Search for Heavy Stable Charged Particles at CMS

Some supersymmetric and/or extra dimensions models predict the existence of “Heavy Stable Charged Particles” (HSCP) which could be produced at LHC. In pp collisions at √s = 7TeV, the observation of tracks with β = v/c < 1 would constitute a distinctive sign of HSCP production. At CMS, β can be measured in the tracker, from the specific ionization dE/dx, and/or in the muon system, by evaluating the time of flight (TOF). With the first 3.1 pb−1 at 7TeV, limits have been posed on the mass of some types of HSCP, using only the specific ionization. The CMS search for HSCP production with the 2010 data sample will be presented

Baxter Operators and Hamiltonians for "nearly all" Integrable Closed gl(n) Spin Chains

We continue our systematic construction of Baxter Q-operators for spin chains, which is based on certain degenerate solutions of the Yang-Baxter equation. Here we generalize our approach from the fundamental representation of gl(n) to generic finite-dimensional representations in quantum space. The results equally apply to non-compact representations of highest or lowest weight type. We furthermore fill an apparent gap in the literature, and provide the nearest-neighbor Hamiltonians of the spin chains in question for all cases where the gl(n) representations are described by rectangular Young diagrams, as well as for their infinite-dimensional generalizations. They take the form of digamma functions depending on operator-valued shifted weights

Oscillator construction of su(n|m) Q-operators

We generalize our recent explicit construction of the full hierarchy of Baxter Q-operators of compact spin chains with su(n) symmetry to the supersymmetric case su(n|m). The method is based on novel degenerate solutions of the graded Yang-Baxter equation, leading to an amalgam of bosonic and fermionic oscillator algebras. Our approach is fully algebraic, and leads to the exact solution of the associated compact spin chains while avoiding Bethe ansatz techniques. It furthermore elucidates the algebraic and combinatorial structures underlying the system of nested Bethe equations. Finally, our construction naturally reproduces the representation, due to Z. Tsuboi, of the hierarchy of Baxter Q-operators in terms of hypercubic Hasse diagrams. © 2011 Elsevier B.V

Bootstrapping N= 3 superconformal theories

We initiate the bootstrap program for N= 3 superconformal field theories (SCFTs) in four dimensions. The problem is considered from two fronts: the protected subsector described by a 2d chiral algebra, and crossing symmetry for half-BPS operators whose superconformal primaries parametrize the Coulomb branch of N= 3 theories. With the goal of describing a protected subsector of a family of N= 3 SCFTs, we propose a new 2d chiral algebra with super Virasoro symmetry that depends on an arbitrary parameter, identified with the central charge of the theory. Turning to the crossing equations, we work out the superconformal block expansion and apply standard numerical bootstrap techniques in order to constrain the CFT data. We obtain bounds valid for any theory but also, thanks to input from the chiral algebra results, we are able to exclude solutions with N= 4 supersymmetry,allowingustozoominonaspecific N= 3 SCFT

Qualidade das uvas Niágara Rosada e Isabel em diferentes ambientes no Espírito Santo

Objetivou-se com o presente estudo avaliar o comportamento vitícola das variedades de uva Niágara Rosada e Isabel (Vitis labrusca L.) em três diferentes altitudes no município de Santa Teresa-ES. Um diagnóstico nutricional das plantas dos parreirais foi realizado e a interpretação do estado nutricional foi feita com base no Sistema Integrado de Diagnose e Recomendação (DRIS). Na etapa de avaliação da qualidade das uvas Niágara Rosada e Isabel, realizada em laboratório, foi adotado um delineamento em blocos casualizados em esquema de parcelas subdivididas no espaço, sendo altitudes (parcelas) e as cultivares (subparcelas). Cada um dos tratamentos contou com 5 repetições. Em laboratório, nas bagas, foram determinados os seguintes atributos: teores de sólidos solúveis totais (SST), pH, acidez total titulável (ATT), relação entre SST/ATT e polifenóis totais. O monitoramento do teor de sólidos solúveis totais (SST) durante a maturação das videiras foi realizada semanalmente com auxílio de um refratômetro digital. Cada um dos tratamentos (três altitude e duas cultivares) contou com 10 repetições. Por fim, foi avaliada a variabilidade espacial do teor de sólidos solúveis totais (SST) em um parreiral de uva Isabel na altitude de 650m. Para esta análise construiu-se uma malha amostral regular, em coordenadas locais, totalizando 80 pontos amostrais. A amostragem dos sólidos solúveis totais (SST) das bagas foi realizada com auxílio de um refratômetro digital portátil ATAGO, determinado na parte superior, média e baixa das bagas. Os valores médios por pontos amostral de SST foram submetidos à análise geoestatística a fim de verificar a existência de dependência espacial por meio de ajuste de semivariograma. De um modo geral, observa-se que os níveis de macro e micronutrientes encontrados nos tecidos foliares das cultivares Niágara Rosada e Isabel encontram-se na faixa do ótimo e de ligeiro excesso. Já o DRIS demonstrou que os parreirais apresentavam, em geral, deficiência de zinco, enxofre e cobre e excesso de magnésio, boro, cálcio e ferro. A temperatura mais amena no ambiente 3 (650 m de altitude) contribuiu para menores valores STT e pH e maiores valores de acidez. No ambiente 1 (250 m de altitude), o excesso de nitrogênio contribui para os menores valores de STT e o pH para maiores valores de acidez. A temperatura mais elevada no ambiente 2 (500 m de altitude) contribui para o ganho de STT nas duas cultivares estudadas. O teor de sólidos solúveis apresenta dependência espacial com ajuste do semivariograma ao modelo esférico e gaussiano. A maior concentração de ºBrix encontra-se na parte mais baixa da área, enquanto os menores valores encontram-se na parte mais alta da área

A shortcut to the Q-operator

Baxter's Q-operator is generally believed to be the most powerful tool for the exact diagonalization of integrable models. Curiously, it has hitherto not yet been properly constructed in the simplest such system, the compact spin-1/2 Heisenberg-Bethe XXX spin chain. Here we attempt to fill this gap and show how two linearly independent operatorial solutions to Baxter's TQ equation may be constructed as commuting transfer matrices if a twist field is present. The latter are obtained by tracing over infinitely many oscillator states living in the auxiliary channel of an associated monodromy matrix. We furthermore compare our approach to and differentiate it from earlier articles addressing the problem of the construction of the Q-operator for the XXX chain. Finally we speculate on the importance of Q-operators for the physical interpretation of recent proposals for the Y-system of AdS/CFT. © 2010 IOP Publishing Ltd and SISSA

Spectral parameters for scattering amplitudes in N=4 super Yang-Mills theory

Planar N= 4 Super Yang-Mills theory appears to be a quantum integrable four-dimensional conformal theory. This has been used to find equations believed to describe its exact spectrum of anomalous dimensions. Integrability seemingly also extends to the planar space-time scattering amplitudes of the N= 4 model, which show strong signs of Yangian invariance. However, in contradistinction to the spectral problem, this has not yet led to equations determining the exact amplitudes. We propose that the missing element is the spectral parameter, ubiquitous in integrable models. We show that it may indeed be included into recent on-shell approaches to scattering amplitude integrands, providing a natural deformation of the latter. Under some constraints, Yangian symmetry is preserved. Finally we speculate that the spectral parameter might also be the regulator of choice for controlling the infrared divergences appearing when integrating the integrands in exactly four dimensions. © 2014 The Author(s)

Harmonic R matrices for scattering amplitudes and spectral regularization

Planar N=4 supersymmetric Yang-Mills theory appears to be integrable. While this allows one to find this theory's exact spectrum, integrability has hitherto been of no direct use for scattering amplitudes. To remedy this, we deform all scattering amplitudes by a spectral parameter. The deformed tree-level four-point function turns out to be essentially the one-loop R matrix of the integrable N=4 spin chain satisfying the Yang-Baxter equation. Deformed on-shell three-point functions yield novel three-leg R matrices satisfying bootstrap equations. Finally, we supply initial evidence that the spectral parameter might find its use as a novel symmetry-respecting regulator replacing dimensional regularization. Its physical meaning is a local deformation of particle helicity, a fact which might be useful for a much larger class of nonintegrable four-dimensional field theories. © 2013 American Physical Society

Baxter q-operators and representations of yangians

We develop a new approach to Baxter Q-operators by relating them to the theory of Yangians, which are the simplest examples for quantum groups. Here we open up a new chapter in this theory and study certain degenerate solutions of the Yang-Baxter equation connected with harmonic oscillator algebras. These infinite-state solutions of the Yang-Baxter equation serve as elementary, "partonic" building blocks for other solutions via the standard fusion procedure. As a first example of the method we consider gl(n) compact spin chains and derive the full hierarchy of operatorial functional equations for all related commuting transfer matrices and Q-operators. This leads to a systematic and transparent solution of these chains, where the nested Bethe equations are derived in an entirely algebraic fashion, without any reference to the traditional Bethe Ansatz techniques. © 2011

Outcome at 2-year of treatment in first-episode psychosis patients who were enrolled in a specialized early intervention program

Treatment in early intervention services (EIS) seems superior to treatment as usual on several outcomes, but the extent of heterogeneity in response is unclear. In this study, treatment response trajectories up to 2 years in first-episode psychosis (FEP) patients enrolled in an Italian early intervention service (EIS) have been quantified. The 24-item Brief Psychiatric Rating Scale (BPRS) was used to quantify treatment response up to 2 years in 129 participants. Conditional growth modeling and latent class growth analysis were used to test changes over time in the BPRS and separation into independent classes over time. Group differences were tested on socio-demographic and clinical variables known to be related to outcome in psychosis. Scores on the BPRS showed a statistically significant decrease in overall scores across all tested models. Four trajectories were identified across 2 years. Most patients showed a progressive decrease in the BPRS scores; a scant fraction showed a more stepped decrease from very high levels of psychopathology. No potential predictor was statistically related to the time course of BPRS scores. Most patients that undergo treatment within an EIS are characterized by amelioration, but patients that have higher baseline scores of psychopathology require more intensive treatment