Upsilon Resonances Research Articles

The strong decay of higher vector Upsilon(11020) state in the framework of non-relativistic quark model

An analytical study of a source of Beauty mesons (B mesons) by the Strong decay of Upsilon(11020) is performed to obtain various modes of B mesons. The non-relativistic quark model framework is used to predict the masses of the bottomonium mesons. The strong decay of the Upsilon(11020) state is calculated utilizing Quark Pair Creation model. In addition, the branching ratio of the strong decay has been calculated for each decay width and using them to estimate the number of B-meson pairs for each strong decay width. The results show reasonable agreement with recent Particle Data Group data, in particular with the total strong decay width of Upsilon(11020). The Upsilon(11020) particle is expected to be a good candidate for the conventional Upsilon(6S) state and provides both types of strange and non-strange B mesons. We found new conclusions for the strong decay widths of the Upsilon(11020) in the relativistic phase space. The strong width of the B^{*}B^{*} channel is predicted to be the highest width by the ratio (cong 51%) concerning higher vector Upsilon(11020) State. In addition, the specific B_{s}B_{s}^{*} channel is expected to be the highest width relative to higher Upsilon resonances.

Canonical interpretation of Y(10750) and Upsilon (10860) in the Upsilon family

Inspired by the new resonance Y(10750), we calculate the masses and two-body OZI-allowed strong decays of the higher vector bottomonium sates within both screened and linear potential models. We discuss the possibilities of Upsilon (10860) and Y(10750) as mixed states via the S-D mixing. Our results suggest that Y(10750) and Upsilon (10860) might be explained as mixed states between 5S- and 4D-wave vector b{bar{b}} states. The Y(10750) and Upsilon (10860) resonances may correspond to the mixed states dominated by the 4D- and 5S-wave components, respectively. The mass and the strong decay behaviors of the Upsilon (11020) resonance are consistent with the assignment of the Upsilon (6S) state in the potential models.

Tetraquark Interpretation of the BELLE Data on the AnomalousΥ(1S)π+π−andΥ(2S)π+π−Production near theΥ(5S)Resonance

We analyze the Belle data [K. F. Chen (Belle Collaboration), Phys. Rev. Lett. 100, 112001 (2008); I. Adachi (Belle Collaboration), arXiv:0808.2445] on the processes e+ e- --> Upsilon(1S)pi+ pi-, Upsilon(2S)pi+ pi- near the peak of the Upsilon(5S) resonance, which are found to be anomalously large in rates compared to similar dipion transitions between the lower Upsilon resonances. Assuming these final states arise from the production and decays of the J(PC)=1(--) state Y(b)(10,890), which we interpret as a bound (diquark-antidiquark) tetraquark state [bq][bq], a dynamical model for the decays Y(b) --> Upsilon(1S)pi+ pi-, Upsilon(2S)pi+ pi- is presented. Depending on the phase space, these decays receive significant contributions from the scalar 0(++) states, f0(600) and f0(980), and from the 2(++) qq-meson f(2)(1270). Our model provides excellent fits for the decay distributions, supporting Y(b) as a tetraquark state.

Searches for Lepton Flavor Violation in the Decaysτ±→e±γandτ±→μ±γ

Searches for lepton-flavor-violating decay of a tau lepton to a lighter mass lepton and a photon have been performed with the entire dataset of (963 +- 7) x 10^6 tau decays collected by the BaBar detector near the Upsilon(4S), Upsilon(3S) and Upsilon(2S) resonances. The searches yield no evidence of signals and we set upper limits on the branching fractions of BR(tau -> e gamma) < 3.3 x 10^-8 and BR(tau -> mu gamma) < 4.4 x 10^-8 at 90% confidence level.

Search for Dimuon Decays of a Light Scalar Boson in Radiative TransitionsΥ→γA0

We search for evidence of a light scalar boson in the radiative decays of the Upsilon(2S) and Upsilon(3S) resonances: Upsilon(2S,3S)-> gamma A0, A0 -> mu^+ mu^-. Such a particle appears in extensions of the Standard Model, where a light CP-odd Higgs boson naturally couples strongly to b-quarks. We find no evidence for such processes in the mass range 0.212<= m(A0)<= 9.3 GeV in the samples of 99*10^6 Upsilon(2S) and 122*10^6 Upsilon(3S) decays collected by the BABAR detector at the PEP-II B-factory and set stringent upper limits on the effective coupling of the b quark to the A0. We also limit the dimuon branching fraction of the eta_b meson: BR(eta_b->mu^+mu^-)<0.9% at 90% confidence level.

Measurement of thee+e−→bb¯Cross Section betweens=10.54and 11.20 GeV

We report e;{+}e;{-}-->bb[over ] cross section measurements by the BABAR experiment performed during an energy scan in the range of 10.54 to 11.20 GeV at the SLAC PEP-II e;{+}e;{-} collider. A total relative error of about 5% is reached in more than 300 center-of-mass energy steps, separated by about 5 MeV. These measurements can be used to derive precise information on the parameters of the Upsilon(10860) and Upsilon(11020) resonances. In particular we show that their widths may be smaller than previously measured.

Measurement of upper limits forΥ→γ+Rdecays

Motivated by concerns regarding possible two-body contributions to the recently-measured inclusive Upsilon(nS)->gamma+X (n=1, 2, 3) direct photon spectra, we report on a new study of exclusive radiative decays of these narrow Upsilon(nS) resonances into two-body final states R+gamma, with R a narrow resonant hadronic state decaying into four or more charged particles. Such two-body processes are not explicitly addressed in the extant theoretical frameworks used to calculate the inclusive direct photon spectra, and must also be explicitly inserted into Monte Carlo simulations. Using data collected from the CLEO III detector at the Cornell Electron Storage Ring, we present upper limits of order 0.01 per cent for such bottomonium two-body decays as a function of the R recoil mass.

Comparison of particle production in quark and gluon fragmentation ats∼10 GeV

Using data collected with the CLEO III detector at the Cornell Electron Storage Ring, we study the inclusive production of baryons/antibaryons (p, /) and mesons (phi and f_2(1270)) in gluon-fragmentation and quark-fragmentation processes. We first corroborate previous per-event total particle yields in Upsilon(1S)->ggg compared with nearby continuum (e+e- -> qqbar) indicating greater (x2) per-event yields of baryons in 3-gluon fragmentation. We find similar results when we extend that comparison to include the Upsilon(2S) and Upsilon(3S) resonances. With higher statistics, we now also probe the momentum dependence of these per-event particle yields. Next, we compare particle production in the photon-tagged process Upsilon(1S)->gggamma with that in e+e- -> qqbar events, to allow comparison of two-parton with three-parton particle-specific fragmentation. For each particle, we determine the `enhancement' ratio, defined as the ratio of particle yields per gluon fragmentation event compared to quark fragmentation event. Thus defined, an enhancement of 1.0 implies equal per-event production in both gluon and quark fragmentation. In the photon-tagged analysis (U(1S)->gggamma compared to e+e- -> qqbar+gamma), we find almost no enhancement for protons (1.2+/-0.1), but a significant enhancement (1.9+/-0.3) for /\'s. Overall, per-event baryon production in radiative two-gluon fragmentation is somewhat smaller than that observed in three-gluon decays of the Upsilon(1S). Our results for baryon production are inconsistent with the predictions of the JETSET (7.3) fragmentation model.

Dielectron Widths of theΥ(1S,2S,3S)Resonances

We determine the di-electron widths of the Upsilon(1S), Upsilon(2S), and Upsilon(3S) resonances with better than 2% precision by integrating the cross-section of e+e- -> Upsilon over the e+e- center-of-mass energy. Using e+e- energy scans of the Upsilon resonances at the Cornell Electron Storage Ring and measuring Upsilon production with the CLEO detector, we find di-electron widths of 1.354 +- 0.004 (stat) +- 0.020 (syst) keV, 0.619 +- 0.004 +- 0.010 keV, and 0.446 +- 0.004 +- 0.007 keV for the Upsilon(1S), Upsilon(2S), and Upsilon(3S), respectively.

Measurement of the Muonic Branching Fractions of the Narrow Upsilon Resonances

The decay branching fractions of the three narrow Upsilon resonances to mu(+)mu(-) have been measured by analyzing about 4.3 fb(-1) e(+)e(-) data collected with the CLEO III detector. The branching fraction B(Upsilon(1S)-->mu(+)mu(-))=(2.49+/-0.02+/-0.07)% is consistent with the current world average, but B(Upsilon(2S)-->mu(+)mu(-))=(2.03+/-0.03+/-0.08)% and B(Upsilon(3S)-->mu(+)mu(-))=(2.39+/-0.07+/-0.10)% are significantly larger than prior results. These new muonic branching fractions imply a narrower total decay width for the Upsilon(2S) and Upsilon(3S) resonances and lower other branching fractions that rely on these decays in their determination.

Bottom quark mass and QCD duality

The mass of the bottom quark is analyzed in the context of QCD finite energy sum rules. In contrast to the conventional approach, we use a large momentum expansion of the QCD correlator including terms to order αs2(mb2/q2)6 with the upsilon resonances from e+e− annihilation data as main input. A stable result mb(mb)=(4.19±0.05) GeV for the bottom quark mass is obtained. This result agrees with the independent calculations based on the inverse moment analysis.

Extractingαsfrom electron-positron annihilation around 10 GeV

The total cross section for electron-positron annihilation into hadrons is calculated in the region just below the B meson threshold. QCD corrections up to third order, quark mass effects, initial state radiation, the running of alpha_QED and the tails of the Upsilon resonances are included in the prediction. For given alpha_s the prediction is accurate to 0.5 percent. An experimental measurement with the corresponding precision would allow to determine alpha_s with high accuracy at intermediate energies.

Masses, widths, and leptonic widths of the higher upsilon resonances.

The masses, total widths, and leptonic widths of three triplet $s$-wave $b\overline{b}$ states $\ensuremath{\Upsilon}(4S)$, $\ensuremath{\Upsilon}(5S)$, and $\ensuremath{\Upsilon}(6S)$ are determined from measurements of the ${e}^{+}{e}^{\ensuremath{-}}$ annihilation cross section into hadrons for $10.55lWl11.25$ GeV. The resonances are identified from potential model results and their properties are obtained with the help of a simplified coupled-channels calculation. We find $M(4S)=10.577$ GeV, $\ensuremath{\Gamma}(4S)=25$ MeV, ${\ensuremath{\Gamma}}_{\mathrm{ee}}(4S)=0.28$ keV; $M(5S)=10.845$ GeV, $\ensuremath{\Gamma}(5S)=110$ MeV, ${\ensuremath{\Gamma}}_{\mathrm{ee}}(5S)=0.37$ keV; $M(6S)=11.02$ GeV, $\ensuremath{\Gamma}(6S)=90$ MeV, ${\ensuremath{\Gamma}}_{\mathrm{ee}}(6S)=0.16$ keV.

Upsilon Resonances

Upsilon Resonances

Inclusive K0 production in e+ e− annihilation at the upsilon resonances

We report on inclusive K0 production in the region of the upsilon resonances (9.4–10.6 GeV). The K0 yield for the resonances and continuum below the BB threshold is found to be constant at 0.82 ± 0.10 K0 per observed hadronic event. At the ϒ(4S), however, the K0 yield is significantly higher, 1.58 ± 0.35. This increase in K0 production and the differential cross section dσ/dp of kaons are consistent with BB decay of the ϒ(4S) resonance with the bottom quarks subsequently decaying primarily into charmed quarks.

Upper limit for axion production in radiativeϒdecay

We have used the Columbia University--Stony Brook detector at the Cornell Electron Storage Ring to study the decays of UPSILON(1S) and UPSILON(3S) resonances into a single photon plus a long-lived noninteracting particle. We obtain an upper limit on the branching ratio for UPSILON(1S)..--> gamma..+X, where X is undetected. This upper limit is 3.5 x 10/sup -4/ (90% C.L.) for masses m/sub X/ less than 7 GeV. For the UPSILON(3S) the upper limit is 1.2 x 10/sup -4/ (90% C.L.) for masses less than 4 GeV. Also, the product of the branching ratios of UPSILON..--> gamma..+axion and J/psi..--> gamma..+axion is calculated to be 0.6 x 10/sup -9/, inconsistent with theoretical predictions.

Thrust distribution and decays of the ϒ bound states

We have studied the topologies of hadronic events in e +e - annihilation data taken in the region of the upsilon resonances with the non-magnetic CUSB detectors at CESR. Using a thrust-like variable we compare the decay of ϒ, ϒ′ and ϒPrime; find for ϒ″ a significant excess of high thrust events, which we interpret as evidence for electric dipole transitions.

Measurement of Dimuon Production ats12=62GeV

Prompt dimuon production has been measured. Events with mass up to 25 GeV/c/sup 2/ are observed, as well as the J and UPSILON resonances. Cross sections are given for J and UPSILON production. For the continuum, the scaling function F(tau) is measured at very small values of ..sqrt..tau=m/..sqrt..s covering the range 0.05<..sqrt..tau<0.20.

A review of jet behaviour in e+e−annihilation into hadrons

Abstract Experimental data on jet production in e+ e−” annihilation into hadrons is reviewed. The energy range covered is 3 to 17 GeV Ecm, including the charm thres-hold and the Upsilon resonances. Particular attention is paid to methods of jet analysis. Conclusions are drawn from the data by comparing with Monte Carlo generated event samples based on 2 jet, 3 jet and phase space models.

Observation of $\Upsilon$ particles in colliding electron-positron beams

Results of experiments performed at DORIS in 1978 are presented. The mass spectra, decay widths, and angular distribution of UPSILON resonances are presented.