Extending the LHC Reach for New Physics with Sub-Millimeter Displaced Vertices

Particles with a sub-millimeter decay length appear in many models of physics beyond the Standard Model. However, their longevity has been often ignored in their LHC searches and they have been regarded as promptly-decaying particles. In this letter, we show that, by requiring displaced vertices on top of the event selection criteria used in the ordinary search strategies for promptly-decaying particles, we can considerably extend the LHC reach for particles with a decay length of $\gtrsim 100~\mu{\rm m}$. We discuss a way of reconstructing sub-millimeter displaced vertices by exploiting the same technique used for the primary vertex reconstruction on the assumption that the metastable particles are always pair-produced and their decay products contain high-$p_{\rm T}$ jets. We show that, by applying a cut based on displaced vertices on top of standard kinematical cuts for the search of new particles, the LHC reach can be significantly extended if the decay length is $\gtrsim 100~\mu{\rm m}$. In addition, we may measure the lifetime of the target particle through the reconstruction of displaced vertices, which plays an important role in understanding the new physics behind the metastable particles.Comment: 18 pages, 6 figure

Scalar Transfer across a Turbulent/non-turbulent Interface in a Planar Jet

This fluid dynamics video is an entry for the Gallery of Fluid Motion of the 66th Annual Meeting of the APS-DFD. In this video, the scalar transfer across the turbulent/non-turbulent (T/NT) interface in a planar jet is investigated by using a direct numerical simulation. Visualization of the scalar flux across the T/NT interface shows that the diffusive species premixed in the ambient flow is transferred into the turbulent region mainly across the leading edge (Here, the leading edge is the T/NT interface across which the turbulent fluid turns into the non-turbulent fluid in the streamwise direction).Comment: The fluid dynamics video for an entry for the Gallery of Fluid Motion of the 66th Annual Meeting of the APS-DFD is include

Superconducting Properties and Microstructure in Dilute Copper Alloys Containing Small Amounts of V_3Ga Particles(Metallurgy)

The superconducting properties (T_c and J_c) were investigated by the resistivity measurement, and the structure was observed by a transmission electron microscopy in the dilute copper alloys containing small amounts of V_3Ga particles prepared by quenching from the liquid state and aging. No superconductivity could be observed at 4.2 K in as-quenched and/or in overaged samples. The highest T_ (=12.5 K), T_ (=9.6 K), and J_c (=525 A/cm^2) were obtained by aging at 700℃ for 96 h and corresponded with the structure of fine V_3Ga precipitates dispersed homogeneously in the copper matrix. Therefore, it is concluded that superconductivity in these alloys results from the superconducting path due to the proximity effect of the superconducting V_3Ga particles

Searching for Metastable Particles with Sub-Millimeter Displaced Vertices at Hadron Colliders

A variety of new-physics models predict metastable particles whose decay length is $\lesssim 1$ mm. Conventional displaced-vertex searches are less sensitive to this sub-millimeter decay range, and thus such metastable particles have been looked for only in usual prompt decay searches. In this paper, we show that an additional event-selection cut based on the vertex reconstruction using charged tracks considerably improves the sensitivity of ordinary searches which rely only on kinematic selection criteria, for particles with a decay length of $\gtrsim 100$ $\mu \text{m}$. To that end, we consider a metastable gluino as an example, and study the impact of this new event-selection cut on gluino searches at the LHC by simulating both the signal and Standard Model background processes. Uncertainty of the displaced-vertex reconstruction due to the limited resolution of track reconstruction is taken into account. We also discuss possibilities for optimization of the kinematic selection criteria, which takes advantage of significant reduction of background through the requirement of displaced vertices. In addition, we demonstrate that using the method discussed in this paper it is possible to measure the lifetime of metastable particles with an ${\cal O}(1)$ accuracy at the high-luminosity LHC. Implications for a future 100 TeV collider are also studied, where produced particles tend to be more boosted and thus it is easier to detect the longevity of metastable particles.Comment: 55 pages, 24 figure

Apparent stratospheric ozone loss rate over Eureka in 1994/95, 1995/96, and 1996/97 inferred from ECC ozonesonde observations

Many ECC-type ozonesondes were launched at the Canadian Arctic Eureka observatory(80°N , 86°W ), one of the most northern stations in the Arctic, during winters from 1993/94 to 2001/02, and the temporal evolutions of the vertical ozone profiles were obtained in detail. The lower stratospheric temperature over Eureka was very low inside the polar vortex and the largest ozone loss was observed in 1999/2000, as reported in a previous paper. Similarly, Eureka was often or persistently inside the vortex in the lower stratosphere(around the 470K isentropic surface level) in the winters of 1994/95, 1995/96, and 1996/97. Very low temperatures were observed inside the vortex in the lower stratosphere over Eureka, as indicated by detection of PSCs by Mie lidar. Observations of tracers(N_2O, total reactive nitrogen species(NOy), and others) inside the vortex during these winters using an ER-2 aircraft and balloons indicated that the effect of air parcel mixing across the vortex edge was minimal, based on the tracer-tracer relationship(e.g., Y. Kondo et al.; J. Geophys. Res., 104D, 8215, 1999). Therefore, significant decreases of the in-travortex ozone mixing ratio in the lower stratosphere were considered to be chemical ozone losses due to chlorine activation of PSCs following diabatic descent. The apparent ozone loss rate inside the vortex over Eureka was estimated for each year. The rates ranged from 0.01 to 0.03ppmv/day, less than that observed in 1999/2000(0.04ppmv/day). The observations were conducted at a single station; however, the apparent ozone loss rate over Eureka inside the vortex each year agrees with loss rates obtained in other studies

Scores of Child–Pugh Classification Impact Overall Survival After Stereotactic Body Radiation Therapy for Primary and Metastatic Liver Tumors

BackgroundStereotactic body radiotherapy (SBRT) delivers high-dose radiation to tumor tissues in few fractions, thereby reducing radiation damage to at-risk organs. There are more potential effects of SBRT owing to the higher biological equivalent dose delivered. Herein, we retrospectively analyzed its effectiveness and toxicity at our institution.MethodsData from patients with hepatocellular carcinoma (HCC; n = 10) and liver metastases (n = 10) who underwent SBRT (total dose of 30–50 Gy in 5–10 fractions) between 2013 and 2016 were analyzed. Adverse events were recorded at the end of RT, 6 months after treatment, or upon death. Overall survival (OS) was calculated according to the biological effective dose (BED α/β = 10) and liver function (Child–Pugh [CP] classification 5 or 6 vs. 7 or 8) after SBRT, using Kaplan–Meier analyses.ResultsOf the 20 patients, 6 declined the CP classification score after SBRT; grade 3 adverse events were not seen in any patient. A higher OS rate was seen in patients receiving a higher BED and in those with better CP classification after SBRT. Kaplan–Meier survival analysis yielded a median OS of 401 days and 1- and 2-year OS of 45% and 15%, respectively.ConclusionThe higher BED was significantly associated with tumor control, and there were no differences in the tumor control rate between HCC and metastatic tumors. Changes in CP scores after SBRT also affected the survival rate. Good liver function may permit multiple rounds of SBRT

AJK2011-21015 CHARACTERISTICS OF THE SCALAR FIELD IN A TURBULENT LIQUID JET AND A FUNDAMENTAL STUDY ON THE MICRO SCALE CONCENTRATION MEASUREMENTS BY THE OPTICAL FIBER LIF METHOD

ABSTRACT In this study, the characteristics of the scalar field in an axisymmetric turbulent water jet are investigated experimentally. In the experiments, the axial velocity, the concentration of the dye solution and the temperature of the fluid are measured by the hot-film probe, the fiber sensor and the cold-firm probe, respectively. In particular, the difference of statistics between scalars (concentration and temperature) with the different molecular diffusion coefficients is discussed. The Schmidt number of the diffusing matter is 3,800, and the Prandtl number of temperature is 7. As regarding the mean values, the r.m.s values and distribution of PDF, we cannot find any difference between the concentration field and temperature field. However, in the spectrum, it is found that the temperature spectrum shows the -5/3 law almost in the same range as the velocity spectrum, on the other hand, the concentration spectrum shows the -5/3 law in the wider range than the velocity spectrum. This means that the shape of spectrum depends on the diffusion coefficient. In order to make the higher resolution measurement of concentration, a new optical probe based on the LIF method is designed. This probe consists of the two optical fibers, the tip of which is processed like the shape of a lens. By the effect of lens, the laser beam can be focused on the narrower area in comparison with the past LIF measurements. In the present design, the width of focus of laser beam is set to 0.6 micrometers, and the focal length is set to 7.3mm. It is shown that this probe has the resolution less than the Batchelor scale at in the condition of present jet diffusion field (d=4mm, Re=20,000). Further, a new system to adjust the position of the optic fiber probe exquisitely is developed. INTRODUCTION There are many practical problems in the industrial and natural flow fields that the diffusing matter are mixed. In this study, we pay a special attention to the diffusion fields of scalars (concentration and temperature) in the turbulent liquid jet. In the liquid phase, it is usually known that the Schmidt number of the diffusing matter (or the Prandtl number in case of temperature) is larger than 1, so that the scalar fields have been crucially influenced by the velocity field. In this case, it is useful to investigate the relations between the velocity and scalar statistics to understand the mixing process of the scalar in the turbulent liquid flows. With regard to the measurements of high Schmidt number matter, the concentrations of the fluorescent dye or the kalium chloride have been often measured by Laser-Induced Fluorescence (LIF) method or the electrode method. However seeing the past reports, in case of the flows with the mean shear, there are still large scattering of the data for the scalar statistics, and so the reliable turbulent statistics are keenly required. On the other hand, the similarity theory of turbulent scalar field shows that for the scalar field of high Schmidt number and high Reynolds number, there exist the statistical universal ranges called the "viscous convective subrange" and the "viscous diffusive subrange" in the space smaller than the Kolmogorov scale (which is the smallest velocity fluctuatio