P Ambrozewicz

Publications (175)199.87 Total impact

• Article: An initial study of mesons and baryons containing strange quarks with GlueX

  The GlueX Collaboration, A. AlekSejevs, S. Barkanova, M. Dugger, B. Ritchie, I. Senderovich, E. Anassontzis, P. Ioannou, C. Kourkoumeli, G. Voulgaris, [......], M. McCaughan, M. Pennington, L. Pentchev, Y. Qiang, E. S. Smith, A. Somov, S. Taylor, T. Whitlatch, E. Wolin, B. Zihlmann
  [show abstract] [hide abstract]
  ABSTRACT: The primary motivation of the GlueX experiment is to search for and ultimately study the pattern of gluonic excitations in the meson spectrum produced in $\gamma p$ collisions. Recent lattice QCD calculations predict a rich spectrum of hybrid mesons that have both exotic and non-exotic $J^{PC}$, corresponding to $q\bar{q}$ states ($q=u,$ $d,$ or $s$) coupled with a gluonic field. A thorough study of the hybrid spectrum, including the identification of the isovector triplet, with charges 0 and $\pm1$, and both isoscalar members, $|s\bar{s}\ >$ and $|u\bar{u}\ > + |d\bar{d}\ >$, for each predicted hybrid combination of $J^{PC}$, may only be achieved by conducting a systematic amplitude analysis of many different hadronic final states. Detailed studies of the performance of the \gx detector have indicated that identification of particular final states with kaons is possible using the baseline detector configuration. The efficiency of kaon detection coupled with the relatively lower production cross section for particles containing hidden strangeness will require a high intensity run in order for analyses of such states to be feasible. We propose to collect a total of 200 days of physics analysis data at an average intensity of $5\times 10^7$ tagged photons on target per second. This data sample will provide an order of magnitude statistical improvement over the initial GlueX running, which will allow us to begin a program of studying mesons and baryons containing strange quarks. In addition, the increased intensity will permit us to study reactions that may have been statistically limited in the initial phases of GlueX. Overall, this will lead to a significant increase in the potential for \gx to make key experimental advances in our knowledge of hybrid mesons and excited $\Xi$ baryons.
  05/2013;
• Article: A study of meson and baryon decays to strange final states with GlueX in Hall D (A proposal to the 39th Jefferson Lab Program Advisory Committee)

  The GlueX Collaboration, M. Dugger, B. Ritchie, E. Anassontzis, P. Ioannou, C. Kourkoumeli, G. Voulgaris, N. Jarvis, W. Levine, P. Mattione, [......], M. Ito, D. Lawrence, L. Pentchev, Y. Qiang, E. S. Smith, A. Somov, S. Taylor, T. Whitlatch, E. Wolin, B. Zihlmann
  [show abstract] [hide abstract]
  ABSTRACT: The primary motivation of the GlueX experiment is to search for and ultimately study the pattern of gluonic excitations in the meson spectrum produced in gamma p collisions. Recent lattice QCD calculations predict a rich spectrum of hybrid mesons that have both exotic and non-exotic JPC, corresponding to q q-bar (q=u, d, or s) states coupled with a gluonic field. A thorough study of the hybrid spectrum, including the identification of the isovector triplet, with charges 0 and +-1, and both isoscalar members, |s s-bar> and |u u-bar> + |d d-bar>, for each predicted hybrid combination of JPC, may only be achieved by conducting a systematic amplitude analysis of many different hadronic final states. We propose the development of a kaon identification system, supplementing the existing GlueX forward time-of-flight detector, in order to cleanly select meson and baryon decay channels that include kaons. Once this detector has been installed and commissioned, we plan to collect a total of 200 days of physics analysis data at an average intensity of 5 x 10^7 tagged photons on target per second. This data sample will provide an order of magnitude statistical improvement over the initial GlueX data set and, with the developed kaon identification system, a significant increase in the potential for GlueX to make key experimental advances in our knowledge of hybrid mesons and Cascade baryons.
  10/2012;
• Source

  Available from: W. J. Briscoe

  Article: Evidence for a backward peak in the γd → π0d cross section near the η threshold

  The CLAS Collaboration, Y. Ilieva, B. L. Berman, A. E. Kudryavtsev, I. I. Strakovsky, V. E. Tarasov, M. Amarian, P. Ambrozewicz, M. Anghinolfi, G. Asryan, [......], L. B. Weinstein, D. P. Weygand, M. Williams, E. Wolin, M. H. Wood, A. Yegneswaran, L. Zana, J. Zhang, B. Zhao, Z. Zhao
  [show abstract] [hide abstract]
  ABSTRACT: High-quality cross sections for the reaction γd → π0 d have been measured using the CLAS at Jefferson Lab over a wide energy range near and above the η-meson photoproduction threshold. At backward c.m. angles for the outgoing pions, we observe a resonance-like structure near E γ = 700 MeV. Our model analysis shows that it can be explained by η excitation in the intermediate state. The effect is the result of the contribution of the N(1535)S 11-resonance to the amplitudes of the subprocesses occurring between the two nucleons and of a two-step process in which the excitation of an intermediate η-meson dominates.
  European Physical Journal A 04/2012; 43(3):261-267. · 2.19 Impact Factor
• Source

  Available from: John Robert Arrington

  Article: Probing the high momentum component of the deuteron at high Q2.

  W U Boeglin, L Coman, P Ambrozewicz, K Aniol, J Arrington, G Batigne, P Bosted, A Camsonne, G Chang, J P Chen, [......], M Roedelbronn, A Saha, K Slifer, P Solvignon, V Sulkosky, P E Ulmer, E Voutier, L B Weinstein, B Wojtsekhowski, M Zeier
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  ABSTRACT: The (2)H(e,e'p)n cross section at a momentum transfer of 3.5 (GeV/c)(2) was measured over a kinematical range that made it possible to study this reaction for a set of fixed missing momenta as a function of the neutron recoil angle θ(nq) and to extract missing momentum distributions for fixed values of θ(nq) up to 0.55  GeV/c. In the region of 35°≤θ(nq)≤45° recent calculations, which predict that final-state interactions are small, agree reasonably well with the experimental data. Therefore, these experimental reduced cross sections provide direct access to the high momentum component of the deuteron momentum distribution in exclusive deuteron electrodisintegration.
  Physical Review Letters 12/2011; 107(26):262501. · 7.37 Impact Factor
• Source

  Available from: Eugene Pasyuk

  Article: New Measurement of the π0 radiative decay width.

  I Larin, D McNulty, E Clinton, P Ambrozewicz, D Lawrence, I Nakagawa, Y Prok, A Teymurazyan, A Ahmidouch, A Asratyan, [......], A Shahinyan, A Sitnikov, D Sober, S Stepanyan, W Stephens, J Underwood, A Vasiliev, V Vishnyakov, M Wood, S Zhou
  [show abstract] [hide abstract]
  ABSTRACT: High precision measurements of the differential cross sections for π0 photoproduction at forward angles for two nuclei, 12C and 208Pb, have been performed for incident photon energies of 4.9-5.5 GeV to extract the π0→γγ decay width. The experiment was done at Jefferson Lab using the Hall B photon tagger and a high-resolution multichannel calorimeter. The π0→γγ decay width was extracted by fitting the measured cross sections using recently updated theoretical models for the process. The resulting value for the decay width is Γ(π0→γγ)=7.82±0.14(stat)±0.17(syst)  eV. With the 2.8% total uncertainty, this result is a factor of 2.5 more precise than the current Particle Data Group average of this fundamental quantity, and it is consistent with current theoretical predictions.
  Physical Review Letters 04/2011; 106(16):162303. · 7.37 Impact Factor
• Source

  Available from: S. R. Gevorkyan

  Article: A New Measurement of the $\pi^0$ Radiative Decay Width

  I. Larin, D. McNulty, E Clinton, P Ambrozewicz, D Lawrence, I Nakagawa, Y Prok, A Teymurazyan, A. Ahmidouch, A. Asratyan, [......], A. Shahinyan, A. Sitnikov, D. Sober, S Stepanyan, W. Stephens, J. Underwood, A. Vasiliev, V. Vishnyakov, M Wood, S Zhou
  [show abstract] [hide abstract]
  ABSTRACT: High precision measurements of the differential cross sections for $\pi^0$ photoproduction at forward angles for two nuclei, $^{12}$C and $^{208}$Pb, have been performed for incident photon energies of 4.9 - 5.5 GeV to extract the ${\pi^0 \to \gamma\gamma}$ decay width. The experiment was done at Jefferson Lab using the Hall B photon tagger and a high-resolution multichannel calorimeter. The ${\pi^0 \to \gamma\gamma}$ decay width was extracted by fitting the measured cross sections using recently updated theoretical models for the process. The resulting value for the decay width is $\Gamma{(\pi^0 \to \gamma\gamma)} = 7.82 \pm 0.14 ~({\rm stat.}) \pm 0.17 ~({\rm syst.}) ~{\rm eV}$. With the 2.8% total uncertainty, this result is a factor of 2.5 more precise than the current PDG average of this fundamental quantity and it is consistent with current theoretical predictions.
  09/2010;
• Article: High-resolution spectroscopy of Lambda16N by electroproduction.

  F Cusanno, G M Urciuoli, A Acha, P Ambrozewicz, K A Aniol, P Baturin, P Y Bertin, H Benaoum, K I Blomqvist, W U Boeglin, [......], R Subedi, V A Sulkosky, T Suzuki, H Ueno, P E Ulmer, P Veneroni, E Voutier, B B Wojtsekhowski, X Zheng, C Zorn
  [show abstract] [hide abstract]
  ABSTRACT: An experimental study of the (16)O(e,e'K(+))(Lambda)(16)N reaction has been performed at Jefferson Lab. A thin film of falling water was used as a target. This permitted a simultaneous measurement of the p(e,e'K(+))Lambda, Sigma(0) exclusive reactions and a precise calibration of the energy scale. A ground-state binding energy of 13.76+/-0.16 MeV was obtained for (Lambda)(16)N with better precision than previous measurements on the mirror hypernucleus (Lambda)(16)O. Precise energies have been determined for peaks arising from a Lambda in s and p orbits coupled to the p(1/2) and p(3/2) hole states of the (15)N core nucleus.
  Physical Review Letters 11/2009; 103(20):202501. · 7.37 Impact Factor
• Article: Photodisintegration of 4He into p+t

  R. Nasseripour, B. L. Berman, N. Benmouna, Y. Ilieva, J. M. Laget, K. P. Adhikari, M. J. Amaryan, P. Ambrozewicz, M. Anghinolfi, H. Baghdasaryan, [......], M. F. Vineyard, D. P. Watts, L. B. Weinstein, D. P. Weygand, M. Williams, E. Wolin, M. H. Wood, J. Zhang, B. Zhao, Z. W. Zhao
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  ABSTRACT: The two-body photodisintegration of 4He into a proton and a triton has been studied using the CEBAF Large-Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. Real photons produced with the Hall-B bremsstrahlung-tagging system in the energy range from 0.35 to 1.55 GeV were incident on a liquid 4He target. This is the first measurement of the photodisintegration of 4He above 0.4 GeV. The differential cross sections for the γ4He→pt reaction were measured as a function of photon-beam energy and proton-scattering angle and are compared with the latest model calculations by J.-M. Laget. At 0.6-1.2 GeV, our data are in good agreement only with the calculations that include three-body mechanisms, thus confirming their importance. These results reinforce the conclusion of our previous study of the three-body breakup of 3He that demonstrated the great importance of three-body mechanisms in the energy region 0.5-0.8 GeV.
  Phys. Rev. C. 10/2009; 80(4).
• Article: Measurement of direct f0(980) photoproduction on the proton.

  M Battaglieri, R De Vita, A P Szczepaniak, K P Adhikari, M Aghasyan, M J Amaryan, P Ambrozewicz, M Anghinolfi, G Asryan, H Avakian, [......], D P Weygand, M Williams, E Wolin, M H Wood, A Yegneswaran, M Yurov, L Zana, J Zhang, B Zhao, Z W Zhao
  [show abstract] [hide abstract]
  ABSTRACT: We report on the results of the first measurement of exclusive f_{0}(980) meson photoproduction on protons for E_{gamma}=3.0-3.8 GeV and -t=0.4-1.0 GeV2. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. The resonance was detected via its decay in the pi;{+}pi;{-} channel by performing a partial wave analysis of the reaction gammap-->ppi;{+}pi;{-}. Clear evidence of the f_{0}(980) meson was found in the interference between P and S waves at M_{pi;{+}pi;{-}} approximately 1 GeV. The S-wave differential cross section integrated in the mass range of the f_{0}(980) was found to be a factor of about 50 smaller than the cross section for the rho meson. This is the first time the f_{0}(980) meson has been measured in a photoproduction experiment.
  Physical Review Letters 04/2009; 102(10):102001. · 7.37 Impact Factor
• Article: Electroproduction of pπ+π- off protons at 0.2<Q2<0.6 GeV2 and 1.3<W<1.57 GeV with the CLAS detector

  G. V. Fedotov, V. I. Mokeev, V. D. Burkert, L. Elouadrhiri, E. N. Golovatch, B. S. Ishkhanov, E. L. Isupov, N. V. Shvedunov, G. Adams, M. J. Amaryan, [......], M. F. Vineyard, A. V. Vlassov, L. B. Weinstein, D. P. Weygand, M. Williams, E. Wolin, M. H. Wood, A. Yegneswaran, L. Zana, J. Zhang
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  ABSTRACT: This paper reports on the most comprehensive data set obtained on differential and fully integrated cross sections for the process ep→e'pπ+π-. The data were collected with the CLAS detector at Jefferson Laboratory. Measurements were carried out in the as yet unexplored kinematic region of photon virtuality 0.2<Q2<0.6 GeV2 and invariant mass of the final hadron system W from 1.3 to 1.57 GeV. For the first time, nine independent one-fold differential cross sections were determined in each bin of W and Q2 covered by the measurements. A phenomenological analysis of the data allowed us to establish the most significant mechanisms contributing to the reaction. The nonresonant mechanisms account for a major part of cross sections. However, we find sensitivity to s-channel excitations of low-mass nucleon resonances, especially to the N(1440)P11 and N(1520)D13 states in kinematic dependencies of the one-fold differential cross sections.
  Phys. Rev. C. 01/2009; 79(1).
• Article: Electroproduction of pπ+π- off protons at 0.2<Q2<0.6 GeV2 and 1.3<W<1.57 GeV with the CLAS detector

  G. V. Fedotov, V. I. Mokeev, V. D. Burkert, L. Elouadrhiri, E. N. Golovatch, B. S. Ishkhanov, E. L. Isupov, N. V. Shvedunov, G. Adams, M. J. Amaryan, [......], M. F. Vineyard, A. V. Vlassov, L. B. Weinstein, D. P. Weygand, M. Williams, E. Wolin, M. H. Wood, A. Yegneswaran, L. Zana, J. Zhang
  [show abstract] [hide abstract]
  ABSTRACT: This paper reports on the most comprehensive data set obtained on differential and fully integrated cross sections for the process ep→e'pπ+π-. The data were collected with the CLAS detector at Jefferson Laboratory. Measurements were carried out in the as yet unexplored kinematic region of photon virtuality 0.2<Q2<0.6 GeV2 and invariant mass of the final hadron system W from 1.3 to 1.57 GeV. For the first time, nine independent one-fold differential cross sections were determined in each bin of W and Q2 covered by the measurements. A phenomenological analysis of the data allowed us to establish the most significant mechanisms contributing to the reaction. The nonresonant mechanisms account for a major part of cross sections. However, we find sensitivity to s-channel excitations of low-mass nucleon resonances, especially to the N(1440)P11 and N(1520)D13 states in kinematic dependencies of the one-fold differential cross sections.
  Phys. Rev. C. 01/2009; 79(1).
• Source

  Available from: L. Lagamba

  Article: High Resolution Spectroscopy of 16N_Lambda by Electroproduction

  F. Cusanno, G. M. Urciuoli, A. Acha, P Ambrozewicz, K. A. Aniol, P. Baturin, P Y Bertin, H Benaoum, K. I. Blomqvist, W. U. Boeglin, [......], R. Subedi, V. A. Sulkosky, T Suzuki, H Ueno, P E Ulmer, P Veneroni, E. Voutier, B. B. Wojtsekhowski, X. Zeng, C. Zorn
  [show abstract] [hide abstract]
  ABSTRACT: An experimental study of the 16O(e,e'K^+)16N_Lambda reaction has been performed at Jefferson Lab. A thin film of falling water was used as a target. This permitted a simultaneous measurement of the p(e,e'K^+)Lambda,Sigma_0 exclusive reactions and a precise calibration of the energy scale. A ground-state binding energy of 13.76 +/- 0.16 MeV was obtained for 16N_Lambda with better precision than previous measurements on the mirror hypernucleus 16O_Lambda. Precise energies have been determined for peaks arising from a Lambda in s and p orbits coupled to the p_{1/2} and p_{3/2} hole states of the 15N core nucleus. Comment: 5 pages, 3 figures, 2 tables
  10/2008;
• Article: Polarized structure function σLT' for 1H(e⃗,e'K+)Λ in the nucleon resonance region

  R. Nasseripour, B. A. Raue, D. S. Carman, P. Ambrozewicz, M. J. Amaryan, E. Anciant, M. Anghinolfi, B. Asavapibhop, G. Asryan, G. Audit, [......], D. P. Weygand, M. Williams, E. Wolin, M. H. Wood, A. Yegneswaran, J. Yun, L. Zana, J. Zhang, B. Zhao, Z. W. Zhao
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  ABSTRACT: The first measurements of the polarized structure function σLT' for the reaction 1H(e⃗,e'K+)Λ in the nucleon resonance region are reported. Measurements are included from threshold up to W=2.05 GeV for central values of Q2 of 0.65 and 1.00 GeV2, and nearly the entire kaon center-of-mass angular range. σLT' is the imaginary part of the longitudinal-transverse response and is expected to be sensitive to interferences between competing intermediate s-channel resonances, as well as resonant and nonresonant processes. The results for σLT' are comparable in magnitude to previously reported results from CLAS for σLT, the real part of the same response. An intriguing sign change in σLT' is observed in the high Q2 data at W≈1.9 GeV. Comparisons to several existing model predictions are shown.
  Phys. Rev. C. 06/2008; 77(6).
• Article: Measurement of deeply virtual compton scattering beam-spin asymmetries.

  F X Girod, R A Niyazov, H Avakian, J Ball, I Bedlinskiy, V D Burkert, R De Masi, L Elouadrhiri, M Garçon, M Guidal, [......], D P Watts, L B Weinstein, D P Weygand, M Williams, E Wolin, M H Wood, A Yegneswaran, L Zana, J Zhang, Z W Zhao
  [show abstract] [hide abstract]
  ABSTRACT: The beam-spin asymmetries in the hard exclusive electroproduction of photons on the proton (e p-->epgamma) were measured over a wide kinematic range and with high statistical accuracy. These asymmetries result from the interference of the Bethe-Heitler process and of deeply virtual Compton scattering. Over the whole kinematic range (x(B) from 0.11 to 0.58, Q2 from 1 to 4.8 GeV2, -t from 0.09 to 1.8 GeV2), the azimuthal dependence of the asymmetries is compatible with expectations from leading-twist dominance, A approximately a sinphi/(1+c cosphi). This extensive set of data can thus be used to constrain significantly the generalized parton distributions of the nucleon in the valence quark sector.
  Physical Review Letters 04/2008; 100(16):162002. · 7.37 Impact Factor
• Source

  Available from: W. J. Briscoe

  Article: Bayesian analysis of pentaquark signals from CLAS data.

  D G Ireland, B McKinnon, D Protopopescu, P Ambrozewicz, M Anghinolfi, G Asryan, H Avakian, H Bagdasaryan, N Baillie, J P Ball, [......], L B Weinstein, D P Weygand, M Williams, E Wolin, M H Wood, A Yegneswaran, L Zana, J Zhang, B Zhao, Z W Zhao
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  ABSTRACT: We examine the results of two measurements by the CLAS collaboration, one of which claimed evidence for a Theta(+) pentaquark, while the other found no such evidence. The unique feature of these two experiments was that they were performed with the same experimental setup. Using a Bayesian analysis, we find that the results of the two experiments are in fact compatible with each other, but that the first measurement did not contain sufficient information to determine unambiguously the existence of a Theta(+). Further, we suggest a means by which the existence of a new candidate particle can be tested in a rigorous manner.
  Physical Review Letters 03/2008; 100(5):052001. · 7.37 Impact Factor
• Article: Cross sections and beam asymmetries for e⃗p→enπ+ in the nucleon resonance region for 1.7⩽Q2⩽4.5 GeV2

  K. Park, V. D. Burkert, W. Kim, I. G. Aznauryan, R. Minehart, L. C. Smith, K. Joo, L. Elouadrhiri, G. Adams, M. J. Amaryan, [......], E. Wolin, M. H. Wood, A. Yegneswaran, J. Yun, M. Yurov, L. Zana, B. Zhang, J. Zhang, B. Zhao, Z. W. Zhao
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  ABSTRACT: The exclusive electroproduction process e⃗p→e'nπ+ was measured in the range of the photon virtuality Q2=1.7-4.5 GeV2, and the invariant mass range for the nπ+ system of W=1.15-1.7 GeV using the CEBAF Large Acceptance Spectrometer. For the first time, these kinematics are probed in exclusive π+ production from protons with nearly full coverage in the azimuthal and polar angles of the nπ+ center-of-mass system. The nπ+ channel has particular sensitivity to the isospin ½ excited nucleon states, and together with the pπ0 final state will serve to determine the transition form factors of a large number of resonances. The largest discrepancy between these results and present modes was seen in the σLT' structure function. In this experiment, 31,295 cross section and 4,184 asymmetry data points were measured. Because of the large volume of data, only a reduced set of structure functions and Legendre polynomial moments can be presented that are obtained in model-independent fits to the differential cross sections.
  Phys. Rev. C. 01/2008; 77(1).
• Source

  Available from: W. J. Briscoe

  Article: Search for medium modifications of the rho meson.

  R Nasseripour, M H Wood, C Djalali, D P Weygand, C Tur, U Mosel, P Muehlich, G Adams, M J Amaryan, P Ambrozewicz, [......], D P Watts, L B Weinstein, M Williams, E Wolin, A Yegneswaran, L Zana, B Zhang, J Zhang, B Zhao, Z W Zhao
  [show abstract] [hide abstract]
  ABSTRACT: The photoproduction of vector mesons on various nuclei has been studied using the CLAS detector at Jefferson Laboratory. The vector mesons, rho, omega, and varphi, are observed via their decay to e;{+}e;{-}, in order to reduce the effects of final-state interactions in the nucleus. Of particular interest are possible in-medium effects on the properties of the rho meson. The rho mass spectrum is extracted from the data on various nuclei, 2H, C, Fe, and Ti. We observe no significant mass shift and some broadening consistent with expected collisional broadening for the rho meson.
  Physical Review Letters 01/2008; 99(26):262302. · 7.37 Impact Factor
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  Available from: Paul Baturin

  Article: High resolution spectroscopy of (lambda)(12)B by electroproduction.

  M Iodice, F Cusanno, A Acha, P Ambrozewicz, K A Aniol, P Baturin, P Y Bertin, H Benaoum, K I Blomqvist, W U Boeglin, [......], H Ueno, P E Ulmer, G M Urciuoli, P Veneroni, E Voutier, B B Wojtsekhowski, Y Ye, X Zheng, S Zhou, C Zorn
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  ABSTRACT: An experiment measuring electroproduction of hypernuclei has been performed in hall A at Jefferson Lab on a 12C target. In order to increase counting rates and provide unambiguous kaon identification two superconducting septum magnets and a ring imaging Cherenkov detector were added to the hall A standard equipment. An unprecedented energy resolution of less than 700 keV FWHM has been achieved. Thus, the observed (Lambda)(12)B spectrum shows for the first time identifiable strength in the core-excited region between the ground-state s-wave Lambda peak and the 11 MeV p-wave Lambda peak.
  Physical Review Letters 09/2007; 99(5):052501. · 7.37 Impact Factor
• Article: Erratum: Cross sections for the γp→K*0Σ+ reaction at Eγ=1.7-3.0 GeV [Phys. Rev. C 75, 042201 (2007)]

  I. Hleiqawi, K. Hicks, D. S. Carman, T. Mibe, G. Niculescu, A. Tkabladze, M. Amarian, P. Ambrozewicz, M. Anghinolfi, G. Asryan, [......], D. P. Weygand, S. Whisnant, M. Williams, E. Wolin, M. H. Wood, A. Yegneswaran, L. Zana, J. Zhang, B. Zhao, Z. Zhao
  Physical Review C 08/2007; 76(3):39905. · 3.31 Impact Factor
• Article: Q2 dependence of the S11(1535) photocoupling and evidence for a P-wave resonance in η electroproduction

  H. Denizli, J. Mueller, S. Dytman, M. L. Leber, R. D. Levine, J. Miles, K. Y. Kim, G. Adams, M. J. Amaryan, P. Ambrozewicz, [......], D. P. Weygand, M. Williams, E. Wolin, M. H. Wood, A. Yegneswaran, J. Yun, L. Zana, J. Zhang, B. Zhao, Z. W. Zhao
  [show abstract] [hide abstract]
  ABSTRACT: New cross sections for the reaction ep→e'ηp are reported for total center-of-mass energy W=1.5-2.3 GeV and invariant squared momentum transfer Q2=0.13-3.3 GeV2. This large kinematic range allows the extraction of new information about response functions, photocouplings, and ηN coupling strengths of baryon resonances. A sharp structure is seen at W~1.7 GeV. The shape of the differential cross section is indicative of the presence of a P-wave resonance that persists to high Q2. Improved values are derived for the photocoupling amplitude for the S11(1535) resonance. The new data greatly expand the Q2 range covered, and an interpretation of all data with a consistent parametrization is provided.
  Phys. Rev. C. 07/2007; 76(1).