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BETA
Calén, Hans
Alternative names
Publications (10 of 85) Show all publications
Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berlowski, M., . . . Zurek, M. (2019). Examination of the production of an isotensor dibaryon in the pp -> pp pi(+)pi(-) reaction. Physical Review C: Covering Nuclear Physics, 99(2), Article ID 025201.
Open this publication in new window or tab >>Examination of the production of an isotensor dibaryon in the pp -> pp pi(+)pi(-) reaction
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2019 (English)In: Physical Review C: Covering Nuclear Physics, ISSN 2469-9985, E-ISSN 2469-9993, Vol. 99, no 2, article id 025201Article in journal (Refereed) Published
Abstract [en]

The quasifree pp -> pp pi(+)pi(-) reaction has been measured by means of pd collisions at T-p = 1.2 GeV using the WASA detector setup at COSY enabling exclusive and kinematically complete measurements. Total and differential cross sections have been extracted for the energy region T-p = 1.08-1.36 GeV (root s = 2.35-2.46 GeV) covering thus the regions of N* (1440 ) and Delta(1232)Delta(1232) resonance excitations. Calculations describing these excitations by t-channel meson exchange as well as isospin relations based on the pp -> pp pi(0)pi(0) data underpredict substantially the measured total cross section. The calculations are also at variance with specific experimental differential cross sections. An isotensor Delta N dibaryon resonance with I(J(P)) = 2(1(+) ) produced associatedly with a pion is able to overcome these deficiencies. Such a dibaryon was predicted by Dyson and Xuong [Phys. Rev. Lett. 13, 815 (1964)] and more recently calculated by A. Gal and H. Garcilazo [Nucl. Phys. A 928, 73 (2014)].

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2019
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-377601 (URN)10.1103/PhysRevC.99.025201 (DOI)000457696100003 ()
Available from: 2019-02-26 Created: 2019-02-26 Last updated: 2019-03-07Bibliographically approved
Barucca, G., Martin, A., Akram, A., Calén, H., Andersson, W. I., Johansson, T., . . . Zmeskal, J. (2019). Precision resonance energy scans with the PANDA experiment at FAIR: Sensitivity study for width and line shape measurements of the X(3872). European Physical Journal A, 55(3), Article ID 42.
Open this publication in new window or tab >>Precision resonance energy scans with the PANDA experiment at FAIR: Sensitivity study for width and line shape measurements of the X(3872)
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2019 (English)In: European Physical Journal A, ISSN 1434-6001, E-ISSN 1434-601X, Vol. 55, no 3, article id 42Article in journal (Refereed) Published
Abstract [en]

This paper summarises a comprehensive Monte Carlo simulation study for precision resonance energy scan measurements. Apart from the proof of principle for natural width and line shape measurements of very narrow resonances with PANDA, the achievable sensitivities are quantified for the concrete example of the charmonium-like X(3872) state discussed to be exotic, and for a larger parameter space of various assumed signal cross-sections, input widths and luminosity combinations. PANDA is the only experiment that will be able to perform precision resonance energy scans of such narrow states with quantum numbers of spin and parities that differ from JPC=1--.

Place, publisher, year, edition, pages
SPRINGER, 2019
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-381575 (URN)10.1140/epja/i2019-12718-2 (DOI)000462672600001 ()
Funder
EU, FP7, Seventh Framework Programme, HP3 GA283286Swedish Research CouncilKnut and Alice Wallenberg Foundation
Note

For complete list of authors see http://dx.doi.org/10.1140/epja/i2019-12718-2

Available from: 2019-04-12 Created: 2019-04-12 Last updated: 2019-04-12Bibliographically approved
Singh, B., Calén, H., Andersson, W. I., Johansson, T., Kupsc, A., Marciniewski, P., . . . Zmeskal, J. (2019). Technical design report for the (P)over-barANDA Barrel DIRC detector. Journal of Physics G: Nuclear and Particle Physics, 46(4), Article ID 045001.
Open this publication in new window or tab >>Technical design report for the (P)over-barANDA Barrel DIRC detector
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2019 (English)In: Journal of Physics G: Nuclear and Particle Physics, ISSN 0954-3899, E-ISSN 1361-6471, Vol. 46, no 4, article id 045001Article in journal (Refereed) Published
Abstract [en]

The (P) over bar ANDA (anti-Proton ANnihiliation at DArmstadt) experiment will be one of the four flagship experiments at the new international accelerator complex FAIR (Facility for Antiproton and Ion Research) in Darmstadt, Germany. (P) over bar ANDA will address fundamental questions of hadron physics and quantum chromodynamics using high-intensity cooled antiproton beams with momenta between 1.5 and 15 GeV/c and a design luminosity of up to 2 x 10(32) cm(-2) S-1. Excellent particle identification (PID) is crucial to the success of the (P) over bar ANDA physics program. Hadronic PID in the barrel region of the target spectrometer will be performed by a fast and compact Cherenkov counter using the detection of internally reflected Cherenkov light (DIRC) technology. It is designed to cover the polar angle range from 22 degrees to 140 degrees and will provide at least 3 standard deviations (s.d.) pi/K separation up to 3.5 GeV/c, matching the expected upper limit of the final state kaon momentum distribution from simulation. This documents describes the technical design and the expected performance of the (P) over bar ANDA Barrel DIRC detector. The design is based on the successful BaBar DIRC with several key improvements. The performance and system cost were optimized in detailed detector simulations and validated with full system prototypes using particle beams at GSI and CERN. The final design meets or exceeds the PID goal of clean pi/K separation with at least 3 s.d. over the entire phase space of charged kaons in the Barrel DIRC.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2019
Keywords
particle identification, ring imaging Cherenkov detector, DIRC counter, PANDA experiment, hadron physics
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-379882 (URN)10.1088/1361-6471/aade3d (DOI)000460153900001 ()
Funder
EU, FP7, Seventh Framework Programme, 227431
Note

For complete list of authors see http://dx.doi.org/10.1088/1361-6471/aade3d

Available from: 2019-03-25 Created: 2019-03-25 Last updated: 2019-03-25Bibliographically approved
Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berlowski, M., . . . Wilkin, C. (2018). Backward single-pion production in the pd -> He-3 pi(0)reaction with WASA-at-COSY. European Physical Journal A, 54(9), Article ID 149.
Open this publication in new window or tab >>Backward single-pion production in the pd -> He-3 pi(0)reaction with WASA-at-COSY
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2018 (English)In: European Physical Journal A, ISSN 1434-6001, E-ISSN 1434-601X, Vol. 54, no 9, article id 149Article in journal (Refereed) Published
Abstract [en]

New data on the production of single neutral pions in the pd -> He-3 pi(0) reaction are presented. For fifteen proton beam momenta between p(p) = 1.60GeV/c and p(p) = 1.74 GeV/c, differential cross sections are determined over a large fraction of the backward hemisphere. Since the only previous systematic measurements of single-pion production at these energies were made in collinear kinematics, the present work constitutes a significant extension of the current knowledge on this reaction. Even this far above the production threshold, significant changes are found in the behaviour of the angular distributions over small intervals in beam momentum.

Place, publisher, year, edition, pages
SPRINGER, 2018
National Category
Astronomy, Astrophysics and Cosmology Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-366738 (URN)10.1140/epja/i2018-12585-3 (DOI)000444638600001 ()
Funder
EU, FP7, Seventh Framework Programme, 283286
Available from: 2018-12-10 Created: 2018-12-10 Last updated: 2018-12-10Bibliographically approved
Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berlowski, M., . . . Zurek, M. (2018). Importance of d-wave contributions in the charge symmetry breaking reaction dd -> He-4 pi(0). Physics Letters B, 781, 645-650
Open this publication in new window or tab >>Importance of d-wave contributions in the charge symmetry breaking reaction dd -> He-4 pi(0)
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2018 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 781, p. 645-650Article in journal (Refereed) Published
Abstract [en]

This letter reports a first quantitative analysis of the contribution of higher partial waves in the charge symmetry breaking reaction dd -> He-4 pi(0) using the WASA-at-COSY detector setup at an excess energy of Q = 60 MeV. The determined differential cross section can be parametrized as d sigma/d Omega = a + b cos(2) theta*, where theta* is the production angle of the pion in the center-of-mass coordinate system, and the results for the parameters are a = (1.55 +/- 0.46(stat)(-0.8)(+0.32)(syst)) pb/sr and b = (13.1 +/- 2.1(stat)(-2.7)(+1.0)(syst)) pb/sr. The data are compatible with vanishing p-waves and a sizable d-wave contribution. This finding should strongly constrain the contribution of the A isobar to the dd -> He-4 pi(0) reaction and is, therefore, crucial for a quantitative understanding of quark mass effects in nuclear production reactions.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
Charge symmetry breaking, Deuteron deuteron interactions, Pion production
National Category
Subatomic Physics Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-358693 (URN)10.1016/j.physletb.2018.04.037 (DOI)000435653100082 ()
Funder
EU, FP7, Seventh Framework Programme, 227431Swedish Research CouncilKnut and Alice Wallenberg Foundation
Available from: 2018-09-05 Created: 2018-09-05 Last updated: 2018-09-05Bibliographically approved
Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berlowski, M., . . . Zurek, M. (2018). Isotensor Dibaryon in the pp -> pp pi(+)pi(-) Reaction?. Physical Review Letters, 121(5), Article ID 052001.
Open this publication in new window or tab >>Isotensor Dibaryon in the pp -> pp pi(+)pi(-) Reaction?
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2018 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 121, no 5, article id 052001Article in journal (Refereed) Published
Abstract [en]

Exclusive measurements of the quasifree pp -> pp pi(+)pi(-) reaction have been carried out at WASA@ COSY by means of pd collisions at T-p = 1.2 GeV. Total and differential cross sections have been extracted covering the energy region T-p = 1.08-1.36 GeV, which is the region of N* (1440) and Delta(123)Delta(1232) resonance excitations. Calculations describing these excitations by t-channel meson exchange are at variance with the measured differential cross sections and underpredict substantially the experimental total cross section. An isotensor Delta N dibaryon resonance with I(J(P)) = 2(1(+)) produced associatedly with a pion is able to overcome these deficiencies.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2018
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-362841 (URN)10.1103/PhysRevLett.121.052001 (DOI)000440415600003 ()30118290 (PubMedID)
Funder
German Research Foundation (DFG), CL 214/3-2
Available from: 2018-10-15 Created: 2018-10-15 Last updated: 2018-10-15Bibliographically approved
Adlarson, P., Collaboration, W.-a., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., . . . Wirzba, A. (2018). Search for C violation in the decay eta -> pi(0)e(+)e(-) with WASA-at-COSY. Physics Letters B, 784, 378-384
Open this publication in new window or tab >>Search for C violation in the decay eta -> pi(0)e(+)e(-) with WASA-at-COSY
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2018 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 784, p. 378-384Article in journal (Refereed) Published
Abstract [en]

We report on the search for the rare decay eta -> pi(0)e(+)e(-) which is of interest to study C violation in the electromagnetic interaction which would indicate contributions from physics beyond the Standard Model, since the allowed decay via a two-photon intermediate state is strongly suppressed. The experiment has been performed using the WASA-at-COSY installation, located at the COSY accelerator of the Forschungszentrum Julich, Germany. In total 3 x 10(7) events of the reaction pd -> He-3 eta have been recorded at an excess energy of Q = 59.8MeV. Based on this data set the C parity violating decay eta -> pi(0)gamma* -> pi(0)e(+)e(-) via a single-photon intermediate state has been searched for, resulting in new upper limits of Gamma(eta -> pi(0)e(+) e(-))/Gamma(eta -> pi(+) pi(-) pi(0)) < 3.28 x 10(-5) and Gamma(eta -> pi(0)e(+) e(-))/Gamma(eta -> all)< 7.5 x 10(-6) (CL=90%), respectively. 

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
National Category
Subatomic Physics Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-368116 (URN)10.1016/j.physletb.2018.07.017 (DOI)000445781600056 ()
Funder
EU, FP7, Seventh Framework Programme, 227431Swedish Research CouncilKnut and Alice Wallenberg Foundation
Available from: 2018-12-06 Created: 2018-12-06 Last updated: 2018-12-06Bibliographically approved
Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bass, S. D., Bergmann, F. S., . . . Zurek, M. (2018). Spin Dependence of eta Meson Production in Proton-Proton Collisions Close to Threshold. Physical Review Letters, 120(2), Article ID 022002.
Open this publication in new window or tab >>Spin Dependence of eta Meson Production in Proton-Proton Collisions Close to Threshold
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2018 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 120, no 2, article id 022002Article in journal (Refereed) Published
Abstract [en]

Taking advantage of the high acceptance and axial symmetry of the WASA-at-COSY detector, and the high polarization degree of the proton beam of COSY, the reaction →pp→ppη has been measured close to threshold to explore the analyzing power Ay. The angular distribution of Ay is determined with the precision improved by more than 1 order of magnitude with respect to previous results, allowing a first accurate comparison with theoretical predictions. The determined analyzing power is consistent with zero for an excess energy of Q=15  MeV, signaling s-wave production with no evidence for higher partial waves. At Q=72  MeV the data reveal strong interference of Ps and Pp partial waves and cancellation of (Pp)2 and Ss∗Sd contributions. These results rule out the presently available theoretical predictions for the production mechanism of the η meson.

National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-341490 (URN)10.1103/PhysRevLett.120.022002 (DOI)000419478800004 ()
Available from: 2018-02-21 Created: 2018-02-21 Last updated: 2018-02-21Bibliographically approved
Adlarson, P., Augustyniak, W., Bardan, W., Bashkanov, M., Bergmann, F. S., Berlowski, M., . . . Wilkin, C. (2018). Total and differential cross sections of η-production in proton–deuteron fusion for excess energies between Qη = 13 MeV and Qη = 81 MeV. Physics Letters B, 782, 297-304
Open this publication in new window or tab >>Total and differential cross sections of η-production in proton–deuteron fusion for excess energies between Qη = 13 MeV and Qη = 81 MeV
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2018 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 782, p. 297-304Article in journal (Refereed) Published
Abstract [en]

New data on both total and differential cross sections of the production of eta mesons in proton-deuteron fusion to He-3 eta in the excess energy region 13.6 MeV <= Q(eta) <= 80.9 MeV are presented. These data have been obtained with the WASA-at-COSY detector setup located at the Forschungszentrum Julich, using a proton beam at 15 different beam momenta between p(p) = 1.60 GeV/c and p(p) = 1.74 GeV/c. While significant structure of the total cross section is observed in the energy region 20 MeV less than or similar to Q(eta) less than or similar to 60 MeV, a previously reported sharp variation around Q(eta) approximate to 50 MeV cannot be confirmed. Angular distributions show the typical forward- peaking that was noted earlier. For the first time, it is possible to study the development of these angular distributions with rising excess energy over a wide interval.

Keywords
Meson production, Proton-deuteron interactions, eta meson
National Category
Subatomic Physics Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-361529 (URN)10.1016/j.physletb.2018.05.036 (DOI)000438486900050 ()
Funder
EU, FP7, Seventh Framework Programme, 283286German Research Foundation (DFG), GRK2149
Note

WoS title: Total and differential cross sections of eta-production in proton-deuteron fusion for excess energies between Q(eta)=13 MeV and Q(eta)=81 MeV

Available from: 2018-09-25 Created: 2018-09-25 Last updated: 2018-12-21Bibliographically approved
Singh, B., Erni, W., Krusche, B., Steinacher, M., Walford, N., Liu, H., . . . Semenov-Tian-Shansky, K. M. (2017). Feasibility study for the measurement of pi N transition distribution amplitudes at (P)over-barANDA in (P)over-barp -> J/psi pi(0). Physical Review D: covering particles, fields, gravitation, and cosmology, 95(3), Article ID 032003.
Open this publication in new window or tab >>Feasibility study for the measurement of pi N transition distribution amplitudes at (P)over-barANDA in (P)over-barp -> J/psi pi(0)
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2017 (English)In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 95, no 3, article id 032003Article in journal (Refereed) Published
Abstract [en]

The exclusive charmonium production process in (P) over barp annihilation with an associated pi 0 meson (p) over barp -> J/psi pi(0) is studied in the framework of QCD collinear factorization. The feasibility of measuring this reaction through the J/psi -> e(+) e(-) decay channel with the AntiProton ANnihilation at DArmstadt ((P) over bar ANDA) experiment is investigated. Simulations on signal reconstruction efficiency as well as the background rejection from various sources including the (P) over barp -> pi(+)pi(-)pi(0) and (p) over barp -> J/psi pi(0)pi(0) reactions are performed with PANDAROOT, the simulation and analysis software framework of the (P) over bar ANDA experiment. It is shown that the measurement can be done at (P) over bar ANDA with significant constraining power under the assumption of an integrated luminosity attainable in four to five months of data taking at the maximum design luminosity.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2017
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-319567 (URN)10.1103/PhysRevD.95.032003 (DOI)000393744600003 ()
Funder
German Research Foundation (DFG)Swedish Research Council
Available from: 2017-04-06 Created: 2017-04-06 Last updated: 2017-11-29Bibliographically approved
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