Directional sensitivity is one of the most important aspects of WIMP dark matter searches. Yet, making the direction of nuclear recoil visible with large target masses is a challenge. To achieve this, we are exploring a new method of detecting directions of short nuclear recoil tracks in high-pressure Xe gas, down to a few micron long, by utilizing columnar recombination. Columnar recombination changes the scintillation and ionization yields depending on the angle between a track and the electric field direction. In order to realize this, efficient cooling of electrons is essential. Trimethylamine(TMA) is one of the candidate additives to gaseous Xe in order to enhance the effect, not only by efficiently cooling the electrons, but also by increasing the amount of columnar recombination by Penning transfer. We performed a detailed simulation of ionization electrons transport created by nuclear recoils in a Xe + TMA gas mixture, and evaluated the size of the columnar recombination signal. The results show that the directionality signal can be obtained for a track longer than a few μm in some ideal cases. Although more studies with realistic assumptions are still needed in order to assess feasibility of this technique, this potentially opens a new possibility for dark matter searches.
The renormalization-scale dependence of the non-factorizable virtual corrections to Higgs boson production in weak boson fusion at next-to-next-to-leading order in perturbative QCD is unusually strong, due to the peculiar nature of these corrections. To address this problem, we compute the three-loop non-factorizable contribution to this process which accounts for the running of the strong coupling constant, and show that it stabilizes the theoretical prediction.
The ATLAS TRT barrel is a tracking drift chamber using 52,544 individual tubular drift tubes. It is one part of the ATLAS Inner Detector, which consists of three sub-systems: the pixel detector spanning the radius range 4 to 20 cm, the semiconductor tracker (SCT) from 30 to 52 cm, and the transition radiation tracker (TRT) from 56 to 108 cm. The TRT barrel covers the central pseudo-rapidity region |η|< 1, and the TRT while endcaps cover the forward and backward eta regions. These TRT systems provide a combination of continuous tracking with many measurements in individual drift tubes (or straws) and of electron identification based on transition radiation from fibers or foils interleaved between the straws themselves. This paper describes the recently-completed construction of the TRT Barrel detector, including the quality control procedures used in the fabrication of the detector.
The Accelerator Neutrino Neutron Interaction Experiment (ANNIE) aims to make a unique measurement of neutron yield from neutrino-nucleus interactions and to perform R&D for the next generation of water-based neutrino detectors. In this paper, we characterize beam-induced neutron backgrounds in the experimental hall at Fermi National Accelerator Laboratory. It is shown that the background levels are sufficiently low to allow the next stage of the experiment to proceed. These measurements are relevant to other Booster Neutrino Beam (BNB) experiments located adjacent to ANNIE Hall, where dirt neutrons and sky-shine could present similar backgrounds.
Abstract In this paper, we study in detail the phenomenology of the non-SM SU (2) V singlet Higgs boson H10 at the 14 TeV Large Hadron Collider (LHC) in the Georgi–Machacek (GM) model. We present a systematic comparison of the production mechanisms and decay modes of H10 , especially the vector-boson fusion (VBF) and gluon–gluon fusion ( gg F) production mechanisms and the decays to W + W − , ZZ , H 5 H 5 , H 3 H 3 , H3±W∓ and H30Z . After performing a comprehensive scan over the seven-dimensional parameter space of the GM model, we find that the H10→H3±W∓ , H10→H30Z and H10→H3H3 decay channels are almost excluded by the theoretical and experimental constraints, while H10 can decay into H 5 H 5 in an appreciable region of the GM parameter space. Based on the scanning results, we discuss detailedly the H10 production via gg F and VBF with subsequent decays of H10→H5H5→W+W−W+W−→l±ν(−)l±ν(−)+4jets , H10→ZZ→l+l−l+l− and H10→W+W−→e±μ∓νν¯ at the 14 TeV LHC. The integrated cross sections and some kinematic distributions of final products for both the signals at some benchmark points of the GM parameter space and the corresponding SM backgrounds are provided. If the decay to H 5 H 5 is kinematically allowed, H10 can be detected in the H10→H5H5→W+W−W+W−→l±ν(−)l±ν(−)+4jets decay channel at high-luminosity LHC unless BR(H10→H5H5) is too small or mH10 is too high. In the mass range of 2mV≲mH10<2mH5 , the vector-boson fusion is the most promising production channel in search of H10 due to the two hard tagging jets in the final state, and we may expect to discover H10 in both H10→W+W−→e±μ∓νν¯ and H10→ZZ→4l decay channels with O(102)fb−1 of data if the decay branching ratio of H10 to a pair of weak gauge bosons is sufficiently large.
Non-factorizable virtual corrections to Higgs boson production in weak boson fusion at next-to-next-to-leading order in QCD were estimated in the eikonal approximation [1]. This approximation corresponds to the expansion of relevant amplitudes around the forward limit. In this paper we compute the leading power correction to the eikonal limit and show that it is proportional to first power of the Higgs boson transverse momentum or the Higgs boson mass over partonic center-of-mass energy. Moreover, this correction can be significantly enhanced by the rapidity of the Higgs boson. For realistic weak boson fusion cuts, the next-to-eikonal correction reduces the estimate of non-factorizable contributions to fiducial cross section by O(30) percent.
The Accelerator Neutrino Neutron Interaction Experiment (ANNIE) aims to make a unique measurement of neutron yield from neutrino-nucleus interactions and to perform R&D for the next generation of water-based neutrino detectors. In this paper, we characterize beam-induced neutron backgrounds in the experimental hall at Fermi National Accelerator Laboratory. It is shown that the background levels are sufficiently low to allow the next stage of the experiment to proceed. These measurements are relevant to other Booster Neutrino Beam (BNB) experiments located adjacent to ANNIE Hall, where dirt neutrons and sky-shine could present similar backgrounds.
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