L. Heijkenskjöld
A5002105097- Quantum Chromodynamics and Particle Interactions
- Particle physics theoretical and experimental studies
- Nuclear physics research studies
- High-Energy Particle Collisions Research
- Dark Matter and Cosmic Phenomena
- Quantum, superfluid, helium dynamics
- Atomic and Subatomic Physics Research
- Black Holes and Theoretical Physics
- Advanced NMR Techniques and Applications
- Noncommutative and Quantum Gravity Theories
- Cold Fusion and Nuclear Reactions
- Computational Physics and Python Applications
- Research Data Management Practices
- Atomic and Molecular Physics
- Data Quality and Management
- Gamma-ray bursts and supernovae
- Scientific Computing and Data Management
- Machine Learning and Data Classification
- International Science and Diplomacy
- Cosmology and Gravitation Theories
- Astronomical and nuclear sciences
University of Basel
2023
Johannes Gutenberg University Mainz
2018-2022
Uppsala University
2011-2020
Forschungszentrum Jülich
2014-2020
Saint Mary's University
2018
University of Giessen
2016-2017
Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati
2015-2016
Istituto Nazionale di Fisica Nucleare, Sezione di Bari
2016
University of Bari Aldo Moro
2013-2014
Exclusive and kinematically complete high-statistics measurements of quasifree polarized $\stackrel{\ensuremath{\rightarrow}}{n}p$ scattering have been performed in the energy region narrow resonancelike structure ${d}^{*}$ with $I({J}^{P})=0({3}^{+})$, $M\ensuremath{\approx}2380\text{ }\text{ }\mathrm{MeV}$, $\mathrm{\ensuremath{\Gamma}}\ensuremath{\approx}70\text{ }\mathrm{MeV}$ observed recently double-pionic fusion channels...
The existence of a new force beyond the Standard Model is compelling because it could explain several striking astrophysical observations which fail standard interpretations. We searched for light vector mediator this dark force, $\mathrm{U}$ boson, with KLOE detector at DA$\Phi$NE $\mathrm{e}^{+}\mathrm{e}^{-}$ collider. Using an integrated luminosity 1.54 fb$^{-1}$, we studied process $\mathrm{e}^{+}\mathrm{e}^{-} \to \mathrm{U}\gamma$, $\mathrm{U} \mathrm{e}^{+}\mathrm{e}^{-}$, using...
We have searched for a light vector boson U, the possible carrier of "dark force", with KLOE detector at DAΦNE e+e− collider, motivated by astrophysical evidence presence dark matter in Universe. Using collisions collected an integrated luminosity 239.3 pb−1, we look dimuon mass peak reaction e+e−→μ+μ−γ, corresponding to decay U→μ+μ−. find no U signal. set 90% CL upper limit mixing parameter squared between photon and 1.6×10−5 8.6×10−7 region 520<mU<980 MeV.
The recent interest in a light gauge boson the framework of an extra U(1) symmetry motivates searches mass range below 1 GeV. We present search for such particle, dark photon, e+e−→Uγ, U→π+π− based on 28 million e+e−→π+π−γ events collected at DAΦNE by KLOE experiment. π+ π− production initial-state radiation compensates loss sensitivity previous U→e+e−, μ+μ− due to small branching ratios ρ–ω resonance region. found no evidence signal and set limit 90% CL mixing strength between photon ε2, U...
Neutral kaon pairs produced in phi decays anti-symmetric entangled state can be exploited to search for violation of CPT symmetry and Lorentz invariance. We present an analysis the CP-violating process phi->K_S K_L->pi+pi-pi+pi- based on 1.7 fb-1 data collected by KLOE experiment at Frascati phi-factory DAFNE. The are used perform a measurement CPT-violating parameters Delta_amu neutral kaons contest Standard Model Extension framework. measured reference frame fixed stars are: Delta_ao =...
Exclusive measurements of the quasifree $pn\ensuremath{\rightarrow}pp{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{\ensuremath{-}}$ reaction have been performed by means $pd$ collisions at ${T}_{p}$ $=$ 1.2 GeV using wide angle shower apparatus (WASA) detector setup cooler synchrotron COSY (Institut f\"ur Kernphysik, J\"ulich). Total and differential cross sections obtained covering energy region $\sqrt{s}$ (2.35--2.46) GeV, which includes ABC effect its associated resonance structure. No...
New data on quasifree polarized neutron-proton scattering in the region of recently observed ${d}^{*}$ resonance structure are obtained by exclusive and kinematically complete high-statistics measurements with WASA at COSY. This paper details determination beam polarization, checks character process, all ${A}_{y}$ angular distributions new partial-wave analysis, which includes producing a pole ${}^{3}{D}_{3}\ensuremath{-}{}^{3}{G}_{3}$ coupled partial waves...
Exclusive measurements of the quasi-free $np \to np\pi^0\pi^0$ reaction have been performed by means $dp$ collisions at $T_d$ = 2.27 GeV using WASA detector setup COSY. Total and differential cross sections obtained covering energy region $\sqrt s$ (2.35 - 2.46) GeV, which includes ABC effect its associated $d^*(2380)$ resonance. Adding $d^*$ resonance amplitude to that for conventional processes leads a reasonable description data. The observed in total section is agreement with predictions...
Using 1.6 fb−1 of e + − → ϕ ηγ data collected with the KLOE detector at DAΦNE, Dalitz plot distribution for η π 0 decay is studied world's largest sample ∼ 4.7 · 106 events. The density parametrized as a polynomial expansion up to cubic terms in normalized dimensionless variables X and Y . experiment sensitive all charge conjugation conserving expansion, including gX 2 term. statistical uncertainty parameters improved by factor two respect earlier measurements.
We report on a high-statistics measurement of the most basic double pionic fusion reaction $\vec{n}p \to d\pi^0\pi^0$ over energy region $d^*(2380)$ resonance by use polarized deuteron beam and observing in quasifree scattering mode. The measurements were performed with WASA detector setup at COSY. data reveal substantial analyzing powers confirm conclusions about $d^*$ obtained from unpolarized measurements. also previous under complementary kinematic conditions.
A measurement of the vector to pseudoscalar conversion decay $\phi \to \pi^0 e^+e^-$ with KLOE experiment is presented. sample $\sim 9500$ signal events was selected from a data set 1.7 fb$^{-1}$ $e^+e^-$ collisions at $\sqrt{s} \sim m_{\phi}$ collected DA$\Phi$NE collider. These were used obtain first transition form factor $| F_{\phi \pi^0}(q^2) |$ and new branching ratio decay: $\rm{BR}\,(\phi e^+e^-) = (\,1.35 \pm 0.05^{\,\,+0.05}_{\,\,-0.10}\,) \times 10 ^{-5}$. The result improves...
We have studied the vector to pseudoscalar conversion decay ϕ→ηe+e−, with η→π0π0π0, KLOE detector at DAΦNE. The data set of 1.7 fb−1 e+e− collisions s∼Mϕ contains a clear signal ∼31,000 events from which we measured value BR(ϕ→ηe+e−)=(1.075±0.007±0.038)×10−4. same sample is used determine transition form factor by fit invariant mass spectrum, obtaining bϕη=(1.28±0.10−0.08+0.09) GeV−2, that improves five precision previous measurement and in good agreement VMD expectations.
We searched for evidence of a Higgsstrahlung process in secluded sector, leading to final state with dark photon U and Higgs boson h', the KLOE detector at DAFNE. investigated case h' lighter than U, decaying into muon pair producing missing energy signature. found no set upper limits its parameters range 2m_mu<m_U<1000 MeV, m_h'<m_U.
Exclusive and kinematically complete measurements of the double pionic fusion to ${}^{3}\mathrm{He}$ have been performed in energy region so-called ABC effect, which denotes a pronounced low-mass enhancement $\ensuremath{\pi}\ensuremath{\pi}$-invariant mass spectrum. The experiments were carried out with WASA detector setup at COSY (the cooler synchrotron Forschungszentrum J\"ulich). Similar observations basic $pn\ensuremath{\rightarrow}d{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}$ reaction...
The absolute branching ratio of the K+→π+π−π+(γ) decay, inclusive final-state radiation, has been measured using ∼17 million tagged K+ mesons collected with KLOE detector at DAΦNE, Frascati ϕ-factory. result is:BR(K+→π+π−π+(γ))=0.05565±0.00031stat±0.00025syst a factor ≃ 5 more precise respect to previous result. This work completes program precision measurements dominant kaon ratios KLOE.
We have carried out a new direct search for the CP violating decay KS -> 3pi0 with 1.7 fb^-1 of e+e- collisions collected by KLOE detector at phi-factory DAFNE. searched this in sample about 5.9 x 10^8 KL events tagging means interaction calorimeter and requiring six prompt photons. With respect to our previous search, analysis has been improved increasing factor four tagged more effective background rejection fake tags spurious clusters. find no candidates data simulated samples, while...
We have measured the running of effective QED coupling constant $\alpha(s)$ in time-like region $0.6<\sqrt s< 0.975$ GeV with KLOE detector at DA$\Phi$NE using Initial State Radiation process $e^+e^-\to\mu^+ \mu^-\gamma$. It represents first measurement this energy region. Our results show a more than 5$\sigma$ significance hadronic contribution to $\alpha(s)$, which is strongest direct evidence both time- and space-like regions achieved single measurement. By $e^+e^-\to\pi^+\pi^-$ cross...
Exclusive measurements of the quasi-free pn→ppπ− and pp→ppπ0 reactions have been performed by means pd collisions at Tp=1.2 GeV using WASA detector setup COSY. Total differential cross sections obtained covering energy region Tp=0.95–1.3GeV (s=2.3–2.46 GeV), which includes regions Δ(1232), ⁎N⁎(1440) ⁎d⁎(2380) resonance excitations. From these isoscalar single-pion production has extracted, for data existed so far only below Tp=1 GeV. We observe a substantial increase this section around 1...
A precise measurement of the differential cross sections dσ/dΩ and linearly polarized photon beam asymmetry Σ_{3} for Compton scattering on proton below pion threshold has been performed with a tagged almost 4π detector at Mainz Microtron. The incident photons were produced by recently upgraded Glasgow-Mainz tagging facility impinged cryogenic liquid hydrogen target, scattered detected in Crystal Ball/TAPS setup. Using highest statistics data ever measured along two effective field theories...
Exclusive and kinematically complete high-statistics measurements of the double pionic fusion reaction $dd \to ^4$He$\pi^0\pi^0$ have been performed in energy range 0.8 - 1.4 GeV covering thus region ABC effect, which denotes a pronounced low-mass enhancement $\pi\pi$-invariant mass spectrum. The experiments were carried out with WASA detector setup at COSY. Similar to observation basic $pn d \pi^0\pi^0$ reaction, data reveal correlation between effect resonance-like dependence total cross...
The $\ensuremath{\gamma}n\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}n$ differential cross section evaluated for 27 energy bins span the photon-energy range 290--813 MeV ($W=1.195$--1.553 GeV) and pion c.m. polar production angles, ranging from ${18}^{\ensuremath{\circ}}$ to ${162}^{\ensuremath{\circ}}$, making use of model-dependent nuclear corrections extract ${\ensuremath{\pi}}^{0}$ data on neutron measurements deuteron target. Additionally, total photoabsorption was measured. tagged...