1,397 research outputs found

    Jets in Effective Theory: Summing Phase Space Logs

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    We demonstrate how to resum phase space logarithms in the Sterman-Weinberg (SW) dijet decay rate within the context of Soft Collinear Effective theory (SCET). An operator basis corresponding to two and three jet events is defined in SCET and renormalized. We obtain the RGE of the two and three jet operators and run the operators from the scale μ2=Q2\mu^2 = Q^2 to the phase space scale μδ2=δ2Q2 \mu^2_\delta = \delta^2 Q^2. This phase space scale, where δ\delta is the cone half angle of the jet, defines the angular region of the jet. At μδ2 \mu^2_{\delta} we determine the mixing of the three and two jet operators. We combine these results with the running of the two jet shape function, which we run down to an energy cut scale μβ2\mu^2_{\beta}. This defines the resumed SW dijet decay rate in the context of SCET. The approach outlined here demonstrates how to establish a jet definition in the context of SCET. This allows a program of systematically improving the theoretical precision of jet phenomenology to be carried out.Comment: 25 pages, 4 figures, V2: Typos fixed, writing clarified, detail on PSRG added. Matching onto jet definition changed to taking place at collinear scal

    Application of the Frobenius method to the Schrodinger equation for a spherically symmetric potential: anharmonic oscillator

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    The power series method has been adapted to compute the spectrum of the Schrodinger equation for central potential of the form V(r)=d2r2+d1r+i=0diriV(r)={d_{-2}\over r^2}+{d_{-1}\over r}+\sum_{i=0}^{\infty} d_{i}r^i. The bound-state energies are given as zeros of a calculable function, if the potential is confined in a spherical box. For an unconfined potential the interval bounding the energy eigenvalues can be determined in a similar way with an arbitrarily chosen precision. The very accurate results for various spherically symmetric anharmonic potentials are presented.Comment: 16 pages, 5 figures, published in J. Phys

    Nanosecond Optical Transmission Studies Of Laser Annealing In Ion-implanted Silicon-on-sapphire

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    Time-resolved optical transmission has been studied using 633 and 514 nm CW probes on ion-implantation-amorphized silicon-on-sapphire during annealing by a 10 nsec, ⊥ J/cm2 pulse at either 532 nm or 485 nm. As recrystallization sets in the transmitted signal at 514 nm rises by ⊥ 103 in ⊥ 60 nsec and provides a measure of regrowth velocity. Beyond 200 nsec the much slower transmission rise is used to provide an estimate of the Si cooling rate. The difference in transmission observed between initially crystalline and initially amorphous Si provide an estimate of the latent heat of recrystallization of the amorphous phase. © 1983

    The Initial Mass Function in disc galaxies and in galaxy clusters: the chemo-photometric picture

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    The observed brightness of the Tully-Fisher relation suggests a low stellar M/L ratio and a "bottom-light" IMF in disc galaxies, but the corresponding efficiency of chemical enrichment tends to exceed the observational estimates. Either suitable tuning of the IMF slope and mass limits or metal outflows from disc galaxies must then be invoked. A standard Solar Neighbourhood IMF cannot explain the high metallicity of the hot intra-cluster medium: a different IMF must be at work in clusters of galaxies. Alternatively, if the IMF is universal and chemical enrichment is everywhere as efficient as observed in clusters, substantial loss of metals must occur from the Solar Neighbourhood and from disc galaxies in general; a "non-standard" scenario challenging our understanding of disc galaxy formation.Comment: 6 pages, 4 figures; in Proceedings of IMF@50: the Initial Mass Function 50 years later; Corbelli, Palla and Zinnecker (eds.

    Off-Critical Logarithmic Minimal Models

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    We consider the integrable minimal models M(m,m;t){\cal M}(m,m';t), corresponding to the φ1,3\varphi_{1,3} perturbation off-criticality, in the {\it logarithmic limit\,} m,mm, m'\to\infty, m/mp/pm/m'\to p/p' where p,pp, p' are coprime and the limit is taken through coprime values of m,mm,m'. We view these off-critical minimal models M(m,m;t){\cal M}(m,m';t) as the continuum scaling limit of the Forrester-Baxter Restricted Solid-On-Solid (RSOS) models on the square lattice. Applying Corner Transfer Matrices to the Forrester-Baxter RSOS models in Regime III, we argue that taking first the thermodynamic limit and second the {\it logarithmic limit\,} yields off-critical logarithmic minimal models LM(p,p;t){\cal LM}(p,p';t) corresponding to the φ1,3\varphi_{1,3} perturbation of the critical logarithmic minimal models LM(p,p){\cal LM}(p,p'). Specifically, in accord with the Kyoto correspondence principle, we show that the logarithmic limit of the one-dimensional configurational sums yields finitized quasi-rational characters of the Kac representations of the critical logarithmic minimal models LM(p,p){\cal LM}(p,p'). We also calculate the logarithmic limit of certain off-critical observables Or,s{\cal O}_{r,s} related to One Point Functions and show that the associated critical exponents βr,s=(2α)Δr,sp,p\beta_{r,s}=(2-\alpha)\,\Delta_{r,s}^{p,p'} produce all conformal dimensions Δr,sp,p<(pp)(9pp)4pp\Delta_{r,s}^{p,p'}<{(p'-p)(9p-p')\over 4pp'} in the infinitely extended Kac table. The corresponding Kac labels (r,s)(r,s) satisfy (pspr)2<8p(pp)(p s-p' r)^2< 8p(p'-p). The exponent 2α=p2(pp)2-\alpha ={p'\over 2(p'-p)} is obtained from the logarithmic limit of the free energy giving the conformal dimension Δt=1α2α=2ppp=Δ1,3p,p\Delta_t={1-\alpha\over 2-\alpha}={2p-p'\over p'}=\Delta_{1,3}^{p,p'} for the perturbing field tt. As befits a non-unitary theory, some observables Or,s{\cal O}_{r,s} diverge at criticality.Comment: 18 pages, 5 figures; version 3 contains amplifications and minor typographical correction

    Virtual screening for inhibitors of the human TSLP:TSLPR interaction

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    The pro-inflammatory cytokine thymic stromal lymphopoietin (TSLP) plays a pivotal role in the pathophysiology of various allergy disorders that are mediated by type 2 helper T cell (Th2) responses, such as asthma and atopic dermatitis. TSLP forms a ternary complex with the TSLP receptor (TSLPR) and the interleukin-7-receptor subunit alpha (IL-7Ra), thereby activating a signaling cascade that culminates in the release of pro-inflammatory mediators. In this study, we conducted an in silico characterization of the TSLP: TSLPR complex to investigate the drugability of this complex. Two commercially available fragment libraries were screened computationally for possible inhibitors and a selection of fragments was subsequently tested in vitro. The screening setup consisted of two orthogonal assays measuring TSLP binding to TSLPR: a BLI-based assay and a biochemical assay based on a TSLP: alkaline phosphatase fusion protein. Four fragments pertaining to diverse chemical classes were identified to reduce TSLP: TSLPR complex formation to less than 75% in millimolar concentrations. We have used unbiased molecular dynamics simulations to develop a Markov state model that characterized the binding pathway of the most interesting compound. This work provides a proof-ofprinciple for use of fragments in the inhibition of TSLP: TSLPR complexation

    EWPD Constraints on Flavor Symmetric Vector Fields

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    Electroweak precision data constraints on flavor symmetric vector fields are determined. The flavor multiplets of spin one that we examine are the complete set of fields that couple to quark bi-linears at tree level while not initially breaking the quark global flavor symmetry group. Flavor safe vector masses proximate to, and in some cases below, the electroweak symmetry breaking scale are found to be allowed. Many of these fields provide a flavor safe mechanism to explain the t tbar forward backward anomaly, and can simultaneously significantly raise the allowed values of the Standard Model Higgs mass consistent with electroweak precision data.Comment: Matches version published in JHE

    Diabetes and Co-morbid Depression Among Racially Diverse, Low-Income Adults

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    Background Research suggests individuals with diabetes are twice as likely as those without diabetes to be clinically depressed. Still unknown is the relationship between diabetes and depression in socioeconomically disadvantaged populations. Purpose We examined the relationship between diabetes and depressive symptoms in a large, racially diverse, low-income cohort in the southeastern USA. Methods A total of 69,068 adults were recruited from community health centers in 12 southeastern states. A fully adjusted polytomous logistic regression model tested the relationship between demographics, lifestyle behaviors, antidepressant use, body mass index, diabetes diagnosis, diabetes duration, diabetes medication compliance, and depressive symptoms using the Centers for Epidemiological Studies Depression scale. Results Diabetes was present in 21.7% of sample. While a diabetes diagnosis was associated with having severe depressive symptoms (AOR, 1.24; 95% CI, 1.14–1.34), demographics, lifestyle behaviors, body mass index and antidepressant use were more strongly associated with severe depressive symptoms than a diabetes diagnosis. Conclusions Having diabetes was associated with the presence and severity of depressive symptoms in a large, low-income sample of racially diverse adults. However, the relationship between diabetes and depressive symptoms was weaker than in other studies with higher socioeconomic groups

    Probing for Invisible Higgs Decays with Global Fits

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    We demonstrate by performing a global fit on Higgs signal strength data that large invisible branching ratios Br_{inv} for a Standard Model (SM) Higgs particle are currently consistent with the experimental hints of a scalar resonance at the mass scale m_h ~ 124 GeV. For this mass scale, we find Br_{inv} < 0.64 (95 % CL) from a global fit to individual channel signal strengths supplied by ATLAS, CMS and the Tevatron collaborations. Novel tests that can be used to improve the prospects of experimentally discovering the existence of a Br_{inv} with future data are proposed. These tests are based on the combination of all visible channel Higgs signal strengths, and allow us to examine the required reduction in experimental and theoretical errors in this data that would allow a more significantly bounded invisible branching ratio to be experimentally supported. We examine in some detail how our conclusions and method are affected when a scalar resonance at this mass scale has couplings deviating from the SM ones.Comment: 32pp, 15 figures v2: JHEP version, ref added & comment added after Eq.
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