セミナー

Gerco Onderwater, Groningen U

Lepton Anomalies @ LHCb and elsewhere

Room 345, 4 go-kan
There is a wealth of experimental results questioning the deep-rooted assumption of lepton universality in flavour-changing interactions, while at the same time the large LHC experiments, ATLAS and CMS, do not see clear signals of New Physics. Recently several flavour anomalies were reported by the LHCb collaboration and there is the long standing discrepancy of the anomalous magnetic moment of the muon. At the same time there are ever-more impressive limits on charged lepton flavour violation. A comprehensive overview of how these results were obtained will be presented and their interconnections will be highlighted.

Ryo Yoshiike, Kyoto University

Role of axial anomaly and nesting in the inhomogeneous chiral phase

Meeting room 1, Kenkyu honkan 1F
Recently inhomogeneous chiral phase (iCP) has been expected to appear in the moderate density region in the QCD phase diagram, where chiral condensate is spatially modulating. It has been known that axial anomaly and nesting play important roles for iCP. Using the Gross-Neveu models in 1+1 dimensions, we shall discuss axial anomaly and nesting from two different points of view:one is inhomogeneous chiral transition and the other is the Ferrel-Fulde-Larkin-Ovchinnikov state in superconductivity, which are closely related to each other by way of duality.

Rainer Sommer, DESY

How strong are the strong interactions

Meeting room 1, Kenkyu honkan 1F
The ALPHA Collaboration has computed one of the most elusive fundamental parameters of Nature: the strong coupling. It governs the interactions of quarks and gluons. At high energies, such as the ones reached at the Large Hadron Collider (LHC) at CERN, many processes can be computed in terms of a Taylor series in this coupling. A precise input value for these series is thus essential to make best use of the accelerator. We have “simulated” QCD, the fundamental theory of the strong interactions, over a large range of energy scales in order to extract the coupling at LHC energies. The experimental input which is presently best suited to minimize the total uncertainty is, surprisingly, the weak decay rate of Pions and Kaons. We explain how our work sets a new standard in the determination of the strong coupling.

Takahiro Doi, Quantum Hadron Physics Laboratory, Nishina Center, RIKEN

Lattice QCD study for relation between quark-confinement and chiral symmetry breaking

Meeting room 1, Kenkyu honkan 1F
Both quark-confinement and chiral symmetry breaking are important non-perturbative phenomena in low-energy QCD. The motivation in this study is to investigate the relation between them. To that end, we derive some analytical relations between the Polyakov loop and the eigenmodes of the Dirac operator on a lattice. Those formulae suggest no direct one-to-one correspondence between quark-confinement and chiral symmtery breaking in QCD.

Yasuyuki Hatsuda, Rikkyo University

Borel resummation and S-duality in SL(2) Chern-Simons theory

Meeting room 3, Kenkyu honkan 1F
I will talk about an S-duality in SL(2) Chern-Simons theory. A perturbative semiclassical expansion does not have this symmetry, but its Borel resummation turns out to recover the exact S-dual symmetry.

Massimo Passera, INFN Padova

Measuring the leading hadronic contribution to the muon g-2 via muon-electron scattering

Seminar room, Kenkyu honkan 3F
I will present a recent proposal to determine the leading hadronic contribution to the muon g-2 via the measurement of the running of the electromagnetic coupling constant in the space-like region, by scattering high-energy muons on atomic electrons of a low-Z target.

Varun Sethi, University of Delhi

Finite Temperature Corrections to Tachyon Mass in Intersecting D-branes and Stacks of D-branes

Meeting room 1, Kenkyu honkan 1F, slides (kek.jp only)
In arXiv:1104.2843, a microscopic top-down model of a holographic superconductor is constructed using two intersecting D8-branes in the bulk in D4-brane background. This is a non-BPS configuration which has tachyons in its spectrum signaling instability of the system. This instability has been proposed to be the bulk analogue of the BCS instability in the boundary theory in 1104.2843. Our aim is to study a similar simplified system at finite temperature and evaluate the transition temperature. We thus consider a system of two intersecting D3 -branes in flat background, we compute one-loop finite temperature correction to tachyon two-point amplitude and find, numerically, the transition temperature at which effective mass-squared of the tachyon becomes zero. We further extend the calculation of tachyon two-point amplitude to the case of intersecting stacks of D3-branes.

Seiji Terashima, Yukawa Institute for Theoretical Physics

AdS/CFT Correspondence in Operator Formalism

Meeting room 3, Kenkyu honkan 1F
In this paper we study the AdS/CFT correspondence in the operator formalism without assuming the GKPW relation. We explicitly show that the low energy spectrum of the large N limit of CFT, which is realized by a strong coupling gauge theory, is identical to the spectrum of the free gravitational theory in the global AdS spacetime under some assumptions which are expected to be valid. Thus, two theories are equivalent for the low energy region under the assumptions. Using this equivalence, the bulk local field is constructed and the GKPW relation is derived.

Wen Yin, IHEP Chinese Academy of Sciences

Higgs-Anomaly Mediation: a simple setup with interesting phenomena and flavor safety

Meeting room 1, Kenkyu honkan 1F 
We consider a simple setup, called Higgs-Anomaly mediation, where all the multiplets in the MSSM except for the Higgs multiplets are sequestered from SUSY breaking, but the Higgs multiplets couple to through Planck-suppressed operators. In this setup, the splitting mass spectra of squarks and sleptons are generated through radiative corrections: anomaly mediation and a kind of Higgs mediation. Despite the stop masses greater than order 10 TeV favored by the measured mass of the Higgs boson, sfermions in first two generations can be sufficiently light to be searched for and tested in the LHC, and affect low energy phenomena in ground-based experiments. There are viable regions explaining muon g-2 anomaly, and bottom-tau and top-bottom-tau Yukawa unifications. These regions are testable from the viewpoint of collider experiments. Surprisingly, despite the splitting mass spectra, there are suppressed flavor-violating processes. In fact, the contribution to epsilon_K is constrained most severely. However, we show that this contribution is at most around 20% of the experimental value and is safely within the theoretical uncertainty of the SM.

Kazuki Sakurai, University of Warsaw

Natural and Unnatural SUSY in light of Proton Decay and Gauge Unification

Meeting room 1, Kenkyu honkan 1F
I present the recent study on natural and unnatural SUSY in light of the proton decay and gauge unification. We show that the low energy SUSY mass spectrum is linked to the proton decay via the unification scale, and future nucleon decay experiments will provide a non-trivial upper bound on the superpartner masses. We also show that the mirage mediation provides a consistent picture of natural SUSY. For unnatural SUSY, we present a systematic study on split SUSY and predict a unique spectrum, which could be around the corner of discovery.

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