A Modern Introduction To Particle Physics (3rd Edition)

The book provides a comprehensive account of particle physics linking various aspects of particle physics in a coherent manner. This self-contained book not only cover basic concepts and recent developments but also overlaps between Astrophysics, Cosmology and Particle Physics, known as astroparticle physics. Several appendices are included to make the book self-contained

SUL(4)×U(1)SU_{L}(4)\times U(1) model for electroweak unification and sterile neutrinos

Some of basic problems in neutrino physics such as new energy scales, the enormous gap between neutrino masses and the lightest charged fermion mass, possible existance of sterile neutrinos in eV mass range are studied in the local gauge group $SU_{L}(4)\times U(1)$ for electroweak unification, which does not contain fermions with exotic electric charges. It is shown that neutrino mass spectrum can be decoupled from that of the other fermions. Further normal seesaw mechanism for neutrinos, with right handed neutrino Majorana masses to be of order $M\gg M_{\text{weak}}$ as well a new eV-scale can be accomodated. The eV-scale seesaw may manifest itself in experiments like Liquid Scintilation Neutrino Detector (LSND) and MiniBooNE (MB) experimental results and future neutrino experiments.Comment: 13 page

Boson mass spectrum in SU(4)L⊗U(1)YSU(4)_L\otimes U(1)_Y model with exotic electric charges

The boson mass spectrum of the electro-weak \textbf{$SU(4)_{L}\otimes U(1)_{Y}$} model with exotic electric charges is investigated by using the algebraical approach supplied by the method of exactly solving gauge models with high symmetries. Our approach predicts for the boson sector a one-parameter mass scale to be tuned in order to match the data obtained at LHC, LEP, CDF.Comment: 12 pages, 1 Table with numerical estimates and 1 Figure added, mistaken results correcte

SU_L(4) x U(1) model for electroweak unification

After some general remarks about SU_L(4) electroweak unification, the model is extended to SU_L(4)xU_X(1) to accomodate fractionally charged quarks. The unification scale is expected to be in TeV region. A right-handed Majorana neutrino along with known lepton are put in the fundamental representation of SU_L(4) with Y_X=0. The see-saw mechanism for neutrino masses and flavor mixing in neutrino sector is a natural feature of the model. The lepton number violating processes can occure through dilepton gauge bosons contained in the model.Comment: RevTeX, 9 pages, no figure: replaced with revised versio

Off-diagonal structure of neutrino mass matrix in see-saw mechanism and electron-muon-tau lepton universality

By a simple extension of the standard model in which ($e-\mu -\tau$) universality is not conserved, we present a scenario within the framework of see-saw mechanism in which the neutrino mass matrix is strictly off-diagonal in the flavor basis. We show that a version of this scenario can accomodate the atmospheric $\nu_\mu -\nu_\tau$ neutrino oscillations and $\nu_\mu -\nu_e$ oscillations claimed by the LSND collaboration. PACS: 14.60.Pq; 14.60.St;13.15.+gComment: 5 pages, Revtex, 1 figure: The model accomodate another version which explains atmospheric neutrino data and the observed solar neutrino oscillations (large angle solution). In the previous version the value of \lambda parameter is changed to the expected one. This version now accomodates LSND result and solar neutrino oscillations (small angle MSW solution

Vector Meson Contributions in epsilon'/epsilon

The CP violating parameter epsilon'/epsilon is computed using the low-energy dynamics of a chiral theory supplemented by vector resonances. The divergent contributions coming from strong pi-pi scattering are tamed by vector-meson exchange terms. This amounts to softening the fast growing high-energy behaviour of pi-pi scattering. The final result for epsilon'/epsilon shows a smooth dependence on the cut-off where low energy dynamics is matched with that of QCD.Comment: 11 pages, 2 figures. published versio

Two body non-leptonic Λb\Lambda_b decays in quark model with factorization ansatz

The two body non-leptonic $\Lambda_b$ decays are analyzed in factorization approximation, using quark model, $\xi = 1 / N_c$ as a free parameter. It is shown that the experimental branching ratio for $\Lambda_b \longrightarrow \Lambda {J/\psi}$ restricts $\xi$ and this ratio can be understood for a value of $\xi$ which lies in the range $0 \leq \xi \leq 0.5$ suggested by two body B meson decays. The branching ratios for $\Lambda_b \longrightarrow \Lambda_{c} D^*_s(D_s)$ are predicted to be larger than the previous estimates. Finally it is pointed that CKM-Wolfenstein parameter $\rho^2 + \eta^2$, where $\eta$ is CP phase, can be determined from the ratio of widths of $\Lambda_b \longrightarrow \Lambda \bar{D}$ and $\Lambda_b \longrightarrow \Lambda {J/\psi}$ or that of $\Lambda_b \longrightarrow p D_s$ and $\Lambda_b \longrightarrow \Lambda_c D_s$ independent of the parameter $\xi$.Comment: 18 pages, latex, 1 figure available on request, please send any questions or comments to [email protected]

Spin-orbit splittings in heavy-light mesons and Dirac equation

The spin-orbit splitting in heavy-light mesons is seen to be suppressed experimentally. It is shown that it can be understood qualitatively in the frame work of Dirac theory. An alternative derivation of a relativistic dynamical symmetry for the Dirac Hamiltonian, which suppresses spin orbit splitting, is also given. However it is shown that such a symmetry is not needed since the spin-orbit splitting in Dirac theory with Coulomb like potential (as is the case for the one gluon exchange potential in pQCD) is small anyway.Comment: 9 pages, 1 fi