arXiv subjects
Publications and source records attributed to J. Barranco.
We revisited the scenario of a resonant enhancement in the oscillation probability due to an interaction potential between neutrinos and dark matter with the novelty of the inclusion of the generalized uncertainty principle. It is shown that a new resonant conversion appears at higher energies. This effect could be tested with future neutrino data as new dips in the ultrahigh energy neutrino flux.
In this work, we show that stimulated decay of axions or axion-like particles in black hole superradiance is an efficient way to find and hunt primordial black holes. When de Broglie's wavelength of the axion/ALP is comparable or larger than the black hole horizon radius, a large population of such particles accumulates in the surroundings of the black hole. When these axions/ALPs couple to photons, the bosonic cloud decays into photon pairs, generating intense stimulated radiation emission that contributes to the X-ray, visible light, and radio wave background flux that can exceed current observational limits measured at Earth. If the masses are in the interval of $10^{-3}\mathrm{eV}<\mu <1\mathrm{eV}$, to be consistent with current observations of microwave background light, we found that the fraction of primordial black holes should be smaller than $f_{PBH} < 10^{-17}$ for PBHs with masses within $10^{-13} M_{\odot}<M_{BH}<10^{-7} M_\odot$.
It is well known that the coupling of an axion-like particle with a photon modifies the Maxwell equations. One of the main consequences of these modifications is the conversion of axions into photons. Little has been said about other possible effects. In this paper we show that the trajectory of an electron can be significantly altered because of the emergence of an electric field due to the dark matter background of the axion-like particles in this modified axion-electrodynamics. Different dark matter densities and magnetic field strengths are considered and it is shown that an axion-like particle with a mass $m_a \sim 10^{-22}$ eV generates an electric field that can significantly change the trajectory of an electron in these scenarios.
In this work we compute the resonant wavelength of whispering gallery modes for bulk-fused silica microspheres including chromatic dispersion. This is done following two methods: by solving the exact characteristic equation and, on the other hand, by solving the nonlinear equations that result for a variable refractive index in the asymptotic approximations. Similar results with both methods are obtained with differences below $1\%$ . Nevertheless, important differences are found with respect to the resonant wavelengths computed with a constant index and with a variable index. We compute the free spectral range and the quality factor, and make a comparison between the variable index and the constant index cases. The differences are of significant relevance for the free spectral range, while for the quality factor, the constant case is insensitive to the chromatic dispersion. Our work could be useful as a pathway for designing microspheres for different applications.
Cold Dark Stars made of self-gravitating fermions in the degenerate limit are constructed in General Relativity and in R-square gravity, $f(R)=R+αR^2$. The properties of the resulting Cold Dark Stars in both theories of gravity are studied. It is found that the same gravitational potential is generated for different election of the parameters of the model, such as the mass of the fermion, the self-interacting strength or the value of $α$, thus, a possible confusion in the determination of the dark matter properties and the favored theory of gravity might arise.
Massive neutrinos can have helicity $s_{\parallel}\neq -1$. Neutrino helicity changes when the neutrino interacts with an external magnetic field and it is possible that the left-handed neutrinos born inside the Sun or a supernova could leave their sources with a different helicity. Since Dirac and Majorana neutrinos have different cross sections in the scattering on electrons for different neutrino helicities, a change in the final neutrino helicity may generate a different number of events and spectra in terrestrial detectors when astrophysical neutrinos have travelled regions with strong magnetic fields. In this work, we show that looking for these effects in solar neutrinos, it could be possible to set bounds in the neutrino properties such as the neutrino magnetic moment. Furthermore, for neutrinos coming from a supernova, we show that even in the case of an extremely small neutrino magnetic moment, $μ_ν\sim 10^{-19}μ_B$, there will be measurable differences in both the number of events and in the spectra of Majorana and Dirac neutrinos.
The equation of state for a degenerate gas of fermions at zero temperature in the non-relativistic case is a polytrope, i.e. $p \sim\rho^{5/3}/m_F^{8/3}$. If dark matter is modeled by such a non-interacting fermion, this dependence in the mass of the fermion $m_F$ explains why if dark matter is very heavy the effective pressure of dark matter is negligible. Nevertheless, if the mass of the dark matter is very small, the effective pressure can be very large, and thus a system of self-gravitating fermions can be formed. In this work we model the dark matter halo of the Milky-Way by solving the Tolman-Oppenheimer-Volkoff equations, with the equation of state for a partially degenerate ultralight non-interacting fermion. We found that to fit the rotational velocity curve of the Milky-Way, the mass of the fermion should be in the range $31.5 ~\mbox{eV} < m_F < 35~$eV at $90\%$ C.L. Moreover, the central density is restricted to be in the range of $1.2 < \rho_0<1.7$ GeV/cm$^3$ at $90\%$ C.L. The fermionic dark matter halo has a very different profile as compared with the standard Navarro-Frenk-White profile, thus, the possible indirect signals for annihilating dark matter may change by orders of magnitude. We found bounds for the annihilation cross section in this case by using the Saggitarius A* spectral energy distribution.
The future detection and measurement of the diffuse neutrino supernova background will shed light on the rate of supernovae events in the Universe, the star formation rate and the neutrino spectrum from each supernova. Little has been said about what those measurements will tell us about the expansion history of the universe. The purpose of this article is to show that the detection of the diffuse supernova neutrino background will be a complementary tool for the study and possible discrimination of cosmological models. In particular, we study three different cosmological models: the $Λ$ Cold Dark Matter model, the Logotropic universe and a bulk viscous matter-dominated universe. By fitting the free parameters of each model with the supernova Ia probe, we found that the predicted number of events computed with the best fit parameters for the $Λ$-Cold dark matter model and with the Logotropic model are the same, while a bulk viscous matter-dominated cosmological model predicts $\sim 3$ times more events. We show that the current limit set by Super-Kamiokande on the diffuse supernova neutrino background flux gives complementary constraints on the free parameters of a bulk viscous matter-dominated universe. Furthermore, this limit implies, within a $Λ$ Cold Dark Matter model, that the universe should be expanding with $H_0 > 21.5 ~\rm{Km/sec/Mpc}$ independently of the content of dark matter $Ω_m$.
Chapter 2 in High-Luminosity Large Hadron Collider (HL-LHC) : Preliminary Design Report. The Large Hadron Collider (LHC) is one of the largest scientific instruments ever built. Since opening up a new energy frontier for exploration in 2010, it has gathered a global user community of about 7,000 scientists working in fundamental particle physics and the physics of hadronic matter at extreme temperature and density. To sustain and extend its discovery potential, the LHC will need a major upgrade in the 2020s. This will increase its luminosity (rate of collisions) by a factor of five beyond the original design value and the integrated luminosity (total collisions created) by a factor ten. The LHC is already a highly complex and exquisitely optimised machine so this upgrade must be carefully conceived and will require about ten years to implement. The new configuration, known as High Luminosity LHC (HL-LHC), will rely on a number of key innovations that push accelerator technology beyond its present limits. Among these are cutting-edge 11-12 tesla superconducting magnets, compact superconducting cavities for beam rotation with ultra-precise phase control, new technology and physical processes for beam collimation and 300 metre-long high-power superconducting links with negligible energy dissipation. The present document describes the technologies and components that will be used to realise the project and is intended to serve as the basis for the detailed engineering design of HL-LHC.
It is well known that Majorana neutrinos have a pure axial neutral current interaction while Dirac neutrinos have the standard vector-axial interaction. In spite of this crucial difference, usually Dirac neutrino processes differ from Majorana processes by a term proportional to the neutrino mass, resulting in almost unmeasurable observations of this difference. In the present work we show that once the neutrino polarization evolution is considered, there are clear differences between Dirac and Majorana scattering on electrons. The change of polarization can be achieved in astrophysical environments with strong magnetic fields. Furthermore, we show that in the case of unpolarized neutrino scattering onto polarized electrons, this difference can be relevant even for large values of the neutrino energy.
We use a combined analysis of the semileptonic and leptonic branching ratios of the D mesons to constrain scalar leptoquark interactions and charged higgs-like interactions. For the THDM type II, we found that a low mass 6.3GeV < m_{H^+} < 63.1GeV for the charged Higgs is favored at 90% C.L. although at 95% there is still agreement with other constraints. We find for the leptoquark states a more restrictive bound than previous analysis.
Latest Lattice results on $D$ form factors evaluation from first principles show that the standard model (SM) branching ratios prediction for the leptonic $D_s \to \ell ν_\ell$ decays and the semileptonic SM branching ratios of the $D^0$ and $D^+$ meson decays are in good agreement with the world average experimental measurements. It is possible to disprove New Physics hypothesis or find bounds over several models beyond the SM. Using the observed leptonic and semileptonic branching ratios for the D meson decays, we performed a combined analysis to constrain non standard interactions which mediate the $c\bar{s}\to l\barν$ transition. This is done either by a model independent way through the corresponding Wilson coefficients or in a model dependent way by finding the respective bounds over the relevant parameters for some models beyond the standard model. In particular, we obtain bounds for the Two Higgs Doublet Model Type-II and Type III, the Left-Right model, the Minimal Supersymmetric Standard Model with explicit R-Parity violation and Leptoquarks. Finally, we estimate the transverse polarization of the lepton in the $D^0$ decay and we found it can be as high as $P_T=0.23$.
If dark matter is mainly composed of axions, the density distribution can be nonuniformly distributed, being clumpy instead. By solving the Einstein-Klein-Gordon system of a scalar field with the potential energy density of an axionlike particle, we obtain the maximum mass of the self-gravitating system made of axions, called axion stars. The collision of axion stars with neutron stars may release the energy of axions due to the conversion of axions into photons in the presence of the neutron star's magnetic field. We estimate the energy release and show that it should be much less than previous estimates.Future data from femtolensing should strongly constrain this scenario.
Motivated by the stringent flux limits for UHE neutrinos coming from gamma ray burst or active galactic nuclei, we explore the possibility that the active neutrinos generated in such astrophysical objects could oscillate to sterile right handed states due to a neutrino magnetic moment mu_nu. We find that a value as small as mu_nu ~1E-15 mu_B could produce such a transition thanks to the intense magnetic fields that are expected in these objects.
We analyze the different parametrizations of a general four-zero texture mass matrices for quarks and leptons, that are able to reproduce the CKM and PMNS mixing matrices. This study is done through a Chi-Square analysis. In quark sector, only four solutions are found to be compatible with CKM mixing matrix. In leptonic sector, using the last experimental results about the mixing angles in the neutrino sector, our Chi-Square analysis shows a preferred value for m_nu_3 to be around 0.05 eV independently of the parametrization of the four-zero texture mass matrices chosen for the charged leptons and neutrinos.
We have analyzed the electron anti-neutrino scattering off electrons and the electron anti-neutrino-nuclei coherent scattering in order to obtain constraints on tensorial couplings. We have studied the formalism of non-standard interactions (NSI), as well as the case of Unparticle physics. For our analysis we have focused on the recent TEXONO collaboration results and we have obtained current constraints to possible electron anti-neutrino-electron tensorial couplings in both new physics formalisms. The possibility of measuring for the first time electron anti-neutrino-nucleus coherent scattering and its potential to further constrain electron anti-neutrino-quark tensorial couplings is also discussed.
The emittance preservation in the Beam Delivery System (BDS) is one of the major challenges in CLIC. The fast detuning of the final focus optics requires an on-line tuning procedure in order to keep luminosity close to the maximum. Different tuning techniques have been applied to the CLIC BDS and in particular to the Final Focus System (FFS) in order to mitigate static and dynamic imperfections. Some of them require a fast luminosity measurement. Here we study the possibility to use beam-beam backgrounds processes at CLIC 3 TeV CM energy as fast luminosity signal. In particular the hadrons multiplicity in the detector region is investigated.
We study the possible suppression of the extragalactic neutrino flux due to a nonstandard interaction during its propagation. In particular, we study neutrino interaction with an ultra-light scalar field dark matter. It is shown that the extragalactic neutrino flux may be suppressed by such an interaction, leading to a new mechanism to reduce the ultra-high energy neutrino flux. We study both the cases of non-self-conjugate as well as self-conjugate dark matter. In the first case, the suppression is independent of the neutrino and dark matter masses. We conclude that care must be taken when explaining limits on the neutrino flux through source acceleration mechanisms only, since there could be other mechanisms for the reduction of the neutrino flux.