arXiv subjects

Mahiko Suzuki

Publications and source records attributed to Mahiko Suzuki.

15 recordsLinked to original sources

arXiv2017

Inevitable emergence of composite gauge bosons

A simple theorem is proved: When a gauge-invariant local field theory is written in terms of matter fields alone, a composite gauge boson or bosons must be formed dynamically. The theorem results from the fact that the Noether current vanishes in such theories. The proof is carried out by use of the charge-field algebra at equal time in the Heisenberg picture together with the well-established analyticity of the form factor of the current. While there is no need of diagram calculation for the proof, we demonstrate in the leading 1/N expansion of the existing models what the theorem means in diagrams and how the composite gauge boson emerges.

hep-ph↗

arXiv2016

Composite gauge-bosons made of fermions

We construct a class of Abelian and non-Abelian local gauge theories that consist only of matter fields of fermions. The Lagrangian is compact and local without containing an auxiliary vector field nor a subsidiary condition on the matter fields. Because of the special structure, this Lagrangian can be extended to non-Abelian gauge symmetry only in the case of SU(2) doublet matter fields. We carry out explicit dynamical computation in the leading 1/N order to show that massless spin-one bound states appear with the correct gauge coupling. Our diagram calculation exposes the dynamical features that cannot be explored in the formal auxiliary vector-field trick. For instance, it shows that the s-wave fermion-antifermion interaction alone cannot form the bound gauge-bosons; the fermion-antifermion pairs must couple to the d-wave state too. One feature common to our class of Lagrangian is that the Noether current does not exist. Therefore it evades possible conflict with the no-go theorem of Weinberg and Witten on formation of the non-Abelian gauge bosons.

hep-th↗

arXiv2010

Approximate gauge symmetry of composite vector bosons

It can be shown in a solvable field theory model that the couplings of the composite vector bosons made of a fermion pair approach the gauge couplings in the limit of strong binding. Although this phenomenon may appear accidental and special to the vector boson made of a fermion pair, we extend it to the case of bosons being constituents and find that the same phenomenon occurs in more an intriguing way. The functional formalism not only facilitates computation but also provides us with a better insight into the generating mechanism of approximate gauge symmetry, in particular, how the strong binding and global current conservation conspire to generate such an approximate symmetry. Remarks are made on its possible relevance or irrelevance to electroweak and higher symmetries.

hep-ph↗

arXiv2008

Inelastic final-state interaction

The final-state interaction in multichannel decay processes is sytematically studied with application to B decay in mind. Since the final-state inteaction is intrinsically interwoven with the decay interaction in this case, no simple phase theorem like "Watson's theorem" holds for experimentally observed final states. We first examine in detail the two-channel problem as a toy-model to clarify the issues and to remedy common mistakes made in earlier literature. Realistic multichannel problems are too challenging for quantitative analysis. To cope with mathematical complexity, we introduce a method of approximation that is applicable to the case where one prominant inelastic channel dominates over all others. We illustrate this approximation method in the amplitude of the decay B to pi K fed by the intermediate states of a charmed meson pair. Even with our approximation we need more accurate information of strong interactions than we have now. Nonethless we are able to obtain some insight in the issue and draw useful conclusions on general fearyres on the strong phases.

hep-ph↗

arXiv2006

Partial waves of baryon-antibaryon in three-body B meson decay

The conspicuous threshold enhancement has been observed in the baryon-antibaryon subchannels of many three-body B decay modes. By examining the partial waves of baryon-antibaryon, we first show for B- -->pp-bar K- that the pK- angular correlation rules out dominance of a single pp-bar partial wave for the enhancement, for instance, the resonance hypothesis or the strong final-state interaction in a single channel. The measured pK- angular correlation turns out to be opposite to the naive expectation of the short-distance picture. We study the origin of this reversed angular correlation in the context of the pp-bar partial waves and argue that NN-bar bound states may be the cause of this sign reversal. Dependence of the angular correlation on the pp-bar invariant mass is very important to probe the underlying problem from the experimental side.

hep-ph↗

arXiv2005

The X(3872) boson: Molecule or charmonium

It has been argued that the mystery boson X(3872) is a molecule state consisting of primarily D0-D0*bar + D0bar-D*0. In contrast, apparent puzzles and potential difficulties have been pointed out for the charmonium assignment of X(3872). We examine several aspects of these alternatives by semiquantitative methods since quantitatively accurate results are often hard to reach on them. We find that some of the observed properties of X(3872), in particualr, the binding and the production rates are incompatible with the molecule interpretation. Despite puzzles and obstacles, X(3872) may fit more likely to the excited triplet P_1 charmonium than to the molecule after mixing of cc-bar with DD*-bar +Dbar-D* is taken into account. One simple experimental test is pointed out for distinguishing between a charmonium and an isospin-mixed molecule in the neutral B decay.

hep-ph↗

arXiv2005

Baryon helicity in B decay

The unexpectedly large transverse polarization measured in the B-to-phi K* decay poses the question whether it is accounted for as a strong interaction effect or possibly points to a hidden nonstandard weak interaction. We extend here the perturbative argument to the helicity structure of the two-body baryonic decay and discuss qualitatively on how the baryonic B decay modes might help us in understanding the issue raised by the B-to-VV decays. We find among others that the helicity +1/2 amplitude dominates in the leading order in the B (b-bar q) decay and that the dominant amplitude is sensitive to the right-handed penguin interaction.

hep-ph↗

arXiv2004

Broken SU(3) antidecuplet for $Θ^+$ and $Ξ_{3/2}$

If the narrow exotic baryon resonances $Θ^+(1540)$ and $Ξ_{{3/2}(1862)$ are members of the $J^P = {1/2}1/2^+$ antidecuplet with $N^*(1710)$, the octet-antidecuplet mixing is required not only by the mass spectrum but also by the decay pattern of $N^*(1710)$. This casts doubt on validity of the $Θ^+$ mass prediciton by the chiral soliton model. While all pieces of the existing experimental information point to a small octet-antidecuplet mixing, the magnitude of mixing required by the mass spectrum is not consistent with the value needed to account for the hadronic decay rates. The discrepancy is not resolved even after the large experimental uncertainty is taken into consideration. We fail to find an alternative SU(3) assignment even with different spin-parity assignment.

hep-ph↗

arXiv2003

On the hidden charm state at 3872 MeV

We discuss some puzzling aspects of the narrow hidden charm resonance that was recently discovered by the Belle Collaboration at mass 3872 MeV. In order to determine its quantum numbers, a crucial piece of information is the spin of the dipion in the decay final state pi^+pi^-J/psi. We give the angular distributions and correlations of the final particles in the decay which will give this information about the nature of this resonance.

hep-ph↗

arXiv2001

An obvious isospin breaking correction to epsilon' of kinematical origin

Isospin breaking correction to the $ΔI = {1/2}$ decay of $K\toππ$ generates a large enough contribution to $ε'$ through an induced $ΔI = {3/2}$ amplitude in $K_L$ decay. Aside from the $π$-$η$ and $π$-$η'$ mixing contributions, there is a correction of kinematical origin due to the final-state $π^{\pm}$-$π^0$ mass difference, which is unambiguously calculable from the low-energy off-shell behavior of the $K\toππ$ amplitude. This correction to $ε'$ reduces the isospin breaking parameter $Ω_{IB}$ by 0.06, which is nearly one half of the $π$-$η$ mixing effect computed with chiral Lagrangians to $O(p^2)$.

hep-ph↗

arXiv2001

Extrapolation of K to ππdecay amplitude

We examine the uncertainties involved in the off-mass-shell extrapolation of the $K\rightarrow ππ$ decay amplitude with emphasis on those aspects that have so far been overlooked or ignored. Among them are initial-state interactions, choice of the extrapolated kaon field, and the relation between the asymptotic behavior and the zeros of the decay amplitude. In the inelastic region the phase of the decay amplitude cannot be determined by strong interaction alone and even its asymptotic value cannot be deduced from experiment. More a fundamental issue is intrinsic nonuniqueness of off-shell values of hadronic matrix elements in general. Though we are hampered with complexity of intermediate-energy meson interactions, we attempt to obtain a quantitative idea of the uncertainties due to the inelastic region and find that they can be much larger than more optimistic views portray.

hep-ph↗

arXiv1997

Final-State Interactions in Nonleptonic Weak Decays of D and B Mesons

We study final-state interactions in nonleptonic weak decays in statistical models by averaging over ensembles of strong interaction S-matrices. The models range from one with completely random strong interactions, which gives extensive mixing between physical states, to models with feeble final-state interactions, characterized by small phase shifts.

hep-ph↗

arXiv1995

General Classical Solutions of Nonlinear $σ$-Model and Pion Charge Distribution of Disoriented Chiral Condensate

We obtain the general analytic solutions of the nonlinear $σ$-model in $3+1$ dimensions as the candidates for the disoriented chiral condensate (DCC). The nonuniformly isospin-orientated solutions are shown to be related to the uniformly oriented ones through the chiral (axial) rotations. We discuss the pion charge distribution arising from these solutions. The distribution $dP/df=1/(2\sqrt{f})$ holds for the uniform solutions in general and the nonuniform solutions in the $1+1$ boost invariant case. For the nonuniform solution in $1+1$ without a boost-invariance and in higher dimensions, the distribution does not hold in the integrated form. However, it is applicable to the pions selected from a small segment in the momentum phase space. We suggest that the nonuniform DCC's may correspond to the mini-Centauro events.

hep-ph↗

arXiv1995

Isospin Coherence and Final-State Scattering of Disoriented Chiral Condensate

We examine the validity of the notion of the coherent state for pions and the quantum scattering effect in the final state of pion emission. When the number of particles is large, the effect caused by the small but finite mass difference between the neutral and charged pions can add up substantially in the quantum evolution of an initially coherent state. As a result, the states with quite different numbers of neutral or charged pions are essentially incoherent. The importance of the quantum scattering in the final-state isospin charge distribution of a disoriented chiral condensate (DCC) is investigated. We find that the scattering effect significantly reduces the spectacular Centauro and anti-Centauro events. The deformation of a charge distribution $dP/df$ predicted by the classical field theory is significant only for a DCC with the size of 10 fm or more.

hep-ph↗

arXiv1994

Signals of Disoriented Chiral Condensate

If a disoriented chiral condensate is created over an extended space-time region following a rapid cooling in hadronic or nuclear collisions, the misalignment of the condensate with the electroweak symmetry breaking can generate observable effects in the processes which involve both strong and electromagnetic interactions. We point out the relevance of the dilepton decay of light vector mesons as a signal for formation of the disoriented condensate. We predict that the decay ρ^0 to dileptons will be suppressed and/or the ρresonance peak widens, while the decay ωto dileptons will not be affected by the condensate.

hep-ph↗