arXiv subjects

Ishtiaq Ahmed

Publications and source records attributed to Ishtiaq Ahmed.

At least 19 recordsLinked to original sources

arXiv2026

A Phenomenological Study of Semileptonic $B^+$ and $B_s^0$ Decays into Axial-Vector Mesons $\big(D_1(2420),\, D_1^\prime(2430),\, D_{s1}(2460),\, \text{and } D_{s1}^\prime(2536)\big)$ within the Standard Model

We study semileptonic $B$ meson decays $B^+ \to D_1^{(\prime)}\ell^+ν_\ell$ and $B_s^0 \to D_{s1}^{-(\prime)}\ell^+ν_\ell$, where $\ell=μ,τ$. The final state axial vector mesons are treated as mixtures of the heavy quark basis states with light degree of freedom angular momenta $j_\ell=1/2$ and $j_\ell=3/2$, parametrized by the mixing angle $θ_{D_1}$. Using form factors obtained in the covariant light front quark model, we analyze the dependence of various observables on $θ_{D_1}$ such as polarized and unpolarized branching ratios, the lepton forward-backward asymmetry, the longitudinal polarization fraction, and the lepton flavor universality ratios. In addition, we also discuss correlations among different observables. We study these observables in the experimentally motivated mixing angle regions as well as over a wider range of $θ_{D_1}$. Our results show that branching ratios and other observables are sensitive to the axial-vector mixing structure. These predictions provide useful Standard Model benchmarks for future measurements of semileptonic $B_{(s)}$ decays into orbitally excited mesons and may help to clarify the long standing $1/2$ vs. $3/2$ puzzle through semileptonic $B$ decays.

hep-ph↗

arXiv2026

Hyperfine Mixing and Final-Spin Redistribution in Inclusive $Ξ_{bc}\to H_{cc}+X$

In this work, we study the effect of hyperfine mixing on the inclusive weak transition $Ξ_{bc}\to H_{cc}+X$, which has been proposed as a useful channel for searching for beauty-charmed baryons. Starting from the inclusive heavy-diquark framework, we include mixing between the scalar and axial-vector $bc$ configurations and decompose the final doubly charmed system into the $J_f=1/2$ and $J_f=3/2$ spin sectors. Within a minimal scalar-to-axial transition model, and for a benchmark scalar-channel normalization of order unity at zero recoil, we find that the interference between the scalar and axial components is large in the separate spin sectors but cancels after summing over the two members of the adopted ground-state $ccq$ spin multiplet, $Γ_{AS}^{1/2}=-Γ_{AS}^{3/2}$. Consequently, the spin-summed inclusive rate is less sensitive to hyperfine mixing than the direct ground-state contribution, provided feed-down from the spin-excited $Ξ_{cc}^{*}$ partner is experimentally unresolved. For a scalar-channel normalization of order unity, the direct contribution can be strongly spin selective: $Ξ_{bc}^{(1)}$ dominantly feeds the $J_f=1/2$ $Ξ_{cc}$ channel, whereas $Ξ_{bc}^{(2)}$ dominantly feeds the $J_f=3/2$ $Ξ_{cc}^{*}$ sector. We test this pattern for several convention-matched literature admixtures and for a separately labeled decay-interference diagnostic angle, together with the dependence on the scalar-to-axial normalization and recoil-shape choice. The cancellation of the spin-summed interference is a consequence of baryon spin recoupling within the spectator and common-multiplet assumptions, whereas the magnitude of the spin selectivity is conditional on the magnitude and relative phase of the scalar-to-axial transition.

hep-ph↗

arXiv2026

Three Predictions for Partonic Energy Loss from Light to Heavy Ion Collisions

In July 2025 the Large Hadron Collider (LHC) collided $^{16}$O$^{16}$O and $^{20}$Ne$^{20}$Ne isotopes in a quest to understand the physics of ultrarelativistic light ion collisions. One of the key motivations for this run is to discover partonic energy loss in systems with a small quark-gluon plasma (QGP). In this letter we combine a BDMPS-Z based model, a weighted path based energy loss prescription, and JEWEL together with two realistic geometries of the $^{16}$O and $^{20}$Ne isotopes. The different sizes of the ions affect the energy loss in characteristically different ways depending on the model.

nucl-th↗

arXiv2026

SLogic: Subgraph-Informed Logical Rule Learning for Knowledge Graph Completion

Logical rule-based methods offer an interpretable approach to knowledge graph completion (KGC) by capturing compositional relationships in the form of human-readable inference rules. While existing logical rule-based methods learn rule confidence scores, they typically assign a global weight to each rule schema, applied uniformly across the graph. This is a significant limitation, as a rule's importance often varies depending on the specific query instance. To address this, we introduce SLogic (Subgraph-Informed Logical Rule learning), a novel framework that assigns query-dependent scores to logical rules. The core of SLogic is a context-aware scoring function. This framework is in line with the specificity principle in commonsense reasoning. This function determines the importance of a rule by analyzing the subgraph locally defined by the query's head entity, thereby enabling a differentiated weighting of rules specific to their local query contexts. Extensive experiments on benchmark datasets show that SLogic achieves competitive performance among rule-based methods. It also generates query-dependent, human-readable logical rules that serve as explicit explanations for its inferences.

cs.LG↗

arXiv2026

The effects of polarization on the observables in the decay $Ξ_{cc}^{++} \rightarrow Ξ_{c}^{+} \bar{\ell}ν_{\ell}$

We investigate the effects of polarization on several physical observables in the semileptonic decay $Ξ_{cc}^{++} \rightarrow Ξ_c^{+} \bar{\ell}ν_{\ell}$. We analyze the polarization effects of the particles involved in the decay, namely $Ξ_{cc}^{++}$, $Ξ_c^{+}$, and the charged muon $\ell$. Using the form factors obtained from QCD sum rules, we compute the $q^{2}$-dependent observables including the differential branching ratio, forward-backward asymmetry, and polarization asymmetries for both longitudinal and transverse polarization states. We also define and examine several polarization ratios and discuss correlations among different observables. In addition, we evaluate the lepton flavor universality ratio defined as $\mathcal{R}_{Ξ_c^+}(μ/e) \equiv \mathcal{D}(Ξ_{cc}^{++}\to Ξ_c^+μ^+ν_μ)/\mathcal{D}(Ξ_{cc}^{++}\to Ξ_c^+e^+ν_e)$ and analyze its behavior over the available dynamical range. Our results show that these observables are quite sensitive to polarization effects, and can provide suitable probes for testing Standard Model predictions.

hep-ph↗

arXiv2026

Search for New Physics through the Observables of Semileptonic $B_{c}^+\to D^{\ast+}\ell^{+}\ell^{-}$ Decay

Motivated by the current flavor anomalies and the comparatively less explored nature of the $b\to d$ sector, we present a model-independent study of the rare semileptonic $B_c^{+}\to D^{\ast+}\ell^{+}\ell^{-}$ ($\ell=μ,τ$) decay, to investigate its sensitivity to New Physics effects. The analysis incorporates penguin-box contributions, long-distance resonance effects, and the sizable weak-annihilation amplitudes. Using the $B_c\to D^\ast$ transition form factors calculated in the covariant confined quark model and the weak-annihilation form factors obtained within the Bethe--Salpeter approach, we analyze the differential branching fraction, forward-backward asymmetry, longitudinal helicity fraction, and a comprehensive set of normalized angular observables in several one- and two-dimensional New Physics scenarios and compare our results with the Standard Model predictions. Notably, the branching fraction, forward-backward asymmetry, and the normalized angular coefficients such as, $\langle I_{2c}\rangle$, $\langle I_{3}\rangle$, $\langle I_{5}\rangle$, and $\langle I_{6s} \rangle$, show clear sensitivity to New Physics effects. Our results indicate that the decay $B_c^{+}\to D^{\ast+}\ell^{+}\ell^{-}$ serves as a complementary probe of the flavor structure of New Physics and can therefore be investigated in future measurements at LHCb and other high-luminosity flavor experiments.

hep-ph↗

arXiv2026

Lepton polarization dependent angular observables and the polarization asymmetries in the four-fold $Λ_b \rightarrow Λ(\rightarrow N π) \ell^+\ell^-$ decay

The rare decays mediated by flavor-changing neutral current processes, such as $b \to s \ell^{+}\ell^{-}$, provide powerful probes of the Standard Model and potential windows into new physics. Particularly, the angular observables in these exclusive decays are valuable because of their sensitivity to short-distance dynamics and their reduced dependence on hadronic uncertainties, which mainly arise from form factors. In this work, we analyze the $Λ_b \to Λ(\to Nπ)\ell^{+}\ell^{-}$ (with $Nπ=\{pπ^-,nπ^0\}$) decay with polarized final-state lepton and derive the corresponding four-fold differential decay distributions. For the longitudinal, normal, and transverse polarization states, we systematically identify the additional angular coefficients that emerge relative to the unpolarized case. We find that the longitudinal polarization preserves the structure of the unpolarized distribution, while the normal and transverse polarizations introduce some new additional angular coefficients. The analytical expressions of all polarized and unpolarized angular coefficients are explicitly derived in terms of the helicity and transversity amplitudes. To compare the variation in the polarized and unpolarized angular observables, we have plotted them against the square of the momentum transfer $q^2$. Additionally, the Standard Model predictions of the polarization asymmetry observables are provided and their sensitivity to new physics is explored under different new physics scenarios. The obtained results, in the current study, for longitudinal and transverse polarization cases, provide a baseline for the lepton polarization dependent observables, which may serve as sensitive probes to test the Standard Model in these decays.

hep-ph↗

arXiv2026

Weak decay of the positronium ion

The positronium ion ($\mathrm{Ps}^-$), a coulombic three-body bound state of two electrons and a positron, predominantly decays via electron-positron annihilation into electromagnetic final states. While its radiative decay channels have been extensively studied, much less attention has been given to weak processes in this system. In this work, we investigate the rare decay $\mathrm{Ps}^- \to e^- ν_μ\barν_μ$, obtained by replacing the photon in $\mathrm{Ps}^- \to e^- γ$ with a virtual $Z$ boson. Treating the three-body process as an effective two-body transition, $\mathrm{Ps}^- \to e^- Z^*\left(\to ν_μ\barν_μ\right)$, we compute the decay rate by explicitly evaluating all spin configurations of the initial bound state and final particles. The result agrees with that obtained using the standard spin-summation formalism of quantum field theory. We find that the branching ratio is comparable to that of the weak decay of ortho-positronium, $\mathrm{o\text{-}Ps} \to γν\barν$.

hep-ph↗

arXiv2026

The Angular Observables of $Λ_b \to Λ_c(\to Λ^0 π^+) \, τ^-(\to π^- ν_τ)\, \barν_τ$ within the Paradigm of FCCC Anomalies

We present a global analysis of the current $B$-meson flavor anomalies and extend it to the baryonic sector through the decay $Λ_b^0 \to Λ_c^+(\to Λ^0 π^+) τ^-(\to π^- ν_τ)\barν_τ$. The lepton flavor universality ratios $R_{τ/(μ,e)}(D^{(*)})$, measured by BaBar, Belle, and LHCb, exhibit a combined $3.8σ$ deviation from Standard Model (SM) predictions. Using the latest HFLAV averages and $B_c$-lifetime constraints, $\mathcal{B}(B_c \to τν) < 60\%, 30\%, 10\%$, found new physics (NP) solutions to the cascade decay $Λ_b^0 \to Λ_c^+(\to Λ^0 π^+) τ^-(\to π^- ν_τ)\barν_τ$. The scenario $(C_{V_L},C_{S_R})$ emerges as the most favored NP solution, largest pull from the SM and insensitive to branching-ratio constraints; followed by $C_{V_L}$ case. We study the impact of NP operators on a complete set of angular observables on the five-fold $Λ_b$ decay using Lattice-QCD form factors and find that the scenarios $(\Re[C_{S_L}=4C_T],\Im[C_{S_L}=4C_T])$ and $(C_{S_L},C_{S_R})$ generate the largest deviations from the SM predictions. In particular, the observables $\mathcal{K}_{1c}$, $\mathcal{K}_{2ss}$, $\mathcal{K}_{2cc}$, and $\mathcal{K}_{4s}$ show the highest sensitivity to NP effects. The correlation analysis reveals the $(\Re[C_{S_L}=4C_T],\Im[C_{S_L}=4C_T])$ scenario exhibits inverse correlations among $\mathcal{K}_{1c}$ and $\mathcal{K}_{2ss,2cc,4s}$ and direct correlations between $\mathcal{K}_{2ss}$ and $\mathcal{K}_{2cc,4s}$, pointing to a possible CP-violating phase, while the $(C_{S_L},C_{S_R})$ scenario displays complementary behavior consistent with CP-conserving dynamics. These results establish baryonic semileptonic decays as a powerful and independent probe of the $R_{τ/(μ,e)}(D^{(*)})$ anomalies, with future measurements providing critical tests of the underlying NP structure.

hep-ph↗

arXiv2026

Weak Annihilation Contribution to Angular Observables in $B_{c}^+\to D^{\ast+}\ell^{+}\ell^{-}$ Decays

We analyze the rare semileptonic decays $B_{c}^+ \to D^{\ast+}(\to P_1 P_2)\ell^{+}\ell^{-}$, with $P_1 P_2 = D^+ π^0$ or $D^0 π^+$, and $\ell=μ, τ$. We focus on the impact of weak annihilation contributions alongside penguin, box, and long-distance effects. Using the effective Hamiltonian for $b \to d \ell^+ \ell^-$ transitions and $B_c \to D^{*}$ form factors from covariant confined quark model inputs, we compute the differential branching ratios, forward-backward asymmetry, longitudinal helicity fraction of the $D^{\ast}$, and various normalized angular coefficients. The results of the observables show that weak annihilation effects are sizable, particularly at low $q^2$, significantly modifying several observables and shifting zero-crossings. Resonance effects dominate at high $q^2$, restricting reliable analysis windows. We conclude that the inclusion of weak annihilation is essential for precise Standard Model predictions and for isolating possible New Physics effects in $B_c^+ \to D^{*+} \ell^+ \ell^-$ decays.

hep-ph↗

arXiv2025

Chirality structure of vector like new physics operators in charged current transitions

We investigate the cascade decay $B^{*0}_{s} \rightarrow D_s^-(\rightarrow τ^-\,\barν_τ)\,\ell^{+}\,ν_\ell$ induced by flavor changing charged currents in the context of the Standard Model and in vector-like couplings beyond the Standard Model. We employ the helicity amplitude formalism for analysis and highlight the role of new vector-like couplings in charged current interactions. We find, in particular, that while new left handed chiral-vector like interactions contribute to the branching ratio, they do not affect the forward-backward asymmetry, or the angular observables. On the other hand, the right handed chiral vector-like coupling in the case of this decay contributes to the branching ratio, forward-backward asymmetry and the angular observables. We confirm that this difference in behavior between the left and right handed NP couplings is a general feature of charged current processes with a vector meson going to a pseudoscalar at the tree level in effective weak theory by cross checking with the cascade decays $B^{*+}_c \rightarrow P(\rightarrow P'\,μ^+\,ν_μ)\,\ell^{+}\,ν_\ell$ where $P$ is $B_s^0$ ($D^0$) and $P'$ is $D_s^{*-}$ ($K^-$).

hep-ph↗

arXiv2025

Investigating New Physics through the Observables of Semileptonic $B_{s}\to K^{\ast}(\to K π)μ^{+}μ^{-}$ Decay

The rare four-fold decay $B_s \to K^*(\to Kπ)μ^+μ^- $, governed by the flavor-changing neutral current transition $b \to dμ^+μ^-$, provides a sensitive probe for testing the Standard Model (SM) and investigating signatures of new physics (NP). This work presents a comprehensive model-independent analysis of the decay using the framework of the weak effective field theory. We compute a set of key physical observables, including the differential branching ratio, forward-backward asymmetry, longitudinal polarization fraction, and several normalized angular coefficients $\langle I_i\rangle$, as a function of the dilepton invariant mass squared $q^2$. The impact of NP is explored via both one-dimensional (1D) and two-dimensional (2D) scenarios involving NP Wilson coefficients $C_7^{\text{NP}}$, $C_9^{(\prime)\text{NP}}$, and $C_{10}^{(\prime)\text{NP}}$. Our findings reveal notable deviations from the SM predictions across multiple observables. Furthermore, we analyze the correlations between different observables and their 2D contour plots which would be useful to further constrain the parametric space of possible NP contributions. This study reinforces the potential of $B_s \to K^* μ^+ μ^-$ decay as a complementary channel in the search for physics beyond the SM.

hep-ph↗

arXiv2025

Addressing the $R_{τ/{μ,e}}\left(D^{(*)}\right)$ puzzle through New Physics four-fermion operators and their impact on $Λ_{b}\rightarrowΛ_{c}τ\barν_τ$ decay

The Lepton Flavor Universality ratio $R_{τ/{μ,e}}\left(D^{(*)}\right)$ poses a challenge to the Standard Model (SM), as B-factory experiments, BaBar, Belle, and the LHCb show $3.31σ$ deviations from their theoretical predictions. Utilizing the latest HFLAV averages and incorporating the branching ratio constraints $60\%$, $30\%$ and $10\%$ from the lifetime of the $B_c$ meson, we determine the values of the Wilson coefficients (WCs) for different New Physics (NP) four-fermion operator with specific Lorentz structures. Our analysis finds that the WC scenario $\left(C_{S_{L}},C_{S_{R}}\right)$ is the most probable, the maximum pull from the SM, and strongly influenced by branching ratio constraints. Furthermore, we identify three degenerate solutions involving $C_{V_{L}}$, $C_{V_{L}}^{\prime}$, $C_{V_{L}}^{\prime\prime}$, and $C_{S_{R}}^{\prime\prime}$ as the second most probable NP scenarios. We then studied the influence of these NP operators on various physical observables in $Λ_{b}\rightarrowΛ_{c}τ\barν_τ$ decay by using the Lattice QCD form factors. Our results highlighted $C_{S_{L}}^{\prime\prime}$, $C_{S_{R}}$, $C_{T}$, $\left(C_{S_{L}},C_{S_{R}}\right)$, $\left(C_{S_{R}},C_{T}\right)$, and the three degenerate scenarios involving $\left(C_{S_{L}},C_{T}\right)$, $\left(C_{S_{L}}^{\prime},C_{T}^{\prime}\right)$ and $\left(C_{S_{L}}^{\prime\prime},C_{T}^{\prime\prime}\right)$ as strong indicators of NP. The correlation of different physical observables shows a direct correlation between $dΓ/dq^{2}$ and $P_{L}^τ$ for WC $\left(C_{S_{L}},C_{S_{R}}\right)$; and between $A_{FB}$ and $P_{L}^{Λ_{c}}$ for three degenerate WCs involving $\left(C_{S_{L}},C_{T}\right)$. We hope that the measurements of these observables in ongoing and future experiments will help us scrutinize these constraints on the various NP couplings.

hep-ph↗

arXiv2025

Exploring New Physics in transition $b\to s\,\ell^+\ell^-$ through different $B_c\to D_s^{(\ast)} \,\ell^+\ell^-$ observables

Inspired by the discrepancies observed in the $b\to s\ell^+\ell^-$ neutral current decays, we study the decay channel $B_c\to D_s^{(\ast)} \,\ell^+\ell^-$ ($\ell=μ,τ$), which is based on the same flavor changing neutral current (FCNC) transition at the quark level. The current study shows that this decay channel can provide a useful probe for physics beyond the standard model. We use the helicity formalism while employing the effective theory approach where we include the effects of vector and axial vector `new' physics (NP) operators. In this study, we have computed the branching ratio $\mathcal{B}_r$, the $D^\ast$ helicity fraction $f_L$, the lepton forward-backward asymmetry $\mathcal{A}_{FB}$, and the lepton flavor universality ratio (LFU) $R^{τμ}_{D_s^*}$. In addition, as a complementary check on the LFU, we also calculate the various other LFU observables, $R_{i}^{τμ}$ where $i=A_{FB}$, $f_L$. We assume that the NP universal coupling is present for both muons and tauons, while the non-universal coupling is only present for muons. Regarding these couplings, we employ the latest global fit to the $b\to s\ell^+\ell^-$ data, which is recently computed in arXiv:2304.07330. We give predictions of some of the mentioned observables within the SM and the various NP scenarios. We have found that not only are the considered observables sensitive to NP but are also helpful in distinguishing among the different NP scenarios. These results can be tested at the LHCb, HL-LHC, and FCC-ee, and therefore, a precise measurements of these observables not only deepens our understanding of the $b\to s\ell^+\ell^-$ process but also provides a window of opportunity to possibly study various NP scenarios.

hep-ph↗

arXiv2025

Polarization-dependent observables in $H\to \ell^{+}\ell^{-} γ$ in the SM

The rare three body decay of a Higgs boson to a lepton-anti lepton pair and a photon has begun to attract attention, after the first evidence for the $H\to Zγ$ at CMS and ATLAS, which is a sub process of $H \to \ell^+ \ell^- γ$ . To investigate some important features of this process, we suggest that the polarized forward-backward and the photon polarization asymmetries could be useful to probe its important properties, such as the behavior of Yukawa coupling, resonance, and non-resonance contributions. Our analysis introduces a comprehensive framework to evaluate the aforementioned polarization-dependent observables. By analyzing the polarization effects of the final-state photon and lepton separately on forward-backward asymmetries, we demonstrate that loop-induced contributions play a significant role to investigate these asymmetries. Unlike the unpolarized case, where the interference effects of resonance and non-resonance effects are minimal, we show that polarization dependent observables offer a powerful tool to analyze these features of this decay mode. Furthermore, these observables can provide a handy tool for probing possible signatures of physics beyond the SM.

hep-ph↗

arXiv2025

Polarized and un-polarized $\mathcal{R}_{K^*}$ in and beyond the SM

The Standard Model (SM) is lepton flavor universal, and the recent measurements of lepton flavor universality in $B \to (K,K^*)\ell^{+}\ell^{-}$, for $\ell = μ, \; e$, decays now lie close to the SM predictions. However, this is not the case for the $τ$ to $μ$ ratios in these decays, where there is still some window open for the new physics (NP), and to accommodate them various extensions to the SM are proposed. It will be interesting to identify some observables which are not only sensitive on the parametric space of such NP models but also have some discriminatory power. We find that the polarization of the $K^{*}$ may play an important role, therefore, we have computed the unpolarized and polarized lepton flavor universality ratios of $τ$ to $μ$ in $B\to K^{*}\ell^{+}\ell^{+}$, $\ell= μ, τ$ decays. The calculation shows that in most of the cases, the values of the various proposed observables fall within the current experimental sensitivity, and their study at some on going and future experiments will serve as a tool to segregate the variants of the NP models.

hep-ph↗

arXiv2024

Angular observables of the four-fold $B \to K_{1}(1270,1400)(\to V P) \ell^{+}\ell^{-}$ decays in and beyond the Standard Model

Recent measurements of the lepton flavor universality ratios $R^{μe}_{K}$ and $R^{μe}_{K^*}$ in $B\to \left(K, K^*\right)μ^{+}μ^{-}\left(e^+e^-\right)$ at LHCb align with the Standard Model predictions, necessitating search for the complementary decay modes. In this context, we derive the angular decay distributions of the four-fold $B \to K_{1}(1270,1400)(\to V P) μ^{+}μ^{-}$ decays, where $K_1 $ is an axial-vector meson, $V=ρ, K^{\ast}$, and $P=K, π$. Considering the weak effective Hamiltonian with vector and axial-vector new physics operators, and employing the helicity formalism, we obtain the four-dimensional differential decay distributions and extract various physical observables. These include differential branching ratios, lepton forward-backward asymmetry, forward-backward asymmetry for transversely polarized $K_1$ meson, longitudinal and transverse polarization fractions of the $K_1$ meson, and the normalized angular coefficients with longitudinally and transversely polarized final state vector meson $V$, in the cascade decay $K_1\to VP$. Based on the latest global fit analysis data for all $b\to s$ transitions, we predict the results of these observables in various bins of the square of the momentum transfer, $q^2$. Our findings indicate that these physical observables are not only sensitive to new physics but can also differentiate between various new physics scenarios in certain kinematical regions. The precise measurements of these observables in $B \to K_{1}(1270,1400)(\to V P) μ^{+}μ^{-}$ decays at current and future experiments will provide opportunities for the complementary searches for physics beyond the Standard Model in $b\to s\ell^+\ell^-$ decays.

hep-ph↗

arXiv2024

Semileptonic $W$ Decay to the $B$ Meson with Lepton Pairs in Heavy Quark Effective Theory Factorization upto $\mathcal{O}$$(α_s)$

Motivated by the study of heavy-light meson production within the framework of heavy quark effective theory (HQET) factorization, we extend the factorization formalism for a rather complicated process $W^+\to B^+\ell^+\ell^-$ in the limit of a non-zero invariant squared-mass of dilepton, $q^2$, at the lowest order in $1/m_b$ up to $\mathcal{O}(α_s)$. The purpose of the current study is to extend the HQET factorization formula for the $W^+\to B^+\ell^+\ell^-$ process and subsequently compute the form factors for this channel up to next-to-leading-order corrections in $α_s$. We explicitly show the amplitude of the $W^+\to B^+\ell^+\ell^-$ process can also be factorized into a convolution between the perturbatively calculable hard-scattering kernel and the non-perturbative yet universal light-cone distribution amplitude (LCDA) defined in HQET. The validity of HQET factorization depends on the assumed scale hierarchy $m_W \sim m_b \gg Λ_{\mathrm{QCD}}$. Within the HQET framework, we evaluate the form factors associated with the $W^+ \rightarrow B^+\ell^+\ell^-$ process, providing insights into its phenomenology. In addition, we also perform an exploratory phenomenological study on $W^+ \rightarrow B^+\ell^+\ell^-$ by employing an exponential model for the LCDAs for $B^+$ meson. Our findings reveal that the branching ratio for $W^+ \rightarrow B^+\ell^+\ell^-$ is below $10^{-10}$. Although the branching ratios are small, this channel in high luminosity LHC experiments may serve to further constraints the value of $λ_B$.

hep-ph↗