HEP Phenomenology·hep-ph

Mon·Jul 9, 2018Monday·July 9, 2018

23 papers—16 primary·7 cross-listed·reconstructed*

01*
Learning to pinpoint effective operators at the LHC: a study of the $t t ˉ b b ˉ$ signature
Jorgen D'Hondt🇧🇪 · Alberto Mariotti🇧🇪 · Ken Mimasu🇧🇪 · Seth Moortgat🇧🇪 · Cen Zhang🇨🇳
In the context of the Standard Model effective field theory (SMEFT), we study the LHC sensitivity to four fermion operators involving heavy quarks by employing cross section measurements in the $t t ˉ b b ˉ$ final state. Starting from the measurement of total rates, we progressively exploit kinematical information and machine learning techniques to optimize the projected sensitivity at the end of Run III. Indeed, in final states with high multiplicity containing inter-correlated kinematical information, multi-variate methods provide a robust way of isolating the regions of phase space where the SMEFT contribution is enhanced. We also show that training for multiple output classes allows for the discrimination between operators mediating the production of tops in different helicity states. Our projected sensitivities not only constrain a host of new directions in the SMEFT parameter space but also improve on existing limits demonstrating that, on one hand, $t t ˉ b b ˉ$ production is an indispensable component in a future global fit for top quark interactions in the SMEFT, and on the other, multi-class machine learning algorithms can be a valuable tool for interpreting LHC data in this framework.
hep-phJHEP(2018)·40 citations
02*
Prospects for axion searches with Advanced LIGO through binary mergers
Junwu Huang🇨🇦 · Matthew C. Johnson🇨🇦 · Laura Sagunski🇨🇦 · Mairi Sakellariadou🇬🇧 · Jun Zhang🇨🇦
The observation of gravitational waves from a binary neutron star merger by LIGO/VIRGO and the associated electromagnetic counterpart provides a high precision test of orbital dynamics, and therefore a new and sensitive probe of extra forces and new radiative degrees of freedom. Axions are one particularly well-motivated class of extensions to the Standard Model leading to new forces and sources of radiation, which we focus on in this paper. Using an effective field theory (EFT) approach, we calculate the first post-Newtonian corrections to the orbital dynamics, radiated power, and gravitational waveform for binary neutron star mergers in the presence of an axion. This result is applicable to many theories which add an extra massive scalar degree of freedom to General Relativity. We then perform a detailed forecast of the potential for Advanced LIGO to constrain the free parameters of the EFT, and map these to the mass $m_{a}$ and decay constant $f_{a}$ of the axion. At design sensitivity, we find that Advanced LIGO can potentially exclude axions with $m_{a} ≲ 1 0^{- 11} eV$ and $f_{a} \sim (1 0^{14} - 1 0^{17}) GeV$ . There are a variety of complementary observational probes over this region of parameter space, including the orbital decay of binary pulsars, black hole superradiance, and laboratory searches. We comment on the synergies between these various observables.
hep-phastro-ph.COgr-qchep-thPRD(2019)·114 citations
03*
Nature of the $Ω$ (2012) through its strong decays
T. M. Aliev🇹🇷 · K. Azizi🇹🇷 · Y. Sarac🇹🇷 · H. Sundu🇹🇷
We extend our previous analysis on the mass of the recently discovered $Ω (2012)$ state by investigation of its strong decays and calculation of its width employing the method of light cone QCD sum rule. Considering two possibilities for the quantum numbers of $Ω (2012)$ state, namely $1 P$ orbital excitation with $J^{P} = \frac{3}{2}^{-}$ and $2 S$ radial excitation with $J^{P} = \frac{3}{2}^{+}$ , we obtain the strong coupling constants defining the $Ω (1 P /2 S) \to Ξ K$ decays. The results of the coupling constants are then used to calculate the decay width corresponding to each possibility. Comparison of the obtained results on the total widths in this work with the experimental value and taking into account the results of our previous mass prediction on the $Ω (2012)$ state, we conclude that this state is $1 P$ orbital excitation of the ground state $Ω$ baryon, whose quantum numbers are $J^{P} = \frac{3}{2}^{-}$ .
hep-phhep-exhep-latEPJC(2018)·40 citations
04*
A $Z^{'}$ -model and the magnetism of a dark fermion candidate
M. J. Neves🇧🇷 · J. A. Helayël-Neto🇧🇷
Our contribution sets out to investigate the phenomenology of a gauge model based on an $S U_{L} (2) \times U_{R} (1)_{Q} \times U (1)_{Q^{'}}$ -symmetry group. The model can accommodate, through its symmetry-breaking pattern, a candidate to a heavy $Z^{'}$ -boson at the TeV-scale. The extended Higgs sector introduces a heavy scalar whose mass lies in the region $1.2 - 3.7 \mbox T e V$ . The fermion sector includes an exotic candidate to Dark Matter that mixes with the right-handed neutrino component in the Higgs sector, so that the whole field content ensures the cancellation of the $U (1)$ -quiral anomaly. The masses are fixed according to the particular way the symmetry breaking takes place. In view of the possible symmetry breakdown pattern, we study the phenomenological implications in a high-energy scenario. We worek out the magnetic dipole momentum (MDM) of the exotic fermion and the transition MDM due to its mixing with the right-neutrino.
hep-phhep-th0 citations
05*
Neutrino masses, cosmological inflation and dark matter in a $U (1)_{B - L}$ model with type II seesaw mechanism
J. G. Rodrigues🇧🇷 · A. C. O. Santos🇧🇷 · J. G. Ferreira Jr🇧🇷 · C. A. de S. Pires🇧🇷
In this work we implement the type II seesaw mechanism into the framework of the $U (1)_{B - L}$ gauge model. As main gain, the right-handed neutrinos of the model get free to play the role of the dark matter of the universe. As side effect, the model realizes Higgs inflation without problem with loss of unitarity.
hep-phCPC(2021)·6 citations
06*
Scalar resonance in a top partner model
Sebastián Norero🇨🇱 · Juan Yepes🇨🇱 · Alfonso Zerwekh🇨🇱
The phenomenology entailed by a scalar resonance in a top partner model is analysed here in a $S O (5)$ Composite Higgs formalism. Heavy scalar resonances production and their decays modes are explored along a benchmark resonance mass range. The production of single-double partner final states has been scanned along the partner mass scale. QCD drives such production, as well as the SM gauge, Higgs, plus the intermediation of the scalar resonance. Non-zero contributions are induced as long as extra fermion-resonance effects are included. Finally, we have excluded regions of the parameter spaces underlying our framework by imposing the recent LHC searches for vector-like quarks production in $pp$ -collisions at 13 TeV. Substantial reduction of the allowed regions occurs if extra fermion-resonance effects are accounted for, leading us to test the involved parametric dependence in the shed light of new matter interactions.
hep-ph5 citations
07*
Higgs inflation
Javier Rubio🇩🇪
The properties of the recently discovered Higgs boson together with the absence of new physics at collider experiments allows us to speculate about consistently extending the Standard Model of particle physics all the way up to the Planck scale. In this context, the Standard Model Higgs non-minimally coupled to gravity could be responsible for the symmetry properties of the Universe at large scales and for the generation of the primordial spectrum of curvature perturbations seeding structure formation. We overview the minimalistic Higgs inflation scenario, its predictions, open issues and extensions and discuss its interplay with the possible metastability of the Standard Model vacuum.
hep-phastro-ph.COgr-qchep-thFront.Astron.Space Sci.(2019)·255 citations
08*
Scalaron the healer: removing the strong-coupling in the Higgs- and Higgs-dilaton inflations
Dmitry Gorbunov🇷🇺 · Anna Tokareva🇷🇺
We show that introducing $R^{2}$ -term makes the Higgs-inflation and Higgs-dilaton inflation consistent models: the strong coupling energy scales in scalar, gauge and gravity sectors all are lifted up to the Planck scale.
hep-phhep-thPLB(2019)·123 citations
09*
Gravitationally produced Top Quarks and the Stability of the Electroweak Vacuum During Inflation
David Rodriguez-Roman🇬🇧 · Malcolm Fairbairn🇬🇧
In the standard model the (Brout-Englert-)Higgs quartic coupling becomes negative at high energies rendering our current electroweak vacuum metastable, but with an instability timescale much longer than the age of the Current Universe. During cosmological Inflation, unless there is a non-minimal coupling to gravity, the Higgs field is pushed away from the origin of its potential due to quantum fluctuations. It is therefore a mystery how we have remained in our current vacuum if we went through such a period of Inflation. In this work we study the effect of top quarks created gravitationally during Inflation and their effect upon the Higgs potential using only General Relativity with minimal couplings and Standard Model particle physics. We show how the evolution of the Higgs field during Inflation is modified coming to the conclusion that this effect is non negligible for scales of Inflation close to or larger than the stability scale but small for scales where the Higgs is stable. Also, we briefly discuss the effect of other fermions to the Higgs instability.
hep-phgr-qchep-thPRD(2019)·13 citations
10*
Phenomenological Constraints on Anomaly-Free Dark Matter Models
John Ellis🇬🇧 · Malcolm Fairbairn🇬🇧 · Patrick Tunney🇬🇧
We study minimal benchmark models of dark matter with an extra anomaly-free U(1)' gauge boson Z'. We find model parameters that give rise to the correct cosmological dark matter density while evading the latest direct detection searches for dark matter scattering produced by the XENON1T experiment, including the effects of Z-Z' mixing. We also find regions of parameter space that evade the constraints from LHC measurements of dileptons and dijets, precision electroweak measurements, and LHC searches for monojet events with missing transverse energy. We study two benchmark Z' models with Y-sequential couplings to quarks and leptons, one with a vector-like coupling to the dark matter particle and one with an axial dark matter coupling. The vector-like model is extremely tightly constrained, with only a narrow allowed strip where $m_{χ} ≃ M_{Z^{'}} /2$ , and the axial model is excluded within the parameter range studied. We also consider two leptophobic Z $^{'}$ benchmark models, finding again narrow allowed strips where $m_{χ} ≃ M_{Z^{'}} /2$ as well as more extended regions where $lo g_{10} (m_{χ} / GeV) ≳ 3.2$ .
hep-phhep-ex24 citations
11*
Transversal Modes and Higgs Bosons in Electroweak Vector-Boson Scattering at the LHC
Simon Braß🇩🇪 · Christian Fleper🇩🇪 · Wolfgang Kilian🇩🇪 · Jürgen Reuter🇩🇪 · Marco Sekulla🇩🇪
Processes where $W$ and $Z$ bosons scatter into pairs of electroweak bosons $W$ , $Z$ , and Higgs, are sensitive probes of new physics in the electroweak sector. We study simplified models that describe typical scenarios of new physics and parameterize the range of possible LHC results between the Standard-Model prediction and unitarity limits. Extending the study beyond purely longitudinal scattering, we investigate the role of transversally polarized gauge bosons. Unitarity becomes an essential factor, and limits on parameters matched to the naive perturbative low-energy effective theory turn out to be necessarily model-dependent. We discuss the implications of our approach for the interpretation of LHC data on vector-boson scattering and Higgs-pair production.
hep-phhep-exEPJC(2018)·44 citations
12*
Master formula for $ε^{'} / ε$ beyond the Standard Model
Jason Aebischer🇩🇪 · Christoph Bobeth🇩🇪 · Andrzej J. Buras🇩🇪 · Jean-Marc Gérard🇧🇪 · David M. Straub🇩🇪
We present for the first time a master formula for $ε^{'} / ε$ , the ratio probing direct CP violation in $K \to π π$ decays, valid in any theory beyond the Standard Model (BSM). The formula makes use of hadronic matrix elements of BSM operators calculated recently in the Dual QCD approach and the ones of the SM operators from lattice QCD. We emphasize the large impact of several scalar and tensor BSM operators in the context of the emerging $ε^{'} / ε$ anomaly. We have implemented the results in the open source code flavio.
hep-phhep-exhep-latPLB(2019)·51 citations
13*
Cuckoo's Eggs in Neutron Stars: Can LIGO Hear Chirps from the Dark Sector?
Joachim Kopp (JGU Mainz & CERN)🇩🇪 · Ranjan Laha (JGU Mainz)🇩🇪 · Toby Opferkuch (JGU Mainz)🇩🇪 · William Shepherd (JGU Mainz)🇩🇪
We explore in detail the possibility that gravitational wave signals from binary inspirals are affected by a new force that couples only to dark matter particles. We discuss the impact of both the new force acting between the binary partners as well as radiation of the force carrier. We identify numerous constraints on any such scenario, ultimately concluding that observable effects on the dynamics of binary inspirals due to such a force are not possible if the dark matter is accrued during ordinary stellar evolution. Constraints arise from the requirement that the astronomical body be able to collect and bind at small enough radius an adequate number of dark matter particles, from the requirement that the particles thus collected remain bound to neutron stars in the presence of another neutron star, and from the requirement that the theory allows old neutron stars to exist and retain their charge. Thus, we show that any deviation from the predictions of general relativity observed in binary inspirals must be due either to the material properties of the inspiraling objects themselves, such as a tidal deformability, to a true fifth force coupled to baryons, or to a non-standard production mechanism for the dark matter cores of neutron stars. Viable scenarios of the latter type include production of dark matter in exotic neutron decays, or the formation of compact dark matter objects in the early Universe that later seed star formation or are captured by stars.
hep-phastro-ph.COgr-qchep-exJHEP(2018)·61 citations
14*
NNLO QCD Corrections to Jet Production in Charged Current Deep Inelastic Scattering
J. Niehues🇬🇧 · D. M. Walker🇬🇧
The production of jets in charged current deep inelastic scattering (CC DIS) constitutes a class of observables that can be used to simultaneously test perturbative predictions for the strong and the electroweak sectors of the Standard Model. We compute both single jet and di-jet production in CC DIS for the first time at next-to-next-to-leading order (NNLO) in the strong coupling. Our computation is fully differential in the jet and lepton kinematics, and we observe a substantial reduction of scale variation uncertainties in the NNLO predictions compared to next-to-leading order (NLO). Our calculation will prove essential for full exploitation of data at a possible future LHeC collider.
hep-phPLB(2019)·19 citations
15*
The Supersymmetric R-Parity Violating Dine-Fischler-Srednicki-Zhitnitsky Axion Model
Stefano Colucci🇩🇪 · Herbi K. Dreiner🇩🇪 · Lorenzo Ubaldi🇮🇹
We propose a complete R-parity violating supersymmetric model with baryon triality that contains a Dine-Fischler-Srednicki-Zhitnitsky axion chiral superfield. We parametrize supersymmetry breaking with soft terms, and determine under which conditions the model is cosmologically viable. As expected we always find a region of parameter space in which the axion is a cold dark matter candidate. The mass of the axino, the fermionic partner of the axion, is controlled by a Yukawa coupling. When heavy [ $O$ (TeV)], the axino decays early and poses no cosmological problems. When light [ $O$ (keV)] it can be long lived and a warm dark matter candidate. We concentrate on the latter case and study in detail the decay modes of the axino. We find that constraints from astrophysical X- and gamma rays on the decay into photon and neutrino can set new bounds on some trilinear supersymmetric R-parity violating Yukawa couplings. In some corners of the parameter space the decays of a relic axino can also explain a putative 3.5 keV line.
hep-phPRD(2019)·13 citations
16*
Emerging chromo-natural inflation
Valerie Domcke🇩🇪 · Ben Mares🇮🇹 · Francesco Muia🇮🇹 · Mauro Pieroni🇪🇸
The shift-symmetric coupling of a pseudo-scalar particle driving inflation to gauge fields provides a unique way of probing cosmic inflation. We show for an SU(2) gauge group how a classical isotropic background gauge field develops from the standard quantum mechanical vacuum in the far past. Over the course of inflation, the theory dynamically evolves from an approximately abelian regime into an inherently non-abelian regime, with distinct predictions for the scalar and tensor power spectra. The latter regime closely resembles a setup known as chromo-natural inflation, although our main focus here is on a new part of the parameter space which has received little attention so far. For single-field slow roll inflation models, large scales may exit the horizon in the abelian regime, ensuring agreement with the observations of the anisotropies in the cosmic microwave background, whereas smaller scales experience the non-abelian effects. This results in a strong enhancement of the stochastic gravitational wave background at small scales, e.g. at frequencies accessible with ground-based interferometers. For the scalar power spectrum, a similar enhancement arises due to non-linear contributions.
hep-phastro-ph.COgr-qchep-thJCAP(2019)·67 citations
17*
Affine-Goldstone/quartet-metric gravity: emergent vs. existent
Yury F. Pirogov🇷🇺
As a group-theoretic foundation of gravity, it is considered an affine-Goldstone nonlinear model based upon the nonlinear realization of the global affine symmetry spontaneously broken at the Planck scale to the Poincare symmetry. It is shown that below this scale the model justifies and elaborates an earlier introduced effective field theory of the quartet-metric gravity incorporating the gravitational dark substances emerging in addition to the tensor graviton. The prospects for subsequent going beyond the nonlinear model above the Planck scale are indicated.
↳ gr-qchep-phPhys.Atom.Nucl.(2019)·1 citation
18*
Identifying rotation in SASI-dominated core-collapse supernovae with a neutrino gyroscope
Laurie Walk🇩🇰 · Irene Tamborra (Niels Bohr Institute)🇩🇰 · Hans-Thomas Janka🇩🇪 · Alexander Summa (MPA, Garching)🇩🇪
Measuring the rotation of core-collapse supernovae (SN) and of their progenitor stars is extremely challenging. Here it is demonstrated that neutrinos may potentially be employed as stellar gyroscopes, if phases of activity by the standing accretion-shock instability (SASI) affect the neutrino emission prior to the onset of the SN explosion. This is shown by comparing the neutrino emission properties of self-consistent, three-dimensional (3D) SN simulations of a 15 M_sun progenitor without rotation as well as slow and fast rotation compatible with observational constraints. The explosion of the fast rotating model gives rise to long-lasting, massive polar accretion downflows with stochastic time-variability, detectable e.g. by the IceCube Neutrino Observatory for any observer direction. While spectrograms of the neutrino event rate of non-rotating SNe feature a well-known sharp peak due to SASI for observers located in the proximity of the SASI plane, the corresponding spectrograms of rotating models show activity over a wide range of frequencies, most notably above 200 Hz for rapid rotation. In addition, the Fourier power spectra of the event rate for rotating models exhibit a SASI peak with lower power than in non-rotating models. The spectra for the rotating models also show secondary peaks at higher frequencies with greater relative heights compared to the main SASI peak than for non-rotating cases. These rotational imprints will be detectable for SNe at 10 kpc or closer.
↳ astro-ph.HEhep-phPRD(2018)·39 citations
19*
Stable finite energy global vortices and asymptotic freedom
D. Bazeia🇧🇷 · M.A. Marques🇧🇷 · R. Menezes🇧🇷
This work deals with global vortices in the three-dimensional spacetime. We study the case of a simple model with $U (1)$ symmetry and find a way to describe stable, finite energy global vortices. The price we pay to stabilize the solution is the presence of scale invariance, but we have found a way to trade it with an electric charge in a medium with generalized permittivity, which is further used to capture the basic feature of asymptotic freedom.
↳ hep-thhep-phEPL(2018)·5 citations
20*
Latest predictions from the EbyE NLO EKRT model
Harri Niemi🇫🇮 · Kari J. Eskola🇫🇮 · Risto Paatelainen🇫🇮 · Kimmo Tuominen🇫🇮
We present the latest results from the NLO pQCD + saturation + viscous hydrodynamics (EbyE NLO EKRT) model. The parameters in the EKRT saturation model are fixed by the charged hadron multiplicity in the 0-5 \% 2.76 TeV Pb+Pb collisions. The $s$ , $A$ and centrality dependence of the initial particle production follows then from the QCD dynamics of the model. This allows us to predict the $s$ and $A$ dependence of the particle production. We show that our results are in an excellent agreement with the low- $p_{T}$ data from 2.76 TeV and 5.02 TeV Pb+Pb collisions at the LHC as well as with the data from the 200 GeV Au+Au collisions at RHIC. In particular, we study the centrality dependences of hadronic multiplicities, flow coefficients, and various flow correlations. Furthermore, the nuclear mass number dependence of the initial particle production and hydrodynamic evolution can be tested in the 5.44 TeV Xe+Xe collisions at the LHC. To this end, we show our predictions for charged particle multiplicities, and in particular, show how the deformations of the Xe nuclei reflect into the flow coefficients.
↳ nucl-thhep-phNPA(2019)·5 citations
21*
Top-Quark Physics at the CLIC Electron-Positron Linear Collider
H. Abramowicz🇮🇱 · N. Alipour Tehrani🇨🇭 · D. Arominski · Y. Benhammou🇮🇱 · M. Benoit🇨🇭 · J.-J. Blaising🇫🇷 · M. Boronat🇪🇸 · O. Borysov🇮🇱 · R.R. Bosley🇬🇧 · I. Božović Jelisavčić🇷🇸 · I. Boyko🇷🇺 · S. Brass🇩🇪 and 105 other authors
The Compact Linear Collider (CLIC) is a proposed future high-luminosity linear electron-positron collider operating at three energy stages, with nominal centre-of-mass energies: 380 GeV, 1.5 TeV, and 3 TeV. Its aim is to explore the energy frontier, providing sensitivity to physics beyond the Standard Model (BSM) and precision measurements of Standard Model processes with an emphasis on Higgs boson and top-quark physics. The opportunities for top-quark physics at CLIC are discussed in this paper. The initial stage of operation focuses on top-quark pair production measurements, as well as the search for rare flavour-changing neutral current (FCNC) top-quark decays. It also includes a top-quark pair production threshold scan around 350 GeV which provides a precise measurement of the top-quark mass in a well-defined theoretical framework. At the higher-energy stages, studies are made of top-quark pairs produced in association with other particles. A study of ttH production including the extraction of the top Yukawa coupling is presented as well as a study of vector boson fusion (VBF) production, which gives direct access to high-energy electroweak interactions. Operation above 1 TeV leads to more highly collimated jet environments where dedicated methods are used to analyse the jet constituents. These techniques enable studies of the top-quark pair production, and hence the sensitivity to BSM physics, to be extended to higher energies. This paper also includes phenomenological interpretations that may be performed using the results from the extensive top-quark physics programme at CLIC.
↳ hep-exhep-phJHEP(2019)·165 citations
22*
A retrospective look at Regge poles
Alessandro Bottino🇮🇹
The theoretical motivations that led Tullio Regge to investigate the analytical properties of the scattering amplitude of the collision process between two particles in terms of complex energy and complex angular momentum are briefly reviewed and set in the context of the S-matrix theory that was developed in the late Fifties and early Sixties of the last century, in an attempt to unravel the properties of the strong interaction.
↳ physics.hist-phhep-phhep-thAtti Accad. Sci. Torino, Cl. Sci. Fis. Mat. Nat.(2018)·2 citations
23*
Inferred Evidence For Dark Matter Kinematic Substructure with SDSS-Gaia
Lina Necib🇺🇸 · Mariangela Lisanti🇺🇸 · Vasily Belokurov🇬🇧
We use the distribution of accreted stars in SDSS-Gaia DR2 to demonstrate that a non-trivial fraction of the dark matter halo within Galactocentric radii of 7.5-10 kpc and $∣ z ∣ > 2.5$ kpc is in substructure, and thus may not be in equilibrium. Using a mixture likelihood analysis, we separate the contributions of an old, isotropic stellar halo and a younger anisotropic population. The latter dominates and is uniform within the region studied. It can be explained as the tidal debris of a disrupted massive satellite on a highly radial orbit, and is consistent with mounting evidence from recent studies. Simulations that track the tidal debris from such mergers find that the dark matter traces the kinematics of its stellar counterpart. If so, our results indicate that a component of the nearby dark matter halo that is sourced by luminous satellites is in kinematic substructure referred to as debris flow. These results challenge the Standard Halo Model, which is discrepant with the distribution recovered from the stellar data, and have important ramifications for the interpretation of direct detection experiments.
↳ astro-ph.GAastro-ph.COhep-ph123 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.