Mixed QCD-EW corrections for Higgs leptonic decay via HW+W− vertex

We consider the two-loop corrections to the HW+W− vertex at order ααs. We construct a canonical basis for the two-loop integrals using the Baikov representation and the intersection theory. By solving the ϵ-form differential equations, we obtain fully analytic expressions for the master integrals in terms of multiple polylogarithms, which allow fast and accurate numeric evaluation for arbitrary configurations of external momenta. We apply our analytic results to the decay process H → νeeW, and study both the integrated and differential decay rates. Our results can also be applied to the Higgs production process via W boson fusion.

Search for the rare semi-leptonic decay J/ψ → D−e+νe + c.c.

Using 10.1 × 109J/ψ events produced by the Beijing Electron Positron Collider (BEPCII) at a center-of-mass energy $$ \sqrt{s} $$ s = 3.097 GeV and collected with the BESIII detector, we present a search for the rare semi-leptonic decay J/ψ → D−e+νe + c.c. No excess of signal above background is observed, and an upper limit on the branching fraction ℬ(J/ψ → D−e+νe + c. c.) < 7.1 × 10−8 is obtained at 90% confidence level. This is an improvement of more than two orders of magnitude over the previous best limit.

A new B-flavour anomaly in Bd,s → $$ {K}^{\ast 0}{\overline{K}}^{\ast 0} $$: anatomy and interpretation

In the context of the recently measured non-leptonic decays Bd→$$ {K}^{\ast 0}{\overline{K}}^{\ast 0} $$ K ∗ 0 K ¯ ∗ 0 and Bs→$$ {K}^{\ast 0}{\overline{K}}^{\ast 0} $$ K ∗ 0 K ¯ ∗ 0 we analyse the anatomy of the LVV observable that compares the longitudinal components of Bs→VV and Bd→VV decays. This observable is cleaner than the longitudinal polarisation fraction as it is afflicted only at subleading order in a 1/mb expansion by the theoretical uncertainties arising in the transverse components entering the polarisation fraction. Focusing on the particular case of Bd→$$ {K}^{\ast 0}{\overline{K}}^{\ast 0} $$ K ∗ 0 K ¯ ∗ 0 and Bs→$$ {K}^{\ast 0}{\overline{K}}^{\ast 0} $$ K ∗ 0 K ¯ ∗ 0 , we discuss the main sources of hadronic uncertainty in the SM. We find for the SM prediction $$ {L}_{K^{\ast }{\overline{K}}^{\ast }}={19.5}_{-6.8}^{+9.3} $$ L K ∗ K ¯ ∗ = 19.5 − 6.8 + 9.3 , which implies a 2.6σ tension with respect to the most recent data, pointing to a deficit in the b→s transition of the non-leptonic decay versus the corresponding b→d transition. We discuss possible New Physics explanations for this deviation, first at the level of the Weak Effective Theory and we identify that the two Wilson coefficients $$ {\mathcal{C}}_4 $$ C 4 and $$ {\mathcal{C}}_{8g} $$ C 8 g can play a central role in explaining this anomaly. Finally, we briefly explore two different simplified New Physics models which can explain the anomaly through a contribution either in $$ {\mathcal{C}}_4 $$ C 4 (Kaluza-Klein gluon) or in $$ {\mathcal{C}}_{8g} $$ C 8 g , with a significant amount of fine tuning, but possible connections to the b→sℓℓ anomalies.

Exclusive dilepton production at forward rapidities in PbPb collisions

The dilepton production at forward rapidities in diffractive and exclusive processes present in ultraperipheral PbPb collisions at the LHC is investigated. Predictions for the $$e^+ e^-$$ e + e - , $$\mu ^+ \mu ^-$$ μ + μ - and $$\tau ^+ \tau ^-$$ τ + τ - cross sections are presented taking into account of realistic cuts that can be implemented by the LHCb Collaboration in a future experimental analysis. Our results indicate that the background associated with the diffractive production can be strongly suppressed and the exclusive processes can be cleanly separated. For the $$\tau ^+ \tau ^-$$ τ + τ - production, the semi and purely leptonic decay channels are considered. Our results indicate that a future experimental analysis of the dilepton production at the LHCb is feasible and can be useful to search for BSM physics.

Importance of confinement in instanton induced potential for bottomonium spectroscopy

Mass spectra of bottomonium states are computed using the Instanton Induced potential obtained from Instanton Liquid Model for QCD vacuum and incorporating a stronger confinement term. Spin dependent interactions through confined one gluon exchange potential are incorporated to remove the mass degeneracy. The mass spectra of the $$b\bar{b}$$ b b ¯ states up to 4S states are found to be in good agreement with the values reported by PDG(2020). Mixing of nearby isoparity states are also studied. We found the state $$\varUpsilon (10{,}860)$$ Υ ( 10 , 860 ) as an admixture of $$5^3S_1$$ 5 3 S 1 and $$6^3D_1$$ 6 3 D 1 Upsilon states with mixing angle $$\theta = 39.98^{\circ }$$ θ = 39 . 98 ∘ and the mixed state di-leptonic decay width is found to be 0.25 keV as against the width of $$0.31 \pm 0.07$$ 0.31 ± 0.07 keV reported by PDG. Further the state $$\varUpsilon (11{,}020)$$ Υ ( 11 , 020 ) is also found to be the admixture of $$6^3S_1$$ 6 3 S 1 and $$5^3D_1$$ 5 3 D 1 Upsilon states with the mixing angle $$\theta = 51.69^{\circ }$$ θ = 51 . 69 ∘ and the di-leptonic decay width of the mixed state is obtained as 0.14 keV which is very close to the width of $$0.13 \pm 0.03$$ 0.13 ± 0.03 keV reported by PDG. Present results indicates that addition of confinement to the instanton potential is crucial for the determination of the mass spectroscopy of heavy hadrons.

Completing 1/$$ {m}_b^3 $$ corrections to non-leptonic bottom-to-up-quark decays

We compute the contributions of dimension six two-quark operators to the non-leptonic decay width of heavy hadrons due to the flavor changing bottom-to-up-quark transition in the heavy quark expansion. Analytical expressions for the Darwin term ρD and the spin-orbit term ρLS are obtained with leading order accuracy.