pinecone/core-2020-05-10-deduplication huggingface dataset:
Implications of unitarity and gauge invariance for simplified dark
  matter models

We show that simplified models used to describe the interactions of dark
matter with Standard Model particles do not in general respect gauge invariance
and that perturbative unitarity may be violated in large regions of the
parameter space. The modifications necessary to cure these inconsistencies may
imply a much richer phenomenology and lead to stringent constraints on the
model. We illustrate these observations by considering the simplified model of
a fermionic dark matter particle and a vector mediator. Imposing gauge
invariance then leads to strong constraints from dilepton resonance searches
and electroweak precision tests. Furthermore, the new states required to
restore perturbative unitarity can mix with Standard Model states and mediate
interactions between the dark and the visible sector, leading to new
experimental signatures such as invisible Higgs decays. The resulting
constraints are typically stronger than the 'classic' constraints on DM
simplified models such as monojet searches and make it difficult to avoid
thermal overproduction of dark matter.Comment: 25 pages + appendices, 10 figures; v2: monojet bounds added, relic
  density calculation corrected, discussion of small couplings included,
  matches published versio
Master integrals for splitting functions from differential equations in
  QCD

A method for calculating phase-space master integrals for the decay process
$1 \to n$ massless partons in QCD using integration-by-parts and differential
equations techniques is discussed. The method is based on the appropriate
choice of the basis for master integrals which leads to significant
simplification of differential equations. We describe an algorithm how to
construct the desirable basis, so that the resulting system of differential
equations can be recursively solved in terms of (G)HPLs as a series in the
dimensional regulator $\epsilon$ to any order. We demonstrate its power by
calculating master integrals for the NLO time-like splitting functions and
discuss future applications of the proposed method at the NNLO precision.Comment: 18 pages, 3 figures; v2: revised Introduction and Bibliograph
ALPtraum: ALP production in proton beam dump experiments

With their high beam energy and intensity, existing and near-future proton
beam dumps provide an excellent opportunity to search for new very weakly
coupled particles in the MeV to GeV mass range. One particularly interesting
example is a so-called axion-like particle (ALP), i.e. a pseudoscalar coupled
to two photons. The challenge in proton beam dumps is to reliably calculate the
production of the new particles from the interactions of two composite objects,
the proton and the target atoms. In this work we argue that Primakoff
production of ALPs proceeds in a momentum range where production rates and
angular distributions can be determined to sufficient precision using simple
electromagnetic form factors. Reanalysing past proton beam dump experiments for
this production channel, we derive novel constraints on the parameter space for
ALPs. We show that the NA62 experiment at CERN could probe unexplored parameter
space by running in 'dump mode' for a few days and discuss opportunities for
future experiments such as SHiP.Comment: 21 pages + appendices, 9 figures, v2: matches version published in
  JHE
Stress-tensor OPE in N=2 Superconformal Theories

We carry out a detailed superspace analysis of the OPE of two N=2
stress-tensor multiplets. Knowledge of the multiplets appearing in the
expansion, together with the two-dimensional chiral algebra description of N=2
SCFTs, imply an analytic bound on the central charge c. This bound is valid for
any N=2 SCFT regardless of its matter content and flavor symmetries, and is
saturated by the simplest Argyres-Douglas fixed point. We also present a
partial conformal block analysis for the scalar superconformal primary of the
multiplet.Comment: 29 page
Causality Constraints on Corrections to the Graviton Three-Point
  Coupling

We consider higher derivative corrections to the graviton three-point
coupling within a weakly coupled theory of gravity. Lorentz invariance allows
further structures beyond the one present in the Einstein theory. We argue that
these are constrained by causality. We devise a thought experiment involving a
high energy scattering process which leads to causality violation if the
graviton three-point vertex contains the additional structures. This violation
cannot be fixed by adding conventional particles with spins $J \leq 2$. But, it
can be fixed by adding an infinite tower of extra massive particles with higher
spins, $J > 2$. In AdS theories this implies a constraint on the conformal
anomaly coefficients $\left|{a - c \over c} \right| \lesssim {1 \over
\Delta_{gap}^2}$ in terms of $\Delta_{gap}$, the dimension of the lightest
single particle operator with spin $J > 2$. For inflation, or de Sitter-like
solutions, it indicates the existence of massive higher spin particles if the
gravity wave non-gaussianity deviates significantly from the one computed in
the Einstein theory.Comment: 50+22 pages, 13 figure
Towards a Theory of the QCD String

We construct a new model of four-dimensional relativistic strings with
integrable dynamics on the worldsheet. In addition to translational modes this
model contains a single massless pseudoscalar worldsheet field - the worldsheet
axion. The axion couples to a topological density which counts the
self-intersection number of a string. The corresponding coupling is fixed by
integrability to $Q=\sqrt{7\over 16\pi}\approx 0.37$. We argue that this model
is a member of a larger family of relativistic non-critical integrable string
models. This family includes and extends conventional non-critical strings
described by the linear dilaton CFT. Intriguingly, recent lattice data in
$SU(3)$ and $SU(5)$ gluodynamics reveals the presence of a massive pseudoscalar
axion on the worldsheet of confining flux tubes. The value of the corresponding
coupling, as determined from the lattice data, is equal to
$Q_L\approx0.38\pm0.04$.Comment: 33 pages, 7 figure
Implications of the CMS search for W_R on Grand Unification

The CMS experiment at the Large Hadron Collider has reported a 2.8$\sigma$
excess in the $(2e)(2jets)$ channel around 2.1 TeV. Interpretation of this data
is reconsidered in terms of the production of a right-handed weak gauge boson,
$W_R$, of the left-right symmetric model and in an $SO(10)$ grand unified
theory abiding by the Extended Survival Hypothesis. The left-right symmetric
model can be consistent with this excess if (a) the heavy right-handed neutrino
has a mass near $W_R$, or (b) if $g_L \neq g_R$, or (c) the right-handed CKM
matrix is nontrivial. Combinations of the above possibilities are also viable.
A $W_R$ with a mass in the TeV region if embedded in $SO(10)$ is not compatible
with $g_L = g_R$. Rather, it implies $0.64 \leq g_R/g_L \leq 0.78$. Further, a
unique symmetry-breaking route -- the order being left-right discrete symmetry
breaking first, followed by $SU(4)_C$ and finally $SU(2)_R$ -- to the standard
model is picked out. The $L \leftrightarrow R$ discrete symmetry has to be
broken at around $10^{16}$ GeV. The grand unification scale is pushed to
$10^{18}$ GeV making the detection of proton decay in ongoing searches rather
unlikely. The $SU(4)_C$ breaking scale can be at its allowed lower limit of
$10^6$ GeV so that $n - \bar{n}$ oscillation or flavour changing processes such
as $K_L \rightarrow \mu e$ and $B_{d,s} \rightarrow \mu e$ may be detectable.
The Higgs scalar multiplets responsible for $SO(10)$ symmetry breaking at
various stages are uniquely identified so long as one adheres to a minimalist
principle. We also remark, {\em en passant}, about a partially unified
Pati-Salam model.Comment: 21 pages, v2: Published version. Clarifications and references adde
Wrapping corrections for non-diagonal boundaries in AdS/CFT

We consider an open string stretched between a Y=0 brane and a Y_theta=0
brane. The latter brane is rotated with respect to the former by an angle
theta, and is described by a non-diagonal boundary S-matrix. This system
interpolates smoothly between the Y-Y (theta =0) and the Y-bar Y (theta = pi/2)
systems, which are described by diagonal boundary S-matrices. We use
integrability to compute the energies of one-particle states at weak coupling
up to leading wrapping order (4, 6 loops) as a function of the angle. The
results for the diagonal cases exactly match with those obtained previously.Comment: 21 pages, 1 figur
Fine-tuning with Brane-Localized Flux in 6D Supergravity

There are claims in the literature that the cosmological constant problem
could be solved in a braneworld model with two large (micron-sized)
supersymmetric extra dimensions. The mechanism relies on two basic ingredients:
First, the cosmological constant only curves the compact bulk geometry into a
rugby shape while the 4D curvature stays flat. Second, a brane-localized flux
term is introduced in order to circumvent Weinberg's fine-tuning argument,
which otherwise enters here through a backdoor via the flux quantization
condition. In this paper, we show that the latter mechanism does not work in
the way it was designed: The only localized flux coupling that guarantees a
flat on-brane geometry is one which preserves the scale invariance of the bulk
theory. Consequently, Weinberg's argument applies, making a fine-tuning
necessary again. The only remaining window of opportunity lies within scale
invariance breaking brane couplings, for which the tuning could be avoided.
Whether the corresponding 4D curvature could be kept under control and in
agreement with the observed value will be answered in our companion paper
[arXiv:1512.03800].Comment: 16 page
Probing crunching AdS cosmologies

Holographic gravity duals of deformations of CFTs formulated on de Sitter
spacetime contain FRW geometries behind a horizon, with cosmological big crunch
singularities. Using a specific analytically tractable solution within a
particular single scalar truncation of N=8 supergravity on AdS_4, we first
probe such crunching cosmologies with spacelike radial geodesics that compute
spatially antipodal correlators of large dimension boundary operators. At late
times, the geodesics lie on the FRW slice of maximal expansion behind the
horizon. The late time two-point functions factorise, and when transformed to
the Einstein static universe, they exhibit a temporal non-analyticity
determined by the maximal value of the scale factor a_{max} . Radial geodesics
connecting antipodal points necessarily have de Sitter energy E \leq a_{max},
while geodesics with E > a_{max} terminate at the crunch, the two categories of
geodesics being separated by the maximal expansion slice. The spacelike crunch
singularity is curved "outward" in the Penrose diagram for the deformed AdS
backgrounds, and thus geodesic limits of the antipodal correlators do not
directly probe the crunch. Beyond the geodesic limit, we point out that the
scalar wave equation, analytically continued into the FRW patch, has a
potential which is singular at the crunch along with complex WKB turning points
in the vicinity of the FRW crunch. We then argue that the frequency space
Green's function has a branch point determined by a_{max} which corresponds to
the lowest quasinormal frequency.Comment: 57 pages, 10 figures. Minor corrections, version to appear in JHE
Light dark matter candidates in intense laser pulses II: the relevance
  of the spin degrees of freedom

Optical searches assisted by the field of a laser pulse might allow for
exploring a variety of not yet detected dark matter candidates such as
hidden-photons and scalar minicharged particles. These hypothetical degrees of
freedom may be understood as a natural consequence of extensions of the
Standard Model incorporating a hidden $\rm U(1)$-gauge sector. In this paper,
we study the effects induced by both candidates on the propagation of a probe
electromagnetic waves in the vacuum polarized by a long laser pulse of moderate
intensity, this way complementing our previous study [JHEP \textbf{06}, $177$
($2015$)]. We describe how the absence of a spin in the scalar charged carriers
modifies the photon-paraphoton oscillations as compared with a fermionic
minicharge model. In particular, we find that the regime close to their lowest
threshold mass might provide the most stringent upper limit for minicharged
scalars. The pure-laser based experiment investigated here could allow 23for
excluding a sector in the parameter space of the particles which has not been
experimentally ruled out by setups driven by dipole magnets. We explain how the
sign of the ellipticity and rotation of the polarization plane acquired by a
probe photon--in combination with their dependencies on the pulse
parameters--can be exploited to elucidate the quantum statistics of the charge
carriers.Comment: 24 pages, 7 figure
Boson Stars from Self-Interacting Dark Matter

We study the possibility that self-interacting bosonic dark matter forms
star-like objects. We study both the case of attractive and repulsive
self-interactions, and we focus particularly in the parameter phase space where
self-interactions can solve well standing problems of the collisionless dark
matter paradigm. We find the mass radius relations for these dark matter
bosonic stars, their density profile as well as the maximum mass they can
support.Comment: 12 pages, 6 figures; references adde
Numerical Evaluation of Two-Loop Integrals in FDR

We present a method to numerically evaluate infrared-finite one- and two-loop
integrals within the Four-Dimensional Regularization/Renormalization approach,
in which a small mass serves as regulator. Typical integrals exhibit a
logarithmic dependence on this mass, which we extract with the aid of suitable
subtraction terms that can easily be integrated analytically until the
logarithmic structure is revealed. As first physical applications to test the
method, we calculate QCD corrections to the decay rates of scalar and
pseudoscalar Higgs bosons into two photons in the limit of an infinite
top-quark mass as well as to the $\rho$ parameter.Comment: 18 pages, 2 figures, v2: minor corrections, citations adde
Noether's Second Theorem and Ward Identities for Gauge Symmetries

Recently, a number of new Ward identities for large gauge transformations and
large diffeomorphisms have been discovered. Some of the identities are
reinterpretations of previously known statements, while some appear to be
genuinely new. We use Noether's second theorem with the path integral as a
powerful way of generating these kinds of Ward identities. We reintroduce
Noether's second theorem and discuss how to work with the physical remnant of
gauge symmetry in gauge fixed systems. We illustrate our mechanism in Maxwell
theory, Yang-Mills theory, p-form field theory, and Einstein-Hilbert gravity.
We comment on multiple connections between Noether's second theorem and known
results in the recent literature. Our approach suggests a novel point of view
with important physical consequences.Comment: 24 pages, 3 figures. v2: references added, minor typos correcte
$\chi_{cJ}\rightarrow e^{+}e^{-}$ decays revisited

We present a calculation of the width for $\chi_{cJ}\rightarrow e^{+}e^{-}$
decay. The amplitude of the process is computed within the NRQCD framework. The
leading-order contribution is described by two terms associated with the two
different integration domains in the electromagnetic loop describing two-photon
annihilation of the heavy quark-antiquark pair. The corresponding operators are
defined in the framework of NRQCD. The matrix element of one of these operators
describes a configuration with an ultrasoft photon and can be associated with
the higher Fock state of the heavy meson. In order to compute this contribution
we use the heavy hadron chiral perturbation theory. We obtain that this
contribution is numerically dominant. The obtained estimates for the decay
widths of the $\chi_{c1}$ and $\chi_{c2}$ states are $0.09$ eV and $0.06$ eV,
respectively.Comment: revised version, couple mistakes in analytical expressions are fixed,
  numerical results for chi_{c2} are slightly modifie
Entanglement Entropy in Warped Conformal Field Theories

We present a detailed discussion of entanglement entropy in (1+1)-dimensional
Warped Conformal Field Theories (WCFTs). We implement the Rindler method to
evaluate entanglement and Renyi entropies for a single interval and along the
way we interpret our results in terms of twist field correlation functions.
Holographically a WCFT can be described in terms of Lower Spin Gravity, a
SL(2,R)xU(1) Chern-Simons theory in three dimensions. We show how to obtain the
universal field theory results for entanglement in a WCFT via holography. For
the geometrical description of the theory we introduce the concept of geodesic
and massive point particles in the warped geometry associated to Lower Spin
Gravity. In the Chern-Simons description we evaluate the appropriate Wilson
line that captures the dynamics of a massive particle.Comment: 37 pages + appendix, 2 figures; v2: minor changes, references added;
  v3: references added; v4: error corrected in derivation of twist operator
  dimensions, results unchange
Thermalon mediated phase transitions in Gauss-Bonnet gravity

Thermalons can mediate phase transitions between different vacua in higher
curvature gravity, potentially changing the asymptotic structure of the
spacetime. Treating the cosmological constant as a dynamical parameter, we
study these phase transitions in the context of extended thermodynamic phase
space. We find that in addition to the AdS to dS phase transitions previously
studied, thermal AdS space can undergo a phase transition to an asymptotically
flat black hole geometry. In the context of AdS to AdS transitions, we comment
on the similarities and differences between thermalon transitions and the
Hawking-Page transition.Comment: 20 pages, 11 figures; reference added, corrected to match published
  versio
Exotic see-saw mechanism for neutrinos and leptogenesis in a Pati-Salam
  model

We discuss non-perturbative corrections to the neutrino sector, in the
context of a D-brane Pati-Salam-like model, that can be obtained as a simple
alternative to $SO(10)$ GUT's in theories with open and unoriented strings. In
such D-brane models, exotic stringy instantons can correct the right-handed
neutrino mass matrix in a calculable way, thus affecting mass hierarchies and
modifying the see-saw mechanism to what we name exotic see-saw. For a wide
range of parameters, a compact spectrum of right-handed neutrino masses can
occur that gives rise to a predictive scenario for low energy observables. This
model also provides a viable mechanism for Baryon Asymmetry in the Universe
(BAU) through leptogenesis. Finally, a Majorana mass for the neutron is
naturally predicted in the model, leading to potentially testable
neutron-antineutron oscillations. Combined measurements in neutrino and
neutron-antineutron sectors could provide precious informations on physics at
the quantum gravity scale.Comment: 35 pages, 2 figures, matches the journal versio
Holographic entanglement entropy from minimal surfaces with/without
  extrinsic curvature

In this paper we show that in addition to the known minimal surfaces which
appear in the literature for computing the entanglement entropy there are other
minimal surfaces with non-zero extrinsic curvature. We use the approach of
regularization procedure for computing the quadratic and cubic curvature
invariants on manifolds with squashed cones. The results can be used to find
the leading and universal terms of the holographic entanglement entropy to
understand which solution corresponds to the actual minimal surface.Comment: 19 pages, 5 figures. v3: Published version in JHE
A Radiative Model for the Weak Scale and Neutrino Mass via Dark Matter

We present a three-loop model of neutrino mass in which both the weak scale
and neutrino mass arise as radiative effects. In this approach, the scales for
electroweak symmetry breaking, dark matter, and the exotics responsible for
neutrino mass, are related due to an underlying scale-invariance. This
motivates the otherwise-independent O(TeV) exotic masses usually found in
three-loop models of neutrino mass. We demonstrate the existence of viable
parameter space and show that the model can be probed at colliders, precision
experiments, and dark matter direct-detection experiments.Comment: 24 pages, 7 figures; v2 Published versio
Flux Formulation of DFT on Group Manifolds and Generalized
  Scherk-Schwarz Compactifications

A flux formulation of Double Field Theory on group manifold is derived and
applied to study generalized Scherk-Schwarz compactifications, which give rise
to a bosonic subsector of half-maximal, electrically gauged supergravities. In
contrast to the flux formulation of original DFT, the covariant fluxes split
into a fluctuation and a background part. The latter is connected to a
$2D$-dimensional, pseudo Riemannian manifold, which is isomorphic to a Lie
group embedded into O($D,D$). All fields and parameters of generalized
diffeomorphisms are supported on this manifold, whose metric is spanned by the
background vielbein $E_A{}^I \in$ GL($2D$). This vielbein takes the role of the
twist in conventional generalized Scherk-Schwarz compactifications. By doing
so, it solves the long standing problem of constructing an appropriate twist
for each solution of the embedding tensor. Using the geometric structure,
absent in original DFT, $E_A{}^I$ is identified with the left invariant
Maurer-Cartan form on the group manifold, in the same way as it is done in
geometric Scherk-Schwarz reductions. We show in detail how the Maurer-Cartan
form for semisimple and solvable Lie groups is constructed starting from the
Lie algebra. For all compact embeddings in O($3,3$), we calculate $E_A{}^I$.Comment: 40 pages, no figures, minor changes, published versio
Observability of s-channel Heavy Charged Higgs at LHC Using Top Tagging
  Technique

In this paper, the question of observability of a heavy charged Higgs in the
mass range 400 GeV < mH < 1000 GeV, is addressed. The production process is set
to pp -> H+ -> tb at 14 TeV LHC. The analysis benefits from top tagging
technique which is based on finding a fat jet as a result of the boosted top
quark decay in signal events. A detailed hadron level analysis is performed and
selection efficiencies are presented with different charged Higgs mass
hypotheses. Finally running toy experiments and using pseudo-data, a fit over
signal plus background distributions is performed to assess possibility of
reconstructing the charged Higgs peak and its invariant mass measurement. It is
shown that the charged Higgs mass can well be reconstructed in the mass range
500 GeV to 1 TeV, with a signal significance which depends on tanbeta.
Eventually 5sigma discovery and 95% C.L. exclusion contours are also provided.Comment: 20 pages, 19 figures and tables, accepted version to appear in JHE
The long string at the stretched horizon and the entropy of large
  non-extremal black holes

We discuss how long strings can arise at the stretched horizon and how they
can account for the Bekenstein-Hawking entropy. We use the thermal scalar field
theory to derive the asymptotic density of states and corresponding stress
tensor of a microcanonical long string gas in Rindler space. We show that the
equality of the Hagedorn and Hawking temperatures gives rise to the tree-level
entropy of large black holes in accordance with the Bekenstein-Hawking-Wald
formula.Comment: 19 pages, v2: added discussion on rotating black holes, matches
  published versio