arXiv subjects
Publications and source records attributed to Yoshimasa Kurihara.
In this comment we show that the experimental results for a universally valid uncertainty relation in ref.[J. Erhart et al. Nat. Phys.(2012)10.1038/nphys2194]cannot be justified. The experiments cannot be recognized to establish a violation of the Heisenberg-type uncertainty relation suggested by Ozawa[Phys. Lett. A318(2003)21, Phys. Rev. A67(2003)042105].
We studied the feasibility of measurement of Higgs pair creation in a gamma gamma collider. We found the optimum collision energy is around 270 GeV from the sensitivity study with Higgs boson mass of 120 GeV/c^2. Main backgrounds are gamma gamma to WW, gamma gamma to ZZ, and gamma gamma to bbbb at the optimum collision energy. The preliminary analysis shows HH could be observed with the statistical significance of about 5 sigma when we chose correct assignment of a track by using color singlet information.
The initial-state jet matching method introduced in our previous studies has been applied to the event generation of single $W$ and $Z$ production processes and diboson ($W^{+}W^{-}$, $WZ$ and $ZZ$) production processes at hadron collisions in the framework of the GR@PPA event generator. The generated events reproduce the transverse momentum spectra of weak bosons continuously in the entire kinematical region. The matrix elements (ME) for hard interactions are still at the tree level. As in previous versions, the decays of weak bosons are included in the matrix elements. Therefore, spin correlations and phase-space effects in the decay of weak bosons are exact at the tree level. The program package includes custom-made parton shower programs as well as ME-based hard interaction generators in order to achieve self-consistent jet matching. The generated events can be passed to general-purpose event generators to make the simulation proceed down to the hadron level.
This paper describes applications of extrapolation for the computation of coefficients in an expansion of infrared divergent integrals. An extrapolation procedure is performed with respect to a parameter introduced by dimensional regularization. While this treats typical IR singularities at the boundaries of the integration domain, special care needs to be taken in cases where the integrand is singular in the interior of the domain as well as on the boundaries. A double extrapolation is devised for a class of massless vertex integrals. Quadruple precision results are presented, demonstrating high accuracy. The computations are supported by the use of general adaptive integration programs from the QUADPACK package, in iterated integrations with highly singular integrand functions.
We examine the single-photon processes in the frame work of supersymmetric models at future e+e- linear colliders. According to the recent experimental achievement, the optimistic polarization degrees for both electron and positron beams are taken into account to enhance the signal-to-noise ratio revealing the observable difference between supersymmetry breaking models. The minimal supergravity model and the minimal SU(5) grand unified model in gaugino mediation have been examined as examples. We see that after several years of accummulating data, the difference of the number of single-photon events between the two models received from the collider would be in excess of three times the statistical error, providing us the possibility to probe which model would be realized in nature. The result is well suitable for the future running of the International Linear Collider.
We studied a feasibility of measuring Higgs boson pair production in a Photon Linear Collider. The optimum energy of gamma gamma collision was estimated with a realistic luminosity distribution. We also discussed simulation study for detecting the signal against W boson pair backgrounds.
We investigate a single scalar neutrino production at the upgraded HERA with high luminosity in the framework of an R-parityviolating supersymmetric model. We find that the scalar neutrino with mass around 100GeV could be observed through investigating the multilepton production process e- p -> mu- sneutrino(tau) X -> mu- (e- mu+) X. The signal would be characterized by mu+ and e- with high transverse momentum as well as a sharp peak in the invariant mass M(e-,mu+) distribution.
The results on e+e- --> W+W- --> 4f(+gamma) obtained by different groups are compared with each other. Differences in the results for the total cross section of up to about 0.6% are traced back to different ways of implementing the double-pole approximation.
We present a study of single-W production ($e^+e^-\to e^-\barν_e W^+$) as a new probe of the anomalous couplings at the LEP energy region. We introduce simple cuts to separate the single-W process from W-pair production and have performed cross-section calculations using 4-fermion generator ``grc4f''. The cross-section of the single-W process is found to be large enough to detect at LEP experiments in the near future. In addition, a high sensitivity to the anomalous coupling of the $WWγ$ vertex is expected since the amplitude of the $WWγ$ diagram makes a dominant contribution in this process. We have found that the cross-section measurement of the single-W process in the LEP2 energy region can give complementary bounds on the anomalous couplings to those obtained from W-pair analysis.