493 research outputs found
Pseudorapidity shape of elliptic flow as signature for fast equilibration in relativistic heavy-ion collisions at energies up to sqrt(s) = 200 GeV
The implications of parton recombination processes on the dynamics of
ultrarelativistic heavy-ion reactions are investigated. To do so, the
quark-gluon string transport model has been extended for partonic recombination
and fusion processes. Parton recombination leads to short equilibration times
and improves significantly on the theoretical description of measured directed
and elliptic flow, i.e., v_1 and v_2, distributions in Au+Au collisions at
sqrt(s) = 200 GeV, in particular what concerns their pseudorapidity dependence.
The shape of v_2(eta) is found to be closely related to fast thermalization.Comment: 7 pages (revtex4) with 4 figures, v3: substantially extended
description and discussion of the model and its results, accepted for
publication in Phys. Rev.
Polarization and time-resolved photoluminescence spectroscopy of excitons in MoSe2 monolayers
We investigate valley exciton dynamics in MoSe2 monolayers in polarization-
and time-resolved photoluminescence (PL) spectroscopy at 4K. Following
circularly polarized laser excitation, we record a low circular polarization
degree of the PL of typically . This is about 10 times lower than the
polarization induced under comparable conditions in MoS2 and WSe2 monolayers.
The evolution of the exciton polarization as a function of excitation laser
energy and power is monitored in PL excitation (PLE) experiments. Fast PL
emission times are recorded for both the neutral exciton of ps and for
the charged exciton (trion) of 12 ps.Comment: 4 pages, 3 figure
The exclusive rare decays B -> K l(bar) l and B_c -> D(D*) l(bar) l in a relativistic quark model
We study the exclusive rare decay B -> K l(bar) l. We calculate the relevant
form factors within a relativistic constituent quark model, for the first time
without employing the impulse approximation. The calculated form factors are
used to evaluate differential decay rates and polarization observables. We
present results on the q2-dependence of a set of observables with and without
long-distance contributions. A similar analysis is done for the exclusive rare
decays B_c -> D (D*) l(bar) l with special emphasis on the cascade decay B_c ->
D* (-> D pi) l(bar) l. We derive a four-fold angular decay distribution for
this process in terms of helicity amplitudes including lepton mass effects. The
four-fold angular decay distribution allows to define a number of physical
observables which are amenable to measurement. We compare our results with the
results of other studies.Comment: 28 pages, 12 figure
Semileptonic decays of double heavy baryons in a relativistic constituent three-quark model
We study the semileptonic decays of double heavy baryons using a manifestly
Lorentz covariant constituent three-quark model. We present complete results on
transition form factors between double-heavy baryons for finite values of the
heavy quark/baryon masses and in the heavy quark symmetry limit which is valid
at and close to zero recoil. Decay rates are calculated and compared to each
other in the full theory, keeping masses finite, and also in the heavy quark
limit.Comment: 20 pages, 2 figure
Charmed baryon Sigmac(2800) as a ND hadronic molecule
The isotriplet Sigmac(2800) baryon with possible quantum numbers J(P) =
1/2(+), 1/2(-) or 3/2(+), 3/2(-) is considered as a hadronic molecule composed
of a nucleon and a D meson. We determine the strong two-body decay widths
Sigmac to Lambdac + pi which are shown to be consistent with current data for
the J(P) = 1/2(+) and J(P) = 3/2(-) assignments.Comment: 8 pages, 2 figure
Sterile neutrinos in neutrinoless double beta decay
We study possible contribution of the Majorana neutrino mass eigenstate
dominated by a sterile neutrino component to neutrinoless double beta
() decay. From the current experimental lower bound on the
-decay half-life of Ge we derive stringent constraints
on the mixing in a wide region of the values of mass. We
discuss cosmological and astrophysical status of in this mass region.Comment: 6 pages, 1 figure; v2 added comments and reference
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