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Author |
Noguera, S.; Vento, V. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
The pion transition form factor and the pion distribution amplitude |
Type |
Journal Article |
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Year |
2010 |
Publication |
European Physical Journal A |
Abbreviated Journal |
Eur. Phys. J. A |
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Volume |
46 |
Issue |
2 |
Pages |
197-205 |
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Keywords ![sorted by Keywords field, descending order (down)](img/sort_desc.gif) |
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Abstract |
Recent BaBar data on the pion transition form factor, whose Q(2)-dependence is much steeper then predicted by asymptotic Quantum Chromodynamics (QCD), have caused a renewed interest in its theoretical description. We present here a formalism based on a model-independent description for low photon virtuality and a high photon virtuality description based on QCD, which match at a scale Q(0). The high photon virtuality description incorporates a flat pion distribution amplitude, phi(x) = 1, at the matching scale Q(0) and QCD evolution from Q(0) to Q > Q(0). The flat pion distribution is connected, through soft pion theorems and chiral symmetry, to the pion valence parton distribution at the same low scale Q(0). The procedure leads to a good description of the data, and by incorporating additional twist-three effects, to an excellent description of the data. |
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Address |
[Noguera, S.] Univ Valencia, Dept Fis Teor, CSIC, E-46100 Valencia, Spain, Email: Santiago.Noguera@uv.es |
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Springer |
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English |
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ISSN |
1434-6001 |
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Notes |
ISI:000284869600005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ elepoucu @ |
Serial |
312 |
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Author |
Kaskulov, M.; Hernandez, E.; Oset, E. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
On the background in the gamma p -> omega(pi(0)gamma)p reaction and mixed event simulation |
Type |
Journal Article |
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Year |
2010 |
Publication |
European Physical Journal A |
Abbreviated Journal |
Eur. Phys. J. A |
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Volume |
46 |
Issue |
2 |
Pages |
223-230 |
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Keywords ![sorted by Keywords field, descending order (down)](img/sort_desc.gif) |
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Abstract |
In this paper we evaluate sources of background of the gamma p -> omega p reaction, with the omega detected through its pi(0)gamma decay channel, to compare with the experiment carried out at ELSA. We find background from gamma p -> pi(0)pi(0)p followed by decay of a pi(0) into two gamma, recombining one pi(0) and one gamma, and from the gamma p -> pi(0)eta p reaction with subsequent decay of the eta into two photons. This background accounts for the data at pi(0)gamma invariant masses beyond 700 MeV, but strength is missing at lower invariant masses which was attributed to photon misidentification events, which we simulate to get a good reproduction of the experimental background. Once this is done, we perform an event mixing simulation to reproduce the calculated background and we find that the method provides a good description of the background. A closer look reveals this is accidental. We show that the mixed event generated background in the region of the omega mass and beyond is completely tied to the events at low pi(0)gamma invariant masses where the d sigma/dM(pi 0 gamma) distribution is much larger. This has as a consequence that the mixed event method produces the same background at high invariant masses independently of the actual background in that region, as a consequence of which, the method is unsuited to give the background at energies around the peak of the omega and beyond. |
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Address |
[Kaskulov, M.] Univ Giessen, Inst Theoret Phys, D-35392 Giessen, Germany, Email: murat.kaskulov@theo.physik.uni-giessen.de |
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Publisher |
Springer |
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English |
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1434-6001 |
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Notes |
ISI:000284869600008 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
313 |
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Author |
Doring, M.; Oset, E.; Meissner, U.G. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Evaluation of the polarization observables I-S and I-C in the reaction gamma p -> pi(0)eta p |
Type |
Journal Article |
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Year |
2010 |
Publication |
European Physical Journal A |
Abbreviated Journal |
Eur. Phys. J. A |
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Volume |
46 |
Issue |
2 |
Pages |
315-323 |
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Keywords ![sorted by Keywords field, descending order (down)](img/sort_desc.gif) |
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Abstract |
We evaluate the polarization observables I-S and I-C for the reaction gamma p -> pi(0)eta p, using a chiral unitary framework developed earlier. The I-S and I-C observables have been recently measured for the first time by the CBELSA/TAPS Collaboration. The theoretical predictions of I-S and I-C, given for altogether 18 angle-dependent functions, are in good agreement with the measurements. Also, the asymmetry d Sigma/dcos theta evaluated here agrees with the data. We show the importance of the Delta(1700) D-33-resonance and its S-wave decay into eta Delta(1232). The result can be considered as a further confirmation of the dynamical nature of this resonance. At the highest energies, deviations of the predictions from the data start to become noticeable, which leaves room for additional processes and resonances such as a Delta(1940) D-33. We also point out how to further improve the calculation. |
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Address |
[Doering, M.; Meissner, U. -G.] Forschungszentrum Julich, Inst Kernphys, D-52425 Julich, Germany, Email: m.doering@fz-juelich.de |
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Springer |
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English |
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ISSN |
1434-6001 |
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Notes |
ISI:000284869600016 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
314 |
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Permanent link to this record |
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Author |
CDF Collaboration (Aaltonen, T. et al); Cabrera, S. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Search for single top quark production in p(p)over-bar collisions at root s=1.96 TeV in the missing transverse energy plus jets topology |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
81 |
Issue |
7 |
Pages |
072003 - 24pp |
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Keywords ![sorted by Keywords field, descending order (down)](img/sort_desc.gif) |
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Abstract |
We report a search for single top quark production with the CDF II detector using 2: 1 fb(-1) of integrated luminosity of p (p) over bar collisions at root s = 1.96 TeV. The data selected consist of events characterized by large energy imbalance in the transverse plane and hadronic jets, and no identified electrons and muons, so the sample is enriched in W -> tau nu decays. In order to suppress backgrounds, additional kinematic and topological requirements are imposed through a neural network, and at least one of the jets must be identified as a b quark jet. We measure an excess of signal-like events in agreement with the standard model prediction, but inconsistent with a model without single top quark production by 2.1 standard deviations (sigma), with a median expected sensitivity of 1.4 sigma. Assuming a top quark mass of 175 GeV/c(2) and ascribing the excess to single top quark production, the cross section is measured to be 4.9(-2.2)(+2.5) (stat + syst) pb, consistent with measurements performed in independent data sets and with the standard model prediction. |
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Address |
[Aaltonen, T.; Mehtala, P.; Orava, R.; Osterberg, K.; Saarikko, H.; van Remortel, N.] Univ Helsinki, Div High Energy Phys, Dept Phys, FIN-00014 Helsinki, Finland |
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Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
Place of Publication |
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English |
Summary Language |
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Original Title |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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ISSN |
1550-7998 |
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Notes |
ISI:000277201900007 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
287 |
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Permanent link to this record |
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Author |
BABAR Collaboration (del Amo Sanchez, P. et al); Lopez-March, N.; Martinez-Vidal, F.; Milanes, D.A.; Oyanguren, A. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Observation of the Y(1(3)D(J)) bottomonium state through decays to pi(+)pi Y-(1S) |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
82 |
Issue |
11 |
Pages |
111102 - 7pp |
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Keywords ![sorted by Keywords field, descending order (down)](img/sort_desc.gif) |
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Abstract |
Based on 122 X 10(6)Y(3S) events collected with the BABAR detector, we have observed the Y(1(3)D(J)) bottomonium state through the Y(3S) -> gamma gamma Y(1(3)D(J)) -> gamma gamma pi(+)pi Y-(1S) decay chain. The significance for the J = 2 member of the Y(1(3)D(J)) triplet is 5.8 standard deviations including systematic uncertainties. The mass of the J = 2 state is determined to be 10 164.5 +/- 0.8(stat) +/- 0.5(syst) MeV/c(2). We use the pi(+)pi(-) invariant mass distribution to confirm the consistency of the observed state with the orbital angular momentum assignment of the Y(1(3)D(J)). |
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Address |
[Sanchez, P. del Amo; Lees, J. P.; Poireau, V.; Prencipe, E.; Tisserand, V.] Univ Savoie, LAPP, CNRS, IN2P3, F-74941 Annecy Le Vieux, France |
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Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1550-7998 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
ISI:000286577200001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
528 |
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Permanent link to this record |