Nova inscripció romana trobada a la ciutat de Valentia

Presentació d'una inscripció romana

Up Quark Masses from Down Quark Masses

The quark and charged lepton masses and the angles and phase of the CKM mixing matrix are nicely reproduced in a model which assumes SU(3)xSU(3) flavour symmetry broken by the v.e.v.'s of fields in its bi-fundamental representation. The relations among the quark mass eigenvalues, m_u/m_c \approx m_c/m_t \approx m^2_d/m^2_s \approx m^2_s/m^2_b \approx \Lambda^2_{GUT}/M^2_{Pl}, follow from the broken flavour symmetry. Large tan(beta) is required which also provides the best fits to data for the obtained textures. Lepton-quark grandunification with a field that breaks both SU(5) and the flavour group correctly extends the predictions to the charged lepton masses. The seesaw extension of the model to the neutrino sector predicts a Majorana mass matrix quadratically hierarchical as compared to the neutrino Dirac mass matrix, naturally yielding large mixings and low mass hierarchy for neutrinos.Comment: 11 pages, 1 figure. Published version: model improved, references adde

Poblamiento, explotación y entorno natural de los estadios alpinos y subalpinos del Pirineo central durante la primera mitad del Holoceno

Se presentan los resultados del estudio interdisciplinar realizado en Cova del Sardo y Abric de l'Estany de la Coveta I, ambos yacimientos en el entorno del Parque Nacional d'Aigüestortes i Estany de Sant Maurici. Estos se enmarcan en un amplio proyecto de prospección y excavación arqueológica entre las cabeceras de los valles de la Noguera Pallaresa y la Noguera Ribagorçana, en el Pirineo Central. Los estudios cubren la primera mitad del Holoceno y permiten documentar un impacto ambiental a nivel local durante la primera fase de ocupación neolítica, coincidente con el último Óptimo Climático. La presencia de cereales en el registro plantea la posibilidad de una agricultura local, no confirmada por los estudios polínicos. La ganadera fue probablemente la actividad principal. En las fases sucesivas se observa la recuperación del bosque cerrado, a la vez que se produce un deterioro climático y el patrón de ocupación y gestión del territorio cambia hacia una explotación de los pastos de alta montaña y los lagos, y bases de circos de las cabeceras de las cuencas secundarias. El estudio paleoecológico de contextos arqueológicos ha resultado de gran ayuda para la comprensión de fenómenos locales de impacto sobre el entorno como resultado de actividades económicasThis paper presents the results of the studies undergo at the Cova del Sardo and Abric de l'Estany de la Coveta I, two archaeological sites placed in the National Park of Aigüestortes and Estany de Sant Maurici. Both sites have been object of multiproxy analyses inside a long-term research program in archaeology that promotes surface surveys and excavations in the head of Noguera Pallaresa and Noguera Ribagorçana basins, in the Central Southern Pyrenees. The studies shown different variables that suggest an anthropogenic impact on the vegetation during the first half of the Neolithic occupation at Cova del Sardo, that took place during the Holocene Climatic Optimum. The presence of cereals seeds in two Neolithic phases suggests the possibility of some kind of local agriculture, although this hasn't been confirmed by pollen studies. Probably livestock it was the main economic activity in this site. In latter Neolithic phases at Cova del Sardo a recovery of a closed forest can be seen, while there is a climatic deterioration. Paradoxically, at this moment the occupation and exploitation pattern turns to a major emphasis towards the alpine pastures, with little camps around the lakes and glacial cirques just at the beginning of secondary basins. The palaeoecological study of archaeological contexts is very helpful to understand the local phenomena of environmental impact because of economic activitie

An SO(10) Grand Unified Theory of Flavor

We present a supersymmetric SO(10) grand unified theory (GUT) of flavor based on an $S_4$ family symmetry. It makes use of our recent proposal to use SO(10) with type II seesaw mechanism for neutrino masses combined with a simple ansatz that the dominant Yukawa matrix (the {\bf 10}-Higgs coupling to matter) has rank one. In this paper, we show how the rank one model can arise within some plausible assumptions as an effective field theory from vectorlike {\bf 16} dimensional matter fields with masses above the GUT scale. In order to obtain the desired fermion flavor texture we use $S_4$ flavon multiplets which acquire vevs in the ground state of the theory. By supplementing the $S_4$ theory with an additional discrete symmetry, we find that the flavon vacuum field alignments take a discrete set of values provided some of the higher dimensional couplings are small. Choosing a particular set of these vacuum alignments appears to lead to an unified understanding of observed quark-lepton flavor: (i) the lepton mixing matrix that is dominantly tri-bi-maximal with small corrections related to quark mixings; (ii) quark lepton mass relations at GUT scale: $m_b\simeq m_{\tau}$ and $m_\mu\simeq 3 m_s$ and (iii) the solar to atmospheric neutrino mass ratio $m_\odot/m_{\rm atm}\simeq \theta_{\rm Cabibbo}$ in agreement with observations. The model predicts the neutrino mixing parameter, $U_{e3} \simeq \theta_{\rm Cabibbo}/(3\sqrt2) \sim 0.05$, which should be observable in planned long baseline experiments.Comment: Final version of the paper as it will appear in JHEP

Neutrino Masses in the Supersymmetric Standard Model with Right-Handed Neutrinos and Spontaneous R-Parity Violation

We propose an extension of the supersymmetric standard model with right-handed neutrinos and a singlet Higgs field, and study the neutrino masses in this model. The Majorana masses for the right-handed neutrinos are generated around the supersymmetry breaking scale through the vacuum expectation value of the singlet Higgs field. This model may induce spontaneous R-parity violation via the vacuum expectation value of the right-handed sneutrino. In the case, the effective theory is similar to a bilinear R-parity violating model. There are two sources for the neutrino masses: one is this bilinear R-parity breaking effect, and the other is the ordinary seesaw effect between left- and right-handed neutrinos. Combining these two effects, the hierarchical neutrino mass pattern arises even when the neutrino Yukawa matrices are not hierarchical. We acquire appropriate masses and mixings to explain both the solar and atmospheric neutrino oscillations.Comment: 22pages, RevTeX, 3 ps figures; a reference adde

Neutrino Oscillations in Supersymmetry without Lepton number conservation and R-parity

With the on-shell renormalization scheme, we discuss neutrino masses up to one-loop approximation in the Supersymmetry without lepton number conservation and R-parity. Ii is shown that in this model with experimentally allowed parameters, $\Delta m^2_{23}, \Delta m^2_{12}$ and the mixing angles $|\sin\theta{23}|,|\sin\theta_{12}|$ which are consistent with the present observation values can be produced. We find that small neutrino mass ($\leq$ 1 eV) sets a loose constraint on the R-parity violation parameters in the soft breaking terms.Comment: 22 pages, plus one ps figure, accepted for publication in PR

Constraining an R-parity violating supersymmetric theory from the SuperKamiokande data on atmospheric neutrinos

The constraints on an R-parity violating supersymmetric theory arising from the recent SuperKamiokande results on atmospheric neutrinos are studied, with special reference to a scenario with bilinear R-parity violating terms. Considering both the fermionic and scalar sectors, we find that a large area of the parameter space is allowed, in terms of both the lepton-number violating entries in the superpotential and the soft R-violating terms in the scalar potential, and that no fine-tuning is required. However, the need to avoid flavour changing neutral currents puts additional restrictions on the theory, requiring either the R-violating terms in the superpotential to be smaller than the R-conserving ones, or a hierarchy in the R-violating parameters for different lepton flavours in the superpotential.Comment: 18 pages, LaTex including postscript figure

Repressing Anarchy in Neutrino Mass Textures

The recent results that $\theta_{13}$ is relatively large, of the order of the previous upper bound, and the indications of a sizable deviation of $\theta_{23}$ from the maximal value are in agreement with the predictions of Anarchy in the lepton sector. The quark and charged lepton hierarchies can then be reproduced in a SU(5) GUT context by attributing non-vanishing $U(1)_{FN}$ charges, different for each family, only to the SU(5) tenplet states. The fact that the observed mass hierarchies are stronger for up quarks than for down quarks and charged leptons supports this idea. As discussed in the past, in the flexible context of $SU(5)\otimes U(1)_{FN}$, different patterns of charges can be adopted going from Anarchy to various types of hierarchy. We revisit this approach by also considering new models and we compare all versions to the present data. As a result we confirm that, by relaxing the extreme ansatz of equal $U(1)_{FN}$ charges for all SU(5) pentaplets and singlets, better agreement with the data than for Anarchy is obtained without increasing the model complexity. We also present the distributions obtained in the different models for the Dirac CP-violating phase. Finally we discuss the relative merits of these simple models.Comment: v1: 12 pages, 3 figures; v2: 13 pages, 3 figures, text improved, matches version accepted for publication; v3: submitted to add an acknowledgment to a networ

Broken R-parity, stop decays, and neutrino physics

We discuss the phenomenology of the lightest stop in models where R-parity is broken by bilinear superpotential terms. In this class of models we consider scenarios where the R-parity breaking two-body decay ~t_1->\tau^+b competes with the leading three-body decays such as ~t_1->W^+b~\chi^0_1. We demonstrate that the R-parity violating decay can be sizable and in some parts of the parameter space even the dominant one. Moreover we discuss the expectations for \~t_1->\mu^+b and ~t_1->e^+b. The recent results from solar and atmospheric neutrinos suggest that these are as important as the tau bottom mode. The \~t_1->l^+b decays are of particular interest for hadron colliders, as they may allow a full mass reconstruction of the lighter stop. Moreover these decay modes allow cross checks on the neutrino mixing angle involved in the solar neutrino puzzle complementary to those possible using neutralino decays. For the so--called small mixing angle or SMA solution ~t_1->e^+b should be negligible, while for the large mixing angle type solutions all ~t_1->l^+b decays should have comparable magnitude.Comment: 51 pages, 6 figures, LaTeX2e and RevTeX4, published versio

Fermion Electric Dipole Moments in Supersymmetric Models with R-parity Violation

We analyze the electron and neutron electric dipole moments induced by R-parity violating interactions in supersymmetric models. It is pointed out that dominant contributions can come from one-loop diagrams involving both the bilinear and trilinear R-parity odd couplings, leading to somewhat severe constraints on the products of those couplings.Comment: Revtex, 19pp, four figures in axodraw.st