uu.seUppsala University Publications
Change search
Link to record
Permanent link

Direct link
BETA
Thörngren Engblom, Pia
Alternative names
Publications (10 of 13) Show all publications
Bashkanov, M., Calèn, H., Cappellaro, F., Ekström, C., Fransson, K., Gustafsson, L., . . . Zlomanczuk, J. (2007). Low-mass pi pi enhancement in baryonic pi pi production: ABC effect revised by exclusive measurements. International Journal of Modern Physics A, 22(2-3), 625-628
Open this publication in new window or tab >>Low-mass pi pi enhancement in baryonic pi pi production: ABC effect revised by exclusive measurements
Show others...
2007 (English)In: International Journal of Modern Physics A, ISSN 0217-751X, E-ISSN 1793-656X, Vol. 22, no 2-3, p. 625-628Article in journal (Refereed) Published
Abstract [en]

The ABC effect - a puzzling threshold enhancement in the ππ invariant mass spectrum of double-pionic fusion to nuclear bound states - has been investigated since 40 years by inclusive measurements without providing a conclusive interpretation. First exclusive measurements to this topic have now been carried out at CELSIUS-WASA. They confirm a huge ππ threshold enhancement, prove it to be of scalar-isoscalar nature, i.e., a σ-channel phenomenon and reveal the theoretically predicted high-mass enhancement in inclusive spectra to be of πππ rather than of ππ nature - falsifying thus corresponding model predictions for the ABC effect. From the kinematically complete data samples we infer that the interaction between the two Δ particles created in this process is of crucial importance.

Keywords
ABC effect, σ channel enhancement, ∆∆ interaction, medium effects
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-16890 (URN)10.1142/S0217751X07035987 (DOI)000250926800065 ()
Available from: 2008-06-16 Created: 2008-06-16 Last updated: 2017-12-08Bibliographically approved
Khakimova, O., Calèn, H., Cappellaro, F., Ekström, C., Fransson, K., Gustafsson, L., . . . Zlomanczuk, J. (2007). Observation of the abc effect in the first exclusive measurements of pn -> d pi(0)pi(0). International Journal of Modern Physics A, 22(2-3), 617-620
Open this publication in new window or tab >>Observation of the abc effect in the first exclusive measurements of pn -> d pi(0)pi(0)
Show others...
2007 (English)In: International Journal of Modern Physics A, ISSN 0217-751X, E-ISSN 1793-656X, Vol. 22, no 2-3, p. 617-620Article in journal (Refereed) Published
Abstract [en]

The reaction pn → dπ0π0 constitutes the most fundamental system for the study of the ABC effect - a puzzling threshold enhancement in the ππ invariant mass spectrum of the ππ system in double-pionic fusion to nuclear bound states. The first exclusive measurements of this reaction have now been carried out at CELSIUS-WASA. They exhibit a striking low-mass enhancement in the ππ invariant mass spectrum, prove it to be a σ-channel phenomenon and falsify conventional theoretical models, which predict an associated high-mass enhancement not present in the new exclusive data. In the kinematically complete data sample we observe a ΔΔ excitation, where the interaction between the two Δ obviously plays a crucial role for the generation of the ππ low-mass enhancement.

Keywords
ABC effect, σ channel enhancement, ΔΔ interaction, medium effects
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-16891 (URN)10.1142/S0217751X07035963 (DOI)000250926800063 ()
Available from: 2008-06-16 Created: 2008-06-16 Last updated: 2017-12-08Bibliographically approved
Skorodko, T., Calèn, H., Cappellaro, F., Ekström, C., Fransson, K., Greiff, J., . . . Zlomanczuk, J. (2007). pi pi production in proton-proton collisions. International Journal of Modern Physics A, 22(2-3), 509-513
Open this publication in new window or tab >>pi pi production in proton-proton collisions
Show others...
2007 (English)In: International Journal of Modern Physics A, ISSN 0217-751X, E-ISSN 1793-656X, Vol. 22, no 2-3, p. 509-513Article in journal (Refereed) Published
Abstract [en]

At CELSIUS-WASA the two-pion production in proton-proton collisisons has been measured exclusively from threshold up to the energy regime, where both of the collision partners are expected to be excited to the Δ state. The measurements constitute the first kinematically complete data samples of solid statistics in this energy range. Most of the data have been obtained for the π+π- and π0π0channels. Whereas at near-threshold energies the differential distributions can be succesfully explained by chiral dynamics and Roper excitation, respectively, the data for the π+π- channel in the ΔΔ region can be described only, if the special configuration (ΔΔ)0+ is assumed. The data for the π0π0 channel moreover exhibit a low-mass enhancement in the π0π0 invariant mass spectrum, which is reminiscent of the ABC-effect found in double-pionic fusion to light nuclei.

Keywords
Roper excitation, ΔΔ excitation, σ channel enhancement, ABC effect, ππ interaction
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-16892 (URN)10.1142/S0217751X07035720 (DOI)000250926800039 ()
Available from: 2008-06-16 Created: 2008-06-16 Last updated: 2017-12-08Bibliographically approved
Pauly, C., Jacewicz, M., Koch, I., Calen, H., Capellaro, F., Fransson, K., . . . Zlomanczuk, J. (2007). The p p -> p p pi pi pi reaction channels in the threshold region.
Open this publication in new window or tab >>The p p -> p p pi pi pi reaction channels in the threshold region
Show others...
2007 (English)Report (Other scientific)
Series
e-Print ; nucl-ex/0602006
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-22824 (URN)
Available from: 2007-01-22 Created: 2007-01-22
Pauly, C., Jacewicz, M., Koch, I., Bashkanov, M., Bogoslawsky, D., Calén, H., . . . Zlomanczuk, J. (2007). The pp→ppπππ reaction channels in the threshold region. Physics Letters B, 649(2-3), 122-127
Open this publication in new window or tab >>The ppppπππ reaction channels in the threshold region
Show others...
2007 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 649, no 2-3, p. 122-127Article in journal (Refereed) Published
Abstract [en]

The cross section for direct neutral and charged three pion production in pp interactions was measured at excess energies in the range 160–216 MeV. That comprises the first measurement of the ppppπ0π0π0 reaction and the direct comparison with the ppppπ+ππ0 process. The experiment was performed above the η meson production threshold and the cross section could be directly normalized to the cross section of the ppppη reaction, with the η decaying into 3 pions. Since the same final states are selected, the measurement has a low systematical error. The measured cross section ratio σ(ppppπ+ππ0)/σ(ppppπ0π0π0) is compared to predictions of dominance of different isobars in the intermediate state.

Keywords
Threshold measurement, Three pion production, Final state interaction
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-16830 (URN)10.1016/j.physletb.2007.04.004 (DOI)000247170700003 ()
Available from: 2008-06-16 Created: 2008-06-16 Last updated: 2017-12-08Bibliographically approved
Calen, H., Fransson, K., Gustafsson, L., Hoistad, B., Jacewicz, M., Johansson, T., . . . Zlomanczuk, J. (2006). Evidence for a 'Narrow' Roper Resonance - The Breathing Mode of the Nucleon.
Open this publication in new window or tab >>Evidence for a 'Narrow' Roper Resonance - The Breathing Mode of the Nucleon
Show others...
2006 (English)Report (Other scientific)
Series
e-Print arXiv ; nucl-ex/0612015
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-23534 (URN)
Available from: 2007-01-30 Created: 2007-01-30
Calen, H., Fransson, K., Gustafsson, L., Hoistad, B., Jacewicz, M., Johansson, T., . . . Zlomanczuk, J. (2006). Measurement of the eta->pi+ pi- e+ e- decay branching ration.
Open this publication in new window or tab >>Measurement of the eta->pi+ pi- e+ e- decay branching ration
Show others...
2006 (English)Report (Other scientific)
Series
e-Print arXiv ; hep-ex/0609007
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-23535 (URN)
Available from: 2007-01-30 Created: 2007-01-30
Calen, H., Fransson, K., Gustafsson, L., Hoistad, B., Jacewicz, M., Johansson, T., . . . Zlomanczuk, J. (2006). On the pipi production in free and in-medium NN-collisions: sigma-channel low-mass enhancement and pi0pi0/pi+pi- asymmetry. Acta Physica Slovaca, 56(3), 285-297
Open this publication in new window or tab >>On the pipi production in free and in-medium NN-collisions: sigma-channel low-mass enhancement and pi0pi0/pi+pi- asymmetry
Show others...
2006 (English)In: Acta Physica Slovaca, Vol. 56, no 3, p. 285-297Article in journal (Refereed) Published
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-22155 (URN)
Available from: 2007-01-11 Created: 2007-01-11 Last updated: 2011-01-11
Calen, H., Fransson, K., Gustafsson, L., Hoistad, B., Jacewicz, M., Johansson, T., . . . Zlomanczuk, J. (2006). Two-Pion Production in Nucleon-Nucleon Collisions and the ABC Effect - Approaching a Puzzle by Exclusive and Kinematically Complete Measurements.
Open this publication in new window or tab >>Two-Pion Production in Nucleon-Nucleon Collisions and the ABC Effect - Approaching a Puzzle by Exclusive and Kinematically Complete Measurements
Show others...
2006 (English)Report (Other (popular scientific, debate etc.))
Series
e-Print arXiv ; nucl-ex/0612016
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-23533 (URN)
Available from: 2007-01-30 Created: 2007-01-30
Cappellaro, F., Johansson, T., Gustafsson, L., Hoistad, B., Jacewicz, M., Keleta, S., . . . Ruber, R. (2005). EXCLUSIVE MEASUREMENTS OF PD ---> HE-3 PI PI: THE ABC EFFECT REVISITED.
Open this publication in new window or tab >>EXCLUSIVE MEASUREMENTS OF PD ---> HE-3 PI PI: THE ABC EFFECT REVISITED
Show others...
2005 (English)Other (Other scientific)
Publisher
p. 4
Series
e-Print Archive ; nucl-ex/0508011
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-77333 (URN)
Available from: 2007-04-17 Created: 2007-04-17
Organisations

Search in DiVA

Show all publications