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J. Hisano

Publications and source records attributed to J. Hisano.

At least 19 recordsLinked to original sources
arXiv2019

The Belle II Physics Book

We present the physics program of the Belle II experiment, located on the intensity frontier SuperKEKB $e^+e^-$ collider. Belle II collected its first collisions in 2018, and is expected to operate for the next decade. It is anticipated to collect 50/ab of collision data over its lifetime. This book is the outcome of a joint effort of Belle II collaborators and theorists through the Belle II theory interface platform (B2TiP), an effort that commenced in 2014. The aim of B2TiP was to elucidate the potential impacts of the Belle II program, which includes a wide scope of physics topics: B physics, charm, tau, quarkonium, electroweak precision measurements and dark sector searches. It is composed of nine working groups (WGs), which are coordinated by teams of theorist and experimentalists conveners: Semileptonic and leptonic B decays, Radiative and Electroweak penguins, phi_1 and phi_2 (time-dependent CP violation) measurements, phi_3 measurements, Charmless hadronic B decay, Charm, Quarkonium(like), tau and low-multiplicity processes, new physics and global fit analyses. This book highlights "golden- and silver-channels", i.e. those that would have the highest potential impact in the field. Theorists scrutinised the role of those measurements and estimated the respective theoretical uncertainties, achievable now as well as prospects for the future. Experimentalists investigated the expected improvements with the large dataset expected from Belle II, taking into account improved performance from the upgraded detector.

hep-ex↗
arXiv2010

Physics at Super B Factory

This report presents the results of studies that investigate the physics reach at a Super $B$ factory, an asymmetric-energy $e^+e^-$ collider with a design luminosity of $8 \times 10^{35}$ cm$^{-2}$s$^{-1}$, which is around 50 times as large as the peak luminosity achieved by the KEKB collider. The studies focus on flavor physics and CP violation measurements that could be carried out in the LHC era. The physics motivation, key observables, measurement methods and expected precisions are presented.

hep-ex↗
arXiv2009

Waiting for mu->eg from the MEG experiment

The Standard Model (SM) predictions for the lepton flavor-violating (LFV) processes like mu->eg are well far from any realistic experimental resolution, thus, the appearance of m->eg at the running MEG experiment would unambiguously point towards a New Physics (NP) signal. In this article, we discuss the phenomenological implications in case of observation/improved upper bound on m->eg at the running MEG experiment for supersymmetric (SUSY) scenarios with a see-saw mechanism accounting for the neutrino masses. We outline the role of related observables to m->eg in shedding light on the nature of the SUSY LFV sources providing useful tools i) to reconstruct some fundamental parameters of the neutrino physics and ii) to test whether an underlying SUSY Grand Unified Theory (GUT) is at work. The perspectives for the detection of LFV signals in tau decays are also discussed.

hep-ph↗
arXiv2008

"Flavored" Electric Dipole Moments in Supersymmetric Theories

The Standard Model (SM) predictions for the hadronic electric dipole moments (EDMs) are well far from the present experimental resolutions, thus, the EDMs represent very clean probes of New Physics (NP) effects. Especially, within an MSSM framework with flavor-changing (but not necessarily CP violating) soft terms, large and potentially visible effects to the EDMs are typically expected. In this Letter we point out that, beyond-leading-order (BLO) effects, so far neglected in the literature, dominate over the leading-order (LO) effects in large regions of the parameter space, hence, their inclusion in the evaluation of the hadronic EDMs is unavoidable.

hep-ph↗
arXiv2008

Flavour physics of leptons and dipole moments

This chapter of the report of the ``Flavour in the era of the LHC'' Workshop discusses the theoretical, phenomenological and experimental issues related to flavour phenomena in the charged lepton sector and in flavour-conserving CP-violating processes. We review the current experimental limits and the main theoretical models for the flavour structure of fundamental particles. We analyze the phenomenological consequences of the available data, setting constraints on explicit models beyond the Standard Model, presenting benchmarks for the discovery potential of forthcoming measurements both at the LHC and at low energy, and exploring options for possible future experiments.

hep-ph↗
arXiv2005

The Discovery Potential of a Super B Factory

The Proceedings of the 2003 SLAC Workshops on flavor physics with a high luminosity asymmetric e+e- collider. The sensitivity of flavor physics to physics beyond the Standard Model is addressed in detail, in the context of the improvement of experimental measurements and theoretical calculations.

hep-ph↗
arXiv2004

Physics Interplay of the LHC and the ILC

Physics at the Large Hadron Collider (LHC) and the International e+e- Linear Collider (ILC) will be complementary in many respects, as has been demonstrated at previous generations of hadron and lepton colliders. This report addresses the possible interplay between the LHC and ILC in testing the Standard Model and in discovering and determining the origin of new physics. Mutual benefits for the physics programme at both machines can occur both at the level of a combined interpretation of Hadron Collider and Linear Collider data and at the level of combined analyses of the data, where results obtained at one machine can directly influence the way analyses are carried out at the other machine. Topics under study comprise the physics of weak and strong electroweak symmetry breaking, supersymmetric models, new gauge theories, models with extra dimensions, and electroweak and QCD precision physics. The status of the work that has been carried out within the LHC / LC Study Group so far is summarised in this report. Possible topics for future studies are outlined.

hep-ph↗
arXiv2004

Physics at Super B Factory

This report presents the results of studies that investigate the physics reach at a Super B factory, an asymmetric-energy e^+e^- collider with a design luminosity of 5 x 10^35 cm^-2s^-1, which is around 40 times as large as the peak luminosity achieved by the KEKB collider. The studies focus on flavor physics and CP violation measurements that could be carried out in the LHC era. The physics motivation, key observables, measurement methods and expected precisions are presented. The sensitivity studies are a part of the activities associated with the preparation of a Letter of Intent for SuperKEKB, which has been submitted recently.

hep-ex↗
arXiv2002

Probing physics beyond the standard model from lepton sector

In this review we discuss physics of the lepton sector, the anomalous dipole moment of muon, the charged lepton-flavor violation, and the electric dipole moments of charged leptons, from viewpoints of the minimal supersymmetric standard model and the extensions.

hep-ph↗
arXiv2000

Neutralino Warm Dark Matter

In the supersymmetric (SUSY) standard model, the lightest neutralino may be the lightest SUSY particle (LSP), and it is is a candidate of the dark matter in the universe. The LSP dark matter might be produced by the non-thermal process such as heavy particle decay after decoupling of the thermal relic LSP. If the produced LSP is relativistic, and does not scatter enough in the thermal bath, the neutralino LSP may contribute as the warm dark matter (WDM) to wash out the small scale structure of O(0.1) Mpc. In this letter we calculate the energy reduction of the neutralino LSP in the thermal bath and study whether the LSP can be the WDM. If temperature of the production time T_I is smaller than 5MeV, the bino-like LSP can be the WDM and may contribute to the small-scale structure of O(0.1) Mpc. The Higgsino-like LSP might also work as the WDM if T_I< 2MeV. The wino-like LSP cannot be the WDM in the favoured parameter region.

hep-ph↗
arXiv2000

Neutrino Oscillation and Charged Lepton-Flavor Violation in the Supersymmetric Standard Models

The neutrino experiment results suggest that the neutrinos have finite masses and the lepton-flavor symmetries are violating in nature. In the supersymmetric models, the charged lepton-flavor violating processes, such as mu -> e gamma and tau -> mu gamma, may have the branching ratios accessible to the future experiments, depending on origins of the neutrino masses and the SUSY breaking. In this paper we discuss the branching ratios in the supergravity scenario using the current solar and atmospheric neutrino experimental data.

hep-ph↗
arXiv1999

Lepton-Flavor Violation at Future Lepton Colliders and the Atmospheric Neutrino Oscillation

It can be expected from the result for the atmospheric neutrino by the SUPERKAMIOKANDE and the CHOOZ result that the the lepton-flavor violating (LFV) interaction between the second and third generations exits at the high energy scale. This leads to a non-vanishing LFV left-handed slepton mass between the second and third generations, induced by the radiative correction, in the minimal supergravity scenario. In this article, assuming that the supersymmetric standard model with the right-handed neutrinos explains the atmospheric neutrino result, we show that the reach of the LFV slepton production in the future lepton colliders can be more significant than that of tau -> mu gamma.

hep-ph↗
arXiv1999

Solar and Atmospheric Neutrino Oscillations and Lepton Flavor Violation in Supersymmetric Models with Right-handed Neutrinos

Taking the solar and the atmospheric neutrino experiments into account we discuss the lepton flavor violating processes, such as $τ\toμγ$ or $μ\to eγ$, in the minimal supersymmetric standard model with right-handed neutrinos (MSSMRN) and the supersymmetric SU(5) GUT with right-handed neutrinos (SU(5)RN). The predicted branching ratio of $μ\to eγ$ in the MSSMRN with the MSW large angle solution is so large that it goes beyond the current experimental bound if the second-generation right-handed Majorana mass $M_{ν_2}$ is greater than $\sim 10^{13}(\sim 10^{14})$GeV for $\tanβ=30(3)$. When we take the MSW small angle solution, the $μ\to eγ$ rate is at most about 1/100 of that of the MSW large angle solution. The 'just so' solution implies $10^{-5}$ of that of the MSW large angle solution. Also, in the SU(5)RN the large $μ\to eγ$ rate naturally follows from the MSW large angle solution, and the predicted rate is beyond the current experimental bound if the typical right-handed Majorana mass $M_N$ is larger than $\sim 10^{13}(\sim 10^{14})$GeV for $\tanβ=30(3)$, similarly to the MSSMRN. We show the multimass insertion formulas and their applications to $τ\toμγ$ and $μ\to eγ$.

hep-ph↗
arXiv1998

Large Squark and Slepton Masses for the First-Two Generations in the Anomalous U(1) SUSY Breaking Models

Considering that the soft SUSY breaking scalar masses come from a vacuum expectation value of the D-term for an external gauge multiplet, the renormalization of the scalar masses is related to the gauge anomaly. Then, if the external gauge symmetry is anomaly-free and has no kinetic mixing with the other U(1) gauge symmetries, the scalar masses are non-renormalized at all orders assuming that the gaugino masses are negligibly small compared with the scalar masses. Motivated by this, we construct models where the sfermion masses for the first-two generations are much heavier than the other superparticles in the minimal SUSY standard model in a framework of the anomalous U(1) mediated SUSY breaking. In these models we have to introduce extra chiral multiplets with the masses as large as those for the first-two generation sfermions. We find that phenomenologically desirable patterns for the soft SUSY breaking terms can be obtained in the models.

hep-ph↗
arXiv1998

Lepton-Flavor Violation in Supersymmetric Models

Theoretical aspects of lepton-flavor violating (LFV) processes on the supersymmetric models are reviewed. In particular, we show that, assuming the minimal supergravity scenario, the LFV interaction at the higher energy scale leads to the the LFV processes, which may be accessible in near future experiments.

hep-ph↗
arXiv1998

Enhancement of μ\to e γin the supersymmetric SU(5) GUT at large \tanβ

Branching ratio of $μ\to \e γ$ is evaluated in the supersymmetric SU(5) grand unified theory taking account of higher dimensional operators, which reproduce the realistic quark and lepton masses and the mixing parameters. It is shown by numerical calculation that at large $\tanβ$ the branching ratio is enhanced by a few orders of magnitude since the flavor mixings for both the left- and the right-handed sleptons are induced by the effect of the higher dimensional operators.

hep-ph↗