The Effect of SRS on Signal Power in Single-mode Silica Fiber in DWDM Optical Communication System with Equally Spaced Channels

Assuming that the Raman gain profile of silica fiber is a triangular function, we derive analytic solutions of N-channel steady-state forward SRS coupling wave equation with equal (but arbitrary) channel spacing. Considering the SRS cross coupling among N-channels, the analytic solutions are applicable to arbitrary signal light power. The results point out that the sequence mi=pi(z)/pi(0) [pi(z) and pi(0) is the power of signal light of i-th channel at transmission length z and 0, respectively. i=1,2,...N] maintains a geometric progression with the common ratio q in the transmission process. The common ratio q varies as a exponential function of the effective transmission length, the sum of input light power and the channel spacing, respectively.     

The Effect of SRS on Signal Power in Single mode Silica Fiber in DWDM Optical Communication System with Equally Spaced Channels

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Double helicity asymmetry in inclusive midrapidity pi0 production for polarized p+p collisions at square root s = 200 GeV

We present a measurement of the double longitudinal spin asymmetry in inclusive pi(0) production in polarized proton-proton collisions at sqrt[s]=200 GeV. The data were taken at the Relativistic Heavy Ion Collider with average beam polarizations of 0.27. The measurements are the first in a program to study the longitudinal spin structure of the proton, using strongly interacting probes, at collider energies. The asymmetry is presented for transverse momenta 1-5 GeV/c at midrapidity, where next-to-leading-order perturbative quantum chromodynamic (NLO pQCD) calculations well describe the unpolarized cross section. The observed asymmetry is small and is compared to a NLO pQCD calculation with a range of polarized gluon distributions.     

Phonon-assisted tunneling in the quantum regime of Mn12 acetate

Longitudinal or transverse magnetic fields applied on a crystal of Mn12 acetate allows one to observe independent tunnel transitions between m = -S+p and m = S-n-p ( n = 6-10, p = 0-2 in longitudinal field and n = p = 0 in transverse field). We observe a smooth transition (in longitudinal) from coherent ground-state to thermally activated tunneling. Furthermore, two ground-state relaxation regimes show a crossover between quantum spin relaxation far from equilibrium and near equilibrium, when the environment destroys multimolecule correlations. Finally, we stress that the complete Hamiltonian of Mn12 should contain odd spin operators of low order.     

Role of the spin anisotropy of the interchain interaction in weakly coupled antiferromagnetic Heisenberg chains

In quasi-one-dimensional(q1D) quantum antiferromagnets, the complicated interplay of intrachain and interchain exchange couplings may give rise to rich phenomena. Motivated by recent progress on field-induced phase transitions in the q1D antiferromagnetic(AFM) compound YbAlO_3, we study the phase diagram of spin-1/2 Heisenberg chains with Ising anisotropic interchain couplings under a longitudinal magnetic field via large-scale quantum Monte Carlo simulations,and investigate the role of the spin anisotropy of the interchain coupling on the ground state of the system. We find that the Ising anisotropy of the interchain coupling can significantly enhance the longitudinal spin correlations and drive the system to an incommensurate AFM phase at intermediate magnetic fields, which is understood as a longitudinal spin density wave(LSDW). With increasing field, the ground state changes to a canted AFM order with transverse spin correlations. We further provide a global phase diagram showing how the competition between the LSDW and the canted AFM states is tuned by the Ising anisotropy of the interchain coupling.     

Interaction of $F=2$ Spinor Bose Condensate with Driven External Magnetic Fields

We have studied the interaction of $F=2$ spinor Bose condensate with a combination of static and sinusoidal magnetic field $b_l(t)=b_0+b\cos(\omega t)$. We find that the tunneling current among spin 0 and spin $\pm1$, spin 0 and spin $\pm2$, spin $\pm1$ and spin $\pm2$ may exhibit the incremental oscillation behavior, which depends on the field parameters of the reduced amplitudes of the transverse and the longitudinal magnetic fields respectively. This means that the dynamics spin localization can be adjusted experimentally by selecting the less values of the reduced amplitudes of the transverse magnetic field $b_x/\omega$ and those of the longitudinal magnetic field $b/\omega$.     

Scaling and renormalization group in replica-symmetry-breaking space: evidence for a simple analytical solution of the Sherrington-Kirkpatrick model at zero temperature

Using numerical self-consistent solutions of a sequence of finite replica symmetry breakings (RSB) and Wilson's renormalization group but with the number of RSB steps playing a role of decimation scales, we report evidence for a nontrivial T-->0 limit of the Parisi order function q(x) for the Sherrington-Kirkpatrick spin glass. Supported by scaling in RSB space, the fixed point order function is conjectured to be q*(a)=sqrt[pi]/2 a/xi erf(xi/a) on 0 a at T =0 and xi approximately 1.13+/-0.01. Xi plays the role of a correlation length in a-space. q*(a) may be viewed as the solution of an effective 1D field theory.     

Nuclear spin relaxation rates in two-Leg spin ladders

Using the transfer-matrix density-matrix renormalization group method, we study the nuclear spin relaxation rate 1/T(1) in the two-leg s = 1 / 2 ladder as a function of the interchain (J( perpendicular)) and intrachain (J( parallel)) couplings. In particular, we separate the q(y) = 0 and pi contributions and show that the latter contribute significantly to the copper relaxation rate (63)(1/T(1)) in the experimentally relevant coupling and temperature range. We compare our results to both theoretical predictions and experimental measures on ladder materials.     

Antiferromagnetic d-electron exchange via a spin-singlet pi-electron ground state in an organic conductor

Electron spin resonance reveals the spin behavior of conduction (pi) and localized (d) electrons in beta-(BDA-TTP)2MCl4 (M=Fe, Ga). Both the Ga3+(S=0) and Fe3+(S=5/2) compounds exhibit a metal-insulator transition at 113 K with the simultaneous formation of a spin-singlet ground state in the pi electron system of the donor molecules. The behavior is consistent with charge ordering in beta-(BDA-TTP)2MCl4 at the metal-insulator transition. At 5 K, the Fe3+ compound orders antiferromagnetically, even though the pi electrons, which normally would facilitate magnetic exchange, are localized nonmagnetic singlets.     

Comments on “power-law falloff in the Kosterlitz-Thouless phase of a two-dimensional lattice Coulomb gas”

A simple argument is presented by which one can show that the critical inverse temperature _c of a two-dimensional Coulomb gas (standard or hard-core) with activityz satisfies , where in the low-activity limit. Previous results yield .     

Incommensurate magnetic ordering in Sr2Ru(1-x)TixO4

In Sr2RuO4 the spin excitation spectrum is dominated by incommensurate fluctuations at q = (0.3 0.3q(z)), which arise from Fermi-surface nesting. We show that upon Ti substitution, known to suppress superconductivity, a short range magnetic order develops with a propagation vector (0.307 0.307 1). In Sr2Ru0.91Ti0.09O4, the ordered moment points along the c direction. This finding shows that superconducting Sr2RuO4 is extremely close to an incommensurate spin density wave instability.     

Novel dynamic ccaling regime in hole-doped La2CuO4

Only 3% hole doping by Li is sufficient to suppress the long-range three-dimensional (3D) antiferromagnetic order in La2CuO4. The spin dynamics of such a 2D spin liquid state at T相似文献   

Study of B0 --> J/psiK(*)0pi(+)pi(-) decays with the collider detector at Fermilab

We report a study of the decays B0 --> J/psiK(*)0pi(+)pi(-), which involve the creation of a uu or dd quark pair in addition to a b -->c(cs) decay. The data sample consists of 110 pb(-1) of pp collisions at square root[s] = 1.8 TeV collected by the CDF detector at the Fermilab Tevatron collider during 1992-1995. We measure the branching fractions to be B(B0 --> J/psiK(*0)pi(+)pi(-)) = (6.6 +/- 1.9 +/- 1.1)x10(-4) and B(B0 --> J/psiK0pi(+)pi(-)) = (10.3 +/- 3.3 +/- 1.5)x10(-4). Evidence is seen for contributions from psi(2S)K(*)0, J/psiK0rho(0), J/psiK(*+)pi(-), and J/psiK1(1270).     

Measurement of longitudinal and rotating frame relaxation times through fully J-decoupled homonuclear spectra.

It is shown that fully J-decoupled homonuclear spectra involving Lorentzian lines can be readily obtained by straightforward processing of the 2D data arising from a conventional spin echo sequence (pi/2-t(1)/2-pi-t(1)/2-Acq(t(2))) used in the so-called J-resolved experiment. The method simply rests on power spectra with the drawback of lines having meaningless relative intensities. In principle, the experiment should also yield transverse relaxation times. Several tests demonstrate that this is not so, due to pulse imperfections and nonresolved long-range J couplings. Conversely, longitudinal and rotating frame relaxation times can be easily determined by means of an appropriate preparation period (for instance, a saturation-recovery period in the case of longitudinal relaxation) inserted before the 2D spin echo sequence. Since one is dealing with a single line per nucleus, relaxation measurements become reliable and accurate.     

Onset and saturation of the kink instability in a current-carrying line-tied plasma

An internal kink instability is observed to grow and saturate in a line-tied screw pinch plasma. Detailed measurements show that an ideal, line-tied kink mode begins growing when the safety factor q = (4pi2r2B(z))/(mu0I(p)(r)L) drops below 1 inside the plasma; the saturated state corresponds to a rotating helical equilibrium. In addition to the ideal mode, reconnection events are observed to periodically flatten the current profile and change the magnetic topology.     

Spin gap and string order parameter in the ferromagnetic spiral staircase heisenberg ladder: a quantum Monte Carlo study

We consider a spin-1/2 ladder with a ferromagnetic rung coupling J perpendicular and inequivalent chains. This model is obtained by a twist (theta) deformation of the ladder and interpolates between the isotropic ladder (theta=0) and the SU(2) ferromagnetic Kondo necklace model (theta = pi). We show that the ground state in the (theta, J perpendicular) plane has a finite string order parameter characterizing the Haldane phase. Twisting the chain introduces a new energy scale, which we interpret in terms of a Suhl-Nakamura interaction. As a consequence we observe a crossover in the scaling of the spin gap at weak coupling from delta/J parallel proportional, variant J perpendicular/J parallel for theta < theta c approximately 8 pi/9 to delta/J parallel proportional, variant (J perpendicular/J parallel)2 for theta > theta c. Those results are obtained on the basis of large scale quantum Monte Carlo calculations.     

Measurement of the charged pion electromagnetic form factor

Separated longitudinal and transverse structure functions for the reaction 1H(e,e(')pi(+))n were measured in the momentum transfer region Q2 = 0.6--1.6 (GeV/c)(2) at a value of the invariant mass W = 1.95 GeV. New values for the pion charge form factor were extracted from the longitudinal cross section by using a recently developed Regge model. The results indicate that the pion form factor in this region is larger than previously assumed and is consistent with a monopole parametrization fitted to very low Q2 elastic data.     

Spin-fermion model near the quantum critical point: one-loop renormalization group results

We consider spin and electronic properties of itinerant electron systems, described by the spin-fermion model, near the antiferromagnetic critical point. We expand in the inverse number of hot spots in the Brillouin zone, N, and present the results beyond the previously studied N = infinity limit. We found two new effects: (i) Fermi surface becomes nested at hot spots, and (ii) vertex corrections give rise to anomalous spin dynamics and change the dynamical critical exponent from z = 2 to z>2. To first order in 1/N we found z = 2N/(N-2) which for a physical N = 8 yields z approximately 2.67.     

Measurement of D0-D0 mixing parameters in D0 --> Ks pi+ pi- decays

We report a measurement of D0-D(0) mixing parameters in D(0) --> K(s)(0) pi(+) pi(-) decays using a time-dependent Dalitz-plot analysis. We first assume CP conservation and subsequently allow for CP violation. The results are based on 540 fb(-1) of data accumulated with the Belle detector at the KEKB e(+)e(-) collider. Assuming negligible CP violation, we measure the mixing parameters x = (0.80 +/- 0.29(-0.07-0.14)(+0.09+0.10))% and y = (0.33+/-0.24(-0.12-0.08)(+0.08+0.06))%, where the errors are statistical, experimental systematic, and systematic due to the Dalitz decay model, respectively. Allowing for CP violation, we obtain the CP-violating parameters |q / p| = 0.86(-0.29-0.03)(+0.30+0.06) +/- 0.08 and arg(q/p) = (-14(-18-3-4)(+16+5+2)) degrees .