pinecone/core-2020-05-10-deduplication huggingface dataset:
One-loop amplitudes on the Riemann sphere

The scattering equations provide a powerful framework for the study of
scattering amplitudes in a variety of theories. Their derivation from
ambitwistor string theory led to proposals for formulae at one loop on a torus
for 10 dimensional supergravity, and we recently showed how these can be
reduced to the Riemann sphere and checked in simple cases. We also proposed
analogous formulae for other theories including maximal super-Yang-Mills theory
and supergravity in other dimensions at one loop. We give further details of
these results and extend them in two directions. Firstly, we propose new
formulae for the one-loop integrands of Yang-Mills theory and gravity in the
absence of supersymmetry. These follow from the identification of the states
running in the loop as expressed in the ambitwistor-string correlator.
Secondly, we give a systematic proof of the non-supersymmetric formulae using
the worldsheet factorisation properties of the nodal Riemann sphere underlying
the scattering equations at one loop. Our formulae have the same decomposition
under the recently introduced Q-cuts as one-loop integrands and hence give the
correct amplitudes.Comment: 49 pages + appendices, 3 figures. v2: further comments on singular
  solutions. v3: improved factorisation section, published versio
Trace Anomaly and Counterterms in Designer Gravity

We construct concrete counterterms of the Balasubramanian-Kraus type for
Einstein-scalar theories with designer gravity boundary conditions in
AdS$_{4}$, so that the total action is finite on-shell and satisfy a well
defined variational principle for an arbitrary scalar field potential. We focus
on scalar fields with the conformal mass, $m^{2}=-2l^{-2}$, and show that the
holographic mass matches the Hamiltonian mass for any boundary conditions. We
compute the trace anomaly of the dual field theory in the generic case, as well
as when there exist logarithmic branches of non-linear origin. As expected, the
anomaly vanishes for the boundary conditions that are AdS invariant. When the
anomaly does not vanish, the dual stress tensor describes a thermal gas with an
equation of state related to the boundary conditions of the scalar field. When
the anomaly vanishes, we recover the dual theory of a massless thermal gas. As
an application of the formalism, we consider a general family of exact hairy
black hole solutions that, for some particular values of the parameters in the
moduli potential, contains solutions of four-dimensional gauged $\mathcal{N}=8$
supergravity and its $\omega$-deformation. Using the AdS/CFT duality
dictionary, they correspond to triple trace deformations of the dual field
theory.Comment: 26 pages, no figures v2: title changed, refs. added, matches the
  published versio
Irregular conformal block, spectral curve and flow equations

Irregular conformal block is motivated by the Argyres-Douglas type of N=2
super conformal gauge theory. We investigate the classical/NS limit of the
irregular conformal block using spectral curve on a Riemann surface with
irregular punctures, which is equivalent to the loop equation of irregular
matrix model. The spectral curve is reduced to the second order (Virasoro
symmetry, $SU(2)$ for the gauge theory) and third order ($W_3$ symmetry,
$SU(3)$) differential equations of a polynomial with finite degree. The
Virasoro and W symmetry generate flow equations in the spectral curve and
determine the irregular conformal block, hence the partition function of the
Argyres-Douglas theory ala AGT conjecture.Comment: 35 pages; v2: 38 pages, section 4 and references added, minor change
Relic density of wino-like dark matter in the MSSM

The relic density of TeV-scale wino-like neutralino dark matter in the MSSM
is subject to potentially large corrections as a result of the Sommerfeld
effect. A recently developed framework enables us to calculate the
Sommerfeld-enhanced relic density in general MSSM scenarios, properly treating
mixed states and multiple co-annihilating channels as well as including
off-diagonal contributions. Using this framework, including on-shell one-loop
mass splittings and running couplings and taking into account the latest
experimental constraints, we perform a thorough study of the regions of
parameter space surrounding the well known pure-wino scenario: namely the
effect of sfermion masses being non-decoupled and of allowing non-negligible
Higgsino or bino components in the lightest neutralino. We further perform an
investigation into the effect of thermal corrections and show that these can
safely be neglected. The results reveal a number of phenomenologically
interesting but so far unexplored regions where the Sommerfeld effect is
sizeable. We find, in particular, that the relic density can agree with
experiment for dominantly wino neutralino dark matter with masses ranging from
1.7 to beyond 4 TeV. In light of these results the bounds from Indirect
Detection on wino-like dark matter should be revisited.Comment: 49 pages, 15 figure
Bootstrapping 3D Fermions

We study the conformal bootstrap for a 4-point function of fermions
$\langle\psi\psi\psi\psi\rangle$ in 3D. We first introduce an embedding
formalism for 3D spinors and compute the conformal blocks appearing in fermion
4-point functions. Using these results, we find general bounds on the
dimensions of operators appearing in the $\psi \times \psi$ OPE, and also on
the central charge $C_T$. We observe features in our bounds that coincide with
scaling dimensions in the Gross-Neveu models at large $N$. We also speculate
that other features could coincide with a fermionic CFT containing no relevant
scalar operators.Comment: 45 pages, 8 figures; V2: added references and small clarifications to
  match JHEP versio
Hydrodynamical noise and Gubser flow

Hydrodynamical noise is introduced on top of Gubser's analytical solution to
viscous hydrodynamics. With respect to the ultra-central collision events of
Pb-Pb, p-Pb and p-p at the LHC energies, we solve the evolution of noisy fluid
systems and calculate the radial flow velocity correlations. We show that the
absolute amplitude of the hydrodynamical noise is determined by the
multiplicity of the collision event. The evolution of azimuthal anisotropies,
which is related to the generation of harmonic flow, receives finite
enhancements from hydrodynamical noise. Although it is strongest in the p-p
systems, the effect of hydrodynamical noise on flow harmonics is found to be
negligible, especially in the ultra-central Pb-Pb collisions. For the
short-range correlations, hydrodynamical noise contributes to the formation of
a near-side peak on top of the correlation structure originated from initial
state fluctuations. The shape of the peak is affected by the strength of
hydrodynamical noise, whose height and width grow from the Pb-Pb system to the
p-Pb and p-p systems.Comment: 22 pages and 4 figures. Text and figures updated. New references
  added. Version to appear in JHE
High energy resummation of transverse momentum distributions:Higgs in
  gluon fusion

We derive a general resummation formula for transverse-momentum distributions
of hard processes at the leading logarithmic level in the high-energy limit, to
all orders in the strong coupling. Our result is based on a suitable
generalization of high-energy factorization theorems, whereby all-order
resummation is reduced to the determination of the Born-level process but with
incoming off-shell gluons. We validate our formula by applying it to Higgs
production in gluon fusion in the infinite top mass limit. We check our result
up to next-to-leading order by comparison to the high energy limit of the exact
expression and to next-to-next-to leading by comparison to NNLL order trasverse
momentum (Sudakov) resummation, and we predict the high-energy behaviour at
next$^3$-to-leading order. We also show that the structure of the result in the
small transverse momentum limit agrees to all orders with general constraints
from Sudakov resummation.Comment: 28 pages, 6 figures, Final version published in JHEP: several typos
  corrected (including in equations
Heavy-flavour production in high-energy d-Au and p-Pb collisions

Soft-hadron measurements in high-energy collisions of small systems like p-Pb
and d-Au show peculiar qualitative features (long-range rapidity correlations,
flattening of the $p_T$-spectra with increasing hadron mass and centrality,
non-vanishing Fourier harmonics in the azimuthal particle distributions)
suggestive of the formation of a strongly-interacting medium displaying a
collective behaviour, with a hydrodynamic flow as a response to the pressure
gradients in the initial conditions. Hard observables (high-$p_T$ jet and
hadron spectra) on the other hand, within the current large systematic
uncertainties, appear only midly modified with the respect to the benchmark
case of minimum-bias p-p collisions. What should one expect for heavy-flavour
particles, initially produced in hard processes but tending, in the
nucleus-nucleus case, to approach kinetic equilibrium with the rest of the
medium? This is the issue we address in the present study, showing how the
current experimental findings are compatible with a picture in which the
formation of a hot medium even in proton-nucleus collisions modifies the
propagation and hadronization of heavy-flavour particles.Comment: Final version, accepted for publication by JHE
Fitting fermion masses and mixings in F-theory GUTs

We analyse the structure of Yukawa couplings in local SU(5) F-theory models
with $E_7$ enhancement. These models are the minimal setting in which the whole
flavour structure for the MSSM charged fermions is encoded in a small region of
the entire compactification space. In this setup the $E_7$ symmetry is broken
down to SU(5) by means of a 7-brane T-brane background, and further to the MSSM
gauge group by means of a hypercharge flux that also implements doublet-triplet
splitting. At tree-level only one family of quarks and charged leptons is
massive, while the other two obtain hierarchically smaller masses when stringy
non-perturbative effects are taken into account. We find that there is a unique
$E_7$ model with such hierarchical flavour structure. The relative simplicity
of the model allows to perform the computation of Yukawa couplings for a region
of its parameter space wider than previous attempts, obtaining realistic
fermion masses and mixings for large parameter regions. Our results are also
valid for local models with $E_8$ enhancement, pointing towards a universal
structure to describe realistic fermion masses within this framework.Comment: 66 pages, 7 figures. v2, corrected typo
Search for charged Higgs bosons in the $H^{\pm} \rightarrow tb$ decay
  channel in $pp$ collisions at $\sqrt{s} = 8$ TeV using the ATLAS detector

Charged Higgs bosons heavier than the top quark and decaying via $H^{\pm}
\rightarrow tb$ are searched for in proton--proton collisions measured with the
ATLAS experiment at $\sqrt{s}=8$ TeV corresponding to an integrated luminosity
of 20.3 fb$^{-1}$. The production of a charged Higgs boson in association with
a top quark, $gb \rightarrow tH^{\pm}$, is explored in the mass range 200 to
600 GeV using multi-jet final states with one electron or muon. In order to
separate the signal from the Standard Model background, analysis techniques
combining several kinematic variables are employed. An excess of events above
the background-only hypothesis is observed across a wide mass range, amounting
to up to 2.4 standard deviations. Upper limits are set on the $gb\rightarrow
tH^{\pm}$ production cross section times the branching fraction
$\mathrm{BR}(H^{\pm} \rightarrow tb)$. Additionally, the complementary
$s$-channel production, $qq' \rightarrow H^{\pm}$, is investigated through a
reinterpretation of $W' \rightarrow tb$ searches in ATLAS. Final states with
one electron or muon are relevant for $H^{\pm}$ masses from 0.4 to 2.0 TeV,
whereas the all-hadronic final state covers the range 1.5 to 3.0 TeV. In these
search channels, no significant excesses from the predictions of the Standard
Model are observed, and upper limits are placed on the $qq' \rightarrow
H^{\pm}$ production cross section times the branching fraction BR$(H^{\pm}
\rightarrow tb)$.Comment: 32 pages plus author list (48 pages total), 10 figures, 4 tables,
  submitted to JHEP. All figures including auxiliary figures are available at
  https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2013-28
Effective Field Theory of Broken Spatial Diffeomorphisms

We study the low energy effective theory describing gravity with broken
spatial diffeomorphism invariance. In the unitary gauge, the Goldstone bosons
associated with broken diffeomorphisms are eaten and the graviton becomes a
massive spin-2 particle with 5 well-behaved degrees of freedom. In this gauge,
the most general theory is built with the lowest dimension operators invariant
under only temporal diffeomorphisms. Imposing the additional shift and SO(3)
internal symmetries, we analyze the perturbations on a FRW background. At
linear perturbation level, the observables of this theory are characterized by
five parameters, including the usual cosmological parameters and one additional
coupling constant for the symmetry-breaking scalars. In the de Sitter and
Minkowski limit, the three Goldstone bosons are supermassive and can be
integrated out, leaving two massive tensor modes as the only propagating
degrees of freedom. We discuss several examples relevant to theories of massive
gravity.Comment: 26 pages, V2 more references, several remarks and a new subsection
  are added, V3 a major revision, with two new subsections added, as well as
  several new discussions on the construction of our EF
Causality Violation, Gravitational Shockwaves and UV Completion

The effective actions describing the low-energy dynamics of QFTs involving
gravity generically exhibit causality violations. These may take the form of
superluminal propagation or Shapiro time advances and allow the construction of
"time machines", i.e. spacetimes admitting closed non-spacelike curves. Here,
we discuss critically whether such causality violations may be used as a
criterion to identify unphysical effective actions or whether, and how,
causality problems may be resolved by embedding the action in a fundamental, UV
complete QFT. We study in detail the case of photon scattering in an
Aichelburg-Sexl gravitational shockwave background and calculate the phase
shifts in QED for all energies, demonstrating their smooth interpolation from
the causality-violating effective action values at low-energy to their
manifestly causal high-energy limits. At low energies, these phase shifts may
be interpreted as backwards-in-time coordinate jumps as the photon encounters
the shock wavefront, and we illustrate how the resulting causality problems
emerge and are resolved in a two-shockwave time machine scenario. The
implications of our results for ultra-high (Planck) energy scattering, in which
graviton exchange is modelled by the shockwave background, are highlighted.Comment: 42 pages, 15 figures, updated reference
SLED Phenomenology: Curvature vs. Volume

We assess the question whether the SLED (Supersymmetric Large Extra
Dimensions) model admits phenomenologically viable solutions with 4D maximal
symmetry. We take into account a finite brane width and a scale invariance (SI)
breaking dilaton-brane coupling, both of which should be included in a
realistic setup. Provided that the microscopic size of the brane is not tuned
much smaller than the fundamental bulk Planck length, we find that either the
4D curvature or the size of the extra dimensions is unacceptably large. Since
this result is independent of the dilaton-brane couplings, it provides the
biggest challenge to the SLED program.
  In addition, to clarify its potential with respect to the cosmological
constant problem, we infer the amount of tuning on model parameters required to
obtain a sufficiently small 4D curvature. A first answer was recently given in
[arXiv:1508.01124], showing that 4D flat solutions are only ensured in the SI
case by imposing a tuning relation, even if a brane-localized flux is included.
In this companion paper, we find that the tuning can in fact be avoided for
certain SI breaking brane-dilaton couplings, but only at the price of worsening
the phenomenological problem.
  Our results are obtained by solving the full coupled Einstein-dilaton system
in a completely consistent way. The brane width is implemented using a
well-known ring regularization. In passing, we note that for the couplings
considered here the results of [arXiv:1508.01124] (which only treated
infinitely thin branes) are all consistently recovered in the thin brane limit,
and how this can be reconciled with the concerns about their correctness,
recently brought up in [arXiv:1509.04201].Comment: 28 pages, 4 figure
Disorder Operators in Chern-Simons-Fermion Theories

Building on the recent progress in solving Chern-Simons-matter theories in
the planar limit, we compute the scaling dimensions of a large class of
disorder ("monopole") operators in $U(N)_k$ Chern-Simons-fermion theories at
all 't Hooft couplings $\lambda = N/k$. We find that the lowest-dimension
operator of this sort has dimension $\frac23 k^{3/2}$. We comment on the
implications of these results to analyzing maps of fermionic disorder operators
under 3D bosonization.Comment: 22 pages, one figure, v2: added a few comments and reference
The slow expansion with nonminimal derivative coupling and its conformal
  dual

We show that the primordial gravitational wave with scale-invariant spectrum
might emerge from a nearly Minkowski space, in which the gravity is
asymptotic-past free. We illustrate it with a model, in which the derivative of
background scalar field nonminimally couples to gravity. We also show that
since here the tensor perturbation is dominated by its growing mode,
mathematically our slowly expanding background is conformally dual to the
matter contraction, but there is no the anisotropy problem.Comment: 24 pages, 4 figures; published version in JHEP; details supplemented,
  references and comments added, presentation improve
Obstruction of black hole singularity by quantum field theory effects

We consider the back reaction of the energy due to quantum fluctuation of the
background fields considering the trace anomaly for Schwarzschild black hole.
It is shown that it will result in modification of the horizon and also
formation of an inner horizon. We show that the process of collapse of a thin
shell stops before formation of the singularity at a radius slightly smaller
than the inner horizon at the order of $(c_{A}\frac{M}{M_p})^{1/3}l_p$. After
the collapse stops the reverse process takes place. Thus we demonstrate that
without turning on quantum gravity and just through the effects the coupling of
field to gravity as trace anomaly of quantum fluctuations the formation of the
singularity through collapse is obstructed. An important consequence of our
work is existence of an extremal solution with zero temperature and a mass
which is lower bound for the Schwazschild solution. This solution is also the
asymptotic final stable state after Hawking radiation.Comment: 19 pages. Discussions improved. References added. Version published
  in Journal of High Energy Physics, 2016(3), 1-2
Towards an Effective Field Theory on the Light-Shell

We discuss our work toward the construction of a light-shell effective theory
(LSET), an effective field theory for describing the matter emerging from
high-energy collisions and the accompanying radiation. We work in the highly
simplified venue of 0-flavor scalar quantum electrodynamics, with a gauge
invariant product of scalar fields at the origin of space-time as the source of
high-energy charged particles. Working in this simple gauge theory allows us to
focus on the essential features of LSET. We describe how the effective theory
is constructed and argue that it can reproduce the full theory tree-level
amplitude. We study the 1-loop radiative corrections in the LSET and suggest
how the leading double-logs in the full theory at 1-loop order can be
reproduced by a purely angular integral in the LSET.Comment: 14 page
Electric-magnetic deformations of D=4 gauged supergravities

We discuss duality orbits and symplectic deformations of D=4 gauged
supergravity theories, with focus on N$\ge$2. We provide a general constructive
framework for computing symplectic deformations starting from a reference
gauging, and apply it to many interesting examples. We prove that no continuous
deformations are allowed for Fayet-Iliopoulos gaugings of the N=2 STU model and
in particular that any $\omega$ deformation is classically trivial. We further
show that although in the N=6 truncation of SO(8) maximal supergravity the
$\omega$ parameter can be dualized away, in the 'twin' N=2 truncation $\omega$
is preserved and a second, new deformation appears. We further provide a full
classification and appropriate duality orbits of certain N=4 gauged
supergravities, including all inequivalent SO(4)$^2$ gaugings and several
non-compact forms.Comment: 33 page
$\tau$ dipole moments via radiative leptonic $\tau$ decays

We propose a new method to probe the magnetic and electric dipole moments of
the $\tau$ lepton using precise measurements of the differential rates of
radiative leptonic $\tau$ decays at high-luminosity $B$ factories. Possible
deviations of these moments from the Standard Model values are analyzed in an
effective Lagrangian approach, thus providing model-independent results.
Analytic expressions for the relevant non-standard contributions to the
differential decay rates are presented. Earlier proposals to probe the $\tau$
dipole moments are examined. A detailed feasibility study of our method is
performed in the conditions of the Belle and Belle II experiments at the KEKB
and Super-KEKB colliders, respectively. This study shows that our approach,
applied to the planned full set of Belle II data for radiative leptonic $\tau$
decays, has the potential to improve the present experimental bound on the
$\tau$ anomalous magnetic moment. On the contrary, its foreseen sensitivity is
not expected to lower the current experimental limit on the $\tau$ electric
dipole moment.Comment: 20 pages, 2 figure
Two-loop conformal generators for leading-twist operators in QCD

QCD evolution equations in minimal subtraction schemes have a hidden
symmetry: One can construct three operators that commute with the evolution
kernel and form an $SL(2)$ algebra, i.e. they satisfy (exactly) the $SL(2)$
commutation relations. In this paper we find explicit expressions for these
operators to two-loop accuracy going over to QCD in non-integer $d=4-2\epsilon$
space-time dimensions at the intermediate stage. In this way conformal symmetry
of QCD is restored on quantum level at the specially chosen (critical) value of
the coupling, and at the same time the theory is regularized allowing one to
use the standard renormalization procedure for the relevant Feynman diagrams.
Quantum corrections to conformal generators in $d=4-2\epsilon$ effectively
correspond to the conformal symmetry breaking in the physical theory in four
dimensions and the $SL(2)$ commutation relations lead to nontrivial constraints
on the renormalization group equations for composite operators. This approach
is valid to all orders in perturbation theory and the result includes
automatically all terms that can be identified as due to a nonvanishing QCD
$\beta$-function (in the physical theory in four dimensions). Our result can be
used to derive three-loop evolution equations for flavor-nonsinglet
quark-antiquark operators including mixing with the operators containing total
derivatives. These equations govern, e.g., the scale dependence of generalized
hadron parton distributions and light-cone meson distribution amplitudes.Comment: 36 page