Hidehiko Shimada, Okayama Institute for Quantum Physics
Membrane interaction and a three-dimensional analog of Riemann surfaces
Seminar room, Kenkyu honkan 3F
It is an important problem to understand whether the matrix model of M-theory contains the splitting(-joining) interactions of membranes. In the talk, I will discuss the splitting processes in the pp-wave matrix model, which are certain tunnelling processes. After a brief discussion of the relation to the ABJM theory via the AdS/CFT correspondence, I will show that the BPS instanton equations governing such processes are equivalent to the three-dimensional Laplace equation, under an approximation which is valid when the matrix size is large. I will further show that the solution which corresponds to a splitting process is not defined on R^3, but rather on a space which is constructed by stitching two R^3’s, in a manner analogues to the construction of Riemann surfaces. I will also show plots, constructed using explicit solutions to the Laplace equation, which capture explicitly the behaviours of membranes in the splitting processes. The talk will be based on arxiv:1508.03367, done in collaboration with Stefano Kovacs (Dublin IAS) and Yuki Sato (Chulalongkorn Univ., Bangkok).
Ryo Suzuki, ICTP-SAIFR
Superconformal bootstrap of N=4 Super Yang-Mills and average anomalous dimensions
Seminar room, Kenkyu honkan 3F
Correlation functions of a conformal field theory (CFT) can be constructed from two- and three-point functions. However, the planar four-point functions of a large Nc CFT cannot be recovered by the planar two- and three-points. We apply the superconformal block decomposition to the four-point functions of N=4 SYM, and extracted the non-planar information of multi-trace operators. In addition, we identified non-scalar superconformal primary fields which contribute to the OPE limit. This work is based on collaboration with Yusuke Kimura (OIQP).
Teppei Kitahara, Karlsruhe Institute of Technology
Recent progress on CP violation in K to pi pi decays in the SM and SUSY solution
Seminar Room, Kenkyu-honkan 3F Recent progress in the determination of hadronic matrix elements has revealed a tension between the measured value of epsilon’/epsilon, which quantifies direct CP-violation in K to pi pi decays, and the Standard-Model (SM) prediction. On the other hand, the standard analytic solution of the next-to-leading order (NLO) renormalization group (RG) evolution for the DeltaS = 1 Wilson coefficients suffers from several singularities. In the first part of this talk, we will introduce a singularity-free analytic solution of the RG evolution, and give a new prediction value of the epsilon’/epsilon in the SM at the NLO, which also implies the epsilon’ discrepancy. In the second part, we will show that it is possible to cure the epsilon’ discrepancy in the Minimal Supersymmetric Standard Model with squark masses above 3 TeV without overshooting epsilon. This solution exploits two features of supersymmetry, the possibility of large isospin-breaking contributions (enhancing epsilon’) and the Majorana nature of gluinos (permitting a suppression of epsilon). Our solution involves no fine-tuning of CP phases or other parameters.
Recent progress in the determination of hadronic matrix elements has revealed a tension between the measured value of epsilon’/epsilon, which quantifies direct CP-violation in K to pi pi decays, and the Standard-Model (SM) prediction. On the other hand, the standard analytic solution of the next-to-leading order (NLO) renormalization group (RG) evolution for the DeltaS = 1 Wilson coefficients suffers from several singularities. In the first part of this talk, we will introduce a singularity-free analytic solution of the RG evolution, and give a new prediction value of the epsilon’/epsilon in the SM at the NLO, which also implies the epsilon’ discrepancy. In the second part, we will show that it is possible to cure the epsilon’ discrepancy in the Minimal Supersymmetric Standard Model with squark masses above 3 TeV without overshooting epsilon. This solution exploits two features of supersymmetry, the possibility of large isospin-breaking contributions (enhancing epsilon’) and the Majorana nature of gluinos (permitting a suppression of epsilon). Our solution involves no fine-tuning of CP phases or other parameters.
This talk is based on
arXiv:1604.07400 and
arXiv:1607.06727.
Kaori Fuyuto, Saga Univ
Verifiability of electroweak baryogenesis in an extended Standard Model
Seminar room, Kenkyu honkan 3F
We discuss verifiability of electroweak baryogenesis in an extended Standard Model, where an extra Higgs doublet, a real singlet and electroweak-interacting fermions are added. In the model, while the real singlet plays a role in having first order electroweak phase transition, a new CP-violating source is supplied by interactions between bubble walls and new fermions. It is shown that the parameter region for the successful BAU can be verified by Higgs physics and electric dipole moments of electron and nucleons in near future.
Kazuki Sakurai, Durham Univ.
Search for Sphalerons: LHC vs. IceCube
Meeting room 1, Kenkyu honkan 1F
In a recent paper, Tye and Wong (TW) have argued that sphaleron-induced transitions in high-energy interactions should be enhanced compared to previous calculations, based on a construction of a Bloch wave function in the periodic sphaleron potential and the corresponding pass band structure. In this talk, I present our resent work studying future prospects of observing sphaleron transitions at high energy hadron colliders and IceCube, based on TW results. I first discuss the production rate and possible signatures of the sphaleron-induced processes at high energy hadron colliders. We recast the early ATLAS Run-2 search for microscopic black holes to constrain the rate of sphaleron transitions at 13 TeV LHC. In the second half of the talk, I will discuss the possibility of observing sphaleron transitions induced by cosmogenic neutrinos at IceCube. I calculate the sphaleron event rate at IceCube and discuss the signature of such events. Finally I compare the performance of the sphaleron searches at the LHC and IceCube and find complementarity of these experiments.
Wen Yin, Tohoku Univ.
Novel Approach to Fine-tuned Supersymmetric Standard Models, and the Explanation of the Muon Anomalous Magnetic Dipole Moment Anomaly
Meeting room 1, Kenkyu honkan 1F, slides (kek.jp only) I will propose an analyzing method for supersymmetric standard models with some amount of fine tuning. Applying this method to a non-universal Higgs masses model, I will show a new typical region and the explanation of the muon anomalous magnetic dipole moment (muon g-2) within its 1σ error. In particular, the explanation of the muon g-2 anomaly has been considered to be difficult in this model due to the heavy stop masses required by the measured SM Higgs boson mass and the condition of the universal sfermion mass at the GUT scale. [arXiv:1606.04953]
I will propose an analyzing method for supersymmetric standard models with some amount of fine tuning. Applying this method to a non-universal Higgs masses model, I will show a new typical region and the explanation of the muon anomalous magnetic dipole moment (muon g-2) within its 1σ error. In particular, the explanation of the muon g-2 anomaly has been considered to be difficult in this model due to the heavy stop masses required by the measured SM Higgs boson mass and the condition of the universal sfermion mass at the GUT scale. [arXiv:1606.04953]
I will also propose a new simple set up of the MSSM, where at the GUT scale, only the Higgs sector is coupled with SUSY breaking. All the other sparticles obtain masses from the Higgs sector via RG running and superWeyl anomaly. The sfermion spectra are typical where the first two generation sfermions are as light as ~1TeV with anomaly induced gaugino masses, while the third ones, Higgsino and A-Higgs are heavier than O(10)TeV. I will discuss about the phenomenology of this set up, such as the explanation of the muon g-2 anomaly, the alleviation of gravitino/flavor problem and also other interesting possibilities.
Taro Kimura, Keio University
Boundary condition analysis of topological insulators
Meeting room 1, Kenkyu honkan 1F, slides (kek.jp only)
Study of topological insulators and superconductors (topological phases of matter) is currently an active research area in condensed-matter physics. One of the most important aspects of them is the renowned relation between bulk and edge states, called the bulk/edge correspondence. The edge state, localized at the material boundary, is sensitive to a boundary condition definitely, but how the boundary condition affects the edge state has not been studied in a systematic way so far. We tackle this problem with a minimal model of topological insulator, and show boundary condition dependence of the edge state, in particular, its energy spectrum and wavefunction behavior. We also argue how such a generic boundary condition is realized in lattice models. This talk is based on a collaboration with K. Hashimoto and X. Wu (Osaka): [arXiv:1509.04676], [arXiv:1602.05577] and work in progress.
Masazumi Honda, Weizmann Institute
How to resume perturbative series in supersymmetric gauge theories
Meeting room 1, kenkyu honkan 1F, slides (kek.jp only) Perturbative series in quanum field theory is typically divergent.
Perturbative series in quanum field theory is typically divergent.
There is a standard method to resum divergent series called Borel resummation.
While perturbative series in typical field theory is expected to be non-Borel summable,
it is important to ask when perturbative series is Borel summable and if it is non-Borel summable,
what is a correct way to resum the perturbative series.
In my talk I first discuss that we can prove Borel summability of perturbative series
in 4d N=2 and 5d N=1 supersymmetric gauge theories with Lagrangians for various observables.
It turns out that exact results in these theories can be obtained by summing over the Borel resummations with every instanton number.
I also discuss perturbative series in general 3d N=2 supersymmetric Chern-Simons matter theory,
which is given by a power series expansion of inverse Chern-Simons levels.
We prove that the perturbative series are always Borel summable along imaginary axis.
It turns out that the Borel resummations along this direction are the same as exact results.
[PRL116,no.21,211601(2016) and arXiv:1604.08653]
Tomoya Kinugawa, ICRR, The University of Tokyo
Binary black hole remnants of First stars for the gravitational wave source
Meeting room 1, Kenkyu honkan 1F
Using our population synthesis code, we found that the typical chirp mass of binary black holes (BH-BHs) whose origin is the first star (Pop III) is ~30Msun with the total mass of ~60Msun so that the inspiral chirp signal as well as quasi normal mode (QNM) of the merging black hole are interesting targets of LIGO,VIRGO and KAGRA (Kinugawa et al.2014 and 2016). The detection rate of the coalescing Pop III BH-BHs is ~ 180 events/yr (SFR_p/(10^{-2.5} Msun /yr/Mpc^3))*([f_b/(1+f_b)]/0.33)*Err_sys in our standard model where SFR_p, f_b and Err_sys are the peak value of the Pop III star formation rate, the binary fraction and the systematic error with Err_sys=1 for our standard model, respectively. Furthermore, We found that the chirp mass has a peak at ~30Msun in most of parameters and distribution functions (Kinugawa et al.2016). This result predicted the gravitational wave events like GW150914 and LIGO paper said ‘recently predicted BBH total masses agree astonishingly well with GW150914 and can have sufficiently long merger times to occur in the nearby universe (Kinugawa et al. 2014)’ (Abbot et al. ApJL 818,22 (2016)). Nakano, Tanaka & Nakamura 2015 show that if S/N of QNM is larger than 35, we can confirm or refute the General Relativity more than 5 sigma level. In our standard model, the detection rate of Pop III BH-BHs whose S/N is larger than 35 is 3.2 events/yr (SFR_p/(10^{-2.5}Msun/yr/Mpc^3))*([f_b/(1+f_b)]/0.33)* Err_sys. Thus, there is a good chance to check whether GR is correct or not in the strong gravity region and to check indirectly the existence of Pop III massive stars by gravitational wave.
Takahiro Tanaka, Kyoto University
Gravitational waves as a new probe of physics
Seminar room, Kenkyu honkan 3F, slides (kek.jp only)
