662 research outputs found

    Spin dynamics of a trapped spin-1 Bose Gas above the Bose-Einstein transition temperature

    Full text link
    We study collective spin oscillations in a spin-1 Bose gas above the Bose-Einstein transition temperature. Starting from the Heisenberg equation of motion, we derive a kinetic equation describing the dynamics of a thermal gas with the spin-1 degree of freedom. Applying the moment method to the kinetic equation, we study spin-wave collective modes with dipole symmetry. The dipole modes in the spin-1 system are found to be classified into the three type of modes. The frequency and damping rate are obtained as functions of the peak density. The damping rate is characterized by three relaxation times associated with collisions.Comment: 19 pages, 5 figur

    Charmless Exclusive Baryonic B Decays

    Full text link
    We present a systematical study of two-body and three-body charmless baryonic B decays. Branching ratios for two-body modes are in general very small, typically less than 10−610^{-6}, except that \B(B^-\to p \bar\Delta^{--})\sim 1\times 10^{-6}. In general, Bˉ→NΔˉ>Bˉ→NNˉ\bar B\to N\bar\Delta>\bar B\to N\bar N due to the large coupling constant for Σb→BΔ\Sigma_b\to B\Delta. For three-body modes we focus on octet baryon final states. The leading three-dominated modes are Bˉ0→pnˉπ−(ρ−),npˉπ+(ρ+)\bar B^0\to p\bar n\pi^-(\rho^-), n\bar p\pi^+(\rho^+) with a branching ratio of order 3×10−63\times 10^{-6} for Bˉ0→pnˉπ−\bar B^0\to p\bar n\pi^- and 8×10−68\times 10^{-6} for Bˉ0→pnˉρ−\bar B^0\to p\bar n\rho^-. The penguin-dominated decays with strangeness in the meson, e.g., B−→ppˉK−(∗)B^-\to p\bar p K^{-(*)} and Bˉ0→pnˉK−(∗),nnˉKˉ0(∗)\bar B^0\to p\bar n K^{-(*)}, n\bar n \bar K^{0(*)}, have appreciable rates and the NNˉN\bar N mass spectrum peaks at low mass. The penguin-dominated modes containing a strange baryon, e.g., Bˉ0→Σ0pˉπ+,Σ−nˉπ+\bar B^0\to \Sigma^0\bar p\pi^+, \Sigma^-\bar n\pi^+, have branching ratios of order (1∼4)×10−6(1\sim 4)\times 10^{-6}. In contrast, the decay rate of Bˉ0→Λpˉπ+\bar B^0\to\Lambda\bar p\pi^+ is smaller. We explain why some of charmless three-body final states in which baryon-antibaryon pair production is accompanied by a meson have a larger rate than their two-body counterparts: either the pole diagrams for the former have an anti-triplet bottom baryon intermediate state, which has a large coupling to the BB meson and the nucleon, or they are dominated by the factorizable external WW-emission process.Comment: 46 pages and 3 figures, to appear in Phys. Rev. D. Major changes are: (i) Calculations of two-body baryonic B decays involving a Delta resonance are modified, and (ii) Penguin-dominated modes B-> Sigma+N(bar)+p are discusse

    Sudden switch of generalized Lieb-Robinson velocity in a transverse field Ising spin chain

    Full text link
    The Lieb-Robinson theorem states that the speed at which the correlations between two distant nodes in a spin network can be built through local interactions has an upper bound, which is called the Lieb-Robinson velocity. Our central aim is to demonstrate how to observe the Lieb-Robinson velocity in an Ising spin chain with a strong transverse field. We adopt and compare four correlation measures for characterizing different types of correlations, which include correlation function, mutual information, quantum discord, and entanglement of formation. We prove that one of correlation functions shows a special behavior depending on the parity of the spin number. All the information-theoretical correlation measures demonstrate the existence of the Lieb-Robinson velocity. In particular, we find that there is a sudden switch of the Lieb-Robinson speed with the increasing of the number of spin

    Nonfactorizable contributions to B→D(∗)MB \to D^{(*)} M decays

    Full text link
    While the factorization assumption works well for many two-body nonleptonic BB meson decay modes, the recent measurement of Bˉ→D(∗)0M0\bar B\to D^{(*)0}M^0 with M=πM=\pi, ρ\rho and ω\omega shows large deviation from this assumption. We analyze the B→D(∗)MB\to D^{(*)}M decays in the perturbative QCD approach based on kTk_T factorization theorem, in which both factorizable and nonfactorizable contributions can be calculated in the same framework. Our predictions for the Bauer-Stech-Wirbel parameters, ∣a2/a1∣=0.43±0.04|a_2/a_1|= 0.43\pm 0.04 and Arg(a2/a1)∼−42∘Arg(a_2/a_1)\sim -42^\circ and ∣a2/a1∣=0.47±0.05|a_2/a_1|= 0.47\pm 0.05 and Arg(a2/a1)∼−41∘Arg(a_2/a_1)\sim -41^\circ, are consistent with the observed B→DπB\to D\pi and B→D∗πB\to D^*\pi branching ratios, respectively. It is found that the large magnitude ∣a2∣|a_2| and the large relative phase between a2a_2 and a1a_1 come from color-suppressed nonfactorizable amplitudes. Our predictions for the Bˉ0→D(∗)0ρ0{\bar B}^0\to D^{(*)0}\rho^0, D(∗)0ωD^{(*)0}\omega branching ratios can be confronted with future experimental data.Comment: 25 pages with Latex, axodraw.sty, 6 figures and 5 tables, Version published in PRD, Added new section 5 and reference

    Search for Charmless Two-body Baryonic Decays of B Mesons

    Get PDF
    We report the results of a search for the rare baryonic decays B0→ppˉB^0 \to p\bar{p}, ΛΛˉ\Lambda\bar{\Lambda}, and B+→pΛˉB^+ \to p\bar{\Lambda}. The analysis is based on a data set of 31.7×106BBˉ31.7\times 10^6 B\bar{B} events collected by the Belle detector at the KEKB e+e−e^+e^- collider. No statistically significant signals are found, and we set branching fraction upper limits B(B0→ppˉ)<1.2×10−6{\mathcal B}(B^0 \to p\bar{p}) < 1.2 \times 10^{-6}, B(B0→ΛΛˉ)<1.0×10−6{\mathcal B}(B^0 \to \Lambda\bar{\Lambda}) < 1.0 \times 10^{-6}, and B(B+→pΛˉ)<2.2×10−6{\mathcal B}(B^+ \to p\bar{\Lambda}) < 2.2 \times 10^{-6} at the 90% confidence level.Comment: 6 pages, 4 figures and 1 table. Submitted to Phys. Rev. D Rapid Communication

    Influence of Bleeding Risk on Outcomes of Radial and Femoral Access for Percutaneous Coronary Intervention: An Analysis From the GLOBAL LEADERS Trial

    Get PDF
    Background: Radial artery access has been shown to reduce mortality and bleeding events, especially in patients with acute coronary syndromes. Despite this, interventional cardiologists experienced in femoral artery access still prefer that route for percutaneous coronary intervention. Little is known regarding the merits of each vascular access in patients stratified by their risk of bleeding. Methods: Patients from the Global Leaders trial were dichotomized into low or high risk of bleeding by the median of the PRECISE-DAPT score. Clinical outcomes were compared at 30 days. Results: In the overall population, there were no statistical differences between radial and femoral access in the rate of the primary end point, a composite of all-cause mortality, or new Q-wave myocardial infarction (MI) (hazard ratio [HR] 0.70, 95% confidence interval [CI] 0.42-1.15). Radial access was associated with a significantly lower rate of the secondary safety end point, Bleeding Academic Research Consortium (BARC) 3 or 5 bleeding (HR 0.55, 95% CI 0.36-0.84). Compared by bleeding risk strata, in the high bleeding score population, the primary (HR 0.47, 95% CI 0.26-0.85; P = 0.012; Pinteraction = 0.019) and secondary safety (HR 0.57, 95% CI 0.35-0.95; P = 0.030; Pinteraction = 0.631) end points favoured radial access. In the low bleeding score population, however, the differences in the primary and secondary safety end points between radial and femoral artery access were no longer statistically significant. Conclusions: Our findings suggest that the outcomes of mortality or new Q-wave MI and BARC 3 or 5 bleeding favour radial access in patients with a high, but not those with a low, risk of bleeding. Because thisContexte : Il a et e d emontr e que l ’accès par l’artère radiale reduit la mortalite et les h emorragies, en particulier chez les patients presentant un syndrome coronarien aigu. Malgr e cela, les cardiologues interventionnels qui ont acquis de l’experience en matière d ’accès par l’artère femorale pr efèrent encore utiliser cette voie lorsqu ’ils doivent pratiquer une intervention coronarienne percutanee. On connaît mal l’interêt de chacune de ces techniques d ’accès vasculaire au regard du risque d’hemorragie. Methodologie : Les patients de l’essai GLOBAL LEADERS ont et e repartis en deux groupes, selon qu ’ils presentaient un risque d’hemorragie faible ou elev e d ’après le score PRECISE-DAPT median, puis les resultats cliniques ont et e compar es à 30 jours. Resultats : Dans l’ensemble de la population, aucune difference sta- tistiquement significative n’a et e observ ee entre l ’accès radial et l’accès femoral quant au critère d ’evaluation principal, compos e de la mortalite toutes causes confondues et d ’un nouvel infarctus du myocarde (IM) avec onde Q (rapport des risques instantanes [RRI] de 0,70; intervalle de confiance [IC] à 95 % : 0,42-1,15). L’accès radial a et e associe à un taux signi ficativement plus faible de survenue du critère secondaire d’evaluation de l ’innocuite, c ’est-à-dire une hemorragie de type 3 ou 5 selon la classification du BARC (Bleeding Academic Research Consortium) (RRI de 0,55; IC à 95 % : 0,36-0,84). Lorsqu’on compare les sujets en fonction du risque d’hemorragie, les critères d’evaluation de l ’innocuite principal (RRI de 0,47; IC à 95 % : 0,26- 0,85; p ¼ 0,012; pinteraction ¼ 0,019) et secondaire (RRI de 0,57; IC à 95 % : 0,35-0,95; p ¼ 0,030; pinteraction ¼ 0,631) sont favorables à l’accès radial au sein de la population presentant un risque d ’hemor- ragie elev e. Dans la population pr esentant un risque d ’hemorragie faible, les differences entre l ’accès radial et l’accès femoral quant aux critères d’evaluation de l ’innocuite principal et secondaire ne sont toutefois plus statistiquement significatives. Conclusions : Selon ces observations, les resultats concernant la mortalite ou la survenue d ’un nouvel IM avec onde Q et le risque d’hemorragie de type 3 ou 5 selon la classi fication du BARC indiquent que l’accès radial serait à privilegier lorsque le risque d ’hemorragie est elev e, mais pas lorsqu ’il est faible. Comme il ne s’agissait pas d’une analyse principale, il convient de considerer ces observations comme etant g en eratrices d ’hypothèses

    Short Distance vs. Long Distance Physics: The Classical Limit of the Minimal Length Uncertainty Relation

    Get PDF
    We continue our investigation of the phenomenological implications of the "deformed" commutation relations [x_i,p_j]=i hbar[(1 + beta p^2) delta_{ij} + beta' p_i p_j]. These commutation relations are motivated by the fact that they lead to the minimal length uncertainty relation which appears in perturbative string theory. In this paper, we consider the effects of the deformation on the classical orbits of particles in a central force potential. Comparison with observation places severe constraints on the value of the minimum length.Comment: 20 pages REVTEX4, 4 color eps figures, typos correcte

    At the edge of intonation: the interplay of utterance-final F0 movements and voiceless fricative sounds

    Get PDF
    The paper is concerned with the 'edge of intonation' in a twofold sense. It focuses on utterance-final F0 movements and crosses the traditional segment-prosody divide by investigating the interplay of F0 and voiceless fricatives in speech production. An experiment was performed for German with four types of voiceless fricatives: /f/, /s/, /ʃ/ and /x/. They were elicited with scripted dialogues in the contexts of terminal falling statement and high rising question intonations. Acoustic analyses show that fricatives concluding the high rising question intonations had higher mean centres of gravity (CoGs), larger CoG ranges and higher noise energy levels than fricatives concluding the terminal falling statement intonations. The different spectral-energy patterns are suitable to induce percepts of a high 'aperiodic pitch' at the end of the questions and of a low 'aperiodic pitch' at the end of the statements. The results are discussed with regard to the possible existence of 'segmental intonation' and its implication for F0 truncation and the segment-prosody dichotomy, in which segments are the alleged troublemakers for the production and perception of intonation

    An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics

    Get PDF
    For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types

    Single Spin Asymmetry ANA_N in Polarized Proton-Proton Elastic Scattering at s=200\sqrt{s}=200 GeV

    Get PDF
    We report a high precision measurement of the transverse single spin asymmetry ANA_N at the center of mass energy s=200\sqrt{s}=200 GeV in elastic proton-proton scattering by the STAR experiment at RHIC. The ANA_N was measured in the four-momentum transfer squared tt range 0.003⊽∣t∣⊽0.0350.003 \leqslant |t| \leqslant 0.035 \GeVcSq, the region of a significant interference between the electromagnetic and hadronic scattering amplitudes. The measured values of ANA_N and its tt-dependence are consistent with a vanishing hadronic spin-flip amplitude, thus providing strong constraints on the ratio of the single spin-flip to the non-flip amplitudes. Since the hadronic amplitude is dominated by the Pomeron amplitude at this s\sqrt{s}, we conclude that this measurement addresses the question about the presence of a hadronic spin flip due to the Pomeron exchange in polarized proton-proton elastic scattering.Comment: 12 pages, 6 figure
    • …
    corecore