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We accomplish for the first time the next-to-leading-order QCD computations of the leading-twist contributions to the Dirac form factors of both the proton and the neutron by applying the hard-collinear factorization theorem rigorously. The resulting predictions for these baryon form factors indicate that the one-loop perturbative corrections to the hard-gluon-exchange contributions are numerically substantial for a wide range of momentum transfers accessible in the current and forthcoming collider experiments. Including further the (formally) power-suppressed soft contributions due to the celebrated Feynman mechanism, we then perform the state-of-the-art analysis of the Dirac electromagnetic nucleon form factors from first field-theoretical principles, thus allowing for the most robust determinations of the nucleon distribution amplitudes from the direct comparison with the experimental measurements., Comment: 7+4 pages, 4 figures

We accomplish for the first time the next-to-leading-order computation of the weak annihilation contribution to the exclusive electroweak penguin decays $B \to \left \{K, \pi \right \} \ell^{+} \ell^{-}$ with an energetic light-flavour meson, which is an essential missing piece of the complete QCD correction to the matrix elements of hadronic operators in the weak effective Hamiltonian. Both the hard functions and the jet functions in the perturbative factorization formulae from the short-distance fluctuations at the two distinct scales $m_b$ and $\sqrt{m_b \, \Lambda}$ are determined at ${\cal O}(\alpha_s)$ with the soft-collinear factorization technique. We then demonstrate that the one-loop weak annihilation correction can bring about the noticeable impacts on theory predictions for the CP asymmetries and the isospin asymmetry in the $B \to \pi \ell^{+} \ell^{-}$ decays., Comment: 8 pages, 3 figures

We determine for the first time the renormalization-group (RG) evolution equation for the $B$-meson soft function dictating the non-perturbative strong interaction dynamics of the long-distance penguin contributions to the exclusive $b \to q \ell^{+} \ell^{-}$ and $b \to q \gamma$ decays. The distinctive feature of the ultraviolet renormalization of this fundamental distribution amplitude consists in the novel pattern of mixing positive into negative support for an arbitrary initial condition. The exact solution to this integro-differential RG evolution equation of the bottom-meson soft function is then derived with the Laplace transform technique, allowing for the model-independent extraction of the desired asymptotic behaviour at large/small partonic momenta., Comment: 8 pages, 2 figures

We overview the current status and future perspectives of the QCD-based method of light-cone sum rules. The two main versions of these sum rules, using light-meson and $B$-meson distribution amplitudes are introduced and the most important applications of the method are discussed. We also outline open problems and future perspectives of this method., Comment: Invited review for EPJST, 48 pages, 8 tables

We compute for the first time the next-to-leading-order QCD corrections to the $\bar B_{(s)} \to D_{(s)}^{(\ast)}$ form factors at large hadronic recoil. Both the charm-quark-mass and the strange-quark-mass dependent pieces can generate the leading-power contributions to these form factors. Including further various power-suppressed contributions, we perform the combined fits of the considered form factors to both our large-recoil theory predictions and the lattice QCD results, thus improving upon the previous determinations of the lepton-flavour-universality ratios ${\cal R} (D^{(\ast)})$ significantly., Comment: 6 pages plus Supplemental Material, 3 figures, 1 table, 2 ancillary files

We improve QCD calculations of the $B_{d, s} \to \pi, K$ form factors at large hadronic recoil by implementing the next-to-leading-logarithmic resummation for the obtained leading-power light-cone sum rules in the soft-collinear effective theory (SCET) framework. Additionally, we endeavour to investigate a variety of the subleading-power contributions to these heavy-to-light form factors at ${\cal O}(\alpha_s^0)$, by including the higher-order terms in the heavy-quark expansion of the hard-collinear quark propagator, by evaluating the desired effective matrix element of the next-to-leading-order term in the ${\rm SCET_{I}}$ representation of the weak transition current, by taking into account the off-light-cone contributions of the two-body heavy-quark effective theory matrix elements as well as the three-particle higher-twist corrections from the subleading bottom-meson light-cone distribution amplitudes, and by computing the twist-five and twist-six four-body higher-twist effects with the aid of the factorization approximation. Having at our disposal the SCET sum rules for the exclusive $B$-meson decay form factors, we further explore in detail numerical implications of the newly computed subleading-power corrections by employing the three-parameter model for both the leading-twist and higher-twist $B$-meson distribution amplitudes. Taking advantage of the customary Bourrely-Caprini-Lellouch parametrization for the semileptonic $B_{d, s} \to \pi, K$ form factors, we then determine the correlated numerical results for the interesting series coefficients, by carrying out the simultaneous fit of the exclusive $B$-meson decay form factors to both the achieved SCET sum rule predictions and the available lattice QCD results., Comment: 74 pages, 15 figures

Graphene is a famous truly two-dimensional (2D) material, possessing a cone-like energy structure near the Fermi level and treated as a gapless semiconductor. Its unique properties trigger researchers to find applications of it. The gapless feature shrinks the development of graphene nanoelectronics. Making one-dimensional (1D) strips of graphene nanoribbons (GNRs) could be one of the promising routes to modulating the electronic and optical properties of graphene. The electronic and optical properties of GNRs are highly sensitive to the edge and width. The tunability in electronic and optical properties further implies the possibilities of GNR application. However, the dangling bonds at ribbon edges remain an open question in GNR systems. Various passivation at the ribbon edge might change the essential physical properties. In this work, $5d$ transition-metal elements are considered as the guest atoms at the edges. The geometric structure, energy bands, density of states, charge distribution, and optical transitions are discussed.

We compute for the first time the long-distance penguin contribution to the double radiative $B$-meson decays due to the purely hadronic operators acting with the electromagnetic current in the background soft-gluon field from first field-theoretical principles by introducing a novel subleading $B$-meson distribution amplitude. The numerically dominant penguin amplitude arises from the soft-gluon radiation off the light up-quark loop rather than the counterpart charm-loop effect on account of the peculiar analytical behaviour of the short-distance hard-collinear function. Importantly the long-distance up-quark penguin contribution brings about the substantial cancellation of the known factorizable power correction possessing the same multiplication CKM parameters, thus enabling $B_{d, \, s} \to \gamma \gamma$ to become new benchmark probes of physics beyond the Standard Model., Comment: 7 pages, 2 figures

Graphene is the first truly two-dimensional (2D) material, possessing a cone-like energy spectrum near the Fermi energy and treated as a gapless semiconductor. Its unique properties trigger researchers to find more applications of it, such as high carrier mobility at room temperature, superior thermoconductivity, high modulus and tensile strength, high transparency, and anomalous quantum Hall effect. However, the gapless feature limits the development of graphene nanoelectronics. Making one-dimensional (1D) strips of graphene (i.e., graphene nanoribbons (GNRs)) could be one of the most promising approaches to modulating the electronic and optical properties of graphene. The electronic and optical properties have been theoretically predicted and experimentally verified highly sensitive to the edge and width. The tunable electronic and optical properties further imply the possibilities of GNR application. Recently, the dangling bond problem is under consideration in the GNR system. Various passivation at the ribbon edge might change the physical properties. In this work, some passivation conditions are studied, such as alkalization and hydrogenation.

The widely use of lithium-ion (Li-ion) batteries in various fields, from portable products to large-scale energy storage systems, has revolutionized our daily life. The 2019 Nobel Prize in Chemistry has been awarded to John B. Goodenough, M. Stanley Whittingham, and Akira Yoshino for their contributions in developing Li-ion batteries. Although Li-ion batteries are currently on-growing research topics, lithium availability is still a problem for mass production. In contrast to lithium, sodium resources are almost unlimited on Earth, and sodium is one of the most abundant elements in the Earth's crust. Hence, sodium-ion (Na-ion) batteries as a counterpart of Li-ion batteries have the potential to serve as the next-generation batteries. In this work, a brief history and recent development of Na-ion batteries are described. The fundamental physical and electronic properties, such as geometric structures, band structure, density of states, and spatial charge distributions, of Na-intercalation compounds are discussed. The outlook of Na-ion batteries is given at the last.

We accomplish the analytical computation of the pure weak annihilation non-leptonic $B$-meson decay amplitudes at leading power in the heavy quark expansion. The novel observation regarding such fundamental hadronic quantities is that adding the missing hard-collinear contribution on top of the hard gluon exchange effect eliminates rapidity divergences entering the convolution integrals of factorization formulae. Subsequently we identify the perturbative enhancement mechanism due to the penguin contractions of the current-current operators from the weak effective Hamiltonian, which yields the significant impacts on the CP violating observables., Comment: 5+2 pages, 1 figure

We investigate the subleading-power corrections to the exclusive $B\to D \ell \nu_\ell$ form factors at ${\cal O} (\alpha_s^0)$ in the light-cone sum rules (LCSR) framework by including the two- and three-particle higher-twist contributions from the $B$-meson light-cone distribution amplitudes up to the twist-six accuracy, by taking into account the subleading terms in expanding the hard-collinear charm-quark propagator, and by evaluating the hadronic matrix element of the subleading effective current $\bar q \, \gamma_{\mu} \, i \not\!\!{D}_\perp / (2 \, m_b) \, h_v$. Employing further the available leading-power results for the semileptonic $B \to D$ form factors at the next-to-leading-logarithmic level and combining our improved LCSR predictions with the recent lattice determinations, we then carry out a comprehensive phenomenological analysis on the semi-leptonic $B\to D \ell \nu_\ell$ decay. We extract $|V_{cb}| = \big( 40.2^{+0.6}_{-0.5} {\big |_{\rm th}}\,\, {}^{+1.4}_{-1.4} {\big |_{\rm exp}} \big)\times 10^{-3}$ ($|V_{cb}| = \big( 40.9^{+0.6}_{-0.5} {\big |_{\rm th}}\,\, {}^{+1.0}_{-1.0} {\big |_{\rm exp}} \big)\times 10^{-3}$) using the BaBar (Belle) experimental data, and particularly obtain for the gold-plated ratio $R(D) = 0.302\pm 0.003$., Comment: 28 pages plus appendices and references, 6 figures; v2: matches published version

Employing the QCD factorization formalism we compute $B_{u}^{-} \to \gamma^{\ast} \, \ell \, \bar \nu_{\ell}$ form factors with an off-shell photon state possessing the virtuality of order $m_b \, \Lambda_{\rm QCD}$ and $m_b^2$, respectively, at next-to-leading order in QCD. Perturbative resummation for the enhanced logarithms of $m_b / \Lambda_{\rm QCD}$ in the resulting factorization formulae is subsequently accomplished at next-to-leading logarithmic accuracy with the renormalization-group technique in momentum space. In particular, we derive the soft-collinear factorization formulae for a variety of the subleading power corrections to the exclusive radiative $B_{u}^{-} \to \gamma^{\ast} \, W^{\ast}$ form factors with a hard-collinear photon at ${\cal O}(\alpha_s^{0})$. We further construct the complete set of the angular observables governing the full differential distribution of the four-body leptonic decays $B_{u}^{-} \to \ell^{\prime} \, \bar \ell^{\prime} \, \ell \, \bar \nu_{\ell}$ with $\ell, \, \ell^{\prime} \in \{ e, \, \mu \}$ and then perform an exploratory phenomenological analysis for a number of decay observables accessible at the LHCb and Belle II experiments, with an emphasis on the systematic uncertainties arising from the shape parameters of the leading-twist $B$-meson light-cone distribution amplitude in heavy quark effective theory., Comment: 58 pages, 11 figures

We report on the fully analytic calculation of the leading-power contribution to the photon-pion transition form factor $\gamma \, \gamma^{\ast} \to \pi^0$ at two loops in QCD. The applied techniques are based on hard-collinear factorization, together with modern multi-loop methods. We focus both, on the technical details such as the treatment of evanescent operators, and the phenomenological implications. Our results indicate that the two-loop correction is numerically comparable to the one-loop effect in the same kinematic domain. We also demonstrate that our results will play a key role in disentangling various models for the twist-two pion distribution amplitude thanks to the envisaged precision at Belle II., Comment: 12 pages, 5 figures. Contribution to the 15th International Symposium on Radiative Corrections (RADCOR) and the XIX Workshop on Radiative Corrections for the LHC and Future Colliders (LoopFest)

We accomplish the complete two-loop computation of the leading-twist contribution to the photon-pion transition form factor $\gamma \, \gamma^{\ast} \to \pi^0$ by applying the hard-collinear factorization theorem together with modern multi-loop techniques. The resulting predictions for the form factor indicate that the two-loop perturbative correction is numerically important. We also demonstrate that our results will play a key role in disentangling various models of the twist-two pion distribution amplitude thanks to the envisaged precision at Belle II., Comment: Published version in Physical Review Letters. Coefficient functions in the electronic form are given in the ancillary file

We revisit the calculation of the strong couplings $D^*D\pi$ and $B^*B\pi$ from the QCD light-cone sum rules using the pion light-cone distribution amplitudes. The accuracy of the correlation function, calculated from the operator product expansion near the light-cone, is upgraded by taking into account the gluon radiative corrections to the twist-3 terms. The double spectral density of the correlation function, including the twist-2, 3 terms at ${\cal O} (\alpha_s)$ and the twist-4 LO terms, is presented in an analytical form for the first time. This form allows us to use various versions of the quark-hadron duality regions in the double dispersion relation underlying the sum rules. We predict $g_{D^*D\pi}=14.1^{+1.3}_{-1.2}$ and $g_{B^*B\pi}=30.0^{+2.6}_{-2.4}$ when the decay constants of heavy mesons entering the light-cone sum rule are taken from lattice QCD results. We compare our results with the experimental value for the charmed meson coupling and with the lattice QCD calculations., Comment: 41 pages, 3 figures, a few comments added, the version published in JHEP

Employing the systematic framework of soft-collinear effective theory (SCET) we perform an improved calculation of the leading-power contributions to the double radiative $B_{d, \, s}$-meson decay amplitudes in the heavy quark expansion. We then construct the QCD factorization formulae for the subleading power contributions arising from the energetic photon radiation off the constituent light-flavour quark of the bottom meson at tree level. Furthermore, we explore the factorization properties of the subleading power correction from the effective SCET current $J^{(A2)}$ at ${\cal O} (\alpha_s^0)$. The higher-twist contributions to the $B_{d, \, s} \to \gamma \gamma $ helicity form factors from the two-particle and three-particle bottom-meson distribution amplitudes are evaluated up to the twist-six accuracy. In addition, the subleading power weak-annihilation contributions from both the current-current and QCD penguin operators are taken into account at the one-loop accuracy. We proceed to apply the operator-production-expansion-controlled dispersion relation for estimating the power-suppressed soft contributions to the double radiative $B_{d, \, s}$-meson decay form factors. Phenomenological explorations of the radiative $B_{d, \, s} \to \gamma \, \gamma$ decay observables in the presence of the neutral-meson mixing, including the CP-averaged branching fractions, the polarization fractions and the time-dependent CP asymmetries, are carried out subsequently with an emphasis on the numerical impacts of the newly computed ingredients together with the theory uncertainties from the shape parameters of the HQET bottom-meson distribution amplitudes., Comment: 58 pages, 7 figures

We calculate the differential branching fraction, lepton forward-backward asymmetry and direct CP asymmetry for $B_{d,s}\to\gamma\ell\bar{\ell}$ decays with an energetic photon. We employ factorization methods, which result in rigorous next-to-leading order predictions in the strong coupling at leading power in the large-energy/heavy-quark expansion, together with estimates of power corrections and a resonance parameterization of sub-leading power form factors in the region of small lepton invariant mass $q^2$. The $B_{d,s}\to\gamma\ell\bar{\ell}$ decay shares features of the charged-current decay $B_u \to \gamma\ell\bar\nu_\ell$, and the FCNC decays $B\to K^{(*)}\ell\bar\ell$. As in the former, the leading-power decay rates can be expressed in terms of the $B$-meson light-cone distribution amplitude and short-distance factors. However, similar to $B\to K^{(*)}\ell\bar\ell$, four-quark and dipole operators contribute to the $B_{d,s}\to\gamma\ell\bar{\ell}$ decay in an essential way, limiting the calculation to $q^2\lesssim 6\,$GeV$^2$ below the charmonium resonances in the lepton invariant mass spectrum. A detailed analysis of the main observables and theoretical uncertainties is presented., Comment: 50 pages, LaTeX; v2: Corrected sign typos in (3.48) and (3.52), results not affected

We revisit QCD calculations of radiative heavy meson decay form factors by including the subleading power corrections from the twist-two photon distribution amplitude at next-to-leading-order in $\alpha_s$ with the method of the light-cone sum rules (LCSR). The desired hard-collinear factorization formula for the vacuum-to-photon correlation function with the interpolating currents for two heavy mesons is constructed with the operator-product-expansion technique in the presence of evanescent operators. Applying the background field approach, the higher twist corrections from both the two-particle and three-particle photon distribution amplitudes are further computed in the LCSR framework at leading-order in QCD, up to the twist-four accuracy. Combining the leading power "point-like" photon contribution at tree level and the subleading power resolved photon corrections from the newly derived LCSR, we update theory predictions for the nonperturbative couplings describing the electromagnetic decay processes of the heavy mesons $H^{\ast \, \pm} \to H^{\pm} \, \gamma$, $H^{\ast \, 0} \to H^{0} \, \gamma$, $H_s^{\ast \, \pm} \to H_s^{\pm} \, \gamma$ (with $H=D, \, B$). Furthermore, we perform an exploratory comparisons of our sum rule computations of the heavy-meson magnetic couplings with the previous determinations based upon different QCD approaches and phenomenological models., Comment: 39 pages, 4 figures

A new method for the model-independent determination of the light-cone distribution amplitude (LCDA) of the $B$-meson in heavy quark effective theory (HQET) is proposed by combining the large momentum effective theory (LaMET) and the numerical simulation technique on the Euclidean lattice. We demonstrate the autonomous scale dependence of the non-local quasi-HQET operator with the aid of the auxiliary field approach, and further determine the perturbative matching coefficient entering the hard-collinear factorization formula for the $B$-meson quasi-distribution amplitude at the one-loop accuracy. These results will be crucial to explore the partonic structure of heavy-quark hadrons in the static limit and to improve the theory description of exclusive $B$-meson decay amplitudes based upon perturbative QCD factorization theorems., Comment: 7 pages, 2 figures

Applying the vacuum-to-$B$-meson correlation functions with an interpolating current for the light vector meson we construct the light-cone sum rules (LCSR) for the "effective" form factors $\xi_{\parallel}(n \cdot p)$, $\xi_{\perp}(n \cdot p)$, $\Xi_{\parallel}(\tau, n \cdot p)$ and $\Xi_{\perp}(\tau, n \cdot p)$, defined by the corresponding hadronic matrix elements in soft-collinear effective theory (SCET), entering the leading-power factorization formulae for QCD form factors responsible for $B \to V \ell \bar \nu_{\ell}$ and $B \to V \ell \bar \ell$ decays at large hadronic recoil at next-to-leading-order in QCD. The light-quark mass effect for the local SCET form factors $\xi_{\parallel}(n \cdot p)$ and $\xi_{\perp}(n \cdot p)$ is also computed from the LCSR method with the $B$-meson light-cone distribution amplitude $\phi_B^{+}(\omega, \mu)$ at ${\cal O}(\alpha_s)$. Furthermore, the subleading power corrections to $B \to V$ form factors from the higher-twist $B$-meson light-cone distribution amplitudes are also computed with the same method at tree level up to the twist-six accuracy. Having at our disposal the LCSR predictions for $B \to V$ form factors, we further perform new determinations of the CKM matrix element $|V_{ub}|$ from the semileptonic $B \to \rho \, \ell \, \bar \nu_{\ell}$ and $B \to \omega \, \ell \, \bar \nu_{\ell}$ decays, and predict the normalized differential branching fractions and the $q^2$-binned $K^{\ast}$ longitudinal polarization fractions of the exclusive rare $B \to K^{\ast} \, \nu_{\ell} \, \bar \nu_{\ell}$ decays., Comment: 76 pages, 15 figures

We update QCD calculations of $B \to \pi, K$ form factors at large hadronic recoil by including the subleading-power corrections from the higher-twist $B$-meson light-cone distribution amplitudes (LCDAs) up to the twist-six accuracy and the strange-quark mass effects at leading-power in $\Lambda/m_b$ from the twist-two $B$-meson LCDA $\phi_B^{+}(\omega, \mu)$. The higher-twist corrections from both the two-particle and three-particle $B$-meson LCDAs are computed from the light-cone QCD sum rules (LCSR) at tree level. In particular, we construct the local duality model for the twist-five and -six $B$-meson LCDAs, in agreement with the corresponding asymptotic behaviours at small quark and gluon momenta, employing the QCD sum rules in heavy quark effective theory at leading order in $\alpha_s$. The strange quark mass effects in semileptonic $B \to K$ form factors yield the leading-power contribution in the heavy quark expansion, consistent with the power-counting analysis in soft-collinear effective theory, and they are also computed from the LCSR approach due to the appearance of the rapidity singularities. We further explore the phenomenological aspects of the semileptonic $B \to \pi \ell \nu$ decays and the rare exclusive processes $B \to K \nu \nu$, including the determination of the CKM matrix element $|V_{ub}|$, the normalized differential $q^2$ distributions and precision observables defined by the ratios of branching fractions for the above-mentioned two channels in the same intervals of $q^2$., Comment: 36 pages, 9 figures

Applying the method of light-cone sum rules with photon distribution amplitudes, we compute the subleading-power correction to the radiative leptonic $B \to \gamma \ell \nu$ decay, at next-to-leading order in QCD for the twist-two contribution and at leading order in $\alpha_s$ for the higher-twist contributions, induced by the hadronic component of the collinear photon. The leading-twist hadronic photon effect turns out to preserve the symmetry relation between the two $B \to \gamma$ form factors due to the helicity conservation, however, the higher-twist hadronic photon corrections can yield symmetry-breaking effect already at tree level in QCD. Using the conformal expansion of photon distribution amplitudes with the non-perturbative parameters estimated from QCD sum rules, the twist-two hadronic photon contribution can give rise to approximately 30\% correction to the leading-power "direct photon" effect computed from the perturbative QCD factorization approach. In contrast, the subleading-power corrections from the higher-twist two-particle and three-particle photon distribution amplitudes are estimated to be of ${\cal O} (3 \sim 5\%)$ with the light-cone sum rule approach. We further predict the partial branching fractions of $B \to \gamma \ell \nu $ with a photon-energy cut $E_{\gamma} \geq E_{\rm cut}$, which are of interest for determining the inverse moment of the leading-twist $B$-meson distribution amplitude thanks to the forthcoming high-luminosity Belle II experiment at KEK., Comment: 36 pages, 9 figures