92 research outputs found
Electron Electric Dipole Moment from Lepton Flavor Violation
The general Minimal Supersymmetric Standard Model introduces new sources for
Lepton Flavor Violation (LFV) as well as CP-violation. In this paper, we show
that when both sources are present, the electric dipole moment of the electron,
, receives a contribution from the phase of the trilinear -term of
staus, . For , the value of ,
depending on the ratios of the LFV mass elements, can range between zero and
three orders of magnitude above the present bound. We show that the present
bound on rules out a large portion of the CP-violating and the LFV
parameter space which is consistent with the bounds on the LFV rare decays.
We show that studying the correlation between and the P-odd asymmetry
in helps us to derive a more conclusive bound on
We also discuss the possibility of cancelation among the contributions of
different CP-violating phases to .Comment: 35 pages, 9 figure
Can Measurements of Electric Dipole Moments Determine the Seesaw Parameters?
In the context of the supersymmetrized seesaw mechanism embedded in the
Minimal Supersymmetric Standard Model (MSSM), complex neutrino Yukawa couplings
can induce Electric Dipole Moments (EDMs) for the charged leptons, providing an
additional route to seesaw parameters. However, the complex neutrino Yukawa
matrix is not the only possible source of CP violation. Even in the framework
of Constrained MSSM (CMSSM), there are additional sources, usually attributed
to the phases of the trilinear soft supersymmetry breaking couplings and the
mu-term, which contribute not only to the electron EDM but also to the EDMs of
neutron and heavy nuclei. In this work, by combining bounds on various EDMs, we
analyze how the sources of CP violation can be discriminated by the present and
planned EDM experiments.Comment: 26 pages, 9 figures; added reference
Reconstructing the two right-handed neutrino model
In this paper we propose a low-energy parametrization of the two right-handed
neutrino model, and discuss the prospects to determine experimentally these
parameters in supersymmetric scenarios. In addition, we present exact formulas
to reconstruct the high-energy leptonic superpotential in terms of the
low-energy observables. We also discuss limits of the three right-handed
neutrino model where this procedure applies.Comment: 28 pages, 4 figures. Typos corrected, references adde
Weak Isospin Violations in Charged and Neutral Higgs Couplings from SUSY Loop Corrections
Supersymmetric QCD and supersymmetric electroweak loop corrections to the
violations of weak isospin to Yukawa couplings are investigated. Specifically
it involves an analysis of the supersymmetric loop corrections to the Higgs
couplings to the third generation quarks and leptons. Here we analyze the SUSY
loop corrections to the charged Higgs couplings which are then compared with
the supersymmetric loop corrections to the neutral Higgs couplings previously
computed. It is found that the weak isospin violations can be quite
significant, i.e, as much as 40-50% or more of the total loop correction to the
Yukawa coupling. The effects of CP phases are also studied and it is found that
these effects can either enhance or suppress the weak isospin violations. We
also investigate the weak isospin violation effects on the branching ratio
and show that the effects
are sensitive to CP phases. Thus an accurate measurement of this branching
ratio along with the branching ratio of the neutral Higgs boson decays can
provide a measure of weak isospin violation along with providing a clue to the
presence of supersymmetry.Comment: 20 pages, 9 figure
Effects of Large CP violating phases on g_{\m}-2 in MSSM
Effects of CP violation on the supersymmetric electro-weak correction to the
anomalous magnetic moment of the muon are investigated with the most general
allowed set of CP violating phases in MSSM. The analysis includes contributions
from the chargino and the neutralino exchanges to the muon anomaly. The
supersymmetric contributions depend only on specific combinations of CP phases.
The independent set of such phases is classified. We analyse the effects of the
phases under the EDM constraints and show that large CP violating phases can
drastically affect the magnitude of the supersymmetric electro-weak
contribution to and may even affect its overall sign.Comment: 26 pages Latex file including 4 figure
Large-area (> 50 cm × 50 cm), freestanding, flexible, optical membranes of Cd-free nanocrystal quantum dots
Colloidal semiconductor quantum dots (QDs) have been extensively explored for numerous applications ranging from optoelectronics to biotechnology. This strong demand for the colloidal QDs arises because of their favorable optical and electronic properties. From the application points of view, QDs typically need to be used in their solid form, as opposed to their as-synthesized dispersion form. For immobilization of QDs and homogeneity of their films, various polymers have been used to host QDs within solid media. However, the integration of QDs into a polymeric medium is commonly complex, which requires a high level of understanding to provide optical quality. © 2012 IEEE
Top Squarks and Bottom Squarks in the MSSM with Complex Parameters
We present a phenomenological study of top squarks (~t_1,2) and bottom
squarks (~b_1,2) in the Minimal Supersymmetric Standard Model (MSSM) with
complex parameters A_t, A_b, \mu and M_1. In particular we focus on the CP
phase dependence of the branching ratios of (~t_1,2) and (~b_1,2) decays. We
give the formulae of the two-body decay widths and present numerical results.
We find that the effect of the phases on the (~t_1,2) and (~b_1,2) decays can
be quite significant in a large region of the MSSM parameter space. This could
have important implications for (~t_1,2) and (~b_1,2) searches and the MSSM
parameter determination in future collider experiments. We have also estimated
the accuracy expected in the determination of the parameters of ~t_i and ~b_i
by a global fit of the measured masses, decay branching ratios and production
cross sections at e^+ e^- linear colliders with polarized beams. Analysing two
scenarios, we find that the fundamental parameters apart from A_t and A_b can
be determined with errors of 1% to 2%, assuming an integrated luminosity of 1
ab^-1 and a sufficiently large c.m.s. energy to produce also the heavier ~t_2
and ~b_2 states. The parameter A_t can be determined with an error of 2 - 3%,
whereas the error on A_b is likely to be of the order of 50%.Comment: 31 pages, 8 figures, comments and references added, conclusions
unchanged; version to appear in Phys. Rev.
COVID-19 and stem cell transplantation; results from an EBMT and GETH multicenter prospective survey
Altres ajuts: British Society for Blood and Marrow Transplantation and Cellular Therapy (BSBMTCT); UK NIHR Imperial College Biomedical Research Centre.This study reports on 382 COVID-19 patients having undergone allogeneic (n = 236) or autologous (n = 146) hematopoietic cell transplantation (HCT) reported to the European Society for Blood and Marrow Transplantation (EBMT) or to the Spanish Group of Hematopoietic Stem Cell Transplantation (GETH). The median age was 54.1 years (1.0-80.3) for allogeneic, and 60.6 years (7.7-81.6) for autologous HCT patients. The median time from HCT to COVID-19 was 15.8 months (0.2-292.7) in allogeneic and 24.6 months (−0.9 to 350.3) in autologous recipients. 83.5% developed lower respiratory tract disease and 22.5% were admitted to an ICU. Overall survival at 6 weeks from diagnosis was 77.9% and 72.1% in allogeneic and autologous recipients, respectively. Children had a survival of 93.4%. In multivariate analysis, older age (p = 0.02), need for ICU (p < 0.0001) and moderate/high immunodeficiency index (p = 0.04) increased the risk while better performance status (p = 0.001) decreased the risk for mortality. Other factors such as underlying diagnosis, time from HCT, GVHD, or ongoing immunosuppression did not significantly impact overall survival. We conclude that HCT patients are at high risk of developing LRTD, require admission to ICU, and have increased mortality in COVID-19
Probing exotic phenomena at the interface of nuclear and particle physics with the electric dipole moments of diamagnetic atoms: A unique window to hadronic and semi-leptonic CP violation
The current status of electric dipole moments of diamagnetic atoms which
involves the synergy between atomic experiments and three different theoretical
areas -- particle, nuclear and atomic is reviewed. Various models of particle
physics that predict CP violation, which is necessary for the existence of such
electric dipole moments, are presented. These include the standard model of
particle physics and various extensions of it. Effective hadron level combined
charge conjugation (C) and parity (P) symmetry violating interactions are
derived taking into consideration different ways in which a nucleon interacts
with other nucleons as well as with electrons. Nuclear structure calculations
of the CP-odd nuclear Schiff moment are discussed using the shell model and
other theoretical approaches. Results of the calculations of atomic electric
dipole moments due to the interaction of the nuclear Schiff moment with the
electrons and the P and time-reversal (T) symmetry violating
tensor-pseudotensor electron-nucleus are elucidated using different
relativistic many-body theories. The principles of the measurement of the
electric dipole moments of diamagnetic atoms are outlined. Upper limits for the
nuclear Schiff moment and tensor-pseudotensor coupling constant are obtained
combining the results of atomic experiments and relativistic many-body
theories. The coefficients for the different sources of CP violation have been
estimated at the elementary particle level for all the diamagnetic atoms of
current experimental interest and their implications for physics beyond the
standard model is discussed. Possible improvements of the current results of
the measurements as well as quantum chromodynamics, nuclear and atomic
calculations are suggested.Comment: 46 pages, 19 tables and 16 figures. A review article accepted for
EPJ
Observation of a new Xi(b) baryon
The first observation of a new b baryon via its strong decay into Xi(b)^-
pi^+ (plus charge conjugates) is reported. The measurement uses a data sample
of pp collisions at sqrt(s) = 7 TeV collected by the CMS experiment at the LHC,
corresponding to an integrated luminosity of 5.3 inverse femtobarns. The known
Xi(b)^- baryon is reconstructed via the decay chain Xi(b)^- to J/psi Xi^- to
mu^+ mu^- Lambda^0 pi^-, with Lambda^0 to p pi^-. A peak is observed in the
distribution of the difference between the mass of the Xi(b)^- pi^+ system and
the sum of the masses of the Xi(b)^- and pi^+, with a significance exceeding
five standard deviations. The mass difference of the peak is 14.84 +/- 0.74
(stat.) +/- 0.28 (syst.) MeV. The new state most likely corresponds to the
J^P=3/2^+ companion of the Xi(b).Comment: Submitted to Physical Review Letter
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