1,268 research outputs found
"Pair production of scalar top quarks in e+e- collisions at ILC."
We study the pair production of scalar top quarks in e+e- collisions with the
subsequent decay of the top squarks into b-quarks and charginos. We simulate
this process using PYTHIA6.4 for beam energies 2E_beam = 350, 400, 500, 800,
1000 GeV. Proposing a set of criteria we obtain a good separation of the signal
stop events from top quark pair production which is the main background. The
number of stop production events obtained with the proposed cuts for different
energies is calculated for an integrated luminosity of 1000 1/fb. We propose a
method to reconstruct the mass of the top squark, provided the mass of the
lightest neutralino is known, and estimate the error of the mass determination
for the case sqrt{s} = 500 GeV.Comment: 25 pages, 27 figures, ILC-NOTE-2008-042. v1 was presented by the 4-th
author and published in the Proceedings of the 15-th International Seminar on
High Energy Physics QUARKS-2008 (Institute for Nuclear Research of RAS,
Sergiev Posad, Russia, 23-29 May 2008), V1, p.227-246, ISBN
978-5-94274-123-5. v2 - another set of cuts was chosen. v3 - some typos
correcte
Light Higgsino Detection at LEP1.5
Within the minimal supersymmetric extension of the Standard Model, the best
fit to the most recent precision-measurement data requires charginos and
neutralinos, with dominant Higgsino components and with masses within the reach
of LEP1.5 ( GeV). In this work, we present a detailed analysis of
the neutralino and chargino production processes for the favoured region of
parameter space, that is low values of and either low or large values
of . We find that chargino and neutralino searches can cover the
Higgsino region in the () plane for values of M_2 \simlt 1 TeV, at
the next phases of the LEP collider. We also show that, due mainly to
phase-space constraints, the lightest neutralinos should be more easily
detectable than charginos in most of the parameter space preferred by
precision-measurement data.Comment: 16 pages, 8 Figures, LateX. Figures now include initial state
radiation effects on the cross sections
Proton-Pump inhibitors related acute interstitial nephritis. A case report
Background: Acute Interstitial nephritis is a common and reversible cause of Acute Kidney Injury, accounting for 15-27% of renal biopsies performed because of this condition. Its incidence has been increasing worldwide. By and large, drug-induced AIN is currently the most common etiology, with antimicrobials and nonsteroidal anti-inflammatory drugs being the most frequent offending agents. The hallmark pathologic features are interstitial edema, interstitial inflammation, and tubulitis with a predominance of CD4+ T lymphocytes and mononuclear cells, with variable numbers of eosinophils. Patients with AIN typically present with nonspecific symptoms of acute renal failure, including oliguria, malaise, anorexia, nausea, and vomiting and a high-suspicious index is necessary. A case is described of a 29-year-old Hispanic obese and diabetic female, who developed AIN after an average period of 2 years of omeprazole. The symptoms were mostly fatigue and anorexia. She had non-nephrotic range proteinuria with pyuria with a mean serum creatinine of 4.72 mg/dl. Eosinophils in urine were normal. Patient also tested positive for ANA, and initially lupus nephritis was in the differentials along with Focal segemental glomerulo-sclerosis due to obestiry. Renal biopsy showed severe interstitial inflammation with lymphoid cells, scattered neutrophils, and very rate eosinophils, ruling out FSGS and lupus nephritis. Omeprazole was discontinued, and Prednisone 60 mg daily were started. Renal recovery was total in 6 weeks post-steroid therapy. Steroids were tapered as the kidney function improved.
Conclusion: Prompt recognition, elimination of the offending source of antigen and use of a limited course of steroid therapy are the mainstay of the treatment. This will result in complete resolution in ~ 65% of cases, partial resolution in up to 20%, and irreversible damage in the rest. Recent studies strongly suggest that early steroid administration (within 7 days after diagnosis) improves the recovery of renal function, decreasing the risk of chronic renal impairment
Flavour violating bosonic squark decays at LHC
We study quark flavour violation (QFV) in the squark sector of the Minimal
Supersymmetric Standard Model (MSSM). We assume mixing between the second and
the third squark generations, i.e. sc_R-st_{L,R} mixing mixing. We focus on QFV
effects in bosonic squark decays, in particular on the decay into the lightest
Higgs boson h0, su_2 -> su_1 h0, where su_{1,2} are the lightest up-type
squarks. We show that the branching ratio of this QFV decay can be quite large
(up to 50 %) due to large QFV trilinear couplings, and large sc_R-st_{L, R} and
st_L-st_R mixing, despite the strong constraints on QFV from B meson data. This
can result in characteristic QFV final states with significant rates at LHC (14
TeV), such as pp -> gluino gluino X -> t + h0 + 3jets + Etmiss + X and pp ->
gluino gluino X -> t t (or tbar tbar) + h0 + 2jets + Etmiss + X. The QFV
bosonic squark decays can have an influence on the squark and gluino searches
at LHC.Comment: Figure 3 replaced, Section 4 revise
Flavour violating squark and gluino decays at LHC
We study the effects of squark generation mixing on squark and gluino
production and decays at LHC in the Minimal Supersymmetric Standard Model
(MSSM) with focus on the mixing between second and third generation squarks.
Taking into account the constraints from B-physics experiments we show that
various regions in parameter space exist where decays of squarks and/or gluinos
into quark flavour violating (QFV) final states can have large branching
ratios. Here we consider both fermionic and bosonic decays of squarks. Rates of
the corresponding QFV signals, e.g. pp -> t t bar{c} bar{c} missing-E_T X, can
be significant at LHC(14 TeV). We find that the inclusion of flavour mixing
effects can be important for the search of squarks and gluinos and the
determination of the underlying model parameters of the MSSM at LHC.Comment: 7 pages, 4 figures, a reference updated, Proceedings of The 36th
International Conference on High Energy Physics (ICHEP2012), Melbourne,
Australia, July 4-11, 201
CP asymmetries in the supersymmetric trilepton signal at the LHC
In the CP-violating Minimal Supersymmetric Standard Model, we study the
production of a neutralino-chargino pair at the LHC. For their decays into
three leptons, we analyze CP asymmetries which are sensitive to the CP phases
of the neutralino and chargino sector. We present analytical formulas for the
entire production and decay process, and identify the CP-violating
contributions in the spin correlation terms. This allows us to define the
optimal CP asymmetries. We present a detailed numerical analysis of the cross
sections, branching ratios, and the CP observables. For light neutralinos,
charginos, and squarks, the asymmetries can reach several 10%. We estimate the
discovery potential for the LHC to observe CP violation in the trilepton
channel.Comment: 39 pages, 8 figures, version to appear in EPJC, discussion(s) added,
typo in (D.79), (D.118) corrected, new Fig. 7; The European Physical Journal
C, Volume 72, Issue 3, 201
Supersymmetric Electroweak Corrections to Heavier Top Squark Decay into Lighter Top Squark and Neutral Higgs Boson
We calculate the Yukawa corrections of order , and
to the widths of the decays in the Minimal Supersymmetric Standard
Model, and perform a detailed numerical analysis. We also compare the results
with the ones presented in an earlier literature, where the SUSY-QCD corrections to the same three decay processes have
been calculated.
Our numerical results show that for the decays , , the Yukawa corrections are
significant in most of the parameter range, which can reach a few ten percent,
and for the decay , the Yukawa corrections are
relatively smaller, which are only a few percent. The numerical calculations
also show that using the running quark masses and the running trilinear
coupling , which include the QCD, SUSY-QCD, SUSY-Electroweak effects and
resume all high order ()-enhanced effects, can vastly improve the
convergence of the perturbation expansion. We also discuss the effects of the
running of the higgsino mass parameter on the corrections, and find that
they are significant, too, especially for large .Comment: 37 pages, 19 eps figure
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.
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