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Caldeira Balkeståhl, Li
Alternative names
Publications (10 of 58) Show all publications
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., Bencivenni, G., Berlowski, M., Bloise, C., Bossi, F., . . . Jegerlehner, F. (2017). Measurement of the running of the fine structure constant below 1 GeV with the KLOE detector. Physics Letters B, 767, 485-492
Open this publication in new window or tab >>Measurement of the running of the fine structure constant below 1 GeV with the KLOE detector
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2017 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 767, p. 485-492Article in journal (Refereed) Published
Abstract [en]

We have measured the running of the effective QED coupling constant alpha(s) in the time-like region 0.6 < root s < 0.975 GeV with the KLOE detector at DA Phi NE using the Initial-State Radiation process e(+) e(-) -> mu(+) mu(-)gamma. It represents the first measurement of the running of alpha(s) in this energy region. Our results show a more than 5 sigma significance of the hadronic contribution to the running of alpha(s), which is the strongest direct evidence both in time- and space-like regions achieved in a single measurement. By using the e(+) e(-) -> pi(+) pi(-) cross section measured by KLOE, the real and imaginary parts of the shift Delta alpha(s) have been extracted. From a fit of the real part of Delta alpha(s) and assuming the lepton universality the branching ratio BR(omega -> mu(+) mu(-)) = (6.6 +/- 1.4(stat) +/- 1.7(syst)) (.) 10 (5)has been determined.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2017
Keywords
Vacuum polarization, arunning
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-320023 (URN)10.1016/j.physletb.2016.12.016 (DOI)000397861700074 ()
Funder
EU, FP7, Seventh Framework Programme, FP7-INFRASTRUCTURES2008-1 227431
Note

A KLOE-2 Collaboration

Available from: 2017-04-13 Created: 2017-04-13 Last updated: 2017-11-29Bibliographically approved
Ablikim, M., Achasov, M. N., Ahmed, S., Albrecht, M., Amoroso, A., An, F. F., . . . Zou, J. H. (2017). Observation of χc2→η′η′ and χc0,2→ηη′. Physical Review D: covering particles, fields, gravitation, and cosmology, 96(11), Article ID 112006.
Open this publication in new window or tab >>Observation of χc2η′η′ and χc0,2ηη′
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2017 (English)In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 96, no 11, article id 112006Article in journal (Refereed) Published
Abstract [en]

Using a sample of 448.1×106 ψ(3686) events collected with the BESIII detector in 2009 and 2012, we study the decays χc0,2η′η′ and ηη′. The decays χc2η′η′, χc0ηη′ and χc2ηη′ are observed for the first time with statistical significances of 9.6σ, 13.4σ and 7.5σ, respectively. The branching fractions are determined to be Bc0η′η′)=(2.19±0.03±0.14)×10−3, Bc2η′η′)=(4.76±0.56±0.38)×10−5, Bc0ηη′)=(8.92±0.84±0.65)×10−5 and B(χc2→ηη′)=(2.27±0.43±0.25)×10−5, where the first uncertainties are statistical and the second are systematic. The precision for the measurement of Bc0η′η′) is significantly improved compared to previous measurements. Based on the measured branching fractions, the role played by the doubly and singly Okubo-Zweig-Iizuka disconnected transition amplitudes for χc0,2 decays into pseudoscalar meson pairs can be clarified.

National Category
Astronomy, Astrophysics and Cosmology Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-339781 (URN)10.1103/PhysRevD.96.112006 (DOI)000418202000001 ()
Funder
German Research Foundation (DFG), CRC 1044; FOR 2359Swedish Research Council
Available from: 2018-02-16 Created: 2018-02-16 Last updated: 2018-02-16Bibliographically approved
Ablikim, M., Achasov, M. N., Ahmed, S., Albrecht, M., Amoroso, A., An, F. F., . . . Zou, J. H. (2017). Study of J/ψ and ψ(3686) decays to π+π−η′. Physical Review D: covering particles, fields, gravitation, and cosmology, 96(11), Article ID 112012.
Open this publication in new window or tab >>Study of J/ψ and ψ(3686) decays to π+πη′
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2017 (English)In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 96, no 11, article id 112012Article in journal (Refereed) Published
Abstract [en]

Using the data samples of 1.31×109  J/ψ events and 4.48×108  ψ(3686) events collected with the BESIII detector, partial wave analyses on the decays J/ψ and ψ(3686)→π+π−η′ are performed with a relativistic covariant tensor amplitude approach. The dominant contribution is found to be J/ψ and ψ(3686) decays to ρη′. In the J/ψ decay, the branching fraction B(J/ψ→ρη′) is determined to be (7.90±0.19(stat)±0.49(sys))×10−5. Two solutions are found in the ψ(3686) decay, and the corresponding branching fraction B(ψ(3686)→ρη′) is (1.02±0.11(stat)±0.24(sys))×10−5 for the case of destructive interference, and (5.69±1.28(stat)±2.36(sys))×10−6 for constructive interference. As a consequence, the ratios of branching fractions between ψ(3686) and J/ψ decays to ρη′ are calculated to be (12.9±1.4(stat)±3.1(sys))% and (7.2±1.6(stat)±3.0(sys))%, respectively. We also determine the inclusive branching fractions of J/ψ and ψ(3686) decays to π+π−η′ to be (1.36±0.02(stat)±0.08(sys))×10−4 and (1.51±0.14(stat)±0.23(sys))×10−5, respectively

National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-339762 (URN)10.1103/PhysRevD.96.112012 (DOI)000418917900002 ()
Funder
German Research Foundation (DFG)Swedish Research Council
Available from: 2018-02-02 Created: 2018-02-02 Last updated: 2018-02-02Bibliographically approved
Anastasi, A., Babusci, D., Bencivenni, G., Berlowski, M., Bloise, C., Bossi, F., . . . Wolke, M. (2016). Limit on the production of a new vector boson in e+e− → Uγ, U → π+π− with the KLOE experiment. Physics Letters B, 757, 356-361
Open this publication in new window or tab >>Limit on the production of a new vector boson in e+e− → Uγ, U → π+π− with the KLOE experiment
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2016 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 757, p. 356-361Article in journal (Refereed) Published
Abstract [en]

Abstract The recent interest in a light gauge boson in the framework of an extra U(1) symmetry motivates searches in the mass range below 1 GeV. We present a search for such a particle, the dark photon, in e + e − → U γ , U → π + π − based on 28 million e + e − → π + π − γ events collected at DAΦNE by the KLOE experiment. The π + π − production by initial-state radiation compensates for a loss of sensitivity of previous KLOE U → e + e − , μ + μ − searches due to the small branching ratios in the ρ – ω resonance region. We found no evidence for a signal and set a limit at 90% CL on the mixing strength between the photon and the dark photon, ε 2 , in the U mass range between 527 and 987 MeV . Above 700 MeV this new limit is more stringent than previous ones.

Keywords
Dark matter, Dark forces, Dark photon, U boson
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-289366 (URN)10.1016/j.physletb.2016.04.019 (DOI)000376800300048 ()
Funder
EU, European Research Council, RII3-CT-2004-506078EU, FP7, Seventh Framework Programme, 227431 FP7-INFRASTRUCTURES-2008-1
Available from: 2016-04-29 Created: 2016-04-29 Last updated: 2017-11-30Bibliographically approved
Anastasi, A., Caldeira Balkeståh, L., Cao, B., Heijkenskjöld, L., Ikegami Andersson, W., Johansson, T., . . . Wolke, M. (2016). Measurement of the ϕ→π0e+e− transition form factor with the KLOE detector. Physics Letters B, 757, 362-367
Open this publication in new window or tab >>Measurement of the ϕ→π0e+e− transition form factor with the KLOE detector
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2016 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 757, p. 362-367Article in journal (Refereed) Published
Abstract [en]

A measurement of the vector to pseudoscalar conversion decay ϕ→π0e+e− with the KLOE experiment is presented. A sample of ∼9500 signal events was selected from a data set of 1.7 fb−1 of e+e− collisions at s√∼mϕ collected at the DAΦNE e+e− collider. These events were used to obtain the first measurement of the transition form factor |Fϕπ0(q2)| and a new measurement of the branching ratio of the decay: BR(ϕ→π0e+e−)=(1.35±0.05+0.05−0.10)×10−5. The result improves significantly on previous measurements and is in agreement with theoretical predictions.

Keywords
e(+)e(-) collisions; Conversion decay; Transition form factor
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-289057 (URN)10.1016/j.physletb.2016.04.015 (DOI)000376800300049 ()
Funder
EU, European Research Council, RII3-CT-2004-506078EU, FP7, Seventh Framework Programme, FP7-INFRASTRUCTURES-2008-1 227431
Available from: 2016-04-28 Created: 2016-04-28 Last updated: 2017-11-30Bibliographically approved
Anastasi, A., Babusci, D., Bencivenni, G., Berlowski, M., Bloise, C., Bossi, F., . . . Wolke, M. (2016). Precision measurement of the η → π + π − π 0 Dalitz plot distribution with the KLOE detector. Journal of High Energy Physics (JHEP) (5), Article ID 019.
Open this publication in new window or tab >>Precision measurement of the η → π + π − π 0 Dalitz plot distribution with the KLOE detector
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2016 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 5, article id 019Article in journal (Refereed) Published
Abstract [en]

Using 1.6 fb−1 of e + e − → ϕ → ηγ data collected with the KLOE detector at DAΦNE, the Dalitz plot distribution for the η → π + π − π 0 decay is studied with the world’s largest sample of ∼ 4.7 · 106 events. The Dalitz plot density is parametrized as a polynomial expansion up to cubic terms in the normalized dimensionless variables X and Y . The experiment is sensitive to all charge conjugation conserving terms of the expansion, including a gX 2 Y term. The statistical uncertainty of all parameters is improved by a factor two with respect to earlier measurements.

Keywords
e plus -e- Experiments; QCD
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-292944 (URN)10.1007/JHEP05(2016)019 (DOI)000375714100001 ()
Funder
EU, European Research Council, RII3-CT- 2004-506078EU, European Research Council, 227431
Available from: 2016-05-10 Created: 2016-05-10 Last updated: 2017-11-30Bibliographically approved
Tiemens, M., Caldeira Balkeståhl, L., Calén, H., Fransson, K., Johansson, T., Kupsc, A., . . . Zmeskal, J. (2015). A Triggerless readout system for the bar PANDA electromagnetic calorimeter. Paper presented at 16th Int. Conf. on Calorimetry in High Energy Physics (CALOR 2014), Giessen Germany, 6-11 April, 2014. Journal of Physics, Conference Series, 587(1), Article ID 012025.
Open this publication in new window or tab >>A Triggerless readout system for the bar PANDA electromagnetic calorimeter
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2015 (English)In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 587, no 1, article id 012025Article in journal (Refereed) Published
Abstract [en]

One of the physics goals of the future bar PANDA experiment at FAIR is to research newly discovered exotic states. Because the detector response created by these particles is very similar to the background channels, a new type of data readout had to be developed, called 'triggerless' readout. In this concept, each detector subsystem preprocesses the signal, so that in a later stage, high-level phyiscs constraints can be applied to select events of interest. A dedicated clock source using a protocol called SODANET over optical fibers ensures proper synchronisation between the components. For this new type of readout, a new way of simulating the detector response also needed to be developed, taking into account the effects of pile-up caused by the 20 MHz interaction rate.

National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-287335 (URN)10.1088/1742-6596/587/1/012025 (DOI)
Conference
16th Int. Conf. on Calorimetry in High Energy Physics (CALOR 2014), Giessen Germany, 6-11 April, 2014
Note

PANDA Collaboration, for complete list of authors see http://dx.doi.org/10.1140/epja/i2015-15107-y

Available from: 2016-04-22 Created: 2016-04-22 Last updated: 2017-11-30
Singh, B. P., Erni, W., Keshelashvili, I., Krusche, B., Steinacher, M., Liu, B., . . . Semenov-Tian-Shansky, K. (2015). Experimental access to Transition Distribution Amplitudes with the PANDA experiment at FAIR. European Physical Journal A, 51(8), Article ID 107.
Open this publication in new window or tab >>Experimental access to Transition Distribution Amplitudes with the PANDA experiment at FAIR