319 research outputs found
Using Tau Polarization for Charged Higgs Boson and SUSY Searches at LHC
The polarization can be easily measured at LHC in the 1-prong hadronic
decay channel by measuring what fraction of the -jet momentum is
carried by the charged track. A simple cut requiring this fraction to be >0.8
retains most of the polarization of +1 -jet signal while
suppressing the polarization of -1 -jet background and practically
eliminating the fake background. This can be utilized to extract the
charged Higgs signal. It can be also utilized to extract the SUSY signal in the
stau NLSP region, and in particular the stau co-annihilaton region.Comment: 8 pages, 9 figures; Fig.8 and Fig.9 are replaced, published in
"Physics at the Large Hadron Collider", A Platinum Jubilee Special Issue of
the Indian National Science Academy, Springer (2009) p 20
CP Violation in EPR-like neutrino oscillations
After reviewing the general framework to study EPR-like neutrino
oscillations, we derive expressions for the oscillation probabilities and a
direct measure of CP violation. We compare the possibility of studying CP
violation in this case with that of baseline accelerator experiments and
conclude that it is possible to study CP violation in experiments with length
scales comparable to that of short baseline accelerator experiments.Comment: 5 pages, latex, revtex style, no figures, more discussions are added
in the revised versio
A note on accelerating cosmologies from compactifications and S-branes
We give a simple interpretation of the recent solutions for cosmologies with
a transient accelerating phase obtained from compactification in hyperbolic
manifolds, or from S-brane solutions of string/M-theory. In the
four-dimensional picture, these solutions correspond to bouncing the radion
field off its exponential potential. Acceleration occurs at the turning point,
when the radion stops and the potential energy momentarily dominates. The
virtues and limitations of these approaches become quite transparent in this
interpretation.Comment: 9 pages, 1 figure. References adde
Evaluation of Dynamic Models of Distillation Columns with Emphasis on the Initial Response
The flow dynamics (tray hydraulics) are of key importance for the initial dynamic response of distillation columns. The most important parameters are the liquid holdup, the liquid hydraulic time constant and the vapor constant representing the initial effect of a change in vapor flow on liquid flow. In the paper we present methods for determining these parameters experimentally, and compare the results with estimates from available correlations such as the Francis Weir formula
Thermopower of the Correlated Narrow Gap Semiconductor FeSi and Comparison to RuSi
Iron based narrow gap semiconductors such as FeSi, FeSb2, or FeGa3 have
received a lot of attention because they exhibit a large thermopower, as well
as striking similarities to heavy fermion Kondo insulators. Many proposals have
been advanced, however, lacking quantitative methodologies applied to this
problem, a consensus remained elusive to date. Here, we employ realistic
many-body calculations to elucidate the impact of electronic correlation
effects on FeSi. Our methodology accounts for all substantial anomalies
observed in FeSi: the metallization, the lack of conservation of spectral
weight in optical spectroscopy, and the Curie susceptibility. In particular we
find a very good agreement for the anomalous thermoelectric power. Validated by
this congruence with experiment, we further discuss a new physical picture of
the microscopic nature of the insulator-to-metal crossover. Indeed, we find the
suppression of the Seebeck coefficient to be driven by correlation induced
incoherence. Finally, we compare FeSi to its iso-structural and iso-electronic
homologue RuSi, and predict that partially substituted Fe(1-x)Ru(x)Si will
exhibit an increased thermopower at intermediate temperatures.Comment: 14 pages. Proceedings of the Hvar 2011 Workshop on 'New materials for
thermoelectric applications: theory and experiment
Resistivity Anisotropy of FeAs ( =Ca, Sr, Ba): direct versus Montgomery technique measurements
The anisotropy of electrical resistivity was measured in parent compounds of
the iron-arsenic high temperature superconductors, AEFe2As2 with Alkali Earth
elements AE=Ca,Sr, Ba. Measurements were performed using both the Montgomery
technique and direct resistivity measurements on samples cut along principal
crystallographic directions. The anisotropy ratio \gamma_\rho=\rho_c/\rho_a is
well below 10 for all compounds in the whole temperature range studied (4 to
300 K), in notable contrast to previous reports. The anisotropy at room
temperature increases from about 2 in Ca, to about 4 in Sr and Ba. In all
compounds the resistivity ratio decreases on cooling through the
structural/antiferromagnetic transition temperature T_{SM}, with the change
mainly coming from stronger variation in \rho_a as compared with \rho_c. This
suggests that the transitions stronger affect the two-dimensional parts of the
Fermi surface. We compare our experimental observations with band structure
calculations, and find similar trend in the evolution of anisotropy with the
size of AE ion. Our results show that the electronic structure of the iron
pnictides has large contribution from three-dimensional areas of the Fermi
surface
Inflating in a Better Racetrack
We present a new version of our racetrack inflation scenario which, unlike
our original proposal, is based on an explicit compactification of type IIB
string theory: the Calabi-Yau manifold P^4_[1,1,1,6,9]. The axion-dilaton and
all complex structure moduli are stabilized by fluxes. The remaining 2 Kahler
moduli are stabilized by a nonperturbative superpotential, which has been
explicitly computed. For this model we identify situations for which a linear
combination of the axionic parts of the two Kahler moduli acts as an inflaton.
As in our previous scenario, inflation begins at a saddle point of the scalar
potential and proceeds as an eternal topological inflation. For a certain range
of inflationary parameters, we obtain the COBE-normalized spectrum of metric
perturbations and an inflationary scale of M = 3 x 10^{14} GeV. We discuss
possible changes of parameters of our model and argue that anthropic
considerations favor those parameters that lead to a nearly flat spectrum of
inflationary perturbations, which in our case is characterized by the spectral
index n_s = 0.95.Comment: 20 pages, 7 figures. Brief discussion on the non-gaussianity of this
model, one more figure of the field trajectories added as well as other minor
changes to the tex
A Priori Mixed Hadrons, Weak Radiative and Non-leptonic Decays of Hyperons
A priori mixings of eigenstates in physical states are quantum mechanical
effects well known in several realms of physics. The possibility that such
effects are also present in particle physics, in the form of flavor and parity
mixings, is studied. Applications to weak radiative and non-leptonic decays of
hyperons are discussed
Search for flavor lepton number violation in slepton decays at LEP2 and NLC
We show that in supersymmetric models with explicit flavor lepton number
violation due to soft supersymmetry breaking terms there must be flavor lepton
number violation in slepton decays. We propose to look for flavor lepton number
violation in righthanded selectron and smuon decays. For selectron and smuon
lighter than 80 Gev flavor lepton number violation in slepton decays could be
discovered at LEP2 provided the mixing betwen selectron and smuon is not small.
We also estimate NLC discovery potential of the lepton flavor number violation
in slepton decays.Comment: 12 pages, latex, no figure
Cardiovascular end points and mortality are not closer associated with central than peripheral pulsatile blood pressure components
none32Pulsatile blood pressure (BP) confers cardiovascular risk. Whether associations of cardiovascular end points are tighter for central systolic BP (cSBP) than peripheral systolic BP (pSBP) or central pulse pressure (cPP) than peripheral pulse pressure (pPP) is uncertain. Among 5608 participants (54.1% women; mean age, 54.2 years) enrolled in nine studies, median follow-up was 4.1 years. cSBP and cPP, estimated tonometrically from the radial waveform, averaged 123.7 and 42.5 mm Hg, and pSBP and pPP 134.1 and 53.9 mm Hg. The primary composite cardiovascular end point occurred in 255 participants (4.5%). Across fourths of the cPP distribution, rates increased exponentially (4.1, 5.0, 7.3, and 22.0 per 1000 person-years) with comparable estimates for cSBP, pSBP, and pPP. The multivariable-adjusted hazard ratios, expressing the risk per 1-SD increment in BP, were 1.50 (95% CI, 1.33-1.70) for cSBP, 1.36 (95% CI, 1.19-1.54) for cPP, 1.49 (95% CI, 1.33-1.67) for pSBP, and 1.34 (95% CI, 1.19-1.51) for pPP (P<0.001). Further adjustment of cSBP and cPP, respectively, for pSBP and pPP, and vice versa, removed the significance of all hazard ratios. Adding cSBP, cPP, pSBP, pPP to a base model including covariables increased the model fit (P<0.001) with generalized R2 increments ranging from 0.37% to 0.74% but adding a second BP to a model including already one did not. Analyses of the secondary end points, including total mortality (204 deaths), coronary end points (109) and strokes (89), and various sensitivity analyses produced consistent results. In conclusion, associations of the primary and secondary end points with SBP and pulse pressure were not stronger if BP was measured centrally compared with peripherally.noneHuang, Qi-Fang; Aparicio, Lucas S; Thijs, Lutgarde; Wei, Fang-Fei; Melgarejo, Jesus D; Cheng, Yi-Bang; Sheng, Chang-Sheng; Yang, Wen-Yi; Gilis-Malinowska, Natasza; Boggia, José; Niiranen, Teemu J; Wojciechowska, Wiktoria; Stolarz-Skrzypek, Katarzyna; Barochiner, Jessica; Ackermann, Daniel; Tikhonoff, Valérie; Ponte, Belen; Pruijm, Menno; Casiglia, Edoardo; Narkiewicz, Krzysztof; Filipovský, Jan; Czarnecka, Danuta; Kawecka-Jaszcz, Kalina; Jula, Antti M; Bochud, Murielle; Vanassche, Thomas; Verhamme, Peter; Struijker-Boudier, Harry A J; Wang, Ji-Guang; Zhang, Zhen-Yu; Li, Yan; Staessen, Jan AHuang, Qi-Fang; Aparicio, Lucas S; Thijs, Lutgarde; Wei, Fang-Fei; Melgarejo, Jesus D; Cheng, Yi-Bang; Sheng, Chang-Sheng; Yang, Wen-Yi; Gilis-Malinowska, Natasza; Boggia, José; Niiranen, Teemu J; Wojciechowska, Wiktoria; Stolarz-Skrzypek, Katarzyna; Barochiner, Jessica; Ackermann, Daniel; Tikhonoff, Valérie; Ponte, Belen; Pruijm, Menno; Casiglia, Edoardo; Narkiewicz, Krzysztof; Filipovský, Jan; Czarnecka, Danuta; Kawecka-Jaszcz, Kalina; Jula, Antti M; Bochud, Murielle; Vanassche, Thomas; Verhamme, Peter; Struijker-Boudier, Harry A J; Wang, Ji-Guang; Zhang, Zhen-Yu; Li, Yan; Staessen, Jan
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