118549701
Full $\mathcal{O}(\alpha)$ electroweak radiative corrections to $e^{+}e^{-} \rightarrow t \bar{t} \gamma$ with GRACE-Loop
We present the full $\mathcal{O}(\alpha)$ electroweak radiative corrections to the process $e^{+}e^{-} \rightarrow t \bar{t} \gamma$ at the International Linear Collider (ILC). The computation is performed with the help of the GRACE-Loop system. We present the total cross-section and the top quark forward–backward asymmetry (AFB) as a function of the center-of-mass energy and compare them with the process $e^{+}e^{-} \rightarrow t \bar{t}$. We find that the value of AFB in $t \bar{t} \gamma$ production is larger than AFB in $t\bar{t}$ production. It is an important result for the measurement of the top quark forward–backward asymmetry at the ILC. Applying a structure function method, we also subtract the QED correction to gain the genuine weak correction in both the α scheme and the Gμ scheme ($\delta_{W}^{G_{\mu}}$). We obtain numerical values for $\delta_{W}^{G_{\mu}}$ which are changing from 2 % to −24 % when we vary the center-of-mass energy from 360 GeV to 1 TeV.
54183358
Calculation of Single Top Quark Production in Electron-Positron Scattering
15252744
Precise Numerical Evaluation of the Scalar One-Loop Integrals with the Infrared Divergence
We present a new approach for obtaining very precise integration results for infrared vertex and box diagrams, where the integration is carried out directly without performing any analytic integration of Feynman parameters. Using an appropriate numerical integration routine with an extrapolation method, together with a multi-precision lib rary, we have obtained integration results which agree with the analytic results to 10 digits even for such a very small photon mass as 10 150 GeV in the infrared vertex diagram.
123615884
Automation of loop amplitudes in numerical approach
Abstract An automatic calculating system GRACE-L1 of one-loop Feynman amplitude is reviewed. This system can be applied to 2 to 2-body one-loop processes. A sample calculation of 2 to 3-body one-loop amplitudes is also presented.
15312798
Monte Carlo Approach to Radiative Corrections in Bhabha Scattering
§ 1. lntroduction It has become a common understanding that detailed theoretical predictions for e+ e- experiments should include the radiative corrections with multi-photon contribu­ tion. A well-known example is the significant modification of the apparent cross section around the Z-boson pole at LEP.ll The study of inclusive processes with multi-photon emission has led some authors to propose several kinds of Monte Carlo generators. 2 l In a pre~ious paper 3 l we have reported a new method for the Monte Carlo generator of multi-photon and have shown some results obtained via a computer progam written for muon pair production in e+ e- annihilation. This is a QED version of the parton shower model which has been studied extensively in QCD. In this paper we generalize this method to the Bhabha scattering by employing essen­ tially the same algorithm as that for muon pair production. It will be convenient to summarize the main features of the algorithm to generate photons. We rely on the technique to sum up all the collinear singularities, which plays an essential role in the parton shower model. 4 J The present model is limited to the leading logarithmic approximation, though there is no difficulty in principle to include the next-to-leading corrections. 5 l This approximation is reasonable as the QED coupling a is very small compared with that in QCD. Another remarkable feature is that the transverse momentum distribution of produced photons is derived correctly once one imposes the four-momentum conservation at each of branching vertices. 4 l This is a consequence of the branching, e±--> e±y, being aprocess of 1--> 2 bodies.
122500053
A New Treatment of the Scaling Violation for Flavor Singlet Distribution Functions in QCD
In a previous paper (Ref. 1), hereafter, we call I) , Q 2 dependence for the parton distribution functions is extensively studied in the framework of Quantum Chromodynamics (QCD). In the paper I, "kernel function" method (method-2 of I) is proposed to calculate the Q 2 dependent parton distribution functions. This method is intended to obtain the exact solution of Altarelli-Parisi equations. 2 >3> The parton distribution functions f. (x, Q 2) in a hadron are*>
119426197
Nuclear wobbling motion and electromagnetic transitions
Abstract The nuclear wobbling motion is studied from a microscopic viewpoint. It is shown that the expressions not only of the excitation energy but also of the electromagnetic-transition rate in the microscopic RPA framework can be cast into the corresponding forms of the macroscopic rotor model. Criteria to identify the rotational band associated with the wobbling motion are given. Examples of realistic calculations are investigated and some theoretical predictions are presented.
16491530
Diabatic Mean-Field Description of Rotational Bands in Terms of the Selfconsistent Collective Coordinate Method
Diabatic description of rotational bands provides a clear-cut picture for understanding the back-bending phenomena, where the internal structure of the yrast band changes dramatically as a function of angular momentum. A microscopic framework to obtain the diabatic bands within the mean-field approximation is presented by making use of the selfconsistent collective coordinate method. Applying the framework, both the ground state rotational bands and the Stockholm bands are studied systematically for the rare-earth deformed nuclei. An overall agreement has been achieved between the calculated and observed rotational spectra. It is also shown that the inclusion of the double-stretched quadrupole-pairing interaction is crucial to obtain an overall agreement for the even-odd mass differences and the rotational spectra simultaneously.
118882824
Squark flavor mixing and CP asymmetry of neutral B mesons at LHCb
Abstract The CP violation of the neutral B meson is the important phenomenon to search for the new physics. The like-sign dimuon charge asymmetry observed by the D O Collaboration indicates the CP-violating new physics in the B s – B ¯ s mixing. On the other hand, LHCb observed the CP-violating asymmetry in B s 0 → J / ψ ϕ and B s 0 → J / ψ f 0 ( 980 ) , which is consistent with the SM prediction. However, there is still room for new physics of the CP violation. The CKMfitter has presented the allowed region of the new physics parameters taking account of the LHCb data. Based on these results, we discuss the effect of the squark flavor mixing on the CP violation in the B d and B s mesons. We predict asymmetries in the non-leptonic decays B d 0 → ϕ K S , B d 0 → η ′ K 0 , B s 0 → ϕ ϕ and B s 0 → ϕ η ′ .
8136589
Deviation from tri-bimaximal mixing and flavor symmetry breaking in a seesaw type A(4) model
Abstract We have studied the contribution of higher order corrections of the flavor symmetry breaking in the A 4 seesaw model with the supersymmetry. Taking account of possible higher dimensional mass operators, we predict the deviation from the tri-bimaximal lepton mixing for both normal hierarchy and inverted hierarchy of neutrino masses. We have found that the value of sin 2 2 θ 23 is larger than 0.96 and the upper bound of sin 2 θ 13 is 0.01. We have also examined the flavor changing neutral current of leptons from the soft SUSY breaking in slepton masses and A-terms within the framework of supergravity theory. Those magnitudes are enough suppressed to be consistent with experimental constraints.
9783573
S4 Flavor Symmetry of Quarks and Leptons in SU(5) GUT
We present an S4 flavor model to unify quarks and leptons in the framework of the SU(5) GUT. Three generations of 5-plets in SU(5) are assigned to 31 of S4, while the first and second generations of 10-plets in SU(5) are assigned to 2 of S4, and the third generation of 10-plets is assigned to 11 of S4. Right-handed neutrinos are also assigned to 2 for the first and second generations and to 11 for the third generation. By considering the vacuum alignments of relevant gauge singlet scalars, we predict the quark mixing as well as the tribimaximal mixing of neutrino flavors. In particular, the Cabbibo angle is predicted to be 15 ◦ in the limit of the vacuum alignment. We can improve the model to predict observed CKM mixing angles as well as the nonvanishing Ue3 of the neutrino flavor mixing. Subject Index: 140, 154