118135338
CP violation induced by the interference of scalar and vector resonances in three-body decays of bottom mesons
Large CP violation is an interesting phenomenon both theoretically and experimentally. Last year, LHCb Collaboration found in some three-body decays of bottom mesons that large CP violations appear in regions of the Dalitz plots that are not dominated by contributions from narrow resonances. In this paper, we present a mechanism which can induce such kind of large CP violations. In this mechanism, large localized CP asymmetries in phase space can be induced by the interference of two intermediate resonances with different spins. We also apply this mechanism to the decay channel $B^\pm\to K^\pm \pi^+\pi^-$.
119180550
Anomalous tqZ coupling effects in rare B- and K-meson decays
A bstractAs a top-factory, the LHC is performing a direct study of top-quark anomalous FCNC couplings, which are, however, correlated closely with the rare B- and K-meson decays. In this paper, we study the effects of anomalous tqZ (with q = u, c) couplings in the rare decays Bs,d → μ+μ−, B → Xsν$ \overline \nu $, B → K(*)ν$ \overline \nu $, K+ → π+ν$ \overline \nu $, and KL → π0ν$ \overline \nu $. With the up-to-date experimental bounds on the branching ratios of these channels, constraints on the left-handed anomalous couplings $ X_{{ct}}^L $ and $ X_{{ut}}^L $ are derived, respectively. With these low-energy constraints taken into account, we find that, for real couplings $ X_{{ct}}^L $ and $ X_{{ut}}^L $, the indirect upper bounds on B(t → qZ) are much lower than that from the D0 collaboration, but are still compatible with the 5σ discovery potential of ATLAS with an integrated luminosity of 10 fb−1. With refined measurements to be available at the LHCb, the future super-B factories, the NA62 at CERN, and the KOTO at J-PARC, closer correlations between the t → qZ and the rare B- and K-meson decays are expected in the near future, which will be helpful for the searches of the top-quark FCNC decays at the LHC.
118478453
Constraints on anomalous $tcZ$ coupling from $\bar B \to \bar K^* \mu^+ \mu^-$ and $B_s \to \mu^+ \mu^-$ decays
In this paper, we analyze the possible anomalous $tcZ$ coupling effects in the $b \to s $ mediated decays $\bar B \to \bar K^* \mu^+ \mu^-$ and $B_s \to \mu^+ \mu^-$. After exploiting the available experimental data, the combined constraints on the anomalous coupling $X_{ct}^L$ are derived. It is found that, the bound on the magnitude $|X_{ct}^L|$ is dominated by the branching ratios of these two decays. Furthermore, one sign-flipped solution is excluded by the longitudinal fraction of $\bar B \to \bar K^* \mu^+ \mu^-$ at the low dilepton mass region. After considering the combined constraints, for general complex coupling $X_{ct}^L$, the predicted upper bound on $\mathcal B (t \to cZ)$ are compatible with that from the recent CMS direct search. In particular, for the case of real coupling $X_{ct}^L$, the upper bound reads $\mathcal B (t \to cZ)<1.0\times 10^{-4}$, which is much lower than the current CMS bound but still accessible at the LHC. With improved measurements at the LHC, the colser correlations between the $t \to cZ$ and $b \to s$ mediated (semi-) leptonic decays are expected in the near future.
118024604
Exclusive radiative B-meson decays within minimal flavor-violating two-Higgs-doublet models
In the "Higgs basis" for a generic two-Higgs-doublet model, only one doublet gets a nonzero vacuum expectation value and, under the criterion of minimal flavor violation, the other one is fixed to be either color-singlet or color-octet, referred to, respectively, as the type-III and type-C models. Both of them can naturally avoid large FCNC transitions and provide very interesting phenomena in some low-energy processes. In this paper, we study their effects on exclusive radiative B-meson decays due to the exchange of colorless or colored charged Higgs. It is found that while constraints from the branching ratios are slightly weaker than the ones from the inclusive B -> X-s gamma decay, the isospin asymmetries in exclusive decays provide very complementary bounds on the model parameters. As the two models predict similar corrections to the dipole coefficient C-7(eff), but similar magnitudes with opposite signs to C-8(eff), the branching ratios cannot discriminate the two models, and we have to resort to the direct CP and isospin asymmetries of b -> s processes, which are more sensitive to C-8(eff). Due to the CKM factors vertical bar lambda((d))(u)vertical bar similar to vertical bar lambda((d))(t)vertical bar, the terms proportional to lambda((d))(u) make the observables of b -> d processes exhibit a different dependence on the possible new physics phase. In addition, correlations between the various observables in the exclusive B -> V gamma and the inclusive B -> X-s,X-d gamma decays are investigated, which could provide further insights into the models with more precise experimental measurements and theoretical predictions for these decays.
120402686
Perturbative QCD estimation of the Bc exclusive nonleptonic decays
We argue that the B-c exclusive nonleptonic decays are perturbatively calculable. Working in a perturbative QCD model of Brodsky et al, we pay attention to the estimate of the partial widths of the modes B-c --> J/Psi pi(+), J/Psi rho(+), etc., which serve to identify B-c mesons and determine the B-c mass and life time. Our estimations are found to be lower than the other predictions. We note that the spectator ansatz might be misleading in dealing with B-c weak decays. So the results will be potentially important at LHC to measure the B-c meson and to test various models of weak decays of heavy mesons.
1542336
Extracting Cabibbo-Kobayashi-Maskawa elements in Bc semileptonic decays and heavy quark spin symmetry.
We discuss the extraction of \ensuremath{\Vert}${\mathit{V}}_{\mathit{c}\mathit{s}}$/${\mathit{V}}_{\mathit{c}\mathit{d}}$\ensuremath{\Vert},\ensuremath{\Vert}${\mathit{V}}_{\mathit{c}\mathit{s}}$/${\mathit{V}}_{\mathit{u}\mathit{b}}$\ensuremath{\Vert}, and \ensuremath{\Vert}${\mathit{V}}_{\mathit{c}\mathit{d}}$/${\mathit{V}}_{\mathit{u}\mathit{b}}$\ensuremath{\Vert} from semileptonic ${\mathit{B}}_{\mathit{c}}$ decay in the heavy quark limit. The first corrections to the corresponding ratios of the differential rates of ${\mathit{B}}_{\mathit{c}}$ semileptonic decays are calculated in the zero recoil point within HQET combined with the results of QCD sum rules and chiral perturbation theory, and within the quark model. Special attention is paid to minimize the theoretical uncertainties in the procedure of extracting the ratios. We find many uncertainties can be canceled naturally in the leading level. The ratios also are insensitive to the QCD energy scale \ensuremath{\mu} in the next-to-leading level. The result is potentially important for extracting CKM elements from future measurements at the CERN LHC.
121575220
Elastic O-16+Ne-20 scattering from a folding model analysis
A folding potential for elastic O-16+Ne-20 scattering is constructed based on the four-alpha-particle model for the O-16 nucleus and the alpha+O-16 model for the Ne-20 nucleus. The elastic scattering angular distributions of the O-16+Ne-20 system in the energy range of E-c.m. = 24.5-35.5 MeV are calculated by use of the alpha-folding potential obtained. The calculations show that the experimental data can be reasonably well described. The surface term in the imaginary potential has a significant effect on the calculations of the cross section at large angles for the energies considered.
119236514
Scalar Glueball in Radiative J/psi Decay on the Lattice
The form factors in the radiative decay of J/psi to a scalar glueball are studied within quenched lattice QCD on anisotropic lattices. The continuum extrapolation is carried out by using two different lattice spacings. With the results of these form factors, the partial width of J/psi radiatively decaying into the pure gauge scalar glueball is predicted to be 0.35(8) keV, which corresponds to a branching ratio of 3.8(9) x 10(-3). By comparing with experiments, out results indicate that f(0)(1710) has a larger overlap with the pure gauge glueball than other related scalar mesons. DOI: 10.1103/PhysRevLett.110.021601
119232831
Prediction for the mass spectra of resonance mesons in the soft-wall AdS/QCD model with a modified 5D metric
A soft-wall anti-de Sitter/QCD model with a modified five-dimensional metric at the infrared region is constructed to obtain a nontrivial dilaton solution, which incorporates the chiral symmetry breaking and linear confinement. By taking the pion mass and decay constant as two input mass scales, the resulting predictions for the resonance states of pseudoscalar, scalar, vector, and axial-vector mesons agree remarkably with the experimentally confirmed resonance states. The effects of the quartic interaction term are investigated by taking an appropriate sign and magnitude for maintaining the stability of the bulk scalar potential. It is shown that such a simply modified soft-wall anti-de Sitter/QCD model can lead to a consistent prediction for the mass spectra of resonance states in the pseudoscalar, scalar, vector, and axial-vector mesons; the agreement with the experimental data is found to be better than 10% for the excited meson states. The resulting pion form factor also agrees well with the experimental data.
119272630
Charmless B-s -> PP, PV, VV decays based on the six-quark effective Hamiltonian with strong phase effects II
We provide a systematic study of charmless B-s -> PP, PV, VV decays (P and V denote pseudoscalar and vector mesons, respectively) based on an approximate six-quark operator effective Hamiltonian from QCD. The calculation of the relevant hard-scattering kernels is carried out, the resulting transition form factors are consistent with the results of QCD sum-rule calculations. By taking into account important classes of power corrections involving "chirally enhanced" terms and the vertex corrections as well as weak annihilation contributions with non-trivial strong phase, we present predictions for the branching ratios and CP asymmetries of B-s decays into PP, PV and VV final states, and also for the corresponding polarization observables in VV final states. It is found that the weak annihilation contributions with non-trivial strong phase have remarkable effects on the observables in the color-suppressed and penguin-dominated decay modes. In addition, we discuss the SU(3) flavor symmetry and show that the symmetry relations are generally respected.
110720564
THE INSTALLATION OF ONE 14 METER CELL OF TPS VACUUM SYSTEM
The construction of a new 3 GeV synchrotron facility, Taiwan Photon Source, is ongoing. The vacuum system has been designed with off-site baking for arc section from sector gate valve to sector gate valve. There is no flange used in this arc section besides the two ends connected to sector gate valves. It is a tedious works for install such long vacuum system with aluminium chambers. In this paper, all the detailed installation procedures will be described. All the precaution inspection procedures for all vacuum components to prevent failed components to be installed will also be described. Every three weeks, one cell will be assembled and stored. Experience is being learned and could be used for the vacuum system of future new accelerator like FEL and others.