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Alfonso R. Zerwekh

Publications and source records attributed to Alfonso R. Zerwekh.

43 records · Page 3Linked to original sources
arXiv2004

Study of a Neutrino Mass Texture Generated in Supergravity with Bilinear R-Parity Violation

We study a particular texture of the neutrino mass matrix generated in supergravity with bilinear R-Parity violation. The relatively high value of $\tanβ$ makes the one-loop contribution to the neutrino mass matrix as important as the tree-level one. The atmospheric angle is nearly maximal, and its deviation from maximal mixing is related to the smallness of the ratio between the solar and atmospheric mass scales. There is also a common origin for the small values of the solar and reactor angles, but the later is much smaller due the large mass ratio between the lightest two neutrinos. There is a high dependence of the neutrino mass differences on the scalar mass $m_0$ and the gaugino mass $M_{1/2}$, but a smaller one of the mixing angles on the same sugra parameters. Measurements of branching ratios for the neutralino decays can give important information on the parameters of the model. There are good prospects at a future Linear Collider for these measurements, but a more detailed analysis is necessary for the LHC.

hep-ph↗
arXiv2002

Classical sum rules and spin correlations in photoabsorption and photoproduction processes

In this paper we study the possibility of generalizing the classical photoabsorption ($γa \to b c$) sum rules, to processes $b c \to γa$ and crossed helicity amplitudes. In the first case, using detailed balance, the sum rule is written as $\int_{ν_{th}}^\infty {\frac{dν}ν} KΔσ_{Born} (ν)=0$ where $K$ is a kinematical constant which depends only on the mass of the particles and the center of mass energy. For other crossed helicity amplitudes, we show that there is a range of values of $s$ and $t$ for which the differential cross section for the process $γb \to a c$ or $a c \to γb$ in which the helicities of the photon and particle $a$ have specific values, is equal to the differential cross section for the process in which one of these two helicities is reversed (parallel-antiparallel spin correlation).

hep-ph↗
arXiv2001

New Limits on the Color-Octet Technirho Mass from its Decay to Dijets

Recently has been shown that the physical (mass eigenstate) color-octet technirho does not couple to two gluons. In this letter we study how this result affects the presently accepted limits for the color-octet technirho mass obtained from the study of dijets production at the Tevatron. First we show that data from Tevatron Run 1b can not exclude any mass range. Finally, we obtain limits for the Tevatron Run II.

hep-ph↗
arXiv2001

Gauge Invariance, Color-Octet Vector Resonances and Double Technieta Production at the Tevatron

We show that the usual vector meson dominance method does not apply directly to the mixing of a color-octet vector boson (color-octet technirho) with the gluon because of gauge invariance. We propose a gauge invariant method where one works in a physical basis with mass eigenstate fields. As a result, we show that the physical technirho does not couple to two gluons, contrary to the general belief. Consequences for the production of a pair of color-octet, isosinglet technipions (technietas) at Fermilab is analysed by means of a simulation of the signal and background, including kinematical cuts. We find that the signal is too small to be observed.

hep-ph↗
arXiv1999

Tevatron Potential for Technicolor Search with Prompt Photons

We perform a detailed study of the process of single color octet isoscalar $η_T$ production at the Tevatron with $η_T \to γ+ g$ decay signature, including a complete simulation of signal and background processes. We determined a set of optimal cuts from an analysis of the various kinematical distributions for the signal and backgrounds. As a result we show the exclusion and discovery limits on the $η_T$ mass which could be established at the Tevatron for some technicolor models.

hep-ph↗
arXiv1998

Limits on a Strong Electroweak Sector from e^+ e^- -> 2gamma + missing E at LEP2

We study the process $e^+ e^- \to γγν\barν$ in the context of a strong electroweak symmetry breaking model, which can be a source of events with two photons and missing energy at LEP2. We investigate bounds on the model assuming that no deviation is observed from the Standard Model within a given experimental error.

hep-ph↗