Markus Jüngst
Heavy flavour production and spectroscopy are key components of the HERA physics programme. I will summarise a selection of the recent results obtained by the H1 and ZEUS collaborations. The production of excited charm mesons and J/psi will be discussed as well as measurements of b quark cross-sections in photoproduction. The status of searches for exotic bound states and the D*p resonance will be updated.
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Results of the H1 and ZEUS Collaborations on spectroscopy of light and charmed mesons and on pentaquark searches, obtained using the HERA I data, are summarised.
An overview of the recent results on strangeness production and spectroscopy from the electron-proton collider experiments H1 and ZEUS at HERA is presented. Production of particles with light and strange quarks is discussed and compared with both theoretical predictions and with data from e+e- experiments. Measurements in the charm sector cover studies of the radially and orbitally excited charm states. Finally, the investigation of exotic states in the strangeness sector at HERA is reviewed.
Heavy-flavoured jets have been studied in photoproduction at HERA. This includes the first measurement of dijet angular distributions in D* photoproduction and the ratio of the vector/(vector + pseudoscalar) production rate for charm mesons.
Recent results from H1 and ZEUS on searches for exotic baryons in $ep$ collisions at HERA are reviewed. Evidence for the production of the strange pentaquark $Θ^+$ and of a narrow anti-charmed baryon decaying to $D^{*-} p$ together with negative results of pentaquark searches at HERA are presented.
Inclusive photoproduction cross-sections of the neutral mesons eta, rho^0, f_0(980) and f_2(1270) have been measured by H1 and compared to the photoproduction of pi^+ in ep collisions at HERA. Also, inclusive KsKs production and evidence for a narrow baryonic state decaying to Ksp have been observed by ZEUS at HERA.
Recent measurements of Charm and Beauty production at HERA are described. The charm results are well described by NLO QCD calculations with a somewhat better description in the CCFM than in the DGLAP evolution schemes. However, the Beauty results in both photoproduction and in deep inelastic scattering (DIS) are poorly described by such calculations.
Recent results on charm and beauty photoproduction at HERA are discussed. The perturbative QCD calculations are generally smaller than the measured cross sections, particularly in the forward (proton) direction. The study of charm dijet photoproduction is consistent with a significant contribution of charm excitation processes.
The study of heavy flavor production is a central topic of research at HERA and is an important testing ground for perturbative QCD. A selection of results for charm and beauty production in gamma p, using different experimental techniques and compared to different theoretical predictions, obtained by the H1 and ZEUS collaborations will be presented.
Recent results on spectroscopy with special focus on searches for pentaquarks are presented from the H1 and ZEUS collaborations. Cross sections of observed states and upper limits on the production cross section of unobserved states are extracted in order to enable comparison between experiments. Measurements of the inclusive photoproduction of the neutral mesons eta, rho^0, f_0(980) and f_2(1270) in ep interactions at HERA at an average gamma-p collision energy of 210 GeV are also presented.
An overview over the recent heavy flavour results of the H1 and ZEUS collaborations is presented. Various techniques to tag the heavy quark, which allow to explore different phase space regions, are employed. Predictions of pertubative QCD are compared to the charm and beauty production data. Charm and beauty fractions of the proton structure function $F_2$ are
Selected recent ZEUS and H1 results on open charm and beauty production in high energy ep collisions are reviewed. Measurements of differential D* cross sections, charm meson production ratios and semi-leptonic beauty decays are discussed and compared with QCD predictions.
The import of HERA data on heavy quark production for LHC experiments is discussed. Knowlegde of all aspects of the beauty and charm production process, viz. the parton density functions of colliding hadrons, the hard scatter, and the fragmentation of the quarks into hadrons, can aid LHC experimentation. This short write-up concentrates on possible influences HERA data can have and on the current status (and history) of beauty production from both HERA and Tevatron experiments. In general, next-to-leading order QCD gives a reasonable description of beauty production although some regions of ph…
Recent spectroscopy studies performed in high energy ep collisions by the H1 and ZEUS Collaborations are described. The status of the searches for the strange pentaquark, the Theta+, is presented as well as results on searches for further exotic states such as the Sigma--. The evidence for the observation of a pentaquark state containing the charmed quark, the Theta_c, is discussed and the result is given on searches for glueball candidates at HERA.
Recent results from the experiments ZEUS and H1 on charm production in $ep$ collisions are reviewed. The topics are elastic and inelastic $J/ψ$ photoproduction, $D^*$ photoproduction differential cross sections and a first look at the proton structure function F_2^{c\bar{c}}.
Measurements of heavy quark production, particularly from HERA, their theoretical understanding and their relevance for the LHC are reviewed. The status of beauty and charm production is discussed in the context of the different components of the production process: the parton density function of the colliding hadrons; the hard scatter; and the fragmentation of the quarks into hadrons. The theory of QCD at next-to-leading order generally describes well the hadronic structure and the production of heavy quarks although sometimes fails in details which are highlighted. The fragmentation of heavy…
Recent results on heavy flavor production at HERA are presented. New measurements of charm production are available in the region of $ Q^2 <$ 1000 GeV$^2$ for $D^*$ and in the photoproduction limit, $Q^2\to 0$, for $D_s$. The results are compared to theoretical calculations and the charm proton structure function \f2cc$(x,Q^2)$ is extracted. A new independent measurement of the $b\bar{b}$ cross section using a $b$-lifetime tag is reported.
New results with increased statistics are presented for heavy flavour production at Q2<150 Gev2 and in the photoproduction limit Q2-->0. Cross sections for Dstar production, F2charm, the gluon density in the proton, and inelastic J/psi production are discussed and compared to theoretical calculations. A first measurement of the b anti-b cross section is reported.
Heavy flavour production is one of the key components of the HERA II physics programme. While most of the results presented use leptons or the reconstruction of charmed mesons to identify heavy flavour production, both the H1 and ZEUS experiments now have working microvertex detectors that are being used more and more. In this talk I will summarise a selection of the recent results obtained by the two collaborations.
Recent results on jet cross sections and heavy-flavor production in photoproduction and neutral current deep inelastic ep scattering from the H1 and ZEUS Collaborations are presented. The jet measurements are used to perform stringent tests of perturbative QCD, to extract precise values of the strong coupling and to constrain further the proton and photon parton distribution functions. The measurement of beauty and charm production at HERA is an important testing ground for perturbative QCD and can provide information on the structure of the proton.
Studies of charm and beauty production in ep collisions with a center-of-mass energy of 318 GeV are reported from the two HERA collaborations, H1 and ZEUS. The analyses make use of both the HERA-I data sample recorded between 1996 and 2000 and a sample from HERA-II, which started in 2003. The cross sections measured by both H1 and ZEUS experiments are compared with next-to-leading order QCD calculations. The measurement of the charm and beauty contributions to the proton structure function is also presented. The comparison to next-to-next-to-leading order (NNLO) calculations shows agreement wi…
Recent results on inclusive D^0 and D^{*+-} production in deeply inelastic ep scattering at sqrt(s)=301 GeV are summarized. The data have been collected by the H1 and ZEUS experiments at HERA. The total and the differential cross sections are discussed in the framework of LO and NLO QCD predictions. The data exhibit clear evidence for boson gluon fusion dominating open heavy flavor production in the kinematic range currently explored at HERA. The measurements of F_2^{cc}(x,Q^2) at small Bjorken x are presented. The prospects for future analyses of open charm and beauty production including det…
Differential cross sections, $dσ/d x_γ^{\rm OBS}$, for dijet photoproduction events with a tagged $D^*$ meson are presented, where $x_γ^{\rm OBS}$ is the fraction of the photon energy contributing to the two highest transverse energy jets. Results on open beauty cross sections (from semileptonic decays) compared to LO Monte Carlo predictions are also presented.
The production of heavy quarks has been studied in photoproduction processes with the ZEUS detector at HERA using an integrated luminosity of $36.9 pb^{-1}$. Events with a photon virtuality, $Q^2<1 GeV^2$, were selected with two jets of high transverse energy and an electron in the final state. Consideration of the distribution in $p_T^{rel}$ - the momentum of the electron transverse to the axis of the jet to which the electron is closest - allows a measurement of the beauty cross-section in a restricted region of phase space.
The production of charm and beauty quarks in ep collisions at HERA has been studied by the H1 and ZEUS collaborations. Charm production is generally well described in total rate and in shape by next to leading order (NLO) calculations in perturbative quantum chromodynamics (QCD), although in specific phase space corners the NLO calculations underestimate the observed cross sections. More and more beauty production data are becoming available. For this process, NLO QCD predictions tend to be lower than the measurements.
Production of final states containing open charm and beauty quarks at HERA is reviewed. Photoproduction (PHP) of the charm meson resonances D^*, D^0 and D_s, as well as D^* production in the deep inelastic scattering (DIS) regime, are measured and compared to QCD predictions. The excited charm mesons D^0_1(2420), D^{*0}_2(2460) and D^{+-}_{s1}(2536) have been observed and the rates of charm quarks hadronising to these mesons were extracted. A search for radially excited charm mesons has been performed. PHP and DIS beauty cross sections are higher than expected in next-to-leading order QCD.
Recent results on spectroscopy and the measurement of hadronic final states in ep collisions from the H1 and ZEUS collaborations are presented using data sets with an integrated luminosity between 44 and 121 pb^-1 collected during the HERA I running period. Besides a search for resonant states which could be interpreted as pentaquarks, a study of charged particle momentum spectra in the Breit frame and a measurement of neutral strange hadron production is shown. Furthermore two recent measurements of prompt photons are presented and compared with pQCD calculations. The measurements are perform…
Light and charmed hadrons are produced copiously in ep collisions with a centre-of-mass energy of 318 GeV at HERA. Results of the ZEUS Collaboration on pentaquark searches, deuteron and antideuteron production and charmed-meson spectroscopy, obtained using the HERA I data, are summarised.
We review the theoretical and experimental status of heavy-flavour production at HERA. The results presented include some outstanding issues in charm and beauty photoproduction, charm production in DIS and quarkonium production.
The cross section for anti-deuteron photoproduction is measured at HERA at a mean centre-of-mass energy of W_{γp} = 200 GeV in the range 0.2 < p_T/M < 0.7 and |y| < 0.4, where M, p_T and y are the mass, transverse momentum and rapidity in the laboratory frame of the anti-deuteron, respectively. The numbers of anti-deuterons per event are found to be similar in photoproduction to those in central proton-proton collisions at the CERN ISR but much lower than those in central Au-Au collisions at RHIC. The coalescence parameter B_2, which characterizes the likelihood of anti-deuteron production, is…
Heavy excited electrons and neutrinos have been sought by the H1 and ZEUS experiments at HERA. For the e* (nu*) searches, 120 pb^-1 (16 pb^-1) of ep collision data have been analysed. No evidence for any excited lepton has been found, and limits on the characteristic couplings have been derived.
A selection of topics on open heavy quark production at HERA are reviewed here. Measurements of charm fragmentation parameters will be presented together with developments in the study of D* di-jet angular distributions. Charm production in deep inelastic scattering (DIS) is also discussed. Finally we deal with recent measurements of b cross sections using impact parameters in both DIS and photoproduction regimes.
New QCD results obtained by the H1 Collaboration are summarized. These results are based on data taken in $e^{\pm}p$ collisions at HERA I (1994-2002) and HERA II (2003-2007) corresponding to an integrated luminosity of almost $\rm 0.5 fb^{-1}$. The data were taken at an electron {Electron means electron and positron.} beam energy of $E_{e}=27.5$ GeV and proton beam energies of $\rm E_{p}=820 GeV, 920 GeV, 575 GeV$ and $\rm 460 GeV$. A direct measurement of $F_{L}$, jet production and measurement of $α_{s}$, production of heavy quarks and diffractive photo-production of jets are presented.
The experimental talks presented in the working group D ``Heavy Flavours'' of the DIS04 workshop are summarised. New and recently updated results from Tevatron, HERA, LEP, B-factories and neutrino experiments are discussed.
The final results on the combination of all inclusive deep-inelastic scattering cross section data from the H1 and ZEUS experiments at HERA are reviewed. The parton distribution functions (PDFs) extracted from these data (HERAPDF2.0) and from HERA data on heavy flavour production and jet production are also presented (HERAPDF2.0Jets). The use of various heavy flavour schemes is compared and the sensitivity of the data to cuts on Q2 is explored. When jet data are included in the fits, a competitive value of $α_s(M_Z)=0.1184 \pm 0.0016$ is extracted at NLO, excluding scale uncertainties
We review recent results from the H1 and ZEUS experiments at HERA on charm and beauty production in ep collisions at 300 - 318 GeV centre-of-mass energy.
Heavy quark structure functions from HERA provide a direct handle on the medium and small-x gluon PDF. In this contribution, we discuss ongoing progress on the implementation of the FONLL General-Mass scheme with running heavy quark masses, and of its benchmarking with the HOPPET and OpenQCDrad codes, and then present the impact of the recently released combined HERA charm production cross sections in the NNPDF2.3 analysis. We find that the combined charm data contribute to constraining the gluon and quarks at small values of Bjorken-x.
The HERA-B experiment at DESY has acquired a data set of approximately 300,000 decays J/psi -> l+l- during its 2002/2003 data-taking period. These data are used to analyze the production of heavy quarks in proton-nucleus interactions at a center-of-mass energy of 41.6 GeV. In this article, preliminary results of two measurements are discussed, a measurement of nuclear effects in the production of J/psi mesons and a measurement of the b-bbar production cross section.
Measurements of the suppression of the yield per nucleon and differential distributions of $J / ψ$ production for 920 GeV/c protons incident on heavy nuclear targets have been made with broad coverage in $p_T$ and negative coverage in $x_F$ of produced meson. Production ratios of $ψ(2S)$ to $J / ψ$ and $χ_c$ to $J / ψ$ have been measured with a high accuracy. The $D^+$ and $D^0$ production cross sections as well as $D^+$ to $D^0$ ratio have been obtained on one of the highest statistics available in proton nucleus experiments.
Using the ZEUS detector at HERA, we have searched for heavy excited states of electrons, neutrinos, and quarks in $e^+p$ collisions at a center-of-mass energy of 300~GeV. With an integrated luminosity of 9.4~pb$^{-1}$, no evidence was found for electroweak production and decay of such states. Limits on the production cross section times branching ratio and on the characteristic couplings, $f/Λ$, are derived for masses up to 250~GeV. For the particular choice $f/Λ= 1/M_{f^*}$, we exclude at the 95% confidence level excited electrons with mass between 30 and 200~GeV, excited electron neutrinos w…
A selection of recent results on heavy quark production at the HERA collider by the H1 and ZEUS collaborations are presented with a focus on charmonium production in DIS, charm fragmentation and beauty production.
Differential photoproduction cross sections are measured for events containing D* mesons. The data were taken with the H1 detector at the ep collider HERA and correspond to an integrated luminosity of 51.1 pb-1. The kinematic region covers small photon virtualities Q^2 < 0.01 GeV^2 and photon-proton centre-of-mass energies of 171 < W_gammap < 256 GeV. The details of the heavy quark production process are further investigated in events with one or two jets in addition to the D* meson. Differential cross sections for D* jet production are determined and the correlations between the D* meson and …
With the discovery of new states in recent years, interest in spectroscopy has revived. Recent experimental results in heavy flavour spectroscopy are reviewed, including charmonium, bottomonium, charmed mesons and baryons and bottom mesons.
Recent results from H1 and ZEUS on heavy flavour production at HERA are reviewed
The reaction e+p --> e+X is studied with the H1 detector at Hera. The data cover momentum transfers Q^2 between 200 GeV^2 and 30,000 GeV^2 and correspond to an integrated luminosity of 35.6 pb^(-1). The differential cross section dsigma/dQ^2 is compared to the Standard Model expectation for neutral current scattering and analysed to search for bar(e)e bar(q)q contact interactions. No evidence for new phenomena is observed. The results are used to set limits on scales within models of electron--quark compositeness, quark form factors and the exchange of virtual heavy leptoquarks. A search for g…
This paper reviews the experimental status of the Heavy Quarkonium Spectroscopy and highlights the measurements that hint at the existence of a new form of quark and gluon aggregation beyond the mesons and the baryons.
New results on charm and beauty electroproduction from the H1 and ZEUS Collaborations at the ep collider HERA are presented. Differential cross sections are compared to a next-to-leading order QCD calculation. The heavy quark contributions, F_2^{cc} and F_2^{bb}, to the proton structure function F_2 are compared using different experimental techniques. Also, results are shown on the charm fragmentation function, thereby testing the universality of fragmentation.
Recent experimental results on heavy quarkonia spectroscopy and decays are reviewed. In particular, new results are discussed on charmonium spin singlet states, bottomonium D-states, photon and hadronic transitions from heavy quarkonium states, and the unexplained narrow X(3872) state.
The pp collision data collected in the LHC Run I provides a great opportunity for heavy flavour studies. The latest results on exotic states, heavy baryon and $B_c^+$ mesons are reviewed.
The Tevatron experiments have each accumulated about 6 \ifb good data since the start of RUN II. This large dataset provided good opportunities for heavy flavor spectroscopy studies at the Tevatron. This article will cover the recent omega_b obervation, new $Υ(nS)$ polarization studies as well as exotic meson spectroscopy studies.
Most recent measurements of open charm and beauty production in high energy ep collisions at HERA are reviewed. The measurements explored the different aspects of quantum chromodynamics involved in the process of heavy flavor production. The results are compared with perturbative theoretical calculations at next-to-leading order.
Measurements of open charm production cross sections in deep-inelastic ep scattering at HERA from the H1 and ZEUS Collaborations are combined. Reduced cross sections sigma_red^{c\bar{c}} for charm production are obtained in the kinematic range of photon virtuality 2.5<Q2<2000 GeV2 and Bjorken scaling variable 0.00003<x<0.05. The combination method accounts for the correlations of the systematic uncertainties among the different data sets. The combined charm data together with the combined inclusive deep-inelastic scattering cross sections from HERA are used as input for a detailed NLO QCD anal…
A search for physics beyond the Standard Model has been performed with high-Q^2 neutral current deep inelastic scattering events recorded with the ZEUS detector at HERA. Two data sets, e^+ p \to e^+ X and e^- p \to e^- X, with respective integrated luminosities of 112 pb^-1 and 16 pb^-1, were analyzed. The data reach Q^2 values as high as 40000 GeV^2. No significant deviations from Standard Model predictions were observed. Limits were derived on the effective mass scale in eeqq contact interactions, the ratio of leptoquark mass to the Yukawa coupling for heavy leptoquark models and the mass sc…
We summarize the main measurements performed with the LHCb detector on production and spectroscopy in the heavy flavour sector, using data samples recorded during 2010 and 2011 data taking in proton-proton collisions at $\sqrt s=7$\,TeV .
Latest results on the heavy flavour production and spectroscopy at the LHC are reviewed. These include measurements of production rates of the charmed and beauty hadrons, and observations of new excited charmed and beauty hadrons and exotic states.
Searches in ep collisions for heavy excited fermions have been performed with the ZEUS detector at HERA. Excited states of electrons and quarks have been searched for in e^+p collisions at a centre-of-mass energy of 300 GeV using an integrated luminosity of 47.7 pb^-1. Excited electrons have been sought via the decays e*->egamma, e*->eZ and e*->nuW. Excited quarks have been sought via the decays q*->qgamma and q*->qW. A search for excited neutrinos decaying via nu*->nugamma, nu*->nuZ and nu*->eW is presented using e^-p collisions at 318 GeV centre-of-mass energy, corresponding to an integrated…
An overview of recent measurements of charm and beauty production in ep collisions at HERA is presented. Various techniques are used by the ZEUS and H1 collaborations to efficiently tag heavy quarks in events and different regions of phase space are explored. Differential cross sections are measured in both photoproduction and deep-inelastic scattering. The predictions based on perturbative QCD calculations at next-to-leading order are generally found to describe the proton structure and the production of heavy quarks.
The production of charm and beauty quarks in $γγ$ collisions at LEP, $ep$ collisions at HERA and $p \bar{p}$ collisions at the Tevatron is discussed. The comparison with predictions of next-to-leading-order QCD and the issues it raises are detailed. In particular, the strengths and weaknesses of the measurements and predictions are discussed.
Current issues in the studies of Heavy Flavours in colliders are described with particular emphasis on experiments in which the UK is involved. Results on charm production at HERA are examined and compared to those at the Tevatron. B production rates at the Tevatron as well as the status of B lifetimes and mixing in the LEP collaborations and at the Tevatron are highlighted. The measurement of sin2beta from CDF is described as well as the most recent results on top physics at the Tevatron.
Recent results on the properties of the hadronic final state at the HERA collider are presented. Strangeness production and correlations have been studied in the laboratory system for deep inelastic scattering (DIS). Inclusive $K^0_S$, $Λ$ and $\barΛ$ production has been measured and compared to Monte Carlo model calculations. No significant $Λ$ to $\barΛ$ production asymmetry was observed and the measured $Λ(\barΛ)$ polarisations are consistent with zero. Bose-Einstein correlations between charged and neutral kaons have been studied and the obtained results are compared with the LEP measureme…
Data from H1 and ZEUS on the structure and the quark and gluon densities of the proton are discussed. A brief excursion is made into the field of inclusive diffraction by deep inelastic scattering. The comparison of e- p and e+ p scattering at large momentum transfers demonstrates clearly the presence of weak contributions in neutral current interactions. The comparison with the corresponding charged current results shows at Q2 values above the masses squared of the heavy vector bosons the unification of electromagnetic and weak interactions. The new data are testing the validity of the Standa…
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