Fermilab has isolated a total of 132 events from the rare decay K(L)-->e+ e- mu+ mu-, with an estimated background of 0.8 events. The branching ratio of this mode is determined to be [2.69+/-0.24(stat)+/-0.12(syst)]x10(-9), with a radiative cutoff of M(2)(ee mu mu)/M(2)(K)>0.95. The first measurement using this mode of the parameter alpha from the D'Ambrosio-Isidori-Portolès (DIP) model of the K(L)gamma*gamma* vertex yields a result of -1.59+/-0.37, consistent with values obtained from other decay modes. Because of the limited statistics, no sensitivity is found to the DIP parameter beta. We use this decay mode to set limits on CP and lepton violation.     

Interfacial reactions: mixed order kinetics and segregation effects

We study A-B reaction kinetics at a fixed interface separating A and B bulks. Initially, the number of reactions R(t) approximately tn(infinity)(A)n(infinity)(B) is second order in the far-field densities n(infinity)(A), n(infinity)(B). First order kinetics, governed by diffusion from the dilute bulk, onset at long times: R(t) approximately x(t)n(infinity)(A), where x(t) approximately t(1/z) is the rms molecular displacement. Below a critical dimension, d0) leads to anomalous decay of interfacial densities. Numerical simulations for z = 2 support the theory.