We report the observation of a near-threshold enhancement in the omega-J/psi invariant mass distribution for exclusive B-->K omega J/psi decays. The results are obtained from a 253 fb-1 data sample that contains 275 million BB-bar meson pairs that were collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e+e- collider. The statistical significance of the omega-J/psi mass enhancement is estimated to be greater than 8 sigma.
The exclusive electroproduction of omega mesons, ep -> e omega p, has been studied in the kinematic range 3<Q^2<20 GeV^2, 40<W<120 GeV and |t|<0.6 GeV^2 with the ZEUS detector at HERA using an integrated luminosity of 37.7 pb^{-1}. The omega mesons were identified via the decay omega -> pi^+pi^-pi^0. The exclusive (ep -> e omega p) cross section in the above kinematic region is 0.108 +- 0.014(stat.) +- 0.026(syst.) nb. The reaction ep -> e phi p, phi -> pi^+pi^-pi^0, has also been measured. The cross sections, as well as the cross-section ratios omega/rho and omega/phi, are presented as a func…
The CLEO Collaboration has made the first observations of hadronic transitions among bottomonium (b-bbar) states other than the dipion transitions among upsns states. In our study of Y(3S) decays, we find a significant signal for Y(3S) -> gamma omega Y(1S) that is consistent with radiative decays Y(3S) -> gamma chi_b1,2(2P), followed by chi_b1,2(2P) -> omega Y(1S). The branching ratios we obtain are B(chi_b1(2P) -> omega Y(1S)) = (1.63 +0.35-0.31 +0.16-0.15)% and B(chi_b2(2P) -> omega Y(1S)) = (1.10 +0.32-0.28 +0.11-0.10)%, in which the first error is statistical and the second is systematic.
The CLEO Collaboration has observed the first hadronic transition among bottomonium (b bbar) states other than the dipion transitions among vector states, Upsilon(nS) -> pi pi Upsilon(mS). In our study of Upsilon(3S) decays, we find a significant signal for Upsilon(3S) -> gamma omega Upsilon(1S) that is consistent with radiative decays Upsilon(3S) -> gamma chi_{b 1,2}(2P), followed by chi_{b 1,2} -> omega Upsilon(1S). The branching ratios we obtain are Br(chi_{b1} -> omega Upsilon(1S) = 1.63 (+0.35 -0.31) (+0.16 -0.15) % and Br(chi_{b2} -> omega Upsilon(1S) = 1.10 (+0.32 -0.28) (+0.11 - 0.10)%…
A search for the exclusive radiative decays B->rho(770) gamma and B^0->omega(782) gamma is performed on a sample of 84 million BB-bar events collected by the BABAR detector at the PEP-II asymmetric e^+e^- collider. No significant signal is seen in any of the channels. We set preliminary upper limits of BR[B^0->rho^0 gamma]< 1.4 times 10^{-6}, BR[B^+ -> rho^+ gamma] < 2.3 times 10^{-6} and BR[B^0 -> omega gamma]< 1.2 times 10^{-6} at 90% Confidence Level. Combining these into a single limit on the generic process B-> rho gamma, we find the preliminary limit BR[B -> rho gamma]<1.9 times 10^{-6},…
The exclusive omega electroproduction off the proton was studied in a large kinematical domain above the nucleon resonance region and for the highest possible photon virtuality (Q2) with the 5.75 GeV beam at CEBAF and the CLAS spectrometer. Cross sections were measured up to large values of the four-momentum transfer (-t < 2.7 GeV2) to the proton. The contributions of the interference terms sigma_TT and sigma_TL to the cross sections, as well as an analysis of the omega spin density matrix, indicate that helicity is not conserved in this process. The t-channel pi0 exchange, or more generally t…
The helicity density matrix elements rho[00] of rho(770)+- and omega(782) mesons produced in Z decays have been measured using the OPAL detector at LEP. Over the measured meson energy range, the values are compatible with 1/3, corresponding to a statistical mix of helicity -1, 0 and +1 states. For the highest accessible scaled energy range 0.3 < x_E < 0.6, the measured rho[00] values of the rho(770)+- and the omega are 0.373 +- 0.052 and 0.142 +- 0.114, respectively. These results are compared to measurements of other vector mesons.
We report measurements of branching fractions for psi(2S) decays into omega pi pi, b1 pi,omega f2(1270),omega KK, omega p pbar, phi pi pi, phi f0(980),phi KK, and an upper limit for phi p pbar final states based on a data sample of 4 X 10^6 psi(2S) events collected with the BESI detector at the Beijing Electron-Positron Collider. The branching fractions for b1 pi and omega f2(1270) update previous BES results, while those for other decay modes are first measurements. The ratios of psi(2S)and J/psi branching fractions are smaller than what is expected from the 12% rule by a factor of five for o…
Using data recorded by the CLEO III detector at CESR, we report on the first measurements of the branching fractions for decays of the Lambda_c^+ charmed baryon into (Lambda pi+ pi+ pi- pi0) and (Lambda omega pi+). All rates are measured with respect to the p K- pi+ decay mode. The relative branching fractions are 0.39 +- 0.09(stat.) +- 0.09(syst.) and 0.24 +- 0.06(stat.) +- 0.06(syst.) for the (Lambda pi+ pi+ pi- pi0) and (Lambda omega pi+) modes, respectively. The data also suggest decays of the Lambda_c^+ via (Lambda eta pi+, eta --> pi+ pi- pi0) with a rate which is consistent with previou…
The detection efficiency correction for the particle identification and kinematic fit selection criteria is investigated for the branching fraciton measurements in the psi(2S) decays into omega pi pi, b1 pi, omega f2(1270), omega K K, omega p pbar, phi pi pi, phi f0(980), phi K K and phi p pbar final states using 4 millions psi(2S) data sample coolected at BEPC/BES. Based on the corrected efficiencies, the preliminary results of these decay channels have been obtained, and the "12%" rule predicted by perturbative QCD theory tested.
We present results of searches for B-meson decays to charmless final states that include a K*, rho, omega, or phi meson accompanied by a second meson. Using the entire data sample of 9.7 million BBbar pairs collected with the CLEO II and CLEO II.V detectors, we observe a signal for the decay B+ -> omega pi+, and measure a branching fraction of B(B+ -> omega pi+) = (11.3^{+3.3}_{-2.9} \pm 1.5) \times 10^{-6}. We also see evidence for the decay B0 -> omega K0, and set limits for the decays B0 -> rho0 pi0 and B0 -> K*0 pi0. In addition to these new results, we also summarize previous CLEO results…
The search for exclusive hadronic vector boson decays is an ongoing part of the LHC programme where, to date, no such decays have been observed. In addition to the intrinsic interest in the branching ratios, there is potential for a measurement of the $W$ boson mass quite distinct from the usual methods. The radiative decay modes offer good potential channels for this search; however, we highlight three issues with it not previously discussed: particle misidentification, partial reconstruction and the impact of interference with QCD. These issues cause shifts in the peak position of tens or hu…
The inclusive production of the omega(782) vector meson in hadronic Z decays is measured and compared to model predictions. The analysis is based on 4 million hadronic Z decays recorded by the ALEPH detector between 1991 and 1995. The production rate for x_p = p_meson/p_beam > 0.05 is measured in the omega -> pi^+ pi^- pi^0 decay mode and found to be 0.585 +- 0.019_stat +- 0.033_sys per event. Inclusive eta meson production is also measured in the same decay channel for x_p > 0.10, obtaining 0.355 +- 0.011_stat +- 0.024_sys per event. The branching ratio for omega -> mu^+ mu^- is investigated.…
We present a new result from Belle and many new results from BABAR for rare hadronic B decays. These include measurements of decays involving baryons, a Dalitz plot analysis of the three-charged-kaon system, many new results for B decays to eta'X and omegaX, and a limit for the decay B-> a_1 rho. Measurements of the vector-vector decays B->rhoKstar and B->omegaKstar are helping to understand the value of the longitudinal polarization fraction for these B->VV decays.
Using data taken with the CLEO III detector, 1.09 fb-1 at Upsilon(1S), and 1.28 fb-1 at Upsilon(2S), branching fractions have been measured for the first time for exclusive decays of each resonance into one hundred different final states consisting of 4 to 10 light hadrons, pions, kaons, and protons. Significant strength is found in 73 decay modes of Upsilon(1S) and 17 decay modes of Upsilon(2S), with branching fractions ranging from 0.3x10^-5 to 110x10^-5. Upper limits at 90% confidence level are presented for the other decay modes.
We present recent results from the Belle experiment on rare hadronic B meson decays. The results are based on a 78 fb^{-1} data sample and consist of branching fractions, CP asymmetries, and polarization amplitudes. The decays studied include two-body pseudoscalar-pseudoscalar final states (B -> pi pi, K pi, KK, and D^0 K^\pm); pseudoscalar-vector final states (B -> omega pi, omega K, and phi K); and vector-vector final states (B -> phi K* and rho^+ rho^0).
Using data accumulated with the CLEO detector corresponding to an integrated luminosity of 5.46 1/pb on the peak of the psi(2S) and 20.46 1/pb at E_CM=3.67 GeV, we report preliminary branching fraction measurements for seven new decay modes of the psi(2S) (eta 3pi, eta' 3pi, 2(K+ K-), p pbar K+ K-, Lambda Lambdabar pi+ pi-, Lambda pbar K+, and Lambda pbar K+ pi+ pi-) and more precise measurements of nine previously measured modes (2(pi+pi-), 2(pi+pi-) pi0, omega pi+pi-, K+ K- pi+ pi-, phi pi+ pi-, omega K+ K-, phi K+ K-, p pbar pi+ pi-, and Lambda Lambdabar). We also include a study of omega p…
We report results of searches for charmless hadronic B meson decays to pseudoscalar(pi^+-,K^+-,Pi^0 or Ks^0)-vector(Rho, K* or Omega) final states. Using 9.7 million BBbar pairs collected with the CLEO detector, we report first observation of B^- --> Pi^-Rho^0, B^0 --> Pi^+-Rho^-+ and B^- --> Pi^-Omega, which are expected to be dominated by hadronic b --> u transitions. The measured branching fractions are (10.4+3.3-3.4+-2.1)x10^-6, (27.6+8.4-7.4+-4.2)x10^-6 and (11.3+3.3-2.9+-1.4)x10^-6, respectively. Branching fraction upper limits are set for all the other decay modes investigated.
My report consists of two parts: (1). Using samples of 102 million $Υ(1S)$ and 158 million $Υ(2S)$ events at Belle, we study 17 exclusive hadronic decays of these two bottomonium resonances to some Vector-Pseudoscalar (VP), Vector-Tensor (VT) and Axial-vector-Pseudoscalar (AP) processes and their final states. Branching fractions are measured for all the processes. The ratios of the branching fractions of $Υ(2S)$ and $Υ(1S)$ decays into the same final state are used to test a perturbative QCD (pQCD) prediction for OZI-suppressed bottomonium decays. (2). Using data samples of 89 fb$^{-1}$, 703 …
We present measurements of branching fraction, polarization and charge asymmetry in charmless hadronic B decays with eta, eta', omega, and b_1 in the final state. All the results use the final BABAR dataset.
We have searched for two-body charmless hadronic decays of $B$ mesons. Final states include $ππ$, $K π$, and $KK$ with both charged and neutral kaons and pions; $πρ$, $K ρ$, and $K^*π$; and $Kϕ$, $ K^*ϕ$, and $ϕϕ$. The data used in this analysis consist of 2.6~million $B\bar{B}$~pairs produced at the $Υ(4S)$ taken with the CLEO-II detector at the Cornell Electron Storage Ring (CESR). We measure the branching fraction of the sum of $B^0 \rightarrow π^+π^-$ and $B^0 \rightarrow K^+π^-$ to be $(1.8^{+0.6+0.2}_{-0.5-0.3}\pm0.2) \times 10^{-5}$. In addition, we place upper limits on individual bran…
We present preliminary results of a search for $B\to X_dγ$ decays with a hadronic mass 1.0 GeV/$c^2<M(X_d)<$1.8 GeV/$c^2$. We consider seven final states with up to four charged pions and one neutral pion or $η$, which correspond to about 50% of the total $X_d$ fragmentation in this mass range. Based on a sample of 383 million $B\bar{B}$ events collected by the BaBar experiment at PEP-II, we measure a partial branching fraction $\sum\nolimits^{7}_{X_d=1}{{\ensuremath{\cal B}\xspace}}(B\to X_dγ)|_{(1.0{GeV}/c^2 <M(X_d)<1.8 {GeV}/c^2)}= (3.1\pm0.9 ^{+0.6}_{-0.5} \pm0.5)\cdot 10^{-6},$ where the …
A measurement of the spin of the Omega^- hyperon produced through the exclusive process Xi_c^0 --> Omega^- K^+ is presented using a total integrated luminosity of 116 fb^-1 recorded with the BABAR detector at the e^+ e^- asymmetric-energy B-Factory at SLAC. Under the assumption that the Xi_c^0 has spin 1/2, the angular distribution of the Lambda from Omega^- --> Lambda K^- decay is inconsistent with all half-integer Omega^- spin values other than 3/2. Lower statistics data for the process Omega_c^0 --> Omega^- pi^+ from a 230 fb^-1 sample are also found to be consistent with Omega^- spin 3/2. …
The measurement of exclusive $e^+e^-$ to hadrons processes is a significant part of the physics program of $BABAR$ experiment, aimed to improve the calculation of the hadronic contribution to the muon $g-2$ and to study the intermediate dynamics of the processes. We present the most recent results obtained by using the full data set of about 470\,fb$^{-1}$ collected by the BABAR detector at the PEP-II $e^+e^-$ collider at a center-of-mass energy of about 10.6 GeV. In particular, we report the results on $e^+e^-$ annihilation into six- and seven-pion final states. The study of the very rich dyn…
Using $2.93\,\rm fb^{-1}$ of $e^+e^-$ collision data taken at a center-of-mass energy of 3.773\,GeV with the BESIII detector, we report the first measurements of the absolute branching fractions of fourteen hadronic $D^{0(+)}$ decays to exclusive final states with an $η$, e.g., $D^0\to K^-π^+η$, $K^0_Sπ^0η$, $K^+K^-η$, $K^0_SK^0_Sη$, $K^-π^+π^0η$, $K^0_Sπ^+π^-η$, $K^0_Sπ^0π^0η$, and $π^+π^-π^0η$; $D^+\to K^0_Sπ^+η$, $K^0_SK^+η$, $K^-π^+π^+η$, $K^0_Sπ^+π^0η$, $π^+π^+π^-η$, and $π^+π^0π^0η$. Among these decays, the $D^0\to K^-π^+η$ and $D^+\to K^0_Sπ^+η$ decays have the largest branching fractio…
Using data accumulated with the CLEO detector corresponding to an integrated luminosity of 5.63 pb^-1 on the peak of the psi(2S) and 20.70 pb^-1 continuum at 3.67 GeV, we report first measurements of the branching fractions for the following 13 decay modes of the psi(2S): eta 3pi, eta^\prime 3pi, rho K^+K^-, K^+K^-pi^+pi^-pi^0, 2(K^+K^-), 2(K^+K^-)pi^0, rho p \bar p, p \bar p pi^+pi^-pi^0, eta p \bar p, p \bar p K^+K^-, Lambda \bar Lambda pi^+pi^-, Lambda \bar p K^+, Lambda \bar p K^+pi^+pi^-, and more precise measurements of 8 previously measured modes: 2(pi^+pi^-), rho pi^+pi^-, 2(pi^+pi^-)p…
We report on a search for the exclusive two-body charmless hadronic B meson decays B-> eta' rho, B-> eta' K*, B-> eta' phi, B-> eta' omega and B->eta' eta('). The results are obtained from a data sample containing 535 x 10^6 BBbar pairs that were collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider. We find no significant signals and report upper limits in the range 0.5-6.5 x 10^{-6} for all of the above decays.
We perform a global analysis of exclusive hadronic tau decays into one and two mesons using the low-energy limit of the Standard Model Effective Field Theory up to dimension six, assuming left-handed neutrinos. A controlled theoretical input on the Standard Model hadronic form factors, based on chiral symmetry, dispersion relations, data and asymptotic QCD properties, has allowed us to set bounds on the New Physics effective couplings using the present experimental data. Our results highlight the importance of semileptonic $τ$ decays in complementing the traditional low-energy probes, such nuc…
We have fully reconstructed decays of both B0 and B- Mesons into final states containing either D, D*, D**, Psi, Psi', or Chi_{c1} mesons. This allows us to obtain new results on many physics topics including branching ratios, tests of the factorization hypothesis, color suppression, resonant substructure, and the B- - B0 mass difference.
The exclusive production of axionlike particles (ALPs) by gluon -- induced interactions is investigated in this exploratory study considering $pp$ and $PbPb$ collisions for the energies of the next run of the Large Hadron Collider (LHC). Assuming the Duhram model, we estimate the associated cross sections for the rapidity ranges probed by central and forward detectors. A comparison with the predictions for the exclusive ALP production by photon -- induced interactions is presented. Our results indicate that the contribution of gluon -- induced interactions is nonnegligible and can become domin…
We report results from five analyses based on data taken with the BABAR detector at the PEP-II asymmetric e+e- collider. Included are branching fraction measurements for many B-meson decays involving eta, eta', omega, phi or a0 mesons and the final state Kspi+pi-, and a full angular analysis of the decay B->phiK*0.
The installation of a new sub-detector has improved the ability of LHCb to measure central exclusive production in Run 2 at the LHC. A measurement of central exclusive $J/ψ$ production is presented and improvements for the analysis of hadronic final states are discussed.
I report BESIII preliminary results on: 1 Measurement of sigma(e+e- ->DDbar at Ecm = 3.773 GeV 2 Study of the DDbar production line shape near Ecm = 3.773 GeV 3 The first observation of singly Cabibbo-suppressed decay, D -> omega pi 4 Measurement of BF(Ds+ -> eta' X) and BF(Ds+ -> eta' rho+) .
We perform a measurement of the CP asymmetry in b->sgamma decays using a sample of 383 BB events collected by the BABAR detector at the PEP-II asymmetric B factory. We reconstruct sixteen flavor-specific B decay modes containing a high-energy photon and a hadronic system (Xs) containing an s quark. We measure the \CP asymmetry to be -0.011+/- 0.030(stat)+/-0.014(syst) for a photon energy threshold at 1.6 GeV and the hadronic system mass between 0.6 and 2.8 GeV/c2.
We present results from BABAR experiment for the measurement of inclusive and exclusive branching fractions of B mesons into final states containing $J/ψ$, $ψ(2S)$ and $χ_c$. The contributions of CP even and odd amplitudes in the decay $B^0 \to J/ψK^{*0}$ are determined from an angular analysis. We report the measurements of the branching ratios $B^0 \to D^{*+}D^{*-}$ and $D^{*+}D^{*-}K^0_S$, and the study of exclusive two-body and quasi-two-body charmless decays. The branching fraction of the decay $B^0 \to K^{*0} γ$ has been determined and the corresponding CP asymmetry has been measured.
The production cross sections of the B+, B0, and B0s mesons, and of their charge conjugates, are measured via exclusive hadronic decays in pPb collisions at the center-of-mass energy sqrt(s_NN) = 5.02 TeV with the CMS detector at the CERN LHC. The data set used for this analysis corresponds to an integrated luminosity of 34.6 inverse nanobarns. The production cross sections are measured in the transverse momentum range between 10 and 60 GeV/c. No significant modification is observed compared to proton-proton perturbative QCD calculations scaled by the number of incoherent nucleon-nucleon colli…
The exclusive $Υ$ photoproduction in proton-proton and proton - nucleus collisions at LHC energies is investigated using the color dipole formalism and considering different models for the $Υ$ wave function and forward dipole - target scattering amplitude. Our goal is to update the color dipole predictions and estimate the theoretical uncertainty present in these predictions. We present predictions for the kinematical ranges probed by the ALICE, CMS and LHCb Collaborations.
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 K0B e+ nu_e, pi0 e+ nu_e, K0B* e+ nu_e, and rho0 e+ nu_e, and the first observation and absolute branching fraction measurement of D+ --> omega e+ nu_e. We also report the most precise tests to date of isospin invariance in semileptonic D0 and D+ decays.
A search for the exclusive radiative decays B --> rho(770) gamma and B0 --> omega(782) gamma is performed on a sample of about 84\times 10^{6} B\bar B events collected by the BaBar detector at the PEP-II asymmetric-energy e+e- storage ring. No significant signal is seen in any of the channels. We set upper limits on the branching fractions of BR(B^0 -> rho^0 gamma) < 1.2 \times 10^{-6}, BR(B^+ -> rho^+ gamma) < 2.1 \times 10^{-6}, and BR(B^0 -> omega gamma) < 1.0 \times 10^{-6} at 90% confidence level (C.L.). Using the assumption that Gamma(B --> rho gamma) = Gamma(B+ --> rho+ gamma) =2\timesΓ…
There has been much progress in measurements of charmless hadronic B decays during 1997. Building on the previous indications from CLEO and LEP, CLEO now has clear signals in five exclusive final states: K^+π^, K^0π^+, etapr K^+, etapr K^0, and omega K^+. The branching fractions for the etapr K modes are several times larger than the others. A similar strikingly large signal has been seen in the inclusive decay, B->etapr X_S. All of these signals would appear to be dominated by hadronic penguin processes. (Invited talk presented at the Seventh International Symposium On Heavy Flavor Physics, S…
We review recent experimental results on Bd and Bs mesons decays by the BaBar and Belle experiments. These include measurements of the color-suppressed decays B0bar to D(*)0h0, h0=pi0, eta, etaprime, omega, observation of the baryonic decay B0bar to Lambdac+ Lambdabar K-, measurements of the charmless decays B to eta h, h=K, pi, B to Kpi and observation of CP eigenstates in the Bs decays: B0s to J/psi f0(980), B0s to J/psi f0(1370) and B0s to J/psi eta. The theoretical implications of these results will be considered.
This paper describes preliminary results on the inclusive process b --> s gamma obtained from 20.7 fb^-1 of data recorded with the BaBar detector during 1999-2000. Signal event yields are found from a combination of twelve exclusive decay channels after subtracting continuum and BBbar backgrounds. Cross-feed from incorrectly reconstructed b --> s gamma events is also removed. Branching fractions in bins of hadronic mass are calculated using corrected Monte Carlo signal efficiencies; this is equivalent to measuring the gamma energy spectrum. We measure the first moment of the gamma energy spect…
We search for CP-violating asymmetries (Acp) in the B meson decays to K+- pi-+, K+- pi0, Ks pi+-, K+- eta', and omega pi+-. Using 9.66 million Upsilon(4S) decays collected with the CLEO detector, the statistical precision on Acp is in the range of \pm 0.12 to \pm 0.25 depending on decay mode. While CP-violating asymmetries of up to \pm 0.5 are possible within the Standard Model, the measured asymmetries are consistent with zero in all five decay modes studied.
We report a measurement of the branching fraction of the exclusive charmless semileptonic decay B+ --> omega l+ nu, where l is either an electron or a muon. We use samples of B+ mesons tagged by a reconstructed charmed semileptonic decay of the other B meson in the event. The measurement is based on a dataset of 426.1 fb-1 of e+e- collisions at a center-of-mass energy of 10.58 GeV recorded with the BABAR detector at the PEP-II asymmetric-energy e+e- storage rings. We measure a branching fraction of BF(B+ --> omega l+ nu) = (1.35 +/- 0.21 +/- 0.11) x 10(-4), where the uncertainties are statisti…
Backward-angle meson electroproduction above the resonance region, which was previously ignored, is anticipated to offer unique access to the three quark plus sea component of the nucleon wave function. In this letter, we present the first complete separation of the four electromagnetic structure functions above the resonance region in exclusive omega electroproduction off the proton, e + p -> e' + p + omega, at central Q^2 values of 1.60, 2.45 GeV^2 , at W = 2.21 GeV. The results of our pioneering -u ~ -u min study demonstrate the existence of a unanticipated backward-angle cross section peak…
In this paper we study leading neutron production in photon - hadron interactions which take place in $pp$ and $pA$ collisions at large impact parameters. Using a model that describes the recent leading neutron data at HERA, we consider exclusive vector meson production in association with a leading neutron in $pp/pA$ collisions at RHIC and LHC energies. The total cross sections and rapidity distributions of $ρ$, $ϕ$ and $J/Ψ$ produced together with a leading neutron are computed. Our results indicate that the study of these processes is feasible and that it can be used to improve the understa…
We present recent results on charmless hadronic B decays using data collected by the BaBar detector at the PEP-II asymmetric-energy e+e- collider at the Stanford Linear Accelerator Center. We report measurements of branching fractions and charge asymmetries in several charmless two-body, three-body, and quasi-two-body decay modes. We also report measurements of polarization in charmless B decays to exclusive final states with two vector mesons.
Until present the study of the form factors associated to the vector and axial-vector components of the hadronic weak current has been carried out with a plethora of modelizations of the underlying strong interactions. While of importance to get an understanding of the dynamics involved, the amount and quality of the experimental data start to show some discrepancies with the analysed models. Moreover, and from a theoretical point of view, most of these models are not consistent with quantum chromodynamics (QCD). We propose a QCD-based model-independent procedure to analyse those decays throug…
The exclusive vector meson production cross section is one of the most promising observables to probe the high energy regime of the QCD dynamics. In particular, the squared momentum transfer ($t$) distributions are an important source of information about the spatial distribution of the gluons in the hadron and about fluctuations of the color fields. In this paper we complement previous studies on exclusive vector meson photoproduction in hadronic collisions presenting a comprehensive analysis of the $t$ - spectrum measured in exclusive $ρ$, $ϕ$ and $J/Ψ$ photoproduction in $pp$ and $PbPb$ col…
We report evidence for the decay modes X(3872) --> gamma J/psi and X(3872)--> pi+pi-pi0 J/psip. In the latter, the pi+pi-pi0 invariant mass distribution has a strong peak between 750 MeV and the kinematic limit of 775 MeV, suggesting that the process is dominated by the sub-threshold decay X --> omega J/psi. These results establish the charge-conjugation parity of the X(3872) as C=+1. The results are based on a study of X(3872) mesons produced via exclusive B --> K X(3872) decays in a 256 fb-1 data sample collected at the Upsilon(4S) resonance in the Belle detector at the KEKB collider. The X(…
We study semileptonic B decay to the exclusive charmless states pi, rho/omega, eta and eta' using the 16 fb-1 CLEO Upsilon(4S) data sample. We find B(B^0 -> pi^-l^+nu) = (1.37 +- 0.15_stat +- 0.11_sys) x 10^-4 and B(B^0 -> rho^- l^+ nu) = (2.93 +- 0.37_stat +- 0.37_sys) x 10^-4, and find evidence for B^+ -> eta' l^+ nu, with B(B^+ -> eta' l^+ nu) = (2.66 +- 0.80_stat +- 0.56_sys ) x 10^-4. From our B -> pi l nu rate for q^2 > 16 GeV^2 and lattice QCD we find |V_{ub}| = (3.6 +- 0.4_stat +- 0.2_syst +0.6-0.4_thy) x 10^-3.
We report a preliminary study of the branching fractions and $q^2$ distributions of exclusive charmless semileptonic B decays, using events tagged by fully reconstructing one of the $B$ mesons in a hadronic decay mode. These results are obtained from a data sample that contains 535 $\times 10^6\ B\bar{B}$ pairs, collected near the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric energy $e^+ e^-$ collider.
We consider the exclusive decays $B \to D^{(*)}\,\ell \barν$ and study the effect of non $V-A$ structures on the observables. We extend the standard model hadronic current by additional right-handed vector as well as left- and right-handed scalar and tensor contributions and calculate the decay rates including the perturbative corrections up to order $α_s$. Using the data of the exclusive semileptonic $b \to c $ decays and recent calculations of the form factors at the non-recoil point we discuss the constraints to the wrong helicity admixtures in the hadronic current.
We review recent experimental results on B meson decays. These include measurements of the inclusive production of charmed and non-charmed mesons and baryons, the reconstruction of a large number of exclusive hadronic final states with charmed mesons, the search for exclusive hadronic final states without charmed mesons, and the first observation of the decay B-> K* gamma which is described by an electromagnetic penguin diagram. The theoretical implications of these results will be considered. The figures can be obtained in postscript format EMAIL from kh@ohstpy.mps.ohio-state.edu.
Exclusive vector meson photoproduction associated with a leading baryon ($B = n, Δ^+, Δ^0$) in $pp$ and $pA$ collisions at RHIC and LHC energies is investigated using the color dipole formalism and taking into account nonlinear effects in the QCD dynamics. In particular, we compute the cross sections for $ρ$, $ϕ$ and $J/Ψ$ production together with a $Δ$ and compare the predictions with those obtained for a leading neutron. Our results show that the $V + Δ$ cross section is almost 30 % of the $V + n$ one. Our results also show that a future experimental analysis of these processes is, in princi…
In this letter we update our predictions for exclusive $J/Ψ$ and $Υ$ photoproduction in proton-proton and nucleus - nucleus collisions at the Run 2 LHC energies obtained with the color dipole formalism and considering the impact parameter Color Glass Condensate model (bCGC) for the forward dipole - target scattering amplitude. A comparison with the LHCb data on rapidity distributions and photon - hadron cross sections is presented. Our results demonstrate that the current data can be quite well described by the bCGC model, which takes into account nonlinear effects in the QCD dynamics and repr…
A review of current experimental results on exclusive hadronic decays of bottom mesons to a single or double charmed final state is presented. We concentrate on branching fraction measurements conducted at $e^+e^-$ colliders at the $Υ(4s)$ and at the $Z^0$ resonance. The experimental results reported are then used in tests of theoretical model predictions, the determination of the QCD parameters $a_1$ and $a_2/a_1$ and tests of factorization
