SHiP: Search for Hidden Particles A new experiment proposal at CERN

Transcription

1 SHiP: Search for Hidden Particles A new experiment proposal at CERN Walter M. Bonivento INFN-Cagliari on behalf of the SHIP collaboration (243 authors, 45 institutions from 14 countries) 1

2 The TP: submitted 14 April to CERN/SPS-C Under review 2 LDMA Camogli 2015, 26/6/2015

3 3 LDMA Camogli 2015, 26/6/2015

4 What is SHIP SHIP is a proposal for a beam dump experiment at CERN/SPS (400GeV p) Main goals (so far ): 1) detection of long lived particles, very weakly interacting or sterile: statistical sensitivity with respect to previous experiments of similar type (for HNL) x10000 > Many theories and models on the market (models of DM, SUSY, theories providing explanation for ν masses and baryogenesis, ) have some sensitivity region to be explored with SHIP! 2) textbook measurements of ν τ interactions with statistical sensitivity with respect to previous experiments of similar type x200 4 LDMA Camogli 2015, 26/6/2015

5 How? The highest E proton beam of the world dumped with maximum intensity and followed by the closest, longest and widest possible and technically feasible decay tunnel 5 LDMA Camogli 2015, 26/6/2015

6 Shaking hands 2" SM was recently fully confirmed by the Higgs-boson discovery! 6 LDMA Camogli 2015, 26/6/2015

7 However However: no NP anywhere! Also, naturalness is now severely challenged. The peculiar Higgs mass suggest that, even in absence of NP, the Universe is metastable. SM could well be valid up to Planck scale but we have to explain some facts: neutrino oscillations, bariogenesis, dark matter (+inflation, dark energy ) JHEP 1312 (2013) LDMA Camogli 2015, 26/6/2015

8 Where is the new physics? EWSB, Hierarchy WIMP DM... 1 e µ,,p W, Z t? Coupling to SM ? Intensity Frontier - SHiP g 2 M 2 G F Energy Frontier - LHC Mass of particle (GeV) RH neutrinos Dark Matter Hidden sector... 8 LDMA Camogli 2015, 26/6/2015

9 The Hidden Sector renormalizable couplings, i.e. NOT suppressed! +other of higher dimensions (e.g. axion-like portal) (stolen from A.Fradette, New Physics at the Intensity Frontier - Victoria, BC,Sept 2014) 9 LDMA Camogli 2015, 26/6/2015

10 Neutrino portal 10 LDMA Camogli 2015, 26/6/2015

11 11 LDMA Camogli 2015, 26/6/2015

12 The νmsm and its variants 3 Majorana (HNL) partners of ordinary ν, with M N <M W In a peculiar parameter space (N 2 and N 3 almost degenerate in mass and with m=o(gev) and N 1 decoupled with m=o(kev) ), νmsm explains: neutrino masses (see-saw), baryogenesis (via lepto-genesis) and DM (N 1 )! (but most probably DM has to be generated outside the νmsm, by e.g. the decay of an inflaton >see Higgs portal) mass charge name Quarks Leptons 2.4 MeV ⅔ u up Left Left Left Left Right Right Right ⅔ Left Left Left Left 1.27 GeV c charm 4.8 MeV 104 MeV -⅓ -⅓ d s down strange 0 ν Three Generations of Matter (Fermions) spin ½ I II III ν e electron neutrino Right Right Right GeV ⅔ t top Left 4.2 GeV -⅓ b bottom Left Left Left Right Right ~GeV ~GeV 0 μ 0ν τ 1 N2 N tau 3 ~10 kev N muon neutrino neutrino MeV MeV GeV e μ τ electron muon tau Right Bosons (Forces) spin g gluon γ photon 91.2 GeV Z 0 0 weak force 80.4 GeV W ± ± 1 weak force H 126 GeV 0 0 Higgs boson spin 0 No hierarchy problem (if also the inflaton or the NP yielding N1 has mass below EW scale) Naturalness of the above parameter space comes from a U(1) lepton symmetry, broken at 10-4 level. νmsm: T.Asaka, M.Shaposhnikov PL B620 (2005) 17 M.Shaposhnikov Nucl. Phys. B763 (2007) LDMA Camogli 2015, 26/6/2015

13 About N1 Stability > τ>τ(universe) Production > ll>νn 1, qq >νn 1 exclusion up to 2013 with single galaxies Decay > the radiative decay N 1 >γν provides a line in the X spectrum at E(γ)=m1/2 13 LDMA Camogli 2015, 26/6/2015

14 Harvard, NASA ecc. some 3 sigma observations in 2014 with stacked spectra of galaxies or clusters, with XMM Newton, Chandra Interaction strength Sin 2 (2θ) Tremaine-Gunn / Lyman-α DM overproduction Excluded by X-ray observations Not enough DM Dark matter mass M DM [kev] Boyarski et al. some new mission planned, more observation time for XMM-Newton >action going on! 14 LDMA Camogli 2015, 26/6/2015

15 N 2,3 production inverted mass hyerarchy Interaction with the Higgs v.e.v. >mixing with active neutrinos with U 2 in the νmsm strong limitations in the parameter space (U 2,m) a lot of HNL searches in the past but, for m>m K, with a sensitivity not of cosmological interest (e.g. LHCb with B decays obtained U , arxiv: ) this proposal: search in D meson decays (produced with high statistics in fixed target p collisions at 400 GeV ) Taking into account the existing beams and those possibly existing in the near future, this is the best experiment to problem the cosmologically interesting region,, 15 LDMA Camogli 2015, 26/6/2015

16 N 2,3 decays Very weak HNL-active ν >N 2,3 have very long life-time decay paths of O(km)!: for =1.8x10-5 s U 2 μ=10-7, τ N Various decay modes : the BR s depend on flavor mixing The probability that N 2,3 decays within the fiducial volume of the experiment U μ 2 > number of events U μ 4 16 LDMA Camogli 2015, 26/6/2015

17 SHIP sensitivity to HNL SHIP will scan most of the cosmologically allowed region below the charm mass Reaching the see-saw limit would require increase of the SPS intensity by an order of magnitude (does not currently seem realistic) 17 LDMA Camogli 2015, 26/6/2015

18 Comparison with others Interpretation in context of Left-Right symmetric model 18 LDMA Camogli 2015, 26/6/2015

19 Vector and scalar portal 19 LDMA Camogli 2015, 26/6/2015

20 (+A H H 2 ) 20 LDMA Camogli 2015, 26/6/2015

21 New Babar result 21 LDMA Camogli 2015, 26/6/2015

22 Minimal vector portal Two photon production modes considered: 1) in pseudo-scalar decays 2) in proton brehmsstrahlung Physics Letters B 731 (2014) LDMA Camogli 2015, 26/6/2015

23 Dark photons hadronic fixed target experiments overcome the kinematic limitation of e- fixed target allowing for m>1gev! 23 LDMA Camogli 2015, 26/6/2015

24 Higgs portal A real singlet scalar: SM: complex scalar doublet four degrees of freedom, three are eaten by the W±/Z bosons, one becomes the SM Higgs; SM+ real singlet scalar (φ or h): one extra degree of freedom and one extra physical scalar: could have mass m h < 5 GeV; could mass mix with the SM Higgs with mixing angle ρ: M. Winkler et al., arxiv: J. Clarke et al., arxiv: Motivated in many models BSM including SUSY, Coleman-Weinberg Interpretation as inflaton also possible (Bezrukov et al, JHEP05(2010)010 and arxiv: v1) 24 LDMA Camogli 2015, 26/6/2015

25 Scalar production/decay Production via meson decay, D CKM suppressed wrt B (5x10-10 ) and D cross section only 20k times larger than B cross section at 27GeV sin 2 ρ=1 Some uncertainty in the calculation of BR s 25 LDMA Camogli 2015, 26/6/2015

26 Light scalar 26 LDMA Camogli 2015, 26/6/2015

27 Axion-like portal 27 LDMA Camogli 2015, 26/6/2015

28 ALP or PNGB PNGBs or generic axions with couplings of order m X /F to SM matter X can arise as pseudo GB in many extensions of the SM they are naturally light if there is an approximate shift symmetry their interaction is proportional to the inverse of some SB scale F the coupling to a fermion field is 28 LDMA Camogli 2015, 26/6/2015

29 SUSY sgoldstinos SUSY breaking scale RPV neutralinos SUSY vector portal pseudo-dirac fermions 29 LDMA Camogli 2015, 26/6/2015

30 Summary of signals Leptonic, Leptonic-hadronic AND purely hadronic (also with kaons!) Some decays with missing energy (active neutrinos) Also with neutrals > need for energy resolution and separation photon - neutral pion! 30 LDMA Camogli 2015, 26/6/2015

31 The experiment 31 LDMA Camogli 2015, 26/6/2015

32 CERN accelerator complex 32 LDMA Camogli 2015, 26/6/2015

33 The beam Extracted SPS beam 400GeV; 19 like CNGS 4.5x10 pot/year design figures for the SHIP beam: slow extraction (1s) 5e13 ppp 4e19pot/year fully compatible with NA operation 33 LDMA Camogli 2015, 26/6/2015

34 34 LDMA Camogli 2015, 26/6/2015

35 Extraction test SHIP the current 49.2s SPS super-cycle with one single SHiP cycle starting at about 35s (under the text "last update") with a single injection of protons from PS to SPS (beam intensity in yellow), the acceleration to 400 GeV (energy illustrated in white), and the extraction during the flat top of 1s into the TT20 transfer line to the North Area as seen by the smooth drop of intensity with almost all beam extracted! The beam was sent to a beam stopper in the TT20 line. Few times 10^12 per spill every 49.2s for a couple of hours! 35 LDMA Camogli 2015, 26/6/2015

36 Target and muon filter Longitudinally segmented hybrid target: Mo(58cm)/W(58cm) the beam is spread on the target to avoid melting W It is followed by a muon filter. Mo The issue is not trivial since the muon flux is enormous: / SPS-spill( pot) 36 LDMA Camogli 2015, 26/6/2015

37 Muon active Filter 37 LDMA Camogli 2015, 26/6/2015

38 The detector 38 LDMA Camogli 2015, 26/6/2015

39 The vacuum vessel 39 LDMA Camogli 2015, 26/6/2015

40 Backgrounds 40 LDMA Camogli 2015, 26/6/2015

41 Background 41 LDMA Camogli 2015, 26/6/2015

42 Light ν s detector Emulsion based detector with the LNGS OPERA brick technolgy, but with a much smaller mass (750 bricks) very compact (2m), upstream of the HNL decay tunnel > with B field and followed by a muon detector (to suppress charm background) Even replacing 10 times the emulsion bricks during the run > still 5% of the OPERA 42 LDMA Camogli 2015, 26/6/2015

43 Neutrino target 43 LDMA Camogli 2015, 26/6/2015

44 Dark photon to dark matter ϵ χe χe m χ =200 MeV α'=0.1 POT=2x10 20 Use neutrino detector (emulsions) and detect neutral current interaction on atomic e- >not a background-free search (but calculable) m V (GeV) SHiP 30 Event BaBar J/ψ invisible Relic Density after cuts (angle 10-20mrad, E<20GeV), the beam backgrounds: 44 LDMA Camogli 2015, 26/6/2015

45 Time-table 45 LDMA Camogli 2015, 26/6/2015

46 Take home message! We know for sure that there is NP Yet, we don t know which one among the NP theories is the right one. Maybe none of them is right! We should keep an open mind Pursuing a diversity of experimental approaches is very important to maximize our likelihoods of finding NP 46 LDMA Camogli 2015, 26/6/2015