We present a precise calculation of the dilepton invariant-mass spectrum and the decay rate for $B^pm to pi^pm ell^+ ell^-$ ($ell^pm = e^pm, mu^pm $) in the Standard Model (SM) based on the effective Hamiltonian approach for the $b to d ell^+ ell^-$
transitions. With the Wilson coefficients already known in the next-to-next-to-leading logarithmic (NNLL) accuracy, the remaining theoretical uncertainty in the short-distance contribution resides in the form factors $f_+ (q^2)$, $f_0 (q^2)$ and $f_T (q^2)$. Of these, $f_+ (q^2)$ is well measured in the charged-current semileptonic decays $B to pi ell u_ell$ and we use the $B$-factory data to parametrize it. The corresponding form factors for the $B to K$ transitions have been calculated in the Lattice-QCD approach for large-$q^2$ and extrapolated to the entire $q^2$-region using the so-called $z$-expansion. Using an $SU(3)_F$-breaking Ansatz, we calculate the $B to pi$ tensor form factor, which is consistent with the recently reported lattice $B to pi$ analysis obtained at large~$q^2$. The prediction for the total branching fraction ${cal B} (B^pm to pi^pm mu^+ mu^-) = (1.88 ^{+0.32}_{-0.21}) times 10^{-8}$ is in good agreement with the experimental value obtained by the LHCb Collaboration. In the low $q^2$-region, heavy-quark symmetry (HQS) relates the three form factors with each other. Accounting for the leading-order symmetry-breaking effects, and using data from the charged-current process $B to pi ell u_ell$ to determine $f_+ (q^2)$, we calculate the dilepton invariant-mass distribution in the low $q^2$-region in the $B^pm to pi^pm ell^+ ell^-$ decay. This provides a model-independent and precise calculation of the partial branching ratio for this decay.
We calculate the cross sections and final state distributions for the processes e^+ e^- --> Upsilon(1S) (pi^+ pi^-, K^+ K^-, eta pi^0) near the Upsilon(5S) resonance based on the tetraquark hypothesis. This framework is used to analyse the data on th
e Upsilon(1S) pi^+ pi^- and Upsilon(1S) K^+ K^- final states [K.F. Chen et al. (Belle Collaboration), Phys. Rev. Lett. 100, 112001 (2008); I. Adachi et al. (Belle Collaboration), arXiv:0808.2445], yielding good fits. Dimeson invariant mass spectra in these processes are shown to be dominated by the corresponding light scalar and tensor states. The resulting correlations among the cross sections are worked out. We also predict sigma(e^+ e^- --> Upsilon(1S) K^+ K^-)/sigma(e^+ e^- --> Upsilon(1S) K^0 Kbar^0) = 1/4. These features provide crucial tests of the tetraquark framework and can be searched for in the currently available and forthcoming data from the B factories.
The extensions of the minimal supersymmetric model (MSSM), driving mainly from the need to solve the mu problem, involve novel matter species and gauge groups. These extended MSSM models can be searched for at the LHC via the effects of the gauge and
Higgs bosons or their fermionic partners. Traditionally, the focus has been on the study of the extra forces induced by the new gauge and Higgs bosons present in such models. An alternative way of studying such effects is through the superpartners of matter species and the gauge forces. We thus consider a $U(1)^prime$ gauge extension of the MSSM, and perform an extensive study of the signatures of the model through the production and decays of the scalar quarks and gluino, which are expected to be produced copiously at the LHC. After a detailed study of the distinctive features of such models with regard to the signatures at the LHC, we carry out a detailed Monte Carlo analysis of the signals from the process pp-> n leptons + m jets + EMT, and compare the resulting distributions with those predicted by the MSSM. Our results show that the searches for the extra gauge interactions in the supersymmetric framework can proceed not only through the forces mediated by the gauge and Higgs bosons but also through the superpartner forces mediated by the gauge and Higgs fermions. Analysis of the events induced by the squark/gluino decays presented here is complementary to the direct Z searches at the LHC.
