785 research outputs found

    MReD: A Meta-Review Dataset for Structure-Controllable Text Generation

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    When directly using existing text generation datasets for controllable generation, we are facing the problem of not having the domain knowledge and thus the aspects that could be controlled are limited. A typical example is when using CNN/Daily Mail dataset for controllable text summarization, there is no guided information on the emphasis of summary sentences. A more useful text generator should leverage both the input text and the control signal to guide the generation, which can only be built with a deep understanding of the domain knowledge. Motivated by this vision, our paper introduces a new text generation dataset, named MReD. Our new dataset consists of 7,089 meta-reviews and all its 45k meta-review sentences are manually annotated with one of the 9 carefully defined categories, including abstract, strength, decision, etc. We present experimental results on start-of-the-art summarization models, and propose methods for structure-controlled generation with both extractive and abstractive models using our annotated data. By exploring various settings and analyzing the model behavior with respect to the control signal, we demonstrate the challenges of our proposed task and the values of our dataset MReD. Meanwhile, MReD also allows us to have a better understanding of the meta-review domain.Comment: 15 pages, 5 figures, accepted at ACL 202

    Realigned Hardy's Paradox

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    Hardy's paradox provides an all-versus-nothing fashion to directly certify that quantum mechanics cannot be completely described by local realistic theory. However, when considering potential imperfections in experiments, like imperfect entanglement source and low detection efficiency, the original Hardy's paradox may induce a rather small Hardy violation and only be realized by expensive quantum systems. To overcome this problem, we propose a realigned Hardy's paradox. Compared with the original version of Hardy's paradox, the realigned Hardy's paradox can dramatically improve the Hardy violation. Then, we generalize the realigned Hardy's paradox to arbitrary even nn dichotomic measurements. For n=2n=2 and n=4n=4 cases, the realigned Hardy's paradox can achieve Hardy values P(00∣A1B1)P(00|A_1B_1) approximate 0.41400.4140 and 0.77340.7734 respectively compared with 0.090.09 of the original Hardy's paradox. Meanwhile, the structure of the realigned Hardy's paradox is simpler and more robust in the sense that there is only one Hardy condition rather than three conditions. One can anticipate that the realigned Hardy's paradox can tolerate more experimental imperfections and stimulate more fascinating quantum information applications.Comment: 7 pages, 1 figur

    Update of ∣Vcb∣|V_{cb}| from the Bˉ→D∗ℓνˉ\bar{B}\to D^*\ell\bar{\nu} form factor at zero recoil with three-flavor lattice QCD

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    We compute the zero-recoil form factor for the semileptonic decay Bˉ0→D∗+ℓ−νˉ\bar{B}^0\to D^{*+}\ell^-\bar{\nu} (and modes related by isospin and charge conjugation) using lattice QCD with three flavors of sea quarks. We use an improved staggered action for the light valence and sea quarks (the MILC \asqtad\ configurations), and the Fermilab action for the heavy quarks. Our calculations incorporate higher statistics, finer lattice spacings, and lighter quark masses than our 2008 work. As a byproduct of tuning the new data set, we obtain the DsD_s and BsB_s hyperfine splittings with few-MeV accuracy. For the zero-recoil form factor, we obtain F(1)=0.906(4)(12)\mathcal{F}(1)=0.906(4)(12), where the first error is statistical and the second is the sum in quadrature of all systematic errors. With the latest HFAG average of experimental results and a cautious treatment of QED effects, we find ∣Vcb∣=(39.04±0.49expt±0.53QCD±0.19QED)×10−3|V_{cb}| = (39.04 \pm 0.49_\text{expt} \pm 0.53_\text{QCD} \pm 0.19_\text{QED})\times10^{-3}. The QCD error is now commensurate with the experimental error.Comment: 53 pages, 12 figures; expanded discussion of correlator fits, typos corrected, conforms to version published in PR

    B→πℓℓB\to\pi\ell\ell form factors for new-physics searches from lattice QCD

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    The rare decay B→πℓ+ℓ−B\to\pi\ell^+\ell^- arises from b→db\to d flavor-changing neutral currents and could be sensitive to physics beyond the Standard Model. Here, we present the first abab-initioinitio QCD calculation of the B→πB\to\pi tensor form factor fTf_T. Together with the vector and scalar form factors f+f_+ and f0f_0 from our companion work [J. A. Bailey et al.et~al., Phys. Rev. D 92, 014024 (2015)], these parameterize the hadronic contribution to B→πB\to\pi semileptonic decays in any extension of the Standard Model. We obtain the total branching ratio BR(B+→π+μ+μ−)=20.4(2.1)×10−9{\text{BR}}(B^+\to\pi^+\mu^+\mu^-)=20.4(2.1)\times10^{-9} in the Standard Model, which is the most precise theoretical determination to date, and agrees with the recent measurement from the LHCb experiment [R. Aaij et al.et~al., JHEP 1212, 125 (2012)]. Note added: after this paper was submitted for publication, LHCb announced a new measurement of the differential decay rate for this process [T. Tekampe, talk at DPF 2015], which we now compare to the shape and normalization of the Standard-Model prediction.Comment: V3: Corrected errors in results for Standard-Model differential and total decay rates in abstract, Fig. 3, Table IV, and outlook. Added new preliminary LHCb data to Fig. 3 and brief discussion after outlook. Replaced outdated correlation matrix in Table III with correct final version. Other minor wording changes and references added. 7 pages, 4 tables, 3 figure

    B→Kl+l−B\to Kl^+l^- decay form factors from three-flavor lattice QCD

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    We compute the form factors for the B→Kl+l−B \to Kl^+l^- semileptonic decay process in lattice QCD using gauge-field ensembles with 2+1 flavors of sea quark, generated by the MILC Collaboration. The ensembles span lattice spacings from 0.12 to 0.045 fm and have multiple sea-quark masses to help control the chiral extrapolation. The asqtad improved staggered action is used for the light valence and sea quarks, and the clover action with the Fermilab interpretation is used for the heavy bb quark. We present results for the form factors f+(q2)f_+(q^2), f0(q2)f_0(q^2), and fT(q2)f_T(q^2), where q2q^2 is the momentum transfer, together with a comprehensive examination of systematic errors. Lattice QCD determines the form factors for a limited range of q2q^2, and we use the model-independent zz expansion to cover the whole kinematically allowed range. We present our final form-factor results as coefficients of the zz expansion and the correlations between them, where the errors on the coefficients include statistical and all systematic uncertainties. We use this complete description of the form factors to test QCD predictions of the form factors at high and low q2q^2. We also compare a Standard-Model calculation of the branching ratio for B→Kl+l−B \to Kl^+l^- with experimental data.Comment: V2: Fig.7 added. Typos text corrected. Reference added. Version published in Phys. Rev.

    Refining new-physics searches in B -> D tau nu decay with lattice QCD

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    The semileptonic decay channel B -> D tau nu is sensitive to the presence of a scalar current, such as that mediated by a charged-Higgs boson. Recently the BaBar experiment reported the first observation of the exclusive semileptonic decay B -> D tau nu, finding an approximately 2-sigma disagreement with the Standard-Model prediction for the ratio R(D)=BR(B->D tau nu)/BR(B->D l nu), where l=e,mu. We compute this ratio of branching fractions using hadronic form factors computed in unquenched lattice QCD and obtain R(D) = 0.316(12)(7), where the errors are statistical and total systematic, respectively. This result is the first Standard-Model calculation of R(D) from ab initio full QCD. Its error is smaller than that of previous estimates, primarily due to the reduced uncertainty in the scalar form factor f_0(q^2). Our determination of R(D) is approximately 1-sigma higher than previous estimates and, thus, reduces the tension with experiment. We also compute R(D) in models with electrically charged scalar exchange, such as the type II two-Higgs doublet model. Once again, our result is consistent with, but approximately 1-sigma higher than, previous estimates for phenomenologically relevant values of the scalar coupling in the type II model. As a byproduct of our calculation, we also present the Standard-Model prediction for the longitudinal polarization ratio P_L (D)= 0.325(4)(3).Comment: 6 pages, 3 figures, 1 table. References and text added. Fig. 3 R(D) in 2HDM II corrected and conclusions modified. Standard-Model R(D) unchange

    B_s->D_s/B->D Semileptonic Form-Factor Ratios and Their Application to BR(B^0_s->\mu^+\mu^-)

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    We calculate form-factor ratios between the semileptonic decays \bar{B}->D^+\ell^-\bar{\nu} and \bar{B}_s->D_s^+\ell^-\bar{\nu} with lattice QCD. These ratios are a key theoretical input in a new strategy to determine the fragmentation fractions of the neutral B decays, which are needed for measurements of BR(B^0_s-> \mu^+\mu^-). We use the MILC ensembles of gauge configurations with 2+1 flavors of sea quarks at two lattice spacings of approximately 0.12 fm and 0.09 fm. We use the model-independent z-parametrization to extrapolate our simulation results at small recoil toward maximum recoil. Our results for the form-factor ratios are f0(s)(MÏ€2)/f0(d)(MK2)=1.046(44)stat.(15)syst.f_0^{(s)}(M^2_\pi)/f_0^{(d)}(M^2_K) =1.046(44)_{stat.}(15)_{syst.} and f0(s)(MÏ€2)/f0(d)(MÏ€2)=1.054(47)stat.(17)syst.f_0^{(s)}(M^2_\pi)/f_0^{(d)}(M^2_\pi)=1.054(47)_{stat.}(17)_{syst.}. In contrast to a QCD sum-rule calculation, no significant departure from U-spin (ds) symmetry is observed.Comment: 30 pages, 11 figures. Fig. 1 updated. Table II added. Conforms with version published in Physical Review D, except typos fixed, as in the PRD Erratum, in Table V (previously Table IV in arXiv v1). Results unchange
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