3,091 research outputs found
Decays of metastable vacua in SQCD
The decay rates of metastable SQCD vacua in ISS-type models, both towards
supersymmetric vacua as well as towards other nonsupersymmetric configurations
arising in theories with elementary spectators, are estimated numerically in
the semiclassical approximation by computing the corresponding multifield
bounce configurations. The scaling of the bounce action with respect to the
most relevant dimensionless couplings and ratios of scales is analyzed. In the
case of the decays towards the susy vacua generated by nonperturbative effects,
the results confirm previous analytical estimations of this scaling, obtained
by assuming a triangular potential barrier. The decay rates towards susy vacua
generated by R-symmetry breaking interactions turn out to be more than
sufficiently suppressed for the phenomenologically relevant parameter range,
and their behavior in this regime differs from analytic estimations valid for
parametrically small scale ratios. It is also shown that in models with
spectator fields, even though the decays towards vacua involving nonzero
spectator VEVs don't have a strong parametric dependence on the scale ratios,
the ISS vacuum can still be made long-lived in the presence of R-symmetry
breaking interactions.Comment: 22 pages, 7 figure
NNMSM Type-II and III
We suggest two types of extension of the standard model, which are the
so-called next to new minimal standard model (NNMSM) type-II and -III. They can
achieve gauge coupling unification as well as suitable dark matter abundance,
small neutrino masses, baryon asymmetry of the universe, inflation, and dark
energy. The gauge coupling unification can be realized by introducing extra two
or three new fields, and could explain the charge quantization. We also show
that there are regions in which the vacuum stability, coupling perturbativity,
and correct dark matter abundance can be realized with current experimental
data at the same time.Comment: 20 pages, 5 figures, comments added. arXiv admin note: substantial
text overlap with arXiv:1309.123
Flux Discharge Cascades in Various Dimensions
We study the dynamics of electric flux discharge by charged particle pair or
spherical string or membrane production in various dimensions. When electric
flux wraps at least one compact cycle, we find that a single "pair" production
event can initiate a cascading decay in real time that "shorts out" the flux
and discharges many units of it. This process arises from local dynamics in the
compact space, and so is invisible in the dimensionally-reduced truncation. It
occurs in theories as simple as the Schwinger model on a circle, and has
implications for any theory with compact dimensions and electric flux,
including string theories and the string landscape.Comment: 19+8 pages, 3 figures, 3 appendice
Probing Quantum Geometry at LHC
We present an evidence, that the volumes of compactified spaces as well as
the areas of black hole horizons must be quantized in Planck units. This
quantization has phenomenological consequences, most dramatic being for micro
black holes in the theories with TeV scale gravity that can be produced at LHC.
We predict that black holes come in form of a discrete tower with well defined
spacing. Instead of thermal evaporation, they decay through the sequence of
spontaneous particle emissions, with each transition reducing the horizon area
by strictly integer number of Planck units. Quantization of the horizons can be
a crucial missing link by which the notion of the minimal length in gravity
eliminates physical singularities. In case when the remnants of the black holes
with the minimal possible area and mass of order few TeV are stable, they might
be good candidates for the cold dark matter in the Universe.Comment: 14 pages, Late
A Comparative Note on Tunneling in AdS and in its Boundary Matrix Dual
For charged black hole, within the grand canonical ensemble, the decay rate
from thermal AdS to the black hole at a fixed high temperature increases with
the chemical potential. We check that this feature is well captured by a
phenomenological matrix model expected to describe its strongly coupled dual.
This comparison is made by explicitly constructing the kink and bounce
solutions around the de-confinement transition and evaluating the matrix model
effective potential on the solutions.Comment: 1+12 pages, 9 figure
The quantum mechanics of perfect fluids
We consider the canonical quantization of an ordinary fluid. The resulting
long-distance effective field theory is derivatively coupled, and therefore
strongly coupled in the UV. The system however exhibits a number of
peculiarities, associated with the vortex degrees of freedom. On the one hand,
these have formally a vanishing strong-coupling energy scale, thus suggesting
that the effective theory's regime of validity is vanishingly narrow. On the
other hand, we prove an analog of Coleman's theorem, whereby the semiclassical
vacuum has no quantum counterpart, thus suggesting that the vortex premature
strong-coupling phenomenon stems from a bad identification of the ground state
and of the perturbative degrees of freedom. Finally, vortices break the usual
connection between short distances and high energies, thus potentially
impairing the unitarity of the effective theory.Comment: 35 page
Poincar\'e Invariant Quantum Field Theories With Twisted Internal Symmetries
Following up the work of [1] on deformed algebras, we present a class of
Poincar\'e invariant quantum field theories with particles having deformed
internal symmetries. The twisted quantum fields discussed in this work satisfy
commutation relations different from the usual bosonic/fermionic commutation
relations. Such twisted fields by construction are nonlocal in nature. Despite
this nonlocality we show that it is possible to construct local interaction
Hamiltonians which satisfy cluster decomposition principle and are Lorentz
invariant. We further illustrate these ideas by considering global SU(N)
symmetries. Specifically we show that twisted internal symmetries can
significantly simplify the discussion of the marginal deformations
(\beta-deformations) of the N=4 SUSY theories.Comment: 27 pages, Typos Corrected, Text and Conclusions Unchanged, Version
published in JHE
Follow-up practices for high-grade extremity Osteosarcoma
BACKGROUND: The optimal conduct of follow-up (FU) of patients with osteosarcoma is uncertain. In the absence of any formal validation of optimal timing and method of surveillance, guidance is provided by oncology societies' recommendations. FU is designed to detect either local recurrence or metastatic disease at a time when early treatment is still possible and might be effective. METHODS: We performed a retrospective analysis of 101 patients with high-grade extremity osteosarcoma in a single centre. Chest x-ray (CXR) was used as routine surveillance method; however patients with initial lung metastases or previous suspicious findings had computed tomography (CT) scans. RESULTS: With a median FU time of 30.7 months 34 patients relapsed. Relapse-free survival after 5 years was 61% (CI 52%; 73%), late relapses occurred in only two patients between 2 and 5 years of FU. Twenty-five of the 34 relapses were detected at routine FU appointments. All 8 local recurrences were noted clinically. Twenty-two patients had metastases confined to the lungs, either detected on CXR or CT. Thirty-two percent of patients with lung metastases only were salvaged successfully. CONCLUSIONS: Routine FU in high-grade osteosarcoma results in clinical detection of local relapse, and detection of lung metastases by CXR at a time when metastatectomy is possible. The optimal time interval for FU appointments is not known, however we recommend more frequent surveillance visits during the two years after treatment. We hypothesize that routine CT scans are not required and propose CXR for detection of lung metastases
Supersymmetry breaking induced by radiative corrections
We show that simultaneous gauge and supersymmetry breaking can be induced by
radiative corrections, a la Coleman-Weinberg. When a certain correlation among
the superpotential parameters is present, a local supersymmetry-breaking
minimum is found in the effective potential of a gauge non-singlet field, in a
region where the tree-level potential is almost flat. Supersymmetry breaking is
then transmitted to the MSSM through gauge and chiral messenger loops, thus
avoiding the suppression of gaugino masses characteristic of direct gauge
mediation models. The use of a single field ensures that no dangerous tachyonic
scalar masses are generated at the one-loop level. We illustrate this mechanism
with an explicit example based on an SU(5) model with a single adjoint. An
interesting feature of the scenario is that the GUT scale is increased with
respect to standard unification, thus allowing for a larger colour Higgs
triplet mass, as preferred by the experimental lower bound on the proton
lifetime.Comment: 22 pages, 3 figures. Two references added, small redactional changes,
some discussion improved. Results unchange
Derrick's theorem beyond a potential
Scalar field theories with derivative interactions are known to possess
solitonic excitations, but such solitons are generally unsatisfactory because
the effective theory fails precisely where nonlinearities responsible for the
solitons are important. A new class of theories possessing (internal) galilean
invariance can in principle bypass this difficulty. Here, we show that these
galileon theories do not possess stable solitonic solutions. As a by-product,
we show that no stable solitons exist for a different class of derivatively
coupled theories, describing for instance the infrared dynamics of superfluids,
fluids, solids and some k-essence models.Comment: 4 page
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