SEARCH · Searcharxiv
Search indexed arXiv papers on artificial intelligence, large language models, computer vision and robotics. Read source abstracts and follow links to arXiv.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
We present an overview of the measurements of the like-sign dimuon charge asymmetry by the DO Collaboration at the Fermilab Tevatron proton-antiproton Collider. The results differ from the Standard Model prediction of CP violation in mixing and interference of B^0 and B^0_s by 3.6 standard deviations.
In the Minimal Supersymmetric extension of the Standard Model or MSSM, the lighter Higgs boson has a rather large mass, $M_h\approx 125$ GeV. Together with the non-observation of superpartners at the LHC, this suggests that the SUSY-breaking scale is rather high, $M_S > 1$ TeV. This implies a dramatic simplification of the MSSM Higgs sector that is summarised here.
Searches for new fermionic states heavier than the top quark are being pursued by the CMS & ATLAS collaborations, pushing the mass bounds towards the TeV scale. Although a chiral fourth generation of quarks is now excluded by the LHC results, models going beyond the Standard Model predict the existence of heavy vector-like top partners as potential smoking gun signatures. Relying on a model-independent parametrisation, we present the first results of a dedicated software called XQCAT (eXtra Quark Combined Analysis Tool), which recasts publicly available experimental data from direct and Supersymmetry inspired searches and computes the exclusion confidence level for New Physics scenarios with one or multiple top partners. The mass limits set on a T singlet scenario with general coupling assumptions are briefly discussed in this framework.
PandaX is a large upgradable liquid-xenon detector system that can be used for both direct dark-matter detection and $^{136}$Xe double-beta decay search. It is located in the Jinping Deep-Underground Laboratory in Sichuan, China. The detector operates in dual-phase mode, allowing detection of both prompt scintillation, and ionization charge through proportional scintillation. The central time projection chamber will be staged, with the first stage accommodating a target mass of about 120\,kg. In stage II, the target mass will be increased to about 0.5\,ton. In the final stage, the detector can be upgraded to a multi-ton target mass. In this paper a detailed description of the stage-I detector design and performance results established during the commissioning phase is presented.
We present the Flowgen tool, which generates flowcharts from annotated C++ source code. The tool generates a set of interconnected high-level UML activity diagrams, one for each function or method in the C++ sources. It provides a simple and visual overview of complex implementations of numerical algorithms. Flowgen is complementary to the widely-used Doxygen documentation tool. The ultimate aim is to render complex C++ computer codes accessible, and to enhance collaboration between programmers and algorithm or science specialists. We describe the tool and a proof-of-concept application to the VINCIA plug-in for simulating collisions at CERN's Large Hadron Collider.
The SNO+ experiment, currently undergoing commissioning, will be a large scale liquid scintillator detector capable of studying a variety of physics topics, with the highest priority being a sensitive search for neutrinoless double beta decay. The collaboration has recently decided to use 130Te as the candidate isotope for this search, having developed a new approach to the purification and loading of tellurium into liquid scintillator. An initial Phase I demonstrator with a 0.3% Te loading is expected to reach sensitivities to Majorana neutrino masses approaching the top of the inverted neutrino mass hierarchy. If successful, there is significant scope for further enhancements that could lead to measurements covering the vast majority of the inverted hierarchy range with high sensitivity.
The latest results of the two HERA collaborations, H1 and ZEUS, are presented. They include the most recent measurements of the longitudinal structure funcion FL from both collaborations. Also presented are high Q2 measurements from the ZEUS collaboration in the high Bjorken x region up to values of x = 1.
The study of $C\!P$ violation in decays of neutral $B$ mesons provides an important test of the Standard Model (SM) predictions and it is a sensitive probe to search for non-SM physics. In these proceedings I present measurements of $C\!P$ violation in the neutral $B$ meson system. The discussed analyses are based on $pp$-collision data corresponding to an integrated luminosity of 1 $\mathrm{fb}^{-1}$ or 3 $\mathrm{fb}^{-1}$ recorded by the LHCb experiment.
Under the hypothesis that the MSSM neutralino accounts for the observed dark matter density, we investigate how light this particle is still allowed to be after the latest LHC data. In particular, we discuss the impact of searches for events with multiple taus and missing transverse momentum, which are a generic prediction of the light neutralino scenario.
Constraints are set on the Higgs boson decay width, Gamma_H, using off-shell production and decay to ZZ in the four-lepton (4l), or two-lepton-two-neutrino (2l2nu) final states. The analysis is based on the data collected in 2012 by the CMS experiment at the LHC, corresponding to an integrated luminosity L = 19.7 fb^{-1} at sqrt(s) = 8 TeV. A maximum-likelihood fit of invariant mass and kinematic discriminant distributions in the 4l case and of transverse mass or missing energy distributions in the 2l2nu case is performed. The result of it, combined with the 4l measurement near the resonance peak, leads to an upper limit on the Higgs boson width of Gamma_H < 4.2 x Gamma_H^SM at the 95% confidence level, assuming Gamma_H^SM = 4.15 MeV.
We report on the search for the decay $Υ(1S) \to γA^0$, $A^0 \to gg$ or $s\bar s$, where $A^0$ is the pseudoscalar light Higgs boson predicted by the next-to-minimal supersymmetric standard model. A sample of $\sim 18 \times 10^6$ $Υ(1S)$ resonances, produced in the BaBar experiment via $e^+e^- \to Υ(2S) \to π^+π^-Υ(1S)$, is used for this search. No significant signal has been found, and upper limits at the $90\%$ of confidence level are set on the product branching fraction of the process.
A correction of the neutrinoless 2\b{eta}-decay model was proposed which predicted a shift of the 2\b{eta}0ν-signal from the Q value (2\b{eta}-decay energy). The shifts were calculated for 76Ge (\D{elta}E=-2.6 keV), 100Mo (\D{elta}E=-4.7 keV), 130Te (\D{elta}E=-3.7 keV). The calculations for 76Ge were in agreement with H-M results. A reanalysis of the published Quoricino data (a search for a 2\b{eta}0ν-decay of 130Te) was performed. It indicated a presence of a signal at E = 2523.5 keV \a{pprox} Q(130Te)-3.7 keV. It could be attributed to the 130Te neutrinoless 2\b{eta}-decay with T1/2 = (5.7+-2.3)10^23 y. A comparison of the H-M and Quoricino data has strongly supported the experimental observation of the 2\b{eta}0ν-decay process and a validity of the proposed correction.
I summarize the status of the inclusive SUSY searches conducted by the ATLAS and CMS experiments using the 20 fb-1 of 8 TeV LHC data in the all inclusive, 0 lepton, >=1 lepton and >=2 lepton final states. Current searches show that data are consistent with the SM. The impact of this consistency was explored on a rich variety of SUSY scenarios and simplified models, examples of which I present here.
The histogram is an analysis tool in widespread use within many sciences, with high energy physics as a prime example. However, there exists an inherent bias in the choice of binning for the histogram, with different choices potentially leading to different interpretations. This paper aims to eliminate this bias using two "debinning" algorithms. Both algorithms generate an observed cumulative distribution function from the data, and use it to construct a representation of the underlying probability distribution function. The strengths and weaknesses of these two algorithms are compared and contrasted. The applicability and future prospects of these algorithms is also discussed.
The characteristics of extensive air showers are sensitive to the details of hadronic interactions at energies and in kinematic regions beyond those tested by human-made accelerators. Uncertainties on extrapolations of the hadronic interaction models in these regions hamper the interpretation of the ultra high energy cosmic ray data in terms of primary mass composition. We report on how the Pierre Auger Observatory is able to constrain the hadronic interaction models by measuring the muon content and muon production depth of air showers and also by measuring the proton-air cross section for particle production at a center-of-mass energy per nucleon of 57 TeV.
The mean energy $W$ required to produce an ion pair in molecular hydrogen has been obtained for protons in the energy range between 1 MeV and 4.5 MeV. The W values were derived from the existing experimental data on elastic {\it $π^-$p} scattering at the beam energy of 40 GeV. In the experiment, the ionization chamber IKAR filled with hydrogen at a pressure of 10 at served simultaneously as a gas target and a detector for recoil protons. For selected events of elastic scattering, the ionization yield produced by recoil protons was measured in IKAR, while the energy was determined kinematically through the scattering angles of the incident particles measured with a system of multi-wire proportional chambers. The ionization produced by $α$-particles from $α$-sources of $^{234}$U deposited on the chamber electrodes was used for absolute normalization of the W values. The energy dependence of $W$ for protons in H$_2$ shows an anomalous increase of $W$ with increasing energy in the measured energy range. At the energy of 4.76 MeV, the ionization yield for alpha particles is by 2\% larger than that for protons.
A lepton collider in the multi-TeV range has the potential to measure the trilinear Higgs self-coupling constant $λ_{hhh}$ via the W-fusion mode $\ell^+\ell^- \rightarrow ν_\ell \barν_\ell h h$. In this paper we do a generator-level study to explore how center-of-mass energy spread, cone size, tracking resolution, and collision energy range affect how precisely a muon collider can measure $λ_{hhh}$ in comparison to an $e^+e^-$ collider. The smaller spread in center-of-mass energy and higher energy range of a muon collider improve cross section while the larger cone required to reduce beam-induced background hinders detection of double-Higgs events. Our results motivate a more detailed study of a multi-TeV muon collider and innovative detector and analysis technologies required for background rejection and precision measurement.
The design, construction and testing of neutrino detector prototypes at CERN are ongoing activities. This document reports on the design of solid state baby MIND and TASD detector prototypes and outlines requirements for a test beam at CERN to test these, tentatively planned on the H8 beamline in the North Area, which is equipped with a large aperture magnet. The current proposal is submitted to be considered in light of the recently approved projects related to neutrino activities with the SPS in the North Area in the medium term 2015-2020.