Vertex renormalization and hard scattering symmetry breaking corrections to 
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 to axial vector meson form factors at large recoil

Self Cite

The rare decay B → Aγ, with A representing axial-vector mesons such as K 1(1270), K 1(1400), b 1(1300), a 1(1260), is studied at next-to-leading order (NLO) in soft collinear effective theory (SCET). The large outgoing meson energy encourages the study of the decay with an appropriate factorization scheme that separates the factorizable and non-factorizable parts systematically. We have analyzed the leading-power and O ( α s ) diagrams that contribute to matching to SCETI. The new intermediate theory is matched onto SCETII and the running of SCETI operators is performed to sum large perturbative logarithms. The values of soft-overlap function ζ ⊥ for K 1(1270, 1400), a 1 and b 1 mesons are estimated from the light cone-sum-rules, and later using it the corresponding branching fractions for B → K 1 ( 1270 , 1400 ) , a 1 , b 1 γ decays are calculated. We find that in case of B → K 1(1270, 1400)γ decays the results are in good agreement with their experimental measurements. Also the estimated values of the branching ratios of the B → (b 1, a 1)γ decays are potentially large to be measured at the LHCb and future B-factories.

Section: Soft-overlap Function and Branching Fractionssupporting

confidence: 92%

Section: Scet II Operators and Scet I → Scet Ii Matchingmentioning

confidence: 98%

Radiative B to axial-vector meson decays at NLO in soft-collinear effective theory

Sikandar¹,

Aslam²,

Ahmed³

et al. 2021

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“…Similarly, the symmetry relations when these decays involve the semi-light (m ∼ [1-1.5 GeV]) axial-vector and tensor mesons were first obtained by Ebert et al [20]. At O(α s ), the symmetry breaking corrections in the case B to axial-vector mesons (K 1 (1270), K 1 (1400)) were calculated in [21]. It is, therefore, interesting to find such corrections when B decaying to the tensor mesons, K * 2 (1430), f 2 (1270) and a 2 (1320), all having J P = 2 + .…”

Section: Introductionmentioning

confidence: 94%

“…We can see that figure 1 contains both ultraviolet (UV) and IR divergences. The UV divergences get regulated by dimensional regularization, while to regulate the IR divergences, we introduce a small gluon mass λ [21]. We use the same IR regulator for full theory and HQET/LEET and notice that the IR terms have the same Dirac structure Γ which allows these contributions to be absorbed in soft-form factors.…”

Section: Vertex Correctionsmentioning

confidence: 99%

Symmetry breaking radiative corrections to B to tensor meson form factors at large recoil

Sikandar¹,

Aslam²,

Ahmed³

et al. 2022

Self Cite

In heavy-to-light $B$ decays, the heavy-quark/large-energy symmetry reduces the number of QCD form factors. At large final state meson energy, these form factors receive sizeable perturbative corrections. The hard-gluon vertex corrections are absorbed in the coefficients of soft-form factors, while the hard-spectator interactions generate symmetry-breaking corrections and end-point singularities. At an order of $1/m_b$, using the heavy-quark/large-energy symmetry, the end-point singularities can also be absorbed in the soft form factors, whereas the symmetry breaking corrections add separately to the form factors. In this work, we calculate these perturbative corrections for $B\rightarrow T\mu^{+}\mu^{-}$ decays, with $T$ representing the tensor mesons $K^*_2,\; f_2,\; a_2$ all having $J^P=2^+$. We find that the values of the branching ratio $(Br)$ and the zero-position of the forward-backward asymmetry $(\mathcal{A}_{FB})$ of $B\to K^*_2 \mu^{+}\mu^{-}$ decay receive nearly $5\%$ and $14\%$ contributions, respectively, from these radiative corrections. Compared to these observables, the radiative corrections change the averaged longitudinal lepton polarization asymmetry ($\langle P_L\rangle$) by $13\%$. Therefore, prior to attributing any deviation from the SM predictions of these asymmetries as a hint of NP, one has to take into account the contributions of vertex and hard-spectator corrections.

“…Similar decay involving axial-vector meson in the final state, i.e. B → Aγ is calculated in the context of large-energy-effective theory (LEET) [7] and using soft-collinear effective theory (SCET) [8]. The radiative…”

Section: Introductionmentioning

confidence: 99%

Radiative B to tensor meson decays at NLO in SCET

Sikandar

Aslam

2023

The radiative $B$ to tensor $\left(K_2^*(1430),\; f_2(1270),\; a_2(1320)\right)$ meson decays are studied at next-to-leading order (NLO) in soft-collinear effective theory (SCET). The SCET allows the systematic treatment of factorizable and non-factorizable contributions along with the resummation of large perturbative logarithms. We performed a two step matching and determined the soft-overlap function $\zeta^\perp_{T}$ and branching ratios for these $B$ to tensor meson decays. In the case of $B\to K_2^*(1430)\gamma$, the numerical value of the branching ratio lies close to its experimental measurements. The estimated values of the branching ratios of CKM suppressed decays $B \to \left(a_2(1320),\; f_2(1270)\right)\gamma$ are significant small compared to that of $B\to K_2^*(1430)\gamma$, but still could be measured in some ongoing and future $B$ physics experiments.