D+→η(')l+νl semileptonic decays in light-cone sum rules

We calculate the D→η transition form factor in light-cone sum rules by taking improved current correlators to avoid the pollution from the twist-3 wave function. We get consistent results of the D<'+> →η<'(')> l<'+>ν<,l> decays with the experimental data. By comparing the difference between the results of the branching ratios of D+ →η<'(')>l<'+>ν<,l> from a two-pole parameterization model and from a BZ parameterization model, we find that the two-pole model and the BZ model are comparably believable. One way is supposed for the determination of the η-η' mixing angle from the dependence of the branching ratios of D<'+> →η<'(')>l<'+>ν<,l> decays on the η-η' mixing angle.     

Absolute branching fraction measurements of exclusive D0 semileptonic decays

With the first data sample collected by the CLEO-c detector at the psi(3770) resonance we have studied four exclusive semileptonic decays of the D0 meson. Our results include the first observation and absolute branching fraction measurement for D0 --> p-e+ve and improved measurements of the absolute branching fractions for D0 decays to K-e+ve, pi-e+ve, and K*-e+ve.     

Recent results from NA48/2

Recent results on radiative K± decays from the NA48/2 experiment are reported.From the full NA48/2 data set,about a million K±→π±π0γ decays were reconstructed.Based on this sample,the first measurement of the interference between direct photon emission and inner bremsstrahlung in K±→π±π0γ decays was performed.Stringent limits on CP violation in this decay were also set.In addition,a precise measurement of the branching fraction of K±→π±γγ is presented.This measurement was based on a data sample of more than 1000 event candidates.Also the related decay K±→π±e+e-γ has first been observed.Results of the measurement of the decay rate and the decay parameter c are summarized.     

Ds1(2536)+ decays and the structure of P-wave charmed strange mesons

We calculate the D s 1 (2536) + decays into D*K channels,including the decay D s 1 (2536) + → D + π-K + through a virtual D*0 in a constituent quark model.Widths and S/D amplitudes ratio are in agreement with the recent Belle and BABAR data,being the results sensitive to 1 P 1 and 3 P 1 mixture.     

Semileptonic Decays of Bc Meson to a P—Wave Charmonium State χc or hc

The semileptonic decays of meson Bc to a P-wave charmonium state χc(3PJ) or hc(1P1)are computed.The results show that the decays are sizable so they are accessible in Tevatron and LHC,especially,with the detectors LHCB and BTeV in the foreseeable future,and of them,the one to the 1P1 charmonium state potentially offers us a novel window to see the unconfirmed hc particle.In addition,it is pointed out that since the two charmonium radiative decays χc (3P1,2)→J/ψ γ have sizable branching ratios,the cascade decays of the concerned decays and the charmonium radiative decays may affect the result of observing Bc meson through the semileptonic decays Bc→J/ψ l vl substantially.     

Measurement of the wrong-sign decays D0 --> K+ pi- pi0 and D0 --> K+ pi- pi+ pi-, and search for CP violation

Using 281 fb-1 of data from the Belle experiment recorded at or near the (4S) resonance, we have measured the rates of the "wrong-sign" decays D0 --> K+ pi- pi0 and D0 --> K+ pi- pi+ pi- relative to those of the Cabibbo-favored decays D0 --> K- pi+ pi0 and D0 --> K- pi+ pi+ pi-. These wrong-sign decays proceed via a doubly Cabibbo-suppressed amplitude or via D0-D0 mixing; the latter has not yet been observed. We obtain R(WS)(K pi pi0) = [0.229 +/- 0.015(stat)(+0.013)(-0.009)(syst)]% and R(WS)(K3pi) = [0.320 +/- 0.018(stat)(+0.018)(0.013)(syst)]%. The CP asymmetries are measured to be -0.006 +/- 0.053 and -0.018 +/- 0.044 for the K+ pi- pi0 and K+ pi- pi+ pi- final states, respectively.     

Time modulation of the beta{+}-decay rate of H-like 140Pr58+ ions

Recent experimental data at GSI on the rates of the number of daughter ions, produced by the nuclear K-shell electron capture (EC) decays of the H-like ions 140Pr58+ and 142Pm60+, suggest that they are modulated in time with periods T_{EC} approximately 7 sec and amplitudes a_{EC} approximately 0.20. Since it is known that these ions are unstable also under the nuclear positron (beta;{+}) decays, we study a possible time dependence of the nuclear beta;{+}-decay rate of the H-like 140Pr58+ ion. We show that the time dependence of the beta;{+}-decay rate of the H-like 140Pr58+ ion as well as any H-like heavy ions cannot be observed.     

Measurement of the Time-Dependent CP Asymmetry in B;{0}-->D_{CP};{(*)}h;{0} Decays

We report a measurement of the time-dependent CP-asymmetry parameters S and C in color-suppressed B{0}-->D{(*)0}h{0} decays, where h{0} is a pi{0}, eta, or omega meson, and the decays to one of the CP eigenstates K+K-, K{S}{0}pi{0}, or K{S}{0}omega. The data sample consists of 383 x 10{6} Upsilon(4S)-->BB decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. The results are S=-0.56+/-0.23+/-0.05 and C=-0.23+/-0.16+/-0.04, where the first error is statistical and the second is systematic.     

Rare semileptonic decays of heavy mesons in the heavy quark limit

We study the branching ratios of D+→D0e+ν,DS+→D0e+ν,BS0→B+e-ν,DS+→D+e-e+ and BS0→B0e-e+ rare semileptonic decay processes,which are induced by decays of light quarks,the heavy quarks remain unchanged.The branching ratios of these decay processes are estimated in the heavy quark limit and with SU(3) flavor symmetry.We find that the decay rates are very tiny in the framework of the Standard Model.We also estimate the sensitivities of the measurements of these rare decays at the future experiments,such as BES-Ⅲ,super-B and LHC-b.Observations of these decays may shed some light on new physics beyond the standard model.     

Improved constraints on D0-D0 mixing in D0 --> K+ pi- decays from the Belle detector

We report the results of a search for D0-D0 mixing in D0 --> K+ pi- decays based on 400 fb(-1) of data accumulated by the Belle detector at KEKB. Both assuming CP conservation and allowing for CP violation, we fit the decay-time distribution for the mixing parameters x and y, as well as for the parameter R(D), the ratio of doubly Cabibbo-suppressed decays to Cabibbo-favored decays. The 95% confidence level region in the (x'2,y') plane is obtained using a frequentist method. Assuming CP conservation, we find x'2 < 0.72 x 10(-3) and -9.9 x 10(-3) < y' < 6.8 x 10(-3) at the 95% confidence level; these are the most stringent constraints on the mixing parameters to date. The no-mixing point (0,0) has a confidence level of 3.9%. Assuming no mixing, we measure R(D) = (0.377 +/- 0.008 +/- 0.005)%.     

Zweig's rule violation,SU(3) character of the decay of the new particles,and pole dominance picture

The decays ψ′ → ψππ and ψ → ω? are studied in the framework of Zweig Rule violation via SU(4) pole dominance. The SU(3) character of the decay of the ψ is discussed in the same model. Using results of the purely hadronic decays, the cascade transition rates ψ′ → ?_c + γ and ?_carψ + γ are calculated and compared to recent experimental data.     

Weak radiative hyperon decays in the pole model

We compute the parity conserving and parity violating amplitudes of the weak radiative hyperon decays in a pole model which includes negative parity intermediate states. The matrix elements are determined from experimentally known quantities and also evaluated in a nonrelativistic quark model. We find good numerical agreement with the data for the decay Σ⁺→P+γ and obtain predictions for the other decays where experimental information has been scarce up to now.     

Measurement of the ratio of B+ and B0 meson lifetimes

The ratio of the B+ and B0 meson lifetimes was measured using data collected in 2002-2004 by the D0 experiment in Run II of the Fermilab Tevatron Collider. These mesons were reconstructed in B-->mu(+)nuD(*-)X decays, which are dominated by B0 and B-->mu(+)nuD 0X decays, which are dominated by B+. The ratio of lifetimes is measured to be tau(+)/tau(0)=1.080+/-0.016(stat)+/-0.014(syst).     

Search for invisible decays of eta and eta' in J/psi --> phi eta and phi eta'

Using a data sample of 58 x 10(6) J/psi decays collected with the Beijing Spectrometer II detector at the Beijing Electron Positron Collider, searches for invisible decays of eta and eta' in J/psi to phi eta and phi eta' are performed. The phi signals, which are reconstructed in K+K- final states, are used to tag the eta and eta' decays. No signals are found for the invisible decays of either eta or eta', and upper limits at the 90% confidence level are determined to be 1.65 x 10(-3) for the ratio B(eta-->invisible)/B(eta --> gamma gamma) and 6.69 x 10(-2) for B(eta' --> invisible)/B(eta' --> gammagamma). These are the first searches for eta and eta' decays into invisible final states.     

Absolute branching fraction measurements of exclusive D+ semileptonic decays

Using data collected at the psi(3770) resonance with the CLEO-c detector at the Cornell e+e- storage ring, we present improved measurements of the absolute branching fractions of D+decays to K0e+ve, pi0e+ve, K*0e+ve, and p0e+ve, and the first observation and absolute branching fraction measurement of D+ --> omega e+ve. We also report the most precise tests to date of isospin invariance in semileptonic D0 and D+ decays.     

Study of the Standard Model Higgs Boson in the ATLAS and CMS Experiments at the LHC

Physics of Atomic Nuclei - Recent results on Higgs boson production and decays in the ATLAS and CMS experiments at the LHC are reviewed. These results are based on data accumulated from 2015 to...     

Does the HyperCP evidence for the decay Sigma+ -->pmu+mu- indicate a light pseudoscalar Higgs boson?

The HyperCP Collaboration has observed three events for the decay Sigma+ -->p mu+mu- which may be interpreted as a new particle of mass 214.3 MeV. However, existing data from kaon and B-meson decays provide stringent constraints on the construction of models that support this interpretation. In this Letter we show that the "HyperCP particle" can be identified with the light pseudoscalar Higgs boson in the next-to-minimal supersymmetric standard model, the A10. In this model there are regions of parameter space where the A10 can satisfy all the existing constraints from kaon and B-meson decays and mediate Sigma+ -->p mu+mu- at a level consistent with the HyperCP observation.     

Transverse momentum distributions of neutral pions from nuclear collisions at 200 AGeV

New results on transverse mass spectra of neutral pions measured at central rapidity are presented for impact parameter selected 200 GeV S + S and S + Au collisions. The distributions cover more than 8 orders of magnitude in cross section over the range . Detailed comparisons to results from pp collisions are made. The spectra from all systems show a clear power-law like shape with similar curvature. Collisions of S + Au exhibit a larger mean transverse momentum than pp increasing with centrality. Predictions of string models and by hydrodynamic approaches including collective expansion and decays of short lived resonances are compared to the data and the implications are discussed. Received: 10 March 1998 / Revised version: 22 May 1998 / Published online: 12 August 1998     

Evidence for the rare decay B-->K*l+l- and measurement of the B-->Kl+l- branching fraction

We present evidence for the flavor-changing neutral current decay B-->K*l+l- and a measurement of the branching fraction for the related process B-->K l+l-, where l+l- is either an epsilon+epsilon- or a mu+mu- pair. These decays are highly suppressed in the standard model, and they are sensitive to contributions from new particles in the intermediate state. The data sample comprises 123 x 10(6) Upsilon(4S)-->B(-)B decays collected with the BABAR detector at the SLAC PEP-II epsilon+epsilon- storage ring. Averaging over K(*) isospin and lepton flavor, we obtain the branching fractions B(B-->Kl+l-)=(0.65(+0.14)(-0.13)+/-0.04)x10(-6) and B(B-->K*l+l-)=(0.88(+0.33)(-0.29)+/-0.10)x10(-6), where the uncertainties are statistical and systematic, respectively. The significance of the B-->Kl+l- signal is over 8sigma, while for B-->K*l+l- it is 3.3sigma.     

B→πη('), η(')η(') decays and NLO contributions in the pQCD approach

By employing the perturbative QCD (pQCD) factorization approach, we calculate the full leading and the partial next-to-leading order (NLO) contributions to the seven B→πη(') and η(')η(') decays. For B+B→π+η(') decays, the pQCD predictions for their decay rates agree very well with the data after the inclusion of the small NLO contributions. For neutral decays, the pQCD predictions are also consistent with the experimental upper limits and can be tested by the LHC experiments. The measured value of ACPdir(π±η)=-19±7% can also be accommodated by the pQCD approach.