Search for B(s)(0) → μ+ μ- and B(0) → μ+ μ- decays in pp collisions at sqrt[s] = 7 TeV

A search for the rare decays B(s)(0) → μ+ μ- and B(0) → μ+ μ- is performed in pp collisions at sqrt[s] = 7 TeV, with a data sample corresponding to an integrated luminosity of 1.14 fb(-1), collected by the CMS experiment at the LHC. In both cases, the number of events observed after all selection requirements is consistent with expectations from background and standard-model signal predictions. The resulting upper limits on the branching fractions are B(B(s)(0) → μ+ μ-) < 1.9 × 10(-8) and B(B(0) → μ+ μ-)<4.6 × 10(-9), at 95% confidence level.     

Search for lepton number violating decays B+ → π- μ+ μ+ and B+ → K- μ+ μ+

A search is performed for the lepton number violating decay B+ → h- μ+ μ+, where h- represents a K- or a π-, using an integrated luminosity of 36 pb(-1) of data collected with the LHCb detector. The decay is forbidden in the standard model but allowed in models with a Majorana neutrino. No signal is observed in either channel and limits of B(B+ → K- μ+ μ+) < 5.4×10(-8) and B(B+ → π- μ+ μ+) < 5.8×10(-8) are set at the 95% confidence level. These improve the previous best limits by factors of 40 and 30, respectively.     

Differential branching fraction and angular analysis of the decay B0 → K*0 μ+ μ-

The angular distributions and the partial branching fraction of the decay B0 → K*0 μ+ μ- are studied by using an integrated luminosity of 0.37 fb(-1) of data collected with the LHCb detector. The forward-backward asymmetry of the muons, A(FB), the fraction of longitudinal polarization, F(L), and the partial branching fraction dB/dq2 are determined as a function of the dimuon invariant mass. The measurements are in good agreement with the standard model predictions and are the most precise to date. In the dimuon invariant mass squared range 1.00-6.00 GeV2/c4, the results are A(FB)=-0.06(-0.14)(+0.13)±0.04, F(L)=0.55±0.10±0.03, and dB/dq2=(0.42±0.06±0.03)×10(-7) c4/GeV2. In each case, the first error is statistical and the second systematic.     

First observation of the decays B(0) → D(+)K(-)π(+)π(-) and B(-) → D(0)K(-)π(+)π(-)

First observations of the Cabibbo-suppressed decays B(0) → D(+)K(-)π(+)π(-) and B(-) → D(0)K(-)π(+)π(-) are reported using 35 pb(-1) of data collected with the LHCb detector. Their branching fractions are measured with respect to the corresponding Cabibbo-favored decays, from which we obtain B(B(0) → D(+)K(-)π(+)π(-))/B(B(0) → D(+)π(-)π(+)π(-))=(5.9±1.1±0.5)×10(-2) and B(B(-) → D(0)K(-)π(+)π(-))/B(B(-) → D(0)π(-)π(+)π(-))=(9.4±1.3±0.9)×10(-2), where the uncertainties are statistical and systematic, respectively. The B(-) → D(0)K(-)π(+)π(-) decay is particularly interesting, as it can be used in a similar way to B(-) → D(0)K(-) to measure the Cabibbo-Kobayashi-Maskawa phase γ.     

First observation of B(s)(0) → J/ψη and B(s)(0) → J/ψη'

We report first observations of B(s)(0) → J/ψη and B(s)(0) → J/ψη'. The results are obtained from 121.4 fb(-1) of data collected at the Υ(5S) resonance with the Belle detector at the KEKB e+ e- collider. We obtain the branching fractions B(B(s)(0) → J/ψη)=[5.10±0.50(stat)±0.25(syst)(-0.79)(+1.14)(N(B(s)(*) B(s)(*))]×10(-4), and B(B(s)(0) → J/ψη')=[3.71±0.61(stat)±0.18(syst)(-0.57)(+0.83)(N(B(s)(*) B(s)(*))]×10(-4). The ratio of the two branching fractions is measured to be (B(B(s) → J/ψη'))/(B(B(s) → J/ψη))=0.73±0.14(stat)±0.02(syst).     

Determination of the branching ratiosΓ(K L→3π0)/Γ(K L→π+ - 0) andΓ(K L→3π0)/Γ(K L→πev)

Improved branching ratios were measured for theK _L3⁰ decay in a neutral beam at the CERN SPS with the NA31 detector:

Superallowed 0+ → 0+ beta-decay and CKM unitarity

Precise measurements of the ft-values for superallowed nuclear β-decay yield results that support conservation of the weak vector current but violate the unitarity of the Cabibbo-Kobayashi-Maskawa matrix by more than two standard deviations. This apparent violation of the Standard Model has led to considerable theoretical and experimental activity largely focussed on reducing uncertainties in the small correction terms that account for charge-dependent nuclear effects. This activity is outlined and the prospects for future sharpening of the unitarity test are assessed. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: hardy@comp.tamu.edu     

A test of CPT symmetry in K0 vs (K-)0→π+π-π0 decays

I show that the CP-violating asymmetry in K0 vs K-0→π+π-π0 decays differs from that in KL→π+π-,KL→π0π0 or the semileptonic KL transitions,if there exists CPT violation in K0-K-0 mixing.A delicate measurement of this difference at a super flavor factory(e.g.,the φ factory)will provide us with a robust test of CPT symmetry in the neutral kaon system.     

Study of scalar meson a0(980) from B→a0(980)π decays

In this paper, we calculate the branching ratios and the direct CP-violating asymmetries for decays B0 →a00(980)π0, a0+(980)π-, a0-(980)π and B- →a00(980)π-, a0-(980)π0 by employing the perturbative QCD (pQCD) factorization approach at the leading order. We found that (a) the pQCD predictions for the branching ratios are around (0.4 - 2.8) × 10-6, consistent with currently available experimental upper limits; (b) the CP asymmetries of B0→ao(980)π0 and B-→a0-(980)π0 decays can be large, about (70-80)% for α = 100°.     

Study of scalar meson a_0(980) from B→a_0(980)π decays

In this paper,we calculate the branching ratios and the direct CP-violating asymmetries for decays B0 →a00(980)π0,a0+(980)π-,a0-(980)π+ and B- →a00(980)π-,a0-(980)π0 by employing the perturbative QCD(pQCD) factorization approach at the leading order.We found that(a) the pQCD predictions for the branching ratios are around(0.4-2.8)×10-6,consistent with currently available experimental upper limits;(b) the CP asymmetries of B0 →a00(980)π0 and B- →a0-(980)π0 decays can be large,about(70-80)% for α=100-.     

Effects of the littlest Higgs model on the process e~+ e~- → μ~+ μ~- at a Z~0-factory

We investigate the possibilities of finding the effects of the littlest Higgs (LH) model on the process e + e - →μ + μ - at the leadingorder at a possible Z 0-factory.We study the impacts of the LH model on the observables,such as,the total cross section,the distribution of the transverse momentum of μ-,and the forward-backward charge asymmetry of μin polarized and unpolarized electron-positron collision modes.Besides,we analyze the relations between the observables and the LH model parameters,and discuss the observables of process e + e→μ + μ-in different incoming electron-positron polarization modes.We conclude that one could observe the effects contributed by the LH model on the process e + e-→μ + μin a reasonable parameter space,or might put more stringent constraints on the LH parameters in the future experiments at the possible Z 0-factory.     

Final state interaction effects in the B + → D + K 0 decay

The exclusive decay of B ⁺ → D ⁺ K ⁰ is calculated by the QCD factorization method (QCDF) and final state interaction (FSI). First, the B ⁺ → D ⁺ K ⁰ decay is calculated via QCDF method. The result that is found by using the QCDF method is less than the experimental result. So FSI is considered to solve the B ⁺ → D ⁺ K ⁰ decay. For this decay, the D _s ⁺ π⁰, D _s ⁺ *ρ⁰, D _s ⁺ *? via the exchange of \(\bar K^0\) , \(\bar K^{0*} \) , D ^?, and D ^?* mesons are chosen for the intermediate states. The above intermediate states are calculated by using the QCDF method. In the FSI effects, the results of our calculations depend on η as the phenomenological parameter. The range of this parameter is selected from 2 to 2.4. It is found that if η = 2.4 is selected, the numbers of the branching ratio are placed in the experimental range. The experimental branching ratio of this decay is less than 2.9 × 10^?6 and our results calculated by QCDF and FSI are (0.16 ± 0.04) × 10^?6 and (2.8 ± 0.09) × 10^?6, respectively.     

χc0→B(-B)MM衰变中的重子共振态

基于SU(3)对称性研究了χc0的遍举多体衰变χc0→B(-B)MM(B:重子,M:介子),通过同位旋耦合常数构造了χc0→B(-B)→B(-B)MM衰变的跃迁振幅.基于这些跃迁振幅,发现N*共振态对χc0→B(-B)ππ的贡献相对较大,这个衰变道可以在实验上用来研究N*共振态.     

Study of scalar meson f 0(980) from B→f 0(980)K * decays

We show how parton distributions unintegrated over the parton transverse momentum, k _t , may be generated, at NLO accuracy, from the known integrated (DGLAP-evolved) parton densities determined from global data analyses. A few numerical examples are given, which demonstrate that sufficient accuracy is obtained by keeping only the LO splitting functions together with the NLO integrated parton densities. However, it is important to keep the precise kinematics of the process, by taking the scale to be the virtuality rather than the transverse momentum, in order to be consistent with the calculation of the NLO splitting functions.     

Study of f 0(980) and f 0(1500) from B s →f 0(980)π,f 0(1500)π decays

In this paper, we analyze the scalar mesons f ₀(980) and f ₀(1500) from the decays $\bar{B}^{0}_{s}\to f_{0}(980)\pi^{0},\allowbreak f_{0}(1500)\pi^{0}$ within Perturbative QCD approach. From the leading-order calculations, we find that (a) in the allowed mixing angle ranges, the branching ratio of $\bar{B}^{0}_{s}\to f_{0}(980)\pi^{0}$ is about (1.0～1.6)×10^?7, which is smaller than that of $\bar{B}^{0}_{s}\to f_{0}(980)K^{0}$ (the difference is a few times even one order); (b) the decay $\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0}$ is better to distinguish between the lowest lying state or the first excited state for f ₀(1500), because the branching ratios for two scenarios have about one-order difference in most of the mixing angle ranges; and (c) the direct CP asymmetries of $\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0}$ for two scenarios also exists great difference. In scenario II, the variation range of the value ${\mathcal{A}}^{\mathrm{dir}}_{CP}(\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0})$ according to the mixing angle in scenario II is very small, except for the values for mixing angles near 90° or 270°, while the variation range of ${\mathcal{A}}^{\mathrm{dir}}_{CP}(\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0})$ in scenario I is very large. Compared with the future data for the decay $\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0}$ , it is easy to determine the nature of the scalar meson f ₀(1500).     

Dynamics of the CH4+ O(~3 P) → CH_3(ν= 0) + OH(■= 0) reaction

The dynamics of the ground-state reaction of CH_4+ O(~3P) → CH_3(ν = 0) + OH( ν= 0) have attracted a great deal of attention both theoretically and experimentally. This rapid communication represents extensive quasi-classical trajectory calculations of the vibrational distributions on a unique full-dimensional ab initio potential energy surface for the title reaction, at the collision energy of relevance to previous crossed molecular beam experiments. The surface is constructed using the all electrons coupled-cluster singles and doubles approach plus quasi-perturbative triple excitations with optimized basis sets. A modified Shepard interpolation method is also employed for the construction. Good agreement between our calculations and the available experimental results has been achieved, opening the door for accurate dynamics on this surface.     

The A+B→0 diffusion-limited reaction with correlated initial condition

We show some inaccuracies in recent arguments claiming that in the long-time limit the initially correlated A+B0 diffusion-limited reaction can be faster than the A+A0 one. With the errors corrected, these arguments seem to confirm the former theory of Toussant and Wilczek according to which the global rate of both reactions should ultimately be the same. This hypothesis is also supported by our numerical simulations of a two-dimensional lattice system.     

The diffusion-limited reaction A+B→0 on a fractal substrate

We show in this paper how the segregation of reactants in the diffusion-limited reaction A+B0 on a fractal substrate arises. For spectral dimensions d_s 2 we obtain segregation controlled by the source and/or the intrinsic lifetime of the particles.