arXiv subjects

Jia-Wei Zhang

Publications and source records attributed to Jia-Wei Zhang.

At least 19 recordsLinked to original sources

arXiv2026

A Class of Exact Single-Field Inflationary Solutions beyond Slow Roll

We construct exact solutions for single-field inflaton dynamics without invoking the slow-roll approximation. A suitable change of variables reduces the background equation to an Abel equation of the first kind. Although a generic Abel equation is not analytically solvable, we identify a class of inflaton potentials for which the transformed equation admits exact solutions. The resulting framework contains constant-roll inflation as a special case and also accommodates solutions with a constant second Hubble-flow parameter. We analyze the linear local attractor behavior and superhorizon evolution of these rolling backgrounds. Using the public joint CMB likelihood contours in the $(n_s,r)$ plane, we identify compatible parameter regions and show that one rolling branch can also yield $50\leq N_*<60$. Direct numerical evolution of the scalar and tensor modes at representative points validates the local-index predictions to better than $7\times10^{-4}$ in $n_s$ and $2\times10^{-6}$ in $r$. The exact family extends beyond slow roll, although the observationally selected regions displayed here lie close to the slow-roll regime.

astro-ph.CO↗

arXiv2026

Exclusive Determination of $|V_{cb}|$ from Semileptonic Decays $B\to D^{(*)}\ell ν_{\ell}$

We present an updated exclusive determination of the CKM matrix element $|V_{cb}|$ from the semileptonic decays $B\to D^{(*)}\ell\barν_{\ell}$. Our analysis combines the latest Belle II measurements, updated lattice-QCD calculations of the $B\to D^{(*)}$ form factors at small hadronic recoil, and correlated large-recoil SCET sum-rule predictions incorporating next-to-leading-order QCD corrections and several power-suppressed contributions. We consider three fit scenarios with progressively enlarged input sets and find that the inclusion of the large-recoil sum-rule constraints substantially reduces the form-factor uncertainties. From the full global fit, we obtain$|V_{cb}|=(39.18 \pm0.47)\times10^{-3}$. Using the combined lattice-QCD and LCSR fit, we predict $R(D)=0.3069\pm0.0080,\qquad R(D^*)=0.2548\pm0.0043$, and provide differential decay distributions in the momentum transfer and angular variables for both the muon and tau channels. Comparisons of the individual and correlated predictions for $R(D)$ and $R(D^*)$ with the experimental averages reveal a persistent tension. In particular, our theoretical 68\% confidence region shows little overlap with the experimental average. All correlations among the fitted parameters are retained in the uncertainty propagation. Our results therefore provide updated Standard Model benchmarks for tests of lepton-flavor universality. Improved lattice-QCD calculations, sum-rule predictions, and Belle II measurements will be essential for determining whether the remaining discrepancies originate from theoretical systematic uncertainties or from physics beyond the Standard Model.

hep-ph↗

arXiv2026

Angular and invariant-mass observables in the four-body Higgs decay $h\to\ell\barν_\ell\bar{\ell}^\primeν_{\ell^\prime}$

We study the angular distribution of the Higgs boson decay $h\to\ell\barν_\ell\bar{\ell}^\primeν_{\ell^\prime}$ with $\ell\neq\ell^\prime$. Due to the presence of two undetected neutrinos, a complete angular analysis is not experimentally feasible. To overcome this, we reorganize the kinematics from the conventional lepton-neutrino pairs into a charged-lepton pair and a neutrino pair, i.e.~$\ell\bar{\ell}^\prime$ and $\barν_\ellν_{\ell^\prime}$. This allows us to express the differential decay rate in terms of experimentally accessible variables, including the invariant mass squared of the neutrino pair. Using the effective field theory framework, we derive this rate and integrate over the neutrino-associated angles. This parametrization provides a clean and measurable angular distribution, offering a new probe of the $hWW$ coupling and possible beyond-the-Standard-Model contributions.

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arXiv2026

Controlling Liouvillian topological phases via Hamiltonian band topology under chiral symmetry

We establish a direct connection between Hamiltonian band topology and the Liouvillian spectral winding of open quantum systems with quadratic dissipations. This allows the band topology to act as a knob for controlling Liouvillian topology and corresponding non-equilibrium dynamics. In particular, we show analytically that, for chiral Hamiltonians under sublattice-unidirectional chiral dissipation, the Liouvillian spectral winding depends on the Hamiltonian solely through its band winding number, thereby enabling direct band-topological control of the Liouvillian skin effect. We further identify two distinguished coherent and incoherent Liouvillian skin effects therein: the former hosts a band-topological dark state of the Hamiltonian, whereas the latter yields a mixed steady state driven by dissipative nonreciprocity. Our results establish a systematic framework for topological control of spectral and spatial organization in open quantum systems and provide a unified perspective on topology in Hamiltonian and dissipative dynamics.

quant-ph↗

arXiv2025

Analysis of the Pion Electromagnetic Form Factor with Next-to-Next-to-Leading Order QCD Corrections

NNLO QCD corrections for the pion electromagnetic form factor at large momentum transfer have been recently performed in [Phys. Rev. Lett. 132, 201901 (2024); Phys. Rev. Lett. 134, 221901 (2025)], revealing that the NLO and NNLO contributions are positive and sizeable. Unfortunately, these predictions have been obtained using the conventional scale-setting method and thus they are plagued by large renormalization scale ambiguities. In this paper, we analyze the pion electromagnetic form factor at NNLO by applying the Principle of Maximum Conformality (PMC), which is introduced with the aim of resolving renormalization scheme and scale ambiguities. By applying the PMC, a more precise perturbative QCD (pQCD) prediction for the pion EMFF $Q^2F_π(Q^2)$ without conventional renormalization scale ambiguity can be achieved. This improved pQCD prediction is highly beneficial for the precise determination of the pion light-cone distribution amplitude. We then conduct a comprehensive comparison between theoretical predictions and experimental measurements of the pion EMFF $Q^2F_π(Q^2)$.

hep-ph↗

arXiv2025

$B_{(s)} \to S(a_0(1450), K_0^*(1430), f_0(1500))$ helicity form factors within QCD light-cone sum rules

In this paper, we investigate the helicity form factors (HFFs) of the $B_{(s)}$-meson decay into a scalar meson with a mass larger than 1~GeV, {\it i.e.,} $B \to a_0(1450)$, $B_{(s)} \to K_0^*(1430)$ and $B_{s} \to f_0(1500)$ by using light-cone sum rules approach. We take the standard currents for correlation functions. To enhance the precision of our calculations, we incorporate the next-to-leading order (NLO) corrections and retain the scalar meson twist-3 light-cone distribution amplitudes. Furthermore, we extend the HFFs to the entire physical $q^2$ region employing a simplified $z$-series expansion. At the point of $q^2=1\rm{~GeV^2}$, all NLO contributions to the HFFs are negative, with the maximum contribution around $25\%$. Then, as applications of these HFFs, we analyze the differential decay widths, branching ratios, and lepton polarization asymmetries for the semi-leptonic $B_{(s)} \to S \ell \barν_\ell$, FCNC $B_{(s)} \to S \ell \bar{\ell}$ and rare $B_{(s)} \to S ν\barν$ decays. Our results are consistent with existing studies within uncertainties. The current data still suffer from large uncertainties and need to be measured more precisely, which can lead to a better understanding of the fundamental properties of light scalar mesons.

hep-ph↗

arXiv2024

Five-body $D\to V$ Semileptonic Decays

Our main objective is to derive the decay rate for the semileptonic decays $D\to V\ell^+ν_{\ell}\,(\ell=e,μ)$, where $V$ represents a vector particle. In these decays, the vector particle $V$ decays into three pseudo-scalar particles. To accomplish this, we evaluate the phase-space factor for the five-body decay with a set of eight independent variables which uniquely define a point in the phase space. We further conduct a detailed investigation of the $D\to ω\ell^+ν_{\ell}$, where $ω$ subsequently decays into $π^+π^-π^0$, within the Standard Model and in a general effective field theory description of the weak interactions at low energies. The outcomes of this study have potential applications in the measurement of $D\to ω$ form factors. These measurements can be performed using data obtained from BESIII.

hep-ph↗

arXiv2024

Quasi-two-body decays $B\to P f_0(500)\to Pπ^+π^-$ in the perturbative QCD approach

In this paper, we study the quasi-two-body decays $B\to P f_0(500)\to Pπ^+π^-$ [with $P=(π, K, η, η^{\prime})$] within framework of perturbative QCD (PQCD) factorization approach. With the help of $π$-$π$ distribution amplitude and scalar form factor $F_{ππ}(ω^2)$, we calculate the $CP$ averaged branching fraction and the $CP$ asymmetry for the quasi-two-body decays $B\to P f_0(500)\to Pπ^+π^-$. Taking the quasi-two-body decay $B^+ \to π^+ f_0(500) \to π^+ π^+ π^-$ as an explicit example, we present the behavior of differential branching fraction and direct $CP$ violation versus the $π$-$π$ invariant mass. The total branching fraction and direct $CP$ violation are $\mathcal{B}(B^+\to π^+ [σ\to]π^+π^-) = (1.78 \pm 0.41\pm 0.51) \times 10^{-6}$ and $\mathcal{A}_{CP}(B^+\to π^+ [σ\to]π^+π^-) = (29.8\pm 11.1\pm 13.0)\%$ respectively. Our results could be tested by further experiments.

hep-ph↗

arXiv2024

Chiral quantum heating and cooling with an optically controlled ion

Quantum heat engines and refrigerators are open quantum systems, whose dynamics can be well understood using a non-Hermitian formalism. A prominent feature of non-Hermiticity is the existence of exceptional points (EPs), which has no counterpart in closed quantum systems. It has been shown in classical systems that dynamical encirclement in the vicinity of an EP, whether the loop includes the EP or not, could lead to chiral mode conversion. Here, we show that this is valid also for quantum systems when dynamical encircling is performed in the vicinity of their Liouvillian EPs (LEPs) which include the effects of quantum jumps and associated noise - an important quantum feature not present in previous works. We demonstrate, using a Paul-trapped ultracold ion, the first chiral quantum heating and refrigeration by dynamically encircling a closed loop in the vicinity of an LEP. We witness the cycling direction to be associated with the chirality and heat release (absorption) of the quantum heat engine (quantum refrigerator). Our experiments have revealed that not only the adiabaticity-breakdown but also the Landau-Zener-Stückelberg process play an essential role during dynamic encircling, resulting in chiral thermodynamic cycles. Our observations contributes to further understanding of chiral and topological features in non-Hermitian systems and pave a way to exploring the relation between chirality and quantum thermodynamics.

quant-ph↗

arXiv2024

Improved analysis of double $J/ψ$ production in $Z$-boson decay

In this paper, we present an improved calculation for the decay rate of the rare $Z$-boson decay into $J/ψ+ J/ψ$. This decay is dominated by the photon fragmentation mechanism, i.e., the transition $Z\to J/ψ+ γ^{*}$ followed by the fragmentation $γ^{*}\to J/ψ$. In our calculation, the amplitude of $γ^{*}\to J/ψ$ is extracted from the measured value of $Γ(J/ψ\to e^+ e^-)$, and the amplitude of $Z\to J/ψ+ γ^{*}$ is calculate through the light-cone approach. The higher-order QCD and relativistic corrections in the amplitude of $γ^{*}\to J/ψ$ and the large logarithms of $m_{_Z}^2/m_c^2$ that appear in the amplitude of $Z\to J/ψ+ γ^{*}$ are resummed in our calculation. Besides, the non-fragmentation amplitude is calculated based on the NRQCD factorization, and the next-to-leading order QCD and relativistic corrections are included. The obtained branching fraction for this $Z$ decay channel is $8.66 ^{+1.48} _{-0.69}\times 10^{-11}$.

hep-ph↗

arXiv2023

Investigating $Z_{cs}(3985)$ and $Z_{cs}(4000)$ exotic states in $Λ_b\to Z^-_{cs}p$ decays

We study the $Z_{cs}(3985)$ and $Z_{cs}(4000)$ exotic states in the decays of $Λ_b$ baryons through a molecular scenario. In the final state interaction, the $Λ_b\to Λ_c^+ D_s^{(*)-}$ decays are followed by the $Λ_c^+ D_s^{(*)-}$ to $Z^-_{cs}p$ rescatterings via exchange of a $D^{(*)}$ meson. We predict a branching fraction of $(3.1^{+1.4}_{-2.6})\times 10^{-4}$ for $Λ_b\to Z^-_{cs}p$, which can be measured in the $Λ_b\to J/ψK^{(*)-}p$ decay. This study proposes a new approach to test the molecular model, and guides future experimental searches for the $Z_{cs}(3985)$ and $Z_{cs}(4000)$.

hep-ph↗

arXiv2021

A new way to test the WIMP dark matter models

In this paper, we investigate the possibility of testing the weakly interacting massive particle (WIMP) dark matter (DM) models by applying the simplest phenomenological model which introduces an interaction term between dark energy (DE) and WIMP DM, i.e., $Q = 3γ_{DM} Hρ_{DM}$. In general, the coupling strength $γ_{DE}$ is close to $0$ as the interaction between DE and WIMP DM is very weak, thus the effect of $γ_ {DE}$ on the evolution of $Y$ associated with DM energy density can be safely neglected. Meanwhile, our numerical calculation also indicates that $x_f\approx20$ is associated with DM freeze-out temperature, which is the same as the vanishing interaction scenario. As for DM relic density, it will be magnified by $\frac{2-3γ_{DM}}{2}[{2πg_* m_{DM}^3}/{(45 s_0 x_f^3})]^{γ_{DM}}$ times, which provides a new way to test WIMP DM models. As an example, we analyze the case in which WIMP DM is a scalar DM. (SGL+SNe+Hz) and (CMB+BAO+SNe) cosmological observations will give $γ_{DM}=0.134^{+0.17}_{-0.069}$ and $γ_{DM}=-0.0008\pm0.0016$, respectively. After further considering the constraints from DM direct detection experiment, DM indirect detection experiment, and DM relic density, we find that the allowed parameter space of the scalar DM model will be completely excluded for the former cosmological observations, while it will increase for the latter ones. Those two cosmological observations lead to an almost paradoxical conclusion. Therefore, one could expect more stringent constraints on the WMIP DM models, with the accumulation of more accurate cosmological observations in the near future.

astro-ph.CO↗

arXiv2017

Mass Dependence of Higgs Production at Large Transverse Momentum through a Bottom Quark Loop

In the production of the Higgs through a bottom-quark loop, the transverse momentum distribution of the Higgs at large $P_T$ is complicated by its dependence on two other important scales: the bottom quark mass $m_b$ and the Higgs mass $m_H$. A strategy for simplifying the calculation of the cross section at large $P_T$ is to calculate only the leading terms in its expansion in $m_b^2/P_T^2$. In this paper, we consider the bottom-quark-loop contribution to the parton process $q\bar{q}\to H+g$ at leading order in $α_s$. We show that the leading power of $1/P_T^2$ can be expressed in the form of a factorization formula that separates the large scale $P_T$ from the scale of the masses. All the dependence on $m_b$ and $m_H$ can be factorized into a distribution amplitude for $b \bar b$ in the Higgs, a distribution amplitude for $b \bar b$ in a real gluon, and an endpoint contribution. The factorization formula can be used to organize the calculation of the leading terms in the expansion in $m_b^2/P_T^2$ so that every calculation involves at most two scales.

hep-ph↗

arXiv2017

Mass Dependence of Higgs Production at Large Transverse Momentum

The transverse momentum distribution of the Higgs at large $P_T$ is complicated by its dependence on three important energy scales: $P_T$, the top quark mass $m_t$, and the Higgs mass $m_H$. A strategy for simplifying the calculation of the cross section at large $P_T$ is to calculate only the leading terms in its expansion in $m_t^2/P_T^2$ and/or $m_H^2/P_T^2$. The expansion of the cross section in inverse powers of $P_T$ is complicated by logarithms of $P_T$ and by mass singularities. In this paper, we consider the top-quark loop contribution to the subprocess $q\bar{q}\to H+g$ at leading order in $α_s$. We show that the leading power of $1/P_T^2$ can be expressed in the form of a factorization formula that separates the large scale $P_T$ from the scale of the masses. All the dependence on $m_t$ and $m_H$ can be factorized into a distribution amplitude for $t \bar t$ in the Higgs, a distribution amplitude for $t \bar t$ in a real gluon, and an endpoint contribution. The factorization formula can be used to simplify calculations of the $P_T$ distribution at large $P_T$ to next-to-leading order in $α_s$.

hep-ph↗

arXiv2014

Hadronic production of $Ξ_{cc}$ at a fixed-target experiment at the LHC

In the paper, we present a detailed discussion on the $Ξ_{cc}$ production at a fixed target experiment at the LHC (After@LHC). The doubly charmed baryon $Ξ_{cc}$ is produced via the channel, ${\rm Proton} + {\rm Proton}\toΞ_{cc}+X$. In estimating its hadroproduction, we discuss three dominant subprocesses, e.g. $g+g\to Ξ_{cc} +\bar{c} +\bar{c}$, $g+c\to Ξ_{cc}+\bar{c}$ and $c+c\to Ξ_{cc}+g$. During the production, it shall first generate a binding diquark and then form the $Ξ_{cc}$ baryon by grabbing soft light-quarks or gluons. We observe that both the two diquark configurations $(cc)[^3S_1]_{\bf\bar 3}$ and $(cc)[^1S_0]_{\bf 6}$ can have sizable contributions to the $Ξ_{cc}$ production. Large number of $Ξ_{cc}$ events can be generated at the After@LHC, whose total production cross section is larger than that of the SELEX experiment by about thirty-five times. It may also possible to study the properties of $Ξ_{bc}$ at the After@LHC. More specifically, we shall have about $8.3 \times 10^6$ $Ξ_{cc}$ events/year and $1.8 \times 10^4$ $Ξ_{bc}$ events/year when its integrated luminosity approaches to $2$ fb$^{-1}$/year. Thus, in addition to SELEX and LHC, the After@LHC shall provide another useful platform for studying the baryon properties.

hep-ph↗

arXiv2013

Revisiting the $B^{(*)}_s$-Meson Production at the Hadronic Colliders

The production of heavy-flavored hadron at the hadronic colliders provides a challenging opportunity to test the validity of pQCD predictions. There are two mechanisms for the $B^{(*)}_s$ hadroproduction, i.e. the gluon-gluon fusion mechanism via the subprocess $g+g\rightarrow B^{(*)}_s+b+\bar{s}$ and the extrinsic heavy quark mechanism via the subprocesses $g+\bar{b}\to B^{(*)}_s +\bar{s}$ and $g+s\to B^{(*)}_s +b$, both of which shall have sizable contributions in proper kinematic region. Different from the fixed-flavor-number scheme (FFNS) previously adopted in the literature, we study the $B^{(*)}_s$ hadroproduction under the general-mass variable-flavor-number scheme (GM-VFNS), in which we can consistently deal with the double counting problem from the above two mechanisms. Properties for the $B^{(*)}_s$ hadroproduction are discussed. To be useful reference, a comparative study of FFNS and GM-VFNS is presented. Both of which can provide reasonable estimations for the $B^{(*)}_s$ hadroproduction. At the Tevatron, the difference between these two schemes is small, however such difference is obvious at the LHC. The forthcoming more precise data on LHC shall provide a good chance to check which scheme is more appropriate to deal with the $B^{(*)}_s$-meson production and to further study the heavy quark components in hadrons.

hep-ph↗

arXiv2013

Further Study on the Doubly Heavy Baryon Production around the $Z^0$ Peak at A High Luminosity $e^+ e^-$ Collider

The doubly heavy baryon $Ξ_{QQ^{\prime}}$ ($Q^{(\prime)}$ = $b$ or $c$) is different from the ordinary baryons. The production of the doubly heavy baryon can provide valuable insight on how the colored $(QQ^{\prime})$-diquark can be transformed into the color-singlet baryon. As a sequential work of Ref.[2], we make a further study on the doubly heavy baryon production through the $e^+ e^-$ annihilation channel, $e^{+} + e^{-}\rightarrowγ/Z^0 \rightarrow Ξ_{QQ^{\prime}} +\bar{Q} +\bar{Q^{\prime}}$, within the nonrelativistic QCD framework. In addition to the total cross sections, we present the baryon transverse momentum and the rapidity distributions for all these channels. Typical baryon transverse momentum and rapidity cuts are adopted to show the properties of these distributions clearly. At a $e^+ e^-$ collider that runs around the $Z^0$-boson mass with a high luminosity up to ${\cal L} = 10^{34-36}{\rm cm}^{-2} {\rm s}^{-1}$, in comparison to the Belle and BABAR experiments, it is found that sizable $Ξ_{cc}$, $Ξ_{bc}$ and $Ξ_{bb}$ events can be produced even after performing baryon's transverse momentum and rapidity cuts due to $Z^0$-boson resonance effect.

hep-ph↗

arXiv2012

Excited Heavy Quarkonium Production at the LHC through $W$-Boson Decays

Sizable amount of heavy-quarkonium events can be produced through $W$-boson decays at the LHC. Such channels will provide a suitable platform to study the heavy-quarkonium properties. The "improved trace technology", which disposes the amplitude ${\cal M}$ at the amplitude-level, is helpful for deriving compact analytical results for complex processes. As an important new application, in addition to the production of the lower-level Fock states $|(Q\bar{Q'})[1S]>$ and $|(Q\bar{Q'})[1P]>$, we make a further study on the production of higher-excited $|(Q\bar{Q'})>$-quarkonium Fock states $|(Q\bar{Q'})[2S]>$, $|(Q\bar{Q'})[3S]>$ and $|(Q\bar{Q'})[2P]>$. Here $|(Q\bar{Q'})>$ stands for the $|(c\bar{c})>$-charmonium, $|(c\bar{b})>$-quarkonium and $|(b\bar{b})>$-bottomonium respectively. We show that sizable amount of events for those higher-excited states can also be produced at the LHC. Therefore, we need to take them into consideration for a sound estimation.

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