arXiv subjects

O. Vives

Publications and source records attributed to O. Vives.

At least 37 records · Page 2Linked to original sources

arXiv2011

SUSY Flavour at LHC7

The current 7 TeV run of the LHC experiment shall be able to probe gluino and squark masses up to values of about 1 TeV. Assuming that hints for SUSY are found by the end of a 2 fb$^{-1}$ run, we explore the flavour constraints on the parameter space of the CMSSM, with and without massive neutrinos. In particular, we focus on decays that might have been measured by the time the run is concluded, such as $B_s\toμμ$ and $μ\to eγ$. We also briefly show the impact such a collider--flavour interplay would have on a Flavoured CMSSM.

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arXiv2009

FCNC and CP Violation Observables in a SU(3)-flavoured MSSM

A non-Abelian flavour symmetry in a minimal supersymmetric standard model can explain the flavour structures in the Yukawa couplings and simultaneously solve the SUSY flavour problem. Similarly the SUSY CP problem can be solved if CP is spontaneously broken in the flavour sector. In this work, we present an explicit example of these statements with a SU(3) flavour symmetry and spontaneous CP violation. In addition, we show that it is still possible to find some significant deviation from the SM expectations as far as FCNC and CP violation are concerned. We find that large contributions can be expected in lepton flavour violating decays, as $μ\to e γ$ and $τ\to μγ$, electric dipole moments, $d_e$ and $d_n$ and kaon CP violating processes as $ε_K$. Thus, these flavoured MSSM realizations are phenomenologically sensitive to the experimental searches in the realm of flavor and CP vioation physics.

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arXiv2009

SU(3) Flavour Symmetries and CP Violation

In order to satisfy current FCNC and CP violation bounds, SUSY flavour structures cannot be generic. An interesting solution to these SUSY Flavour and CP Problems lies on the use of an SU(3) family symmetry which spontaneously breaks CP symmetry. Typical observables of such a model are electric dipole moments and LFV processes. In addition, these models can give contributions to CP violation in neutral meson mixing. We show how the latter can be used to restrict the allowed SUSY parameter space, and induce correlations between LFV and EDM predictions.

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arXiv2009

On the full Boltzmann equations for Leptogenesis

We consider the full Boltzmann equations for standard and soft leptogenesis, instead of the usual integrated Boltzmann equations which assume kinetic equilibrium for all species. Decays and inverse decays may be inefficient for thermalising the heavy-(s)neutrino distribution function, leading to significant deviations from kinetic equilibrium. We analyse the impact of using the full kinetic equations in the case of a previously generated lepton asymmetry, and find that the washout of this initial asymmetry due to the interactions of the right-handed neutrino is larger than when calculated via the integrated equations. We also solve the full Boltzmann equations for soft leptogenesis, where the lepton asymmetry induced by the soft SUSY-breaking terms in sneutrino decays is a purely thermal effect, since at T=0 the asymmetry in leptons cancels the one in sleptons. In this case, we obtain that in the weak washout regime (K ~< 1) the final lepton asymmetry can change up to a factor four with respect to previous estimates.

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arXiv2009

Long-Lived Slepton in the Coannihilation Region and Measurement of Lepton Flavour Violation at LHC

When the mass difference between the lightest slepton and the lightest neutralino is smaller than the tau mass, the lifetime of the lightest slepton in the constrained Minimal Supersymmetric Standard Model (MSSM) increases in many orders of magnitude with respect to typical lifetimes of other supersymmetric particles. In a general MSSM, the lifetime of the lightest slepton is inversely proportional to the square of the intergenerational mixing in the slepton mass matrices. Such a long-lived slepton would produce a distinctive signature at LHC and a measurement of its lifetime would be relatively simple. Therefore, the long-lived slepton scenario offers an excellent opportunity to study lepton flavour violation at ATLAS and CMS detectors in the LHC and an improvement of the leptonic mass insertion bounds by more than five orders of magnitude would be possible.

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arXiv2008

About a (standard model) universe dominated by the right matter

We analyze the phenomenology of a prolonged early epoch of matter domination by an unstable but very long-lived massive particle. This new matter domination era can help to relax some of the requirements on the primordial inflation. Its main effect is the huge entropy production produced by the decays of such particle that can dilute any possible unwanted relic, as the gravitino in supersymmetric models, and thus relax the constraints on the inflationary reheating temperature. Furthermore, a long period of matter domination reduces the number of $e$-foldings after the horizon crossing by observable perturbations and therefore the requirements on flatness of the inflationary potential. A natural candidate for such heavy, long-lived particle already present in the Standard Model of the electroweak interactions would be a heavy right-handed neutrino. In this case, we show that its decays can also generate the observed baryon asymmetry with right-handed neutrino masses well above the bound from gravitino overproduction.

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arXiv2008

Proceedings of SuperB Workshop VI: New Physics at the Super Flavor Factory

The sixth SuperB Workshop was convened in response to questions posed by the INFN Review Committee, evaluating the SuperB project at the request of INFN. The working groups addressed the capability of a high-luminosity flavor factory that can gather a data sample of 50 to 75 /ab in five years to elucidate New Physics phenomena unearthed at the LHC. This report summarizes the results of the Workshop.

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arXiv2008

Electric dipole moments from flavoured CP violation in SUSY

The so-called supersymmetric flavour and CP problems are deeply related to the origin of flavour and hence to the origin of the SM Yukawa couplings themselves. We show that realistic SU(3) flavour symmetries with spontaneous CP violation reproducing correctly the SM Yukawa matrices can simultaneously solve both problems without ad hoc modifications of the SUSY model. We analyze the leptonic electric dipole moments and lepton flavour violation processes in these models. We show that the electron EDM and the decay mu -> e gamma are naturally within reach of the proposed experiments if the sfermion masses are measurable at the LHC.

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arXiv2008

Flavour physics of leptons and dipole moments

This chapter of the report of the ``Flavour in the era of the LHC'' Workshop discusses the theoretical, phenomenological and experimental issues related to flavour phenomena in the charged lepton sector and in flavour-conserving CP-violating processes. We review the current experimental limits and the main theoretical models for the flavour structure of fundamental particles. We analyze the phenomenological consequences of the available data, setting constraints on explicit models beyond the Standard Model, presenting benchmarks for the discovery potential of forthcoming measurements both at the LHC and at low energy, and exploring options for possible future experiments.

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arXiv2007

Flavour Physics and Grand Unification

In spite of the enormous success of the Standard Model (SM), we have strong reasons to expect the presence of new physics beyond the SM at higher energies. The idea of the Grand Unification of all the known interactions in nature is perhaps the main reason behind these expectations. Low-energy Supersymmetry is closely linked with grand unification as a solution of the hierarchy problem associated with the ratio M_GUT / M_Z. In these lectures we will provide a general overview of Grand Unification and Supersymmetry with special emphasis on their phenomenological consequences at low energies. We will analyse the flavour and CP problems of Supersymmetry and try to identify in these associated low-energy observables possible indications of the existence of a Grand Unified theory at high energies.

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arXiv2007

Soft SUSY Breaking Grand Unification: Leptons vs Quarks on the Flavor Playground

We systematically analyze the correlations between the various leptonic and hadronic flavor violating processes arising in SUSY Grand Unified Theories. Using the GUT-symmetric relations between the soft SUSY breaking parameters, we assess the impact of hadronic and leptonic flavor observables on the SUSY sources of flavor violation.

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arXiv2006

Invariant approach to flavour-dependent CP-violating phases in the MSSM

We use a new weak basis invariant approach to classify all the observable phases in any extension of the Standard Model (SM). We apply this formalism to determine the invariant CP phases in a simplified version of the Minimal Supersymmetric SM with only three non-trivial flavour structures. We propose four experimental measures to fix completely all the observable phases in the model. After these phases have been determined from experiment, we are able to make predictions on any other CP-violating observable in the theory, much in the same way as in the Standard Model all CP-violation observables are proportional to the Jarlskog invariant.

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arXiv2006

Flavoured leptogenesis: a successful thermal leptogenesis with N_1 mass below 10^8 GeV

We prove that taking correctly into account the lepton flavour dependence of the CP asymmetries and washout processes, it is possible to obtain successful thermal leptogenesis from the decays of the second right-handed neutrino. The asymmetries in the muon and tau-flavour channels are then not erased by the inverse decays of the lightest right-handed neutrino, N_1. In this way, we reopen the possibility of ``thermal leptogenesis'' in models with a strong hierarchy in the right-handed Majorana masses that is typically the case in models with up-quark--neutrino Yukawa unification.

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arXiv2005

The Discovery Potential of a Super B Factory

The Proceedings of the 2003 SLAC Workshops on flavor physics with a high luminosity asymmetric e+e- collider. The sensitivity of flavor physics to physics beyond the Standard Model is addressed in detail, in the context of the improvement of experimental measurements and theoretical calculations.

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arXiv2004

SUSY Seesaw and FCNC

After a quarter of century of intense search for new physics beyond the Standard Model (SM), two ideas stand out to naturally cope with (i) small neutrino masses and (ii) a light higgs boson : Seesaw and SUSY. The combination of these two ideas, i.e. SUSY seesaw exhibits a potentially striking signature: a strong (or even very strong) enhancement of lepton flavour violation (LFV), which on the contrary remains unobservable in the SM seesaw. Indeed, even when supersymmetry breaking is completely flavour blind, Renormalisation Group running effects are expected to generate large lepton flavour violating entries at the weak scale. In Grand Unified theories, these effects can be felt even in hadronic physics. We explicitly show that in a class of SUSY SO(10) GUTs there exist cases where LFV and CP violation in B-physics can constitute a major road in simultaneously confirming the ideas of Seesaw and low-energy SUSY.

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arXiv2003

Grand Unification of Quark and Lepton FCNCs

In the context of Supersymmetric Grand Unified theories with soft breaking terms arising at the Planck scale, it is generally possible to link flavor changing neutral current and CP violating processes occurring in the leptonic and hadronic sectors. We study the correlation between flavor changing squark and slepton mass insertions in models à la SU(5). We show that the constraints coming from lepton flavor violation exhibit a strong impact on CP-violating B decays.

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arXiv2003

Yukawa structure, flavour and CP violation in Supergravity

The hierarchical structure of fermion masses and mixings strongly suggests an underlying family symmetry. In supergravity any familon field spontaneously breaking this symmetry necessarily acquires an F-term which contributes to the soft trilinear couplings. We show, as a result, mu -> e gamma decay can receive large contributions from this source at the level of current experimental bounds and thus this channel may provide the first indication of supersymmetry and a clue to the structure of the soft breaking sector. Using the mercury EDM bounds we find strong bounds on the right handed down quark mixing angles that are inconsistent with models relating them to neutrino mixing angles and favour a near-symmetric form for the magnitude of the down quark mass matrix.

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arXiv2001

General Flavour Blind MSSM and CP Violation

We study FCNC and CP violating processes in the MSSM without a new flavour structure (flavour blind MSSM). The low energy parameters are determined by the running of the soft breaking terms from the GUT scale with SUSY phases consistent with the EDM constraints. We find that the CP asymmetry in b -> s gamma can reach large values potentially measurable at B factories, especially in the low BR(b -> s gamma) region. We analyze the SUSY contributions to the anomalous magnetic moment of the muon pointing out its impact on the b -> s gamma CP asymmetry and on the SUSY spectrum.

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