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H. Guo

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Published work

29 published item(s)

preprint2026arXiv

Enhancing Train-Free Infinite-Frame Generation for Consistent Long Videos

Without incurring significant computational overhead, train-free long video generation aims to enable foundation video generation models to produce longer videos. Frame-level autoregressive frameworks, e.g., FIFO-diffusion, offer the advantage of generating infinitely long videos with constant memory consumption. However, the mismatch between training and inference, coupled with the challenge of maintaining long-term consistency, limits the effective utilization of foundation models. To mitigate these concerns, we propose \textbf{MIGA}, a novel infinite-frame long video generation method. Firstly, we propose an effective two-stage alignment mechanism that mitigates the training-inference gap by reducing the excessive noise span fed to the model. We then introduce an innovative dual consistency enhancement mechanism, where the self-reflection approach corrects early high-noise frames and the long-range frame guidance approach leverages later low-noise frames with broad coverage to steer generation, jointly improving temporal consistency. Extensive experiments on VBench and NarrLV demonstrate the state-of-the-art performance of MIGA. Our project page is available at https://xiaokunfeng.github.io/miga_homepage/.

preprint2021arXiv

Distinct magnetic ground states of $R_2$ZnIrO$_6$ ($R$ = La and Nd) determined by neutron powder diffraction

Double perovskite iridates $A_2$ZnIrO$_6$ ($A$ = alkaline or lanthanide) show complex magnetic behaviors ranging from weak ferromagnetism to successive antiferromagnetic transitions. Here we report the static ($dc$) and dynamic ($ac$) magnetic susceptibility, and neutron powder diffraction measurements for $A$ = La and Nd compounds to elucidate the magnetic ground state. Below 10~K, the $A$ = La compound is best described as canted iridium moments in an antiferromagnet arrangement with a propagation vector \textbf{k} = 0 and a net ferromagnetic component along the $c$-axis. On the other hand, Nd$_2$ZnIrO$_6$ is described well as an antiferromagnet with a propagation vector \textbf{k} = (1/2~1/2~0) below $T_\mathrm{N} \sim$ 17 K. Scattering from both the Nd and Ir magnetic sublattices were required to describe the data and both were found to lie almost completely within the $ab$-plane. $Dc$ susceptibility revealed a bifurcation between the zero-field-cooled and field-cooled curves below $\sim$13 K in Nd$_2$ZnIrO$_6$. A glassy state was ruled out by $ac$ susceptibility but detailed magnetic isotherms revealed the opening of the loop below 13~K. These results suggest a delicate balance exists between the Dzyaloshinskii-Moriya, crystal field schemes, and $d$-$f$ interaction in this series of compounds.

preprint2020arXiv

Measurement of two-particle correlations in hadronic $e^{+}e^{-}$ collisions at Belle

The enhancement of charged-particle pairs with large pseudorapidity difference and small azimuthal angle difference, often referred to as the ``ridge signal'', is a phenomenon widely observed in high multiplicity proton-proton, proton-ion and deutron-ion collisions, which is not yet fully understood. In heavy-ion collisions, the hydrodynamic expansion of the Quark-Gluon Plasma is one of the possible explanations of the origin of the ridge signal. Measurements in the $e^+e^-$ collision system, without the complexities introduced by hadron structure in the initial state, can serve as a complementary probe to examine the formation of a ridge signal. The first measurement of two-particle angular correlation functions in high multiplicity $e^+e^-$ collisions at $\sqrt{s}=10.52$ GeV is reported. The hadronic $e^+e^-$ annihilation data collected by the Belle detector at KEKB are used in this study. Two-particle angular correlation functions are measured over the full azimuth and large pseudorapidity intervals which are defined by either the electron beam axis or the event thrust as a function of charged particle multiplicity. The measurement in the event thrust analysis, with mostly outgoing quark pairs determining the reference axis, is sensitive to the region of additional soft gluon emissions. No significant ridge signal is observed with either coordinates analyses. Near side jet correlations appear to be absent in the thrust axis analysis. The measurements are compared to predictions from various event generators and expected to provide new constraints to the phenomenological models in the low energy regime.

preprint2020arXiv

Search for the Decay $B_s^0 \rightarrow η^\prime η$

In the Standard Model (SM) charmless hadronic decays $B_s^0 \rightarrow η^\prime η$ proceed via tree-level $b\to u$ and penguin $b\to s$ transitions. Penguin transitions are sensitive to Beyond-the-Standard-Model (BSM) physics scenarios and could affect the branching fractions and {\it CP} asymmetries in such decays. Once branching fractions for two-body decays $B_s \to ηη, ηη^{\prime}, η^{\prime}η^{\prime} $ are measured, and the theoretical uncertainties are reduced, it would be possible to extract {\it CP} violating parameters from the data using the formalism based on SU(3)/U(3) symmetry. To achieve this goal, at least four of these six branching fractions need to be measured. Only the branching fraction for $B_s^0 \to η^{\prime}η^{\prime}$ has been measured so far.

preprint2016arXiv

Angular analysis of $B^0 \to K^\ast(892)^0 \ell^+ \ell^-$

We present a measurement of angular observables, $P_4'$, $P_5'$, $P_6'$, $P_8'$, in the decay $B^0 \to K^\ast(892)^0 \ell^+ \ell^-$, where $\ell^+\ell^-$ is either $e^+e^-$ or $μ^+μ^-$. The analysis is performed on a data sample corresponding to an integrated luminosity of $711~\mathrm{fb}^{-1}$ containing $772\times 10^{6}$ $B\bar B$ pairs, collected at the $Υ(4S)$ resonance with the Belle detector at the asymmetric-energy $e^+e^-$ collider KEKB. Four angular observables, $P_{4,5,6,8}'$ are extracted in five bins of the invariant mass squared of the lepton system, $q^2$. We compare our results for $P_{4,5,6,8}'$ with Standard Model predictions including the $q^2$ region in which the LHCb collaboration reported the so-called $P_5'$ anomaly.

preprint2016arXiv

Direct determination of the spin structure of Nd$_2$Ir$_2$O$_7$ by means of neutron diffraction

We report on the spin structure of the pyrochlore iridate Nd$_2$Ir$_2$O$_7$ that could be directly determined by means of powder neutron diffraction. Our magnetic structure refinement unravels a so-called all-in/all-out magnetic structure that appears in both, the Nd and the Ir sublattice. The ordered magnetic moments at 1.8 K amount to 0.34(1) $μ_\mathrm{B}$/Ir$^{4+}$ and 1.27(1) $μ_\mathrm{B}$/Nd$^{3+}$. The Nd$^{3+}$ moment size at 1.8 K is smaller than that expected for the Nd$^{3+}$ ground state doublet. On the other hand, the size of the ordered moments of the Ir$^{4+}$ ions at 1.8 K agrees very well with the value expected for a $J_\mathrm{eff}$ = 1/2 state based on the presence of strong spin-orbit coupling in this system. Finally, our measurements reveal a parallel alignment of the Nd$^{3+}$ moments with the net moment of its six nearest neighboring Ir$^{4+}$ ions.

preprint2016arXiv

Evidence for the decay $B^{0}\to ηη$

We report a search for $B^{0}\to ηη$ with a data sample corresponding to an integrated luminosity of $698 \,{\rm fb}^{-1}$ containing $753 \times 10^{6}$ $B\bar{B}$ pairs collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. The branching fraction is measured to be $\mathcal{B}(B^{0} \to ηη) = (7.6^{+2.7 +1.4}_{-2.3 -1.6}) \times 10^{-7}$ at the level of 3.3 standard deviations above zero, which provides the first evidence for the decay $B^{0} \to ηη$.

preprint2016arXiv

Incommensurate spin correlations in highly oxidized cobaltates La$_{2-x}$Sr$_{x}$CoO$_{4}$

We observe quasi-static incommensurate magnetic peaks in neutron scattering experiments on layered cobalt oxides La2-xSrxCoO4 with high Co oxidation states that have been reported to be paramagnetic. This enables us to measure the magnetic excitations in this highly hole-doped incommensurate regime and compare our results with those found in the low-doped incommensurate regime that exhibit hourglass magnetic spectra. The hourglass shape of magnetic excitations completely disappears given a high Sr doping. Moreover, broad low-energy excitations are found, which are not centered at the incommensurate magnetic peak positions but around the quarter-integer values that are typically exhibited by excitations in the checkerboard charge ordered phase. Our findings suggest that the strong inter-site exchange interactions in the undoped islands are critical for the emergence of hourglass spectra in the incommensurate magnetic phases of La2-xSrxCoO4.

preprint2016arXiv

Measurement of $CP$ asymmetry in the $D^{0} \to K^0_S K^0_S$ decay at Belle

We report a measurement of the time-integrated $CP$ asymmetry in the neutral charm meson decay $D^0 \to K^0_S K^0_S$ using 921~fb$^{-1}$ data collected at the $Υ(4S)$ and $Υ(5S)$ resonances with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The observed asymmetry is $$ A_{CP}(D^0 \to K^0_S K^0_S) = (-0.02 \pm 1.53 \pm 0.17) \%, $$ where the first uncertainty is statistical and the second systematic. This latter uncertainty is dominated by the error of the normalisation channel. The result is consistent with Standard Model expectations and improves the uncertainty with respect to previous measurement of this quantity by more than a factor of three.

preprint2016arXiv

Measurement of Michel Parameters ($\barη$, $ξκ$) in the radiative leptonic decay of tau at Belle

We present the first measurement of the Michel parameters $\barη$ and $ξκ$ in the radiative leptonic decay of the $τ$ lepton using 703 f$\mathrm{b}^{-1}$ of data collected with the Belle detector at the KEKB $e^+e^-$ collider. The Michel parameters are measured by an unbinned maximum likelihood fit to the kinematic information of $e^+e^-\rightarrowτ^+τ^-\rightarrow (π^+π^0 \barν)(l^-ν\barνγ)$ $(l=e$ or $μ)$. The preliminary values of the measured Michel parameters are $\barη = -2.0 \pm 1.5 \pm 0.8$ and $ξκ= 0.6 \pm 0.4 \pm 0.2$, where the first error is statistical and the second is systematic.

preprint2016arXiv

Measurement of the $τ$ lepton polarization in the decay ${\bar B} \rightarrow D^* τ^- {\bar ν_τ}$

We report the first measurement of the $τ$ lepton polarization in the decay ${\bar B} \rightarrow D^* τ^- {\barν_τ}$ as well as a new measurement of the ratio of the branching fractions $R(D^{*}) = \mathcal{B}({\bar B} \rightarrow D^* τ^- {\barν_τ}) / \mathcal{B}({\bar B} \rightarrow D^* \ell^- {\barν_{\ell}})$, where $\ell^-$ denotes an electron or a muon, with the decays $τ^- \rightarrow π^- ν_τ$ and $τ^- \rightarrow ρ^- ν_τ$. We use the full data sample of $772 \times 10^6$ $B{\bar B}$ pairs accumulated with the Belle detector at the KEKB electron-positron collider. Our preliminary results, $R(D^*) = 0.276 \pm 0.034{\rm (stat.)} ^{+0.029} _{-0.026}{\rm (syst.)}$ and $P_τ = -0.44 \pm 0.47 {\rm (stat.)} ^{+0.20} _{-0.17} {\rm (syst.)}$, are consistent with the theoretical predictions of the Standard Model within $0.6$ standard deviation.

preprint2016arXiv

Measurement of the branching ratio of $\bar{B}^0 \rightarrow D^{*+} τ^- \barν_τ$ relative to $\bar{B}^0 \rightarrow D^{*+} \ell^- \barν_{\ell}$ decays with a semileptonic tagging method

We report a measurement of ratio ${\cal R}(D^*) = {\cal B}(\bar{B}^0 \rightarrow D^{*+} τ^- \barν_τ)/{\cal B}(\bar{B}^0 \rightarrow D^{*+} \ell^- \barν_{\ell})$, where $\ell$ denotes an electron or a muon. The results are based on a data sample containing $772\times10^6$ $B\bar{B}$ pairs recorded at the $Υ(4S)$ resonance with the Belle detector at the KEKB $e^+ e^-$ collider. We select a sample of $B^0 \bar{B}^0$ pairs by reconstructing both $B$ mesons in semileptonic decays to $D^{*\mp} \ell^{\pm}$. We measure ${\cal R}(D^*)= 0.302 \pm 0.030({\rm stat)} \pm 0.011({\rm syst)}$, which is within $1.6 σ$ of the Standard Model theoretical expectation, where $σ$ is the standard deviation including systematic uncertainties.

preprint2016arXiv

Observation of Transverse $Λ/\barΛ$ Hyperon Polarization in $e^+e^-$ Annihilation at Belle

We report the first observation of the polarization of $Λ/\barΛ$ hyperons transverse to its production plane in $e^+e^-$ annihilation. We observe a significant polarization that rises with the fractional energy carried by the hyperon as well as its transverse momentum. To define the production plane, we use the direction of the hyperon momentum together with either the thrust axis in the event or the momentum vector of a hadron in the opposite hemisphere. Furthermore, we investigate the contributions to the hyperon polarization from the feed-down from $Σ^0/\barΣ^0$ and $Λ_c^{\pm}$ decays. This measurement uses a dataset of 800.4fb$^{-1}$ collected by the Belle experiment at or near a center-of-mass energy of 10.58 GeV.

preprint2016arXiv

Study of Two-Body $e^+e^- \to B_s^{(*)}\bar{B}_s^{(*)}$ Production in the Energy Range from 10.77 to 11.02 GeV

We report results on the studies of the $e^+e^-\to B_s^{(*)}\bar{B}_s^{(*)}$ processes. The results are based on a $121.4$ fb$^{-1}$ data sample collected with the Belle detector at the center-of-mass energy near the $Υ(10860)$ peak and $16.4$ fb$^{-1}$ of data collected at 19 energy points in the range from 10.77 to 11.02 GeV. We observe a clear $e^+e^-\toΥ(10860)\to B_s^{(*)}\bar{B}_s^{(*)}$ signal, with no statistically significant signal of $e^+e^-\to Υ(11020)\to B_s^{(*)}\bar{B}_s^{(*)}$. The relative production ratio of $B_s^*\bar{B}_s^*$, $B_s\bar{B}_s^{*}$, and $B_s\bar{B}_s$ final states at $\sqrt{s}=10.866$ GeV is measured to be $7:$ $0.856\pm0.106(stat.)\pm0.053(syst.):$ $0.645\pm0.094(stat.)^{+0.030}_{-0.033}(syst.)$. An angular analysis of the $B_s^*\bar{B}_s^*$ final state produced at the $Υ(10860)$ peak is also performed.

preprint2016arXiv

Study of χ_{bJ}(1P) Properties in the Radiative Υ(2S) Decays

We report a study of radiative decays of χ_{bJ}(1P)(J=0,1,2) mesons into 74 hadronic final states comprising charged and neutral pions, kaons, protons; out of these, 41 modes are observed with at least 5 standard deviation significance. Our measurements not only improve the previous measurements by the CLEO Collaboration but also lead to first observations in many new modes. The large sample allows us to probe the total decay width of the χ_{b0}(1P). In the absence of a statistically significant result, a 90% confidence-level upper limit is set on the width at Γ_{total}< 2.4 MeV. Our results are based on 24.7 fb^{-1} of e+e- collision data recorded by the Belle detector at the Υ(2S) resonance, corresponding to (157.8\pm3.6)\times10^6 Υ(2S) decays.

preprint2015arXiv

High sensitivity microwave detection using a magnetic tunnel junction in the absence of an external applied magnetic field

In the absence of any external applied magnetic field, we have found that a magnetic tunnel junction (MTJ) can produce a significant output direct voltage under microwave radiation at frequencies, which are far from the ferromagnetic resonance condition, and this voltage signal can be increase by at least an order of magnitude by applying a direct current bias. The enhancement of the microwave detection can be explained by the nonlinear resistance/conductance of the MTJs. Our estimation suggests that optimized MTJs should achieve sensitivities for non-resonant broadband microwave detection of about 5,000 mV/mW.

preprint2015arXiv

Measurement of Azimuthal Modulations in the Cross-Section of Di-Pion Pairs in Di-Jet Production from Electron-Positron Annihilation

We present an extraction of azimuthal correlations between two pairs of charged pions detected in opposite jets from electron-positron annihilation. These correlations may arise from the dependence of the di-pion fragmentation on the polarization of the parent quark in the process $e^+e^- \rightarrow q \bar{q}$. Due to the correlation of the quark polarizations, the cross-section of di-pion pair production, in which the pion pairs are detected in opposite jets in a dijet event, exhibits a modulation in the azimuthal angles of the planes containing the hadron pairs with respect to the production plane. The measurement of this modulation allows access to combinations of fragmentation functions that are sensitive to the quark's transverse polarization and helicity. Within our uncertainties we do not observe a significant signal from the previously unmeasured helicity dependent fragmentation function $G_1^\perp$. This measurement uses a dataset of 938~fb$^{-1}$ collected by the Belle experiment at or near $\sqrt{s}\approx10.58$ GeV.

preprint2015arXiv

Measurement of the amplitude ratio of $B^0 \to D^0K^{*0}$ and $B^0 \to \bar{D^0}K^{*0}$ decays with a model-independent Dalitz plot analysis using $D\to K_S^0π^+π^-$ decays

We report a measurement of the amplitude ratio $r_S$ of $B^0 \to D^0K^{*0}$ and $B^0 \to \bar{D^0}K^{*0}$ decays with a model-independent Dalitz plot analysis using $D\to K_S^0π^+π^-$ decays. Using the full data sample of $772\times10^6$ $B\bar{B}$ pairs collected at the $Υ(4S)$ resonance with the Belle detector at KEKB accelerator the upper limit is $r_S < 0.87$ at the 68 % confidence level. This result is the first measurement of $r_S$ with a model-independent Dalitz analysis, and is consistent with results from other analyses. The value of $r_S$ indicates the sensitivity of the decay to $ϕ_3$ because the statistical uncertainty is proportional to $1/r_S$. The $r_S$ result is obtained from observables ($x_\pm$, $y_\pm$) \begin{eqnarray} x_- &=& +0.4 ^{+1.0 +0.0}_{-0.6 -0.1} \pm0.0 \\ y_- &=& -0.6 ^{+0.8 +0.1}_{-1.0 -0.0} \pm0.1 \\ x_+ &=& +0.1 ^{+0.7 +0.0}_{-0.4 -0.1} \pm0.1 \\ y_+ &=& +0.3 ^{+0.5 +0.0}_{-0.8 -0.1} \pm0.1 \\ , \end{eqnarray} where $x_\pm = r_S \cos(δ_S \pm ϕ_3)$, $y_\pm = r_S \sin(δ_S \pm ϕ_3)$ and $ϕ_3 (δ_S)$ are the weak (strong) phase difference between $B^0 \to D^0K^{*0}$ and $B^0 \to \bar{D^0}K^{*0}$. The first uncertainty is statistical, the second is the experimental systematic and the third is the systematic due to the uncertainties on $c_i$ and $s_i$ parameters measured by CLEO.

preprint2015arXiv

Nature of Intra-night Optical Variability of BL Lacertae

We present the results of extensive multi-band intra-night optical monitoring of BL Lacertae during 2010--2012. BL Lacertae was very active in this period and showed intense variability in almost all wavelengths. We extensively observed it for a total for 38 nights; on 26 of them observations were done quasi-simultaneously in B, V, R and I bands (totaling 113 light curves), with an average sampling interval of around 8 minutes. BL Lacertae showed significant variations on hour-like timescales in a total of 19 nights in different optical bands. We did not find any evidence for periodicities or characteristic variability time-scales in the light curves. The intranight variability amplitude is generally greater at higher frequencies and decreases as the source flux increases. We found spectral variations in BL Lacertae in the sense that the optical spectrum becomes flatter as the flux increases but in several flaring states deviates from the linear trend suggesting different jet components contributing to the emission at different times.

preprint2015arXiv

Theory and experiment on cavity magnon polariton in the 1D configuration

We have theoretically and experimentally investigated the dispersion of the cavity-magnon-polariton (CMP) in a 1D configuration, created by inserting a low damping magnetic insulator into a high-quality 1D microwave cavity. By simplifying the full-wave simulation based on the transfer matrix approach in the long wavelength limit, an analytic approximation of the CMP dispersion has been obtained. The resultant coupling strength of the CMP shows different dependence on the sample thickness as well as the permittivity of the sample, determined by the parity of the cavity modes. These scaling effects of the cavity and material parameters are confirmed by experimental data. Our work provide a detailed understanding of the 1D CMP, which could help to engineer coupled magnon-photon system.

preprint2014arXiv

Accessing defect dynamics using intense, nanosecond pulsed ion beams

Gaining in-situ access to relaxation dynamics of radiation induced defects will lead to a better understanding of materials and is important for the verification of theoretical models and simulations. We show preliminary results from experiments at the new Neutralized Drift Compression Experiment (NDCX-II) at Lawrence Berkeley National Laboratory that will enable in-situ access to defect dynamics through pump-probe experiments. Here, the unique capabilities of the NDCX-II accelerator to generate intense, nanosecond pulsed ion beams are utilized. Preliminary data of channeling experiments using lithium and potassium ions and silicon membranes are shown. We compare these data to simulation results using Crystal Trim. Furthermore, we discuss the improvements to the accelerator to higher performance levels and the new diagnostics tools that are being incorporated.

preprint2014arXiv

Measurement of the branching fraction of $B^+ \to τ^+ ν_τ$ decays with the semileptonic tagging method and the full Belle data sample

We report a measurement of the branching fraction of $B^+ \to τ^+ ν_τ$ decays using a data sample of $772 \times 10^6 B \bar{B}$ pairs, collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We reconstruct the accompanying $B$ meson in a semileptonic decay and detect the $B^+ \to τ^+ ν_τ$ candidate in the recoiling event. We obtain a branching fraction of ${\cal B}(B^+ \to τ^+ ν_τ) = [1.25 \pm 0.28 ({\rm stat.}) \pm 0.27({\rm syst.})] \times 10^{-4}$. This result is in good agreement with previous measurements and the expectation from calculations based on the Standard Model.

preprint2014arXiv

Strain driven anisotropic magnetoresistance in antiferromagnetic La$_{0.4}$Sr$_{0.6}$MnO$_{3}$

We investigate the effects of strain on antiferromagntic (AFM) single crystal thin films of La$_{1-x}$Sr$_{x}$MnO$_{3}$ (x = 0.6). Nominally unstrained samples have strong magnetoresistance with anisotropic magnetoresistances (AMR) of up to 8%. Compressive strain suppresses magnetoresistance but generates AMR values of up to 63%. Tensile strain presents the only case of a metal-insulator transition and demonstrates a previously unreported AMR behavior. In all three cases, we find evidence of magnetic ordering and no indication of a global ferromagnetic phase transition. These behaviors are attributed to epitaxy induced changes in orbital occupation driving different magnetic ordering types. Our findings suggest that different AFM ordering types have a profound impact on the AMR magnitude and character.

preprint2013arXiv

Adsorption of PTCDA and C60 on KBr(001): electrostatic interaction versus electronic hybridization

The adsorption of functional molecules on insulator surfaces is of great importance to molecular electronics. We present a systematical investigation of geometric and electronic properties of PTCDA and C60 on KBr(001) using DFT and non-contact atomic force microscopy. It was found that electrostatics is the primary interaction mechanism for PTCDA and C60 adsorbed on KBr. It was thus concluded that alkali-halides is a competitive candidate to be adopted to support low polarizability molecules, such as PTCDA, in future electronics.

preprint2013arXiv

Generating mid-IR octave-spanning supercontinua and few-cycle pulses with solitons in phase-mismatched quadratic nonlinear crystals

We discuss a novel method for generating octave-spanning supercontinua and few-cycle pulses in the important mid-IR wavelength range. The technique relies on strongly phase-mismatched cascaded second-harmonic generation (SHG) in mid-IR nonlinear frequency conversion crystals. Importantly we here investigate the so-called noncritical SHG case, where no phase matching can be achieved but as a compensation the largest quadratic nonlinearities are exploited. A self-defocusing temporal soliton can be excited if the cascading nonlinearity is larger than the competing material self-focusing nonlinearity, and we define a suitable figure of merit to screen a wide range of mid-IR dielectric and semiconductor materials with large effective second-order nonlinearities $d_{\rm eff}$. The best candidates have simultaneously a large bandgap and a large $d_{\rm eff}$. We show selected realistic numerical examples using one of the promising crystals: in one case soliton pulse compression from 50 fs to 15 fs (1.5 cycles) at $3.0\mic$ is achieved, and at the same time a 3-cycle dispersive wave at $5.0\mic$ is formed that can be isolated using a long-pass filter. In another example we show that extremely broadband supercontinua can form spanning the near-IR to the end of the mid-IR (nearly 4 octaves).

preprint2012arXiv

Study of Three-Body Y(10860) Decays

We report preliminary results on the analysis of the three-body Y(10860)=> B barB pi, Y(10860) => (B barB* + c.c.) pi and Y(10860)=> B* barB* pi decays including an observation of the Y(10860)=> Zb(10610)+- pi-+ => [B barB*+c.c]+- pi-+ and Y(10860)=> Zb(10650)+- pi-+ => [B* barB*]+- pi-+ decays as intermediate channels. We measure branching fractions of the three-body decays to be Br(Y(10860)=> [B barB*+c.c.]+- pi-+)=(28.3+-2.9+-4.6)x10^{-3} and Br(Y(10860)=> [B* barB*]+- pi-+)=(14.1+-1.9+-2.4)x10^{-3} and set 90% C.L. upper limit Br(Y(10860)=> [B barB]+- pi-+)<4.0x10^{-3}. We also report results on the amplitude analysis of the three-body Y(10860)=>Y(nS)pi+pi-, n=1,2,3 decays and the analysis of the internal structure of the three-body Y(10860)=>hb(mP)pi+pi-, m=1,2 decays. The results are based on a 121.4 1/fb data sample collected with the Belle detector at a center-of-mass energy near the Y(10860).

preprint2010arXiv

Belle II Technical Design Report

The Belle detector at the KEKB electron-positron collider has collected almost 1 billion Y(4S) events in its decade of operation. Super-KEKB, an upgrade of KEKB is under construction, to increase the luminosity by two orders of magnitude during a three-year shutdown, with an ultimate goal of 8E35 /cm^2 /s luminosity. To exploit the increased luminosity, an upgrade of the Belle detector has been proposed. A new international collaboration Belle-II, is being formed. The Technical Design Report presents physics motivation, basic methods of the accelerator upgrade, as well as key improvements of the detector.

preprint2010arXiv

Microscopic Approach to Shear Viscosities in Superfluid Gases: From BCS to BEC

We compute the shear viscosity, $η$, at general temperatures $T$, in a BCS-BEC crossover scheme which is demonstrably consistent with conservation laws. The study of $η$ is important because it constrains microscopic theories by revealing the excitation spectra. The onset of a normal state pairing gap and the contribution from pair degrees of freedom imply that $η$ at low $T$ becomes small, rather than exhibiting the upturn predicted by most others. Using the local density approximation, we find quite reasonable agreement with just-published experiments.