相关论文: Gauged Baryon and Lepton Number in MSSM_4 Brane Wo…
I briefly describe the recent construction of the first specific string D-brane models yielding just the SM massless fermion spectrum. One of the most remarkable facts predicted by these constructions is that the global symmetries of the SM…
We perform a systematic study of the Standard Model embedding in a D-brane configuration of type I string theory at the TeV scale. We end up with an attractive model and we study several phenomenological questions, such as gauge coupling…
Models where the baryon (B) and lepton (L) numbers are local gauge symmetries that are spontaneously broken at a low scale are revisited. We find new extensions of the Standard Model which predict the existence of fermions that carry both…
We present what we believe are the first specific string (D-brane) constructions whose low-energy limit yields just a three generation $SU(3)\times SU(2)\times U(1)$ standard model with no extra fermions nor U(1)'s (without any further…
We investigate the spontaneous breaking of the Baryon (B) and Lepton (L) number at the TeV scale in supersymmetric models. A simple extension of the minimal supersymmetric standard model where B and L are spontaneously broken local gauge…
A new nontrivial U(1) gauge extension of the Minimal Supersymmetric Standard Model (MSSM) is proposed which automatically conserves baryon number and lepton number, and solves the mu problem. Naturally small Dirac neutrino masses are also…
Generic D-brane string models of particle physics predict the existence of extra U(1) gauge symmetries beyond hypercharge. These symmetries are not of the E_6 class but rather include the gauging of Baryon and Lepton numbers as well as…
A simple extension of the minimal supersymmetric standard model in which baryon and lepton numbers are local gauge symmetries spontaneously broken at the supersymmetry scale is reported. This theory provides a natural explanation for proton…
A simple theory where the total lepton number is a local gauge symmetry is proposed. In this context, the gauge anomalies are cancelled with the minimal number of extra fermionic fields and one predicts that the neutrinos are Majorana…
We argue that simpler fermionic contents, responsible for the extension of the standard model with gauged lepton and baryon charges, can be constructed by assuming existence of so-called leptoquarks (j,k) with exotic electric charges…
A new scenario for baryogenesis is described. The basic idea is that theories beyond the standard model which contain a ${\rm U}(1)_{B-L}$ gauge symmetry, where $B$ and $L$ are respectively baryon and lepton numbers, predict the existence…
We perform a detailed analysis of baryon asymmetry generation in the NuMSM (an extension of the Standard Model by three singlet Majorana fermions with masses below the Fermi scale). Fixing a number of parameters of the NuMSM by the neutrino…
We investigate a simple theory where Baryon number (B) and Lepton number (L) are local gauge symmetries. In this theory B and L are on the same footing and the anomalies are cancelled by adding a single new fermionic generation. There is an…
We show that under a new U(1) gauge symmetry, which is non-anomalous in the presence of one ``right-handed neutrino'' per generation and consistent with the standard model Yukawa couplings, the most general fermion charges are determined in…
A scenario for the generation of the baryon asymmetry in the early Universe is proposed in which cosmic string loops, predicted by theories where the baryon and/or lepton numbers are gauged symmetries, collapse during the friction dominated…
In the canonical seesaw mechanism of neutrino mass, lepton number is only multiplicatively conserved, which enables the important phenomenon of leptogenesis to occur, as an attractive explanation of the present baryon asymmetry of the…
We consider a 5D SUSY $SU(3)_c\times SU(2)_L\times U(1)_Y\times {\cal U}(1)$ model compactified on an $S^{(1)}/Z_2$ orbifold. To cancel anomalies arising from the presence of ${\cal U}(1)$, we employ a Chern-Simons term and also chiral…
We study D-brane inspired models with U(3) x U(2) x U(1)^N gauge symmetry in the context of split supersymmetry. We consider configurations with one, two and three (N=1,2,3) abelian branes and derive all hypercharge embeddings which imply a…
We explore the spontaneous breaking of global baryon number for baryogenesis. We introduce a model with three majorana fermions and a complex scalar carrying baryon number charge. After symmetry breaking, the baryon asymmetry is generated…
A fourth generation of Standard Model (SM) fermions is usually considered unlikely due to constraints from direct searches, electroweak precision measurements, and perturbative unitarity. We show that fermion mass textures consistent with…