arXiv subjects

Chao-Qiang Geng

Publications and source records attributed to Chao-Qiang Geng.

At least 37 records · Page 2Linked to original sources

arXiv2025

Two-body charmed baryon nonleptonic weak decays with decuplet baryon involving SU(3) breaking effects

We study the singly charmed baryon two-body decays of $\mathbf{B}_c \rightarrow \mathbf{B}_D P$ under $SU(3)_{F}$ flavor symmetry, where ${\bf B}_{c}$ refers to anti-triplet singly charmed baryons, and ${\bf B}_{D}$ and $P$ denote decuplet baryons and pseudoscalar mesons, respectively. Compared to the literature, we adopt a concise and reasonable treatment of the $SU(3)$ flavor symmetry breaking, by considering the final-state mass dependence of partial waves. With 4 real parameters in total and 9 experimental data points, we achieve a minimal $χ^2/\text{d.o.f.} $ value of $ 1.46$, providing a satisfactory explanation to the experiment results. We evaluate the branching ratios and Lee-Yang parameters suggesting the absence of the strong phase in $\mathbf{B}_c \rightarrow \mathbf{B}_D P$, along with an unusual positive decay asymmetry $α\,(Ξ_{c}^{0}\rightarrow Ω^{-}K^{+})$. The predicted results of large $SU(3)_{F}$ breaking effects in $\mathbf{B}_c \rightarrow \mathbf{B}_D P$ can be verified in the further research by the experiments at BESIII, Belle-II and LHCb.

hep-ph↗

arXiv2024

Hidden strangeness in meson weak decays to baryon pair

Our study focuses on the weak decay of $ D_s^+ \to p \overline{n} $, which is the only possible two-body baryonic decay in the $ D $ meson system. An analysis using perturbative quantum chromodynamics (pQCD) is challenging in this decay due to the small amount of energy released. In particular, naive factorization, suppressed by the light quark masses, results in a minor contribution to this channel. In the framework of final state interactions, the hidden strangeness in the intermediate state naturally avoids this chiral suppression from light quark masses. The branching fraction is predicted to be $ {\cal B}(D_s^+ \to p\overline{n}) = (1.43 \pm 0.10) \times 10^{-3} $, in agreement with the experimental value of $ (1.22 \pm 0.11) \times 10^{-3} $. We also analyze the decays of $ B $ mesons into two charmed baryons involving annihilation-type topological diagrams. In these decays, we conduct a joint analysis of naive factorization and final state interactions. Using the experimental upper bound of $ {\cal B}(B_s^0 \to Λ_c^+ \overlineΛ_c^-) < 8 \times 10^{-5} $, we set a constraint on the coupling constant $ g_{D^+ Λ_c^+ n} < 7.5 $. Final state interactions lead to a prediction of the decay parameter $ γ(B_s^0 \to Λ_c^+ \overlineΛ_c^-) > 0.8 $, whereas pQCD predicts it to be negative. We propose future measurements of $ B^0 \to Ξ_c^+ \overlineΞ_c^- $, predicting a significant $ SU(3)_F $ breaking effect with $ \frac{{\cal B}(B^0 \to Ξ_c^+ \overlineΞ_c^-)}{{\cal B}(B_s^0 \to Λ_c^+ \overlineΛ_c^-)} = 1.4\% $, contrary to the naive estimate of $ 5.3\% $. We strongly recommend future measurements.

hep-ph↗

arXiv2024

Categorizing $SU(3)_f$ representations of scalar mesons by $J/ψ$ decays

The scalar mesons are established for a long time, but their nature is still an open question. In this paper, we investigate the potential of categorizing their $SU(3)_f$ representations via $J/ψ\to SV$ and $γS$, offering a criterion that may illuminate this issue. Here, $S$ ($V$) denotes scalar (vector) mesons. Using the $SU(3)_f$ symmetry with the current data, we find that $f_0(500)$ and $f_0(980)$ are mostly made of singlet and octet $SU(3)_f$ representations, respectively, with the singlet-octet mixing angle of $θ= (82.9\pm4.4)^{\circ}$. This conclusion is consistent with the caculations of the quark-antiquark ($q\bar{q}$) hypothesis. For the scalar mesons in the range of 1-2 GeV, we discuss the mixings between $q\bar{q}$ and glueballs. Our numerical results suggest that $f_0(1710)$ is likely composed of the scalar glueball. We urge our experimental colleagues to measure $J/ψ\to ρa_0(980,\ 1450,\ 1710), $ $ K^*(892)^{\pm} K^*(700,\ 1430,\ 1950)^{\mp}$ and $ωf_0(500)$, which provide useful information in the $SU(3)_f$ analysis.

hep-ph↗

arXiv2024

Thermodynamic of the $f(Q)$ universe

We investigate thermodynamics of apparent horizon in the $f(Q)$ universe with trivial and nontrivial connections. We first explore the perspectives of the first law, generalized second law and $P-V$ phase transition with trivial connection. We show that the lowest-order correction of entropy has the same form as that in loop quantum gravity, and the critical exponents of the phase transition caused by the lowest-order correction are consistent with those in mean field theory. We then examine the thermodynamic implication of nontrivial connections. We find that nontrivial connections in the $f(Q)$ universe imply non-equilibrium states from the perspective of thermodynamics.

gr-qc↗

arXiv2024

New Signature of low mass $Z^\prime$ in $J/ψ$ decays

We explore a new approach to search for a low-mass $Z^{\prime}$ particle through $J/ψ$ decays by identifying its existence through parity-violating phenomena in the isospin-violating final states of $Λ\overlineΣ^{0}$ and the corresponding charge conjugated states of $\overlineΛΣ^{0}$. Our investigation centers on a generation-independent and leptophobic $Z^{\prime}$ with its mass below 10 GeV. Given the present experimental conditions at the Beijing Spectrometer III~(BESIII) and the anticipated opportunities at the Super Tau Charm Factory~(STCF), we conduct Monte-Carlo simulations to predict possible events at both facilities. Notably, we foresee a substantial enhancement in the precision of the lower limit estimation of $α_{\text{NP}}$ as well as a reduction in statistical uncertainty with upcoming STCF experiments. Furthermore, it is essential to highlight that a null result in the measurement of $α_{\text{NP}}$ would impose stringent constraints, requiring the $Z^{\prime}-q-q$ couplings to be on the order of $10^{-2}$.

hep-ph↗

arXiv2024

Effects of stimulated emission and superradiant growth of non-spherical axion cluster

We explore the stimulated emission of photons in non-spherical axion clusters with or without the axion source from the superradiance of a rotating black hole (BH). In particular, we focus on the cluster with the initial axion distribution in the $(l,m)=(1,1)$ mode which mimics the shape of an axion cloud induced by the BH superradiance. After establishing the hierarchy of Boltzmann equations governing a general non-spherical axion-photon system, we examine the evolution of photon and axion distributions in the cluster and possible stimulated emission signals. In the case without the axion source, the resultant signal would be a single photon pulse. As for the system with the BH superradiance as the axion source, multiple pulses are predicted. We also show that, for the latter case, the combined effects of stimulated emissions and the axion production from the BH superradiance could reach a balance where the axion cluster becomes uniformly and spherically distributed. Due to the energy and temporal characteristics of the obtained pulses, we demonstrate that the stimulated emissions from the axion cluster with axions sourced by the BH superradiance provide a candidate explanation to the observed fast radio bursts.

hep-ph↗

arXiv2024

Nonleptonic three-body charmed baryon weak decays with H(15)

We study the nonleptonic three-body charmed baryon weak decays of $\mathbf{B}_{c}\rightarrow\mathbf{B}_{n}PP^{\prime}$ under the $SU(3)_{F}$ flavor symmetry, where $\mathbf{B}_{c}$ denotes the anti-triplet charmed baryon, comprising $(Ξ^{0}_{c},-Ξ^{+}_{c},Λ^{+}_{c})$, and $\mathbf{B}_{n}$ and $P(P^{\prime})$ represent octet baryon and pseudoscalar meson states, respectively. In addition to 12 parameters from the contributions of the color-antisymmetric part of the effective Hamiltonian, denoted as $H(\bar{\mathbf{6}})$, there are 4 parameters from the color-symmetric one, $H(\mathbf{15})$, which were not included in the previous study. With 16 parameters in total and 28 experimental data points, we obtain the minimal $χ^2$ over degree of freedom of $χ^{2}/d.o.f=1.5$, which is a great improvement comparing to that without $H(\mathbf{15})$. With the better fitting values, we evaluate the branching ratios and up-down asymmetries of $\mathbf{B}_{c}\rightarrow\mathbf{B}_{n}PP^{\prime}$, which present some interesting results such as $\mathcal{B}\,(Λ^{+}_{c}\rightarrow(Ξ(1690)^{0}\rightarrowΣ^{+}K^{-})\,K^{+})\equiv(1.5\pm0.4)\times10^{-3}$ and potential $SU(3)$ breaking effects in $Ξ^{+}_{c}\rightarrow pπ^{+}K^{-}$ and $Λ^{+}_{c}\rightarrow Σ^{+}π^{-}K^{+}$ to be verified by the experiments at BESIII, Belle-II and LHCb.

hep-ph↗

arXiv2024

Complete determination of $SU(3)_F$ amplitudes and strong phase in $Λ_c^+ \to Ξ^0 K^+$

The BESIII collaboration has recently reported the first time measurement of the decay asymmetry $α(Λ_c^+ \to Ξ^0 K^+) = 0.01 \pm 0.16(stat.) \pm 0.03(syst.)$ and also a sizable phase shift of $δ_P-δ_S = -1.55 \pm 0.25$ or $1.59\pm 0.25$ between S- and P-wave amplitudes. This implies significant strong phase shifts in the decay amplitudes. The strong phases indicate the existence of rescattering or loop effects, which are challenging to calculate due to non-perturbative effects. By employing the flavor $SU(3)_F$ symmetry and applying the Körner-Pati-Woo theorem to reduce the number of parameters, we find that the current data already allow us to obtain, for the first time, model-independent decay amplitudes and their strong phases. The establishment of the existence of sizable strong phases opens a window for future investigations into CP violation. In our fit, a notable discrepancy emerges in the branching ratio of $Ξ_c^0 \to Ξ^- π^+$. The direct relationship between $Γ(Λ_c^+ \to Λe^+ν_e)$ and $Γ(Ξ_c^0 \to Ξ^- e^+ν_e)$, along with newly discovered $SU(3)_F$ relations, collectively suggests an underestimation of $\mathcal{B}(Ξ_c^0 \to Ξ^- π^+)$ in experimental findings.

hep-ph↗

arXiv2023

Gravitational wave in symmetric teleparallel gravity with different connections

We investigate the cosmological perturbations around all three branches of spatially flat universe with different connections in symmetric teleparallel gravity. The model we consider can cover both the case of f(Q) model and that of the non-minimal coupling between a scalar field and the non-metricity scalar. We focus on analyzing and comparing the propagation behavior and stability of the tensorial and non-tensorial gravitational waves on spatially flat universe with different connections.

gr-qc↗

arXiv2023

Isospin violating decays of vector charmonia

We study the isospin violating decays of vector charmonia to $Λ\overlineΣ^0$ and its charge conjugate. They are dominated by the single photon annihilation and can be evaluated reliably with timelike form factors. We utilize the quark-pair creation model, which is valid for the OZI suppressed decays, to evaluate the form factors. We obtain the branching fractions of ${\cal B}(J/ψ\toΛ\overlineΣ^0+c.c.)=(2.4\pm0.4)\times10^{-5}$ and ${\cal B}(ψ(2S)\toΛ\overlineΣ^0+c.c.)=(3.0\pm0.5)\times10^{-6}$, which are compatible with the measurements by the BESIII collaborations, respectively. The decay asymmetries are found to be $α_{J/ψ}=0.314$ and $α_{ψ(2S)}=0.461$, which can be examined at BESIII in the foreseeable future.

hep-ph↗

arXiv2023

$W$-boson Mass Anomaly from High-Dimensional Scalar Multiplets

In light of the recently discovered $W$-boson mass anomaly by the CDF Collaboration, we discuss two distinct mechanisms that could possibly explain this anomaly through the introduction of high-dimensional $SU(2)_L$ scalar multiplets. The first mechanism is the tree-level $W$-boson mass correction induced by the vacuum expectation values of one or more $SU(2)_L$ scalar multiplets with odd dimensions of $n\geq 3$ and zero hypercharge of $Y=0$ in order to avoid the strong constraint from measurements of the $Z$-boson mass. The second mechanism is to consider the one-loop level $W$-boson mass correction from a complex multiplet. In particular, we focus on the case with an additional scalar octuplet with $Y=7/2$. As a result, we find that both mechanisms can explain the $W$-boson mass anomaly without violating any other theoretical or experimental constraints.

hep-ph↗

arXiv2023

Cosmic Birefringence from Neutrino and Dark Matter Asymmetries

In light of the recent measurement of the nonzero Cosmic Microwave Background (CMB) polarization rotation angle from the Planck 2018 data, we explore the possibility that such a cosmic birefringence effect is induced by coupling a fermionic current with photons via a Chern-Simons-like term. We begin our discussion by rederiving the general formulae of the cosmic birefringence angle with correcting a mistake in the previous study. We then identify the fermions in the current as the left-handed electron neutrinos and asymmetric dark matter (ADM) particles, since the rotation angle is sourced by the number density difference between particles and antiparticles. For the electron neutrino case, with the value of the degeneracy parameter $ξ_{ν_e}$ recently measured by the EMPRESS survey, we find a large parameter space which can explain the CMB photon polarization rotations. On the other hand, for the ADM solution, we consider two benchmark cases with $M_χ= 5$~GeV and 5~keV. The former is the natural value of the ADM mass if the observed ADM and baryon asymmetry in the Universe are produced by the same mechanism, while the latter provides a warm DM candidate. In addition, we explore the experimental constraints from the CMB power spectra and the DM direct detections.

astro-ph.CO↗

arXiv2023

Anatomy of $Λ_c^+$ semileptonic decays

We present a systematic study of $Λ_c^+ \to {\cal B}_q \ell^+ ν_\ell $ with ${\cal B}_q = (Λ, n)$ and $\ell =( e, μ)$, examining all the possible decay observables based on the homogeneous bag model (HBM) and lattice QCD (LQCD). With the HBM, we find that the branching fractions and polarization asymmetries of the daughter baryon $Λ$ are ${\cal B}(Λ_c^+ \to Λe^+ ν_e, Λμ^+ ν_μ, n \ell ^+ ν_\ell ) = (3.78 \pm 0.25, 3.67\pm 0.23, 0.40\pm 0.04 )\%$ and $α_Λ(Λ_c^+ \to Λe^+ ν_e,Λμ^+ ν_μ) =(-82.6,-82.3)\%$, respectively. From the LQCD, we obtain that $α_Λ(Λ_c^+ \to Λe^+ ν_e, μ^+ ν_μ) = (-87.4\pm 1.0,-87.2\pm 1.0)\%$. We also explore the time-reversal asymmetries due to new physics beyond the standard model. All our results are consistent with the current experimental data, while some of them are accessible to the experiments at BESIII and Belle II.

hep-ph↗

arXiv2023

CP asymmetries in $B$ meson two-body baryonic decays

We study the CP-odd and CP-even observables of the $B$ mesons decaying into a baryon and antibaryon. We estimate these observables through the $^3P_0$ model and chiral selection rule. The decay branching ratios of $ B^+ \to p \overlineΛ$ and $ B^0 \to p \overline{p}$ are calculated to be $2.31 \times 10^{-7}$ and $1.27 \times 10^{ -8} $, which are consistent with the current experiments, respectively. The effects of the $B-\overline{B}$ oscillations are considered, which largely suppress the direct CP asymmetries in the $B_s^0$ decays. We suggest the experiments to visit $B_s^0 \to Λ(\to p π^-) \overlineΛ (\to \overline{ p} π^+) $, where the time-averaged CP-odd observables are estimated to be large. The direct CP asymmetries of $B^+ \to p \overlineΛ$ and $B^0 \to p\overline{p}$ are found to be $26.2\%$ and $-3.1\%$ for a positive strong phase and $-36.9\%$ and $4.2\%$ for a negative strong phase, respectively.

hep-ph↗

arXiv2023

FCNC processes of charmed hadrons with invisible scalar

We study the invisible scalar of $S$ in charmed meson and baryon decays with flavor-changing neutral currents (FCNCs) based on the model-independent effective Lagrangian between the quarks and invisible scalar. From the bounds of the coupling constants extracted from the recent BES III experiment on the decay of $D^{0}\toπ^{0}\barνν$, we predict that the decay branching ratios of $D^{+}\toπ^{+}S$, $D_s^+\to K^+S$, $Λ_c\to pS$, $Ξ_c^{0(+)}\to Σ^{0(+)}S$, and $Ξ_c^0\toΛS$ can be as large as $10.6,~2.53,~2.39,~0.963,~5.77$, and $2.92\times10^{-4}$ with $m_{_S}\approx 1.1~{\rm GeV}$, respectively. Some of these decay modes are accessible to the ongoing experiments, such as BES III, LHCb and Belle II, as well as the future ones, such as FCC-ee.

hep-ph↗

arXiv2023

Heavy quark symmetry of $Λ_b^0$ decays in quark models

We study the heavy quark symmetry with the homogeneous bag model (HBM) and light-front quark model (LFQM) based on the decays of $Λ_b^0\toΛ_c^+\ell^-\overlineν_\ell~(\ell=e,μ,τ)$. In particular, we calculate various parameters in the heavy quark expansions, including the Isgur-Wise functions and their first order corrections. The parameters in the HBM are fitted from the mass spectra, while the ones in the LFQM are tightly constrained by the heavy quark symmetry, granting the predictive power of our results. We explicitly obtain that ${\cal B}(Λ_b^0\toΛ_c^+e^-\overlineν_e)=(5.69\pm 0.58, 5.35\pm 0.50)$, ${\cal B}(Λ_b^0\toΛ_c^+μ^-\overlineν_μ)=(5.67\pm 0.58 $, $5.33\pm 0.49)$, and $Γ(Λ_b^0\toΛ_c^+τ^-\overlineν_τ)/Γ(Λ_b^0\toΛ_c^+μ^-\overlineν_μ)=(0.3243\pm 0.0126$, $ 0.3506\pm 0.0046)$ for the numerical values of (HBM, LFQM). Our results of the branching fractions in both models agree well with the experimental data and lattice QCD calculations. In addition, we find that the hard gluon corrections decrease the branching fractions around $10\%$.

hep-ph↗

arXiv2023

$W$-Boson Mass Anomaly from a General $SU(2)_{L}$ Scalar Multiplet

We explain the $W$-boson mass anomaly by introducing an $SU(2)_L$ scalar multiplet with general isospin and hypercharge in the case without its vacuum expectation value. It is shown that the dominant contribution from the scalar multiplet to the $W$-boson mass arises at one-loop level, which can be expressed in terms of the electroweak (EW) oblique parameters $T$ and $S$ at leading order. We firstly rederive the general formulae of $T$ and $S$ induced by a scalar multiplet of EW charges, confirming the results in the literature. We then study several specific examples of great phenomenological interest by applying these general expressions. As a result, it is found that the model with a scalar multiplet in an $SU(2)_L$ real representation with $Y=0$ cannot generate the required $M_W$ correction since it leads to vanishing values of $T$ and $S$. On the other hand, the cases with scalars in a complex representation under $SU(2)_L$ with a general hypercharge can explain the $M_W$ excess observed by CDF-\uppercase\expandafter{\romannumeral2} due to nonzero $T$ and $S$. We further take into account of the strong constraints from the perturbativity and the EW global fit of the precision data, and vary the isospin representation and hypercharge of the additional scalar multiplet, in order to assess the extent of the model to solve the $W$-boson mass anomaly. It turns out that these constraints play important roles in setting limits on the model parameter space. We also briefly describe the collider signatures of the extra scalar multiplet, especially when it contains long-lived heavy highly charged states.

hep-ph↗

arXiv2023

Muon $g-2$ Anomaly from a Massive Spin-2 Particle

We investigate the possibility to interpret the muon $g-2$ anomaly in terms of a massive spin-2 particle, $G$, which can be identified as the first Kaluza-Klein graviton in the generalized Randall-Sundrum model. In particular, we obtain the leading-order contributions to the muon $g-2$ by calculating the relevant one-loop Feynman diagrams induced by $G$. The analytic expression is shown to keep the gauge invariance of the quantum electrodynamics and to be consistent with the expected UV divergence structure. Moreover, we impose the theoretical bounds from the perturbativity and the experimental constraints from LHC and LEP-II on our model. Especially, we derive novel perturbativity constraints on nonrenormalizable operators related to $G$, which are the natural generalization of the counterpart for the renormalizable operators. As a result, we show that there exists a substantial parameter space, which can accommodate the muon $g-2$ anomaly allowed by all constraints. Finally, we also make comments on the possible explanation of the electron $g-2$ anomalies with the massive spin-2 particle.

hep-ph↗