We introduce the spin-charge separation mechanism to the quark-lepton unification models which consider the lepton number as the fourth color. In certain finite-density systems, quarks and leptons are decomposed into spinons and chargons, which carry the spin and charge degrees of freedom respectively. Neutrinos can be related to the spinons with respect to the electric-charge and spin separation in the early universe or other circumstances. Some effective, probably universal couplings between the spinon sector and the chargon sector are derived and a phenomenological description for the chargon condensate is proposed. It is then demonstrated that the spinon current can induce vorticity in the chargon condensate, and spinon zero modes are trapped in the vortices, forming spinon-vortex bound states. In cosmology this configuration may lead to the emission of extremely high energy neutrinos when vortices split and reconnect.
The 2+1 dimensional (2 space dimensions and 1 time dimension) Transverse Lattice is constructed using the Color Dielectric formalism. The dynamics of the Color Dielectric link fields are not known from first principles, so an ansatz for the effective action is made, which is truncated at fourth order in the fields. Since the Transverse Lattice is a Light-Front field theory, it lacks manifest rotational invariance. This lack of manifest rotational invariance is exploited to determine the couplings in the effective action by calculating the Quark/Anti-quark Potential, an observable that is very …
We investigate the spectrum and wave functions of {\bar q}'q' bound states for heavy fourth generation quarks (q') that have a very small mixing with the three observed generations of standard model quarks. Such bound states come with different color, spin and flavor quantum numbers. Since the fourth generation Yukawa coupling, λ_{q'}, is large we include all perturbative corrections to the potential between the heavy quark and antiquark of order λ_{q'}^2N_c/16π^2 where N_c is the number of colors, as well as relativistic corrections suppressed by (v/c)^2. We find that the lightest fourth gene…
We propose an extension of the Standard Model in which baryon number is promoted to be part of a non-Abelian gauge symmetry at high energies. Specifically, we consider the gauge group SU(4) x SU(2)_L x U(1)_X, where the SU(4) unifies baryon number and color. This symmetry is spontaneously broken down to the Standard Model gauge group at a scale which can be as low as a few TeV. The SU(4) structure implies that each SM quark comes along with an uncolored quark partner, the lightest of which is stabilized by the generalized baryon number symmetry and can play the role of dark matter. We explore …
The possibility to violate baryon or lepton number without introducing any new flavor structures, beyond those needed to account for the known fermion masses and mixings, is analyzed. With four generations, but only three colors, this minimality requirement is shown to lead to baryon number conservation, up to negligible dimension-18 operators. In a supersymmetric context, this same minimality principle allows only superpotential terms with an even number of flavored superfields, hence effectively enforces R-parity both within the MSSM and in a GUT context.
We study the effect from a sequential fourth generation quark on penguin-dominated two-body nonleptonic B meson decays in the next-to-leading order perturbative QCD formalism. With an enhancement of the color-suppressed tree amplitude and possibility of a new CP phase in the electroweak penguin, we can account better for A_{CP}(B^0 -> K^+ pi^-)-A_{CP}(B^+ -> K^+ pi^0). Taking |V_{t's}V_{t'b}| \sim 0.02 with phase just below 90^\circ, which are consistent with the b -> s l^+ l^- rate and the B_s mixing parameter Δm_{B_s}, we find a downward shift in the mixing-induced CP asymmetries of B^0 -> K…
We study extensions of the standard model with a strongly coupled fourth generation. This occurs in models where electroweak symmetry breaking is triggered by the condensation of at least some of the fourth-generation fermions. With focus on the phenomenology at the LHC, we study the pair production of fourth-generation down quarks, D4. We consider the typical masses that could be associated with a strongly coupled fermion sector, in the range (300--600) GeV. We show that the production and successive decay of these heavy quarks into final states with same-sign dileptons, trileptons and four l…
We analyze a recently proposed extension of the Standard Model based on the SU(4) x SU(2)_L x U(1)_X gauge group, in which baryon number is interpreted as the fourth color and dark matter emerges as a neutral partner of the ordinary quarks under SU(4). We show that under well-motivated minimal flavor-violating assumptions the particle spectrum contains a heavy dark matter candidate which is dominantly the partner of the right-handed top quark. Assuming a standard cosmology, the correct thermal relic density through freeze-out is obtained for dark matter masses around 2 - 3 TeV. We examine the …
We study the effect of a magnetic field on the pairing dynamics in two-flavor color superconducting dense quark matter. The study is performed in the weakly coupled regime of QCD at asymptotically high density, using the framework of the Schwinger-Dyson equation in the improved rainbow approximation. We show that the superconducting gap function develops a directional dependence in momentum space. Quasiparticles with momenta perpendicular to the direction of the magnetic field have the largest gaps, while quasiparticles with momenta parallel to the field have the smallest gaps. We argue that t…
Color charge correlations in the proton at moderately small $x\sim 0.1$ are extracted from its light-cone wave function. The charge fluctuations are far from Gaussian and they exhibit interesting dependence on impact parameter and on the relative transverse momentum (or distance) of the gluon probes. We provide initial conditions for small-$x$ Balitsky-Kovchegov evolution of the dipole scattering amplitude with impact parameter and $\hat r \cdot \hat b$ dependence, and with non-zero $C$-odd component due to three-gluon exchange. Lastly, we compute the (forward) Weizsaecker-Williams gluon distr…
We examine the possibility that a new strong interaction is accessible to the Tevatron and the LHC. In an effective theory approach, we consider a scenario with a new color-octet interaction with strong couplings to the top quark, as well as the presence of a strongly coupled fourth-generation which could be responsible for electroweak symmetry breaking. We apply several constraints, including the ones from flavor physics. We study the phenomenology of the resulting parameter space at the Tevatron, focusing on the the forward-backward asymmetry in top pair production, as well as in the product…
Extending the well-known $SU(3)_C \times SU(3)_L \times SU(3)_R$ model of quarks and leptons to include a fourth $SU(3)_N$ gauge factor, a new realization is obtained, different from leptonic color, which contains a lepton/dark symmetry with the help of an input $Z_4$ symmetry. It is seen to encompass a previous extension of the standard model to $SU(2)_N$ lepton symmetry.
As a tribute to Abdus Salam, I recall the initiation in 1972-73 of the idea of grand unification based on the view that lepton number is the fourth color. Motivated by aesthetic demands, these attempts led to the suggestion that the existing $SU(2)\times U(1)$ symmetry be extended minimally to the quark-lepton and left-right symmetric non-Abelian gauge structure $G(2,2,4) = SU(2)_L\times SU(2)_R\times SU(4)$-color. This unified members of a family within a single L-R self-conjugate multiplet. It also explained: the quantization of electric charge, the co-existence of quarks and leptons, and th…
We discuss a confining model for quark-antiquark system with a new color $SU_3$ gauge symmetry. New gauge transformations involve non-integrable phase factors and lead to the fourth-order gauge field equations and a linear potential. The massless gauge bosons have non-definite energies, which are not observable because they are permanently confined in quark systems by the linear potential. We use the empirical potentials of charmonium to determine the coupling strength of the color charge $g_s$ and find $g_s^2/(4π) \approx 0.2.$ We discuss Feynman-Dyson rules for the confining quark model, whi…
We present our study of bound states of the fourth generation quarks in the range of 500 to 700 GeV,where we expect binding energies are mainly of Yukawa origin, with QCD subdominant. Near degeneracy of their masses exhibits a new "isospin". We find the most interesting is the production of a color octet, isosinglet vector meson via $q\bar q \to ω_8$. Its leading decay modes are $π_8^\pm W^\mp$, $π_8^0Z^0$, and constituent quark decay, with $q\bar q$ and $t\bar t'$ and $b\bar b'$ subdominant. The color octet, isovector pseudoscalar $π_8$ meson decays via constituent quark decay, or to $Wg$. Th…
We apply Ginzburg-Landau theory to determine BCS pairing in a strongly-coupled uniform superfluid of three-flavor massless quarks in flavor equilibrium. We elucidate the phase diagram near the critical temperature in the space of the parameters characterizing the thermodynamic potential terms of fourth order in the pairing gap. Within the color and flavor antisymmetric channel with zero total angular momentum, the phase diagram contains an isoscalar (IS) color-antitriplet phase and a color-flavor-locked (CFL) phase, reached by a second order transition from the normal state, as well as states …
In the framework of the model motivated by perturbative calculations in the fourth $O(α^3_sα)$-order, the estimates for the $γp$ cross-section of the $D^*$-meson production in the ZEUS experiment are performed. We factorize the hadronization of $(c\bar q)$-state hardly produced in perturbative QCD, which allows us to take into account the higher twist terms in the powers of $1/p_T$ at $p_T\sim m_c$ and to correctly reproduce the c-quark fragmentation dominant at high $p_T\gg m_c$ to the given order of $α_s$. We find a good agreement with the experimental data on the photoproduction, if the col…
