arXiv subjects

M. Sigamani

Publications and source records attributed to M. Sigamani.

3 recordsLinked to original sources

arXiv2015

Observation of the rare $B^0_s\toμ^+μ^-$ decay from the combined analysis of CMS and LHCb data

A joint measurement is presented of the branching fractions $B^0_s\toμ^+μ^-$ and $B^0\toμ^+μ^-$ in proton-proton collisions at the LHC by the CMS and LHCb experiments. The data samples were collected in 2011 at a centre-of-mass energy of 7 TeV, and in 2012 at 8 TeV. The combined analysis produces the first observation of the $B^0_s\toμ^+μ^-$ decay, with a statistical significance exceeding six standard deviations, and the best measurement of its branching fraction so far. Furthermore, evidence for the $B^0\toμ^+μ^-$ decay is obtained with a statistical significance of three standard deviations. The branching fraction measurements are statistically compatible with SM predictions and impose stringent constraints on several theories beyond the SM.

hep-ex↗

arXiv2011

Measurements of the Partial Branching Fraction for B->Xulnu and the Determination of Vub

We measure partial branching fractions for the inclusive charmless semileptonic decay of $\Bxulnu$, and present determinations of the CKM matrix element $\Vub$. This analysis is based on a sample of 467 million $\FourS$ decays into $\BB$ pairs, collected with the \babar\ detector at the PEP-II $e^{+} e^{-}$ storage rings. We select events where one of the B mesons is fully reconstructed in a hadronic decay mode and the other B decays semileptonically into an electron or a muon. We then use the invariant mass, $\mx$, of the hadronic system, the invariant mass squared, $q^{2}$, of the lepton and neutrino pair, the lepton momentum in the in the $B$ meson rest frame $\Pl$, the kinematic variable $P_{+}$ or one of their combinations as discriminating variables to isolate $\Bxulnu$ decays from the background. We then measure the partial branching fractions in various regions of phase space These partial branching fractions are translated into values of $\Vub$ using several theoretical calculations. An estimate based on the most inclusive analysis gives $\Vub = (4.31\pm 0.35) \times 10^{-3}$. Furthermore, we place a limit on isospin breaking in $B\to X_u\ellν$ decays of 9% at 90% C.L. using separate measurements of partial branching ratios for $B^0$ and $B^+$.

hep-ex↗

arXiv2011

Semileptonic B-Meson Decays at BaBar

Presented are selected results of semileptonic B decays at BaBar. Two measurements of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ are reported. One using moments of the hadronic-mass spectrum in inclusive $\bar{B} \to X_{c} \ell^{-} \barν$ decays, and the other, exclusive $\bar{B} \to D \ell^- \barν_{\ell}$ decays. These results are based on data samples of 232 (inclusive $\bar{B} \to X_{c} \ell^{-} \barν$) and 460 (exclusive $\var{B} \to D \ell^- \barν_{\ell}$) million $Υ(4S) \to B\bar{B}$ decays, recorded by the $BaBar$ detector at the PEP-II $e^+e^-$-storage rings. Semileptonic B decays are identified by requiring a lepton ($e$ or $μ$) in events tagged with a full reconstruction of one of the B mesons in the $B\bar{B}$ pair.

hep-ex↗