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The PADME experiment at LNF

The PADME experiment at LNF. Stan dard Model SU(3) ×SU(2)×U(1). Dark Sector ??????. Vector “portal”. More details on the proposal can be found in: White Paper della CSN I: Frascati Phys. Ser. 60 (2015) 1-302

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The PADME experiment at LNF

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  1. The PADME experiment at LNF Standard Model SU(3) ×SU(2)×U(1) Dark Sector ?????? Vector “portal” • More details on the proposal can be found in: • White Paper della CSN I: Frascati Phys. Ser. 60 (2015) 1-302 • “Proposal to search for the Dark Photon in positron on target collision at DAFNE LINAC” • Adv. High Energy Phys. 2014 959802 • Kick-off meeting di PADME: http://agenda.infn.it/event/padme-kickoff • PADME website: http://www.lnf.infn.it/acceleratori/padme/index.html M. Raggi, Challenges in the Dark Sector: Alternatives to the WIMP paradigm

  2. A’ production and decays • A’ boson can be produced in e+collision on target by: • Bremsstrahlung: e+N →e+NA’ • Annihilation: e+e-→ gA’ • Meson decays • If no dark matter candidate lighter than the A’boson exists: • A’→e+e-, m+m-, p+p-. • These are the so called “visible” decays • For MA’<210 MeV A’ only decays to e+e- with BR(e+e-)=1 • If any dark matter particle c with 2Mc<MA’exists • A’ will dominantly decay into pure DMand BR(l+l-) becomes small ~ e2 • A'→cc ~ 1. These are the so called decays to “invisible” particles Bremsstrahlung Annihilation Meson decays M. Raggi, Challenges in the Dark Sector: Alternatives to the WIMP paradigm

  3. Visible decays status am e ae limits + g A’ e - La bandafavorita da (g-2)mèpraticamentetuttaesclusa, nell’ipotesicheil dark photon non possadecadere in particelle del settoreoscuro Sarebbecomunqueimportante un esperimentodedicatoallaricerca del dark photon nellaregione mA’<100 MeV beam-dump experiments M. Raggi, Challenges in the Dark Sector: Alternatives to the WIMP paradigm

  4. “Invisible decays” status Invece lo spaziodeiparametriesclusoammettendocheil dark photon possadecadere in particelle del settoreoscuro(Mc<MA’/2)è molto ridotto Èanchepossibile re-interpretareesperimenti di dumpin termini di scattering di particelle di dark matterprovenientidaidecadimentiinvisibiliA’ cc Lo spazio da esplorarepassa da 2 a 4 parametri L’esclusionedipendeinfattidallacostante di accoppiamentoaDe dallamassadelleparticelle del settoreoscuromc aD aD e e M. Raggi, Challenges in the Dark Sector: Alternatives to the WIMP paradigm

  5. Dark photon activity @ KLOE 2012 KLOE experiment φ → ηA′ A′ → e+e− e+e− → A′γ, A′ → e+e− 2013 2015 e+e− → A′γ A′ → μ+μ− M. Raggi, Challenges in the Dark Sector: Alternatives to the WIMP paradigm

  6. The PADME approach to A’ searches • At present all experimental results rely on at least one of the following model-dependent assumptions: • A’ decays to e+e-(visible decays assumption) and thus BR(A’→e+e-)= 1 • A’ couples with the same strength to all fermions (eq= el) (kinetic mixing) • In the most general scenario: • A’ can decay to dark sector particles cwith mc<MA’/2⇒BR(A’→e+e- <<1) Dump and meson decay experiment results suppressed by e2 • A’ can couple to quark with a coupling constant smaller el or even 0 Suppressed or no production at hadronic machines and in mesonsdecays • PADME aims at detecting A’ produced in e+e- annihilation and decaying into any final state by searching for missing mass in e+e-→gA’, A’→ccprocess • No assumption on the A’ decays products and coupling to quarks • Only minimal assumption: A’ couples to leptons • PADME will limit the coupling of any new light particle produced in e+e- collisions: scalars (Hd),vectors (A’ and Zd) M. Raggi, Challenges in the Dark Sector: Alternatives to the WIMP paradigm

  7. The PADME experiment • Beam: 103-104 e+ on target per bunch, at 50 bunch/s (1013-1014 e+/year) • Main detector components: • Active target, thin: 50-100mm diamond (Time, Ne-, beam position and spot size) • Magnetic spectrometer or scintillating veto ~1m length • Conventional magnet, B≈0.6T but large gap for gaining acceptance • Cylindrical crystal (BGO or LYSO) EM calorimeter R=15 cm (with 1x1x20 cm3crystals) • Measures: time, energy and direction of photons • Compute the Mmiss2 = (P4e- + P4beam - P4g)2 • P4e- =(0,0,0,me) and P4beam =(0,0,550,sqrt(5502 + me2)) 1.75 m M. Raggi, Challenges in the Dark Sector: Alternatives to the WIMP paradigm

  8. PADME experiment at BTF Nello splitting previstodellelinee BTF PADME dovrebbeoccupare la salaoggiadibitaai test beam L’accesso al detector in parte ristretto a causadellapresenza di un’altralinea di fascio in sala. Come mostrato dal Layout sipuo’ alloggiare PADME anchenellaversione 4m. M. Raggi, Challenges in the Dark Sector: Alternatives to the WIMP paradigm

  9. PADME experiment layout Il layout attuale ha unadistanza di 200 cm traEcal e target. Un angolo di accettanza di ± 4.3 gradi. Non e’ ancorachiaroquantosial’ingombro del magnetenella zone dei coil da verificare con ilmagneteappenaarriva. Regionedellatarghetta da definiresia in posizioneche in geometria. (Dentro o fuoridai coil?) M. Raggi, Challenges in the Dark Sector: Alternatives to the WIMP paradigm

  10. Schema di PADME invisible Positron Veto Scintillatori 1 cm, letturaSiPM Dipole MBP-S (transfer line SPS) Parte superiore non mostrata “small angle” VetoBaF2o cristalloveloce Vuoto g Active Target 50-100 mm di diamante segmentato Calorimeter Cristalli di BGO 1×1cm2 A’ Fascio di positroni Electron Veto Scintillatori 1 cm, letturaSiPM M. Raggi, Challenges in the Dark Sector: Alternatives to the WIMP paradigm

  11. Monte Carlo M. Raggi, Challenges in the Dark Sector: Alternatives to the WIMP paradigm

  12. Main Backgrounds Backgrounds g e- g g e- e+ g e+ g g e+ +1 electron +1 g +2 g g e+ M. Raggi, Challenges in the Dark Sector: Alternatives to the WIMP paradigm

  13. PADME sensitivity to invisible decays 1013eot= 6000 e+/40 ns × 3.1107 s × 49 Hz PADME can probe the da (g-2)mup to M2A’= 2meEe+ Ee+=550 MeV: MA’ < 23.7 MeV/c2 Ee+=750 MeV: MA’ < 27.7 MeV/c2 Ee+=1 GeV: MA’ < 32 MeV/c2 M. Raggi, Challenges in the Dark Sector: Alternatives to the WIMP paradigm

  14. Tentative time schedule Project has been financed on the “What Next” INFN program starting for 2016. The colaboration is still small LNF, RM1, LECCE, Sofia University M. Raggi, Challenges in the Dark Sector: Alternatives to the WIMP paradigm

  15. More physics cases at PADME • PADME is a general propose experiment searching for the process: • e+e- -> g + missing mass • Preliminary sensitivity studies used as benchmark the dark photon + kinetic mixing minimal model • There are possibilities to study other physics cases • ALP searches with ggor “invisible” final states • Dark Higgs searches in multi leptons final states (6 electrons) • … and hopefully more to come from you M. Raggi, Challenges in the Dark Sector: Alternatives to the WIMP paradigm

  16. PADME and Axion Like Particles (ALP) ALP production @ PADME + PADME can perform a direct search for this process and measure both di gaggand mafor 3 gor 1 g + M2miss Is there any other production mechanism? ALP-strahlung in case of coupling to fermions. What is the PADME sensitivity with 1013 EOT? Is there any new information with respect to LEP data? (ArXiv: 1509.00476v1) M. Raggi, Challenges in the Dark Sector: Alternatives to the WIMP paradigm

  17. Search for dark Higghs at PADME? Dark Higgs Production at PADME Depending on the mass hierarchy final state with 2leptons + Miss Energy or 6 leptons could be observed at PADME For Mh’ >2 MA’ h’ -> 2A’ -> 2l++2 l- (6 leptons) For Mh’< 2 MA’ h’ -> Invisible What is the PADME sensitivity with 1013 EOT? Could PADME fill the gap at low masses mh’< 1GeV? M. Raggi, Challenges in the Dark Sector: Alternatives to the WIMP paradigm

  18. PADME dump experiment 1e20 EOT Dark Photon exclusion with a DUMP @ LNF Improving the bunch length and optimizing the positron yield the DAFNE LINAC can provide 1x1020 electron on target per year PADME-dump 1×1020EOT/y preliminary M. Raggi, Challenges in the Dark Sector: Alternatives to the WIMP paradigm

  19. Invisible dump search at LNF? A. Celentanohttp://agenda.infn.it/event/padme-kickoff • Estimate of a BDX like experiment a Frascati • Stima con 1x1020 EOT da 1 GeV in un anno di presadati • Ottimizzazione del detector possible per migliorare la sensitivita’ M. Raggi, Challenges in the Dark Sector: Alternatives to the WIMP paradigm

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