49 research outputs found
Search for Heavy Neutrino in K->mu nu_h(nu_h-> nu gamma) Decay at ISTRA+ Setup
Heavy neutrino nu_h with m_h < 300MeV/c^2 can be effectively searched for in
kaon decays. We put upper limits on mixing matrix element |U_mu_h}|^2 for
radiatively decaying nu_h from K->mu nu_h (nu_h -> nu gamma) decay chain in the
following parameter region: 30MeV/c^2 < m_h < 80MeV/c^2; 10^{-11}sec < tau_h <
10^{-9}sec. For the whole region |U_{mu h}|^2 < 5 x 10^{-5} for Majorana type
of nu_h and | U_{\mu h}|^2 < 8 x 10^{-5} for the Dirac case.Comment: Published in Phys. Lett.
Extraction of Kaon Formfactors from K^- -> mu^- nu_mu gamma Decay at ISTRA+ Setup
The radiative decay K->mu nu gamma has been studied at ISTRA+ setup in a new
kinematical region. About 22K events of K^- -> mu^- nu_mu gamma have been
observed. The sign and value of Fv-Fa have been measured for the first time.
The result is Fv-Fa=0.21(4)(4).Comment: 11 pages, 21 figures, submitted to Phys. Lett.
Search for light pseudoscalar sgoldstino in K- decays
A search for the light pseudoscalar sgoldstino production in the three body
K- decay K-->pipi0P has been performed with the ISTRA+ detector exposed to the
25 GeV negative secondary beam of the U70 proton synchrotron. No signal is
seen. An upper limit for the branching ratio Br(K->pipi0P), at 90% confidence
level, is found to be around 9*10**-6 in the effective mass m(P) range from 0
till 200 MeV, excluding the region near m(pi0) where it degrades to 3.5*10**-5.Comment: 10 pages, LATEX, 8 EPS figures, revised version, to be published in
Phys.Lett.
High statistic measurement of the K- -> pi0 e- nu decay form-factors
The decay K- -> pi0 e- nu is studied using in-flight decays detected with the
ISTRA+ spectrometer. About 920K events are collected for the analysis. The
lambda+ slope parameter of the decay form-factor f+(t) in the linear
approximation (average slope) is measured: lambda+(lin)= 0.02774 +-
0.00047(stat) +- 0.00032(syst). The quadratic contribution to the form-factor
was estimated to be lambda'+ = 0.00084 +- 0.00027(stat) +- 0.00031(syst). The
linear slope, which has a meaning of df+(t)/dt|_{t=0} for this fit, is lambda+
= 0.02324 +- 0.00152(stat) +- 0.00032(syst). The limits on possible tensor and
scalar couplings are derived: f_{T}/f_{+}(0)=-0.012 +- 0.021(stat) +-
0.011$(syst), f_{S}/f_{+}(0)=-0.0037^{+0.0066}_{-0.0056}(stat) +- 0.0041(syst).Comment: 11 pages, 8 figures. Accepted by Phys.Lett.
Measurement of the Dalitz plot slope parameters for K- -> pi0 pi0 pi- decay using ISTRA+ detector
The Dalitz plot slope parameters g, h and k for the K- -> pi0 pi0 pi- decay
have been measured using in-flight decays detected with the ISTRA+ setup
operating in the 25 GeV negative secondary beam of the U-70 PS. About 252 K
events with four-momenta measured for the pi- and four involved photons were
used for the analysis. The values obtained g=0.627+/-0.004(stat)+/-0.010(syst),
h=0.046+/-0.004(stat)+/-0.012(syst), k=0.001+/-0.001(stat)+/-0.002(syst) are
consistent with the world averages dominated by K+ data, but have significantly
smaller errors.Comment: LaTeX, 10 pages, 8 eps-figures, update of IHEP 2002-1
High statistics study of the K- -> pi0 e- nu decay
The decay K- -> pi0 e- nu has been studied using in-flight decays detected
with the "ISTRA+" spectrometer working at the 25 GeV negative secondary beam of
the U-70 PS. About 550K events were used for the analysis. The lambda+
parameter of the vector form-factor has been measured: lambda+ = 0.0286 +-
0.0008 (stat) +- 0.0006(syst). The limits on the possible tensor and scalar
couplings have been obtained: f(T)/f+(0)=0.021 +0.064 -0.075 (stat) +-
0.026(syst) ; f(S)/f+(0)=0.002 +0.020 -0.022 (stat) +- 0.003(syst)Comment: LaTeX-2e, epsfig.sty, 10 pages, 7 figures in EPS forma
High statistic study of the K- -> pi0 mu- nu decay
The decay K- -> pi0 mu- nu has been studied using in-flight decays detected
with the "ISTRA+" spectrometer. About 540K events were collected for the
analysis. The lambda+ and lambda0 slope parameters of the decay form-factors
f+(t), f0(t) have been measured : lambda+ = 0.0277+-0.0013 (stat)+-0.0009
(syst), lambda0 = 0.0183+-0.0011(stat)+-0.0006(syst), and
d(lambda0)/d(lambda+)=-0.348. The limits on the possible tensor and scalar
couplings have been derived: fT/f+(0)=-0.0007 +- 0.0071, fS/f+(0)=0.0017 +-
0.0014. No visible non-linearity in the form-factors have been observed.Comment: 11 pages, 8 EPS figures, accepted by Physics Letters
Measurement of K^0_e3 form factors
The semileptonic decay of the neutral K meson, KL -> pi e nu (Ke3), was used
to study the strangeness-changing weak interaction of hadrons. A sample of 5.6
million reconstructed events recorded by the NA48 experiment was used to
measure the Dalitz plot density. Admitting all possible Lorentz-covariant
couplings, the form factors for vector (f_+(q^2)), scalar (f_S) and tensor
(f_T) interactions were measured. The linear slope of the vector form factor
lambda_+ = 0.0284+-0.0007+-0.0013 and values for the ratios |f_S/f_+(0)| =
0.015^{+0.007}_{-0.010}+-0.012 and |f_T/f_+(0)| = 0.05^{+0.03}_{-0.04}+-0.03
were obtained. The values for f_S and f_T are consistent with zero. Assuming
only Vector-Axial vector couplings, lambda_+ = 0.0288+-0.0004+-0.0011 and a
good fit consistent with pure V-A couplings were obtained. Alternatively, a fit
to a dipole form factor yields a pole mass of M = 859+-18 MeV, consistent with
the K^*(892) mass.Comment: 16 pages, 7 figures. submitted to Phys. Lett.
The supersymmetric prediction for the muon transverse polarization in the decay
The muon transverse polarization in the
decay will be measured at the level in forthcoming experiments. We
compare the phenomenological perspectives with the theoretical predictions in
supersymmetric extensions of the standard model. In the minimal extension,
CP-violating phases lead to a non-zero transverse polarization, that however is
too small to account for a positive experimental signal. The problems that one
encounters when departing from minimal assumptions are discussed. An observable
effect is possible if the hypothesis of R-parity conservation is relaxed, but
only at the price of assuming a very special pattern for the R-parity breaking
couplings.Comment: latex, 18 pages, 1 latex figur
Alignment of the CMS silicon tracker during commissioning with cosmic rays
This is the Pre-print version of the Article. The official published version of the Paper can be accessed from the link below - Copyright @ 2010 IOPThe CMS silicon tracker, consisting of 1440 silicon pixel and 15 148 silicon strip detector modules, has been aligned using more than three million cosmic ray charged particles, with additional information from optical surveys. The positions of the modules were determined with respect to cosmic ray trajectories to an average precision of 3–4 microns RMS in the barrel and 3–14 microns RMS in the endcap in the most sensitive coordinate. The results have been validated by several studies, including laser beam cross-checks, track fit self-consistency, track residuals in overlapping module regions, and track parameter resolution, and are compared with predictions obtained from simulation. Correlated systematic effects have been investigated. The track parameter resolutions obtained with this alignment are close to the design performance.This work is supported by FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ,
and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS
(Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia);
Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG,
and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF (Korea); LAS (Lithuania); CINVESTAV, CONACYT,
SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTDS (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA)