pinecone/core-2020-05-10-deduplication huggingface dataset:
Living with ghosts in Horava-Lifshitz gravity

We consider the branch of the projectable Horava-Lifshitz model which
exhibits ghost instabilities in the low energy limit. It turns out that, due to
the Lorentz violating structure of the model and to the presence of a finite
strong coupling scale, the vacuum decay rate into photons is tiny in a wide
range of phenomenologically acceptable parameters. The strong coupling scale,
understood as a cutoff on ghosts' spatial momenta, can be raised up to $\Lambda
\sim 10$ TeV. At lower momenta, the projectable Horava-Lifshitz gravity is
equivalent to General Relativity supplemented by a fluid with a small positive
sound speed squared ($10^{-42}\lesssim$) $c^2_s \lesssim 10^{-20}$, that could
be a promising candidate for the Dark Matter. Despite these advantages, the
unavoidable presence of the strong coupling obscures the implementation of the
original Horava's proposal on quantum gravity. Apart from the Horava-Lifshitz
model, conclusions of the present work hold also for the mimetic matter
scenario, where the analogue of the projectability condition is achieved by a
non-invertible conformal transformation of the metric.Comment: 33 pages, 1 figure. The proof of an equivalence between the IR limit
  of the projectable Horava-Lifshitz gravity and the mimetic matter scenario is
  given in Appendix A. Version accepted for publication in JHE
D branes in background fluxes and Nielsen-Olesen instabilities

In quantum field theory, charged particles with spin $\geq 1$ may become
tachyonic in the present of magnetic fluxes above some critical field,
signaling an instability of the vacuum. The phenomenon is generic, in
particular, similar instabilities are known to exist in open and closed string
theory, where a spinning string state can become tachyonic above a critical
field. In compactifications involving RR fluxes $F_{p+2}$, the quantum states
which could become tachyonic by the same Nielsen-Olesen mechanism are Dp
branes. By constructing an appropriate background with RR magnetic flux that
takes into account back-reaction, we identify the possible tachyonic Dp brane
states and compute the formula for the energy spectrum in a sector. More
generally, we argue that in any background RR magnetic flux, there are high
spin Dp quantum states which become very light at critical fields.Comment: 14 pages. (V3 comments and references added.
The double copy: Bremsstrahlung and accelerating black holes

Advances in our understanding of perturbation theory suggest the existence of
a correspondence between classical general relativity and Yang-Mills theory. A
concrete example of this correspondence, which is known as the double copy, was
recently introduced for the case of stationary Kerr-Schild spacetimes. Building
on this foundation, we examine the simple time-dependent case of an
accelerating, radiating point source. The gravitational solution, which
generalises the Schwarzschild solution, includes a non-trivial stress-energy
tensor. This stress-energy tensor corresponds to a gauge theoretic current in
the double copy. We interpret both of these sources as representing the
radiative part of the field. Furthermore, in the simple example of
Bremsstrahlung, we determine a scattering amplitude describing the radiation,
maintaining the double copy throughout. Our results provide the strongest
evidence yet that the classical double copy is directly related to the BCJ
double copy for scattering amplitudes.Comment: 24 pages, 2 figure
Free-field realisations of the BMS$_3$ algebra and its extensions

We construct an explicit realisation of the BMS$_3$ algebra with nonzero
central charges using holomorphic free fields. This can be extended by the
addition of chiral matter to a realisation having arbitrary values for the two
independent central charges. Via the introduction of additional free fields, we
extend our construction to the minimally supersymmetric BMS$_3$ algebra and to
the nonlinear higher-spin BMS$_3$-W$_3$ algebra. We also describe an extended
system that realises both the SU(2) current algebra as well as BMS$_3$ via the
Wakimoto representation, though in this case introducing a central extension
also brings in new non-central operators.Comment: 1+18 pages, expanded version, new section on higher-spin
  BMS$_3$-W$_3$ added, JHEP Versio
Dual Double Field Theory

We present the dual formulation of double field theory at the linearized
level. This is a classically equivalent theory describing the duals of the
dilaton, the Kalb-Ramond field and the graviton in a T-duality or O(D,D)
covariant way. In agreement with previous proposals, the resulting theory
encodes fields in mixed Young-tableau representations, combining them into an
antisymmetric 4-tensor under O(D,D). In contrast to previous proposals, the
theory also requires an antisymmetric 2-tensor and a singlet, which are not all
pure gauge. The need for these additional fields is analogous to a similar
phenomenon for "exotic" dualizations, and we clarify this by comparing with the
dualizations of the component fields. We close with some speculative remarks on
the significance of these observations for the full non-linear theory yet to be
constructed.Comment: 38 pages, v2: refs. added, to appear in JHE
Off-shell single-top production at NLO matched to parton showers

We study the hadroproduction of a $Wb$ pair in association with a light jet,
focusing on the dominant $t$-channel contribution and including exactly at the
matrix-element level all non-resonant and off-shell effects induced by the
finite top-quark width. Our simulations are accurate to the next-to-leading
order in QCD, and are matched to the HERWIG6 and PYTHIA8 parton showers through
the MC@NLO method. We present phenomenological results relevant to the 8 TeV
LHC, and carry out a thorough comparison to the case of on-shell $t$-channel
single-top production. We formulate our approach so that it can be applied to
the general case of matrix elements that feature coloured intermediate
resonances and are matched to parton showers.Comment: 36 pages, 7 figure
Rigid Supersymmetric Backgrounds of 3-dimensional Newton-Cartan
  Supergravity

Recently, a non-relativistic off-shell formulation of three dimensional
Newton-Cartan supergravity was proposed as the $c \rightarrow \infty$ limit of
three dimensional $\mathcal{N}=2$ supergravity in arXiv:1505.02095. In the
present paper we study supersymmetric backgrounds within this theory. Using
integrability constraints for the non-relativistic Killing spinor equations, we
explicitly construct all maximally supersymmetric solutions, which admit four
supercharges. In addition to these solutions, there are $\frac{1}{2}$-BPS
solutions with reduced supersymmetry. We give explicit examples of such
backgrounds and derive necessary conditions for backgrounds preserving two
supercharges. Finally, we address how supersymmetric backgrounds of
$\mathcal{N}=2$ supergravity are connected to the solutions found here in the
$c \rightarrow \infty$ limit.Comment: 26 pages + 2 appendices, 2 figures; v2: references added, clarified
  which N=2 supergravity theory is being considered; v3: reference added; added
  clarification and explicit solutions to relativistic integrability condition
Baryon as Impurity for Phase Transition in String Landscape

We consider a decay of a false vacuum in flux compactifications of type IIB
string theory and study a catalytic effect for a phase transition induced by a
new type of impurities. We concentrate on the large N dual of a
D5-brane/anti-D5-brane system which has a rich vacuum structure. We show that
D3-branes wrapping the 3-cycles can form a dibaryon and make a bound state with
a monopole. We find that these baryon-like objects can make the lifetime of the
metastable vacuum shorter.Comment: 22 pages, 13 figure
Flux tubes at finite temperature

The chromoelectric field generated by a static quark-antiquark pair, with its
peculiar tube-like shape, can be nicely described, at zero temperature, within
the dual superconductor scenario for the QCD confining vacuum. In this work we
investigate, by lattice Monte Carlo simulations of the SU(3) pure gauge theory,
the fate of chromoelectric flux tubes across the deconfinement transition. We
find that, as the temperature is increased towards and above the deconfinement
temperature $T_c$, the amplitude of the field inside the flux tube gets
smaller, while the shape of the flux tube does not vary appreciably across
deconfinement. This scenario with flux-tube "evaporation" above $T_c$ has no
correspondence in ordinary (type-II) superconductivity, where instead the
transition to the phase with normal conductivity is characterized by a
divergent fattening of flux tubes as the transition temperature is approached
from below. We present also some evidence about the existence of flux-tube
structures in the magnetic sector of the theory in the deconfined phase.Comment: arXiv admin note: text overlap with arXiv:1404.117
Singlet Extensions of the Standard Model at LHC Run 2: Benchmarks and
  Comparison with the NMSSM

The Complex singlet extension of the Standard Model (CxSM) is the simplest
extension that provides scenarios for Higgs pair production with different
masses. The model has two interesting phases: the dark matter phase, with a
Standard Model-like Higgs boson, a new scalar and a dark matter candidate; and
the broken phase, with all three neutral scalars mixing. In the latter phase
Higgs decays into a pair of two different Higgs bosons are possible. In this
study we analyse Higgs-to-Higgs decays in the framework of singlet extensions
of the Standard Model (SM), with focus on the CxSM. After demonstrating that
scenarios with large rates for such chain decays are possible we perform a
comparison between the NMSSM and the CxSM. We find that, based on
Higgs-to-Higgs decays, the only possibility to distinguish the two models at
the LHC run 2 is through final states with two different scalars. This
conclusion builds a strong case for searches for final states with two
different scalars at the LHC run 2. Finally, we propose a set of benchmark
points for the real and complex singlet extensions to be tested at the LHC run
2. They have been chosen such that the discovery prospects of the involved
scalars are maximised and they fulfil the dark matter constraints. Furthermore,
for some of the points the theory is stable up to high energy scales. For the
computation of the decay widths and branching ratios we developed the Fortran
code, sHDECAY, which is based on the implementation of the real and complex
singlet extensions of the SM in HDECAY.Comment: 49 pages, 6 figures. Improved text, updated samples and figures.
  Conclusions unchanged. To appear in JHE
Quantum Spectral Curve and the Numerical Solution of the Spectral
  Problem in AdS5/CFT4

We developed an efficient numerical algorithm for computing the spectrum of
anomalous dimensions of the planar ${\cal N}=4$ Super-Yang--Mills at finite
coupling. The method is based on the Quantum Spectral Curve formalism. In
contrast to Thermodynamic Bethe Ansatz, worked out only for some very special
operators, this method is applicable for generic states/operators and is much
faster and precise due to its Q-quadratic convergence rate.
  To demonstrate the method we evaluate the dimensions $\Delta$ of twist
operators in $sl(2)$ sector directly for any value of the spin $S$ including
non-integer values. In particular, we compute the BFKL pomeron intercept in a
wide range of the 't Hooft coupling constant with up to $20$ significant
figures precision, confirming two previously known from the perturbation theory
orders and giving prediction for several new coefficients. Furthermore, we
explore numerically a rich branch cut structure for complexified spin $S$.Comment: 24 pages, 7 figures; v2: updated data, added strong coupling fits,
  improvements of the algorithm described in section 3.4; v3: added Mathematica
  notebook with implementation of the algorithm, minor corrections in the tex
The minimal linear sigma model for the Goldstone Higgs

In the context of the minimal SO(5) linear {\sigma}-model, a complete
renormalizable Lagrangian -including gauge bosons and fermions- is considered,
with the symmetry softly broken to SO(4). The scalar sector describes both the
electroweak Higgs doublet and the singlet {\sigma}. Varying the {\sigma} mass
would allow to sweep from the regime of perturbative ultraviolet completion to
the non-linear one assumed in models in which the Higgs particle is a
low-energy remnant of some strong dynamics. We analyze the phenomenological
implications and constraints from precision observables and LHC data.
Furthermore, we derive the d <= 6 effective Lagrangian in the limit of heavy
exotic fermions
Electroproduction of tensor mesons in QCD

Due to multiple possible polarizations hard exclusive production of tensor
mesons by virtual photons or in heavy meson decays offers interesting
possibilities to study the helicity structure of the underlying short-distance
process. Motivated by the first measurement of the transition form factor
$\gamma^*\gamma \to f_2(1270)$ at large momentum transfers by the BELLE
collaboration we present an improved QCD analysis of this reaction in the
framework of collinear factorization including contributions of twist-three
quark-antiquark-gluon operators and an estimate of soft end-point corrections
using light-cone sum rules. The results appear to be in a very good agreement
with the data, in particular the predicted scaling behavior is reproduced in
all cases.Comment: 27 pages, 5 figure
Direct Neutrino Mass Experiments and Exotic Charged Current Interactions

We study the effect of exotic charged current interactions on the electron
energy spectrum in tritium decay, focussing on the KATRIN experiment and a
possible modified setup that has access to the full spectrum. Both sub-eV and
keV neutrino masses are considered. We perform a fully relativistic calculation
and take all possible new interactions into account, demonstrating the possible
sizable distortions in the energy spectrum.Comment: 38 pages, 6 figures, no diphotons. Comments and references adde
The string-junction picture of multiquark states: an update

We recall and update, both theoretically and phenomenologically, our (nearly)
forty-years-old proposal of a string-junction as a necessary complement to the
conventional classification of hadrons based just on their quark-antiquark
constituents. In that proposal single (though in general metastable) hadronic
states are associated with "irreducible" gauge-invariant operators consisting
of Wilson lines (visualized as strings of color flux tubes) that may either end
on a quark or an antiquark, or annihilate in triplets at a junction $J$ or an
anti-junction $\bar{J}$. For the junction-free sector (ordinary $q\, \bar{q}$
mesons and glueballs) the picture is supported by large-$N$ (number of colors)
considerations as well as by a lattice strong-coupling expansion. Both imply
the famous OZI rule suppressing quark-antiquark annihilation diagrams. For
hadrons with $J$ and/or $\bar{J}$ constituents the same expansions support our
proposal, including its generalization of the OZI rule to the suppression of
$J-\bar{J}$ annihilation diagrams. Such a rule implies that hadrons with
junctions are "mesophobic" and thus unusually narrow if they are below
threshold for decaying into as many baryons as their total number of junctions
(two for a tetraquark, three for a pentaquark). Experimental support for our
claim, based on the observation that narrow multiquark states typically lie
below (well above) the relevant baryonic (mesonic) thresholds, will be
presented.Comment: 37 pages, 18 figures Some clarifications and several new references
  adde
Diphoton and Diboson Probes of Fermiophobic Higgs Bosons at the LHC

Extensions of the Standard Model Higgs sector with electroweak charged
scalars can possess exotic `Higgs' bosons with vanishing or suppressed
couplings to Standard Model fermions. These `fermiophobic' scalars, which
cannot be produced via gluon fusion, are constrained by LHC measurements of the
125 GeV Higgs boson to have a small vacuum expectation value. This implies that
vector boson fusion and associated vector boson production are in general
suppressed rendering conventional Higgs searches insensitive. However,
Drell-Yan Higgs pair production, which is not present in the SM, can be
sizeable even in the limit of vanishing exotic Higgs vacuum expectation value.
We utilize this to show that diphoton searches at 8 TeV LHC already rule out a
large class of neutral fermiophobic Higgs bosons below around 110 GeV. This
includes fermiophobic scalars found in two Higgs doublet as well as Higgs
triplet and Georgi-Machacek type models. Our results extend the only relevant
limit on fermiophobic Higgs bosons obtained by a recent CDF analysis of
$4\gamma + X$ Tevatron data. Furthermore, diphoton limits are independent of
the decay of the second Higgs boson and thus apply even for degenerate masses
in contrast to the CDF search. We also find that if the fermiophobic Higgs has
very enhanced couplings to photons, masses as large as $\sim 150$ GeV can be
ruled out while if these couplings are somehow highly suppressed, masses below
$\sim 90$ GeV can still be ruled out. Finally, we show that $WW$ and $ZZ$
diboson searches may serve as complementary probes for masses above the
diphoton limit up to $\sim 250$ GeV and discuss prospects at 13 TeV LHC.Comment: references and small comments adde
The Optical Potential on the Lattice

The extraction of hadron-hadron scattering parameters from lattice data by
using the L\"uscher approach becomes increasingly complicated in the presence
of inelastic channels. We propose a method for the direct extraction of the
complex hadron-hadron optical potential on the lattice, which does not require
the use of the multi-channel L\"uscher formalism. Moreover, this method is
applicable without modifications if some inelastic channels contain three or
more particles.Comment: 26 pages, 12 figure
S-folds and 4d N=3 superconformal field theories

S-folds are generalizations of orientifolds in type IIB string theory, such
that the geometric identifications are accompanied by non-trivial S-duality
transformations. They were recently used by Garcia-Etxebarria and Regalado to
provide the first construction of four dimensional N=3 superconformal theories.
In this note, we classify the different variants of these N=3 preserving
S-folds, distinguished by an analog of discrete torsion, using both a direct
analysis of the different torsion classes and the compactification of the
S-folds to three dimensional M-theory backgrounds. Upon adding D3-branes, these
variants lead to different classes of N=3 superconformal field theories. We
also analyze the holographic duals of these theories, and in particular clarify
the role of discrete gauge and global symmetries in holography.Comment: 29 pages; v2: references adde
Supersymmetric geometries of IIA supergravity III

We find that (massive) IIA backgrounds that admit a $G_2\ltimes \mathbb{R}^8$
invariant Killing spinor must exhibit a null Killing vector field which leaves
the Killing spinor invariant and that the rotation of the Killing vector field
satisfies a certain $\mathfrak{g}_2$ instanton condition. This result together
with those in [4] and [5] complete the classification of geometries of all
(massive) IIA backgrounds that preserve one supersymmetry. We also explore the
geometry of a class of backgrounds which admit a $G_2\ltimes \mathbb{R}^8$
invariant Killing spinor and where in addition an appropriate 1-form bilinear
vanishes. In all cases, we express the fluxes of the theory in terms of the
geometry.Comment: 27 page
A Practical Approach to the Hamilton-Jacobi Formulation of Holographic
  Renormalization

We revisit the subject of holographic renormalization for asymptotically AdS
spacetimes. For many applications of holography, one has to handle the
divergences associated with the on-shell gravitational action. The brute force
approach uses the Fefferman-Graham (FG) expansion near the AdS boundary to
identify the divergences, but subsequent reversal of the expansion is needed to
construct the infinite counterterms. While in principle straightforward, the
method is cumbersome and application/reversal of FG is formally unsatisfactory.
Various authors have proposed an alternative method based on the
Hamilton-Jacobi equation. However, this approach may appear to be abstract,
difficult to implement, and in some cases limited in applicability. In this
paper, we clarify the Hamilton-Jacobi formulation of holographic
renormalization and present a simple algorithm for its implementation to
extract cleanly the infinite counterterms. While the derivation of the method
relies on the Hamiltonian formulation of general relativity, the actual
application of our algorithm does not. The work applies to any $D$-dimensional
holographic dual with asymptotic AdS boundary, Euclidean or Lorentzian, and
arbitrary slicing. We illustrate the method in several examples, including the
FGPW model, a holographic model of 3d ABJM theory, and cases with marginal
scalars such as a dilaton-axion system.Comment: 20 pages + appendices, no figures. v2: References added. v3: Typos
  corrected, references update
Quasinormal modes and the phase structure of strongly coupled matter

We investigate the poles of the retarded Green's functions of strongly
coupled field theories exhibiting a variety of phase structures from a
crossover up to different first order phase transitions. These theories are
modeled by a dual gravitational description. The poles of the holographic
Green's functions appear at the frequencies of the quasinormal modes of the
dual black hole background. We focus on quantifying linearized level dynamical
response of the system in the critical region of phase diagram. Generically
non-hydrodynamic degrees of freedom are important for the low energy physics in
the vicinity of a phase transition. For a model with linear confinement in the
meson spectrum we find degeneracy of hydrodynamic and non-hydrodynamic modes
close to the minimal black hole temperature, and we establish a region of
temperatures with unstable non-hydrodynamic modes in a branch of black hole
solutions.Comment: 33 pages, 14 figure
Probing CP violation in $e^{+}e^{-}$ production of the Higgs boson and
  toponia

We study the CP violation in the Higgs boson and toponia production process
at the ILC where the toponia are produced near the threshold. With the
approximation that the production vertex of the Higgs boson and toponia is
contact, and neglecting the P-wave toponia, we analytically calculated the
density matrix for the production and decay of the toponia. Under these
assumptions, the production spectrum of the toponia is solely determined by the
spin quantum number, therefore the toponia can be either singlet or triplet. We
find that the production rate of the singlet toponium is highly suppressed, and
behaves just like the production of a P-wave toponia. In the case of the
triplet toponium, three completely independent CP observables, namely azimuthal
angles of lepton and anti-lepton in the toponium rest-frame as well as their
sum, are predicted based on our analytical results, and checked by using the
tree-level event generator. The non-trivial correlations come from the
longitudinal-transverse interferences for the azimuthal angles of leptons, and
the transverse-transverse interference for their sum. These three observables
are well defined at the ILC, where the rest frame of the toponium can be
reconstructed directly. Furthermore, the QCD-strong corrections, which are
important near the threshold region, are also studied with the approximation of
spin-independent QCD-Coulomb potential. While the total cross section is
enhanced, the spin correlations predicted in this paper are not affected.Comment: 32pages, 18figures, KEK-TH-1877. Accepted version by JHE