UNIVERSITY of TURIN and INFN Department of Physics Antiproton production cross sections in cosmic rays Michael Korsmeier 13-Nov-19 XSCRC 2019 - CERN !1 Michel Korsmeier Outline • Motivation to study antiprotons in cosmic rays • Parameterizing the secondary antiproton production cross section Based on: Korsmeier, Donato, di Mauro; Phys.Rev. D97 (2018) no.10, 103019 • Requirements for future cross section measurements Based on: Donato, Korsmeier, di Mauro; Phys. Rev. D96 (2017) 043007 University of Turin Michael Korsmeier !2 Introduction CR propagation →! Talk by Yoann →! Talk by Mathieu →! Talk by Marco University of Turin Michael Korsmeier !3 Introduction CR propagation University of Turin Michael Korsmeier !4 Contribution of various CR+ISM channels ∞ dσCR+ISM→p¯ ! qCR+ISM→p¯(Tp¯) = dT4πnISMΦCR(T) (T, Tp¯) ∫ dTp¯ 0 Dominant antiproton production channels in CRs: • pp channel (50% - 60%) • pHe channel (15% - 20%) • Hep channel (10% - 20%) • HeHe channel few percent • CNO + ISM few percent [ MK, Donato,Di Mauro; 2018] [ MK, Donato,Di Mauro; • … Channels with secondary CRs or heavy ISM can slightly change the energy behavior, but these channels are suppressed below the percent level. University of Turin Michael Korsmeier !5 Uncertainties in p!¯ cross sections dσ d3σ ! (T , T ) = p dΩ E (T , T , θ) p p¯ p¯ 3 p p¯ dTp¯ ∫ ( dp ) [Donato, MK, Di Mauro; 2017] [Donato, MK, Di Mauro; There are large di"erences between various cross section parametrizations used to predict CR antiprotons. University of Turin Michael Korsmeier !6 Antineutrons and antihyperons Ep [GeV]Isospin asymmetry Antihyperons 101 102 103 104 105 106 107 108 0.5 Ep [GeV] Ep [GeV] 101 102 103 104 105 106 107 108 102 103 104 105 106 107 0.5 0.4 BHM NA49 pC 0.8 0.4 NAL 0.3 Na49 np NA49 pC MIRABELLE 0.6 IS 0.3 Fermilab NA49 0.2 Na49 np p 30 in / IS - STAR Fermilab 0.2 0.1 0.4 ISR ALICE STAR 0.1 STAR 0.0 ALICE 0.2 ALICE 1 0.0 2 3 4 CMS 10 10 10 10 [Winkler; 2017] 0.0 s [10GeV1 ] 102 103 104 101 102 103 104 s [GeV] s [GeV] Galaxy prompt Antineutrons 3 3 d σ d σ Isospin asymmetry ! E = E ⋅ (2 + ΔIS + 2ΔΛ) ( dp3 ) ( dp3 ) Antihyperons pp→p¯ pp→p¯ University of Turin Michael Korsmeier !7 Part I Parameterizing the secondary antiproton # production cross section University of Turin Michael Korsmeier !8 Roadmap to update the recent XS parametrizations • We update the two most recent analytic cross section parametrizations Param. I: [Di Mauro+, 2014] Param. II: [Winkler, 2017] using data from NA61 and LHCb • We use for the first time the data in the pHe channel • We derive uncertainties from cross sections on the CR source term University of Turin Michael Korsmeier !9 Reanalysis of the cross section parametrizationsFit strategy and important data sets • Fit of two most recent (analytic) parametrizations for antiproton production in pp collisions !2-fit of the pp parametrization • Fit of pA parametrization by to pp data Experiment CM-energy [GeV] Channel rescaling from pp NA49 17.3 pp NA61 7.7, 8.8, 12.3, 17.3 pp Fix the pp Dekkers 6.1, 6.7 pp Experiment CM-Energy [GeV] Channel parameters NA49 17.3 pp LHCb 110 pHe NA61 7.7, 8.8, 12.3, 17.3 pp !2-fit of the pA NA49 17.3 pC Dekkers 6.1, 6.7 pp rescaling factor to pA data LHCb 110 pHe NA49 17.3 pC 12-Nov-19 Michael Korsmeier University of Turin 6 Michael Korsmeier !10 Fractional source term contribution NA61 covers a large range and a high fraction of the antiproton source term in the pp channel. On the other hand, the contribution of LHCb in the pHe and Hep channel is almost negligible. University of Turin Michael Korsmeier !11 Cross section parametrization Param I (di Mauro): d3σ C4 C7 ! C1 2 E ( s, xR, pT) = σin(1 − xR) exp(−C2xR) C3 s exp(−C5pT) + C6 s exp (−C8pT) ( dp3 ) [ ( ) ( ) ] pp 8 free parameters in the fit! Param. II (Winkler): − 1 d3σ X C3X ! C2 E ( s, xR, pT) = σinR( s, xR, pT) C1(1 − xR) 1 + (mT − mp) ( dp3 ) [ GeV ] pp 1 , s10 GeV s ! 5 2 and ! 2 R = s s X = C4 log 1 + C5 10 − exp C6 10 − (xR − xR,min) , elsewhere ( 4mp ) [ ( GeV ) ] [ ( GeV ) ] 5 free parameters in the fit! Both parametizations exploit the scaling invariance of the antiproton production cross section in ! for CM energies between ~10 GeV to 50 GeV. xR = Ep*¯ /Ep*¯,max University of Turin Michael Korsmeier !12 Result in the pp channel dσ d3σ ! (T , T ) = p dΩ E (T , T , θ) p p¯ p¯ 3 p p¯ dTp¯ ∫ ( dp ) Energy-di"erential cross section • Both parametrizations provide a good fit to the available data • The results are compatible within uncertainties • MC generators like EPOS- [ MK, Donato,Di Mauro; 2018] [ MK, Donato,Di Mauro; LHC and QGSJET (KMO) overpredict p%¯ at low Param. I: [Di Mauro+, 2014]$ energies Param. II: [Winkler, 2017]$ University of Turin Michael Korsmeier !13 The secondary antiproton source term ∞ dσpp→p¯ ! qpp→p¯(Tp¯) = dTp4πnISM,pΦp(Tp) (Tp, Tp¯) ∫ dTp¯ 0 pp channel: prompt production • The uncertainty of the secondary source term of p%¯ imposed by cross section is 8% to 15%$ At % the • Tp¯ > 5 GeV uncertainty is mostly a normalisation while at lower energies also the shape is uncertain [ MK, Donato,Di Mauro; 2018] [ MK, Donato,Di Mauro; University of Turin Michael Korsmeier !14 The proton nucleus channels • Data in the proton nucleus channel is scarce and a standalone parametrization is not possible $ • We assume that pA channels are proportional to pp We allow for an % dependence to incorporate forward- • xf backward asymmetry pA pp d3σ d3σ ! pA E ( s, xf, pT) = f (A, xf, �) E ( s, xf, pT) ( dp3 ) ( dp3 ) N ! pA D1 D2 f (A, xf ) = A A 1 + ΔIS Ftar(xf ) + Fpro(xf ) [ ( A ) ] University of Turin Michael Korsmeier !15 The impact of LCHb data Param. I: [Di Mauro+, 2014] Param. II: [Winkler, 2017] [ MK, Donato,Di Mauro; 2018] [ MK, Donato,Di Mauro; Param. II provides a much better fit to the LHCb data. University of Turin Michael Korsmeier !16 Source terms in the proton nucleus channels pHe channel: prompt production Hep channel: prompt production [ MK, Donato,Di Mauro; 2018] [ MK, Donato,Di Mauro; University of Turin Michael Korsmeier !17 Total secondary antiproton source term Cross section uncertainties are up to 20% at low energies. [ MK, Donato,Di Mauro; 2018] [ MK, Donato,Di Mauro; Isospin and hyperons Prompt antiprotons ratio University of Turin Michael Korsmeier !18 Part II Requirements for future cross section measurements University of Turin Michael Korsmeier !19 Precision of AMS-02 flux measurements Relative uncertainty of the AMS-02 antiproton flux What is the required parameter space and precision for cross section measurements? Our guiding principles: • The uncertainty of cross section in the prediction of the antiproton flux shall match (not exceed) AMS-02 accuracy • Cross sections have to be measured more precisely where their contribution to the source term is large University of Turin Michael Korsmeier !20 Guidance for future XS measurements Fix target experiment Collider experiment d3σ d3σ ! ! E Tp, Tp¯, η E ( s, xR, pT) ( dp3 ) ( ) ( dp3 ) [Donato, MK, Di Mauro; 2017] [Donato, MK, Di Mauro; If the source term is measured with 3% accuracy inside the blue contours and with 30% outside the contours we can reach the measurement uncertainties of the AMS-02 antiproton flux. University of Turin Michael Korsmeier !21 Prospects of COMPASS++/AMBER pHe channel Hep channel The COMPASS++/AMBER collaboration has the potential to significantly improve cross section measurements in the pHe channel. →! Talk by Paolo on Friday University of Turin Michael Korsmeier !22 Conclusion • Antiproton production cross sections are an important ingredient to understand the recent and precise flux measurements by AMS-02 • Uncertainties of cross sections in prediction of the antiproton source term are between 12% and 20% • Future cross section measurements can improve our understanding of antiproton production in cosmic rays Thank you for your attention! University of Turin Michael Korsmeier !23 Introduction CR propagation Backup University of Turin Michael Korsmeier !24 Precision of current XS measurements University of Turin Michael Korsmeier !25 Guidance for future XS measurements University of Turin Michael Korsmeier !26 Precision analyses with CR antiprotons 1.1% σ excess is not significant Significance at 2.9% σ [Cuoco, MK, +; 2019] [Reinert, Winkler; 2018] 3.3% σ to 4.7% σ: robust excess Antiprotons are consistent with secondary origin [Cholis, Linden, Hooper; 2019] [Boudaud, Genolini, +; 2019] →! Talk by Mathieu University of Turin Michael Korsmeier !27.