From Higgs measurements to constraints on new physics with Lilith

The properties of the observed Higgs boson with mass around 125 GeV are constrained by a wealth of experimental results targeting different combinations for the production and decay of a Higgs boson. In order to assess the compatibility of a non-Standard Model-like Higgs boson with all available results, we present Lilith, a new public tool that makes use of signal strength measurements performed at the LHC and the Tevatron.Comment: 4 pages, 3 figures. Presented at the 2nd Toyama International Workshop on "Higgs as a Probe of New Physics 2015" (HPNP2015), Toyama, Japan, February 11-15, 2015. To appear in the proceeding

Lilith: a tool for constraining new physics from Higgs measurements

The properties of the observed Higgs boson with mass around 125 GeV can be affected in a variety of ways by new physics beyond the Standard Model (SM). The wealth of experimental results, targeting the different combinations for the production and decay of a Higgs boson, makes it a non-trivial task to assess the compatibility of a non-SM-like Higgs boson with all available results. In this paper we present Lilith, a new public tool for constraining new physics from signal strength measurements performed at the LHC and the Tevatron. Lilith is a Python library that can also be used in C and C++/ROOT programs. The Higgs likelihood is based on experimental results stored in an easily extensible XML database, and is evaluated from the user input, given in XML format in terms of reduced couplings or signal strengths. The results of Lilith can be used to constrain a wide class of new physics scenarios.Comment: 57 pages, 11 figures; v2: minor corrections, references added; v3: extended discussions on the validity of the approach, matches the published version; the code can be found at http://lpsc.in2p3.fr/projects-th/lilith

Baryonic R-parity violation and its running

Baryonic R-parity violation arises naturally once Minimal Flavor Violation (MFV) is imposed on the supersymmetric flavor sector at the low scale. At the same time, the yet unknown flavor dynamics behind MFV could take place at a very high scale. In this paper, we analyze the renormalization group (RG) evolution of this scenario. We find that low-scale MFV is systematically reinforced through the evolution, with the R-parity violating couplings exhibiting infrared fixed points. Intriguingly, we also find that if holomorphy is imposed on MFV at some scale, it is preserved by the RG evolution. Furthermore, low-scale holomorphy is a powerful infrared attractor for a large class of non-holomorphic scenarios. Therefore, supersymmetry with minimally flavor violating baryon number violation at the low scale, especially in the holomorphic case but not only, is viable and resilient under the RG evolution, and should constitute a leading contender for the physics beyond the Standard Model waiting to be discovered at the LHC.Comment: 20 pages, 4 figures, to appear in JHE

A new insight into the phase transition in the early Universe with two Higgs doublets

We study the electroweak phase transition in the alignment limit of the CP-conserving two-Higgs-doublet model (2HDM) of Type I and Type II. The effective potential is evaluated at one-loop, where the thermal potential includes Daisy corrections and is reliably approximated by means of a sum of Bessel functions. Both 1-stage and 2-stage electroweak phase transitions are shown to be possible, depending on the pattern of the vacuum development as the Universe cools down. For the 1-stage case focused on in this paper, we analyze the properties of phase transition and discover that the field value of the electroweak symmetry breaking vacuum at the critical temperature at which the first order phase transition occurs is largely correlated with the vacuum depth of the 1-loop potential at zero temperature. We demonstrate that a strong first order electroweak phase transition (SFOEWPT) in the 2HDM is achievable and establish benchmark scenarios leading to different testable signatures at colliders. In addition, we verify that an enhanced triple Higgs coupling (including loop corrections) is a typical feature of the SFOPT driven by the additional doublet. As a result, SFOEWPT might be able to be probed at the LHC and future lepton colliders through Higgs pair production.Comment: 43 pages, 18 figures, minor revision and match to the published versio

Status of Higgs couplings after Run-1 of the LHC using Lilith 1.0

We provide an update of the global fits of the couplings of the 125.5 GeV Higgs boson using all publicly available experimental results from Run-1 of the LHC as per Summer 2014. The fits are done by means of the new public code Lilith 1.0. We present a selection of results given in terms of signal strengths, reduced couplings, and for the Two-Higgs-Doublet Models of Type I and II.Comment: 12 pages, 4 figure

Product recalls: The effects of industry, recall strategy and hazard, on shareholder wealth

The purpose of this paper is to provide insights into the effects of product recalls on shareholder wealth of manufacturing firms in different supply chains. Previous research examining this phenomenon is largely uni-sectorial and/or does not consider the interplay of hazard, recall strategy and sector. By utilizing the event study method, this study examines investors\u27 reactions to key product recall characteristics: industry, recall strategy and hazard level, on a cross-industry sample of 296 product recall announcements. The results show a significant negative reaction of share values to product recalls and significant differences between industry type and hazard levels. More regulated and stringent supply chains, such as the automotive and pharmaceutical, showed statistically significant losses in share price. The results show that industry sector and level of hazard associated with defective products are significant factors impacting the shareholder wealth of manufacturing firms. Contrary to some studies, the impact of recall strategy was not confirmed, although proactive recall strategies led, in some cases, to an increase in share price. Further research would benefit from more detailed investigation of recall strategies on the value of companies in specific sectors, particularly ones which are susceptible to frequent and costly product recalls

Characterising the 750 GeV diphoton excess

We study kinematic distributions that may help characterise the recently observed excess in diphoton events at 750 GeV at the LHC Run 2. Several scenarios are considered, including spin-0 and spin-2 750 GeV resonances that decay directly into photon pairs as well as heavier parent resonances that undergo three-body or cascade decays. We find that combinations of the distributions of the diphoton system and the leading photon can distinguish the topology and mass spectra of the different scenarios, while patterns of QCD radiation can help differentiate the production mechanisms. Moreover, missing energy is a powerful discriminator for the heavy parent scenarios if they involve (effectively) invisible particles. While our study concentrates on the current excess at 750 GeV, the analysis is general and can also be useful for characterising other potential diphoton signals in the future.Comment: 24 pages, 11 figures, 1 table; v2: references added, version to appear in JHE

A prospective randomised trial comparing plastic and uncovered self-expanding metal stents for palliation of symptomatic jaundice in patients with malignant distal biliary obstruction

The aim of this study was to determine the safety and clinical effectiveness of 10Fr plastic biliary stents compared to uncovered self-expanding metal stents (SEMS) for palliative treatment of patients with inoperable malignant distal biliary obstruction in a public hospital in South Africa. Methods: From January 2009 to December 2013, 40 patients who were admitted to a tertiary academic centre because of distal malignant biliary obstruction were enrolled in a prospective randomised study. Patients were randomly assigned to receive either an uncovered SEMS or a plastic stent deployed through the biliary stricture during endoscopic retrograde cholangiopancreatography. Results: Patient survival time in the two groups did not differ significantly (median: SEMS - 114 days; plastic - 107 days) (p=0.181). Stent failure was more common in the plastic stent group (7/19 vs. 1/20) (p=0.043). The results became significant after 6 months of follow up. There was no significant difference between the two groups in the incidence of serious adverse events. Conclusions: SEMS had a longer duration of patency than plastic stents, which favours their use in the palliative treatment of patients with biliary obstruction due to distal malignant biliary obstruction