scholarly journals UNDERSTANDING OPEN-CHARM MESONS

2007 ◽  
Vol 22 (02n03) ◽  
pp. 550-554
Author(s):  
J. VIJANDE ◽  
F. FERNÁNDEZ ◽  
A. VALCARCE

We present a theoretical framework that accounts for the new DJ and DsJ mesons measured in the open-charm sector. These resonances are properly described if considered as a mixture of conventional P–wave quark-antiquark states and four-quark components. The narrowest states are basically P–wave quark-antiquark mesons, while the dominantly four-quark states are shifted above the corresponding two-meson threshold. We study the electromagnetic decay widths as basic tools to scrutiny their nature.

Author(s):  
Amruta Mishra ◽  
S. P. Misra

The mass modifications of the open charm ([Formula: see text] and [Formula: see text]) mesons, and their effects on the decay widths [Formula: see text] as well as of the charmonium state, [Formula: see text] to open charm mesons ([Formula: see text]), are investigated in the presence of strong magnetic fields. These are studied accounting for the mixing of the pseudoscalar ([Formula: see text]) and vector ([Formula: see text]) mesons ([Formula: see text], [Formula: see text] mixings), with the mixing parameter, [Formula: see text] of a phenomenological three-point ([Formula: see text]) vertex interaction determined from the observed radiative decay width of [Formula: see text]. For charged [Formula: see text] mixing, this parameter is dependent on the magnetic field, because of the Landau level contributions to the vacuum masses of these mesons. The masses of the charged [Formula: see text] and [Formula: see text] mesons modified due to [Formula: see text] mixing, in addition, have contributions from the lowest Landau levels in the presence of a strong magnetic field. The effects of the magnetic field on the decay widths are studied using a field theoretical model of composite hadrons with quark (and antiquark) constituents. The matrix elements for these decays are evaluated using the light quark–antiquark pair creation term of the free Dirac Hamiltonian for the constituent quark field, with explicit constructions for the charmonium state [Formula: see text], the open charm ([Formula: see text], [Formula: see text], [Formula: see text]) mesons and the pion states in terms of the constituent quark fields. The parameter for the charged [Formula: see text] mixing is observed to increase appreciably with increase in the magnetic field. This leads to dominant modifications to their masses, and hence the decay widths of charged [Formula: see text] as well as [Formula: see text] at large values of the magnetic field. The modifications of the masses and decay widths of the open and hidden charm mesons in the presence of strong magnetic fields should have observable consequences on the production of the open charm ([Formula: see text] and [Formula: see text]) mesons as well as of the charmonium states resulting from noncentral ultra-relativistic heavy ion collision experiments.


2011 ◽  
Vol 84 (1) ◽  
Author(s):  
C. E. Jiménez-Tejero ◽  
A. Ramos ◽  
L. Tolós ◽  
I. Vidaña

2019 ◽  
Vol 34 (31) ◽  
pp. 1950195 ◽  
Author(s):  
Wei Wang ◽  
Ruilin Zhu

Experimental measurements of decay branching fractions of semitaunic and semimuonic [Formula: see text] into [Formula: see text] have challenged the lepton flavor universality in standard models with about two standard deviations. In this paper, we first investigate the unitary constraint on form factors of [Formula: see text] meson into [Formula: see text]-wave and [Formula: see text]-wave charmonium. Such constraint leads to the exploration of the [Formula: see text] and other ratios [Formula: see text], [Formula: see text], and [Formula: see text] in a model-independent way. These results together with future experimental measurements can be used to explore the lepton flavor universality in a more systematic way. In addition, we point out that the helicity-dependent ratios [Formula: see text] and [Formula: see text] can also provide complementary information.


2018 ◽  
Vol 171 ◽  
pp. 21001
Author(s):  
M. Deveaux ◽  
A. Aduszkiewicz ◽  
Y. Ali ◽  
M. Baszczyk ◽  
W. Brylinski ◽  
...  

Charmonium production in heavy ion collisions is considered as an important diagnostic probe for studying the phase diagram of strongly interacting matter for potential phase transitions. The interpretation of existing data from the CERN SPS is hampered by a lack of knowledge on the properties of open charm particle production in the fireball. Moreover, open charm production in heavy ion collisions by itself is poorly understood. To overcome this obstacle, the NA61/SHINE was equipped with a Small Acceptance Vertex Detector (SAVD), which is predicted to make the experiment sensitive to open charm mesons produced in A-A collisions at the SPS top energy. This paper will introduce the concept and the hardware of the SAVD. Moreover, first running experience as obtained in a commissioning run with a 150 AGeV/c Pb+Pb collision system will be reported.


1976 ◽  
Vol 13 (1) ◽  
pp. 82-86 ◽  
Author(s):  
J. F. Gunion ◽  
L. F. Li

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