George Knee, NTT Basic Research Laboratories
Is weak-value amplification useful for metrology?
Seminar room, Kenkyu honkan 3F
Weak value amplification is a technique combining both strong and weak quantum measurements which is gathering increased interest both theoretically and experimentally. The surprising effect arises when a weak measurement, where a quantum coherent measuring device is only weakly coupled to the system of interest, is followed by a strong measurement. Rarely, the measuring device can respond in an unusually energetic manner. I will discuss some approaches in statistical estimation theory, which may help to decide whether this effect can be exploited to increase the performance of quantum sensors.
Thorsten Feldmann, U Siegen
Light-cone distribution amplitude of the B-meson
Meeting room 3, Kenkyu honkan 1F
Light-cone distribution amplitudes (LCDAs) for B-mesons in heavy-quark effective theory (HQET) provide one of the essential non-perturbative inputs entering QCD factorization theorems for exclusive B-decays. In this talk, I show how to derive the eigenfunctions of the Lange-Neubert evolution equation which governs the behaviour of the B-meson LCDAs under a change of renormalization scale. The spectrum of the LCDA with respect to these eigenfunctions defines a “dual” function which renormalizes multiplicatively. In terms of these dual functions, renormalization-group improved factorization formulas take a very simple form. I also report on how to implement perturbative constraints from the operator product expansion in HQET within the new formalism.
Stefan Recksiegel, Technische Universitat Munchen
Using dimensional analysis as a measure of fine tuning
Meeting room 1, Kenkyu honkan 1F
When studying models of New Physics, usually many points in the parameter space of the model violate existing experimental constraints. We show that the fractal dimension of that part of parameter space that satisfies those constraints is a good measure of fine tuning. We introduce the concept of fractal dimensions, use a toy model to show that the fractal dimension measures fine tuning and then show examples from several models of New Physics.
Andrew Akeroyd, University of Southampton
Decay of charged Higgs bosons into charm and bottom quarks in multi-Higgs doublet models
Meeting room 1, Kenkyu honkan 1F
A scalar particle has been discovered at the Large Hadron Collider (LHC), but it is not yet known if this particle corresponds to the Higgs boson of the Standard Model or if it is the first of many Higgs bosons which are waiting to be discovered. Higgs bosons with electric charge (“charged Higgs bosons” or “charged scalars”) are predicted in many extensions of the Standard Model. Searches for such particles are being carried out at the LHC, in particular in the decays of the top quark, and these searches assume that two specific decay modes of the charged Higgs boson are dominant: In this talk I show that a third decay mode, into charm and bottom quarks, can be dominant in models with more than two Higgs isospin doublets. So far there has been no dedicated search for this decay to charm and bottom quarks at the LHC, but it could readily be performed as an extension of an ongoing search which assumes that the charged Higgs boson decays into a charm quark and a strange quark.
Francesco Knechtli, University of Wuppertal
Non-perturbative Gauge-Higgs Unification on the Lattice
Meeting room 1, Kenkyu honkan 1F Gauge-Higgs Unification models are theories where the Higgs field is identified with some of the extra-dimensional components of the gauge field.
Gauge-Higgs Unification models are theories where the Higgs field is identified with some of the extra-dimensional components of the gauge field.
One motivation for these models is that the extra-dimensional gauge symmetry protects the Higgs potential from divergences in the ultra-violet cut-off.
Perturbative studies indicate that fermions are necessary to trigger the Higgs mechanism. Given the non-renormalizability of gauge theories in dimensions higher than four, we study non-perturbatively the simplest model which is a five-dimensional SU(2) gauge theory on a orbifold.
The starting point is the formulation on an anisotropic Euclidean lattice.
Results using a semi-analytic mean-field expansion and Monte Carlo simulations show that the Higgs mechanism takes place without fermions and support an alternative view of the lattice orbifold as a five-dimensional bosonic superconductor.
Tsunehide Kuroki, Nagoya U
SUSY breaking by nonperturbative dynamics in a matrix model for 2D type IIA superstrings
Seminar room, Kenkyu honkan 3F
We explicitly compute nonperturbative effects in a supersymmetric double-well matrix model corresponding to two-dimensional type IIA superstring theory on a nontrivial Ramond-Ramond background. We analytically determine the full one-instanton contribution to the free energy and one-point function, including all perturbative fluctuations around the one-instanton background. The leading order two-instanton contribution is determined as well. We see that supersymmetry is spontaneously broken by instantons, and that the breaking persists after taking a double scaling limit which realizes the type IIA theory from the matrix model. The result implies that spontaneous supersymmetry breaking occurs by nonperturbative dynamics in the target space of the IIA theory. We also discuss recent progress in summing up all instanton contributions using knowledge of random matrix theory
Masakiyo Kitazawa, Osaka U
Thermal fluctuations in relativistic heavy ion collisions
Seminar room, Kenkyu honkan 3F
Event-by-event fluctuations of conserved charges in relativistic heavy ion collisions are useful observables to investigate primordial thermodynamics of the hot medium generated by the collisions. In particular, they are promising observables to investigate the global structure of QCD phase diagram in experiments, and have been actively measured in the beam-energy scan program at RHIC. In this talk, I will give a review on the present status of the experimental measurement of the fluctuations observables. I will also explian why the fluctuations are interesting and important observables. Some new methods to use these observables more efficiently will also be discussed.
Philipp Gubler, RIKEN
How does the measurement of the phi-meson mass shift in nuclear matter constrain the strangeness content of the nucleon?
Seminar room, Kenkyu honkan 3F In this seminar, I will present our latest results of our study on the behavior of the phi-meson at finite density [1], which makes use of a QCD sum rule approach in combination with the maximum entropy method [2]. As earlier works have already shown, we find a strong correlation between a possible mass shift of the phi-meson in nuclear matter and the strangeness content of the nucleon, which is proportional to the strange sigma term, sigma_{sN}. In contrast to other studies, we however find that, depending on the value of sigma_{sN}, the phi-meson could receive both a positive or negative mass shift at nuclear matter density. I will discuss the relevance of our results for the interpretation of the E325 experiment, which was performed at KEK and for the future E16 experiment to be carried out at the J-PARC facility.
In this seminar, I will present our latest results of our study on the behavior of the phi-meson at finite density [1], which makes use of a QCD sum rule approach in combination with the maximum entropy method [2]. As earlier works have already shown, we find a strong correlation between a possible mass shift of the phi-meson in nuclear matter and the strangeness content of the nucleon, which is proportional to the strange sigma term, sigma_{sN}. In contrast to other studies, we however find that, depending on the value of sigma_{sN}, the phi-meson could receive both a positive or negative mass shift at nuclear matter density. I will discuss the relevance of our results for the interpretation of the E325 experiment, which was performed at KEK and for the future E16 experiment to be carried out at the J-PARC facility.
If time allows, I will also briefly describe a few possible other applications of our method, such as investigating the behavior of in hadrons in a magnetic field or the study of some basic properties of the unitary fermi gas.
[1] P. Gubler and K. Ohtani, arXiv:1404.7701 [hep-ph].
[2] P. Gubler and M. Oka, Prog. Theor. Phys. 124, 995 (2010), arXiv:1005.2459 [hep-ph].
Roberto Emparan, University of Barcelona, YITP
The large D limit of General Relativity
Meeting room 1, Kenkyu honkan 1F
General Relativity is an old theory but its dynamics remains difficult to solve and understand, in particular when strongly-gravitating objects such as black holes are involved. Although at first sight it may seem an odd idea, I will argue that it is actually quite natural to investigate the properties of this theory and its black holes in the limit in which the number of spacetime dimensions D grows to infinity. The gravitational field localizes very strongly near the black hole horizons, which simplifies dramatically the description of their interactions and allows efficient calculational approaches in an expansion in 1/D. There are also hints that this limit may lead to a reformulation of the theory in terms of low-dimensional strings.
Yuji Omura, Nagoya University
Study on two-Higgs-doublet models (with gauged U(1) symmetry)
Meeting room 1, Kenkyu honkan 1F
