proton decay in susy gut in light of lhc
TRANSCRIPT
-
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
1/35
Proton decay in SUSY GUT in light of LHCPN
Northeastern University, Boston, MA 02115
International Symposium on Opportunities in UndergroundPhysics
24-27 May, 2013, Asilomar, California
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
2/35
-
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
3/35
Unification and Proton decay
Grand unification leads to an explanation of the three coupling constants1, 2, 3 in terms of a single coupling at the GUT scale.
Quantization of charge
|1 + Qe
Qp| < O(1021).
Quark lepton unification1
Proton decay is a consequence of quark -lepton unification1, 2 and is a common
feature of high scale models3 .
4 D GUTs
5 D and 6D models
string and D brane models
1JC Pati, A. Salam, PRL 31, 661(1973); PRD 10, 275 (1974).
2H. Georgi and S. L. Glashow, Phys. Rev. Lett. 32, 438 (1974).
3For a review on proton stability see
PN, P. Fileviez Perez, Phys. Report, Vol. 441, No.5-6,(2007).
http://find/http://goback/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
4/35
Why proton decay is of great importance for fundamental physics.
The main points about proton decay are
Observation of proton decay will test the basic idea of quark-lepton unification,i.e., that they are members of the same common multiplet. This phenomenon isnot testable in any other low energy process.
It will probe length scales which are extra-ordinarily small, i.e., O(1033)m.
Proton decay can provide a test for supersymmtry: In supersymmetry thedominant mode is typically p K+ and its observation will give support tothe existence of SUSY at the fundamental level.
Proton decay in principle can provide clues to the existence of strings and
possibly of extra dimensions.
Proton decay can provide a clue to the possible origin of matter generations.
http://find/http://goback/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
5/35
-
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
6/35
Proton decay from Lepto-quark exchange
For dim 6 operators arising from lepto-quark exchange the dominant decaymode is p e+0 and is predicted to have a lifetime5
p(p 0e+) =Cp 1.6 10
36yrs( MX
2 1016GeV)4 (1)
whereCp is model dependent but O(1).
In D-branes (Klebanov-Witten) the decay lifetime is
st(p e+0) =GUT(p e
+0)CstM4GM4X
whereCst is the string enhancement factor and estimates give
Cst = 0.5 1.2. The dominant process is p e+
L 0
while the decayp e
+R
0 is suppressed.
The current experimental limit is
st(p e+0) >1.4 1034yrs.
5p lifetime is sensitive to fermion mixing: P. Fileviez Perez,PLB595, 476(2004).
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
7/35
(p e+0) could be much shorter than 1036 yr.
The lifetime of the proton in higher dimensional theories could be very different
than in 4D theories Thus compactification of higher dimensional theories givesrise to Kaluza -Klein modes whose inclusion can reduce the effective scale thatenters in p decay. This is the case for 5D orbifold GUTs6.
A similar situation occures for compactification of D=6 theory where
1
M2
Xeff
4M2
c ln(M
MC
) + 2.3 .Choosing Mc MG 2 10
16 GeV, and M 1017 GeV, leads to7
(p e+0) 1 1035yr.
Certain classes of GUT models also lead to a shorter lifetime for p e+0 8
Proton decay is sensitive to extra matter which can modify the p e+0
prediction9.
6S Rabys talk
7See. e.g., Buchmuller, Covi, Emmanuel-Costa, Wiesenfeldt, hep-ph/0407070
8Babu, Pati, Tavarkiladze, JHEP 1006 (2010) 084 + Babus talk
9 Hisano, Kobayashi, Nagata, Phys.Lett. B716 (2012) 406-412, arXiv:1204.6274[hep-ph].
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
8/35
-
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
9/35
Brief intro to SUSY
SUSY is an extension of the space time symmetry. It isprimarily a high scale symmetry.
SUSY was discovered in the early seventies 10
However, SUSY is a global symmetry and difficult to break ina phenomenologically viable fashion.
Gauging of SUSY brings in gravity 11 and leads tosupergravity12.
10P Ramond, PRD 3, 2415 (1971); Y.A. Golfand and E. Likhtman, JETPLett. 13, 323 (1971); D.V. Volkov and V.P. Akulov, PLB 46, 109 (1973); J.
Wess and B.Zumino, PLB 49, 52 (1974).
11PN, R. Arnowitt, Phys.Lett. B56, 177 (1975)R. Arnowitt, PN, B. Zumino, Phys.Lett. B56, 81 (1975).
12D Z Freedman, P. van Nieuwenhuizen, S. Ferrara, Phys.Rev. D13 (1976)
3214-3218.
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
10/35
SUGRA Unification, SUSY scale, proton decay
For the rest of the talk we will focus on SUGRA unification, the scale of SUSY andthe proton decay in light of the LHC data.
Supergravity grand unification (SUGRA) breaks SUSY via gravity mediation. 13It depends on three arbitrary functions
K(z, z), W(z), f
Under simplifying assumptions on K and f the parameter space is11, 14
m0, m1/2, A0, B0, 0. Under radiative breaking of the electroweak symmetry
one can redefine the parameter space of the universal SUGRA models
m0, m1/2, A0, tan , sign().
There are other possibilities for breaking of SUSY
Gauge mediation 15
Anomaly mediation 1613A H Chamseddine, R. Arnowitt, PN, Phys.Rev.Lett. 49 (1982) 970.14L. J. Hall, J. D. Lykken and S. Weinberg, Phys. Rev. D 27, 2359 (1983).15M. Dine, A. E. Nelson, Phys. Rev. D48, 1277 (1993); Further work: Nir,
Shirman, .16L. Randall and R. Sundrum, Nucl. Phys. B 557, 79 (1999); G. F. Giudice,
M. A. Luty, H. Murayama and R. Rattazzi, JHEP 9812, 027(1998).
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
11/35
SUGRA, strings, branes
Low energy limit of string models and of brane models is N = 1
supergravity. Thus supergravity models encompass a broad class,the various models being discriminated by the choices of the Kahlerpotential, the superpotential and the gauge kinetic energy function.
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
12/35
The LHC constraints on the sugra models with universalboundary conditions
http://find/http://goback/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
13/35
[GeV]0m
500 1000 1500 2000 2500 3000
[G
eV]
1/2
m
100
200
300
400
500
600
700
800900
1000
l~LEP2
1
LEP2
NoEW
SB
=LSP
Non-Conv
ergentR
GE's
)=500g~m(
)=1000g~m(
)=1500g~m(
)=2000g~m(
)=1000
q~m(
)=1500
q~m(
)=2000
q~m(
)=
2500
q~m(
Median Expected Limit1Expected Limit
Observed Limit(theory)1Observed
HAD Observed LimitLeptons Observed Limit
-1L dt = 4.7 fb= 7 TeVsCMS
Hybrid CLs 95% C.L. Limits
Razor Inclusive
NoEW
SBNon-C
onverge
ntRGE'
s
)=10tan(
= 0 GeV0A> 0= 173.2 GeVtm
=LSP
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
14/35
Natural SUSY and proton stability
Some versions of the so called natural SUSY advocate a stop mass in the very lowmass region which was not yet eliminated by experiment. However, proton stabilitydoes not favor this region.
.
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
15/35
Higgs boson discovery
ATLAS and CMS Collaborations have measured the mass of anew boson which lies between 125 and 126 GeV17. Whilemany properties of the new boson need still to be identified itis the general belief that the particle seen is the Higgs bosonwhich enters in the electroweak symmetry breaking
It is quite remarkable that the observed Higgs boson mass liesclose to the upper limit predicted in grand unified supergravitymodels which is roughly 130 GeV 18,19,20.
17CMS Collaboration, Phys. Lett. B, 716, (2012) 3061,arXiv:1207.7235ATLAS Collaboration, Phys. Lett. B, 716 (2012) 129. arXiv:1207.7214.
18S. Akula, B. Altunkaynak, D. Feldman, PN and G. Peim, PRD 85, 075001 (2012).19A. Arbey, M. Battaglia, A. Djouadi and F. Mahmoudi, JHEP 1209 (2012) 107,
arXiv:1207.1348 [hep-ph].20O. Buchmueller, R. Cavanaugh, A. De Roeck et al. Eur. Phys. J. C 72 (2012)
2020,arXiv:1112.3564.
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
16/35
A comparison of mSUGRA, mGMSB, mAMSB and others
A. Arbey, M. Battaglia, A. Djouadi and F. Mahmoudi, JHEP 1209 (2012) 107,arXiv:1207.1348 [hep-ph].
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
17/35
No-scale: m0 A0 0
cNMSSM: m0 0, A0 14 m1/2
VCMSSM: A0m0
NUHM: mSUGRA + two more inputs.
A. Arbeya, M. Battaglia, A. Djouadi, F. Mahmoudi and J. Quevillon, Phys.Lett.
B708 (2012) 162-169, arXiv:1112.3028.
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
18/35
Implications of the 125 GeV Higgs boson
SM: Within the standard model the Higgs is a bit too light.
SUSY: Within SUSY the Higgs is a bit too heavy.
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
19/35
125 GeV Higgs boson in SM
In the Standard Model vacuum stability puts a stringent constraint on the allowed
range of the Higgs mass.With the inclusion of both the theoretical error in the evaluation ofmhestimated at 1.0 GeV and the experimental errors on the top mass and sthe analysis 21
mh >129.4 1.8 GeV,
for the standard model to have vacuum stability up to the Planck scale. Thisexcludes the vacuum stability for the SM for mh0 < 126 GeV at the 2 level.
The Higgs mass of 125 GeV would give vacuum stability up to only scalesbetween 109 1010 GeV and stability up to the Planck scale would requirenew physics.
Vacuum stability is less problematic in supersymmetric theories22
21Degrassi, Di Vita, Elias-Miro, Espinosa, Giudice et al. JHEP, 1208, 098 (2012).22J. Hisano and S. Sugiyama, Phys.Lett. B696, 92 (2011), arXiv:1011.0260
[hep-ph]; Carena, S. Gori, I. Low, N. R. Shah and C. E. Wagner, JHEP 1302, 114(2013); T. Kitahara, JHEP 1211, 021 (2012), arXiv:1208.4792 [hep-ph].
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
20/35
A Higgs mass 125 GeV implies a high SUSY scale
In MSSM the Higgs boson mass obeys at the tree level
mh < MZ
and a large loop correction is needed to pull it up to the experimental value.
The dominant one loop contribution arises from the top/stop sector and is givenby
m2h 3m4t22v2
lnM2Sm2t
+ 3m4t22v2
X2tM2S
X4t12M4S
+ .
v = 246 GeV (v is the Higgs VEV), MS is an average stop mass, andXt At cot .
An mh 125GeV implies MS in the several TeV region.
The large SUSY scale tends to stabilize p decay from B&L violatingdimension five operators.
P t d i t i l t Hi i h K+ d
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
21/35
Proton decay via triplet Higgsino exchange: p K+ mode
Operators arising from triplet Higgsino exchange must be dressed by charginos,neutralinos and gluino exchanges to produce B&L violating dim 6 operators. All thesedressings have been computed fully23. The dim 5 proton decay has a significant modeldependence. Both high energy and low energy physics affect this decay24. There is a
rich literature on dim 5 decay 25
Dressing loop diagrams for p K+ decay from dimension five operators via exchange of charginos, squarks
and Higgsino color triplets.
Very crudely
(p K+) C(m4q/m2
tan
2 )
Formq in the sub TeV region, this could lead to too short a lifetime for this mode. This is specifically the case fornatural models which advocate Ms 300 500GeV.
23Arnowitt, Chamseddine, PN; Hisano, Murayama, Yanagida; Lucas, Raby; Goto, Nihei
24See, e.g., PN, P Fileviez Perez, Phys. Report, Vol. 441, No.5-6,(2007).
25Weinberg; Sakai, Yanagida; Dimopoulos, Raby Wilczek; Ellis, Nanopoulos, Rudaz; Arnowitt, PN; Babu,
Pati, Wilczek; Bajc, Fileviez Perez, Senjanovic; Dosner; Dermisek, Mafi, Raby;Emmanuel-Costa, Wiesenfeldt;
Dutta, Mimura, Mohapatra; Syed, PN; Babu, Pati, Tavartkiladze, .
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
22/35
Suppression ofp K+ by cancellation
A suppression ofp K+ decay mode can arise by cancellations26 amongvarious contributions to dimension five operators.
An example of this occurs from operators arising from a new class ofSO(10)models where the Higgs structure at the GUT scale is of the form 27
144 + 144.
In SU(5) U(1) decomposition ofSO(10), 144 + 144 has higgsino tripletscoming from 5(3) +5(3)and 45(3) + 45(3) and the cancellation occursamong contributions arising from these.
In this class of models the SO(10) GUT symmetry breaks to the SM gaugegroup at one scale and one does not need different Higgs representations for
rank reduction and for a complete breaking of the GUT symmetry.
26PN, R. M. Syed, Phys. Rev. D 77, 015015 (2008) [arXiv:0707.1332 [hep-ph]].27K. S. Babu, I. Gogoladze, PN, R. M. Syed, Phys. Rev. D 72, 095011 (2005)
[hep-ph/0506312]; Phys. Rev. D 74, 075004 (2006) [hep-ph/0607244].
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
23/35
Implications of the high Higgs mass for proton stabilityMengxi Liu, PN: arXiv:1303.7472
Higgs boson mass mh0 (GeV)
ProtonLife
time(yrs)
115 120 125 1301033
1034
1035
1036
Curve 1Curve 2Curve 3Experiment(Lower Limit)
A 5-10 GeV shift in the Higgs boson mass can result in a shift in the proton decay life time for the mode K+
by up to 2 orders of magnitude.
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
24/35
exp(p K+) constraint on the SUGRA parameter spaceMengxi Liu, PN: arXiv:1303.7472
m0 (TeV)
Lifetime(yrs)
0 5 10 15 20 25 3010
30
1035
1040
Experiment(Lower Limit)
p K+ lifetime constraint on mSUGRA/CMSSM (left panel) and on non-universal SUGRA model with
gaugino mass non-universalities (right panel) where MeffH3 /MG = 50.
The discovery ofp K+ mode could occur even with a modest increase insensitivity.
28
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
25/35
Projected sensitivities of Hyper-K28
1032
1033
1034
1035
1036
1037
10-2
10-1
1 10 102
103
Exposure (Megaton year)
PartialLifetime(years)
pK+sensitivity
with 20%coverage (90%CL)
Super-K limit
206ktyr
3.9 x 1033
yrs (90%CL)
Sensitivities of the Hyper-Kamiokande proton decay search as a function of detector exposure. Left Panel: for
p e+0 mode; Right Panel: for p K+ mode.
MICA point taken from talk by Elisa Resconi (TU Munich): Aspen Winter Workshop -New Directions in NeutrinoPhysics. http://indico.cern.ch/conferenceDisplay.py?confId=224351
28K. Abe, T. Abe, H. Aihara, Y. Fukuda, Y. Hayato, K. Huang, A. K. Ichikawa and M. Ikeda et al., Letter of
Intent: The Hyper-Kamiokande Experiment Detector Design and PhysicsPotential, arXiv:1109.3262
[hep-ex].
C fli i id f l
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
26/35
Conflicting evidence from muon anomalous moment
The Brookhaven experiment E821 29 which measures a = 1
2(g 2) shows
a deviation from the Standard Model prediction 30 at the 3 level.
a = (287 80.) 1011 . (2)
The SUSY contribution31 arises from and 01 loops.
A rough estimate of the supersymmetric correction is
a sign()
130 1011100GeV
MSUSY
2tan . (3)
In order to obtain a SUSY correction of size indicated by the Brookhaven
experiment masses of sparticles in the loops, i.e., the masses of, , 01,must be only about a few hundred GeV.
29Muon G-2 Collaboration, Phys. Rev. D 73 (2006) 072003
30K. Hagiwara, R. Liao, A. D. Martin et al. J. Phys. G, 38 (2011) 085003, M. Davier, A. Hoecker,
B. Malaescu et al. Eur. Phys. J. C, 71 (2011) 1515.31
T. Yuan, R. L. Arnowitt, A. H. Chamseddine, P.N., Z. Phys. C, 26 (1984) 407; D. A. Kosower, L. M.Krauss, and N. Sakai, Phys. Lett. B 133 (1983) 305; S. Heinemeyer, D. Sto ckinger,andG.Weiglein, Nucl. Phys.
B 690 (2004) 62 -80.
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
27/35
SUGRA unification with unconventional boundary conditions at high scale
As mentioned the experimental evidence points to color particles being much heavier than the uncolored particles.Thus we specify the boundary conditions for soft parameters by 32
m0, m3, A0, tan , sign()
while m1 = m2 > m0. Therenormalization group evolution of squarks is dominated by the gluino mass.
d
dt
m2H2m2Um2Q
= Yt
3 3 32 2 21 1 1
m2H2m2Um2Q
YtA2t
321
+
32m22 + 1m
21
163
3m23 +
169
1m21
163 3m
23 + 32m
22 +
19 1m
21
.
32S. Akula and PN., Gluino-driven Radiative Breaking, Higgs Boson Mass,Muon g 2,andtheHiggs
Diphoton Decay in SUGRA Unification, arXiv:1304.5526 [hep-ph].
S lit l SUSY t f SUGRA
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
28/35
Split scale SUSY spectrum for gSUGRA.
105
1010
1015
102
10
3
104
RGE Scale Q (GeV)
Mass(GeV)
H1
H2
q
M1M2
M3
m0
m1/2
m20+
21/2
S. Akula and PN., arXiv:1304.5526 [hep-ph].
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
29/35
Light and heavy spectrum of Split Scale SUSY
Particles with light masses
33
01, 02,
1, 1, 2, l
Particles with heavy masses
03, 04,
2, H
0, A0, H, q, g
An observation of the p K+ mode is possible inimproved p decay experiment in this Split Scale SUSYmodel.This is in contrast to split SUSY case.
33As a comparison the light spectrum of split susy (Arkani-Hamed, Dimopoulos,
JHEP 0506, 073 (2005)) consists of light Higgsinos
Hu,d,
B,
W, g and one Higgs
doublet but does not have light sfermions.
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
30/35
A high scale solution
Mas
s
GeV
21
101
Posterior Mean
1 Credible Interval
2 Credible Interval
200
400
600
800
1000
12
Mas
s
TeV
gqt1
2H0
Posterior Mean
1 Credible Interval
2 Credible Interval
5
10
15
20
Figure: Split scale SUSY spectrum for gSUGRA.
Implications of LHC13 for the supersymmetric decay of the
http://goforward/http://find/http://goback/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
31/35
Implications of LHC13 for the supersymmetric decay of theproton
We have already seen that the measurement of the Higgs
boson mass has led to our revision of the proton decaylifetime predictions. LHC13 would put further severeconstraints on the SUGRA parameter space (see the exclusionplot in m0 m1/2 at LHC13.)The observation of sparticles, specifically squarks at the LHC
would give a strong hint that supersymmetric decay of theproton should be seen. The observation of some of thesparticles should allow us to estimate values ofm0, m1/2, A0, tan .
These estimates would allow us to make much more precisepredictions on the proton lifetime arising from dimension fiveoperators.
Thus there are strong direct implications of LHC13 forthe observation of SUSY decays oftheproton.
Projected discovery reach in m0 m1/2 at
s = 14 TeV
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
32/35
Projected discovery reach in m0 m1/2 at
s = 14 TeVfor mSUGRA
(GeV)0m0 1000 2000 3000 4000 5000 6000 7000 8000
(G
eV)
1/2
m
400
600
800
1000
1200
1400
1600
1800
2000
=4TeV
q~m
=6TeV
q~
m
=2TeVq~
m
=2TeVg~m
=1.2TeVg~m
=3TeVg~m
=4TeVg~m=1 2 3 Ge V
h
m
=127
GeV
hm
-13000 fb
-11000 fb
-1300 fb
-1100 fb
LHC7excluded
= 172.6 GeV
t
> 0, m!= 10,, tan0
= -2m0A LHC14
From H. Baer, V. Barger, A. Lessa and X. Tata, Phys.Rev. D86 (2012) 117701,
arXiv:1207.4846 [hep-ph].
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
33/35
Conclusion
Search for proton decay is central to understanding the nature of fundamental physics.It will do many things
Provide test of quark-lepton unification.
Probe length scales ofO(1033) m which are inaccessible to any otherexperiment.
Provide a test of supersymmetry.
Opens a window to observing possible effects of strings and branes and of extradimensions.
Could throw light on the possible origin of matter generations.
In summary there are overwhelming theoretical reasonsfor making a strong push for proton decay searches.
What about fine tuning?
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
34/35
g
Fine tuning is a rather subjective issue and it depends on how you define fine tuning and also depends on whatphenomena are included in fine tuning. Generally, one considers just REWSB. But one should also incude otherphonomena such as FCNC, CP and proton decay. Here we consider REWSB and proton decay.
REWSB: Fine tuning in REWSB arises from the equation that determines the Z -boson mass
1
2M2Z =
2 + |mHu |2 +
If or |mHu | get too large, one needs a fine tuning to get the Zmass. An obvious ways to definedefine fine tuning in REWSB is
F2|mHu |
2
M2Z
Low soft masses are then preferred as large soft masses appear to lead to a large fine tuning.
Proton decay: Here we define fine tuning as
Fpd =4 1033yr
(p K+)yr. (4)
A more appropriate object to consider then is
F =
ni=i
Fi
1n
. (5)
In this circumstance a smaller fine tuning occurs at large m0.
http://find/ -
8/12/2019 Proton Decay in SUSY GUT in Light of LHC
35/35
Fine tunings with inclusion of p decayMengxi Liu, PN: arXiv:1303.7472
m0 (TeV)
FineTuning
0 5 10 15 20 25 3010
4
102
10
0
102
104
106
F
FpdF
Top left: Fine tuning constraint from REWSB and from proton stability for the mode p K+
and the meanas a function ofm0 for mSUGRA. Right: A smooth curve through the averages34.
The combined fine tuning appears to favor larger m0.
34The analysis is similar in spirit to a recent work (Jaeckel, Khoze, arXiv:1205.7091 [hep-ph])where FCNC
and CP violation were included along with REWSB in the analysis of fine tuning.
http://find/