In this paper, we consider phenomenology of a model with an
gauge symmetry. Since the muon couples to the gauge boson
(called boson), its contribution to the muon anomalous magnetic moment
(muon g-2) can account...

Howard Baer, Mikael Berggren, Jenny List, Mihoko M. Nojiri, Maxim Perelstein, Aaron Pierce, Werner Porod, Tomohiko Tanabe

Jul 2013

The International Linear Collider (ILC) has recently proven its technical
maturity with the publication of a Technical Design Report, and there is a
strong interest in Japan to host such a machine. We summarize key aspects of
the Beyond the Standa...

Biplob Bhattacherjee, Shigeki Matsumoto, Satyanarayan Mukhopadhyay, Mihoko M. Nojiri

JHEP10(2013)032 Jun 2013 [Refereed]

Asymmetric dark matter (ADM) has been an attractive possibility attempting to
explain the observed ratio of baryon to dark matter abundance in the universe.
While a bosonic ADM is constrained by the limits from existence of old neutron
stars, a fe...

Present and future expected limits on interactions between dark matter and
various quarks are thoroughly investigated in a model-independent way. In
particular, the constraints on the interactions from the Large Hadron Collider
(LHC) experiment ar...

Biplob Bhattacherjee, Sourav K. Mandal, Mihoko Nojiri

JHEP 1303 (2013) 105 Nov 2012 [Refereed]

Top polarization is an important probe of new physics that couples to the top
sector, and which may be discovered at the 14 TeV LHC. Taking the example of
the MSSM, we argue that top polarization measurements can put a constraint on
the soft super...

Ben Gripaios, Keiko Nagao, Mihoko Nojiri, Kazuki Sakurai, Bryan Webber

JHEP 03(2013)106 Oct 2012 [Refereed]

We propose a method for reconstructing the mass of a particle, such as the
Higgs boson, decaying into a pair of tau leptons, of which one subsequently
undergoes a 3-prong decay. The kinematics is solved using information from the
visible decay pro...

In this paper we study the higgs-radion system of the Randall-Sundum model
where matter and gauge fields live in the bulk. We take into account the
Kalza-Klein(KK) loop correction for the higgs and the raidion coupling to the
gauge bosons. Inspire...

Keisuke Harigaya, Shigeki Matsumoto, Mihoko M. Nojiri, Kohsaku Tobioka

Apr 2012

Vector-like quarks are introduced in various new physics models beyond the
standard model (SM) at the TeV scale. We especially consider the case that the
quark is singlet (triplet) under the SU(2) (SU(3)) gauge group and
couples only to th...

Keisuke Harigaya, Shigeki Matsumoto, Mihoko M. Nojiri, Kohsaku Tobioka

JHEP 1201 (2012) 135 Sep 2011 [Refereed]

In the framework of the little higgs scenario, coupling constants of several
interactions are related to each other to guarantee the stability of the higgs
boson mass at one-loop level. This relation is called the little higgs
mechanism. We discus...

Hitoshi Murayama, Mihoko M. Nojiri, Kohsaku Tobioka

PhysRevD.84:094015,2011 Jul 2011 [Refereed]

We study the discovery potential of the Minimal Universal Extra Dimension
model (MUED) and improve it utilizing the multijet + lepton mode at the LHC.
Since the MUED has a nearly degenerate spectrum, most events only have soft
jets and small Emiss...

Subhaditya Bhattacharya, Sanjoy Biswas, Biswarup Mukhopadhyaya, Mihoko M. Nojiri

May 2011

We discuss large non-universality in the Higgs sector at high scale in
supersymmetric theories, in the context of the Large Hadron Collider (LHC). In
particular, we note that if is large and negative
($\simeq 10^6 {\rm ~G...

Daniele Alves, Nima Arkani-Hamed, Sanjay Arora, Yang Bai, Matthew Baumgart, Joshua Berger, Matthew Buckley, Bart Butler, Spencer Chang, Hsin-Chia Cheng, Clifford Cheung, R. Sekhar Chivukula, Won Sang Cho, Randy Cotta, Mariarosaria D'Alfonso, Sonia El Hedri, Rouven Essig, Jared A. Evans, Liam Fitzpatrick, Patrick Fox, Roberto Franceschini, Ayres Freitas, James S. Gainer, Yuri Gershtein, Richard Gray, Thomas Gregoire, Ben Gripaios, Jack Gunion, Tao Han, Andy Haas, Per Hansson, JoAnne Hewett, Dmitry Hits, Jay Hubisz, Eder Izaguirre, Jared Kaplan, Emanuel Katz, Can Kilic, Hyung-Do Kim, Ryuichiro Kitano, Sue Ann Koay, Pyungwon Ko, David Krohn, Eric Kuflik, Ian Lewis, Mariangela Lisanti, Tao Liu, Zhen Liu, Ran Lu, Markus Luty, Patrick Meade, David Morrissey, Stephen Mrenna, Mihoko Nojiri, Takemichi Okui, Sanjay Padhi, Michele Papucci, Michael Park, Myeonghun Park, Maxim Perelstein, Michael Peskin, Daniel Phalen, Keith Rehermann, Vikram Rentala, Tuhin Roy, Joshua T. Ruderman, Veronica Sanz, Martin Schmaltz, Stephen Schnetzer, Philip Schuster, Pedro Schwaller, Matthew D. Schwartz, Ariel Schwartzman, Jing Shao, Jessie Shelton, David Shih, Jing Shu, Daniel Silverstein, Elizabeth Simmons, Sunil Somalwar, Michael Spannowsky, Christian Spethmann, Matthew Strassler, Shufang Su, Tim Tait, Brooks Thomas, Scott Thomas, Natalia Toro, Tomer Volansky, Jay Wacker, Wolfgang Waltenberger, Itay Yavin, Felix Yu, Yue Zhao, Kathryn Zurek

2012 J. Phys. G: Nucl. Part. Phys. 39 105005 May 2011

This document proposes a collection of simplified models relevant to the
design of new-physics searches at the LHC and the characterization of their
results. Both ATLAS and CMS have already presented some results in terms of
simplified models, and...

We consider the spin determination of new colored particles in the missing
energy plus jets channel at the early stage of LHC. We use a three site moose
model to describe the low energy Lagrangian of all same spin partner (LHT or
UED like) models ...

We report a new possibility of using the (Constransverse mass)
variable for mass measurement in single step decay chains involving missing
particles with moderate transverse momentum. We show that its experimental
feasibility is enhanced c...

A method is proposed for determining the masses of the new particles N,X,Y,Z
in collider events containing a pair of effectively identical decay chains Z to
Y+jet, Y to X+l_1, X to N+l_2, where l_1, l_2 are opposite-sign same-flavour
charged lepto...

Chuan-Ren Chen, Mihoko M. Nojiri, Seong Chan Park, Jing Shu

Aug 2009

Kaluza-Klein photon in universal extra dimension models is one of the most
attractive dark matter candidates as a weakly interacting massive particle.
Having a characteristic split spectrum in split universal extra dimension the
relic density of K...

Sung-Gi Kim, Nobuhiro Maekawa, Keiko I. Nagao, Mihoko M. Nojiri, Kazuki Sakurai

JHEP 0910:005,2009 Jul 2009

We study the LHC signature of the minimal supersymmetric standard model with
non-universal sfermion masses. In the model, soft masses of gauginos and the
3rd generation of 10 of SU(5) are around the weak scale, while other sfermion
soft mass is un...

Johan Alwall, Kenji Hiramatsu, Mihoko M. Nojiri, Yasuhiro Shimizu

Phys.Rev.Lett.103:151802,2009 May 2009

At hadron colliders, the production of heavy new particles is associated with
additional quarks and gluons with significant transeverse momentum. The
additional jets complicates the reconstruction of new particle masses. Taking
gluino pair product...

We investigate the observed spectrum of cosmic-ray electrons and positrons
from astrophysical sources, especially pulsars, and the physical processes for
making the spectrum spiky or smooth via continuous and multiple
electron/positron injections....

Chuan-Ren Chen, Mihoko M. Nojiri, Seong Chan Park, Jing Shu, Michihisa Takeuchi

Mar 2009

We explicitly show that split-universal extra dimension (split-UED), a
recently suggested extension of universal extra dimension (UED) model, can
nicely explain recent anomalies in cosmic-ray positrons and electrons observed
by PAMELA and ATIC/PPB...

Junji Hisano, Mihoko M. Nojiri, Warintorn Sreethawong

JHEP 0906:044,2009 Dec 2008

Current limit on the dark matter relic abundance may suggest that
should be smaller than prediction in the minimal supergravity scenario (mSUGRA)
for moderate and . The electroweak-ino parameter and
are th...

Chuan-Ren Chen, Mihoko M. Nojiri, Fuminobu Takahashi, T. T. Yanagida

Prog.Theor.Phys.122:553-559,2009 Nov 2008

We show that the PAMELA anomaly in the positron fraction as well as the
ATIC/PPB-BETS excesses in the e^- + e^+ flux are simultaneously explained in
our scenario that a hidden U(1)H gauge boson constitutes dark matter of the
Universe and decays in...

I review recent developments on the use of mT2 variables for SUSY parameter
study, which might be useful for the data analysis in the early stage of the
LHC experiments. I also review some of recent interesting studies. Talk in
SUSY08.

Mihoko M. Nojiri, Kazuki Sakurai, Yasuhiro Shimizu, Michihisa Takeuchi

JHEP0810:100,2008 Aug 2008

The ATLAS and CMS experiments at the Large Hadron Collider (LHC) may discover
the squarks (\tilde{q}) and gluino (\tilde{g}) of the minimal supersymmetric
standard model (MSSM) in the early stage of the experiments if their masses are
lighter than...

In the Littlest Higgs model with T-parity (LHT), top-partners (T_-) are
produced in pairs at the Large Hadron Collider (LHC). Each top-partner decays
into a top quark (t) and the lightest T-odd gauge partner A_H. We demonstrate
reconstruction of t...

Mihoko M. Nojiri, Yasuhiro Shimizu, Shogo Okada, Kiyotomo Kawagoe

JHEP0806:035,2008 Feb 2008

We propose an inclusive analysis of a stransverse mass (m_{T2}) using a
hemisphere method for supersymmetry studies at the LHC . The hemisphere method
is an algorithm to group collinear and high p_T particles and jets, assuming
that there are two ...

We now believe that the dark matter in our Universe must be an unknown elementray particle, which is charge neutral and weakly interacting. The standard model must be extended to include it. The dark matter was likely produced in the early univers...

production is one of the main SUSY production
processes in the MSSM, which occurs due to the chirality flip caused by the
Majorana gluino mass. This process is one of the sources of same sign two
lepton (SS2) events, h...

Shigeki Matsumoto, Mihoko M. Nojiri, Daisuke Nomura

Phys.Rev.D75:055006,2007 Dec 2006

We study the Littlest Higgs model with T-parity at the LHC through pair
productions of the T-odd top quark partner (T_-) which decays into the top
quark and the lightest T-odd particle. We identify the region of parameters
favored by the electrowe...

Koichi Hamaguchi, Mihoko M. Nojiri, Albert de Roeck

JHEP 0703:046,2007 Dec 2006

If the scalar tau is the next lightest supersymmetric particle and
decays into a gravitino () being the lightest supersymmetric
particle, it will have generally a very long lifetime. In this paper, we
investigate the possibilit...

Discovery of supersymmetric (SUSY) particles at the Large Hadron
Collider(LHC) has been studied for the models where squarks and gluino are much
heavier than the lightest supersymetric particle (LSP). In this paper, we
investigate the SUSY discove...

Junji Hisano, Minoru Nagai, Mihoko M. Nojiri, Masato Senami

Phys.Rev. D73 (2006) 031701 Apr 2005

We investigate a possibility of neutralino dark matter (DM) direct detection
in the future electron accelerators. That is counting of high p_T electron
recoil events by neutralinos in halo. If selectron and neutralino masses would
be precisely mea...

Junji Hisano, Shigeki. Matsumoto, Mihoko M. Nojiri, Osamu Saito

Phys.Rev. D71 (2005) 063528 Dec 2004

Detection of gamma rays from dark matter annihilation in the galactic center
is one of the feasible techniques to search for dark matter. We evaluate the
gamma ray flux in the case that the dark matter has an electroweak SU(2)_L
charge. Such dark ...

The lighter chargino pair production () is one of key processes for determination of
supersymmetric parameters at a linear collider. If is a large
value, the lighter stau ($\tilde{\...

At the LHC, superpartners with the masses lighter than a few TeV may be
found, and the masses of the supersymmetric (SUSY) particles and their
interactions will be studied. The information would be the base to consider the
SUSY breaking mechanism ...

Koichi Hamaguchi, Yoshitaka Kuno, Tsuyoshi Nakaya, Mihoko M. Nojiri

Phys.Rev.D70:115007,2004 Sep 2004

In models where the gravitino is the lightest supersymmetric particle (LSP),
the next-to-lightest supersymmetric particle (NLSP) is long-lived. We consider
an important charged NLSP candidate, the scalar tau . Slow
charged NLSPs may ...

Junji Hisano, Shigeki Matsumoto, Mihoko M. Nojiri, Osamu Saito

Phys.Rev. D71 (2005) 015007 Jul 2004

The neutralino-nucleon (\tilde{\chi}^0-N) scattering is an important process
for direct dark matter searches. In this paper we discuss one-loop
contributions to the cross section in the wino-like and Higgsino-like LSP
cases. The neutralino-nucleon...

SUSY DARK MATTER: A COLLIDER PHYSICIST'S PERSPECTIVE.

Pramana 62:335-346 2004

STUDY OF STOP AND SBOTTOM AT LHC.

Pramana--jounal of physics (Indian Academy of Sciences) 62:659-662 2004

Kiyotomo Kawagoe, Tomio Kobayashi, Mihoko M. Nojiri, Atsuhiko Ochi

Phys.Rev. D69 (2004) 035003 Sep 2003

In this paper we study the gauge mediation signal with the ATLAS detector at
the CERN LHC. We focus on the case where the NLSP is the long-lived lightest
neutralino () which decays dominantly into a photon
() and a gravit...

If the Dark Matter (DM) in the Universe has interactions with the
standard-model particle, the pair annihilation may give the imprints in the
cosmic ray. In this paper we study the pair annihilation processes of the DM,
which is neutral, however h...

In supersymmetric models a gluino can decay into
through a stop or a sbottom. The decay chain produces an edge structure in the
distribution. Monte Carlo simulation studies show that the end point
and the edge hei...

In supersymmetric models a gluino can decay into tb\tilde{\chi}^{\pm}_1
through a stop or a sbottom. The decay chain produces an edge structure in the
m_{tb} distribution. Monte Carlo simulation studies show that the end point and
the edge height ...

The neutralino pair annihilation into two photons in our galactic halo gives
a robust dark matter signal, since it would give a quasi-monotonic gamma ray.
This process is radiatively-induced, and the full-one loop calculation was done
previously. ...

We present a pedagogical introduction to supersymmetry and supersymmetric
models and give an overview of the potential of the linear collider for
studying them. If supersymmetry is found, its discovery will bring with it many
more questions than a...

Junji Hisano, Kiyotomo Kawagoe, Ryuichiro Kitano, Mihoko M. Nojiri

Phys.Rev. D66 (2002) 115004 Apr 2002

In the minimal supersymmetric standard model (MSSM) properties of the third
generation sfermions are important from the viewpoint of discriminating the
SUSY breaking models and in the determination of the Higgs boson mass. If
gluinos are copiously...

Measurement of Lepton-Flavor Violation (LFV) in the minimal SUSY Standard
Model (MSSM) at Large Hadron Collider (LHC) is studied based on a realistic
simulation. We consider the LFV decay of the second-lightest neutralino,
$\tilde{\chi}^0_2 \to \t...

We investigate the implications of the recent measurement of muon anomalous
magnetic moment for the direct detection of neutralino dark matter in the three
different SUSY models: mSUGRA, a model with non-universal Higgs mass, and an
SO(10) GUT mod...

The gauge-mediated SUSY-breaking (GMSB) model needs entropy production at a
relatively low temperature in the thermal history of the Universe for the
unwanted relics to be diluted. This requires a mechanism for the baryogenesis
after the entropy p...

We show that LHC experiments might well be able to determine all the parameters required for a prediction of the present density of thermal LSP relics from the Big Bang era. If the LSP is an almost pure bino we usually only need to determine its m...

Manuel Drees, Yeong Gyun Kim, Tatsuo Kobayashi, Mihoko M. Nojiri

Phys.Rev.D63:115009,2001 Nov 2000

We compare predictions for the spin-independent contribution to the
neutralino-proton scattering cross section and for the anomalous
magnetic dipole moment of the muon, , in models with
gravity-mediated supersymmetry br...

Manuel Drees, Yeong Gyun Kim, Mihoko M. Nojiri, Daisuke Toya, Kazumi Hasuko, Tomio Kobayashi

Phys.Rev.D63:035008,2001 Jul 2000

We show that LHC experiments might well be able to determine all the
parameters required for a prediction of the present density of thermal LSP
relics from the Big Bang era. If the LSP is an almost pure bino we usually only
need to determine its m...

We study the distribution of lepton pairs from the second lightest neutralino
decay \tilde{\chi}^0_2-->\tilde{l}l followed by \tilde{l}\to \tilde{\chi}^0_1
l. The distribution of the ratio of lepton transverse momenta A_T shows peak
structure if m...

Lepton energy asymmetry and precision SUSY study at hadron Collider

We study the distribution of lepton pairs from the second lightest neutralino
decay \tchi^0_2\to\tchi^0_1 l^+l^-. This decay mode is important to measure the
mass difference between \tchi^0_2 and the lightest neutralino \tchi^0_1, which
helps to d...

Lepton flavor violation in the left-handed slepton production at future lepton colliders

Physical Review D 60 1999

Neutralino Decays at the LHC

Phys. Rev D60 : 015006 60 1999

Supersymmetry and Future Collider

Proceeding of KIAS-CTP International Symposium on Supersymmetry, Supergravity and Superstring 204 1999

Junji Hisano, Mihoko M. Nojiri, Yasuhiro Shimizu, Minoru Tanaka

Phys.Rev. D60 (1999) 055008 Aug 1998

The Super-Kamiokande atmospheric neutrino data suggest existence of the large
lepton-flavor violating (LFV) interaction in the higher energy scale. If the
minimal supersymmetric standard model is extended to have right-handed
neutrinos, the left-h...

Shingo Kiyoura, Mihoko M. Nojiri, Damien M. Pierce, Youichi Yamada

Phys.Rev. D58 (1998) 075002 Mar 1998

Recently it has been realized that the production and decay processes of
charginos, neutralinos, and sleptons receive corrections which grow like log
m_squark for large m_squark. In this paper we calculate the chargino pair
production cross sectio...

Radiative Corrections to A Supersymmetric Relation : A NEW APPROACH

In the case with a large splitting between the squark and slepton masses, the
supersymmetric identities which enforce the equality of the gauge and gaugino
couplings are violated in the effective theory below the squark mass threshold.
We compute ...

Mihoko M. Nojiri, Damien M. Pierce, Youichi Yamada

Phys.Rev. D57 (1998) 1539-1552 Jul 1997

We investigate an important radiative correction to the slepton and chargino
production processes. We consider a supersymmetric spectrum with a large
splitting between the squark and slepton masses. In this case, in the effective
theory below the ...

Mihoko M. Nojiri, Keisuke Fujii, Toshifumi Tsukamoto

Phys.Rev. D54 (1996) 6756-6776 Jun 1996

Sleptons can easily be found at future linear e+e- colliders if kinematically
accessible. Measurements of their masses and decay distributions would then
determine MSSM parameters. This paper presents a detailed MC study of the
production and deca...

Keisuke Fujii, Mihoko M. Nojiri, Toshifumi Tsukamoto

Prog.Theor.Phys.Suppl. 123 (1996) 203-212 Nov 1995

The lighter scalar tau lepton may be the lightest scalar lepton and
therefore would be found earlier in future collider experiments. We point out
the impact of the measurement of the mass and the mixing angle of to
discriminate the mo...

Study of the production and decay of scalar tau lepton () at future
colliders helps to determine the value of through the
measurement of the polarization of lepton that arises from decay.
Key maps of the param...

The lepton arising from the scalar tau () decay is naturally
polarized. depends on the left--right mixing of the and the
gaugino--higgsino mixing of the neutralino. The polarization could be
measured from the ener...

Francesca M. Borzumati, Manuel Drees, Mihoko M. Nojiri

Phys.Rev. D51 (1995) 341-347 Jun 1994

We point out that combinations of parameters that predict large counting
rates in experiments searching for supersymmetric dark matter often tend to
predict a very large branching ratio for the inclusive decay \bsg. The recent
measurement of this...