3,039 research outputs found
Quarkonia production and polarization at the hadron colliders
This talk presents a review of recent results for quarkonium production at
the LHC from ATLAS, CMS, LHCb, and ALICE. Production cross sections for
, , and , and production ratios for
are found to be in good agreement with predictions from
non-relativistic QCD. In contrast, spin-alignment (polarization) measurements
seem to disagree with all theoretical predictions. Some other production
channels useful for investigating quarkonium hadroproduction mechanisms are
also considered.Comment: Proceedings for The Second Annual Conference on Large Hadron Collider
Physic
Constraints on Nucleon Decay via "Invisible" Modes from the Sudbury Neutrino Observatory
Data from the Sudbury Neutrino Observatory have been used to constrain the
lifetime for nucleon decay to ``invisible'' modes, such as n -> 3 nu. The
analysis was based on a search for gamma-rays from the de-excitation of the
residual nucleus that would result from the disappearance of either a proton or
neutron from O16. A limit of tau_inv > 2 x 10^{29} years is obtained at 90%
confidence for either neutron or proton decay modes. This is about an order of
magnitude more stringent than previous constraints on invisible proton decay
modes and 400 times more stringent than similar neutron modes.Comment: Update includes missing efficiency factor (limits change by factor of
2) Submitted to Physical Review Letter
Search for a dark vector gauge boson decaying to using decays
We report a search for a dark vector gauge boson that couples to
quarks in the decay chain , . No signal is found and we set a
mass-dependent limit on the baryonic fine structure constant of in the mass range of 290 to 520 MeV/. This analysis is
based on a data sample of 976 fb collected by the Belle experiment at
the KEKB asymmetric-energy collider.Comment: 6 pages, 4 figure
Measurement of via initial state radiation at Belle
The process (=1, 2) is studied via initial
state radiation using 980 fb of data at and around the
(=1, 2, 3, 4, 5) resonances collected with the Belle detector at the KEKB
asymmetric-energy collider. No significant signal is observed except
from decays. Upper limits on the cross sections between
and are determined at the 90% credibility
level, which range from few pb to a few tens of pb. We also set upper limits on
the decay rate of the vector charmonium [), , and
] and charmoniumlike [, , and ] states
to .Comment: Accepted by PR
Measurement of the Total Active 8B Solar Neutrino Flux at the Sudbury Neutrino Observatory with Enhanced Neutral Current Sensitivity
The Sudbury Neutrino Observatory (SNO) has precisely determined the total
active (nu_x) 8B solar neutrino flux without assumptions about the energy
dependence of the nu_e survival probability. The measurements were made with
dissolved NaCl in the heavy water to enhance the sensitivity and signature for
neutral-current interactions. The flux is found to be 5.21 +/- 0.27 (stat) +/-
0.38 (syst) x10^6 cm^{-2}s^{-1}, in agreement with previous measurements and
standard solar models. A global analysis of these and other solar and reactor
neutrino results yields Delta m^{2} = 7.1^{+1.2}_{-0.6}x10^{-5} ev^2 and theta
= 32.5^{+2.4}_{-2.3} degrees. Maximal mixing is rejected at the equivalent of
5.4 standard deviations.Comment: Submitted to Phys. Rev. Let
Search for B+ -> l+ nu gamma decays with hadronic tagging using the full Belle data sample
We search for the decay B+ -> l+ nu gamma with l+ = e+ or mu+ using the full
Belle data set of 772 x 10^6 BBbar pairs, collected at the Y(4S) resonance with
the Belle detector at the KEKB asymmetric-energy e+e- collider. We reconstruct
one B meson in a hadronic decay mode and search for the B+ -> l+ nu gamma decay
in the remainder of the event. We observe no significant signal within the
phase space of E_gamma^sig > 1 GeV and obtain upper limits of BR(B+ -> e+ nu
gamma) mu+ nu gamma) l+ nu
gamma) < 3.5 x 10^-6 at 90 % credibility level.Comment: Submitted to Phys. Rev.
Invariant-mass and fractional-energy dependence of inclusive production of di-hadrons in annihilation at 10.58 GeV
The inclusive cross sections for di-hadrons of charged pions and kaons
() in electron-positron annihilation are reported. They
are obtained as a function of the total fractional energy and invariant mass
for any di-hadron combination in the same hemisphere as defined by the thrust
event-shape variable and its axis. Since same-hemisphere di-hadrons can be
assumed to originate predominantly from the same initial parton, di-hadron
fragmentation functions are probed. These di-hadron fragmentation functions are
needed as an unpolarized baseline in order to quantitatively understand related
spin-dependent measurements in other processes and to apply them to the
extraction of quark transversity distribution functions in the nucleon. The
di-hadron cross sections are obtained from a data sample
collected at or near the resonance with the Belle detector at
the KEKB asymmetric-energy collider.Comment: 21 pages, 18 figures plus 25 figures in supplemental material,
submitted to PR
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