Eviction of a 125 GeV "heavy"-Higgs from the MSSM

We prove that the present experimental constraints are already enough to rule out the possibility of the ~125 GeV Higgs found at LHC being the second lightest Higgs in a general MSSM context, even with explicit CP violation in the Higgs potential. Contrary to previous studies, we are able to eliminate this possibility analytically, using simple expressions for a relatively small number of observables. We show that the present LHC constraints on the diphoton signal strength, tau-tau production through Higgs and BR(B -> X_s gamma) are enough to preclude the possibility of H_2 being the observed Higgs with m_H~125 GeV within an MSSM context, without leaving room for finely tuned cancellations. As a by-product, we also comment on the difficulties of an MSSM interpretation of the excess in the gamma-gamma production cross section recently found at CMS that could correspond to a second Higgs resonance at m_H~136 GeV.Comment: 38 pages, 9 figures. Final version accepted at JHEP. Sections 2, 3 and appendices simplified. Experimental results updated, several references added. Small typos corrected and a new comparison of approximate formulas with full expressions include

Zero-point quantum swing of magnetic couples

Quantum fluctuations are ubiquitous in physics. Ranging from conventional examples like the harmonic oscillator to intricate theories on the origin of the universe, they alter virtually all aspects of matter -- including superconductivity, phase transitions and nanoscale processes. As a rule of thumb, the smaller the object, the larger their impact. This poses a serious challenge to modern nanotechnology, which aims total control via atom-by-atom engineered devices. In magnetic nanostructures, high stability of the magnetic signal is crucial when targeting realistic applications in information technology, e.g. miniaturized bits. Here, we demonstrate that zero-point spin-fluctuations are paramount in determining the fundamental magnetic exchange interactions that dictate the nature and stability of the magnetic state. Hinging on the fluctuation-dissipation theorem, we establish that quantum fluctuations correctly account for the large overestimation of the interactions as obtained from conventional static first-principles frameworks, filling in a crucial gap between theory and experiment [1,2]. Our analysis further reveals that zero-point spin-fluctuations tend to promote the non-collinearity and stability of chiral magnetic textures such as skyrmions -- a counter-intuitive quantum effect that inspires practical guidelines for designing disruptive nanodevices

Origin of non-keplerian motions of masers in NGC 1068

We demonstrate that the ``sub-keplerian'' rotation curve of maser spots in NGC 1068 can be explained by the gravitational attraction of the disc orbiting the central black hole. Possible parameters matching observations are: black hole mass of 12 million solar masses, disc outer edge > 1.3 pc, aspect ratio in the range 0.003 to 0.3, surface density varying approximately as 1/R, and disc mass of about 9.4 million solar masses. The physical conditions required for the excitation of masers are fulfilled, and the outer disc would stand in a gravitationally marginally stable state.Comment: 4 pages; accepted in A&A Letter

Ross 128-GL 447: A possible activity cycle for a slow-rotating fully convective star

Context. Long-term chromospheric activity in slow-rotating fully convective stars has scarcely been explored. Ross 128 (Gl 447) is a slow-rotator and inactive dM4 star that has been extensively observed. It hosts the fourth closest extrasolar planet. Aims. Ross 128 is an ideal target to test dynamo theories in slow-rotating low-mass stars. Methods. To characterize the magnetic activity of Ross 128, we studied the SK-indexes derived from CASLEO, HARPS, FEROS, UVES, and X-shooter spectra. Using the generalized Lomb-Scargle and CLEAN periodograms, we analyzed the whole SK time-series obtained between 2004 and 2018. We performed a similar analysis for the Na I-index, and we analyzed its relation with the SK-index. Results. From both indexes, we obtain a possible activity cycle with a period of about five years, which is one of a small handful of activity cycles that have been reported for a slow-rotating fully convective star.Fil: Ibañez Bustos, Romina Valeria. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Buccino, Andrea Paola. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Flores, M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: Mauas, Pablo Jacobo David. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentin

Tuning paramagnetic spin-excitations of single adatoms

Around 50 years ago, Doniach [Proc. Phys. Soc. 91, 86 (1967)] predicted the existence of paramagnons in nearly ferromagnetic materials, recently measured in bulk Pd [Phys. Rev. Lett. 105, 027207 (2010)]. Here we predict the analogous effect for single adatoms, namely paramagnetic spin-excitations (PSE). Based on time-dependent density functional theory, we demonstrate that these overdamped excitations acquire a well-defined peak structure in the meV energy region when the adatom's Stoner criterion for magnetism is close to the critical point. In addition, our calculations reveal a subtle tunability and enhancement of PSE by external magnetic fields, exceeding by far the response of bulk paramagnons and even featuring the atomic version of a quantum phase transition. We further demonstrate how PSE can be detected as moving steps in the $\mathrm{d}I/dV$ signal of state-of-the-art inelastic scanning tunneling spectroscopy, opening a potential route for experimentally accessing fundamental electronic properties of non-magnetic adatoms, such as the Stoner parameter.Comment: 6 pages, 3 figure

Colonización espontánea de taludes de desmonte sobre margas en Navarra: establecimiento y fuente de diásporas.

Tras la hidrosiembra de taludes de desmonte sobre margas en localidades navarras con clima submediterráneo se implanta una cubierta vegetal de especies hidrosembradas que experimenta una rápida regresión, tal y como hemos observado en estudios previos. A pesar de ello, algunas especies autóctonas son capaces de colonizar estas superficies. Describimos la capacidad de colonización de estas últimas especies, cuyas diásporas proceden de la lluvia de semillas, para determinar si también les afecta la regresión observada en las especies hidrosembradas. También estudiamos su distribución espacial para determinar la fuente de diásporas. A pesar de la gran dificultad para colonizar los desmontes, las especies autóctonas no siguen el modelo regresivo que presentan las especies hidrosembradas en desmontes de similares características en Navarra. Por otro lado, la mayoría de las especies disminuyen su abundancia al aumentar la distancia a la zona superior del talud, donde se encuentra la vegetación que actúa como principal fuente de diásporas

Radiative Electroweak Symmetry Breaking and the Infrared Fixed Point of the Top Quark Mass

The infrared quasi fixed point solution for the top quark mass in the Minimal Supersymmetric Standard Model explains in a natural way large values of the top quark mass and appears as a prediction in many interesting theoretical schemes. Moreover, as has been recently pointed out, for moderate values of $\tan\beta$, in order to achieve gauge and bottom-tau Yukawa coupling unification, the top quark mass must be within $10 \%$ of its fixed point value. In this work we show that the convergence of the top quark mass to its fixed point value has relevant consequences for the (assumed) universal soft supersymmetry breaking parameters at the grand unification scale. In particular, we show that the low energy parameters do not depend on $A_0$ and $B_0$ but on the combination $\delta = B_0 - A_0/2$. Hence, there is a reduction in the number of independent parameters. Most interesting, the radiative $SU(2)_L \times U(1)_Y$ breaking condition implies strong correlations between the supersymmetric mass parameter $\mu$ and the supersymmetry breaking parameters $\delta$ and $M_{1/2}$ or $m_0$. These correlations, which become stronger for $\tan\beta < 2$, may have some fundamental origin, which would imply the need of a reformulation of the naive fine tuning criteria.Comment: 17 pages, 5 figures, CERN-TH.7060/9

Avaliação de desempenho lumínico: imagens HDR

Anais do VI Encontro de Iniciação Científica e II Encontro Anual de Iniciação ao Desenvolvimento Tecnológico e Inovação – EICTI 2017 - 04 a 06 de outubro de 2017 - temática EngenhariaCom o passar do tempo e a diminuição do espaço livre, construções existentes são adaptadas para desenvolver atividades diferentes das quais foram construídas, assim, é comum observar ambientes com pouca iluminação para desenvolver as atividades necessárias nos ambientes de trabalho, poiso ideal é que as decisões referentes à iluminação natural sejam tomadas ainda na fase inicial do projeto. Estudos de luminância analisam a qualidade de iluminação num ambiente construído, e frequentemente estão acompanhados de novas ferramentas, como é o caso do uso de fotografias, que permitem realizar o estudo de maneira rápida e econômica em relação à maneira tradicional. Portanto, as imagens HDR compostas a partir de imagens digitais podem ser utilizadas, com algumas restrições de precisão, como ferramenta para levantamento da distribuição das luminâncias num ambiente (IBAÑEZ; ZAFRA; SACHT, 2017) Com base em tais informações, o presente trabalho teve como objetivo gerar imagens de grande alcance dinâmico ou High Dynamic Range (HDR) de um ambiente, para estudo da qualidade de iluminação e comparação com dados de medição in locoUniversidade Federal da Integração Latino-Americana (Unila); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação Araucária; Parque Tecnológico Itaipu (PTI) e Companhia de Saneamento do Paraná (SANEPAR