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B¯s0→Kπ,KK decays and effects of the next-to-leading order contributions

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Physical Review D 2014年第7期89卷 074046-074046页

作者： Jing-Jing Wang Dong-Ting Lin Wen Sun Zhong-Jian Ji Shan Cheng Zhen-Jun Xiao Department of Physics Institute of Theoretical Physics Nanjing Normal University Nanjing Jiangsu 210023 People’s Republic of China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing 210023 People’s Republic of China

By employing the perturbative QCD (pQCD) factorization approach, we calculate the branching ratios and charge parity (CP)-violating asymmetries of the four B¯s0→Kπ and KK decays, with the inclusion of all known next-to-leading order (NLO) contributions. We find numerically that (a) the NLO contribution can interfere with the leading order (LO) part constructively or destructively for different decay modes; (b) the NLO contribution leads to a 22% decrease for the central values of the LO pQCD prediction for Br(B¯s0→K+π−), but ∼50% enhancement to the other three considered B¯s decays, the agreement between the central values of the pQCD predictions and the data are therefore improved effectively after the inclusion of the NLO contributions; (c) for both B¯s0→K+π− and B¯s0→K+K− decays, the NLO pQCD predictions for the direct and mixing induced CP-violating asymmetries agree well with the measured values in both the sign and the magnitude; and (d) the theoretical errors of the pQCD predictions for decay rates are about 35% of the cental values and larger than that of the relevant data.

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Study of Bs→K(*)ℓ+ℓ− decays in the PQCD factorization approach with lattice QCD input

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Physical Review D 2020年第1期102卷 013001-013001页

作者： Su-Ping Jin Xue-Qing Hu Zhen-Jun Xiao Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing Jiangsu 210023 People’s Republic of China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing 210023 People’s Republic of China

In this paper, we studied systematically the semileptonic decays B¯s→K(*)ℓ+ℓ− with l−=(e−,μ−,τ−) by using the perturbative QCD (PQCD) and the “PQCD+Lattice” factorization approach, respectively. We first evaluated all relevant form factors Fi(q2) in the low-q2 region using the PQCD approach, and we also took the available lattice QCD results at the end point qmax2 as additional inputs to improve the extrapolation of the form factors to the high-q2 region. We calculated the branching ratios and twelve other kinds of physical observables. From our studies, we find the following points: (a) for B¯s→Kl+l− decays, the PQCD and PQCD+Lattice predictions for branching ratios B(B¯s→Kl+l−), the ratios of the branching ratios RKeμ and RKμτ, and the longitudinal polarization asymmetry of the leptons PL agree well within errors; (b) the PQCD and PQCD+Lattice predictions for the CP-averaged branching ratio B(B¯s→K*μ+μ−) are (3.17−0.78+0.95)×10−8 and (2.48−0.50+0.56)×10−8 respectively, which agree well with the LHCb measured value (2.9±1.1)×10−8 and the light-cone sum rule prediction; (c) for the ratios RK*eμ and RK*μτ, the PQCD and PQCD+Lattice predictions agree well with each other and have a small error less than 10%; (d) for the direct CP asymmetries ACP of all considered decay modes, they are always very small as expected: less than 5% in magnitude; (e) for the angular observables P1,2,3 and P4,5,6,8′, our theoretical predictions for each kind of lepton are consistent within errors; (f) the theoretical predictions of the angular observables P3 and P6′ are less than 10−2 in size, but the magnitude of P1,2 and P4,5′ are larger than 0.2; and (g) the PQCD and PQCD+Lattice predictions of the binned values of all considered observables in the two q2 bins [0.1–0.98] GeV2 and [1.1–6] GeV2 generally agree with each other and are also consistent with the light-cone sum rule results within errors. We believe that above predictions could be tested by future LHCb and Belle-II experiment

关键词： Electroweak interaction Flavor changing neutral currents Form factors Particle interactions Particle phenomena

Thermodynamically Consistent Hybrid Computational Models for Fluid-Particle Interactions

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SSRN

SSRN 2023年

作者： Hong, Qi Wang, Qi School of Mathematics Nanjing University of Aeronautics and Astronautics Nanjing211106 China MIIT Nanjing211106 China Key Laboratory of Numerical Simulation for Large Scale Complex Systems Nanjing Normal University Ministry of Education Nanjing210023 China Department of Mathematics University of South Carolina ColumbiaSC29208 United States

We introduce a novel computational framework designed to explore the dynamic interactions between fluid and solid particles or structures immersed in a viscous fluid medium. This innovative framework harnesses the power of the phase-field-embedding method, in which each solid component, whether rigid or elastic, is characterized by a volume-preserving phase field. The unified velocity within the fluid-solid ensemble governs the movement of both solid particles and the surrounding fluid, specifically for passive particles. Active particles, however, are not only influenced by this unified velocity but are also driven by their self-propelling velocities. To capture exclusive volume interactions among particles and between particles and boundaries, we employ repulsive potential forces at a coarser scale. These forces effectively model repulsion and collision effects. Rigid particles maintain structural integrity by enforcing a zero velocity gradient tensor within their spatial domains, necessitating the introduction of a constraining stress tensor. In contrast, elastic particles are governed by a quasi-linear constitutive equation describing the elastic stress within their domains, allowing for accurate modeling of their deformations. The motion of solid particles is tracked by monitoring the dynamics of their centers of mass. This approach facilitates the development of a hybrid, thermodynamically consistent hydrodynamic model applicable to both rigid and elastic particles. Adhering to the generalized Onsager principle, this model spans the entire computational domain. To numerically solve this thermodynamically consistent model for elastic particles, we present a structure-preserving numerical algorithm. Notably, in the limit of an infinite elastic modulus, this algorithm converges to the one employed for modeling rigid particles. Finally, we substantiate the effectiveness, accuracy, and stability of our proposed scheme through a series of numerical experiments. Thes

关键词： Hydrodynamics

Arbitrarily high-order structure-preserving schemes for the Gross-Pitaevskii equation with angular momentum rotation in three dimensions

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arXiv 2020年

作者： Cui, Jin Wang, Yushun Jiang, Chaolong Department of Basic Sciences Nanjing Vocational College of Information Technology Nanjing210023 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems School of Mathematical Sciences Nanjing Normal University Nanjing210023 China School of Statistics and Mathematics Yunnan University of Finance and Economics Kunming650221 China

In this paper, we design a novel class of arbitrarily high-order structure-preserving numerical schemes for the time-dependent Gross-Pitaevskii equation with angular momentum rotation in three dimensions. Based on the idea of the scalar auxiliary variable approach which is proposed in the recent papers [J. Comput. Phys., 416 (2018) 353-407 and SIAM Rev., 61(2019) 474-506] for developing energy stable schemes for gradient flow systems, we firstly reformulate the Gross-Pitaevskii equation into an equivalent system with a modified energy conservation law. The reformulated system is then discretized by the Gauss collocation method in time and the standard Fourier pseudo-spectral method in space, respectively. We show that the proposed schemes can preserve the discrete mass and modified energy exactly. Numerical results are addressed to verify the efficiency and high-order accuracy of the proposed schemes. Copyright © 2020, The Authors. All rights reserved.

关键词： Bose-Einstein condensation

Next-to-leading order corrections to B→ρ transition in the kT factorization

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Physical Review D 2019年第1期99卷 016007-016007页

作者： Jun Hua Ya-Lan Zhang Zhen-Jun Xiao Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing Jiangsu 210023 People’s Republic of China Department of Faculty of Mathematics and Physics Huaiyin Institute of Technology Huaian Jiangsu 223001 People’s Republic of China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing 210023 People’s Republic of China

In this paper, we investigate the factorization hypothesis step by step for the exclusive process B→ρ at next-to-leading order (NLO), and then we extend our results to the kT factorization frame. We show that the soft divergence from the specific NLO diagrams will cancel each other at the quark level, while the remaining collinear divergence can be absorbed into the NLO wave functions of the mesons involved. The full NLO amplitudes can be factorized into two parts: the B meson and the ρ meson NLO wave functions containing the collinear divergence and the finite leading order hard kernels. We give the general expressions of the nonlocal hadron matrix for the NLO B meson and ρ meson wave functions and the analytical results of factorization for the combinations of different twist parts.

关键词： Form factors

Asymptotic critical behavior of holographic phase transition at finite topological charge - the spectrum of excited states becomes continuous at T = 0

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arXiv 2021年

作者： Nguyen, Toan T. Phat, Tran Huu Key Laboratory for Multiscale Simulation of Complex Systems Department of Theoretical Physics University of Science Vietnam National University – Hanoi 334 Nguyen Trai street Thanh Xuan Hanoi100000 Viet Nam Vietnam Atomic Energy Commission 59 Ly Thuong Kiet street Hoan Kiem Hanoi100000 Viet Nam

Within the framework of AdS/CFT duality, excited states of the conformal field living at the global AdS boundary of a four-dimensional spacetime Einstein gravity are investigated analytically in the probe limit where the field equations are linearized. At asymptotically large values, the threshold chemical potential for the appearance of excited condensate states are discrete, equal spacing, with the gap approaches zero logarithmically in the limit T → 0. Remarkably, numerical results show that, this behavior applies even for states as low as for the first or the second excited state of the condensate. This is especially significant on the liquid side of the black hole van der Waals - like phase transition (small or zero topological charge) where there seems to be no gap between the ground state and the first excited state at zero temperature. We postulate that, at the exact limit T = 0 where the gap is zero, the spectrum of threshold chemical potentials becomes continuous, all excited states of the condensate are activated above a finite chemical potential, suggesting a new quantum phase transition as a function of the chemical potential. Previous studies have largely missed this continuous spectrum of excited states in the T → 0 limit. This fact should be taken into account carefully in AdS/CFT duality studies. Copyright © 2021, The Authors. All rights reserved.

关键词： Excited states

Quasi-two-body decays B(s)→D(ρ(1450), ρ(1700))→Dππ in the perturbative QCD factorization approach

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Physical Review D 2017年第9期96卷 093011-093011页

作者： Ai-Jun Ma Ya Li Wen-Fei Wang Zhen-Jun Xiao Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing Jiangsu 210023 People’s Republic of China Institute of Theoretical Physics Shanxi University Taiyuan Shanxi 030006 People’s Republic of China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing Jiangsu 210023 People’s Republic of China

By employing a framework for the quasi-two-body decays in the perturbative QCD (PQCD) factorization approach, we calculate the branching ratios of the decays B(s)→D(ρ(1450), ρ(1700))→Dππ with D=(D(s),D¯(s)). The pion vector form factor Fπ, acquired from a BABAR Collaboration analysis of e+e−→π+π−(γ) data, is involved in the two-pion distribution amplitudes ΦππI=1. The PQCD predictions for the branching ratios of the considered quasi-two-body decays are in the range of 10−10–10−4. The PQCD predictions for B(B0→D¯0(ρ0(1450),ρ0(1700))→D¯0π+π−) agree well with the measured values as reported by LHCb if one takes still large theoretical errors into account. Unlike the traditional way of the PQCD approach, one can extract the decay rates for the two-body decays B(s)→D(ρ(1450),ρ(1700)) from the results of the corresponding quasi-two-body decays. The PQCD predictions for B(B(s)→Dρ(1450)) and B(B(s)→Dρ(770)) are similar in magnitude: an interesting relation to be tested by future experimental measurements.

关键词： Electroweak interaction Form factors Particle decays Particle phenomena

On the triplet of holographic phase transition

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arXiv 2021年

作者： Phat, Tran Huu Nguyen, Toan T. Vietnam Atomic Energy Commission 59 Ly Thuong Kiet street Hoan Kiem Hanoi100000 Viet Nam Key Laboratory for Multiscale Simulation of Complex Systems Department of Theoretical Physics University of Science Vietnam National University − Hanoi 334 Nguyen Trai street Thanh Xuan Hanoi100000 Viet Nam

We start from an Einstein − Maxwell system coupled with a charged scalar field in Anti−de Sitter space−time. In the setup where the pressure P is identified with the cosmological constant, the AdS black hole (BH) undergoes the phase transition from small to large BHs, which is similar to the transition from liquid to gas in the van der Waals theory. Based on this framework, we study the triplet of holographic superconducting states, consisting of ground state and two lowest excited states. Our numerical calculations show that the pressure variation in the bulk creates a mechanism in the boundary which causes changes in the physical properties of excited states, namely: a) when the pressure P is higher than the critical pressure Pc (P > Pc) of the phase transition from small to large BHs the ground state and the first excited state are superconducting states while the second excited state is the normal one. However, at lower pressure, P ≤ Pc, the ground state is solely the superconducting state. We conjecture that the precedent phenomena could take place when the scalar field in the bulk is replaced by other matter fields. Copyright © 2021, The Authors. All rights reserved.

关键词： Ground state

On semilinear Tricomi equations with critical exponents or in two space dimensions

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arXiv 2017年

作者： He, Daoyin Witt, Ingo Yin, Huicheng Department of Mathematics and IMS Nanjing University Nanjing210093 China Mathematical Institute University of Göttingen Bunsenstr. 3-5 GöttingenD-37073 Germany School of Mathematical Sciences Jiangsu Provincial Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing210023 China

This paper is a complement of our recent works on the semilinear Tricomi equations in [8] and [9]. For the semilinear Tricomi equation ∂t2u−t∆u = |u|p with initial data (u(0, ·), ∂tu(0, ·)) = (u0, u1), where t ≥ 0, x ∈ Rn (n ≥ 3), p > 1, and ui ∈ C0∞(Rn) (i = 0, 1), we have shown in [8] and [9] that there exists a critical exponent pcrit(n) > 1 such that the solution u, in general, blows up in finite time when 1 crit(n), and there is a global small solution for p > pcrit(n). In the present paper, firstly, we prove that the solution of ∂t2u − t∆u = |u|p will generally blow up for the critical exponent p = pcrit(n) and n ≥ 2, secondly, we establish the global existence of small data solution to ∂t2u − t∆u = |u|p for p > pcrit(n) and n = 2. Thus, we have given a systematic study on the blowup or global existence of small data solution u to the equation ∂t2u − t∆u = |u|p for n ≥ 2.35L70, 35L65, 35L67 Copyright © 2017, The Authors. All rights reserved.

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