arXiv subjects

U. Cotti

Publications and source records attributed to U. Cotti.

113 records · Page 7Linked to original sources

arXiv2001

Search for the Lepton Flavour Violating Higgs decay H --> tau mu at Hadron Colliders

We study the prospects to detect at hadron colliders the Lepton Flavour Violating Higgs decay H --> tau mu, which can reach substantial branching fractions in several extensions of the SM. Among them, the generic two higgs doublet model can be taken as a representative case where B.R.(H --> tau mu) can reach values of order 10^-1-10^-2. Bounds on the LFV factor kappa_{tau mu} of order 0.8-1.7 can be derived at 95% c.l. at Tevatron Run-2 with 4 fb^-1 for m_H = 110-150 GeV.

hep-ph↗

arXiv1999

Production of neutral and charged Higgs bosons of the MSSM at the future e-gamma colliders

A complete study for the production of neutral (h^0, H^0, A^0 (= ϕ^0_i)) and charged Higgs (H^\pm) bosons at electron-photon colliders is presented in the context of the minimal supersymmetric standard model. A particular choice of the non-linear R_ξgauge is used to evaluate the amplitudes of the reaction e-gamma --> e ϕ^0_i. The resulting cross section indicates that it will be possible to detect a signal from the neutral Higgs bosons for most regions of parameter space at the future linear colliders with \sqrt{s}=500 GeV through the reaction e gamma --> e ϕ^0_i. This reaction also offers the interesting possibility to measure the Higgs mass through the detection of the outgoing electron. The production of the charged Higgs boson through the reaction e gamma --> ν_e H^\pm$ has in general smaller values for the cross section, which seems more difficult to observe.

hep-ph↗

arXiv1999

Detection of Neutral MSSM Higgs Bosons at LEP-II and NLC

We study the possibility of detecting the neutral Higgs bosons predicted in the Minimal Supersymmetric Standard Model (h0, H0, A0), with the reactions e+ e- --> b b h0 (H0, A0), using the helicity formalism. We analyze the region of parameter space (m_A0-tan beta) where h0(H0, A0) could be detected in the limit when tan beta is large. The numerical computation is done for the energy which is expected to be available at LEP-II (sqrt{s} = 200 GeV) and for a possible Next Linear e+ e- Collider (sqrt{s}=500 GeV).

hep-ph↗

arXiv1998

Lepton mass generation and family number violation mechanism in the $SU(6)\otimes U(1)$ model

Lepton family number violation processes arise in the $SU(6)_L \otimes U(1)_Y$ model due to the presence of an extra neutral gauge boson, Z$'$, with family changing couplings, and due to the fact that this model demands the existence of heavy exotic leptons. The mixing of the standard Z with Z$'$ and the mixing of ordinary leptons with exotic ones induce together family changing couplings on the Z and therefore nonvanishing rates for lepton family number violation processes, such as $Z \to e \barμ$, $μ\to ee\bar{e}$ and $μ\to eγ$. Additional contributions to the processes $μ\to e γ$ and $μ\to ee \bar{e}$ are induced from the mass generation mechanism. This last type of contributions may compete with the above one, depending on the masses of the scalars which participate in the diagrams which generate radiatively the masses of the charged leptons. Using the experimental data we compute some bounds for the mixings parameters and for the masses of the scalars.

hep-ph↗

arXiv1997

Exact formulae for Higgs production through e gamma --> e H in the non-linear R_ξgauge

We study the production of the SM Higgs boson (H^0) at future e gamma colliders, through the reaction e gamma --> e H^0. The amplitude is evaluated using the non-linear R_ξgauge, which greatly simplifies the calculation. Complete analytical expressions for the amplitudes are presented, which include the contributions from 1-loop triangles "gamma gamma^* H^0" and "gamma Z^* H^0" as well as the W- and Z-boxes with their related $eeH^0$ triangle graphs. The resulting cross section for this mechanism indicates that it could be used to detect the Higgs signal and to test its properties.

hep-ph↗