The exclusive B_s -> phi mu+ mu- process in a constituent quark model

We consider the exclusive B_s -> phi mu+ mu- process in the standard model using a constituent quark loop model approach together with a simple parameterization of the quark dynamics. The model allows to compute the decay form factors and therefore can give predictions for the decay rates, the invariant mass spectra and the asymmetries. This process is suppressed in the standard model but can be enhanced if new physics beyond the standard model is present, such as flavor-violating supersymmetric models. It constitutes therefore an interesting precision test of the standard model at forthcoming experiments.Comment: 17 pages, 6 figures, 5 tables, LaTeX; minor changes to the introduction, table III and figure 3. Few references adde

Next-to-leading order QCD corrections to W+W+W^+W^+ and W−W−W^-W^- production in association with two jets

We present a study of $W^+W^+jj$ and $W^-W^-jj$ production including leptonic decays in hadron-hadron collisions. The full electroweak and QCD induced contributions and their interferences are calculated at leading order. We find that, for inclusive cuts, the interference effects can be large if the jets are produced with large transverse momentum where, however, the production rate is suppressed. We also discuss the vector-boson-fusion (VBF) cuts and show the validity of the VBF approximation. The NLO QCD corrections to the QCD-induced channels are also calculated. Compared to the previous calculation, we allow the intermediate $W$ bosons to be off-shell. For on-shell $W$ production, we obtain an excellent agreement with previous results. Our code will be publicly available as part of the parton level Monte Carlo program VBFNLO.Comment: 10 pages, 11 figures, 4 tables, v2: added results using a 2nd scale choice, accepted for publication in Phys. Rev.

Holographic three flavor baryon in the Witten-Sakai-Sugimoto model with the D0-D4 background

With the construction of the Witten-Sakai-Sugimoto model in the D0-D4 background, we systematically investigate the holographic baryon spectrum in the case of three flavors. The background geometry in this model is holographically dual to $U\left(N_{c}\right)$ Yang-Mills theory in large $N_{c}$ limit involving an excited state with a nonzero $\theta$ angle or glue condensate $\left\langle \mathrm{Tr}\mathcal{F}\wedge\mathcal{F}\right\rangle =8\pi^{2}N_{c}\tilde{\kappa}$, which is proportional to the charge density of the smeared D0-branes through a parameter $b$ or $\tilde{\kappa}$. The classical solution of baryon in this model can be modified by embedding the Belavin-Polyakov-Schwarz-Tyupkin (BPST) instanton and we carry out the quantization of the collective modes with this solution. Then we extend the analysis to include the heavy flavor and find that the heavy meson is always bound in the form of the zero mode of the flavor instanton in strong coupling limit. The mass spectrum of heavy-light baryons in the situation with single- and double-heavy baryon is derived by solving the eigen equation of the quantized collective Hamiltonian. Afterwards we obtain that the constraint of stable baryon states has to be $1<b<3$ and the difference in the baryon spectrum becomes smaller as the D0 charge increases. It indicates that quarks or mesons can not form stable baryons if the $\theta$ angle or glue condensate is sufficiently large. Our work is an extension of the previous study of this model and also agrees with those conclusions.Comment: 35 pages, 2 figures, 1 table, this version includes the acknowledgement and some revision