Search results for "UNITARITY"
showing 10 items of 245 documents
Unitarity constraints on top quark signatures of Higgsless models
2005
We use conditions for unitarity cancellations to constrain the couplings of the top and bottom quarks to Kaluza-Klein modes in Higgsless models of electroweak symmetry breaking. An example for the mass spectrum of quark resonances in a theory space model is given and the implications for the collider phenomenology in the top sector are discussed, comparing to signatures of Little Higgs and strong electroweak symmetry breaking models.
The Bc → J/ΨKD weak decay and its relation with the D*s0(2317) resonance
2016
We study the influence of the D * s 0 (2317) + resonance in the decay B c → J/ψKD . In this process, we consider that the B c meson decays first into J/ψ and the quark pair cs , and then the quark pair hadronizes into DK or D s η components. The final state interaction, generating the D * s 0 (2317) + resonance, is described by the chiral heavy meson unitary approach. With the parameters chosen in order to match the pole position of the D * s 0 (2317) + , we obtain the DK invariant mass distribution of the decay B c → J/ψDK , and also the rate for B c → J/ψD * s 0 (2317). We predict the ratio of these two magnitudes. This decay mechanism has not been measured yet, and it would provide insig…
Rare decay modes of the neutral pion
1984
3 páginas, 2 figuras, 1 tabla.
Pion photoproduction and Compton scattering in quark models
2008
I review quark model studies for pion photoproduction and Compton scattering off nucleons. The important role of unitarity and electromagnetic gauge invariance is stressed.
Ds0*(2317)+in the decay ofBcintoJ/ψDK
2016
In this paper we study the relationship between the ${D}_{s0}^{*}(2317{)}^{+}$ resonance and the decay of the ${B}_{c}$ meson into $J/\ensuremath{\psi}DK$. In this process, the ${B}_{c}$ meson decays first into $J/\ensuremath{\psi}$ and the quark pair $c\overline{s}$, and then the quark pair hadronizes into $DK$ or ${D}_{s}\ensuremath{\eta}$ components, which undergo final state interaction. This final state interaction, generating the ${D}_{s0}^{*}(2317{)}^{+}$ resonance, is described by the chiral unitary approach. With the parameters which allow us to match the pole position of the ${D}_{s0}^{*}(2317{)}^{+}$, we obtain the $DK$ invariant mass distribution of the decay ${B}_{c}\ensuremath…
High-precision atomic mass measurements for a CKM unitarity test
2013
Abstract The Cabibbo–Kobayashi–Maskawa (CKM) quark-mixing matrix describes the transformation of quarks from weak-force eigenstates to mass eigenstates. The most contributing element in this matrix is the up-down matrix element V ud , derived in most precise way from the nuclear beta decays and in particular, from decays having superallowed 0 + → 0 + decay branch. What high-precision mass spectrometry community can offer are decay energies of such decays derived from parent–daughter mass differences, which are ideally, and in almost all cases, determined with Penning trap mass spectrometry directly from parent–daughter cyclotron frequency ratio. Typically frequency (and thus mass) ratios a…
Scalar ΛN and ΛΛ interactions within a chiral unitary approach
2008
We study the central part of the ΛN potential by considering the correlated and uncorrelated two-meson exchange besides the ω exchange contribution. The correlated two-meson is evaluated in a chiral unitary approach. We find that a short range repulsion is generated by the correlated two-meson potential which also produces an attraction in the intermediate distance region. The uncorrelated two-meson exchange produces a sizable attraction in all cases which is counterbalanced by ω exchange contribution.
Massive Spin One and Renormalizable Gauges
2015
For many decades of the last century, physicists were struggling to define consistent (renormalizable and unitarity preserving) models for spin-one massive particles (Proca fields). As we know, this was beautifully achieved by Weinberg, Salam and Glashow in 1967 when they proposed an electroweak unified theory which we now call the Standard Model. The electroweak symmetry breaking mechanism, among other things, generates mass terms for the W and Z bosons, while preserving renormalizability and unitarity. The longitudinal degrees of freedom of the massive spin-one particles are given by the Goldostone bosons. Choosing one gauge or another might seem just a matter of convenience and in most c…
The Crossing Symmetric Bethe-Salpeter Equation
1972
As you may recall from the lectures of Prof. Sand-has [1], in non-relativistic quantum theory,the scattering amplitude satisfies the Lippmann-Schwinger equation, $$T = V + V{G_o}T$$ (1) It can be explicitly shown that if V=V+, T satisfies the elastic unitarity relation, Im T=TT+.
Chiral dynamics of thepwave inK−pand coupled states
2002
We perform an evaluation of the p-wave amplitudes of meson-baryon scattering in the strangeness $S=\ensuremath{-}1$ sector starting from the lowest order chiral Lagrangians and introducing explicitly the ${\ensuremath{\Sigma}}^{*}$ field with couplings to the meson-baryon states obtained using SU(6) symmetry. The $N/D$ method of unitarization is used, equivalent, in practice, to the use of the Bethe-Salpeter equation with a cutoff. The procedure leaves no freedom for the p-waves once the s-waves are fixed and thus one obtains genuine predictions for the p-wave scattering amplitudes, which are in good agreement with experimental results for differential cross sections, as well as for the wid…