Prospects and challenges for future ee and ep colliders

Prospects and challenges for future ee and ep colliders Marcin Chrzaszcz mchrzasz@cern.ch Physik-Insitut, University of Zurich Instiute of Nuclear Physics, Polish Academy of Sciences Neutrinos at the High Energy Frontier, Amherst, 18-20 July, 2017 1 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 1/43 43

Outline Future e + e colliders. ILC CLIC FCCee,eh Detector Physics program: Higgs program. Z pole program. WW program. t t program. Neutrino program. 2 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 2/43 43

Quo Vadis HEP?... and what is still missing. What has LHC found... Dark matter/energy? Neutrino masses? A Higgs boson. mh = 125 GeV ΓH = 4.1 MeV Matter/antimatter asymmetry? LHC has ongoing physics program... Run 2 +3: 300 by 2023 HL-HLC: 3000 by 2035 But what for post-lhc area? Need to plan now! 3 Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC / 43 3/43

International Linear Collider (ILC) 4 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 4/43 43

International Linear Collider (ILC) The ILC concept was reviewed by the Japanese government. Feedbacks (domestic only) Academia in general: reserved/hostile Funding authorities: reserved/critical Political allies (Local/Central): enthusiastic/cautious Given the fact that the energy scale of new physics is currently unknown, the physics reach of precision Higgs and other SM probes of ILC250 are comparable to that of ILC500, Hiroaki Aihara 5 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 5/43 43

Compact Linear Collider (CLIC) CLIC also wants a staged approach: 6 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 6/43 43

Future Circular Collider (FCC) FCC - study: pp collider: the ultimate goal. ee collider: first step. ep collider: additional option. 98 km infrastructure in Geneva area The Goal: CDR and cost review by the end of 2018! 7 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 7/43 43

8 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 8/43 43

Time line of FCC 9 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 9/43 43

Why circular collider? To achieve interesting physics program one would have to obtain a factor of 10 3 of LEP luminosity. The Luminosity scales: L R P SR β So how can one increase the luminosity without the electric energy cost? The answer is inside the B-factory design! One has to lower the beam emittance: β. 10 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 10/43 43

Why circular collider? To achieve interesting physics program one would have to obtain a factor of 10 3 of LEP luminosity. The Luminosity scales: L R P SR β So how can one increase the luminosity without the electric energy cost? The answer is inside the B-factory design! One has to lower the beam emittance: β. 10 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 10/43 43

β over last 40 years The β will be increased to 1mm compared to 5 cm at LEP. SuperKEKB will pave the way towards β < 1 mm. Additional improvements to reach the 10 3 factor in lumi are: Continues injection More bunches 11 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 11/43 43

Beam parameters Identical beam optics for all energies. FCC would have two separate rings Detectors similar to the ILC and CLIC. 12 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 12/43 43

Comparison of e + e colliders 13 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 13/43 43

FCCep Requires additional ERL Would be needed anyway for FCChh. 14 Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC / 43 14/43

Detectors requirements E.Leogrande 15 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 15/43 43

CLIC detector E.Leogrande 16 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 16/43 43

Tracker E.Leogrande 17 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 17/43 43

IDEA detector M.Dam 18 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 18/43 43

Tracker M.Dam 19 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 19/43 43

Tracker (for) the idea ;) M.Dam 20 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 20/43 43

Physics program 21 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 21/43 43

Higgs production 22 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 22/43 43

Higgs Mass A very clean Higgs mass determination in e + e ZH and using a recoil technique (unique for lepton colliders): m recoil = ( s E µ ) 2 p µ 2 With Z µµ and Z ee ZH decays are tagged independently of the Higgs decay mode. Precise measurement of g HZZ : 23 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 23/43 43

Higgs Width Credit to Mark Thomson Higgs-strahlung. Total HZ crossection: σ(hz) g 2 HZZ Exclusive cross section: σ(hz) Br(H XX) g 2 HZZ g2 HXX Γ H Total Higgs width from WW process: σ(hz) Br(H b b) σ(hνν) Br(H b b) g2 HZZ g 2 HW W And finally: σ(hνν) Br(H WW ) g4 HW W H From this: H. 24 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 24/43 43

Higgs Couplings The Higgs couplings to WW, ZZ, c c, gg, τ τ +, γγ can be determined via tagging the respective Higgs decay final states Observables: Marcin Chrzaszcz Factor (Universität of 10 Zürich) improvementssearch for formost massive neutrinos couplings. 25 / at LHCb and discovery potential of the FCC 25/43 43 σ(e + e ZH) Br(H X) σ(e + e Hνν) Br(H X)

Higgs Production in S-channel Potentially possibility to measure the Hee Yukawa coupling! Several final states can be studied. It requires running: s = MH = 125 GeV Since Γ H = 4.2 MeV, it requires monochromatization (increasing the energy resolution in the CMS energies for e e + interaction without reducing the inherent energy spread of the colliding beams) Limits 3.5 times the SM predictions in both cases. 26 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 26/43 43

Normalized Higgs Couplings Higgs couplings normalized to the SM predictions: k x = g Hxx g SM Hxx 27 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 27/43 43

MegaTop: t t threshold scan For the first time the the top quark to be studied using a precisely defined leptonic state. The dependence of the t quark cross-section shape on the t quark mass and interactions is computable to high precision (depends on m t, Γ t, α s, g H tt, ISR, luminosity spectrum). PRD: m = (173.21 ± 0.51 ± 0.71) FCCee: σ(m t ) < 10 MeV 28 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 28/43 43

Physics program WW Measurement of m W from σ WW Max statistical sensitivity at s = 2mW + 0.6 GeV Stat. precision with L = 11 pb 1 350 MeV with L = 8 ab 1 0.4 MeV Sys. precision needed: E(beam) < 0.4 MeV ϵ/ϵ < 10 4 σ B < 0.7 fb m F W CC = 500 kev m LEP W = 50 MeV 29 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 29/43 43

Physics program at the Z pole L = 3 10 36 4 10 12 Z decays. Z mass and width wit precision of 10 kev (stat) +100 kev (sys). Radiation function calculated to O(α 3 s) 10 4 Relative precisions (JHEP01(2014)164): R l = 5 10 5 Γ l Γ had R b = Γ b b Γ had N ν 10 3 2 5 10 5 rel α s (m 2 Z) 2 10 3 QED α s (m 2 Z) 3 10 3 30 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 30/43 43

Z pole summary From A.Blondel 31 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 31/43 43

Flavour Physics Flavour Physics is an very active topic: LHCb will dominate in the decays where the muon are in final state. However τs are very challenging for them! Overall O(10 3 ) events! Angular analysis possible. Similar beeing studied for B 0 s ττ. 32 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 32/43 43

Right-handed neutrinos Neutrino oscillations: at least two massive light neutrinos. No renormalisable way in the SM therefore evidence for new physics. Sterile neutrinos for type I seesaw mechanism. 33 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 33/43 43

Neutrino mass eigenstates See-saw mechanism: tg 2θ = 2m D M, m R ν = 1 2 [ M R + M = 1 2 L = 1 ( ) ( ) 2 ( ν L, N R) e 0 md v c L m T D M R N R [ M R ] MR 2 + 4m 2 D ] MR 2 + 4m 2 D Dirac only M R = 0, m D 0 4 states of equal masses. I = 1/2 active neutrinos. I = 0 sterile neutrinos. Majorana only M R 0, m D = 0 4 states of equal masses. I = 1/2 active neutrinos. I = 0 sterile neutrinos. Dirac + Majorana M R 0, m D 0 4 states of diff. masses. I = 1/2 active neutrinos. I = 0 ALMOST sterile neutrinos. 34 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 34/43 43

Right handed neutrinos ν = ν L cos θ N c R sin θ N = N R cos θ + ν c L sin θ In the EW interaction the ν L are produced: ν L = ν cos θ + N sin θ ν L - light mass eigenstate N - heavy mass eigenstate ν L - active neutrino N R - sterile neutrino Many consequences: Effect on neutrino oscillations (ev mass) Dark matter (kev mass regime) Z invisible width. Exotic particle decays: HνN and ZνN. Heavy Flavour physics: strange, charm, beauty flavoured mesons via W. Violation on lepton flavour/universality. 35 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 35/43 43

Collider experiments arxiv::1503.05491 B-factories: pp colliders: Z factory: ee colliders: and many many more... 36 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 36/43 43

Production in Z decays A.Blondel Production: Br(Z ν m ν) = Br(Z ν ν) U 2 (1 m2 ν m m 2 Z ) 2 ( 1 + 1 2 m 2 ν m m 2 Z ) Decay length: L 3cm U 2 (m 2 ν) 6 Background: four fermion: e e + W W, e e + Z (νν) + Z/γ Long lifetime of N helps rejecting the background! 37 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 37/43 43

Detection at a hadron collider Super easy to detect topology! At least two charged tracks produced. 38 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 38/43 43

Signatures at FCCs arxiv::1612.02728 FCCee: Displaced vertices (Z-pole). Electroweak precision measurements (mostly Z-pole). Higgs boson production and decay modes. FCC-hh/e: LFV, LNV, displeased vertex. 39 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 39/43 43

Current picture JHEP 1505 (2015) 053 Present limits are dominated by LEP. Higgs decays: Best constraints from H γγ 40 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 40/43 43

Sensitivity arxiv:1411.5230v2 Preliminary studies show excellent potential! Confirmation needed, based on accurate detector simulation Complementarity with other CERN projects (e.g., SHiP, see N.Serra talk tmr.) 41 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 41/43 43

Synergy between FCC-xy Systematics assessment of heavy neutrino signatures at colliders. First looks FCC-hh and FCC-he sensitivities. Golden channels: FCC-hh: LFV signatures and displeased vertexes. FCC-he LFV signatures and displeased vertexes. FCC-hh: EWPO and displeased vertexes. O.Fischer 42 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 42/43 43

Summary The FCC program is constantly growing. CDR in 2018! One of the core program of FCC are HNL! future colliders will exclude large part of parameter space! 43 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 43/43 43

Backup 44 / Marcin Chrzaszcz (Universität Zürich) Search for massive neutrinos at LHCb and discovery potential of the FCC 44/43 43