537 research outputs found

    Smoking Guns for On-Shell New Physics at the LHC

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    Using Tevatron bounds we derive upper limits on the LHC Higgs production rate under the assumption that no beyond the Standard Model (BSM) particles are being produced near their mass shell. A violation of these limits would constitute a smoking gun for light BSM particles. Furthermore, we demonstrate how R_T, the ratio of the partially integrated Higgs transverse momentum distribution to the inclusive rate, can also be used as a probe of light BSM particles. This ratio is insensitive to heavy virtual effects and can be well-approximated by its SM value, i.e. it is model independent. The perturbative expansion for R_T has reduced renormalization scale dependence, at the order of 5% at next-to-leading order in QCD, due to a cancellation of Wilson coefficients. A deviation from the SM value implies that light BSM particles are being produced near their mass shell. We discuss a possible loophole to this conclusion, namely the existence of a non-perturbative, CP violating sector that couples to the Higgs. We use a toy model with colored scalars to demonstrate how the model independent prediction for R_T is approached as the mass of the scalar becomes large.Comment: 4 pages, 4 figure

    Diagnostic accuracy of haemophilia early arthropathy detection with ultrasound (HEAD-US): A comparative magnetic resonance imaging (MRI) study

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    Background. Repeated haemarthroses affect approximately 90% of patients with severe haemophilia and lead to progressive arthropathy, which is the main cause of morbidity in these patients. Diagnostic imaging can detect even subclinical arthropathy changes and may impact prophylactic treatment. Magnetic resonance imagining (MRI) is generally the gold standard tool for precise evaluation of joints, but it is not easily feasible in regular follow-up of patients with haemophilia. The development of the standardized ultrasound (US) protocol for detection of early changes in haemophilic arthropathy (HEAD-US) opened new perspectives in the use of US in management of these patients. The HEAD-US protocol enables quick evaluation of the six mostly affected joints in a single study. The aim of this prospective study was to determine the diagnostic accuracy of the HEAD-US protocol for the detection and quantification of haemophilic arthropathy in comparison to the MRI. Patients and methods. The study included 30 patients with severe haemophilia. We evaluated their elbows, ankles and knees (overall 168 joints) by US using the HEAD-US protocol and compared the results with the MRI using the International Prophylaxis Study Group (IPSG) MRI score. Results. The results showed that the overall HEAD-US score correlated very highly with the overall IPSG MRI score (r = 0.92). Correlation was very high for the evaluation of the elbows and knees (r 48 0.95), and slightly lower for the ankles (r 48 0.85). Conclusions. HEAD-US protocol proved to be a quick, reliable and accurate method for the detection and quantification of haemophilic arthropathy

    Determining γ\gamma using B±DK±B^\pm \to D K^\pm with multibody D decays

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    We propose a method for determining γ\gamma using B±DK±B^\pm\to D K^\pm decays followed by a multibody DD decay, such as DKSππ+D \to K_S \pi^-\pi^+, DKSKK+D \to K_S K^-K^+ and DKSππ+π0D \to K_S \pi^-\pi^+\pi^0. The main advantages of the method is that it uses only Cabibbo allowed DD decays, and that large strong phases are expected due to the presence of resonances. Since no knowledge about the resonance structure is needed, γ\gamma can be extracted without any hadronic uncertainty.Comment: 17 pages, 1 figur

    Wine glass size and wine sales: A replication study in two bars

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    Objective. Wine glass size may influence perceived volume and subsequently purchasing and consumption. Using a larger glass to serve the same portions of wine was found to increase wine sales by 9.4% (95% CI: 1.9, 17.5) in a recent study conducted in one bar. The current study aimed to replicate this previous work in two other bars using a wider range of glass sizes. To match the previous study, a repeated multiple treatment reversal design, during which wine was served in glasses of the same design but different sizes, was used. The study was conducted in two bars in Cambridge, England, using glass sizes of 300ml, 370ml, 510ml (Bar 1) and 300ml and 510ml (Bar 2). Customers purchased their choice of a 750ml bottle, or standard UK measures of 125ml, 175ml or 250ml of wine, each of which was served with the same glass. Results. Bar 1: Daily wine volume purchased was 10.5% (95% CI: 1.0, 20.9) higher when sold in 510ml compared to 370ml glasses; but sales were not significantly higher with 370ml vs. 300ml glasses (6.5%, 95% CI: -5.2, 19.6). Bar 2: findings were inconclusive as to whether daily wine purchased differed when using 510ml vs. 300ml glasses (-1.1%, 95% CI: -12.6, 11.9). These results provide a partial replication of previous work showing that introducing larger glasses (without manipulating portion size) increases purchasing. Understanding the mechanisms by which wine glass size influences consumption may elucidate when the effect can be expected and when not.The research reported in this publication was funded by the Department of Health Policy Research Programme (http://prp.dh.gov.uk/) (Policy Research Unit in Behaviour and Health [PR-UN-0409-10109])

    Higgs After the Discovery: A Status Report

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    Recently, the ATLAS and CMS collaborations have announced the discovery of a 125 GeV particle, commensurable with the Higgs boson. We analyze the 2011 and 2012 LHC and Tevatron Higgs data in the context of simplified new physics models, paying close attention to models which can enhance the diphoton rate and allow for a natural weak-scale theory. Combining the available LHC and Tevatron data in the ZZ* 4-lepton, WW* 2-lepton, diphoton, and b-bbar channels, we derive constraints on the effective low-energy theory of the Higgs boson. We map several simplified scenarios to the effective theory, capturing numerous new physics models such as supersymmetry, composite Higgs, dilaton. We further study models with extended Higgs sectors which can naturally enhance the diphoton rate. We find that the current Higgs data are consistent with the Standard Model Higgs boson and, consequently, the parameter space in all models which go beyond the Standard Model is highly constrained.Comment: 37 pages; v2: ATLAS dijet-tag diphoton channel added, dilaton and doublet-singlet bugs corrected, references added; v3: ATLAS WW channel included, comments and references adde

    Advancing newborn health: The Saving Newborn Lives initiative

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    Until recently, newborn health was virtually absent from the global health agenda. Now, assistance agencies, national governments and non-governmental organisations are increasingly addressing this previously neglected issue of close to four million newborns dying every year. The experience of the Saving Newborn Lives initiative documents some of the progress that has been made and the challenges and opportunities that lie ahead. Since the start of the initiative in 2000, targeted research, focused on overcoming the key barriers to improved newborn survival, has demonstrated low-cost, community-based interventions and strategies that can significantly reduce newborn mortality. Building on what has been learned from this and other efforts to date, the challenge now is to reach the millions of newborns still at risk

    The Discovery Potential of a Super B Factory

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    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.Comment: 476 pages. Printed copies may be obtained by request to [email protected] . arXiv admin note: v2 appears to be identical to v

    Vacuum Instabilities with a Wrong-Sign Higgs-Gluon-Gluon Amplitude

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    The recently discovered 125 GeV boson appears very similar to a Standard Model Higgs, but with data favoring an enhanced h to gamma gamma rate. A number of groups have found that fits would allow (or, less so after the latest updates, prefer) that the h-t-tbar coupling have the opposite sign. This can be given meaning in the context of an electroweak chiral Lagrangian, but it might also be interpreted to mean that a new colored and charged particle runs in loops and produces the opposite-sign hGG amplitude to that generated by integrating out the top, as well as a contribution reinforcing the W-loop contribution to hFF. In order to not suppress the rate of h to WW and h to ZZ, which appear to be approximately Standard Model-like, one would need the loop to "overshoot," not only canceling the top contribution but producing an opposite-sign hGG vertex of about the same magnitude as that in the SM. We argue that most such explanations have severe problems with fine-tuning and, more importantly, vacuum stability. In particular, the case of stop loops producing an opposite-sign hGG vertex of the same size as the Standard Model one is ruled out by a combination of vacuum decay bounds and LEP constraints. We also show that scenarios with a sign flip from loops of color octet charged scalars or new fermionic states are highly constrained.Comment: 20 pages, 8 figures; v2: references adde
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