1,804 research outputs found

### Simple Scheme for Gauge Mediation

We present a simple scheme for constructing models that achieve successful
gauge mediation of supersymmetry breaking. In addition to our previous work [1]
that proposed drastically simplified models using metastable vacua of
supersymmetry breaking in vector-like theories, we show there are many other
successful models using various types of supersymmetry breaking mechanisms that
rely on enhanced low-energy U(1)_R symmetries. In models where supersymmetry is
broken by elementary singlets, one needs to assume U(1)_R violating effects are
accidentally small, while in models where composite fields break supersymmetry,
emergence of approximate low-energy U(1)_R symmetries can be understood simply
on dimensional grounds. Even though the scheme still requires somewhat small
parameters to sufficiently suppress gravity mediation, we discuss their
possible origins due to dimensional transmutation. The scheme accommodates a
wide range of the gravitino mass to avoid cosmological problems.Comment: 13 page

### Non(anti)commutative superspace with coordinate-dependent deformation

We consider non(anti)commutative superspace with coordinate dependent
deformation parameters $C^{\alpha\beta}$. We show that a chiral ${\cal N}=1/2$
supersymmetry can be defined and that chiral and antichiral superfields are
still closed under the Moyal-Weyl associative product implementing the
deformation. A consistent ${\cal N}=1/2$ Super Yang-Mills deformed theory can
be constructed provided $C^{\alpha\beta}$ satisfies a suitable condition which
can be connected with the graviphoton background at the origin of the
deformation. After adding matter we also discuss the Konishi anomaly and the
gluino condensation.Comment: References added. Accepted for publication in PR

### Composition of primary cosmic rays at energies 10(15) to approximately 10(16) eV

The sigma epsilon gamma spectrum in 1 approx. 5 x 1000 TV observed at Mt. Fuji suggests that the flux of primary protons 10 to the 15 approx 10th eV is lower by a factor of 2 approx. 3 than a simple extrapolation from lower energies; the integral proton spectrum tends to be steeper than around to the power V and the spectral index tends to be steeper than Epsilon to the -17th power around 10 to the 14th power eV and the spectral index becomes approx. 2.0 around 10 to the 15th power eV. If the total flux of primary particles has no steepening up to approx 10 to the 15th power eV, than the fraction of primary protons to the total flux should be approx 20% in contrast to approx 45% at lower energies

### World-sheet Stability of (0,2) Linear Sigma Models

We argue that two-dimensional (0,2) gauged linear sigma models are not
destabilized by instanton generated world-sheet superpotentials. We construct
several examples where we show this to be true. The general proof is based on
the Konishi anomaly for (0,2) theories.Comment: 18 pages, LaTe

### Complex BPS domain walls and phase transition in mass in supersymmetric QCD

We study the domain walls connecting different chirally asymmetric vacua in
supersymmetric QCD. We show that BPS - saturated solutions exist only in the
limited range of mass. When m exceeds some critical value, the domain wall
either ceases to be BPS - saturated or disappears altogether. In any case, the
properties of the system are qualitatively changed.Comment: 10 pages LaTeX, 4 Postscript figures. References adde

### On Mass Spectrum in SQCD, and Problems with the Seiberg Duality. Equal quark masses

The dynamical scenario is considered for N=1 SQCD, with N_c colors and
N_c<N_F<3N_c flavors with small but nonzero current quark masses m_Q\neq 0, in
which quarks form the diquark-condensate phase. This means that colorless
chiral quark pairs condense coherently in the vacuum, \neq 0, while
quarks alone don't condense, ==0, so that the color is confined.
Such condensation of quarks results in formation of dynamical constituent
masses \mu_C \gg m_Q of quarks and appearance of light "pions" (similarly to
QCD). The mass spectrum of SQCD in this phase is described and comparison with
the Seiberg dual description is performed. It is shown that the direct and dual
theories are different (except, possibly, for the perturbative strictly
superconformal regime).Comment: 31 pages; text improved; corrections in sections 5,8; appendix added
about 't Hooft triangle

### Gravitino condensation in fivebrane backgrounds

We calculate the tension of the D3-brane in the fivebrane background which is
described by the exactly solvable SU(2)_k x U(1) world-sheet conformal field
theory with large Kac-Moody level k. The D3-brane tension is extracted from the
amplitude of one closed string exchange between two parallel D3-branes, and the
amplitude is calculated by utilizing the open-closed string duality. The
tension of the D3-brane in the background does not coincide with the one in the
flat space-time even in the flat space-time limit: k -> infinity. The finite
curvature effect should vanish in the flat space-time limit and only the
topological effect can remain. Therefore, the deviation indicates the
condensation of gravitino and/or dilatino which has been expected in the
fivebrane background as a gravitational instanton.Comment: 16 pages, 1 figur

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