Staus at the LHC. Koichi Hamaguchi (Tokyo U.) based on the works. KH, M.M.Nojiri, A.de Roeck (hep-ph/ );

Size: px

Start display at page:

Download "Staus at the LHC. Koichi Hamaguchi (Tokyo U.) based on the works. KH, M.M.Nojiri, A.de Roeck (hep-ph/ );"

Briana Parsons
5 years ago
Views:

1 Staus at the LHC Koichi Hamaguchi (Tokyo U.) at KEKPH 7, based on the works KH, M.M.Nojiri, A.de Roeck (hep-ph/6126); KH, M.M.Nojiri, Y.Kuno, T.Nakaya ( 4); W.Buchmüller, KH, M.Ratz, T.Yanagida ( 4); Mar. 7

2 Long-lived Staus at the LHC Koichi Hamaguchi (Tokyo U.) at KEKPH 7, based on the works KH, M.M.Nojiri, A.de Roeck (hep-ph/6126); KH, M.M.Nojiri, Y.Kuno, T.Nakaya ( 4); W.Buchmüller, KH, M.Ratz, T.Yanagida ( 4); Mar. 7

3 Long-lived Staus at the LHC and in the early universe Koichi Hamaguchi (Tokyo U.) at KEKPH 7, based on the works KH, M.M.Nojiri, A.de Roeck (hep-ph/6126); Mar. 7 KH, M.M.Nojiri, Y.Kuno, T.Nakaya ( 4); W.Buchmüller, KH, M.Ratz, T.Yanagida ( 4); + KH, T.Hatsuda, M.kamimura, Y.Kino, T.T.Yanagida (hep-ph/72274) W.Buchmüller, KH, M.Ibe, T.T.Yanagida ( 6). this week

Outline Motivation + Introduction Long-lived staus @ LHC

4 Outline Motivation + Introduction Long-lived LHC Stopper-detector Study of stau decay Remark (catalyzed BBN) Summary

5 Motivation: Can we test the Supergravity at the LHC?

6 What would prove the Supergravity?

7 What would prove the Supergravity?

8 Gravitino Gravitino Interaction: extremely weak suppressed by 1 MP (or 1 F Gravitino Mass: model dependent ev kev MeV GMSB 1 MP mge GeV ) TeV gmsb AMSB, mmsb gravity-msb LSP: Cold Dark Matter

9 We assume SUSY scenarios with Gravitino LSP (Dark Matter)

10 Dark Matter in SUSY In SUSY models + conserved R-parity, the Lightest SUSY Particle (= LSP) is stable. If neutral, Dark Matter candidate.

11 Dark Matter candidates in SUSY Standard Model In SUSY Standard Model in supergravity framework,... squarks :! "L u d" L # i u" Ri d" Ri ", gauginos and higgssinos : χ i % gravitino : G sleptons : $ χ± i, g%! ν" L e" L # i e" Ri

12 Dark Matter candidates in SUSY Standard Model In SUSY Standard Model in supergravity framework,... squarks :! "L u d" L # i u" Ri d" Ri ", gauginos and higgssinos : χ i % gravitino : G sleptons : $ χ± i, neutral and color-singlet g%! ν" L e" L # i e" Ri

13 Dark Matter candidates in SUSY Standard Model In SUSY Standard Model in supergravity framework,... squarks :! "L u d" L # i u" Ri d" Ri ", gauginos and higgssinos : χ i % gravitino : G sleptons : $ χ± i, neutral and color-singlet g%! ν" L e" L # i e" Ri excluded by direct detection experiments (cf. Falk, Olive, Srednicki, 94)

14 Dark Matter candidates in SUSY Standard Model In SUSY Standard Model in supergravity framework,... squarks :! "L u d" L # i u" Ri d" Ri ", gauginos and higgssinos : χ i % gravitino : G sleptons : $ χ± i, g%! ν" L e" L # i e" Ri excluded by direct detection experiments (cf. Falk, Olive, Srednicki, 94) neutral and color-singlet Only Neutralino and Gravitino are viable candidates for the LSP dark matter!

15 Dark Matter candidates in SUSY Standard Model In SUSY Standard Model in supergravity framework,... squarks :! "L u d" L # i u" Ri d" Ri ", gauginos and higgssinos : χ i % gravitino : G sleptons : $ χ± i, g%! ν" L e" L # i e" Ri excluded by direct detection experiments (cf. Falk, Olive, Srednicki, 94) neutral and color-singlet Only Neutralino and Gravitino are viable candidates for the LSP dark matter! this talk

16 NLSP (Next-to-Lightest SUSY Particle) In Gravitino LSP scenario, the NLSP is long-lived. Interaction 1 F Lifetime e.g. for mnlsp! 2 GeV τnlsp O(day) for mge 1 GeV τnlsp O(1 min) for mge 1 GeV τnlsp O(1 sec) for mge.1 GeV 1 MP mge

17 We assume SUSY scenarios with Gravitino LSP (Dark Matter) + Stau NLSP. Then, we may have a chance to test the supergravity at future colliders...! W.Buchmüller, K.Hamaguchi, M.Ratz, T.Yanagida 4

18 Planck scale measurement W.Buchmüller, K.Hamaguchi, M.Ratz, T.Yanagida 4

19 Planck scale measurement W.Buchmüller, K.Hamaguchi, M.Ratz, T.Yanagida 4

20 Planck scale measurement W.Buchmüller, K.Hamaguchi, M.Ratz, T.Yanagida 4 Is this Planck scale measurement possible at the LHC???

21 Long-lived LHC Γ(τ G τ ) " m5τ 2 48πm2G Mpl! 1 m2g m2τ Lifetime (decay length) of NLSP stau mg ττ cττ ev e.g., for mτ = 1 GeV, MeV GeV kev ps mm ns m "4 µs km ms sec day

22 Long-lived LHC Γ(τ G τ ) " m5τ 2 48πm2G Mpl! 1 m2g m2τ Lifetime (decay length) of NLSP stau mg ττ cττ ev e.g., for mτ = 1 GeV, MeV GeV kev ps mm ns m Detector Size "4 µs km ms sec day

23 Long-lived LHC Γ(τ G τ ) " m5τ 2 48πm2G Mpl! 1 m2g m2τ "4 Lifetime (decay length) of NLSP stau mg ττ cττ ev e.g., for mτ = 1 GeV, MeV GeV kev ps mm ns m Detector Size µs ms sec day km No In-flight decay

Long-lived staus @ LHC We will see long-lived

mass (by time of flight), and furthermore

24 Long-lived LHC We will see long-lived charged particle (like muon). τ Fig. from ATLAS webpage τ Fig. from CMS webpage We can precisely measure its mass (by time of flight), and furthermore reconstruct masses of heavier SUSY particles. Here, we would like to discuss the next step.

25 Long-lived LHC We would like to study the decay of stau (into gravitino). We need to stop the staus.

26 Long-lived LHC We would like to study the decay of stau (into gravitino). We need to stop the staus.

27 Long-lived LHC We would like to study the decay of stau (into gravitino). We need to stop the staus.

28 Long-lived LHC How thick the stopping material should be? typically!±, χ! τ! g!, q! χ (number of events)/bin/5fb Review of Particle Physics !" Fig. from Hamaguchi, Kuno, Nakaya, Nojiri 4

29 Long-lived LHC How thick the stopping material should be? typically for 1 GeV stau!±, χ! τ! g!, q! χ 5m Fe (number of events)/bin/5fb Review of Particle Physics !" Fig. from Hamaguchi, Kuno, Nakaya, Nojiri 4

30 Long-lived LHC How thick the stopping material should be? typically for 1 GeV stau!±, χ! τ! g!, q! χ 5m Fe (number of events)/bin/5fb Review of Particle Physics !" Fig. from Hamaguchi, Kuno, Nakaya, Nojiri 4

31 Long-lived LHC How thick the stopping material should be? typically for 1 GeV stau!±, χ! τ! g!, q! χ 5m Fe (number of events)/bin/5fb Review of Particle Physics !" Fig. from Hamaguchi, Kuno, Nakaya, Nojiri 4 If thick enough, part of produced staus may be stopped.

32 Long-lived LHC Actually, the LHC detector themselves can stop part of staus... Fig. from CMS webpage

33 Long-lived LHC Actually, the LHC detector themselves can stop part of staus... Fig. from CMS webpage

34 Long-lived LHC Actually, the LHC detector themselves can stop part of staus... We may identify the position of the stopped stau, but... Fig. from CMS webpage

35 Long-lived LHC Actually, the LHC detector themselves can stop part of staus... it is difficult to identify its decay, which is out-of-time and not originating from beam interaction point.... needs New Idea.

36 Long-lived LHC Actually, the LHC detector themselves can stop part of staus...? it is difficult to identify its decay, which is out-of-time and not originating from beam interaction point.... needs New Idea.

37 Long-lived LHC Actually, the LHC detector themselves can stop part of staus...? We may identify the position of the stopped stau, but... it is difficult to identify its decay, which is out-of-time and not originating from beam interaction point.... needs New Idea.

38 Long-lived LHC Ideas: Place an additional stopper-detector next to the main detector. [ Hamaguchi, Kuno, Nakaya, Nojiri, 4 ] Place a water tank as stopper, and then drain the water to a reservoir. [ Feng, Smith, 4 ] Use the stau stopped in the surrounding rock. [ De Roeck, Ellis, Gianotti, Moortgat, Olive, Pape 5 ]

Long-lived staus @ LHC Ideas: Only this type can identify the timing and position of the stopping

[ Hamaguchi, Kuno, Nakaya, Nojiri, 4 ] Place a water tank as stopper, and then drain the water to a

39 Long-lived LHC Ideas: Only this type can identify the timing and position of the stopping stau precisely. Place an additional stopper-detector next to the main detector. [ Hamaguchi, Kuno, Nakaya, Nojiri, 4 ] Place a water tank as stopper, and then drain the water to a reservoir. [ Feng, Smith, 4 ] Use the stau stopped in the surrounding rock. [ De Roeck, Ellis, Gianotti, Moortgat, Olive, Pape 5 ]

40 stopper = detector?? High segmentation is crucial to reduce the background... τ! τ! τ! High segmentation τ! τ! τ! Low segmentation

41 stopper = detector?? High segmentation is crucial to reduce the background... τ! τ! τ! τ! τ! τ! cf. atm. neutrino CC event < 1 event/kton/year OK. charged particle at the surface of detector < 1/cm2/sec (?) ==> For SOUDAN II type detector, this corresponds to < 1% dead time of drift tube OK.

42 ATLAS vs CMS diameter length weight ATLAS 22m 44m 7kt CMS 15m 21m 12.5kt CMS is smaller maybe possible to place stopper-detector(s)

43 stopper-detector We assume two stoppers next to CMS. Hamaguchi, Nojiri, De Roeck 6 CMS stopper-detector m m m 5g/cm3 (total weight 8kt)

44 stopper-detector We assume two stoppers next to CMS. Hamaguchi, Nojiri, De Roeck 6 CMS main cavern 26m diameter x 6m long テキスト Fig. from a document at a webpage of TS/CV/DC section of CERN.

45 stopper-detector We assume two stoppers next to CMS. Hamaguchi, Nojiri, De Roeck 6 CMS stopper-detector 15m 3.5m maybe possible to install stopper-detectors.

46 distribution of stopped stau x[m] y-position[m] z-positon[m] Λ = 4 TeV GM point x[m] Hamaguchi, Nojiri, De Roeck,

47 How many staus are stopped? up to O(1) staus are trapped! table, too Hamaguchi, Nojiri, De Roeck, 6

lifetime measurement SUSY breaking scale for N = 1 18 1 16 8 14 12 2 ln L number of events / bin

F = mge MP = SUSY breaking scale 1 8 6 4 6 4 2 2 1 2 3 4 5 6 7 8 9 tdecay tstop [in unit of

48 lifetime measurement SUSY breaking scale for N = ln L number of events / bin lifetime Γ 1 F 2,! F = mge MP = SUSY breaking scale tdecay tstop [in unit of lifetime] Note: possible only in a real-time detector lifetime [arbitrary unit] 1.5 Hamaguchi, Nojiri, de Roeck 6 τ /τ = 1 15% for Nτe = 1 τ /τ = 3 4% for Nτe = 1

49 Motivation: Can we test the Supergravity at the LHC?

50 Planck scale measurement W.Buchmüller, K.Hamaguchi, M.Ratz, T.Yanagida 4

51 Planck scale measurement Crucial to determine the tau energy precisely. 25 m τ 2 m = mx [GeV] τ m 15 τ m 1 τ = 5 1 mge = = 1 = m! = 3 G ev G ev G ev G ev 1y s yr 2 τ G ev 4 r 6 nth o m 8 Eτ [GeV] day m2τe 2mτe Eτ + m2τ 16 Figs. from Hamaguchi, Nojiri, De Roeck, 6 (cf. for ILC, see Martyn 6.)

52 Planck scale measurement Crucial to determine the tau energy precisely. (a) (b) 1 Low Stat. Best Fit 14 m τ 1 = m = τ 4 2 m 15 τ 2 m 1 τ 5 1 mge = 2 m = τ G ev 3 G ev G ev = EjetG [GeV] ev s yr 2! ! 1 Ge = 15%/ Ejet /GeV V = Ejet /Ejet 25 2 ln L yr 6 nth o m 8 Eτ [GeV] Eτ [GeV] (c) 1.5 day Pτ number of events / bin mx [GeV] m2τe 2mτe Eτ + m2τ Eτ [GeV] Figs. from Hamaguchi, Nojiri, De Roeck, 6 (cf. for ILC, see Martyn 6.)

53 Planck scale measurement Crucial to determine the tau energy precisely. (a) (b) 1 Low Stat. Best Fit 14 m τ 1 = m = τ 4 2 m 15 τ 2 m 1 τ 5 1 mge = 2 m = τ G ev 3 G ev G ev = EjetG [GeV] ev s yr 2! ! 1 Ge = 15%/ Ejet /GeV V = Ejet /Ejet 25 2 ln L yr 6 nth o m 8 Eτ [GeV] Eτ [GeV] (c) 1.5 day Pτ number of events / bin mx [GeV] m2τe 2mτe Eτ + m2τ Eτ [GeV] Figs. from Hamaguchi, Nojiri, De Roeck, 6 (cf. for ILC, see Martyn 6.)

54 mass reconstruction σ mx /mτ yrs mx /mτ yrs yr mg /mτ mg /mτ yr month yrs mτ = 3 GeV, Nτ = yr month yrs month mτ = 2 GeV, Nτ = 1 1 yrs mτ = 3 GeV, Nτ = mg /mτ yr month ! M P [GeV].5.7 m! X /mτ.6 m! X /mτ.7.6 yr month mτ = 3 GeV, Nτ = 1 1 yrs mτ = 3 GeV, Nτ = 1 yr mx /mτ month mx /mτ.8.2 mg /mτ mτ = 2 GeV, Nτ = 1 1 yrs yr.4.2.8! M P [GeV].4.4 m! X /mτ.5 m! X /mτ month mτ = 2 GeV, Nτ = 1 1 yrs yr mx /mτ mτ = 2 GeV, Nτ = mx /mτ month ! M P [GeV] yrs yr month! M P [GeV].4 1 yrs yr month m! X /mτ.7.6 m! X /mτ.7 yr month.8 1 yrs! M P [GeV] yr month.8 mτ = 15 GeV, Nτ = 1 mτ = 15 GeV, Nτ = 1 mτ = 15 GeV, Nτ = 1 1 yrs! M P [GeV] mτ = 15 GeV, Nτ = 1 Mp measurement mg /mτ mg /mτ Hamaguchi, Nojiri, de Roeck, 6 Possible if mg e > (.2.3)mτ e.8

55 Remark mge > (.2.3)mτe may be inconsistent with BBN bounds (especially catalyzed BBN).

( negatively charged stau positively charged nuclei ) Pospelov 6; Kohri, Takayama 6;

56 Remark mge > (.2.3)mτe may be inconsistent with BBN bounds (especially catalyzed BBN). Recently, bound-state effects have been discussed. ( negatively charged stau positively charged nuclei ) Pospelov 6; Kohri, Takayama 6; Kaplinghat, Rajaraman 6; Cyburt, Ellis, Fields, Olive, Spanos 6, KH, Hatsuda, Kamimura, Kino, Yanagida 7 standard BBN catalyzed BBN Pospelov 6 enhanced?!!

57 Remark mge > (.2.3)mτe may be inconsistent with BBN bounds (especially catalyzed BBN). KH, Hatsuda, Kamimura, Kino, Yanagida 7 Solved the Schroedinger eq. for 3-body system (He4, d, X) exactly, using the state-of-the-art coupled-channel technique. D + ( HeX) 4 Bound state Li6 6 Li + X

58 Remark mge > (.2.3)mτe may be inconsistent with BBN bounds (especially catalyzed BBN). KH, Hatsuda, Kamimura, Kino, Yanagida 7 Solved the Schroedinger eq. for 3-body system (He4, d, X) exactly, using the state-of-the-art coupled-channel technique. D + ( HeX) 4 Bound state astrophysical S-factor Li6 6 Li + X

59 Remark mge > (.2.3)mτe may be inconsistent with BBN bounds (especially catalyzed BBN). KH, Hatsuda, Kamimura, Kino, Yanagida 7 Solved the Schroedinger eq. for 3-body system (He4, d, X) exactly, using the state-of-the-art coupled-channel technique. D + ( HeX) 4 6 Li + X astrophysical S-factor X abundance Li6 Bound -12 thermal relic log1!nx%s$ state up -14 per bou n -15 d Log1!tau_X"sec#$ 7 8 X Lifetime

60 Remark mge > (.2.3)mτe may be inconsistent with BBN bounds (especially catalyzed BBN). KH, Hatsuda, Kamimura, Kino, Yanagida 7 But if there is an entropy production of O(a few 1) after NLSP decoupling, the bounds can be avoided. log1!nx%s$ abundance -12 thermal relic up -14 per bou n -15 d Log1!tau_X"sec#$ 7 8 Lifetime O(3)

61 Summary For the gravitino LSP, the NLSP becomes long-lived. To study the decay of a long-lived charged NLSP, a stopper-detector seems necessary. O(1)kton stopper-detector may be placed next to the CMS detector. Stau lifetime is measured well. If mg e > (.2.3)mτ e, the mass reconstruction (and hence Mp measurement!) may be possible. Catalyzed BBN is a problem, but may be solved.

62 Summary For the gravitino LSP, the NLSP becomes long-lived. To study the decay of a long-lived charged NLSP, a stopper-detector seems necessary. O(1)kton stopper-detector may be placed next to the CMS detector. Stau lifetime is measured well. If mg e > (.2.3)mτ e, the mass reconstruction (and hence Mp measurement!) may be possible. Catalyzed BBN is a problem, but may be solved. Anyway, if long-lived charged particles are seen at the LHC,... trap them!!

63 NLSP Which particle is the NLSP? Usually m!e! mqe, and mχe1 < mχe± < mge 1 therefore, the NLSP is neutralino or slepton. Among sleptons, typically a charged slepton, especially the stau τ! is the lightest. (but sneutrino NLSP is also possible.) In general, other SUSY particle can also be NLSP.

64 NLSP Which particle is the NLSP? Usually m!e! mqe, and mχe1 < mχe± < mge 1 therefore, the NLSP is neutralino or slepton. Among sleptons, typically a charged slepton, especially the stau τ! is the lightest. (but sneutrino NLSP is also possible.) In general, other SUSY particle can also be NLSP.

65 stopper = detector?? Hamaguchi, Kuno, Nakaya, Nojiri, 4

66 study of 3 body decay

67 3-body decay... gravitino vs axino LSP may be another weakly interacting!. particle, like axino a We want to distinguish the decay into the gravitino from the decay into axino by studying the 3-body decay:! or a!) τ! Xτ γ, (X = G cf. Brandenburg, Covi, Hamaguchi, Roszkowski, Steffen, 5 Buchmüller, Hamaguchi, Ratz, Yanagida 4

68 3-body decay... gravitino vs axino γ Eγ θ τ X! or a!?? X=G! Eγ /Eγ = 1%/ Eγ /GeV

69 3-body decay... gravitino vs axino We divide Eγ and θ into bins, Eγ = mτe /8 θ = π/3 (cut : Eγ > 1 GeV) (cut : θ > π/6) Required number of staus to see 3sigma diff. mae, mge! mτe, ξ = numerical parameter (not yet calculated)

70 Buchmüller, Hamaguchi, Ibe, Yanagida 6

Dark matter and missing energy - what is there apart from SUSY?

Dark matter and missing energy - what is there apart from SUSY? Koichi Hamaguchi (Tokyo U.) at LHC New Physics Forum, Heidelberg, February 09 long-lived charged particle { Dark matter and missing energy