arXiv subjects

Arslan Sikandar

Publications and source records attributed to Arslan Sikandar.

7 recordsLinked to original sources

arXiv2026

Improved $B\to K^*_0\left(1430\right)$ transition form factors at next-to-leading order in light cone sum rules

We present an improved determination of the $B\to K_0^*(1430)$ transition form factors using light-cone sum rules (LCSR) with an expansion near the light cone. We include the one-loop radiative corrections to the twist-2 and asymptotic twist-3 distribution amplitudes of the scalar meson and perform the calculation consistently in the $\overline{\mathrm{MS}}$ scheme. It allowed us to quantify the impact of radiative corrections on the form factors for each twist. A daughter sum rule is used from the $B\to K_0^*(1430)$ LCSR to ascertain Borel mass and threshold parameter simultaneously. We find that the dominant theoretical uncertainties arise from the $K_0^*(1430)$ distribution amplitudes and its decay constant. Our results are presented in a form that facilitates the incorporation of future improvements in these nonperturbative inputs, including those from lattice QCD and experimental measurements, and can be readily extended to other scalar mesons.

hep-ph↗

arXiv2026

Symmetry-Breaking Effects on Form Factors and Observables in $B \to K_0^*(1430)μ^+μ^-$ Decay

In the heavy-quark and large-energy limits, symmetry relations reduce the number of independent form factors governing heavy-to-light $B$-meson decays. Exploiting these relations, the form factors can be parametrized while systematically incorporating symmetry-breaking corrections from perturbative QCD. Using vertex renormalization together with light-cone distribution amplitudes, we compute the vertex and hard-spectator contributions for the $B \to K_0^*(1430)$ transition. We then analyze the impact of these form factors on physical observables, including the branching ratio and lepton polarization asymmetries $(P_L, P_N)$, in $B \to K_0^*(1430)μ^+μ^-$. Our results indicate that perturbative corrections induce modest shifts of $\sim 3\%$ in both the branching ratio and the normal lepton polarization asymmetry. Consequently, any significant deviation observed experimentally from these predictions would provide a clear signal of potential New Physics effects.

hep-ph↗

arXiv2026

Vector Leptoquark Mediated Leptonic Decay of the Charged $B$-Meson

We study the purely leptonic decay of the charged $B$-meson within the $U_1$ Vector Leptoquark model at both leading-order and with one-loop QCD corrections. The structure of this amplitude is characterised by direct quark-lepton couplings which allow for lepton flavour universality violation (LFUV) and additional loop-level topologies. The leptoquark channel contributions to the $B$-meson decay constant are computed and accommodated in its lattice-improved uncertainty bounds by constraining the parameter space of this model in two distinct new-physics scenarios. Under these constraints, we provide predictions for both the LFUV and non-LFUV contributions to the branching fractions of this decay.

hep-ph↗

arXiv2025

Radiative B to tensor meson decays at NLO in SCET

The radiative $B$ to tensor $\left(K_2^*(1430),\; f_2(1270),\; a_2(1230)\right)$ 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 $ζ^\perp_{T}$ and branching ratios for these $B$ to tensor meson decays. In the case of $B\to K_2^*(1430)γ$, the numerical value of the branching ratio lies close to its experimental measurements. The estimated values of the branching ratios of CKM suppressed decays $B \to \left(a_2(1230),\; f_2(1270)\right)γ$ are significant small compared to that of $B\to K_2^*(1430)γ$, but still could be measured in some ongoing and future $B$ physics experiments.

hep-ph↗

arXiv2023

Radiative $B$ to axial-vector meson decays at NLO in Soft-Collinear Effective Theory

The rare decay $B\rightarrow Aγ$, 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 $\mathcal{O}(α_s)$ diagrams that contribute to matching to SCET$_I$. The new intermediate theory is matched onto SCET$_{II}$ and the running of SCET$_I$ operators is performed to sum large perturbative logarithms. The values of soft-overlap function $ζ_{\perp}$ for $K_1 (1270,\;1400), a_{1}$ and $b_{1}$ mesons are estimated from the light cone-sum-rules (LCSR), and later using it the corresponding branching fractions for $B \to \left(K_{1}(1270,\; 1400),\; a_{1},\; b_{1}\right)γ$ decays are calculated. We find that in case of $B \to K_{1}(1270,\; 1400)γ$ decays the results are in good agreement with their experimental measurements. Also the estimated values of the branching ratios of the $B \to (b_{1},\; a_1)γ$ decays are potentially large to be measured at the LHCb and future B-factories.

hep-ph↗

arXiv2019

Universal critical behavior in tensor models for four-dimensional quantum gravity

Four-dimensional random geometries can be generated by statistical models with rank-4 tensors as random variables. These are dual to discrete building blocks of random geometries. We discover a potential candidate for a continuum limit in such a model by employing background-independent coarse-graining techniques where the tensor size serves as a pre-geometric notion of scale. A fixed point candidate which features two relevant directions is found. The possible relevance of this result in view of universal results for quantum gravity and a potential connection to the asymptotic-safety program is discussed.

gr-qc↗

arXiv2019

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

The symmetries arise due to heavy quark and large energy limit help us to reduce the number of independent form factors in the heavy-to-light $B$-meson decays. It is expected that these symmetry relations are not exact and are broken by the perturbative effects, namely, the vertex corrections and the hard-spectator scatterings. The former are included in the form factors via vertex renormalization whereas the later are calculated through light-cone distribution amplitudes. We first calculate these symmetry breaking corrections to the form factors involved in semileptonic $B$-meson to an axial-vector $(K_{1})$-meson decay. Later, by using these form factors we see their effect on the physical observables such as the zero-position of the forward-backward $(\mathcal{A}_{FB})$ asymmetry and the longitudinal lepton polarization ($P_L$) asymmetry in $B\rightarrow K_1(1270) μ^+μ^-$ decay. We find that as a result of these corrections to the form factors, the zero-position of the forward-backward asymmetry is shifted by $10\%$ from its SM value while the effects on $P_L$ are rather insignificant.

hep-ph↗