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Wolke, Magnus
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Publications (10 of 234) Show all publications
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
Anastasi, A., Babusci, D., Berlowski, M., Bloise, C., Bossi, F., Branchini, P., . . . Teubner, T. (2018). Combination of KLOE sigma (e(+) e(-) -> pi(+)pi(-) gamma(gamma)) measurements and determination of a(mu)(pi+pi-) in the energy range 0.10 < s < 0.95 GeV2. Journal of High Energy Physics (JHEP) (3), Article ID 173.
Open this publication in new window or tab >>Combination of KLOE sigma (e(+) e(-) -> pi(+)pi(-) gamma(gamma)) measurements and determination of a(mu)(pi+pi-) in the energy range 0.10 < s < 0.95 GeV2
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2018 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 3, article id 173Article in journal (Refereed) Published
Abstract [en]

The three precision measurements of the cross section sigma (e(+)e(-) -> pi(+)pi(-)gamma(gamma)) using initial state radiation by the KLOE collaboration provide an important input for the prediction of the hadronic contribution to the anomalous magnetic moment of the muon. These measurements are correlated for both statistical and systematic uncertainties and, therefore, the simultaneous use of these measurements requires covariance matrices that fully describe the correlations. We present the construction of these covariance matrices and use them to determine a combined KLOE measurement for sigma (e(+)e(-) -> pi(+)pi(-)gamma(gamma)). We find, from this combination, a two-pion contribution to the muon magnetic anomaly in the energy range 0.10 < s < 0.95 GeV2 of a(mu)(pi+pi-) (489.8 +/- 1.7(stat) +/- 4.8(sys)) x 10(-10).

Place, publisher, year, edition, pages
Springer, 2018
Keywords
e plus -e- Experiments
National Category
Subatomic Physics Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-351704 (URN)10.1007/JHEP03(2018)173 (DOI)000429243600001 ()
Available from: 2018-06-04 Created: 2018-06-04 Last updated: 2018-06-04Bibliographically approved
Anastasi, A., Babusci, D., Berlowski, M., Bloise, C., Bossi, F., Branchini, R., . . . Wolke, M. (2018). Combined limit on the production of a light gauge boson decaying into mu(+) mu(-) and pi(+) pi(-). Physics Letters B, 784, 336-341
Open this publication in new window or tab >>Combined limit on the production of a light gauge boson decaying into mu(+) mu(-) and pi(+) pi(-)
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2018 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 784, p. 336-341Article in journal (Refereed) Published
Abstract [en]

We searched for the mu(+) mu(-) decay of a light vector gauge boson, also known as dark photon, in the e(+) e(-) -> mu(+) mu(-) gamma(ISR) process by means of the Initial State Radiation (ISR) method. We used 1.93fb(-1) of data collected by the KLOE experiment at the DA Phi NE phi-factory. No structures have been observed over the irreducible mu(+) mu(-) background. A 90% CL limit on the ratio epsilon(2)= alpha'/alpha between the dark coupling constant and the fine structure constant of 3 x 10(-6)-2 x 10(-7) has been set in the dark photon mass region between 519 MeV and 973 MeV. This new limit has been combined with the published result obtained investigating the hypothesis of the dark photon decaying into hadrons in e(+) e(-) -> pi(+) pi(-) gamma(ISR) events. The combined 90% CL limit increases the sensitivity especially in the rho-omega interference region and excludes epsilon(2) greater than (13 - 2) x 10(-7). For dark photon masses greater than 600 MeV the combined limit is lower than 8 x 10(-7) resulting more stringent than present constraints from other experiments.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
e(+) e(-) Collisions, Dark forces, Gauge vector boson, Upper limits
National Category
Subatomic Physics Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:uu:diva-368113 (URN)10.1016/j.physletb.2018.08.012 (DOI)000445781600051 ()
Available from: 2018-12-06 Created: 2018-12-06 Last updated: 2018-12-06Bibliographically approved
Ablikim, M., Achasov, M. N., Ai, X. C., Ambrose, D. J., Amoroso, A., An, F. F., . . . Zou, J. H. (2018). Determination of the number of ψ(3686) events at BESIII. Chinese Physics C, High Energy Physics & Nuclear Physics, 42(2), Article ID 023001.
Open this publication in new window or tab >>Determination of the number of ψ(3686) events at BESIII
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2018 (English)In: Chinese Physics C, High Energy Physics & Nuclear Physics, ISSN 1674-1137, E-ISSN 0899-9996, Vol. 42, no 2, article id 023001Article in journal (Refereed) Published
Abstract [en]

The numbers of psi(3686) events accumulated by the BESIII detector for the data taken during 2009 and 2012 are determined to be (107.0 +/- 0.8)x10(6) and (341.1 +/- 2.1)x10(6), respectively, by counting inclusive hadronic events, where the uncertainties are systematic and the statistical uncertainties are negligible. The number of events for the sample taken in 2009 is consistent with that of the previous measurement. The total number of psi(3686) events for the two data taking periods is (448.1 +/- 2.9) x 10(6).

Keywords
psi(3686), inclusive process, hadronic events, Bhabha process
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-351110 (URN)10.1088/1674-1137/42/2/023001 (DOI)000427537400001 ()
Funder
Swedish Research CouncilGerman Research Foundation (DFG)
Note

Uppsala Universitet affiliering, antagligen felaktig på: Zhao, S.J & Li, D.M.

Troligen Uppsala Universitet affiliering på Kupsc, Andrzej; Schönning, Karin & Wolke, Magnus.

Available from: 2018-05-29 Created: 2018-05-29 Last updated: 2018-05-29Bibliographically approved
Ablikim, M., Achasov, M. N., Ahmed, S., Albrecht, M., Alekseev, M., Amoroso, A., . . . Zou, J. H. (2018). First measurement of e(+)e(-) -> pK(S)(0)(n)over-barK(-) + c.c. above open charm threshold. Physical Review D: covering particles, fields, gravitation, and cosmology, 98(3), Article ID 032014.
Open this publication in new window or tab >>First measurement of e(+)e(-) -> pK(S)(0)(n)over-barK(-) + c.c. above open charm threshold
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2018 (English)In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 98, no 3, article id 032014Article in journal (Refereed) Published
Abstract [en]

The process e(+)e(-) -> pK(S)(0)(n) over barK(-) + c.c. and its intermediate processes are studied for the first time, using data samples collected with the BESIII detector at BEPCII at center-of-mass energies of 3.773, 4.008, 4.226, 4.258, 4.358, 4.416, and 4.600 GeV, with a total integrated luminosity of 7.4 fb(-1). The Born cross section of e(+)e(-) -> pK(S)(0)(n) over barK(-) + c.c. is measured at each center-of-mass energy, but no significant resonant structure in the measured cross-section line shape between 3.773 and 4.600 GeV is observed. No evident structure is detected in the pK(-), nK(S)(0), pK(S)(0), nK(+), p (n) over bar, or (KSK-)-K-0 invariant mass distributions except for Lambda(1520). The Born cross sections of e(+)e(-) -> Lambda(1520)(n) over barK(S)(0) + c.c. and e(+)e(-) -> Lambda(1520)(p) over barK(+) + c.c. are measured, and the 90% confidence level upper limits on the Born cross sections of e(+)e(-) -> Lambda(1520)(Lambda) over bar (1520) are determined at the seven center-of-mass energies. There is an evident difference in line shape and magnitude of the measured cross sections between e(+)e(-) -> Lambda(1520)(-> pK(-))(n) over barK(S)(0) and e(+)e(-) -> pK-(Lambda) over bar (1520)(-> (n) over barK(S)(0)).

National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-364204 (URN)10.1103/PhysRevD.98.032014 (DOI)000442883200002 ()
Funder
Swedish Research CouncilGerman Research Foundation (DFG)
Available from: 2018-10-25 Created: 2018-10-25 Last updated: 2018-10-25Bibliographically 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
Ablikim, M., Achasov, M. N., Ahmed, S., Albrecht, M., Alekseev, M., Amoroso, A., . . . Zou, J. H. (2018). Improved measurements of X-cJ -> Sigma(+) (Sigma)over-bar(-) and Sigma(0)(Sigma)over-bar(0) decays. Physical Review D: covering particles, fields, gravitation, and cosmology, 97(5), Article ID 052011.
Open this publication in new window or tab >>Improved measurements of X-cJ -> Sigma(+) (Sigma)over-bar(-) and Sigma(0)(Sigma)over-bar(0) decays
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2018 (English)In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 97, no 5, article id 052011Article in journal (Refereed) Published
Abstract [en]

Using a data sample of (448.1 +/- 2.9) x 10(6) psi (3686) events collected with the BESIII detector at the BEPCII collider, we present measurements of branching fractions for the decays X-cJ -> Sigma(+) (Sigma) over bar (-) and Sigma(0) (Sigma) over bar (0) The decays X-c1.2 -> Sigma(+) (Sigma) over bar (-) and Sigma (Sigma) over bar (0) are observed for the first time, and the branching fractions for X-c0 -> Sigma(+) (Sigma) over bar (-) and Sigma(0) (Sigma) over bar (0) decays are measured with improved precision. The branching fraction ratios between the charged and neutral modes are consistent with the prediction of isospin symmetry.

Place, publisher, year, edition, pages
American Physical Society, 2018
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-352724 (URN)10.1103/PhysRevD.97.052011 (DOI)000428505700001 ()
Funder
Swedish Research Council
Available from: 2018-06-07 Created: 2018-06-07 Last updated: 2018-06-07Bibliographically 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?