Pure Gravity Mediation with m3/2= 10–100TeV
Masahiro Ibe(a,b), Shigeki Matsumoto(b), and Tsutomu T. Yanagida(b)
(a)ICRR, University of Tokyo, Kashiwa, 277-8582, Japan
(b)IPMU, TODIAS, University of Tokyo, Kashiwa, 277-8583, Japan
Recently, the ATLAS and CMS collaborations reported exciting hints of a
Standard Model-like Higgs boson with a mass around 125GeV. Such a Higgs
boson mass can be easily obtained in the minimal supersymmetric Standard
Model based on the “pure gravity mediation model” where the sfermion masses
and the Higgs mass parameters are in tens to hundreds TeV range while the
gauginos are in the hundreds GeV to TeV range. In this paper, we discuss
detalis of the gaugino mass spectrum in the pure gravity mediation model. We
also discuss the signals of the model at the current and future experiments such
as cosmic ray observations and the LHC experiments. In particular, we show
that the parameter space which is consistent with the thermal leptogenesis
can be fully surveyed experimentally in the foreseeable future.
arXiv:1202.2253v1 [hep-ph] 10 Feb 2012
The pure gravity mediation model investigated in Ref. is a surprisingly simple
model of the supersymmetric Standard Model (SSM). There, the scalar bosons obtain
supersymmetry (SUSY) breaking masses from a SUSY breaking sector via tree-level
interactions in supergravity. The Higgs mixing mass parameters, µ-term and B-
term, are also generated via tree-level interactions of supergravity. Due to the
tree-level mediation, the scalar boson masses and the Higgs mixing mass parameters
are expected to be of the order of the gravitino mass, m3/2. The gaugino masses are,
on the other hand, generated at the one-loop level[4, 5, 6]. Thus, the pure gravity
mediation model predicts a hierarchical spectrum. The greatest benefit of the pure
gravity mediation is that the model requires no additional fields to realize the above
spectrum. Therefore, the pure gravity mediation model is the bare-bones model of
the supersymmetric Standard Model.
The pure gravity mediation model is particularly successful when the gravitino
mass is in the range of m3/2= 10–100TeV. The first advantage is the alleviation
of the cosmological gravitino problem[7, 8]. Especially, the model does not suffer
from the gravitino problem even for a very high reheating temperature after inflation,
TR?√3×109GeV, which is essential for the successful thermal leptogenesis. The
second advantage is that the model has a good candidate for dark matter. For the
above gravitino mass range, the lightest superparticle (LSP) which is neutral wino
in the pure gravity mediation obtains a mass in hundreds GeV to TeV range. The
neutral wino in this mass range is a good candidate of weakly interacting particle
dark matter[10, 11]. Moreover, as emphasized in Ref.[12, 1], the relic density of the
neutral wino can be consistent with the observed value when we assume the thermal
leptogenesis. Therefore, the pure gravity mediation model goes quite well with the
thermal leptogenesis. Another but an important advantage in cosmology is that the
model does not suffer from the cosmological Polonyi problem since no singlet
SUSY breaking fields are required in the model.1In addition to those advantages
in cosmology, the problems of flavor-changing neutral currents and CP violation in
the SSM are highly ameliorated thanks to the large masses for squarks and sleptons.
The unification of the gauge coupling constants at the very high energy scale also
provides a strong motivation to the model.2
1See also Ref. for the Polonyi problem in dynamical supersymmetry breaking models.
2In fact, the gauge coupling constants unify at around 1016GeV at a few percent level even for
In Ref., two of the authors (M.I. and T.T.Y) discussed the lightest Higgs boson
mass of the minimal SSM (MSSM) based on the pure gravity mediation model.
There, we showed that the lightest Higgs boson mass is required to be below about
128GeV if we assume the thermal leptogenesis. This requirement has been shown to
be consistent with the most recent experimental constraints on the Higgs boson mass,
mh> 115.5GeV and mh< 127GeV at 95%C.L. reported by ATLAS and CMS
collaborations. Furthermore, as shown in Ref., the pure gravity mediation
model can easily explain the rather heavy Higgs boson mass around 125GeV which
is tantalizingly hinted by ATLAS and CMS collaborations.
In this letter, we discuss phenomenological, cosmological and astrophysical as-
pects of the pure gravity mediation model. In particular, in this paper, we concen-
trate ourselves on the the parameter space of the model which is consistent with the
thermal leptogenesis. As we will show, such a parameter space can be fully tested by
the observation of the cosmic rays, especially by the observation of the anti-proton
flux in the foreseeable future. We also discuss the strategies of the discoveries and
the measurements of the gauginos at the Large Hadron Collider (LHC) experiments.
There, the distinctive gaugino mass spectrum in the pure gravity mediation model
plays important roles.
The organization of the paper is as follows. In section2, we review the model with
pure gravity mediation. There, we discuss the details of the gaugino spectrum. In
section3, we discuss the phenomenological, cosmological and astrophysical aspects
on the model. The final section is devoted to our conclusions.
2 Pure gravity mediation model
In the pure gravity mediation model, the only new ingredient other than the MSSM
fields is a (dynamical) SUSY breaking sector. There, the scalar bosons obtain the soft
SUSY breaking squared masses mediated by tree-level interactions in supergravity.
With a generic K¨ ahler potential, all the soft squared masses of the scalar bosons are
a rather large µ-term of 10–100TeV. It should be noted that the scale of the coupling unification
is slightly lower than the conventional SSM for m3/2= 10–100TeV about a factor of two or so.
Thus, the model predicts a slightly shorter proton lifetime via the so-called dimension six operators,
τp? 1035yrs, which is within the reach of the Hyper-Kamiokande Experiment.
expected to be of the order of the gravitino mass. The soft SUSY breaking scalar
trilinear coupling, the A-terms, are, on the other hand, expected to be suppressed
in supergravity at the tree-level.
In the pure gravity mediation model, the Higgs mixing µ and B parameters can
be also generated via tree-level interactions in supergravity. In fact, if the Higgs
doublets are not charged under any special symmetries, we expect the following
K¨ ahler potential,
K ? cHuHd+
X†XHuHd+ h.c.. (1)
Here, X denotes a chiral SUSY breaking field in a (dynamical) SUSY breaking sector,
MPLis the reduced Planck scale, and c and c?are coefficients of O(1). Through the
above K¨ ahler potential, the µ- and the B-parameters[3, 18]
= cm3/2, (2)
where FXis the vacuum expectation value of the F-component of X. Therefore, the
µ- and B Higgs mixing parameters are also expected to be of O(m3/2).3
For the gaugino masses, on the other hand, tree-level contributions in the super-
gravity are extremely suppressed since we have no SUSY breaking fields which are
singlet under any symmetries. At the one-loop level, however, the gaugino masses are
generated without having singlet SUSY breaking fields, which is called the anomaly
mediated contributions[4, 5]. Besides, the gauginos also obtain contributions from
the heavy Higgsino threshold effects at the one-loop level. Putting these one-loop
contributions together, the gaugino masses at the energy scale of the scalar boson
masses, MSUSY= O(m3/2), are given by[4, 10]
M3 = −3(6)
Here, the subscripts Ma, (a = 1,2,3) correspond to the gauge groups of the Standard
Model U(1)Y, SU(2)Land SU(3), respectively. In the above expressions, the terms
3If the SUSY breaking sector has a singlet Polonyi field, the so-called Giudice-Masiero mecha-
nism can also generate the µ and B Higgs mixing parameters of O(m3/2). In that case, however,
the model suffers from the Polonyi problem.
proportional to m3/2denote the anomaly mediated contributions and the terms pro-
portional to L denote the Higgsino threshold contributions. The parameter L is
L ≡ µHsin2β
where mAdenotes the mass of the heavy Higgs bosons, and tanβ is the ratio of the
vacuum expectation values of the up-type Higgs boson Huand the down-type Higgs
boson Hd. As we will see in the next subsection, the size of L is expected to be of
the order of the gravitino mass in the pure gravity mediation model. Therefore,
the wino mass obtains comparable contributions from the anomaly mediated effects
and the Higgsino threshold effects. This facts have a great impacts on the testability
of the pure gravity mediation model at the LHC experiments.
Before closing this section, we should emphasize the difference of the pure gravity
mediation model from the the Split Supersymmetry[20, 21, 22]. In the first place, the
Split Supersymmetry mainly considers a scalar mass scales much higher than that
in the pure gravity mediation model, i.e. MSUSY? 104−6GeV. Thus, the anomaly-
mediated gaugino masses should be suppressed in the Split Supersymmetry, while
we rely on the anomaly-mediated gaugino masses in the pure gravity mediation
Thus, the pure gravity mediation model is more close to the PeV-scale
Supersymmetry and the Spread Supersymmetry. Another important and
more practical difference is the size of µ-term. In the Split Supersymmetry, it is
assumed that the higgsinos are also in the TeV range. Thus, the absence of the
Higgsino in the TeV range will be a crucial observation to distinguish the pure
gravity mediation model from the Split Supersymmetry. Furthermore, as we will see
below, such a large µ-term leads to a peculiar gaugino spectrum in the pure gravity
mediation model. Thus, we can also distinguish these models by carefully examining
the gaugino mass spectrum.
2.2 Details on gaugino masses
As discussed above, the pure gravity mediation model predicts that the sfermions,
Higgsinos and the heavier Higgs bosons in the MSSM have masses of the order of the
gravitino mass, m3/2= 10–100TeV. Therefore, the only accessible particles at the
collider experiments in the foreseeable future are the gauginos. In this subsection, we
4See discussions on the possible cancellation of the anomaly-mediated gaugino masses[22, 23].
tanΒ ? O?1?
0 50 100150200250 300
tanΒ ? O?1?
0 50100 150200250 300
tanΒ ? O?1?
Figure 1: The anomaly mediated contributions to the gaugino masses (denoted by AMSB).
The each line corresponds to the heavy scalar threshold scale MSUSY = 10,100 and
1000TeV from bottom to up. In the figure, we have taken µH= O(m3/2) and tanβ = O(1),
although they are not sensitive to those parameters.
give detailed analysis on the gaugino mass spectrum in the pure gravity mediation
First, let us consider the anomaly mediated contributions to the gaugino masses.
As we see from Eqs.(4)-(6), the wino is the lightest gauginos for L = 0.This
feature is related to the fact that the SU(2)Lgauge coupling constant is the least
scale dependent out of the three gauge coupling constants. In Fig.1, we show the
anomaly mediated gaugino masses as a function of the gravitino mass. The figure
shows that the gaugino masses are roughly given by,
mbino ? 10−2m3/2,
mwino ? 3 × 10−3m3/2,
mgluino ? (2 − 3) × 10−2m3/2.
with small dependences on the heavy scalar threshold scale, MSUSY. Thus, for the
wino mass mwino= 300GeV, for example, the gluino mass is heavier than 2TeV if
the anomaly mediated contributions dominate the gaugino masses.
Now, let us estimate the typical size of L in the pure gravity mediation model
which parametrize the Higgsino threshold contributions to the gaugino masses. Let
us remember that we require one of the linear combinations of the two Higgs bosons,
h = sinβHu−cosβH∗
ing. In terms of the Higgs mass parameters, the above fine-tuning condition requires,
dremains very light for successful electroweak symmetry break-
Hd) − (BµH)2? 0 ,(11)
while the Higgs mixing angle is related to the Higgs mass parameters by,
Hd+ 2|µH|2) .(12)
0.0 0.51.0 1.52.0 2.53.0
Figure 2: The typical values of |L/m3/2| for tanβ = 1,3,10 and 30. The unit of the
vertical axis is arbitrary. We have distributed µHand B from m3/2/3 to 3m3/2and required
in Eqs.(11) and (12). The ratios of the areas of each histogram roughly represent the
3/2| < 5 which are determined by the electroweak symmetry breaking conditions
relative consistency of the value of tanβ in the pure gravity mediation.
Hu,ddenote the soft SUSY breaking squared masses of the two Higgs doublets,
Huand Hd. These conditions show that the mixing angle β is expected to be of O(1),
since all the mass parameters of the Higgs sector (except for a fine-tuning condition)
are of the order of the gravitino mass in the pure gravity mediation model.5
By putting the typical values of tanβ = O(1) and the Higgs mass parameters of
the gravitino mass scale together into the definition of L in Eq.(7), we find that the
typical value of L is also of the gravitino mass scale. To see this clearly, we show
the typical size of L for tanβ = 1,3,10 and 30 (Fig.2). Here, we have assumed
that µH and B range from m3/2/3 to 3m3/2, respectively.6The figure also shows
that |L/m3/2| ? 0.5 − 2 for tanβ = O(1). Therefore, in the pure gravity mediation
model, we expect L/m3/2= O(1), which leads to comparable contribution to the
wino mass from the Higgsino threshold effects (see Eq.(5)).
In Fig.3, we show the ratio of the wino and bino masses with and without the
5Hereafter, we use a phase convention where BµHis real and positive.
6More precisely, we assumed that log10µH/m3/2and log10B/m3/2obey the normal distribution
with the mean value 0 and the standard deviation 0.5×log103. For a given tanβ, the Higgs squared
masses are determined by m2
number of random numbers for each tanβ. Afterward, we required |m2
are of the order of the gravitino mass. Thus, the ratios of the areas of each histogram roughly
H| + BµHcotβ(−1). In the figure, we generated the fixed
3/2| < 5 so that they
represent the relative consistency of the value of tanβ in the pure gravity mediation. The figure
shows that the model with tanβ = O(10) is less consistent as expected.
Figure 3: (Left) The ratios of the wino and bino masses with and without the Higgsino
contributions for given values of L. We have used a phase convention that m3/2is real
and positive. The red lines show the |L| dependences for given phases of L, while the blue
lines show the arg[L] dependences for given values of |L|. (The dashed blue lines show the
values of |L| in between the ones for the two solid lines.). In the gray shaded region for
|L/m3/2| ? 3, the wino is no more the LSP. (Right) The L dependences of the gaugino
masses for m3/2= MSUSY= 50TeV for L > 0(arg[L] = 0) and L < 0(arg[L] = π).
Higgsino contributions for given values of L (left panel). The figure shows that the
wino mass can be about twice as heavy as the anomaly mediated contribution for
|L/m3/2| ? 1 which is expected in the pure gravity mediation model. It should be
noted that the wino becomes no more the LSP where the Higgsino threshold contri-
bution dominates. In such cases, the relic density of dark matter easily exceed the
observed one due to the highly suppressed annihilation cross section of the bino for
O(100)GeV. Fortunately, however, the figure shows that the bino becomes LSP only
for |L/m3/2| > 3 which is less likely in the pure gravity mediation model. Therefore,
in the pure gravity mediation model, the LSP is mostly wino-like, although the wino
mass obtains a comparable contribution from the Higgsino threshold effects.7
In Fig.4, we show the contour plot of the wino mass. In the figure, the blue shaded
region shows the current experimental constraints on the wino mass mwino≥ 88GeV
7In general, a relative phase between L and m3/2is a free parameter, and hence, the three
gauginos have different phases. Such gaugino phases, however, do not cause serious CP-problems,
since the Higgsinos as well as the sfermions are expected to be very heavy in the pure gravity
mediation model. Interestingly, the relative phase of O(1) may lead to the visible electron electric
dipole moment of de/e ∼ 10−30cm for the µ-term in the tens to hundreds TeV range, which
can be reached in future experiments.
LEP2 Wino constraint
ATLAS Gluino constraint
The contour plot of the wino mass for L > 0 and L < 0.Here, we
have taken MSUSY = m3/2(blue lines).
mwino ≥ 88GeV for the degenerated neutralino-chargino obtained by LEPII experi-
ment. The orange shaded region denotes the experimental constrain on the gauginos,
mgluino? 750GeV for mLSP< 200GeV reported by the ATLAS collaboration.
(The dashed lines corresponds to mwino =
The blue shaded region denotes the experimental constraint,
for the degenerated neutralino-chargino obtained gz by LEPII experiment. The
orange shaded region shows the experimental constrain on the gauginos, mgluino?
750GeV for mLSP? 200GeV reported by the ATLAS collaboration. By remem-
bering that L/m3/2? 2.5 is less likely in the pure gravity mediation, the figure shows
that the gluino mass bound requires m3/2? 30TeV.8
Finally, we discuss the lightest Higgs boson mass in the pure gravity mediation
model. In the pure gravity mediation model, the lightest Higgs boson mass is ex-
pected to be heavier than the conventional MSSM models due to the heavy scalar
bosons. In Fig.5, we show the Higgs boson mass obtained by solving the full
one-loop renormalization-group equations of the Higgs quartic coupling and other
coupling constants given in Ref. with the boundary condition,
at the heavy scalar scale. The threshold corrections at the heavy scalar scale are also
taken into account. We also take into account the weak scale threshold corrections
8Fig.2 shows that L/m3/2? 2.5 is possible for tanβ ? 1. As we will see from Fig.5, however, the
lightest Higgs boson mass of our main concern (124GeV< mh< 126GeV) requires m3/2? 100TeV
for tanβ ? 1. Thus, the conclusion m3/2? 30GeV is not changed.
Figure 5: The contour plot of the lightest Higgs boson mass. (The dashed contours are for
the intermediate values between the two solid contours.) Here, we have fixed m3/2= 50TeV
and taken µH = MSUSY. The gray shaded regions correspond to mh< 115.5GeV and
mh> 127GeV which are excluded by the ATLAS and CMS collaborations at 95%C.L.
for the central value of the top quark mass, mtop= 173.2±0.9GeV. The light gray shaded
region denotes the Higgs mass constraints including the 1σ error of the top quark mass.
The orange band shows the Higgs boson mass 124GeV < mh< 126GeV hinted by the
ATLAS and CMS collaborations for the central value of the top quark mass. The light
orange band is the one including the 1σ error of the top quark mass.
to those parameters in accordance with Ref.[30, 31]. It should be noted that the
predicted Higgs boson mass is slightly lighter than the one in Ref. for a given
(MSUSY,tanβ), since the Higgsino contributions decouple at the very high scale in
the pure gravitino mediation model (see Ref.).
In the figure, the gray shaded regions correspond to mh< 115.5GeV and mh>
127GeV which are excluded by the ATLAS and CMS collaborations[16, 17] at
95%C.L. for the central value of the top quark mass, mtop= 173.2 ± 0.9GeV.
The light gray shaded region denotes the Higgs mass constraints including the
1σ error of the top quark mass. The orange band shows the Higgs boson mass
124GeV < mh< 126GeV hinted by the ATLAS and CMS collaborations[16, 17] for
the central value of the top quark mass. The light orange band is the one including
the 1σ error of the top quark mass.
By combined with m3/2? 30TeV which is required from the experimental gluino
mass bound, the hinted Higgs boson in the Fig.5 (124GeV < mh < 126GeV)
constrains the value of tanβ to tanβ ? 7. This shows that the pure gravity mediation
works quite consistently since tanβ = O(1) is expected in the pure gravity mediation
3Signals of the pure gravity mediation model
In this section, we consider several signals predicted in the pure gravity mediation
model. Before going to discuss those, we summarize current cosmological constraints
on the model. After that, we consider signals related to dark matter detections, where
current astrophysical constraints on the dark matter mass and near-future prospects
to detect the dark matter are discussed. We finally consider collider signals with
particularly focusing on the pair production of the gluino at the LHC experiments
with the center of mass energy of 14TeV.
We first consider the thermal history of the dark matter which is the neutral wino in
the pure gravity mediation model. Its SU(2)Lpartner, the charged wino, is slightly
heavier than the neutral one by 155–170MeV because of contributions from one-
loop gauge boson diagrams. The charged wino decays into a neutral wino and
a pion with the lifetime of O(10−10)sec. It is known that the thermal relic density
of the wino, which is obtained by considering not only self-annihilation processes of
the neutral wino but also co-annihilation processes between the neutral and/or the
charged winos, can be consistent with the observed dark matter density when its
mass is mwino? 2.7TeV. This is because the annihilation cross section of the wino is
highly boosted by the non-perturbative effect called Sommerfeld-enhancement.
On the other hand, the wino dark matter is also produced non-thermally through
the late time decay of the gravitino, which also contributes to the relic abundance
of the dark matter. If the contribution is significant, the neutral wino consistent
with the observed dark matter density is much lighter than 2.7TeV[10, 11]. In
particular, in order to have an appropriate reheating temperature for the successful
thermal leptogenesis, there is an upper bound on the wino mass; mwino? 1TeV.
This fact means that the most of the dark matter observed today is not from thermal
relics but produced non-thermally by the late time decay of the gravitino.
Since the neutral wino has a large annihilation cross section into a W-boson pair,
which is of the order of 10−24–10−25cm3/s when mwino? 1TeV, it may affect several
phenomena in the early universe . For instance, the annihilation may affect
abundances of light elements, and, in fact, observations of the elements put a bound
on the mass of the neutral wino as mwino ? 200GeV in order not to destroy the
elements during Big-Bang Nucleosynthesis (BBN). The annihilation also affects
the recombination history of the universe. If the annihilation is significantly large, it
modifies the spectrum of cosmic microwave background. This fact leads to the
constraint as mwino? 200GeV, which is comparable to that from BBN.
3.2Dark matter detections
Since the µ-parameter is of the order of 10–100TeV in the pure gravity mediation
model, the effect of the mixing between wino and higgsino components on the light-
est supersymmetric particle (dark matter) is negligibly small. The scattering cross
section between the dark matter and a nucleon is then estimated to be 10−47cm2,
which seems to be very challenging to discover the dark matter in on-going direct
detection experiments. This is a sharp contrast to the cases of Split Supersymme-
try model and conventional anomaly mediation models. Since the µ-parameter does
not have to be huge in these models, the tree-level diagram that the higgs boson is
exchanged in the t-channel contributes to the scattering cross section significantly,
which enables us to detect the dark matter in near future. Direct detection ex-
periments of dark matter can be therefore used as a test of the pure gravity mediation
On the contrary to the direct detection of dark matter, we can expect rich signals
at indirect detection experiments, because the dark matter is almost purely wino in
the pure gravity mediation model and its annihilation cross section is boosted by
the Sommerfeld effect. Among several on-going experiments, the most stringent
constraint on the dark matter is obtained by the Fermi-LAT experiment observing
gamma-rays from milky way satellites. This constraint is depicted in Fig.6 as a
solid (green) line. No astrophysical boost factor is assumed here. Theoretical predic-
tion of the neutral wino is also shown in the figure, which is obtained by calculating
its annihilation cross section involving the Sommerfeld effect at one-loop level.
Notice, however, that there may be some uncertainties on the constraint, since the
constraint is based on several assumptions such as the use of fixed dark matter profile.
According to Ref. in which those uncertainties (involving dark matter profiles)
on the gamma-ray experiment are discussed, we also show the region (green-shaded
Dark Matter Mass (GeV)
Annihilation Cross Section (cm /s)
Wino Dark Matter
Figure 6: Constraints and future prospects of indirect detection experiments of dark
matter. Theoretical prediction of the neutral wino dark matter is also shown.
one) above the constraint in order to take the uncertainties into account. It can be
seen that the neutral wino should be, at least, heavier than 300GeV.
Another interesting indirect detection is the PAMELA experiment observing the
cosmic-ray ¯ p (anti-proton) flux. Current constraint on the dark matter from the
experiment is also shown in Fig.6 as a blue-shaded region. Since the ¯ p flux depends
on how ¯ p propagates under the complicated magnetic field of our galaxy and which
dark matter profiles we adopt, the constraint has large uncertainties as can be
seen in the figure. The mass of the dark matter is, however, constrained to be
mwino? 230GeV in spite of the uncertainties. On the other hand, the observation
of the cosmic-ray ¯ p flux in near future is very hopeful. This is because the AMS-
02 experiment, which has already been started, has better sensitivity than the
PAMELA experiment and it is also expected that astrophysical uncertainties related
to the ¯ p propagation are reduced. The future sensitivity to detect the dark matter in
this experiment is also depicted in the figure as a red-shaded region with assuming
an appropriate propagation model. It can be seen that the sensitivity is much
below the prediction of the dark matter. It is also worth noting that the whole mass
range of the dark matter consistent with the thermal leptogenesis will be fully tested
by the future observation of the cosmic-ray ¯ p flux, because the annihilation cross
section of the dark matter is not suppressed because of the Sommerfeld effect. It
may be even possible to determine mwinoby observing the ¯ p spectrum.
PP gg + X
Gluino mass (TeV)
Cross section (fb)
s = 14 TeV
Gluino mass (TeV)
Wino mass (GeV)
L/m = 0 (AMSB)
L/m = 1
L/m = 2
Wino mass > Gluino mass
L/m > 2
Wino mass < 300 GeV
Current LHC bound
Figure 7: (Left panel) Cross section of the gluino pair production at the LHC experiment
with the center of mass energy of 14TeV. (Right panel) Gluino and wino masses within
the parameter region of mgluino? 3TeV. Shaded regions are not favored because of the
gluino LSP (mgluino> mwino), too large L (L/m3/2> 2), and dark matter constraints
(mwino< 300GeV). Current bound of the LHC experiment (7TeV) is also shown.
Finally, we comment on other indirect detections of dark matter. It is well known
that there is an anomaly at the cosmic-ray e+flux. Since it is difficult to account
for the anomaly by the neutral wino dark matter with the mass of 300–1000 GeV ,
it should be explained by some astrophysical activities. The observation of the e+
flux is therefore not better than that of the ¯ p flux to test the pure gravity mediation
model. The observation of the ν flux from the galactic center may give an good
opportunities to test the neutral wino dark matter, though the signal strength
depends on the dark matter profile at the center. On the other hand, the observation
of the ν flux from the sun seems to be challenging, because the flux is proportional
to the spin-dependent scattering cross section of the dark matter and it is estimated
to be as small as 10−48cm2in the pure gravity mediation model.
3.3 Collider signals
In the pure gravity mediation model, the ratio between gluino and wino masses can
be smaller than that of the conventional anomaly mediation model. The gluino may
therefore be produced at the LHC experiment even if the wino mass is constrained
to be mwino? 300GeV. On the other hand, all the sfermions as well as the higgsinos
are of the order of 10–100TeV in the model and they are never produced at the
LHC. As a result, the dominant collider signal of the model is the pair production of
the gluinos, whose production cross section is shown in Fig.7 (left panel). Once the
gluino is produced, it eventually decays into a neutral wino by emitting Standard
Model particles. It is known that, when the sfermions are much heavier than the
gluino, the radiative decay of the gluino into a gluon and a neutralino (˜ g → g˜ χ0) can
have a sizable branching fraction. In the pure gravity mediation model, however,
the µ-parameter is also as large as the sfermion masses and the branching fraction
is much suppressed. The non-observation of the radiative decay therefore enables us
to distinguish the pure gravity mediation model from other models predicting heavy
sfermions without the large µ-parameter.
Gluinos in the pure gravity mediation model therefore decay into two quarks
with a neutralino/chargino (˜ g → q¯ q?+ ˜ χ0/˜ χ±
but the charged wino, decays into a neutral wino (dark matter) by emitting a soft
i). The chargino, which is nothing
pion. On the other hand, when the neutralino is the bino, it decays through several
modes; a charged wino + a W-boson (˜B →˜ W±W∓), a neutral wino + a higgs boson
(˜B →˜ W0h), or a charged/neutral wino + two leptons (˜B →˜ Wl¯l?), whose branching
fractions depend highly on model parameters. In Fig.7 (right panel), we show the
range of gluino and wino masses within the parameter region of our interest for the
LHC experiment. It is also worth noting that, as shown in the previous section, the
bino mass is roughly given by mbino? mgluino/3 in the most parameter region. Thus,
the mass degeneracy between gluino and neutralino/chargino is not severe, which is
very attractive from the viewpoint of discovering the signal.
The most efficient mode to discover the signal of the pure gravity mediation
model is the pair production of the gluinos followed by the decay ˜ g → q¯ q?˜ χ with
q(q?) being a quark except the top quark and ˜ χ being a neutralino/chargino, so that
the signal event is composed of four jets + missing energy. The branching fraction
of the decay is about 73.4% when all squark masses are degenerated. In Fig.7
(right panel), the current bound on the (mgluino,mwino)-plane, which is obtained by
the LHC experiment with the center of mass energy of 7TeV and 1.04fb−1data,
is depicted with assuming that mwino∼ mbinoand 100% branching fraction of the
decay ˜ g → q¯ q?˜ χ. It can be seen that the region constrained by the current LHC
data has already been excluded by dark matter experiments. It has been also shown
that the gluino mass up to 1.2TeV can be discovered at the LHC experiment with
the center of mass energy of 14TeV when 10fb−1data is accumulated.
Once the signal of the pure gravity mediation model is discovered, the next
important task will be the mass determinations of gauginos. When the gluino is
about 1TeV and 100fb−1data is accumulated at the LHC experiment with the
center of mass energy of 14TeV, the mass difference between gluino and wino can be
determined with the accuracy of 5%, which is obtained by observing the endpoint of
two-jets invariant mass distribution at ”four jets + missing energy” events. The
mass difference will be determined more accurately with the use of a novel method
recently proposed in Ref., where the endpoint of so-called MT2distribution
is shown to be stable against the contamination of initial state radiations. On the
other hand, the gluino mass may be determined by observing the cross section of
the gluino pair production if the acceptance of the LHC experiment for this mode is
well understood. The wino mass is expected to be determined by observing the MT2
endpoint, because the endpoint has a kink structure at the wino mass as a function
of the test mass defining MT2. It has been also shown that the wino mass is
determined by using the charged track of˜ W±, because its decay length is estimated
to be O(10)cm. It may be even possible to measure the lifetime of˜ W±using
this method. The mass difference between bino and wino is determined only when
the branching fraction Br(˜ g → q¯ q˜B) × Br(˜B → l¯l˜ W0) is large enough.
Finally, we comment on collider signals of the pure gauge mediation model when
the gluino is heavier than a few TeV and is not accessible at the current and near
future LHC experiments. In such cases, we have to rely on the direct production
(Drell-Yan process) of charged winos associated with a quark (gluon). Associated
quark (gluon) is necessary as a trigger for recording data[18, 35]. Its cross section
is rapidly decreased with increasing the wino mass. Since the mass of the wino is
at most 1TeV for the successful leptogenesis, the high luminosity LHC experiment
(HL-LHC) may help us to discover the signal. On the other hand, if the multi-
TeV linear colliders such as ILC  or CLIC  are available, we can investigate
the properties of neutral and charged wino in details. Since the analysis strategy
for the mode e+e−→˜ W+˜ W−→˜ W0˜ W0π+π−is very similar to that for the golden
mode of dark matter detections, e+e−→ ˜ χ+˜ χ−→ ˜ χ0˜ χ0W+W−with χ0and χ±
being the dark matter and its charged partner, we can easily find the signal of
the pure gravity mediation model if π-mesons are efficiently detected.
The pure gravity mediation model is the bare bones model of the supersymmetric
Standard Model. Despite its simpleness, the model is quite successful for m3/2=
O(10 − 102)TeV; the model has a good candidate of dark matter, the gauge cou-
pling constants unify at the GUT scale very precisely, the Higgs boson mass around
125GeV can be easily accounted. In this sense, the model is superior even to the
Standard Model. The consistency with the thermal leptogenesis is also an significant
support of the model.
In this paper, we discussed details of the gaugino mass spectrum in the pure
gravity mediation model. There, we showed that the wino mass obtains comparable
contributions both from the anomaly-mediation and the Higgsino threshold effects.
As a result, the ratio between the wino LSP and the gluino masses can be as large
as around one third, which enhances the detectability of the model at the LHC
experiments. In fact, we showed that the gluino can be within the reach of the LHC
experiments even for the wino mass which satisfies the cosmological and astrophysical
constraints, mwino? 300GeV. This is a sharp contrast to the cases of the anomaly
mediated gaugino spectrum where the gluino mass is about eight to nigh times
larger than the wino mass. Utilizing this property, we discussed the strategies of the
discovery and the measurement of the model at the LHC experiments via the gluino
In this paper, we also discussed the prospects of the wino dark matter detection
via the cosmic ray observations. As a result, we found that the wino dark matter
scenario which is consistent with the thermal leptogenesis can be fully surveyed by
observing the cosmic ray anti-proton flux at the AMS-02 experiment. Therefore,
the most motivated parameter region of the pure gravity mediation model which is
consistent with the thermal leptogenesis can be tested over the next ten years or so.
This work is supported by Grant-in-Aid for Scientific research from the Ministry of
Education, Science, Sports, and Culture (MEXT), Japan, No. 22244021 (S.M. and
T.T.Y.) and No. 23740169 (S.M.), and also by World Premier International Research
Center Initiative (WPI Initiative), MEXT, Japan.
 M. Ibe and T. T. Yanagida, arXiv:1112.2462 [hep-ph].
 For a review, H. P. Nilles, Phys. Rept. 110 (1984) 1.
 K. Inoue, M. Kawasaki, M. Yamaguchi and T. Yanagida, Phys. Rev. D 45, 328
 G. F. Giudice, M. A. Luty, H. Murayama and R. Rattazzi, JHEP 9812, 027
 L. Randall and R. Sundrum, Nucl. Phys. B 557, 79 (1999).
 M. Dine and D. MacIntire, Phys. Rev. D 46, 2594 (1992) [hep-ph/9205227].
 H. Pagels and J. R. Primack, Phys. Rev. Lett. 48, 223 (1982); S. Weinberg,
Phys. Rev. Lett. 48, 1303 (1982); M. Y. .Khlopov and A. D. Linde, Phys. Lett.
B 138, 265 (1984).
 M. Kawasaki, K. Kohri and T. Moroi, Phys. Rev. D 71 (2005) 083502
[arXiv:astro-ph/0408426]; K. Jedamzik, Phys. Rev. D 74, 103509 (2006)
[arXiv:hep-ph/0604251]; M. Kawasaki, K. Kohri, T. Moroi and A. Yotsuyanagi,
Phys. Rev. D 78, 065011 (2008) [arXiv:0804.3745 [hep-ph]], and references
 M. Fukugita and T. Yanagida, Phys. Lett. B174 (1986) 45; For reviews,
W. Buchmuller, P. Di Bari and M. Plumacher, Annals Phys. 315, 305 (2005)
[hep-ph/0401240]; W. Buchmuller, R. D. Peccei and T. Yanagida, Ann. Rev.
Nucl. Part. Sci. 55, 311 (2005) [arXiv:hep-ph/0502169]; S. Davidson, E. Nardi
and Y. Nir, Phys. Rept. 466, 105 (2008) [arXiv:0802.2962 [hep-ph]].
 T. Gherghetta, G. F. Giudice and J. D. Wells, Nucl. Phys. B 559, 27 (1999)
 T. Moroi and L. Randall, Nucl. Phys. B 570, 455 (2000) [hep-ph/9906527].
 M. Ibe, R. Kitano, H. Murayama and T. Yanagida, Phys. Rev. D 70, 075012
(2004) [arXiv:hep-ph/0403198]; M. Ibe, R. Kitano and H. Murayama, Phys.
Rev. D 71, 075003 (2005) [arXiv:hep-ph/0412200].
 G. D. Coughlan, W. Fischler, E. W. Kolb, S. Raby and G. G. Ross, Phys. Lett.
B 131, 59 (1983).
 M. Ibe, Y. Shinbara and T. T. Yanagida, Phys. Lett. B 639, 534 (2006) [hep-
 K. Abe, T. Abe, H. Aihara, Y. Fukuda, Y. Hayato, K. Huang, A. K. Ichikawa
and M. Ikeda et al., arXiv:1109.3262 [hep-ex].
 ATLAS report, ATLAS-CONF-2011-163.
 CMS Collaboration, arXiv:1202.1487 [hep-ex].
 M. Ibe, T. Moroi and T. T. Yanagida, Phys. Lett. B 644, 355 (2007) [arXiv:hep-
 G. F. Giudice and A. Masiero, Phys. Lett. B 206, 480 (1988).
 N. Arkani-Hamed and S. Dimopoulos,JHEP 0506, 073 (2005) [hep-
 G. F. Giudice and A. Romanino, Nucl. Phys. B 699, 65 (2004) [Erratum-ibid.
B 706, 65 (2005)] [hep-ph/0406088].
 N. Arkani-Hamed, S. Dimopoulos, G. F. Giudice and A. Romanino, Nucl. Phys.
B 709, 3 (2005) [hep-ph/0409232].
 K. -I. Izawa, T. Kugo and T. T. Yanagida, Prog. Theor. Phys. 125, 261 (2011)
 J. D. Wells, Phys. Rev. D 71, 015013 (2005) [hep-ph/0411041].
 L. J. Hall and Y. Nomura, arXiv:1111.4519 [hep-ph].
 See e.g. Amar C. Vutha, Wesley C. Campbell, Yulia V. Gurevich, Nicholas R.
Hutzler, Maxwell Parsons, David Patterson, Elizabeth Petrik, Benjamin Spaun,
John M. Doyle, Gerald Gabrielse, David DeMille, arXiv:0908.2412[physics].
 A. Heister et al. [ALEPH Collaboration], Phys. Lett. B 533, 223 (2002) [hep-
 ATLAS reprot, ATLAS-CONF-2011-155
 Y. Okada, M. Yamaguchi and T. Yanagida, Phys. Lett. B 262, 54 (1991).
 N. Bernal, A. Djouadi and P. Slavich, JHEP 0707, 016 (2007) [arXiv:0705.1496
 G. F. Giudice and A. Strumia, Nucl. Phys. B 858, 63 (2012) [arXiv:1108.6077
 M. Lancaster [Tevatron Electroweak Working Group and for the CDF and D0
Collaborations], arXiv:1107.5255 [hep-ex].
 H. C. Cheng, B. A. Dobrescu and K. T. Matchev, Nucl. Phys. B 543, 47 (1999)
 J. Hisano, S. Matsumoto, M. Nagai, O. Saito and M. Senami, Phys. Lett. B
646, 34 (2007) [arXiv:hep-ph/0610249].
 T. Moroi and K. Nakayama, arXiv:1112.3123 [hep-ph].
 K. Jedamzik, Phys. Rev. D 70, 083510 (2004) [arXiv:astro-ph/0405583];
J. Hisano, M. Kawasaki, K. Kohri and K. Nakayama, Phys. Rev. D 79,
063514 (2009) [Erratum-ibid. D 80, 029907 (2009)] [arXiv:0810.1892 [hep-ph]];
J. Hisano, M. Kawasaki, K. Kohri, T. Moroi and K. Nakayama, Phys. Rev. D
79, 083522 (2009) [arXiv:0901.3582 [hep-ph]].
 B. Ezhuthachan, S. Mukhi and C. Papageorgakis,JHEP 0904, 101
(2009) [arXiv:0903.0003 [hep-th]]; T. R. Slatyer, N. Padmanabhan and
D. P. Finkbeiner, Phys. Rev. D 80, 043526 (2009) [arXiv:0906.1197 [astro-
ph.CO]]; T. Kanzaki, M. Kawasaki and K. Nakayama, Prog. Theor. Phys. 123,
853 (2010) [arXiv:0907.3985 [astro-ph.CO]]; J. Hisano, M. Kawasaki, K. Kohri,
T. Moroi, K. Nakayama and T. Sekiguchi, Phys. Rev. D 83, 123511 (2011)
[arXiv:1102.4658 [hep-ph]]; S. Galli, F. Iocco, G. Bertone and A. Melchiorri,
Phys. Rev. D 84, 027302 (2011) [arXiv:1106.1528 [astro-ph.CO]].
 J. Hisano, K. Ishiwata and N. Nagata, Phys. Lett. B 690, 311 (2010)
 J. Hisano, S. Matsumoto and M. M. Nojiri, Phys. Rev. Lett. 92, 031303 (2004)
[arXiv:hep-ph/0307216]; J. Hisano, S. Matsumoto, M. M. Nojiri and O. Saito,
Phys. Rev. D 71, 063528 (2005) [arXiv:hep-ph/0412403]; J. Hisano, S. Mat-
sumoto, O. Saito and M. Senami, Phys. Rev. D 73, 055004 (2006) [arXiv:hep-
 M. Ackermann et al. [Fermi-LAT collaboration], Phys. Rev. Lett. 107, 241302
(2011) [arXiv:1108.3546 [astro-ph.HE]].
 A. Hryczuk and R. Iengo, arXiv:1111.2916 [hep-ph].
 A. Charbonnier et al., Mon. Not. Roy. Astron. Soc. 418, 1526 (2011)
 O. Adriani et al. [PAMELA Collaboration], Phys. Rev. Lett. 105, 121101 (2010)
 C. Evoli, I. Cholis, D. Grasso, L. Maccione and P. Ullio, arXiv:1108.0664 [astro-
 O. Adriani et al. [PAMELA Collaboration],Nature 458, 607 (2009)
 P. Grajek, G. Kane, D. Phalen, A. Pierce and S. Watson, Phys. Rev. D 79,
043506 (2009) [arXiv:0812.4555 [hep-ph]]; G. Kane, R. Lu and S. Watson, Phys.
Lett. B 681, 151 (2009) [arXiv:0906.4765 [astro-ph.HE]].
 M. Toharia and J. D. Wells, JHEP 0602, 015 (2006) [arXiv:hep-ph/0503175];
P. Gambino, G. F. Giudice and P. Slavich, Nucl. Phys. B 726, 35 (2005)
 ATLAS Collaboration, ATLAS-CONF-2011-155.
 S. Asai, T. Moroi, K. Nishihara and T. T. Yanagida, Phys. Lett. B 653, 81
(2007) [arXiv:0705.3086 [hep-ph]].
 J. Alwall, K. Hiramatsu, M. M. Nojiri and Y. Shimizu, Phys. Rev. Lett. 103,
151802 (2009) [arXiv:0905.1201 [hep-ph]]; M. M. Nojiri and K. Sakurai, Phys.
Rev. D 82, 115026 (2010) [arXiv:1008.1813 [hep-ph]].
 A. Barr, C. Lester and P. Stephens, J. Phys. G 29, 2343 (2003) [arXiv:hep-
 S. Asai, T. Moroi and T. T. Yanagida, Phys. Lett. B 664, 185 (2008)
 M. Asano et al., Phys. Rev. D 84, 115003 (2011) [arXiv:1106.1932 [hep-ph]].