scholarly journals Strong decays of $${\bar{D}}^{*}K^{*}$$ molecules and the newly observed $$X_{0,1}$$ states

Author(s):  
Yin Huang ◽  
Jun-Xu Lu ◽  
Ju-Jun Xie ◽  
Li-Sheng Geng

AbstractLately, the LHCb Collaboration reported the discovery of two new states in the $$B^+\rightarrow D^+D^- K^+$$ B + → D + D - K + decay, i.e., $$X_0(2866)$$ X 0 ( 2866 ) and $$X_1(2904)$$ X 1 ( 2904 ) . In the present work, we study whether these states can be understood as $${\bar{D}}^*K^*$$ D ¯ ∗ K ∗ molecules from the perspective of their two-body strong decays into $$D^-K^+$$ D - K + via triangle diagrams and three-body decays into $${\bar{D}}^*K\pi $$ D ¯ ∗ K π . The coupling of the two states to $${\bar{D}}^*K^*$$ D ¯ ∗ K ∗ are determined from the Weinberg compositeness condition, while the other relevant couplings are well known. The obtained strong decay width for the $$X_0(2866)$$ X 0 ( 2866 ) state, in marginal agreement with the experimental value within the uncertainty of the model, hints at a large $${\bar{D}}^*K^*$$ D ¯ ∗ K ∗ component in its wave function. On the other hand, the strong decay width for the $$X_1(2904)$$ X 1 ( 2904 ) state, much smaller than its experimental counterpart, effectively rules out its assignment as a $${\bar{D}}^*K^*$$ D ¯ ∗ K ∗ molecule.

1994 ◽  
Vol 08 (01) ◽  
pp. 29-40 ◽  
Author(s):  
KAZUMOTO IGUCHI

The theory of localization in the Schrödinger operators with arbitrary deterministic potential sequences is studied herein. We classify all the systems of arbitrary substitutions into three categories in terms of the number of constituent atoms, r. If r=1, then all the states in the system belong to only extended states. If r=2, there appears a great variety of the systems on which the localization depends, where some systems show the transition between the extended and the critical states. On the other hand, if r≥3, then there is the universal criticality of the spectrum — all the states in the spectrum belong to only critical states, where the wave function is self-similar or fractal. Surprisingly, this result does not depend on any substitution scheme. Thus, the localization is absent in OUT systems.


2020 ◽  
Vol 80 (9) ◽  
Author(s):  
Yin Huang ◽  
Lisheng Geng

AbstractIn this work, we study the strong decays of the newly observed $$\varXi (1620)^0$$ Ξ ( 1620 ) 0 assuming that it is a meson-baryon molecular state of $$\varLambda {\bar{K}}$$ Λ K ¯ and $$\varSigma {\bar{K}}$$ Σ K ¯ . We consider four possible spin-parity assignments $$J^P=1/2^{\pm }$$ J P = 1 / 2 ± and $$3/2^{\pm }$$ 3 / 2 ± for the $$\varXi (1620)^0$$ Ξ ( 1620 ) 0 , and evaluate its partial decay width into $$\varXi \pi $$ Ξ π and $$\varXi \pi \pi $$ Ξ π π via hadronic loops with the help of effective Lagrangians. In comparison with the Belle data, the calculated decay width favors the spin-party assignment $$1/2^-$$ 1 / 2 - while the other spin-parity assignments do not yield a decay width consistent with data in the molecule picture. We find that about 52–68% of the total width comes from the $${\bar{K}}\varLambda $$ K ¯ Λ channel, while the rest is provided by the $${\bar{K}}\varSigma $$ K ¯ Σ channel. As a result, both channels are important in explaining the strong decay of the $$\varXi (1620)^0$$ Ξ ( 1620 ) 0 . In addition, the transition $$\varXi (1620)^0\rightarrow \pi \varXi $$ Ξ ( 1620 ) 0 → π Ξ is the main decay channel in the $$J^{P}=1/2^{-}$$ J P = 1 / 2 - case, which almost saturates the total width. These information are helpful to further understand the nature of the $$\varXi (1620)^0$$ Ξ ( 1620 ) 0 .


1967 ◽  
Vol 8 (1) ◽  
pp. 47-70 ◽  
Author(s):  
Ernest Gellner

Looking at the contemporary world, two things are obvious: democracy is doing rather badly, and democracy is doing very well. ‘New states are born free, yet everywhere they are in chains.’ Democracy is doing very badly in that democratic institutions have fallen by the wayside in very many of the newly independent ‘transitional’ societies, and they are precarious elsewhere. Democracy, on the other hand, is doing extremely well in as far as it is almost (though not quite) universally accepted as a valid norm. It is almost as if its success as a norm of legitimacy were inversely related to its success in concrete implementation.


1998 ◽  
Vol 11 (2) ◽  
pp. 616-621 ◽  
Author(s):  
S. L. W. Mcmillan ◽  
C. Pryor ◽  
E. S. Phinney

Binary stars in a globular cluster (hereafter, GC) may be primordial (i.e. formed along with the cluster), or the result of cluster dynamics. “Dynamical” binaries can result from conservative three-body encounters (e.g. Spitzer, 1987) if a third star can carry away enough kinetic energy to leave two others bound, or from dissipative two-body encounters, if two stars happen to pass within a few stellar radii of one other (Fabian, Pringle, & Rees, 1975). Such non-primordial systems are likely to be found primarily in evolved GC cores, both because conditions are more favorable for making them there, and because of mass segregation. Knowledge of the formation process allows reasonable estimates to be made of their mass and energy distributions. The initial spatial, mass, and energy distributions of primordial binaries, on the other hand, are largely unknown.


1979 ◽  
Vol 53 ◽  
pp. 330-333
Author(s):  
N. Visvanathan ◽  
D. T. Wickramasinghe

VV Puppis, a dwarf-nova binary with a 100 min period (Herbig 1960) was observed on two occasions. On 2nd February 1979, VV Puppis was in a faint inactive state. On the other hand it was bright and active on 14th June 1979. Spectral and polarimetry observations were made on both these occasions using IDS (modified as polarimeter) at the f/15 Cassegrain focus of the 4 meter Anglo-Australian Telescope. Spectral range covered was from 3600 Å to 7000 Å with a resolution of 10 Å. The star and sky apertures both were of size 3 × 4 sec of arc and 40 sec apart.


2021 ◽  
Vol 81 (2) ◽  
Author(s):  
Rui Chen

AbstractIn our former work [arXiv:2011.07214], the $$P_{cs}(4459)$$ P cs ( 4459 ) observed by the LHCb Collaboration can be explained as a coupled strange hidden-charm $$\Xi _c{\bar{D}}^*/\Xi _c^*{\bar{D}}/\Xi _c'{\bar{D}}^*/\Xi _c^*{\bar{D}}^*$$ Ξ c D ¯ ∗ / Ξ c ∗ D ¯ / Ξ c ′ D ¯ ∗ / Ξ c ∗ D ¯ ∗ molecule with $$I(J^P)=0(3/2^-)$$ I ( J P ) = 0 ( 3 / 2 - ) . Here, we further discuss the two-body strong decay behaviors of the $$P_{cs}(4459)$$ P cs ( 4459 ) in the meson-baryon molecular scenario by input the former obtained bound solutions. Our results support the $$P_{cs}(4459)$$ P cs ( 4459 ) as the strange hidden-charm $$\Xi _c{\bar{D}}^*$$ Ξ c D ¯ ∗ molecule with $$I(J^P)=0(3/2^-)$$ I ( J P ) = 0 ( 3 / 2 - ) . The relative decay ratio between $$\Lambda _cD_s^*$$ Λ c D s ∗ and $$J/\psi \Lambda $$ J / ψ Λ is around 10, where the partial decay width for the $$\Lambda _cD_s^*$$ Λ c D s ∗ channel is around 0.6 to 2.0 MeV.


1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.


Author(s):  
A. V. Crewe

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.


Author(s):  
K.H. Westmacott

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.


2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.


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