pinecone/core-2020-05-10-deduplication huggingface dataset:
Resummation of Transverse Momentum Distributions in Distribution Space

Differential spectra in observables that resolve additional soft or collinear
QCD emissions exhibit Sudakov double logarithms in the form of logarithmic plus
distributions. Important examples are the total transverse momentum $q_T$ in
color-singlet production, N-jettiness (with thrust or beam thrust as special
cases), but also jet mass and more complicated jet substructure observables.
The all-order logarithmic structure of such distributions is often fully
encoded in differential equations, so-called (renormalization group) evolution
equations. We introduce a well-defined technique of distributional scale
setting, which allows one to treat logarithmic plus distributions like ordinary
logarithms when solving these differential equations. In particular, this
allows one (through canonical scale choices) to minimize logarithmic
contributions in the boundary terms of the solution, and to obtain the full
distributional logarithmic structure from the solution's evolution kernel
directly in distribution space. We apply this technique to the $q_T$
distribution, where the two-dimensional nature of convolutions leads to
additional difficulties (compared to one-dimensional cases like thrust), and
for which the resummation in distribution (or momentum) space has been a
long-standing open question. For the first time, we show how to perform the RG
evolution fully in momentum space, thereby directly resumming the logarithms
$[\ln^n(q_T^2/Q^2)/q_T^2]_+$ appearing in the physical $q_T$ distribution. The
resummation accuracy is then solely determined by the perturbative expansion of
the associated anomalous dimensions.Comment: 58 pages + 12 pages in Appendices, 2 figures; v2: minor changes,
  journal versio
Glimpses of black hole formation/evaporation in highly inelastic,
  ultra-planckian string collisions

We revisit possible glimpses of black-hole formation by looking at
ultra-planckian string-string collisions at very high final-state multiplicity.
We compare, in particular, previous results using the optical theorem, the
resummation of ladder diagrams at arbitrary loop order, and the AGK cutting
rules, with the more recent study of $2 \rightarrow N$ scattering at $N \sim s
M_P^{-2} \gg 1$. We argue that some apparent tension between the two approaches
disappears once a reinterpretation of the latter's results in terms of suitably
defined infrared-safe cross sections is adopted. Under that assumption, the
typical final state produced in an ultra-planckian collision does indeed appear
to share some properties with those expected from the evaporation of a black
hole of mass $\sqrt{s}$, although no sign of thermalization is seen to emerge
at this level of approximation.Comment: 39 pages, 6 figure
Multi-Loop Positivity of the Planar ${\cal N}=4$ SYM Six-Point Amplitude

We study the six-point NMHV ratio function in planar ${\cal N}=4$ SYM theory
in the context of positive geometry. The Amplituhedron construction of the
integrand for the amplitudes provides a kinematical region in which the
integrand was observed to be positive. It is natural to conjecture that this
property survives integration, i.e. that the final result for the ratio
function is also positive in this region. Establishing such a result would
imply that preserving positivity is a surprising property of the Minkowski
contour of integration and it might indicate some deeper underlying structure.
We find that the ratio function is positive everywhere we have tested it,
including analytic results for special kinematical regions at one and two
loops, as well as robust numerical evidence through five loops. There is also
evidence for not just positivity, but monotonicity in a "radial" direction. We
also investigate positivity of the MHV six-gluon amplitude. While the remainder
function ceases to be positive at four loops, the BDS-like normalized MHV
amplitude appears to be positive through five loops.Comment: 45 pages, 7 figures, 4 ancillary files. v2: typos corrected; version
  to appear in JHE
A geometrical approach to degenerate scalar-tensor theories

Degenerate scalar-tensor theories are recently proposed covariant theories of
gravity coupled with a scalar field. Despite being characterised by higher
order equations of motion, they do not propagate more than three degrees of
freedom, thanks to the existence of constraints. We discuss a geometrical
approach to degenerate scalar-tensor systems, and analyse its consequences. We
show that some of these theories emerge as a certain limit of DBI Galileons. In
absence of dynamical gravity, these systems correspond to scalar theories
enjoying a symmetry which is different from Galileon invariance. The scalar
theories have however problems concerning the propagation of fluctuations
around a time dependent background. These issues can be tamed by breaking the
symmetry by hand, or by minimally coupling the scalar with dynamical gravity in
a way that leads to degenerate scalar-tensor systems. We show that distinct
theories can be connected by a relation which generalizes Galileon duality, in
certain cases also when gravity is dynamical. We discuss some implications of
our results in concrete examples. Our findings can be helpful for assessing
stability properties and understanding the non-perturbative structure of
systems based on degenerate scalar-tensor systems.Comment: 34 pages, 1 figur
A framework for testing leptonic unitarity by neutrino oscillation
  experiments

If leptonic unitarity is violated by new physics at an energy scale much
lower than the electroweak scale, which we call low-scale unitarity violation,
it has different characteristic features from those expected in unitarity
violation at high-energy scales. They include maintaining flavor universality
and absence of zero-distance flavor transition. We present a framework for
testing such unitarity violation at low energies by neutrino oscillation
experiments. Starting from the unitary 3 active plus $N$ (arbitrary integer)
sterile neutrino model we show that by restricting the active-sterile and
sterile-sterile neutrino mass squared differences to $\gtrsim$ 0.1 eV$^2$ the
oscillation probability in the $(3+N)$ model becomes insensitive to details of
the sterile sector, providing a nearly model-independent framework for testing
low-scale unitarity violation. Yet, the presence of the sterile sector leaves
trace as a constant probability leaking term, which distinguishes low-scale
unitarity violation from the high-scale one. The non-unitary mixing matrix in
the active neutrino subspace is common for the both cases. We analyze how
severely the unitarity violation can be constrained in $\nu_{e}$-row by taking
a JUNO-like setting to simulate medium baseline reactor experiments. Possible
modification of the features of the $(3+N)$ model due to matter effect is
discussed to first order in the matter potential.Comment: Updated to match the published version in JHEP. Added section 5.3 on
  current constraints on unitarity violation. Added analysis for the case of
  reactor neutrino flux uncertainty of 6% in section
Anomalous Triple Gauge Couplings in the Effective Field Theory Approach
  at the LHC

We discuss how to perform consistent extractions of anomalous triple gauge
couplings (aTGC) from electroweak boson pair production at the LHC in the
Standard Model Effective Field Theory (SMEFT). After recasting recent ATLAS and
CMS searches in $pp\to WZ (WW) \to \ell' \nu \ell^+\ell^- (\nu_{\ell})$
channels, we find that: (a) working consistently at order $\Lambda^{-2}$ in the
SMEFT expansion the existing aTGC bounds from Higgs and LEP-2 data are not
improved, (b) the strong limits quoted by the experimental collaboration are
due to the partial $\Lambda^{-4}$ corrections (dimension-6 squared
contributions). Using helicity selection rule arguments we are able to explain
the suppression in some of the interference terms, and discuss conditions on
New Physics (NP) models that can benefit from such LHC analyses. Furthermore,
standard analyses assume implicitly a quite large NP scale, an assumption that
can be relaxed by imposing cuts on the underlying scale of the process
($\sqrt{\hat{s}}$). In practice, we find almost no correlation between
$\sqrt{\hat{s}}$ and the experimentally accessible quantities, which
complicates the SMEFT interpretation. Nevertheless, we provide a method to set
(conservative) aTGC bounds in this situation, and recast the present searches
accordingly. Finally, we introduce a simple NP model for aTGC to compare the
bounds obtained directly in the model with those from the SMEFT analysis.Comment: 31 pages, 13 figures, 4 tables. Version to appear in JHE
Holography, Brane Intersections and Six-dimensional SCFTs

We study supersymmetric intersections of NS5-, D6- and D8-branes in type IIA
string theory. We focus on the supergravity description of this system and
identify a "near horizon" limit in which we recover the recently classified
supersymmetric seven-dimensional AdS solutions of massive type IIA
supergravity. Using a consistent truncation to seven-dimensional gauged
supergravity we construct a universal supersymmetric deformation of these AdS
vacua. In the holographic dual six-dimensional (1,0) superconformal field
theory this deformation describes a universal RG flow on the tensor branch of
the vacuum moduli space triggered by a vacuum expectation value for a protected
scalar operator of dimension four.Comment: 26 pages, 6 figures. v2: Minor corrections, published versio
Superheavy Thermal Dark Matter and Primordial Asymmetries

The early universe could feature multiple reheating events, leading to jumps
in the visible sector entropy density that dilute both particle asymmetries and
the number density of frozen-out states. In fact, late time entropy jumps are
usually required in models of Affleck-Dine baryogenesis, which typically
produces an initial particle-antiparticle asymmetry that is much too large. An
important consequence of late time dilution, is that a smaller dark matter
annihilation cross section is needed to obtain the observed dark matter relic
density. For cosmologies with high scale baryogenesis, followed by
radiation-dominated dark matter freeze-out, we show that the perturbative
unitarity mass bound on thermal relic dark matter is relaxed to $10^{10}$ GeV.
We proceed to study superheavy asymmetric dark matter models, made possible by
a sizable entropy injection after dark matter freeze-out, and identify how the
Affleck-Dine mechanism would generate the baryon and dark asymmetries.Comment: 22 pages, 3 figure
A Systematic Effective Operator Analysis of Semi-Annihilating Dark
  Matter

Semi-annihilation is a generic feature of dark matter theories stabilised by
symmetries larger than a $Z_2$. It contributes to thermal freeze out, but is
irrelevant for direct and collider searches. This allows semi-annihilating dark
matter to avoid those limits in a natural way. We use an effective operator
approach to make the first model-independent study of the associated
phenomenology. We enumerate all possible operators that contribute to $2\to2$
semi-annihilation up to dimension 6, plus leading terms at dimension 7. We find
that when the only light states charged under the dark symmetry are dark
matter, the model space is highly constrained. Only fifteen operators exist,
and just two for single-component dark sectors. If there can be additional
light, unstable "dark partner" states the possible phenomenology greatly
increases, at the cost of additional model dependence in the dark partner decay
modes. We also derive the irreducible constraints on models with
single-component dark matter from cosmic ray searches and astrophysical
observations. We find that for semi-annihilation to electrons and light quarks,
the thermal relic cross sections can be excluded for dark matter masses upComment: 37 pages + appendices and references; 13 figures; 20 tables;
  References update
Strong First Order Electroweak Phase Transition in the CP-Conserving
  2HDM Revisited

The discovery of the Higgs boson by the LHC experiments ATLAS and CMS has
marked a milestone for particle physics. Yet, there are still many open
questions that cannot be answered within the Standard Model (SM). For example,
the generation of the observed matter-antimatter asymmetry in the universe
through baryogenesis can only be explained qualitatively in the SM. A simple
extension of the SM compatible with the current theoretical and experimental
constraints is given by the 2-Higgs-Doublet Model (2HDM) where a second Higgs
doublet is added to the Higgs sector. We investigate the possibility of a
strong first order electroweak phase transition in the CP-conserving 2HDM type
I and type II where either of the CP-even Higgs bosons is identified with the
SM-like Higgs boson. The renormalisation that we apply on the loop-corrected
Higgs potential allows us to efficiently scan the 2HDM parameter space and
simultaneously take into account all relevant theoretical and up-to-date
experimental constraints. The 2HDM parameter regions found to be compatible
with the applied constraints and a strong electroweak phase transition are
analysed systematically. Our results show that there is a strong interplay
between the requirement of a strong phase transition and collider phenomenology
with testable implications for searches at the LHC.Comment: 34 pages, 12 figures, 3 tables. Matches journal version accepted for
  publicatio
A New Approach to Non-Abelian Hydrodynamics

We present a new approach to describe hydrodynamics carrying non-Abelian
macroscopic degrees of freedom. Based on the Kaluza-Klein compactification of a
higher-dimensional neutral dissipative fluid on a group manifold, we obtain a
d=4 colored dissipative fluid coupled to Yang-Mills gauge field. We calculate
the transport coefficients of the new fluid, which show the non-Abelian
character of the gauge group. In particular, we obtain group-valued terms in
the gradient expansions and response quantities such as the conductivity matrix
and the chemical potentials. While using SU(2) for simplicity, this approach is
applicable to any gauge group. Resulting a robust description of non-Abelian
hydrodynamics, we discuss some links between this system and quark-gluon plasma
and fluid/gravity duality.Comment: 41 pages (31 + appendices), 1 figure. V2: Minor modifications, some
  typos fixed and references adde
FIMP and Muon ($g-2$) in a U$(1)_{L_{\mu}-L_{\tau}}$ Model

The tightening of the constraints on the standard thermal WIMP scenario has
forced physicists to propose alternative dark matter (DM) models. One of the
most popular alternate explanations of the origin of DM is the non-thermal
production of DM via freeze-in. In this scenario the DM never attains thermal
equilibrium with the thermal soup because of its feeble coupling strength
($\sim 10^{-12}$) with the other particles in the thermal bath and is generally
called the Feebly Interacting Massive Particle (FIMP). In this work, we present
a gauged U(1)$_{L_{\mu}-L_{\tau}}$ extension of the Standard Model (SM) which
has a scalar FIMP DM candidate and can consistently explain the DM relic
density bound. In addition, the spontaneous breaking of the
U(1)$_{L_{\mu}-L_{\tau}}$ gauge symmetry gives an extra massive neutral gauge
boson $Z_{\mu\tau}$ which can explain the muon ($g-2$) data through its
additional one-loop contribution to the process. Lastly, presence of three
right-handed neutrinos enable the model to successfully explain the small
neutrino masses via the Type-I seesaw mechanism. The presence of the
spontaneously broken U(1)$_{L_{\mu}-L_{\tau}}$ gives a particular structure to
the light neutrino mass matrix which can explain the peculiar mixing pattern of
the light neutrinos.Comment: 30 pages, 8 figures, 3 tables, Version Published in JHE
Quantum vacuum effects on the final fate of a collapsing ball of dust

We consider the quantum vacuum effects of the massless scalar fields that are
non-minimally coupled to the background geometry of a collapsing homogeneous
ball of dust. It is shown that for a definite range of coupling constants,
there are repulsive quantum vacuum effects, capable of stopping the collapse
process inside the black hole and precluding the formation of singularity. The
final fate of the collapse will be a black hole with no singularity, inside
which the matter stays balanced. The density of the final static matter will be
close to the Planck density. We show that the largest possible radius of the
stable static ball inside a black hole with Schwarzschild mass $M$ is given by
${{\left( \frac{1}{90\pi }\frac{M}{{{m}_{p}}} \right)}^{\frac{1}{3}}}{{\ell
}_{p}}$. If the black hole undergoes Hawking radiation, the final state will be
an extremal quantum-corrected black hole, with zero temperature, with a remnant
of matter inside. We show that the resolution of singularity is not disrupted
under Hawking radiation.Comment: 27 pages, discussions improved, one figure and references added,
  version accepted for publication in Journal of High Energy Physics (JHEP
Vector boson production in joint resummation

We study the transverse momentum ($Q_T$) distribution of an electro-weak
vector boson produced via the Drell-Yan mechanism, in the context of joint
resummation. This formalism allows for the simultaneous resummation of
logarithmic contributions that are enhanced at small $Q_T$ and at partonic
threshold. We extend joint resummation to next-to-next-to leading logarithmic
accuracy and we present resummed and matched results for three different
phenomenological setups. In particular, we study the production of a $Z$ boson
at the Tevatron and at the Large Hadron Collider (LHC), as well as the
production of a heavier $Z^\prime$ at the LHC. We compare our findings to
standard $Q_T$ resummation, as well as to fixed-order perturbation theory. We
find that joint resummation provides a moderate (but not flat) correction with
respect to $Q_T$ resummation and it leads to a reduction of the scale
dependence of the results. However, our study also shows some limitations of
this formalism. While the use of joint resummation for $Z$ production at the
Tevatron and $Z^\prime$ production at the LHC appears to be justified, our
implementation suffers from a stronger dependence on power corrections for
processes which are further away from threshold, such as $Z$ production at the
LHC, for which we cannot claim an improvement over standard $Q_T$ resummation.Comment: 28 pages, 10 figures, published versio
Hairy black holes and the endpoint of AdS$_4$ charged superradiance

We construct hairy black hole solutions that merge with the anti-de Sitter
(AdS$_4$) Reissner-Nordstr\"om black hole at the onset of superradiance. These
hairy black holes have, for a given mass and charge, higher entropy than the
corresponding AdS$_4$-Reissner-Nordstr\"om black hole. Therefore, they are
natural candidates for the endpoint of the charged superradiant instability. On
the other hand, hairy black holes never dominate the canonical and
grand-canonical ensembles. The zero-horizon radius of the hairy black holes is
a soliton (i.e. a boson star under a gauge transformation). We construct our
solutions perturbatively, for small mass and charge, so that the properties of
hairy black holes can be used to testify and compare with the endpoint of
initial value simulations. We further discuss the near-horizon scalar
condensation instability which is also present in global
AdS$_4$-Reissner-Nordstr\"om black holes. We highlight the different nature of
the near-horizon and superradiant instabilities and that hairy black holes
ultimately exist because of the non-linear instability of AdS.Comment: 41 pages, 6 figures. v2: Minor changes to match published versio
Naturalness made easy: two-loop naturalness bounds on minimal SM
  extensions

The main result of this paper is a collection of conservative naturalness
bounds on minimal extensions of the standard model by (vector-like) fermionic
or scalar gauge multiplets. Within, we advocate for an intuitive and physical
concept of naturalness built upon the renormalisation group equations. In the
effective field theory of the standard model plus a gauge multiplet with mass
$M$, the low scale Higgs mass parameter is a calculable function of
$\overline{\rm MS}$ input parameters defined at some high scale $\Lambda_h >
M$. If the Higgs mass is very sensitive to these input parameters, then this
signifies a naturalness problem. To sensibly capture the sensitivity, it is
shown how a sensitivity measure can be rigorously derived as a Bayesian model
comparison, which reduces in a relevant limit to a Barbieri--Giudice-like
fine-tuning measure. This measure is fully generalisable to any perturbative
EFT. The interesting results of our two-loop renormalisation group study are as
follows: for $\Lambda_h=\Lambda_{Pl}$ we find "$10\%$ fine-tuning" bounds on
the masses of various gauge multiplets of $M<\mathcal{O}(1$--$10)$ TeV, with
bounds on fermionic gauge multiplets significantly weaker than for scalars;
these bounds remain finite in the limit $\Lambda_h\to M^+$, weakening to
$M<\mathcal{O}(10$--$100)$ TeV; and bounds on coloured multiplets are no more
severe than for electroweak multiplets, since they only directly correct the
Higgs mass at three-loop.Comment: 31 pages, 9 figures; v2: version published in JHE
A simple holographic scenario for gapped quenches

We construct gravitational backgrounds dual to a family of field theories
parameterized by a relevant coupling. They combine a non-trivial scalar field
profile with a naked singularity. The naked singularity is necessary to
preserve Lorentz invariance along the boundary directions. The singularity is
however excised by introducing an infrared cutoff in the geometry. The
holographic dictionary associated to the infrared boundary is developed. We
implement quenches between two different values of the coupling. This requires
considering time dependent boundary conditions for the scalar field both at the
AdS boundary and the infrared wall.Comment: 5 pages, 8 figure
Determining the CP nature of spin-0 mediators in associated production
  of dark matter and $t \bar t$ pairs

In the framework of spin-0 $s$-channel simplified models, we explore the
possibility of assessing the structure of dark matter interactions through the
associate production of dark matter and $t\bar{t}$ pairs. To this purpose,
final states with two leptons are considered and the kinematic properties of
the dilepton system is studied. We develop a realistic analysis strategy and
provide a detailed evaluation of the achievable sensitivity for the dark matter
signal assuming integrated luminosities of $300 \, {\rm fb}^{-1}$ and $3 \,
{\rm ab}^{-1}$ at the 14 TeV LHC. Furthermore, upper limits on the mediator
masses for which the two different CP hypotheses can be distinguished are
derived. The obtained limits on the signal strengths are finally translated
into constraints on the parameter space of two spin-0 simplified models
including a scenario with an extended Higgs sector.Comment: 24 pages, 11 figures; v2: matches published versio