117982931
Three-particle templates for a boosted Higgs boson
We explore the ability of three-particle templates to distinguish color neutral objects from QCD background. This method is particularly useful to identify the standard model Higgs, as well as other massive neutral particles. Simple cut-based analysis in the overlap distributions of the signal and background is shown to provide a significant rejection power. By combining with other discriminating variables, such as planar flow, and several variables that depend on the partonic template, three-particle templates are used to characterize the influence of gluon emission and color flow in collider events. The performance of the method is discussed for the case of a highly boosted Higgs in association with a leptonically-decaying W boson.
10444896
Active cooling control of the CLEO detector using a hydrocarbon coolant farm
Abstract We describe a novel approach to particle-detector cooling in which a modular farm of active coolant-control platforms provides independent and regulated heat removal from four recently upgraded subsystems of the CLEO detector: the ring-imaging Cherenkov detector, the drift chamber, the silicon vertex detector, and the beryllium beam pipe. We report on several aspects of the system: the suitability of using the aliphatic-hydrocarbon solvent PF TM -200IG as a heat-transfer fluid, the sensor elements and the mechanical design of the farm platforms, a control system that is founded upon a commercial programmable logic controller employed in industrial process-control applications, and a diagnostic system based on virtual instrumentation. We summarize the system's performance and point out the potential application of the design to future high-energy physics apparatus.
53394613
Warped Extra Dimensional Benchmarks for Snowmass 2013
The framework of a warped extra dimension with the Standard Model (SM) fields propagating in it is a very well-motivated extension of the SM since it can address both the Planck-weak and flavor hierarchy problems of the SM. We consider signals at the 14 and 33 TeV large hadron collider (LHC) resulting from the direct production of the new particles in this framework, i.e.,Kaluza-Klein (KK) excitations of the SM particles. We focus on spin-1 (gauge boson) and spin-2 (graviton) KK particles and their decays to top/bottom quarks (flavor-conserving) and W/Z and Higgs bosons, in particular. We propose two benchmarks for this purpose, with the right-handed (RH) or LH top quark, respectively, being localized very close to the TeV end of the extra dimension. We present some new results at the 14 TeV (with 300 fb$^-1$ and 3000 fb$^-1$) and 33 TeV LHC. We find that the prospects for discovery of these particles are quite promising, especially at the high-luminosity upgrade.
54853460
Study of the standard model Higgs boson partial widths and branching fractions
The discovery of the Higgs boson, with a mass known to be better than the percent level, enables precision Higgs boson analyses for the first time. Toward this goal, we define an expansion formalism of the Higgs boson partial widths and branching fractions that facilitates such studies. This expansion yields the observables as a perturbative expansion around reference values of Standard Model input observables (quark masses, QCD coupling constant, etc.). We compute the coefficients of the expansion using state-of- the-art results. We also study the various sources of uncertainties in computing the partial widths and branching fractions more precisely. We discuss the impact of these results with efforts to discern new physics through precision Higgs boson studies. With the discovery of the Higgs boson (1), particle physics is entering a new era of precision studies of the Higgs sector. The observables are many and include the Higgs boson mass, its total decay width, its spin, its decay branching fractions to Standard Model (SM) particles, its possible decay branching fractions to other exotic final states, and its various production rates at colliders. All of these observables will be studied carefully in time. The theory under primary consideration in this article is the Standard Model. The subpercent-level determination of the Higgs boson mass now enables a complete set of input observables whereby any perturbative high-energy observ- able involving the Higgs boson can be predicted. In this article, our focus is on the careful exposition of the decay partial widths and branching fractions of a SM Higgs boson with mass near 126 GeV. Our goal is to provide state-of-the-art formulas that can be used in any precision electroweak analysis to investigate compatibility of the data with the SM predictions in these most fundamental and sensitive observables. Other calculations exist in the literature, 1 most notably from the computer program HDECAY (2); however, we wish to provide an independent calculation that includes the latest advances and allows us to vary the renormalization scale in all parts of the computations. This flexibility will be useful in later discussions regarding uncertainties. We also aim to detail the errors that each input into the computation propagates to the final answer for each observable (3). In some cases, these uncertainties are large, and constitute a limitation to how sensitive experimental measurements can be in determining the underlying theory parameters. Finally, we discuss some implications for physics beyond the SM sensitivities in precision Higgs studies.
119474240
Model-independent properties of the B-meson distribution amplitude
The operator product expansion is used to obtain model-independent predictions for the first two moments of the renormalized $B$-meson light-cone distribution amplitude ${\ensuremath{\phi}}_{+}^{B}(\ensuremath{\omega},\ensuremath{\mu})$, defined with a cutoff $\ensuremath{\omega}\ensuremath{\le}{\ensuremath{\Lambda}}_{\mathrm{UV}}$. The leading hadronic power corrections are given in terms of the parameter $\overline{\ensuremath{\Lambda}}={m}_{B}\ensuremath{-}{m}_{b}$. From the cutoff dependence of the zeroth moment an analytical expression for the asymptotic behavior of the distribution amplitude is derived, which exhibits a negative radiation tail for $\ensuremath{\omega}\ensuremath{\gg}\ensuremath{\mu}$. By solving the evolution equation for the distribution amplitude, an integral representation for ${\ensuremath{\phi}}_{+}^{B}(\ensuremath{\omega},\ensuremath{\mu})$ is obtained in terms an initial function ${\ensuremath{\phi}}_{+}^{B}(\ensuremath{\omega},{\ensuremath{\mu}}_{0})$ defined at a lower renormalization scale. A realistic model of the $B$-meson light-cone distribution amplitude is proposed, which satisfies the moment relations and has the correct asymptotic behavior. This model provides an estimate for the first inverse moment and the associated parameter ${\ensuremath{\lambda}}_{B}$.
56381743
First experimental test of emittance measurement using the quadrupole-mode transfer function
We carried out the first experimental test of the emittance (thermal energy) measurement using the quadrupole-mode transfer function. We show that this method can be applied to measure the intrinsic thermal energy dynamical systems nondestructively. Since the QTF does not depend on the beam distribution, this method can be used to measure the rms emittance of different dynamical systems.
116306610
Drawbacks of Principal component analysis
One of the main tasks for present and future dark energy surveys is to determine whether the dark energy is dynamical or not. To illustrate this from data, it is commonly used to parameterize the dark energy equation of state w as several piecewise constant wis using the principal component analysis (PCA) method over finite redshift bins. We show that there is only $j-1$ free parameters wis if we choose the redshift as j bins. Without this constrain, one obtains the inconsistent results from the data analysis. Furthermore, if w decreases with non-negligible ratio as z does, then PCA fails to reproduce the original behavior of w. Also, time varying w can be confused with the incorrect value of constant one when the decreasing (or increasing) ratio of w is small but not negligible.
121911294
The RHIC design overview
The salient performance objectives for the Relativistic Heavy Ion Collider (RHIC) are presented and the rationale for the design choices of the major collider systems is conveyed. RHIC provides collisions of heavy ions covering the entire mass range from protons to gold. For the prototypical case of Au-on-Au, one obtains energies up to 100 GeV/n per beam and luminosities of B2 � 10 26 cm � 2 s � 1 , averaged over a 10-h storage time. Operation with polarized protons is also possible. The overall accelerator complex used for gold ions consists of the Tandem Van de Graaff, the Booster, the AGS, and the Collider itself, and the scenario for the beam transfer between machines is described. The two separate collider rings cross at six interaction points, where the lattice design provides low-beta insertions for maximum luminosity. The interaction diamond length of o20 cm rms is achieved by bunched beam operation and holding the 56 bunches in a 197 MHz radio-frequency (RF) system after their acceleration in a 28 MHz RF system. The rings are constructed with superconducting magnets, which have a cold bore aperture of 6.9 cm in the arcs. The RHIC specific design challenges posed by intrabeam scattering of heavy ions, passage through transition energy with slow-ramping superconducting magnets, and control of magnetic errors in the low-beta triplet quadrupoles are addressed. r 2002 Elsevier Science B.V. All rights reserved.
117717807
Spin flipping a stored vertically polarized proton beam with an RF solenoid
A recent experiment in the IUCF cooler ring studied the spin flip of a stored vertically polarized 139 MeV proton beam. This spin flip was accomplished by using an RF solenoid to induce an artificial depolarizing resonance in the ring, and then varying the solenoid’s frequency through this resonance value to induce spin flip. We found a polarization loss after multiple spin flips of about 0.00±0.05% per flip and also losses for very long flip times. This device will be useful for reducing systematic errors in polarized beam‐internal target scattering asymmetry experiments by enabling experimenters to perform frequent beam polarization reversals in the course of the experiment.
119287779
Color spin wave functions of heavy tetraquark states
Abstract Using the variational method, we calculate the mass of the J P = 1 + u d b ¯ b ¯ tetraquark containing two identical heavy antiquarks in a nonrelativistic potential model with color confinement and spin hyperfine interaction. In particular, we extend a previous investigation of the model by Brink and Stancu by investigating the effect of including the color anti-sextet component of the diquark configuration as well as using several more Gaussian parametrization for the L = 0 part of the spatial wave function. We find that for the heavy tetraquark, the 6 6 ¯ component among the color singlet bases is negligible and that the previously used specific Gaussian spatial configuration is good enough in obtaining the ground state energy.