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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Molecular aspects of charm physics

We study the influence of possible molecular structures in the charmonium spectrum. We focus on the 0{sup ++}, 1{sup ++} and 1{sup --} sectors. In the first one we coupled the 2{sup 3}P{sub 0}cc pair with DD, J/{psi}{omega}, D{sub s}D{sub s} and J/{psi}{phi} channels and we obtain two states compatibles with the X(3945) and the Y(3940). In the second one we couple the 2{sup 3}P{sub 1}cc state with the DD{sup *} channel and we obtain a dressed state compatible with the X(3940) and a new state that we assign to the X(3872). In the third one we include the 3{sup 3}S{sub 1} and 2{sup 3}D{sub 1} charmonium states coupled to DD, DD{sup *}, D{sup *}D{sup *}, D{sub s}D{sub s}, D{sub s}D{sup *}s and D{sup *}{sub s}D{sup *}{sub s}. In this calculation we obtain a new molecular state that could be the G(3900) or the controversial Y(4008) and two cc states dressed by the molecular components assigned to the {psi}(4040) and the {psi}(4160). Finally we perform a calculation in the five quark sector where we can describe the {Lambda}{sub c}(2940){sup +} as a ND{sup *} molecular state and predict a {Lambda}{sub b}(6248){sup +} state.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Interpreting the peak structures around 1800 MeV in the BES data on J/Ψ→φπ{sup +}π{sup −}, J/Ψ→γωφ

In this talk we present an interpretation for the experimental data available on two different processes, namely, J/Ψ→φπ{sup +}π{sup −}, J/Ψ→γωφ, which seem to indicate existence of two new resonances with the same quantum numbers (J{sup πc} = 0{sup ++}, I = 0) and savery similar mass (1800 MeV) but with very different decay properties. However, our studies show that the peak structure found in the ωφ invariant mass, in J/Ψ→γωφ, is a manifestation of the well known f{sub 0}(1710) while the cross section enhancement found in J/Ψ→φπ{sup +}π{sup −} is indeed a new f{sub 0} resonance with mass near 1800 MeV. We present an explanation for the different decay properties of these two scalar resonances.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Recent Results of {psi}{sup '} decays at BESIII

BES-III at BEPC-II has collected about 106M {psi}{sup '} and 226M J/{psi} events. With these events, many exciting results have been obtained. In this talk, we report the recent results of {psi}{sup '} decays from the BESIII, e.g. h{sub c} production in {psi}{sup '} and {psi}{sup '} radiative decays to the pseudoscalar meson (P = {pi}{sup 0}/{eta}/{eta}{sup '}).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Charm production in a strong magnetic field

We discuss the effects of a strong magnetic field on B and D mesons, focusing on the changes of the energy levels and the masses of the bound states. Using the Color Evaporation Model we discuss the possible changes in the production of J/ψ and Υ. We briefly comment the recent experimental data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Exclusive vector meson production at HERA

The exclusive photoproduction of {Upsilon} has been studied with the ZEUS detector in ep collisions at HERA. The exponential slope, b, of the |t|-dependence of the cross section, where t is the squared four-momentum transfer at the proton vertex, has been measured. This constitutes the first measurement of the |t|-dependence of the {gamma}p{yields}{Upsilon}p cross section. The differential crosssections as a function of t at lower energies of {gamma}p centre-of-mass has been studied in exclusive diffractive photoproduction of J/{psi} mesons with the H1 detector. The exclusive electroproduction of two pions has been measured by the ZEUS experiment. The two-pion invariant-mass distribution is interpreted in terms of the pion electromagnetic form factor, assuming that the studied mass range includes the contributions of the {rho}, {rho} Prime and . {rho}'' vector-meson states.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Measurement of the product of the leptonic width of the J/ψ meson and the branching ratio for its decay to hadrons

A preliminary result of the KEDR/VEPP-4M experiment devoted to measuring the cross section for electron-positron annihilation to hadrons (e{sup +}e{sup −} → hadrons) in the energy region of J/ψ-resonance production is presented. The value found for the product of the J/ψ-meson width with respect to decay to electrons and the branching ratio for J/ψ-meson decay to hadrons is Γ{sub ee}B{sub h} = 4.67±0.04(stat.)± 0.22(syst.) keV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Momentum Dependence of Near-Threshold J/ψ Photoproduction off Nuclei

The photoproduction of J/ψ mesons off nuclei at the energies of 8 and 11 GeV, which are close to the threshold for their production on a free nucleon, is considered on the basis of the first-collisionmodel relying on the nuclear spectral function and including incoherent processes of charmonium production in photon–nucleon collisions. The model takes into account the absorption of final J/ψ mesons, the binding of target nucleons, and their Fermi motion, as well as the effect of the scalar J/ψ–nucleus potential (or the inmedium shift of the J/ψ-meson mass) on these processes. Under various assumptions on the magnitude of this shift, the momentum dependences of various observables, such as the relative transparency of carbon and gold nuclei and the J/ψ-meson yields, are calculated for meson production on these nuclei. The observables in question include the relative transparencies of these nuclei to J/ψ mesons and the absolute and relativemeson yields from them. It is shown that, at the energy of 11 GeV, which is above the threshold, the first observable is virtually independent of the in-medium change in the J/ψ-meson mass. At the same time, it is moderately sensitive to this change at the subthreshold energy of 8 GeV. On the other hand, it is shown that, at these photon energies, the absolute and relative values of the differential cross sections, especially for the the heavy nucleus of {sup 197} Au, in the momentum range of 4–6 GeV/с are highly sensitive to the in-medium change in the J/ψ-meson mass. Therefore, the present calculations can be used to determine the unknown shift of the J/ψ-meson mass in nuclei by means of comparing their results with data expected from experiments in Hall C at the Continuous Electron Beam Accelerator Facility (CEBAF, USA) upgraded to the energy of 12 GeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Exclusive photoproduction of J/ψ and ψ(2S) in pp and AA collisions

The amplitude for γp → J/ψp(γp → ψ'p) is calculated in a pQCD k{sub ⊥}-factorization approach. The total cross section for this process is calculated for different unintegrated gluon distributions and compared with the HERA data and the data extracted recently by the LHCb collaboration. The amplitude for γp → J/ψp(γp → ψ'p) is used to predict the cross section for exclusive photoproduction of the J/ψ(ψ') meson in proton-proton and nucleus-nucleus collisions. In the pp case, compared to earlier calculations we include both Dirac and Pauli electromagnetic form factors. We also discuss the dependence of nuclear shadowing on the charmonium state.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Ultra-peripheral heavy-ion collisions with CMS

Ultra-peripheral collisions (UPCs) of heavy ions involve long range electromagnetic interactions at impact parameters larger than twice the nuclear radius. At TeV energies, the strong electromagnetic field due to the coherent action of the Z = 82 proton charges generates a large flux of photons, which can be used for high-energy photoproduction studies. Heavy vector mesons produced in electromagnetic interactions provide direct information on the parton distribution functions in the nucleus at very low values of Bjorken-x. These events are characterized by a very low hadron multiplicity. The wide pseudo-rapidity coverage of the CMS detectors is used to separate such events from very peripheral nuclear interactions. The CMS experiment has excellent capabilities for the measurement of the heavy vector mesons in the dimuon decay channel using the tracker and the muon chambers. This analysis demonstrates CMS’s capabilities for measuring J/ψ and the two-photon process in ultra-peripheral collisions, using the 2011 PbPb and 2013 pPb data. The prospects for future measurements using the data to be collected in the 2015 PbPb run will be described.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Multiple charm production at the LHC energy

Cross sections for J/{psi} mesons produced in association with open charm and two charmed hadrons from different cc-bar pairs under LHC conditions are predicted theoretically. The respective processes are considered both in single and in double parton interactions. Particular attention is given to kinematical limits of the LHCb detector, and a comparison with the most recent experimental data is performed for them.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2015

Photoproduction of vector mesons in ultra-peripheral p–Pb and Pb–Pb collisions at the LHC with the ALICE experiment

Vector mesons are copiously produced in ultra-peripheral collisions. In these collisions, the impact parameter is larger than the sum of the radii of the two projectiles, implying that electromagnetic processes become dominant. The cross section of production of vector mesons is expected to be sensitive to the gluon distribution and can therefore probe nuclear gluon shadowing (Pb–Pb) and the gluon structure function in the nucleon (p-Pb). The ALICE Collaboration has performed the first measurements of the production of ρ{sup 0}, J/ψ and ψ/(2S) in Pb–Pb ultra-peripheral collision as well as the cross section for exclusive J/ψ photoproduction off protons in ultra-peripheral proton-lead collisions at the LHC. The results are compared to the STARLIGHT Monte Carlo and to QCD based models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Formation of a 4c tetraquark in J/{psi}-meson pair production at LHC

Cross sections for J{psi}-meson pair production in proton-proton interaction at the c.m. collision energy of {radical}a = 7 TeV were theoretically predicted under conditions of various kinematical cuts. The possible contribution to this process from the decays of 4c tetraquarks, new hypothetic particles consisting of two valence c quarks and two valence c-bar antiquarks, was studied. It is shown that at least one such state (tensor 4c tetraquark) can in principle be observed experimentally under conditions of the LNCb experiment.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Cold matter effects and quarkonium production at RHIC and LHC

In this work we investigate two cold matter effects in J/{Psi} and {Upsilon} production in nuclear collisions at RHIC and LHC, namely the shadowing effect and nuclear absorption. We characterize these effects by estimating the rapidity dependence of some nuclear ratios in pA and AA collisions at RHIC and LHC, R{sub pA} = d{sigma}{sub pA}(J/{Psi},{Upsilon})/Ad{sigma}{sub pp}(J/{Psi},{Upsilon}) and R{sub AA} = d{sigma}{sub AA}(J/{Psi},{Upsilon})/A{sup 2}d{sigma}{sub pp}(J/{Psi},{Upsilon}).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

J/{psi} measurements in 7 TeV p-p collisions with ALICE using EMCal-triggered events

J/{psi} measurements can be performed with the ALICE experiment through the dilepton decay into e{sup -}e{sup +} (for rapidity Double-Vertical-Line y Double-Vertical-Line <0.9) and {mu}{sup -}{mu}{sup +} (for rapidity -4.0<y<-2.5) pairs, in protonproton, proton-nucleus and nucleus-nucleus collisions. Proton-proton collisions are specially important for the ALICE physics program, since they provide baseline results to be compared with Pb-Pb, where one expects the production of the Quark Gluon Plasma (QGP). Moreover, these measurements are interesting per se because the mechanism of charmonium production in hadron interactions is not yet fully understood. The ALICE Eletromagnetic Calorimeter (EMCal) p{sub T} extends the range of J/{psi} measurements, since it provides electron/hadron discrimination for higher p{sub T} values in comparison to other electron PID techniques in ALICE. The EMCal can also provide fast triggers for events containing high energy electrons. In 2011, during proton-proton collisions at 7 TeV, the ALICE EMCal trigger was intensively used for event selection of showers above 4.8 GeV. In this work, some results from 2011 proton-proton collisions are presented, showing a J/{psi} measurement for transversal momentum above 6 GeV/c, due to a combination of the ALICE EMCal PID and trigger system.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Quarkonium +{gamma} production in coherent interactions at LHC

The quarkonium plus photon production in coherent hadron - hadron interactions at LHC is studied using the non-relativistic QCD (NRQCD) factorization formalism. Considering different sets of NRQCD matrix elements we estimate the rapidity distribution and total cross section for H+{gamma} (H=J/{Psi} and {gamma}) production. Our results demonstrate that the experimental analysis of this process is feasible and that it can be used to constrain the matrix elements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

On effects of multiple gluons in J/ψ hadroproduction

The three-gluon contribution to J/ψ hadroproduction is calculated within perturbative QCD in the k{sub T}-factorization framework. This mechanism involves double gluon density and enters at a non-leading twist, but it is enhanced at large energies due to large double gluon density at small x. We obtain results for differential p{sub T}-dependent cross-sections for all J/ψ polarisations. The rescattering contribution is found to provide a significant correction to the standard leading twist cross-section at the energies of the Tevatron or the LHC at moderate p{sub T}. We also discuss a possible contribution of the rescattering correction to the anti-shadowing effect for J/ψ production in proton - nucleus collisions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Estimates of Z boson and J/ψ production cross sections at the large hadron collider

We calculate the leading-order cross section for the associated production of Z and J/ψ. Processes that include associated production of electroweak bosons and heavy quarkonium can give valuable insight into the production mechanism of quarkonia. We conclude that this process is accessible by the LHC statistics.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Exotic quarkonium states in CMS

The studies of the production of the X(3872), either prompt or from B-hadron decays, and of the J/ψϕ mass spectrum in B-hadron decays have been carried out by using pp collisions at √s = 7 TeV collected with the CMS detector at the LHC. The cross-section ratio of the X(3872) with respect to the ψ(2S) in the J/ψπ{sup +}π{sup −} decay channel and the fraction of X(3872) coming from B-hadron decays are measured as a function of transverse momentum (p{sub T}), covering unprecedentedly high values of p{sub T}. For the first time, the prompt X(3872) cross section times branching fraction is extracted differentially in p{sub T} and compared with NRQCD predictions. The dipion invariant-mass spectrum of the J/ψπ{sup +}π{sup −} system in the X(3872) decay is also investigated. A peaking structure in the J/ψϕ mass spectrum near threshold is observed in B{sup ±} → J/ψϕK{sup ±} decays. The data sample, selected on the basis of the dimuon decay mode of the J/ψ, corresponds to an integrated luminosity of 5.2 fb{sup −1}. Fitting the structure to an S-wave relativistic Breit–Wigner lineshape above a three-body phase-space nonresonant component gives a signal statistical significance exceeding five standard deviations. The fitted mass and width values are m = 4148.0 ± 2.4(stat.) ± 6.3(syst.) MeV and Γ = 28+15 − 11(stat.) ± 19(syst.) MeV, respectively. Evidence for an additional peaking structure at higher J/ψϕ mass is also reported.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗