The Quark-Diquark model description of double charm baryons Department of Physics Sardar Patel University Vallabh Vidyanagar-388 120, Gujarat, INDIA

Outline of talk Introduction Methodology Magnetic moments of the double charmed baryons Semileptonic decay Results and discussions

Introduction The investigation of properties of hadrons containing heavy quarks is of great interest in understanding the dynamics of QCD at the hadronic scale. The predictions about the heavy baryon mass spectrum have become a subject of renewed interest due to the experimental facilities at Belle, BABAR, DELPHI, CLEO, CDF etc. These experimental groups have been successful in discovering heavy baryonic states along with other heavy flavour mesonic states and it is expected that more heavy flavour baryon states will be detected in near future. Recently, the SELEX Collaboration has reported the discovery of ccd with a mass of 3.519 GeV. However, other groups such as BABAR , BELLE and FOCUS have all failed to confirm this state. So there is a demand to review this state both theoretically and experimentally. Baryons containing two heavy quarks are important and interesting systems to study the quark-diquark structure of baryons and to understand the dynamics of three body systems particularly here, the motion of the light quark in the vicinity of heavy quarks.

Though the experimental and theoretical data on the properties of heavy flavour mesons are available plenty in literature, the masses of most of the baryons containing two heavy flavours have not been well established experimentally. Many of these hadron resonances expected to be observed experimentally, might bring many surprises in QCD spectroscopy. Most of the new states are within the heavy flavour sector with one or more heavy flavour content and some of them are far from most of the theoretical predictions. Though there are consensus among the theoretical predictions on the ground state masses, there seemed to have little agreement among the model predictions of the properties like spin-hyperfine splitting among the baryonic states, the form factors, magnetic moments etc. All these reasons make the study of the heavy flavour spectroscopy extremely rich and interesting. We report here the mass spectra and magnetic moments of ccq systems using coulomb plus power potential within the quark-diquark model of the baryon. Here the two heavy quarks are considered for the diquark states.

Methodology

Masses, mean-squared radii and velocity of the diquark(cc) levels

Spin average masses of the double charmed baryons

[33]

Magnetic Moments of Heavy Flavour Baryons

Semileptonic decay of the doubly charmed baryons

B. Guberina 1999

Results and Discussions We have employed a simple non relativistic approach with coulomb plus power law interquark potential to study the masses of the double charm baryons in the quark-diquark model. The extra states predicted in this picture would require experimental verification in support of the double heavy flavour baryons. In our results of doubly charmed baryons are found to be in accordance with other model predictions. It is important to note that the predictions of the magnetic moment of double heavy Baryons studied here are with no additional parameters. Our results on magnetic moments are compared with one of our recent predictions using hyper-central potential [Bhavin et. al 2008] as well as with relativistic (RQM) and the nonrelativistic quark model (NRQM) predictions of [Amand et. al 2006] in Table 4. The special feature of the present study to compute the magnetic moments of double heavy flavour baryons is the consideration of the effective interactions of the bound state quarks by defining an effective bound state mass to the quarks within the baryon, which vary according to different interquark potential as well as with quark compositions.

ccd-1S1s  b   Rd(0)  Md(0)  Md(1) Diff. MB(CW)  M(1/2)  M(3\2)  Diff. 0.1(1.140) 0.438 0.334 2.721 2.745 0.024 3.482 3.431 3.508 0.077 0.3(1.263) 0.245 0.435 2.825 2.856 0.030 3.507 0.076 0.5(1.328) 0.152 0.481 2.880 2.912 0.032 1.0(1.408) 0.055 0.521 2.947 2.979 ccd-1S2s 3.628 3.616 3.634 0.019 3.699 3.681 3.708 0.027 3.753 3.730 3.765 0.034 3.861 3.828 3.878 0.050 ccd-1S3s 3.680 3.674 3.683 0.010 3.803 3.792 3.809 0.017 3.906 3.890 3.914 4.134 4.106 4.149 0.043 ccd-2S1s 0.181 2.834 2.841 0.007 3.582 3.530 3.608 0.078 0.278 3.007 3.019 0.012 3.649 3.597 3.675 0.338 3.102 3.118 0.016 3.691 3.639 3.717 0.431 3.231 3.253 0.022 3.756 3.704 3.782 ccd-3S1s 0.136 2.878 2.882 0.004 3.623 3.571 0.226 3.097 3.105 0.008 3.736 3.684 3.762 0.289 3.230 3.242 3.815 3.763 3.841 0.402 3.436 3.455 3.958 3.905 3.984 0.079

ccs- 1S1s  b   Rd(0)  Md(0)  Md(1) Diff. MB(CW)  M(1/2)  M(3\2)  Diff. 0.1(1.140) 0.438 0.334 2.721 2.745 0.024 3.574 3.492 3.615 0.123 0.3(1.263) 0.245 0.435 2.825 2.856 0.030 3.565 3.490 3.602 0.112 0.5(1.328) 0.152 0.481 2.880 2.912 0.032 3.560 3.488 3.595 0.107 1.0(1.408) 0.055 0.521 2.947 2.979 3.552 3.485 3.585 0.100 ccs- 1S2s 3.748 3.730 3.757 0.027 3.802 3.778 3.814 0.036 3.842 3.813 3.856 0.043 3.918 3.879 3.937 0.058 ccs-1S3s 3.806 3.797 3.811 0.013 3.909 3.894 3.916 0.022 3.993 3.973 4.003 4.172 4.140 4.188 0.048 ccs-2S1s 0.181 2.834 2.841 0.007 3.673 3.590 3.715 0.125 0.278 3.007 3.019 0.012 3.731 3.655 3.769 0.114 0.338 3.102 3.118 0.016 3.768 3.695 3.804 0.109 0.431 3.231 3.253 3.825 3.859 0.102 ccs-3S1s 0.136 2.878 2.882 0.004 3.714 3.631 3.756 0.126 0.226 3.097 3.105 0.008 3.818 3.741 0.115 0.289 3.230 3.242 3.891 3.928 0.111 0.402 3.436 3.455 0.019 4.026 3.957 4.061 0.104

Acknowledgement References:

Thanks Prof. P C Vinodkumar Dr. J N Pandya (MSU,Vadodara), Dr. Ajay Kumar Rai (SVNIT, Surat), Dr. C J Clement (St. Xavier Sci. College, Ahmedabad), Dr. R H Parmar (Modasa Sci. College, Modasa), Mr. Ajay Majethiya (KITRC, Kalol), Ms. Shereena Joseph (Delhi), Mr. Arpit Parmar and Mr. Kaushal Thakkar. Part of this work is done with a financial support from DST, New Delhi, under a Major Research Project SR/S2-HEP-20/2006.

Semileptonic decay of the doubly charmed baryons

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The Quark- Diquark Model Description of Double Charmed Baryons Ajay Majethiya Department of Physics, Sardar Patel University, Vallabh Vidyanagar- 388120, Gujarat, India. *ajay.phy@gmail.com