相关论文: Z decays into light gluinos: a calculation based o…
In this talk, we discuss top-quark contributions to $ZZ$ production through gluon fusion at two loops. We use syzygies and modular arithmetic to compute the reductions to master integrals. In order to numerically evaluate the amplitude, we…
The ATLAS and CMS Collaborations reported that the observed number of Higgs boson decays into a $Z$ boson and a photon is $\mu = 2.2 \pm 0.7$ times higher than predicted by the Standard Model. Initially, this discrepancy was attributed to a…
We consider the phenomenology of the decay of a Z boson into a photon and a Kaluza-Klein excitation of the graviton in the ADD model. Using LEP data, we obtain an upper bound on the branching ratio corresponding to this process of ~10^-11.…
We study the production of a light gauge boson in $K^- \to \pi^- X$ decay, where the associated new charge current is not conserved. It is found that the process can be generated by the tree-level $W$-boson annihilation and loop-induced…
In an extension of the Standard Model with one compact extra dimension and N=1 supersymmetry, we compute the Higgs boson decay rate into two gluons, relevant to the Higgs production in hadronic collisions. We find that at one loop the decay…
The effective interaction for two neutrino, two photon coupling is used to find an approximate width for the decay of the Z boson into the nu nubar gamma gamma final state.
$Z \to \gamma \gamma$ decay amplitude is considered and proven to be zero due to properties of polarization vectors and Bose statistics. Triangular diagrams for a pseudoscalar $\to \gamma \gamma$ and $Z \to \gamma \gamma$ processes with…
We have examined the consequences of assuming the existence of a light scalar boson, weakly coupled to neutrinos, and not coupled to any other light fermions. For a range of parameters, we find that this hypothesis leads to the development…
We reconsider two classical proposals for the determination of the angle gamma of the unitarity triangle: B^\pm => chi_{c0} \pi^\pm => \pi^+\pi^-\pi^\pm and B_s => rho^0 K_S => \pi^+ \pi^- K_S. We point out the relevance, in both cases, of…
The amplitude for Higgs boson decay into two photons in a homogeneous and time-independent magnetic field is investigated by proper-time regularization in a gauge invariant manner and is found to be singular at large field values. The…
We present new calculations of the leading-order one-loop amplitude and the decay rate for $H\to \nu \bar{\nu} \gamma$ within the standard model, employing reduction to a set of basic Passarino-Veltman functions resulting in more concise…
The multi-sector SUSY breaking predicts the existence of pseudo-goldstino, which could couple more strongly to visible fields than ordinary gravitino. Then the lightest neutralino and chargino can decay into a pseudo-goldstino plus a…
We compute the top quark contribution to the two-loop amplitude for on-shell $Z$ boson pair production in gluon fusion, $gg \to ZZ$. Exact dependence on the top quark mass is retained. For each phase space point the integral reduction is…
We calculate the rates for inclusive hadronic decay of the three $\chi_{bJ}$ states into a pair of light bottom squarks as a function of the masses of the bottom squark and the gluino. We include color-singlet and color-octet…
The latest SLD results on light-quark fragmentation and tests of hadronisation models are presented
Searching for Z' bosons, predicted in GUT-inspired U(1)' gauge models and in the Sequential Standard Model, is one of the main challenges of the experiments carried out at the Large Hadron Collider. Such searches have so far focused on…
In view of the recent diboson resonant excesses reported by both ATLAS and CMS Collaborations, we suggest that a new weak singlet pseudo-scalar particle, $\eta_W$, may decay into two weak bosons while being produced in gluon fusion at the…
We present results for the production of a pair of on-shell Z bosons via gluon fusion. This process occurs both through the production and decay of the Higgs boson, and through continuum production where the Z boson couples to a loop of…
Higgs decays to Z boson pairs may be exploited to determine spin and parity of the Higgs boson, a method complementary to spin-parity measurements in Higgs-strahlung. For a Higgs mass above the on-shell ZZ decay threshold, a…
We calculate the $S$-matrix element for the Higgs boson decay to a $Z$-boson and a photon, $h\to Z\gamma$, at one-loop in the Standard-Model Effective Field Theory (SMEFT) framework and in linear $R_{\xi}$-gauges. Our SMEFT expansion…