Da-Shin Lee, National Dong-Hwa University
Analog Model of Quantum Phenomena in Curved Spacetime Using Cold Atomic Condensates
Meeting room 3, Kenkyu honkan 1F We explore possible analogies between quantum phenomena in curved spacetime and cold laboratory condensates whose speed of sound can be tuned by means of an external field. In the first instance, the creation of causal horizons when a system undergoes rapid changes can lead to the creation of defects e.g. cosmic strings and monopoles. We see to what extent this can be mimicked in condensates by the spontaneous creation of vortices in a field ramp. Secondly, by examining the phonon geodesics in the acoustic metric we can look for spontaneous phonon creation that mimics spontaneous particle creation in curved space-time. Also, the fluctuating nature of the phonon background suggests analogies with quantum gravity.
We explore possible analogies between quantum phenomena in curved spacetime and cold laboratory condensates whose speed of sound can be tuned by means of an external field. In the first instance, the creation of causal horizons when a system undergoes rapid changes can lead to the creation of defects e.g. cosmic strings and monopoles. We see to what extent this can be mimicked in condensates by the spontaneous creation of vortices in a field ramp. Secondly, by examining the phonon geodesics in the acoustic metric we can look for spontaneous phonon creation that mimics spontaneous particle creation in curved space-time. Also, the fluctuating nature of the phonon background suggests analogies with quantum gravity.
References:
[1] D.-S. Lee, C. Y. Lin, and R. J. Rivers: “Derivation of Hydrodynamics for the Gapless Mode in the BEC-BCS Crossover from the Exact One-Loop Effective Action,” Phys. Rev. Lett. 98, 020603 (2007).
[2] C.-Y. Lin, D.-S. Lee, and R. J. Rivers, “The role of Causality in Tunable Fermi Gas Condensates,” J. Phys. Cond. Matter 25, 04211 (2013).
[3] J.-T. Hsiang, C.-Y. Lin, D.-S. Lee, and R. J. Rivers, “Quantum Stochastic Behavior in Cold Fermi Gases: Phonon Propagation,” Phys. Rev. A 91, 051603(R) (2015).
Naoki Yoshida, Tokyo Univ.
Cosmological constraints on dark matter annihilation and decay
Meeting room 3, Kenkyu honkan 1F
We present the results from cross-correlation analysis of weak gravitational lensing and the extra-galactic gamma-ray radiation. The former provides the large scale distribution of dark matter, and the latter possibly includes high energy photons produced by dark matter self-annihilation or decay. We use data from CFHT, SDSS, RCSLens galaxy surveys and the Fermi all-sky survey. We generate a large set of full-sky mock catalogs from cosmological N-body simulations and use them to estimate statistical errors accurately. The measured cross-correlation is consistent with null detection, which is then used to place strong cosmological constraints on annihilating and decaying DM. For leptophilic DM, the constraints are improved by a factor of 100 in the mass range of ~TeV when including contributions from secondary gamma-rays due to the inverse -Compton upscattering of background photons. Annihilation cross sections of 10^{-23} cm3/s are excluded for TeV-scale DM. Lifetimes of 10^25 sec are also excluded for the decaying TeV-scale DM. These are real cosmological constraints, rather than being obtained from local structures.
Eigo Shintani, RIKEN-AICS
Lattice computation of nucleon matrix element related to BSM physics
Meeting room 1, Kenkyu honkan 1F
I will review the recent nucleon matrix element computation related to BSM physics, e.g. EDM, proton decay, etc, in lattice QCD.
Hiroaki Sugiyama, Toyama Univ.
Exploring neutrino mass generation mechanisms via the lepton flavor violating decay of the Higgs boson
Meeting room 1, Kenkyu honkan 1F There are many new physics models for generating neutrino masses, and it is important to consider how these models can be experimentally discriminated. Classification of models is useful for the efficient discrimination. In this talk, we classify simple models for each of Majorana and Dirac neutrino masses by concentrating on Yukawa interactions with leptons. We see that, if a lepton flavor violating decay of the Higgs boson is discovered, simple models for Majorana neutrino masses are excluded while some models for Dirac neutrino masses can survive.
There are many new physics models for generating neutrino masses, and it is important to consider how these models can be experimentally discriminated. Classification of models is useful for the efficient discrimination. In this talk, we classify simple models for each of Majorana and Dirac neutrino masses by concentrating on Yukawa interactions with leptons. We see that, if a lepton flavor violating decay of the Higgs boson is discovered, simple models for Majorana neutrino masses are excluded while some models for Dirac neutrino masses can survive.
[1] S. Kanemura and H. Sugiyama, Phys. Lett. B753, 161 (2016). [2] S. Kanemura, K. Sakurai and H. Sugiyama, Phys. Lett. B758, 465 (2016). [3] M. Aoki, S. Kanemura, K. Sakurai and H. Sugiyama, Phys. Lett. B763, 352 (2016).
Ignatios Antoniadis, University of Bern
Aspects of string phenomenology and scale hierarchies
Meeting room 3, Kenkyu honkan 1F
I will discuss the problem of scale hierarchies in string phenomenology of particle physics and cosmology and propose ways to address it. In particular I will present a mechanism for supersymmetry breaking in the presence of a tiny (tunable) positive cosmological constant and describe its phenomenological consequences
Ryosuke Sato, Weizmann Inst.
Spherical symmetry of the bounce solution
Meeting room 3, Kenkyu honkan 1F
In his 1977 paper on vacuum decay in field theory: The Fate of the False Vacuum, Coleman considered the problem of a single scalar field and assumed that the minimum action tunnelling field configuration, the bounce, is invariant under O(4) rotations in Euclidean space. A proof of the O(4) invariance of the bounce was provided later by Coleman, Glaser, and Martin (CGM), who extended the proof to N > 2 Euclidean dimensions but, again, restricted non-trivially to a single scalar field. As far as we know a proof of O(N) invariance of the bounce for the tunnelling problem with multiple scalar fields has not been reported, even though it was assumed in many works since, being of phenomenological interest. We make progress towards closing this gap. Following CGM we define the reduced problem of finding a field configuration minimizing the kinetic energy at fixed potential energy. Given a solution of the reduced problem, the minimum action bounce can always be obtained from it by means of a scale transformation. We show that if a solution of the reduced problem exists, then it and the minimum action bounce derived from it are indeed O(N) symmetric.
Takahiro Terada, KIAS
Non-thermal Gravitino Production after Large-Field Inflation
Meeting room 1, Kenkyu honkan 1F
Gravitino abundance is a crucially important quantity in cosmology with supersymmetry. We revisit non-thermal gravitino production after inflation in supergravity paying particular attention to inflation models with a stabilizer field, in which gravitino production by preheating has not been studied. This analysis is particularly important for Z_2 symmetric large-field models, to which perturbative analyses in the literature are not applicable. We find that the transverse gravitino abundance, which is the dominant component in the case without a stabilizer field, is much suppressed in the case with a stabilizer field. The case of the inflaton potential quartic around the minimum without the stabilizer field predicts too many gravitinos, while the cases of the quadratic potential or with a stabilizer field predicts non-thermal gravitino abundance less than the thermal contribution.
Satoshi Shirai, Kavli IPMU
Search for wino dark matter
Meeting room 3, Kenkyu honkan 1F
Wino is one of the most attractive candidates for the dark matter. I will talk about characteristic signatures of the wino at the colliders and in the sky, and discuss the possibility of further improvement of the wino search.
Shigehiro Yasui, Tokyo Institute of Technology
Kondo effects in nuclear and quark matter
Meeting room 1, Kenkyu honkan 1F
The Kondo effect is a well-known phenomena that there is an enhancement of the electric resistance of electrons in metal containing impurity atoms with finite spin at low temperature. The conditions of the emergence of the Kondo effect are summarized as (i) Fermi surface (degenerate state) (ii) loop effect (particle-hole creation) and (iii) non-Abelian interaction. Those conditions can be satisfied for nuclear matter and quark matter where heavy hadrons and quarks are contained as immunity particles in the medium. In this presentation, I will introduce the recent studies of the Kondo effects in nuclear matter and quark matter, whose results may be studied in experiments in J-PARC, GSI-FAIR, NICA as well as in RHIC and LHC.
Gokce Basar, University of Maryland
Resurgence theory and quantum geometry
Meeting room 3, Kenkyu honkan 1F
