An Effective pTp_T Cutoff for the Isolalated Lepton Background from Bottom Decay --

There is a strong correlation between the $p_T$ and isolation of the lepton coming from $B$ decay. Consequently the isolated lepton background from $B$ decay goes down rapidly with increasing lepton $p_T$; and there is a $p_T$ cutoff beyond which it effectively vanishes. For the isolation cut of $E^{AC}_T < 10$ GeV, appropriate for LHC, the lepton $p_T$ cutoff is 80 GeV. This can be exploited to effectively eliminate the $B$ background from the like sign dilepton channel apropriate for Majorana particle searches, as well as the unlike sign dilepton and the single lepton channels appropriate for the top quark search. We illustrate this with a detailed analysis of the $B$ background in these channels along with the signals at LHC energy using both parton level MC and ISAJET programs.Comment: TIFR/TH/93-23 (LATEX, 20 pages, 7 figures available on request

Isobaric incompressibility of the isospin asymmetric nuclear matter

The isospin dependence of the saturation properties of asymmetric nuclear matter, particularly the incompressibility $K_\infty (X) = K_\infty + K_\tau X^2 + O(X^4)$ at saturation density is systematically studied using density dependent M3Y interaction. The $K_\tau$ characterizes the isospin dependence of the incompressibility at saturation density $\rho_0$. The approximate expression $K_{asy} \approx K_{sym}-6L$ is often used for $K_\tau$ where $L$ and $K_{sym}$ represent, respectively, the slope and curvature parameters of the symmetry energy at $\rho_0$. It can be expressed accurately as $K_\tau=K_{sym}-6L-\frac{Q_0}{K_\infty}L$ where $Q_0$ is the third-order derivative parameter of symmetric nuclear matter at $\rho_0$. The results of this addendum to Phys. Rev. C 80, 011305(R) (2009) indicate that the $Q_0$ contribution to $K_\tau$ is not insignificant.Comment: 4 pages including 1 table and 1 figur

A Mass Formula from Light to Hypernuclei

Simultaneous description of ordinary and hypernuclei masses by a single mass formula has been a great challenge in nuclear physics. Hyperon-separation energies of about forty Lambda($\Lambda$), three Lambda-Lambda($\Lambda\Lambda$), one Sigma($\Sigma$) and seven Cascade($\Xi$) hypernuclei have been experimentally found. Many of these nuclei are of light masses. We prescribe a new mass formula, called BWMH, which describes the normal and hypernuclei on the same footing. It is based on the modified-Bethe-Weizs\"acker mass formula (BWM). BWM is basically an extension of the Bethe-Weizs\"acker mass formula (BW) for light nuclei. The parameters of BWM were optimized by fitting about 3000 normal nuclei available recently. The original Bethe-Weizs\"acker mass formula (BW) was designed for medium and heavy mass nuclei and it fails for light nuclei. Two earlier works on hypernuclei based on this BW show some limitations. The BWMH gives improved agreement with the experimental data for the line of stability, one-neutron separation energy versus neutron number spectra of normal nuclei, and the hyperon-separation energies from hypernuclei. The drip lines are modified for addition of a $\Lambda$ hyperon in a normal nucleus.Comment: Presented at the "XXIX Mazurian Lakes Conference on Physics: Nuclear Physics and the Fundamental Processes, Piaski, Poland, August 30 - September 6, 2005." (7 pages, 1 Table, 1 Figure