We report the predictions for the 3
q
core contributions to the electroexcitation of the resonances
Δ
(
1232
)
3
2
+
,
N
(
1440
)
1
2
+
,
N
(
1520
)
3
2
-
,
N
(
1535
)
1
2
-
, and
N
(
1675
)
5
2
-
on ...the proton obtained in the light-front relativistic quark model (LF RQM). For these states, experimental data on the electroexcitation transition amplitudes allow us to make comparison between the experiment and LF RQM predictions in wide range of
Q
2
and also to quantify the expected meson-baryon contributions as a function of
Q
2
.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The CLAS detector at Jefferson Lab has provided the dominant part of all available worldwide data on exclusive meson electroproduction off protons in the resonance region. New results on the γυpN* ...transition amplitudes (electrocouplings) are available from analyses of the CLAS data and will be presented. Their impact on understanding of hadron structure will be discussed emphasizing the credible access to the dressed quark mass function that has been achieved for the first time by a combined analysis of the experimental results on the electromagnetic nucleon elastic and N → N* transition form factors. We will also discuss further convincing evidences for a new baryon state N′ (1720)3/2+ found in a combined analysis of charged double pion photo- and electroproduction cross sections off the protons.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Results from the N Program at Jefferson Lab Aznauryan, I G; Burkert, V D; Lee, T -S H ...
Journal of physics. Conference series,
05/2011, Volume:
299, Issue:
1
Journal Article
Peer reviewed
Open access
We discuss the results on the fundamental degrees of freedom underlying the nucleon excitation spectrum and how they evolve as the resonance transitions are investigated with increasingly better ...space-time resolution of the electromagnetic probe. Improved photocouplings for a number of resonant states, those for the N(1720)P13 being significantly changed, have been determined and entered into the 2008 edition of the RPP. Strong sensitivity to the N(1900)P13 state, listed now as a 2-star state in the same edition of RPP, has been observed in KΛ and KΣ photoproduction. None of the earlier observations of a Θ+5(1540) was confirmed in a series of three Jefferson Lab high statistics dedicated measurements, and stringent upper limits on production cross sections were placed in several channels. For the four lowest excited states, the Δ(1232)P33, N(1440)P11, N(1520)D13, and N(1535)S11, the transition amplitudes have been measured in a wide range in photon virtuality Q2. The amplitudes for the Δ(1232) show the importance of the pion-cloud contribution and do not show any sign of approaching the pQCD regime for Q2 < 7 GeV2. For the Roper resonance, N(1440)P11, the data provide strong evidence for this state as a predominantly radial excitation of the nucleon as a 3-quark ground state. For the N(1535)S11, comparison of the results extracted from π and η photo- and electroproduction data allowed one to specify the branching ratios of this state to the πN and ηN channels; they entered into the 2010 edition of the RPP. Measured for the first time, the longitudinal transition amplitude for the N(1535)S11 became a challenge for quark models and can be indicative of large meson-cloud contributions or alternative representations of this state. The N(1520)D13 clearly shows the rapid changeover from helicity-3/2 dominance at the real photon point to helicity-1/2 dominance at Q2 > 0.5 GeV2 confirming a long-standing prediction of the constituent quark model. The search for undiscovered but predicted states continues to be pursued with a vigorous experimental program. While recent data from Jefferson Lab and elsewhere provide intriguing hints of new states, final conclusions will have to wait for the results of the broad experimental effort currently underway with CLAS, and subsequent analyses involving the EBAC at Jefferson Lab.
Electroexcitation of nucleon resonances Aznauryan, I.G.; Burkert, V.D.
Progress in particle and nuclear physics,
2012, 2012-1-00, 2012-01-01, Volume:
67, Issue:
1
Journal Article
Peer reviewed
Open access
We review recent progress in the investigation of the electroexcitation of nucleon resonances, both in experiment and in theory. We describe current experimental facilities, the experiments performed ...on
π
and
η
electroproduction off protons, and theoretical approaches used for the extraction of resonance contributions from the experimental data. The status of
2
π
,
K
Λ
, and
K
Σ
electroproduction is also presented. The most accurate results have been obtained for the electroexcitation amplitudes of the four lowest excited states, which have been measured in a range of
Q
2
up to
8
and 4.5 GeV
2 for
Δ
(
1232
)
P
33
,
N
(
1535
)
S
11
and
N
(
1440
)
P
11
,
N
(
1520
)
D
13
, respectively. These results have been confronted with calculations based on lattice QCD, large-
N
c
relations, perturbative QCD (pQCD), and QCD-inspired models. The amplitudes for the
Δ
(
1232
)
indicate large pion-cloud contributions at low
Q
2
and do not show any sign of approaching the pQCD regime for
Q
2
<
7
GeV
2
. Measured for the first time, the electroexcitation amplitudes of the Roper resonance,
N
(
1440
)
P
11
, provide strong evidence for this state as a predominantly radial excitation of a three-quark (3
q
) ground state, with additional non-3-quark contributions needed to describe the low
Q
2
behavior of the amplitudes. The longitudinal transition amplitude for the
N
(
1535
)
S
11
was determined and has become a challenge for quark models. Explanations may require large meson-cloud contributions or alternative representations of this state. The
N
(
1520
)
D
13
clearly shows the rapid changeover from helicity-3/2 dominance at the real photon point to helicity-1/2 dominance at
Q
2
>
0.5
GeV
2
, confirming a long-standing prediction of the constituent quark model. The interpretation of the moments of resonance transition form factors in terms of transition transverse charge distributions in infinite momentum frame is presented.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Purpose. This study aims to analyze sensory fusion recovery using method of LCD glasses with alternating occlusion of visual fields and compare its efficacy with orthoptic treatment using ...synoptophore.Material and methods. Eighty-six patients with prior esotropia, post-operative absence of bifoveal fusion and residual angle of deviation <10° were studied. All patients were hyperopic. All of them underwent synoptophore treatment for 12 months (3–4 courses). Forty-three patients unsuccessful in bifoveal fusion recovery underwent treatment with LCD glasses for 6 hours/day.Results. Bifoveal fusion and binocular vision were significantly more often recovered (P<0,000) by LCD glasses treatment as compared to the synoptofore treatment. The stable bifoveal fusion was formed in 29 (67%) and 16 (18%) children, the unstable one – in 11 (26%) and 17 (20%); the treatment was ineffective in 3 (7%) and 53 (62%) patients, respectively. Binocular vision was obtained in 20 (46%) and 21 (24%) patients, and taking into account the subsequent diplopic treatment in cases with stable sensory fusion in 10 (23%) and 2 (2%), respectively. Parents were more satisfied with the treatment by LCD glasses because of the lack of frequent visits to the hospital.Conclusion. Alternating occlusion of visual fields with LCD glasses is a more effective mean of bifoveal fusion and binocular vision recovery than orthoptic treatment with a synoptophore in patients after successful strabismus surgery.
We utilize the light-front relativistic quark model to predict the 3q core contribution to the electroexcitation of nucleon resonances of the 70,1– multiplet on the proton and neutron at Q2 < 5 GeV2. ...The investigation is motivated by new experimental data from continuous electron beam accelerator facility large acceptance spectrometer on meson electroproduction for a wide range of the hadronic invariant mass including the full third nucleon resonance region up to √s = 1.8 GeV. For the states N(1520)3/2–, N(1535)1/2–, and N(1675)5/2–, experimental results on the electroexcitation amplitudes on the proton are available for a wide range of Q2. Lastly, this allowed us also to quantify the expected meson-baryon contributions to these amplitudes as a function of Q2.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
Цель. Оценκа эффеκтивности восстановления сенсорной фузии жидκоκристалличесκими (ЖК) очκами в сравнении с традиционным ортоптичесκим лечением на синоптофоре. Материал и методы. Пролечено 86 пациентов ...с оперированным содружественным сходящимся κосоглазием, остаточным углом κосоглазия до 10° и отсутствием сенсорной фузии. Все пациенты были с гиперметропичесκой рефраκцией. Сначала все пациенты прошли лечение на синоптофоре в течение 12 мес. κурсами по 10 дней (3-4 κурса). Сороκ три пациента, у κоторых сенсорная фузия не восстановилась, перешли на лечение ЖК очκами попеременным разобщением полей зрения постоянно в течение 6 часов в день. Результаты. Эффеκтивность восстановления сенсорной фузии и биноκулярного зрения была существенно (P<0,000) выше при лечении ЖК очκами по сравнению с синоптофором. Таκ, устойчивая сенсорная фузия сформировалась у 29 (67%) и 16 (18%) детей, неустойчивая - у 11 (26%) и 17 (20%); лечение было неэффеκтивным у 3 (7%) и 53 (62%) детей соответственно. Биноκулярное зрение было получено у 20 (46%) и 21 (24%) пациента, а с учетом последующего диплоптичесκого лечения при устойчивой сенсорной фузии у 10 (23%) и 2 (2%) пациентов соответственно. Наблюдалась большая удовлетворенность лечением родителей пациентов при лечении ЖК очκами из-за отсутствия необходимости частого посещения лечебного учреждения. Заκлючение. После проведенной хирургии κосоглазия в состоянии близκом κ ортотропии лечение методом попеременного разобщения полей зрения ЖК очκами является более эффеκтивным методом восстановления сенсорной фузии и биноκулярного зрения по сравнению с традиционным ортоптичесκим лечением на синоптофоре.
The transition γvpN* amplitudes (electrocouplings) for prominent excited nucleon states obtained in a wide area of photon virtualities offer valuable information for the exploration of the N* ...structure at different distances and allow us to access the complex dynamics of non-perturbative strong interaction. The current status in the studies of γvpN* electrocouplings from the data on exclusive meson electroproduction off protons measured with the CLAS detector at Jefferson Lab is presented. The impact of these results on exploration of the N* structure is discussed.
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