Cosmology at Colliders: Possible LHC searches for RPV baryogenesis

Transcription

1 Cosmology at Colliders: Possible LHC searches for RPV baryogenesis Haipeng An Perimeter Ins;tute In collaboration with Yue Zhang arxiv:

2 Mo;va;ons We are made of baryons and we have been living for a long ;me, not a lot of an;- baryon around us. There is a baryon- an;- baryon asymmetry Where does this asymmetry come from? Ini;al condi;on? Dynamics? If it is from some dynamics (mechanism, scenario...), can we test it in today s laboratory?

3 Mo;va;ons Higgs is discovered Naturalness problem is s;ll unsolved SUSY: sub- TeV scale top- partner is needed ~ t t H t H + H H Constraints are strong for R- parity conserving SUSY

4 Mo;va;ons R- parity viola;on (RPV) extension can be used to kill the large missing energy, and therefore relax the constraints W RPV = LLe c + 0 QLd c + 00 u c d c d c + µ 0 LH u

5 Mo;va;ons R- parity viola;on (RPV) extension can be used to kill the large missing energy, and therefore relax the constraints W RPV = LLe c + 0 QLd c + 00 u c d c d c + µ 0 LH u ü Usually invoked to trade large MET to jets. ü No proton decay

6 Mo;va;ons 00 u c d c d c Hubble expansion h vin 002 T 8 H 1.66g 1/2? T 2 m pl 00 & 10 7 The primordial baryon number is washed out below TeV scale! New baryogenesis is in need! Displaced ver;ces at the LHC (see Barry el al for detail)

7 Mo;va;ons 00 u c d c d c Hubble expansion h vin 002 T 8 H 1.66g 1/2? T 2 m pl 00 & 10 7 The primordial baryon number is washed out below TeV scale! New baryogenesis is in need! Displaced ver;ces at the LHC (see Barry el al for detail)

8 Goal To propose an directly detectable low scale baryogenesis scenario within the RPV SUSY framework.

9 Outline Baryogenesis from squark decay Collider constraints and signatures Embed the baryogenesis scenario into realis;c models MSSM with a horizontal symmetry MSSM case Summary

10 Baryogenesis from squark decay In RPV SUSY models, the RPV couplings are the sources to washout the baryon number. Can we make use of them to re- generate the baryon number?

11 Baryogenesis from squark decay In RPV SUSY models, the RPV couplings are the sources to washout the baryon number. Can we make use of them to re- generate the baryon number? Sakharov condi;ons: C and CP viola;ons Baryon number viola;on Out- of- equilibrium

12 Baryogenesis from squark decay In RPV SUSY models, the RPV couplings are the sources to washout the baryon number. Can we make use of them to re- generate the baryon number? Sakharov condi;ons: ü C and CP viola;ons (Complex phases of λ and λ ) ü Baryon number viola;on (B- viola;ng RPV) ü Out- of- equilibrium (squark decay)

13 Baryogenesis from squark decay Squarks are complex scalars CPT theorem q = q

14 Baryogenesis from squark decay Squarks are complex scalars CPT theorem q = q At least two decay channels with different baryon numbers must be invoked. Nanopoulos, Weinberg, 1979

15 Baryogenesis from squark decay Squarks are complex scalars CPT theorem q = q At least two decay channels with different baryon numbers must be invoked. Nanopoulos, Weinberg, 1979 W RPV = LLe c + 0 QLd c + 00 u c d c d c + µ 0 LH u

16 Baryogenesis from squark decay Squarks are complex scalars CPT theorem q = q At least two decay channels with different baryon numbers must be invoked. Nanopoulos, Weinberg, 1979 W RPV = LLe c + 0 QLd c + 00 u c d c d c + µ 0 LH u invoked Proton decay!

17 Baryogenesis from squark decay Proton decay constraints If first genera;on quarks involved,. If only second and third genera;ons are involved, the proton decay is suppressed by the CKM. In prac;ce, the model we choose L' 00 i b c P R c d i + 0 i( tp R µ c bp R c ) d i 0 00 < < µ

18 Baryogenesis from squark decay A toy model with down- type squarks For right handed quarks, we can assume that there is no rota;ons, so we can avoid first genera;on by hand. Quarks are in mass eigenstates

19 Baryogenesis from squark decay A toy model with down- type squarks For right handed quarks, we can assume that there is no rota;ons, so we can avoid first genera;on by hand. Quarks are in mass eigenstates 0 No first i1 0 genera;on 0 0 V 21 i2 + V 31 i3 0 V 31 V 21 0 i3 0 i2

20 Baryogenesis from squark decay Decay channels: L' 00 i b c P R c d i + 0 i( tp R µ c bp R c ) d i All other branching ra;os can be determined from " i Br i and.

21 Baryogenesis from squark decay Decay channels: L' 00 i b c P R c d i + 0 i( tp R µ c bp R c ) d i All other branching ra;os can be determined from " i Br i and.

22 Baryogenesis from squark decay CP viola;on d 1 d1 b c d 2 t µ t µ

23 Baryogenesis from squark decay CP viola;on d 1 t d1 µ t µ b c d 2

24 Baryogenesis from squark decay CP viola;on d 1 t d1 µ t µ b c d 2 Im[ ]

25 Baryogenesis from squark decay Boltzmann equa;ons Squarks freeze out and decay Y = n/s Evolu;on of baryon number 00 i dy B dz = 2" i H(z)z (Y di Y eq d i ) + washout terms

26 Baryogenesis from squark decay Boltzmann equa;ons Squarks freeze out and decay Dominated by strong interac;on Evolu;on of baryon number 00 i dy B dz = 2" i H(z)z (Y di Y eq d i ) + washout terms

27 Baryogenesis from squark decay Boltzmann equa;ons Squarks freeze out and decay Dominated by strong interac;on Evolu;on of baryon number 00 i dy B dz = 2" i H(z)z (Y di Y eq d i ) + washout terms Source term: d i! b c

28 Baryogenesis from squark decay Thermal evolu;on Y d

29 Baryogenesis from squark decay Thermal evolu;on Y d too small Relic abundance too small

30 Baryogenesis from squark decay Thermal evolu;on Y d Baryogenesis occurs

31 Baryogenesis from squark decay Large CP viola;on is needed: "Br & 0.01 B n B /n

32 Outline Baryogenesis from squark decay Collider signatures and constraints Embed the baryogenesis scenario into realis;c models MSSM with a horizontal symmetry MSSM case Summary

33 Collider signature In the early Universe Inside the LHC d i, d i Boltzmann distribu;on d i, d i f parton ˆgg! di d i

34 Collider signature In the early Universe Inside the LHC d i, d i Boltzmann distribu;on Non- equilibrium decay, preferably d i! tµ (b ) d i! bc c c d i, d i f parton ˆgg! di d i Just decay, preferably (Non- equilibrium for sure) di! tµ (b ) d i! bc c c

35 Collider signature In the early Universe Inside the LHC d i, d i Boltzmann distribu;on Non- equilibrium decay, preferably d i! tµ (b ) d i! bc c c d i, d i f parton ˆgg! di d i Just decay, preferably (Non- equilibrium for sure) di! tµ (b ) d i! bc c c Baryogenesis once more, at the LHC.

36 Collider signature g g d d µ t b c c c b q q 5 jets For simplicity, only consider hadronic top Signal: 5 jets + muon Charge asymmetry µ +5j > µ+ +5j

37 Collider signature Cuts: A hard muon and at least three hard jets p T (µ) > 170 GeV p T (j 1,2 ) > 200 GeV p T (j 3 ) > 150 GeV To reduce the W+jets background MET < 30 GeV Main background from QCD: jet faking muon. Fake rate < Reconstruct the 10 4 ATL- PHYS- PUB d, d peak For each events, find the closest M(j 1,j 2 ) and M(mu,rest).

38 14 TeV LHC Collider signature

39 Collider signature 14 TeV LHC Different heights Charge asymmetry

40 Collider constraints L' 00 i b c P R c d i + 0 i( tp R µ c bp R c ) d i

41 Collider constraints L' 00 i b c P R c d i + 0 i( tp R µ c bp R c ) d i

42 m d = 600 GeV Collider constraints

43 Outline Baryogenesis from squark decay Collider signatures and constraints Embed the baryogenesis scenario into realis;c models MSSM with a horizontal symmetry MSSM case Summary

44 Realis;c model CP viola;on (re- visit) In general 1 Br 1 = Im( ( )( 00 ( m d1 m d2 d) 2 2 m d2 2 ) ) F 2(m 2 d2 /m 2 d1 ) apple 1 3+(2+3x) log 1 x 1+x x

45 Realis;c model CP viola;on (re- visit) In general 1 Br 1 = Im( ( )( 00 A resonance is in need! ( m d1 m d2 d) 2 2 m d2 2 ) ) F 2(m 2 d2 /m 2 d1 ) apple 1 3+(2+3x) log 1 x x x

46 Realis;c model CP viola;on (re- visit) Resonant case ( m d1 m d2 d) 1 Br 1 = Im( ( )( 00 2 ) (m d1 m d2 )( d2 /2) ) (m d1 m d2 ) 2 +( d2 /2) 2

47 Realis;c model CP viola;on (re- visit) Resonant case ( m d1 m d2 d) 1 Br 1 = Im( ( )( 00 2 ) ) (m d1 m d2 )( d2 /2) (m d1 m d2 ) 2 +( d2 /2) 2 d 2 14 orders smaller than m d How to generate such a small mass gap naturally?

48 Realis;c model SU(2) horizontal symmetry between d 1, d2 Explicitly broken only by the RPV interac;ons Loop induced mass splinng is just comparable to In SUSY models, we introduce superfields D1,D 0 2, 0 D 1, 0 D 2 0 For grand unifica;on, we lio them to vector- like 5 representa;on in SU(5). Gauge couplings are s;ll perturba;ve at the Unifica;on scale.

49 Realis;c model A spectrum d 0 Spinor part of D d 0! tµ t d stop Scalar part of D t! qq SM quarks

50 MSSM Can we realize this model in MSSM? Who can be the decaying squarks? requires a tuning Finite temperature correc;on due to different Yukawa couplings (Higgs thermal loop). Only Yukawa couplings for d and s are small enough to suppress the thermal effect.

51 Summary We proposed a baryogenesis model, in which the baryon number is generated through the decay of squarks. We could repeats the baryogenesis process inside the LHC. The smoking gun signal is the lepton- charge asymmetry. This scenario can be realized in RPV SUSY models.