1,609 research outputs found
New physics solutions for and
Recent measurements of have reduced tension with the Standard Model
prediction. Taking all the present data into account, we obtain the values of
the Wilson coefficients of each new physics four-fermion operator of a given
Lorentz structure. We find that the combined data rule out most of the
solutions based on scalar/pseudoscalar operators. By studying the
inter-relations between different solutions, we find that there are only four
allowed solutions, which are based on operators with , linear
combination of and , tensor and linear combination of
scalar/pseudoscalar and tensor structure. We demonstrate that the need for new
physics is driven by those measurement of and where the
lepton is not studied. Further, we show that new physics only in is not compatible with the full set of observables in the
decays and .Comment: 16 pages, 1 figure (Accepted for publication in JHEP
Re-examining sin(2beta) and Delta m(d) from evolution of B(d) mesons with decoherence
In the time evolution of neutral meson systems, a perfect quantum coherence
is usually assumed. The important quantities of the B(d) system, such as sin
(2beta) and Delta m(d), are determined under this assumption. However, the
meson system interacts with its environment. This interaction can lead to
decoherence in the mesons even before they decay. In our formalism this
decoherence is modelled by a single parameter lambda. It is desirable to
re-examine the procedures of determination of sin(2beta) and Delta m(d) in
meson systems with decoherence. We find that the present values of these two
quantities are modulated by lambda. Re-analysis of B(d) data from B-factories
and LHCb can lead to a clean determination of lambda, sin(2beta) and Delta
m(d).Comment: Version accepted for publication in Physics Letters
Resolving the octant of theta23 with T2K and NOvA
Preliminary results of MINOS experiment indicate that theta23 is not maximal.
Global fits to world neutrino data suggest two nearly degenerate solutions for
theta23: one in the lower octant (LO: theta23 < 45 degree) and the other in the
higher octant (HO: theta23 > 45 degree). numu to nue oscillations in superbeam
experiments are sensitive to the octant and are capable of resolving this
degeneracy. We study the prospects of this resolution by the current T2K and
upcoming NOvA experiments. Because of the hierarchy-deltacp degeneracy and the
octant-deltacp degeneracy, the impact of hierarchy on octant resolution has to
be taken into account. As in the case of hierarchy determination, there exist
favorable (unfavorable) values of deltacp for which octant resolution is easy
(challenging). However, for octant resolution the unfavorable deltacp values of
the neutrino data are favorable for the anti-neutrino data and vice-verse. This
is in contrast to the case of hierarchy determination. In this paper, we
compute the combined sensitivity of T2K and NOvA to resolve the octant
ambiguity. If sin^2\theta23 =0.41, then NOvA can rule out all the values of
theta23 in HO at 2 sigma C.L., irrespective of the hierarchy and deltacp.
Addition of T2K data improves the octant sensitivity. If T2K were to have equal
neutrino and anti-neutrino runs of 2.5 years each, a 2 sigma resolution of the
octant becomes possible provided sin^2\theta23 \leq 0.43 or \geq 0.58 for any
value of deltacp.Comment: 27 pages, 38 pdf figures, 1 table. New figures are given in the
results section to show the octant discovery reach as a function of true
theta23 and true CP phase. Few changes in the abstract, results and
conclusions section to incorporate the new results. Published in JHE
Meson Masses and Mixing Angles in 2+1 Flavor Polyakov Quark Meson Sigma Model and Symmetry Restoration Effects
The meson masses and mixing angles have been calculated for the scalar and
pseudoscalar sector in the framework of the generalized 2+1 flavor Polyakov
loop augmented quark meson linear sigma model. We have given the results for
two different forms of the effective Polyakov loop potential. The comparison of
results with the existing calculations in the bare 2+1 quark meson linear sigma
model, shows that the restoration of chiral symmetry becomes sharper due to the
influence of the Polyakov loop potential. We find that inclusion of the
Polyakov loop in quark meson linear sigma model together with the presence of
axial anomaly, triggers an early and significant melting of the strange
condensate. We have examined how the inclusion of the Polyakov loop
qualitatively and quantitatively affects the convergence in the masses of the
chiral partners in pseudoscalar (, , , ) and scalar
(, , ,) meson nonets as the temperature is varied on
the reduced temperature scale. The role of anomaly in determining the
isoscalar masses and mixing angles for the pseudoscalar ( and )
and scalar ( and )meson complex, has also been investigated in the
Polyakov quark meson linear sigma model. The interplay of chiral symmetry
restoration effects and the setting up of restoration trend has been
discussed and analyzed in the framework of the presented model calculations.Comment: 15 pages, 8 figures, 4 table
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