scholarly journals Pathways for intramolecular relaxation in S 1 benzene

1990 ◽  
Vol 332 (1625) ◽  
pp. 189-201 ◽  
Keyword(s):  
Energy Coupling ◽  
Weak Limit ◽  
Excess Energy ◽  
Matrix Elements ◽  
Strong Limit ◽  
Decay Channels ◽  
Two Photon ◽  
Decay Behaviour ◽  
Quantum Numbers ◽  
Fast Electronic

Sub-Doppler spectra of various one- and two-photon vibronic bands of benzene are discussed and analysed to determine the pathways of intramolecular relaxation for Sx benzene. New results are presented for the 14J1q16| band of C 6 H 6 and the 14^1^ band of 13 C 6 H 6 . The decay behaviour depends strongly on the excess energy and the rotational quantum numbers rather than on the vibrational character and symmetry of the excited state. At low vibrational excess energy the pathway for intramolecular relaxation is a coupling in the strong limit between pairs of states in Sx leading to shifts of lines, whereas at intermediate excess energy coupling in the weak limit to background states in Sx is present. These background states are strongly broadened due to a fast electronic non-radiative process. The intramolecular relaxation is found to be initiated by the coupling to the broadened S 1 background states and energy can flow via these states to the T 1 or S 0 state. The rotationally selective disappearance of lines is believed to be due to an intricate interplay of the rotational dependence of the coupling matrix elements and accidental resonances, which lead to interference of possible decay channels.

scholarly journals Light-cone sum rules for proton decay

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Ulrich Haisch ◽  
Amando Hala
Keyword(s):  
Lattice Qcd ◽  
Light Cone ◽  
Sum Rules ◽  
State Of The Art ◽  
Form Factors ◽  
Baryon Number ◽  
Proton Decay ◽  
Matrix Elements ◽  
Decay Channels ◽  
Systematic Uncertainties

Abstract We estimate the form factors that parametrise the hadronic matrix elements of proton-to-pion transitions with the help of light-cone sum rules. These form factors are relevant for semi-leptonic proton decay channels induced by baryon-number violating dimension-six operators, as typically studied in the context of grand unified theories. We calculate the form factors in a kinematical regime where the momentum transfer from the proton to the pion is space-like and extrapolate our final results to the regime that is relevant for proton decay. In this way, we obtain estimates for the form factors that show agreement with the state-of-the-art calculations in lattice QCD, if systematic uncertainties are taken into account. Our work is a first step towards calculating more involved proton decay channels where lattice QCD results are not available at present.

scholarly journals Shedding Light on Hexaquarks

2018 ◽  
Vol 46 ◽  
pp. 1860033 ◽  
Author(s):  
M. Bashkanov ◽  
T. Skorodko ◽  
H. Clement ◽  
D. P. Watts
Keyword(s):  
Internal Structure ◽  
Large Set ◽  
Physical Size ◽  
Decay Channels ◽  
Quantum Numbers ◽  
New Findings ◽  
Reaction Channels ◽  
Experimental Side ◽  
Multiquark States ◽  
Made In

Several new findings in the four, five and six quark systems reheat the interest in the field of multiquark states (beyond the trivial [Formula: see text] and [Formula: see text]). A lot of progress has recently been made in the 6q sector, on both the theoretical and experimental side. A resonance like structure observed in double-pionic fusion to the deuteron, at M = 2.38 GeV with [Formula: see text] = 70 MeV and [Formula: see text] has been consistently observed in a wealth of reaction channels, supporting the existence of a resonant dibaryon state - the [Formula: see text]. These studies include measurement of all the principle strong decay channels in pn collisions in the quasifree mode by the WASA-at-COSY and HADES collaborations. The internal structure of the [Formula: see text] is largely unknown. It can contain various ”hidden color” 6q configurations, [Formula: see text] molecular states with angular momentum L = 0,2,4,6 as well as meson-assisted dressed dibaryon structures. The large set of experimental data obtained to date gives some constraints on the internal structure of the [Formula: see text] dibaryon, but does not settle the issue. The [Formula: see text] is the only multiquark state which can be produced copiously at current facilities, offering unique access to information beyond its basic quantum numbers, particularly its physical size and internal structure.

SYMMETRY AND ELECTRO-OPTICAL PROPERTIES OF NANOTUBES

2002 ◽  
Vol 01 (03n04) ◽  
pp. 313-325 ◽  
Author(s):  
M. DAMNJANOVIĆ ◽  
I. MILOŠEVIĆ ◽  
T. VUKOVIĆ ◽  
B. NIKOLIĆ ◽  
E. DOBARDŽIĆ
Keyword(s):  
Carbon Nanotubes ◽  
Optical Properties ◽  
Density Functional ◽  
Tight Binding ◽  
Optical Characteristics ◽  
Optical Transitions ◽  
Matrix Elements ◽  
Selection Rules ◽  
Single Wall Carbon ◽  
Quantum Numbers

The symmetry of single-wall carbon and inorganic tubes is reviewed. For the carbon nanotubes it is used to get the full set of quantum numbers, in the efficient precision (combined density functional and tight-binding methods) calculation of electronic bands and their complete assignation, to obtain the selection rules for optical transitions and the momenta matrix elements for the Bloch eigen-states. The optical characteristics are thoroughly found, and discussed.

scholarly journals Free-free matrix-elements for two-photon opacity

2020 ◽  
Vol 34 ◽  
pp. 100717
Author(s):  
R. More ◽  
J.-C. Pain ◽  
S.B. Hansen ◽  
T. Nagayama ◽  
J.E. Bailey
Keyword(s):  
Matrix Elements ◽  
Two Photon

Quasi-particles in atomic shell theory

1970 ◽  
Vol 315 (1520) ◽  
pp. 27-37 ◽  
Keyword(s):  
Shell Theory ◽  
Particle Creation ◽  
Rotation Group ◽  
Coupling Scheme ◽  
Matrix Elements ◽  
Spin Orientation ◽  
Quasi Particle ◽  
Quantum Numbers ◽  
Fractional Parentage ◽  
Electronic Configurations

A new scheme is described for defining and classifying the states of the electronic configurations l N . The spaces for which the spin orientation is either up or down are both factored into two parts. Each of these parts (distinguished by a symbol Ɵ) corresponds to the irreducible representatio n (½ ½ ... ½ ) of the rotation group R Ɵ (2 l +1). The generators for this group are constructed from quasi-particle creation and annihilation operators. The angular momentum quantum numbers l Ɵ arising from the decomposition of (½ ½ ... ½) into representations of R Ɵ (3) can be used to couple the four parts together. No ambiguities arise when l < 9, thereby giving a very satisfactory coupling scheme. No coefficients of fractional parentage (c. f. p.) are required in the calculation of matrix elements. Simple explanations are given for some null c. f. p. and for some repeated eigenvalues of an operator that had previously been used to classify the state s of g N .

scholarly journals Radiative Decay Widths of Ground and Excited States of Vector Charmonium and Bottomonium

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Hluf Negash ◽  
Shashank Bhatnagar
Keyword(s):  
Mass Spectrum ◽  
Excited States ◽  
Mass Spectra ◽  
Reasonable Agreement ◽  
Radiative Decay ◽  
Decay Constants ◽  
Two Photon ◽  
Quantum Numbers ◽  
Decay Widths ◽  
Input Parameters

We study the radiative decay widths of vector quarkonia for the process of J/ψ(nS)→ηc(nS)γ and Υ(nS)→ηb(nS)γ (for principal quantum numbers n=1,2,3) in the framework of Bethe-Salpeter equation under the covariant instantaneous ansatz using a 4×4 form of BSE. The parameters of the framework were determined by a fit to the mass spectrum of ground states of pseudoscalar and vector quarkonia, such as ηc, ηb, J/ψ, and Υ. These input parameters so fixed were found to give good agreements with data on mass spectra of ground and excited states of pseudoscalar and vector quarkonia, leptonic decay constants of pseudoscalar and vector quarkonia, two-photon decays, and two-gluon decays of pseudoscalar quarkonia in our recent paper. With these input parameters so fixed, the radiative decay widths of ground (1S) and excited (2S,3S) states of heavy vector quarkonia (J/Ψ and Υ) are calculated and found to be in reasonable agreement with data.

scholarly journals Many-body calculations of two-photon, two-color matrix elements for attosecond delays

2019 ◽  
Vol 100 (4) ◽  
Author(s):  
Jimmy Vinbladh ◽  
Jan Marcus Dahlström ◽  
Eva Lindroth
Keyword(s):  
Matrix Elements ◽  
Many Body ◽  
Two Photon

scholarly journals Direct production of χc1 at BESIII

2019 ◽  
Vol 202 ◽  
pp. 06009
Author(s):  
Yuping Guo
Keyword(s):  
Data Analysis ◽  
Production Rate ◽  
Neutral Current ◽  
High Luminosity ◽  
Direct Production ◽  
Two Photon ◽  
Quantum Numbers ◽  
Decay Products ◽  
Electron Positron Annihilation ◽  
Electron Positron

The production of resonances in electron-positron annihilation has only been observed for states with quantum numbers JPC = 1−−, while C = +1 resonances appear only among the decay products. The direct production of the 1++ states could happen through two-photon or neutral current. Due to the smallness of the production rate, this process has never been verified experimentally. With the high luminosity and good performance of the BESIII experiment, a search of the direct production of the 1++ state in charmonium region, χc1, is undergoing with dedicated data samples around the χc1 mass. An overview of the data analysis will be presented.

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