HEP Phenomenology·hep-ph

Tue·Apr 16, 2019Tuesday·April 16, 2019

40 papers—30 primary·10 cross-listed·reconstructed*

01*
Jet Structure Studies in Small Systems
Z. Varga🇭🇺 · R. Vertesi🇭🇺 · G. G. Barnafoldi🇭🇺
A study investigating a possible jet shape dependence on the charged event multiplicity was performed on collision samples generated by Monte-Carlo (MC) event generators PYTHIA and HIJING++. We calculated the integral jet shape and found a significant modification caused by multiple-parton interactions. By interchanging and enabling different model ingredients in the simulations and analyzing the results in several $p_{T}$ bins and event multiplicity classes, we found a characteristic jet size measure that was independent of the chosen tunes, settings, and jet reconstruction algorithms.
hep-phnucl-exUniverse(2019)·8 citations
02*
The $W γ$ decay of the elusive charged Higgs boson in the two-Higgs-doublet model with vectorlike fermions
Jeonghyeon Song🇰🇷 · Yeo Woong Yoon🇰🇷
The LHC search for the charged Higgs boson in the intermediate-mass range ( $M_{H^{\pm}} \sim m_{t}$ ) is actively being performed after the next-to-leading order calculation of the total production cross section of $pp \to H^{\pm} W^{\mp} b b ˉ$ . In the decay part, only the $τ ν$ mode is mainly concerned because of the experimental difficulty in the $t b$ mode. In the framework of a two-Higgs-doublet model, we suggest that the $W γ$ channel can be helpful in probing this charged Higgs boson, if introducing vectorlike fermions. In type-I-II model where the SM fermions are assigned in type-I while the vectorlike fermions are in type-II, the branching ratio is greatly enhanced up to $\sim O (0.01)$ in a large portion of the parameter space allowed by the Higgs precision data, the electroweak oblique parameters, and the direct search bounds at the LHC. Two kinds of production channels, $g g \to H^{\pm} W^{\mp} b b ˉ$ and $g g \to H / A \to H^{\pm} W^{\mp}$ , are also studied. We find that the signal rate $σ \times B (W γ)$ is quite sizable, more than 10 fb in some parameter space.
hep-phhep-exPRD(2019)·23 citations
03*
A possible explanation of the threshold enhancement in the process $e^{+} e^{-} \to Λ Λ ˉ$
Li-Ye Xiao🇨🇳 · Xin-Zhen Weng🇨🇳 · Xian-Hui Zhong🇨🇳 · Shi-Lin Zhu🇨🇳
Inspired by the recent measurement of the process $e^{+} e^{-} \to Λ Λ ˉ$ , we calculate the mass spectrum of the $ϕ$ meson with the GI model. For the excited vector strangeonium states $ϕ (3 S, 4 S, 5 S, 6 S)$ and $ϕ (2 D, 3 D, 4 D, 5 D)$ , we further investigate the electronic decay width with the Van Royen-Weisskopf formula, and the partial widths of the $Λ Λ ˉ$ , $Ξ^{- (*)} Ξ ˉ^{+}$ , and $Σ^{+ (*)} Σ ˉ^{- (*)}$ decay modes with the extended quark pair creation model. We find that the electronic decay width of the $D$ -wave vector strangeonium is about $3 \sim 8$ times larger than that of the $S$ -wave vector strangeonium. Around 2232 MeV the partial decay width of the $Λ Λ ˉ$ mode can reach up to several MeV for $ϕ (3^{3} S_{1})$ , while the partial $Λ Λ ˉ$ decay width of $ϕ (2^{3} D_{1})$ is $O (1 0^{- 3})$ keV. If the threshold enhancement reported by the BESIII Collaboration arises from the strangeonium meson, this state is very likely to be the $ϕ (3^{3} S_{1})$ state. We also note that the $Λ Λ ˉ$ and $Σ^{+} Σ ˉ^{-}$ partial decay widths of the states $ϕ (3^{3} D_{1})$ and $ϕ (4^{3} S_{1})$ are about several MeV, respectively, which are enough to be observed in future experiments.
hep-phCPC(2019)·26 citations
04*
Production of the $D_{s 0} (2317)$ and $D_{s 1} (2460)$ by kaon-induced reactions on a proton target
HongQiang Zhu🇨🇳 · Yin Huang🇨🇳
We investigate the possibility to study the charmed-strange mesons $D_{s 0} (2317)$ and $D_{s 1} (2460)$ by kaon-induced reactions on a proton target in an effective Lagrangian approach. The production process is described by the $t$ -channel $D^{0}$ and $D^{* 0}$ exchanges, respectively. Our theoretical approach is based on the chiral unitary theory where the $D_{s 0} (2317)$ and $D_{s 1} (2460)$ resonances are dynamically generated. Within the coupling constants of the $D_{s 0} (2317)$ to $K D$ and $D_{s 1} (2460)$ to $K D^{*}$ channels obtained from the chiral unitary theory, the total and differential cross sections of the $K^{-} p \to Λ_{c} D_{s 0} (2317)$ and $K^{-} p \to Λ_{c} D_{s 1} (2460)$ are evaluated. The $K ˉ p$ initial state interaction mediated by Pomeron and Reggeon exchanges is also included, which reduces the production cross sections of the $D_{s 0} (2317)$ and $D_{s 1} (2460)$ . If measured in future experiments, the predicted total cross sections and specific features of the angular distributions can be used to test the (molecular) nature of the $D_{s 0} (2317)$ and $D_{s 1} (2460)$ .
hep-phPRD(2019)·12 citations
05*
Theory Review of Neutrino Models and CP Violation
Stephen F King🇬🇧
Although the measurement of the reactor angle has killed tribimaximal lepton mixing, its descendants survive with charged lepton corrections, or in less constrained forms such as trimaximal mixing and/or mu-tau symmetry, each with characteristic predictions. Such patterns may be enforced by a remnant of some non-Abelian discrete family symmetry, possibly together with a generalised CP symmetry, which could originate from continuous gauge symmetry and/or superstring theory in compactified extra dimensions, as a finite subgroup of the modular symmetry.
hep-ph7 citations
06*
Probing anomalous gauge-Higgs couplings using $Z$ boson polarization at $e^{+} e^{-}$ colliders
Kumar Rao🇮🇳 · Saurabh D. Rindani🇮🇳 · Priyanka Sarmah🇮🇳
We study possible new physics interactions in the $Z Z H$ vertex contributing to the Higgsstrahlung process $e^{+} e^{-} \to Z H$ at proposed future $e^{+} e^{-}$ colliders using the polarization of the $Z$ as a probe. We calculate the spin density matrix of the $Z$ for the process and determine the eight independent polarization parameters of the $Z$ boson which have the potential to constrain the anomalous couplings. We study angular asymmetries using the decay leptons from the $Z$ boson which are simply related to the polarization observables. We also estimate the limits that can be placed on the anomalous couplings using measurements of these angular asymmetries at centre of mass energies of 250 GeV and 500 GeV and various combinations of polarized $e^{+}$ and $e^{-}$ beams.
hep-phNPB(2020)·16 citations
07*
Off-shell renormalization in the presence of dimension 6 derivative operators. I. General theory
Daniele Binosi🇮🇹 · Andrea Quadri🇮🇹
The consistent recursive subtraction of UV divergences order by order in the loop expansion for spontaneously broken effective field theories with dimension-6 derivative operators is presented for an Abelian gauge group. We solve the Slavnov-Taylor identity to all orders in the loop expansion by homotopy techniques and a suitable choice of invariant field coordinates (named bleached variables) for the linearly realized gauge group. This allows one to disentangle the gauge-invariant contributions to off-shell 1-PI amplitudes from those associated with the gauge-fixing and (generalized) non-polynomial field redefinitions (that do appear already at one loop). The tools presented can be easily generalized to the non-Abelian case.
hep-phhep-thJHEP(2019)·12 citations
08*
Off-shell renormalization in the presence of dimension 6 derivative operators. II. UV coefficients
Daniele Binosi🇮🇹 · Andrea Quadri🇮🇹
The full off-shell one loop renormalization for all divergent amplitudes up to dimension 6 in the Abelian Higgs-Kibble model, supplemented with a maximally power counting violating higher-dimensional gauge-invariant derivative interaction $\sim g ϕ^{†} ϕ (D^{μ} ϕ)^{†} D_{μ} ϕ$ , is presented. This allows one to perform the complete renormalization of radiatively generated dimension 6 operators in the model at hand. We describe in details the technical tools required in order to disentangle the contribution to UV divergences parameterized by (generalized) non-polynomial field redefinitions. We also discuss how to extract the dependence of the $β$ -function coefficients on the non-renormalizable coupling $g$ in one loop approximation, as well as the cohomological techniques (contractible pairs) required to efficiently separate the mixing of contributions associated to different higher-dimensional operators in a spontaneously broken effective field theory.
hep-phhep-thEPJC(2020)·11 citations
09*
Quartic Coupling Unification in the Maximally Symmetric 2HDM
Neda Darvishi🇬🇧 · Apostolos Pilaftsis🇬🇧
We consider the Maximally Symmetric Two-Higgs Doublet Model (MS-2HDM) in which the so-called Standard Model (SM) alignment can be naturally realised as a consequence of an accidental SO(5) symmetry in the Higgs sector. This symmetry is broken (i) explicitly by renormalization-group (RG) effects and (ii) softly by the bilinear scalar mass term $m_{12}^{2}$ . We find that in the MS-2HDM all quartic couplings can unify at large RG scales $μ_{X} \sim 1 0^{11}$ - $1 0^{20}$ GeV. In particular, we show that quartic coupling unification can take place in two different conformally invariant points, where all quartic couplings vanish. We perform a vacuum stability analysis of the model in order to ensure that the electro-weak vacuum is sufficiently long-lived. The MS-2HDM is a minimal and very predictive extension of the SM governed by only three additional parameters: the unification scale $μ_{X}$ , the charged Higgs mass $M_{h^{\pm}}$ (or $m_{12}^{2}$ ) and $tan β$ , which allow one to determine the entire Higgs sector of the model. In terms of these input parameters, we present illustrative predictions of misalignment for the SM-like Higgs-boson couplings to the $W^{\pm}$ and $Z$ bosons and, for the first time, to the top and bottom quarks.
hep-phPRD(2019)·31 citations
10*
$B_{c}$ excitations at LHC experiments
A. V. Berezhnoy🇷🇺 · I. N. Belov🇷🇺 · A. K. Likhoded🇷🇺 · A. V. Luchinsky
The $2 S$ $B_{c}$ states observed by ATLAS, CMS and LHCb Collaborations are discussed. The observation perspectives of $B_{c}^{*}$ , $2 P$ wave, $3 P$ wave and $D$ wave states of $B_{c}$ at LHC experiments are estimated.
hep-phMod.Phys.Lett.A(2019)·21 citations
11*
Dramatic implications of unitarity for meson spectroscopy
George Rupp🇵🇹 · Eef van Beveren🇵🇹
An unambiguous definition of meson resonance masses requires a description of the associated phase shifts in terms of a manifestly unitary $S$ -matrix and its complex poles. However, the commonly used Breit-Wigner (BW) parametrisations can lead to appreciable deviations. We demonstrate this for a simple elastic resonance, viz. $ρ (770)$ , whose pole and BW masses turn out to differ by almost 5 MeV. In the case of the very broad $f_{0} (500)$ and $K_{0}^{⋆} (700)$ scalar mesons, the discrepancies are shown to become much larger, while also putting question marks at the listed PDG BW masses and widths. Furthermore, some results are reviewed of a manifestly unitary model for meson spectroscopy, which highlight the potentially huge deviations from static model predictions. Finally, a related unitary model for production amplitudes is shown to explain several meson enhancements as non-resonant threshold effects, with profound implications for spectroscopy.
hep-phhep-exActa Phys.Polon.Supp.(2020)·1 citation
12*
A bound on Planck-scale deformations of CPT from muon lifetime
Michele Arzano🇮🇹 · Jerzy Kowalski-Glikman🇵🇱 · Wojciech Wislicki🇵🇱
We show that deformed relativistic kinematics, expected to emerge in a flat-spacetime limit of quantum gravity, predicts different lifetimes for particles and their antiparticles. This phenomenon is a consequence of Planck-scale modifications of the action of discrete symmetries. In particular we focus on deformations of the action of CPT derived from the kappa-Poincare algebra, the most studied example of Planck-scale deformation of relativistic symmetries. Looking at lifetimes of muons and anti-muons we are able to derive an experimental bound on the deformation parameter of kappa > 4x10^14 GeV from measurements at the LHC. Such bound has the potential to reach the value of kappa > 2x10^16 GeV using measurements at the planned Future Circular Collider (FCC).
hep-phgr-qchep-thPLB(2019)·22 citations
13*
On the two-body decay processes of the predicted three-body $K^{*} (4307)$ resonance
Xiu-Lei Ren🇩🇪 · Brenda B. Malabarba🇧🇷 · K. P. Khemchandani🇧🇷 · A. Martinez Torres🇧🇷
In a recent theoretical work, Phys. Lett. B785, 112 (2018), we proposed that a $K^{*}$ resonance with hidden charm content arises from the $K D D ˉ^{*}$ dynamics, where the $D D ˉ^{*}$ system is treated as a $Z_{c} (3900)$ or $X (3872)$ . With the motivation of determining its further properties, which can be observed in experiments, we now present a calculation of the decay processes of this $K^{*}$ , namely $K^{*} (4307)$ , to two-body channels. Particularly, we consider the decay channels $J / ψ K^{*} (892)$ , $D ˉ D_{s}$ , $D ˉ D_{s}^{*}$ and $D ˉ^{*} D_{s}^{*}$ . The mechanisms of the decay to these channels involve triangular loops and are a consequence of the internal structure of the state. Thus, the values found for the decay widths of the proposed $K^{*} (4307)$ are related to its nature and should be valuable for carrying on an experimental study of the $K^{*} (4307)$ . A $K^{*}$ state with such a mass (in the charmonium region) and quantum numbers is a clear manifestation of an exotic meson, since, having hidden charm (i.e., a $c c ˉ$ pair), its mass and quantum numbers can not be explained within a quark-antiquark description.
hep-phnucl-thJHEP(2019)·14 citations
14*
Improved Constraints on Sterile Neutrinos in the MeV to GeV Mass Range
D. A. Bryman🇨🇦 · R. Shrock🇺🇸
Improved upper bounds are presented on the coupling $∣ U_{e 4} ∣^{2}$ of an electron to a sterile neutrino $ν_{4}$ from analyses of data on nuclear and particle decays, including superallowed nuclear beta decays, the ratios $R_{e / μ}^{(π)} = B R (π^{+} \to e^{+} ν_{e}) / B R (π^{+} \to μ^{+} ν_{μ})$ , $R_{e / μ}^{(K)}$ , $R_{e / τ}^{(D_{s})}$ , and $B_{e 2}^{+}$ decay, covering the mass range from MeV to GeV.
hep-phhep-exnucl-thPRD(2019)·75 citations
15*
Sivers distribution functions of sea quark in proton with chiral Lagrangian
Fangcheng He🇨🇳 · P. Wang🇨🇳
We propose a mechanism for the Sivers distribution function in proton with chiral Lagrangian. By introducing the gauge link of the vector meson, the transverse momentum dependent distribution of a pion in the nucleon is re-defined which is locally $S U (2)_{V}$ invariant as the Lagrangian. The eikonal propagator is generated from the gauge link and this scenario is proved to be equivalent to the final state interaction. By combining the calculated splitting function and the valence $q ˉ$ distribution in $π$ from the recent fit, the sea quark Sivers function in proton is obtained. We find reasonable numerical results for the first momentum $x Δ^{N} f_{q ˉ}^{(1)} (x)$ without any fine tuning of the free parameters.
hep-phPRD(2019)·18 citations
16*
Is Symmetry Breaking into Special Subgroup Special?
Taichiro Kugo🇯🇵 · Naoki Yamatsu🇯🇵
The purpose of this paper is to show that the symmetry breaking into special subgroups is not special at all, contrary to the usual wisdom. To demonstrate this explicitly, we examine dynamical symmetry breaking pattern in 4D $S U (N)$ Nambu--Jona-Lasinio type models in which the fermion matter belongs to an irreducible representation of $S U (N)$ . The potential analysis shows that for almost all cases at the potential minimum the $S U (N)$ group symmetry is broken to its special subgroups such as $S O (N)$ or $U S p (N)$ when symmetry breaking occurs.
hep-phhep-thPTEP(2019)·4 citations
17*
The Higgs Profile in the Standard Model and Beyond
J. Lorenzo Diaz-Cruz🇲🇽
We present a review of Higgs physics in the SM and beyond, including the tests of the Higgs boson properties that have been performed at LHC and have permitted to delineate its profile. After presenting the essential features of the BEH mechanism, and its implementation in the SM, we discuss how the Higgs mass limits developed over the years. These constraints in turn helped to classify the Higgs phenomenology (decays and production mechanisms), which provided the right direction to search for the Higgs particle, an enterprise that culminated with its discovery at LHC. So far, the constraints on the couplings of the Higgs particle, point towards a SM interpretation. However, the SM has open ends that suggest the need to look for extensions of the model. We discuss in general the connection of the Higgs sector with some new physics (e.g. supersymmetry, flavor and Dark matter), with special focus on a more flavored Higgs sector. Thus is realized in the most general 2HDM, and its textured version, which we study in general, and for its various limits, which contain distinctive flavor-violating signals that could be searched at current and future colliders.
hep-phRev.Mex.Fis.(2019)·19 citations
18*
Monopoles, Strings, and Necklaces in $S O (10)$ and $E_{6}$
G. Lazarides🇬🇷 · Q. Shafi🇺🇸
We employ a variety of symmetry breaking patterns in $S O (10)$ and $E_{6}$ Grand Unified Theories to demonstrate the appearance of topological defects including magnetic monopoles, strings, and necklaces. We show that independent of the symmetry breaking pattern, a topologically stable superheavy monopole carrying a single unit of Dirac charge as well as color magnetic charge is always present. Lighter intermediate mass topologically stable monopoles carrying two or three quanta of Dirac charge can appear in $S O (10)$ and $E_{6}$ models respectively. These lighter monopoles as well as topologically stable intermediate scale strings can survive an inflationary epoch. We also show the appearance of a novel necklace configuration in $S O (10)$ broken to the Standard Model via $S U (4)_{c} \times S U (2)_{L} \times S U (2)_{R}$ . It consists of $S U (4)_{c}$ and $S U (2)_{R}$ monopoles connected by flux tubes. Necklaces consisting of monopoles and antimonopoles joined together by flux tubes are also identified. Even in the absence of topologically stable strings, a monopole-string system can temporarily appear. This system decays by emitting gravity waves and we provide an example in which the spectrum of these waves is strongly peaked around $1 0^{- 4} Hz$ with $Ω_{gw} h^{2} ≃ 1 0^{- 12}$ . This spectrum should be within the detection capability of LISA.
hep-phhep-thJHEP(2019)·54 citations
19*
Wiedemann-Franz Law For Hot QCD Matter in a Color String Percolation Scenario
Pragati Sahoo🇮🇳 · Raghunath Sahoo🇮🇳 · Swatantra Kumar Tiwari🇮🇳
Transport coefficients serve as important probes in characterizing the QCD matter created in high-energy heavy-ion collisions. Thermal and electrical conductivities as transport coefficients have got special significance in studying the time evolution of the created matter. We have adopted color string percolation approach for the estimation of thermal conductivity ( $κ$ ), electrical conductivity ( $σ_{e l}$ ) and their ratio, which is popularly known as Wiedemann-Franz law in condensed matter physics. The ratio $κ / σ_{e l} T$ , which is also known as Lorenz number ( $L$ ) is studied as a function of temperature and is compared with various theoretical calculations. We observe that the thermal conductivity for hot QCD medium is almost temperature independent in the present formalism and matches with the results obtained in ideal equation of state (EOS) for quark-gluon plasma with fixed coupling constant ( $α_{s}$ ). The obtained Lorenz number is compared with the Stefan-Boltzmann limit for an ideal gas. We observe that a hot QCD medium with color degrees of freedom behaves like a free electron gas.
hep-phnucl-thPRD(2019)·13 citations
20*
Analysis of the anomalous quartic $W W W W$ couplings at the LHeC and the FCC-he
E. Gurkanli🇹🇷 · V. Ari🇹🇷 · A. A. Billur🇹🇷 · M. Köksal🇹🇷
The quartic gauge boson couplings that identify the strengths of the gauge boson self-interactions are exactly determined by the non-Abelian gauge nature of the Standard Model. The examination of these couplings at $e p$ collisions with high center-of-mass energy and high integrated luminosity provides an important opportunity to test the validity of the Standard Model and the existence of new physics beyond the Standard Model. The quartic gauge boson couplings can contribute directly to multi-boson production at colliders. Therefore, we examine the potential of the process $e p \to ν_{e} W^{+} W^{-} j$ at the Large Hadron Electron Collider and the Future Circular Collider-hadron electron to study non-standard $W W W W$ couplings in a model independent way by means of the effective Lagrangian approach. We present an investigation on measuring $W^{+} W^{-}$ production in pure leptonic and semileptonic decay channels. In addition, we calculate the sensitivity limits at $95%$ Confidence Level on the anomalous $\frac{f _{M 0}}{Λ ^{4}}$ , $\frac{f _{M 1}}{Λ ^{4}}$ , $\frac{f _{M 7}}{Λ ^{4}}$ , $\frac{f _{S 0}}{Λ ^{4}}$ , $\frac{f _{S 1}}{Λ ^{4}}$ , $\frac{f _{T 0}}{Λ ^{4}}$ , $\frac{f _{T 1}}{Λ ^{4}}$ and $\frac{f _{T 2}}{Λ ^{4}}$ couplings obtained by dimension-8 operators through the process $e p \to ν_{e} W^{+} W^{-} j$ for the Large Hadron Electron Collider and the Future Circular Hadron Electron Collider's different center-of-mass energies and integrated luminosities. Our results show that with the process $e p \to ν_{e} W^{+} W^{-} j$ at the Large Hadron Electron Collider and the Future Circular Collider-hadron electron the sensitivity estimated on the anomalous $W W W W$ couplings can be importantly strengthened.
hep-phEur.Phys.J.Plus(2021)·0 citations
21*
The Neutrino Option
Ilaria Brivio🇩🇰
The Neutrino Option is a scenario where the Higgs mass is generated at the same time as neutrino masses in the type-I seesaw model. This framework provides a dynamical origin for the scalar potential of the Standard Model and suggests a new approach to the hierarchy problem. Here we review the preliminary analysis of Ref. [1], that showed the viability of this scenario, as well as the improved study of Ref. [2], that led to a better identification of the region of the parameter space where the Neutrino Option can be realized. We find that experimental constraints from both Higgs and neutrino physics can be accommodated introducing 2 heavy Majorana neutrinos with mass $M_{1} ≃ M_{2} \sim 0.5 - 10$ PeV and Yukawa couplings to the lepton doublet of order $1 0^{- 4} - 1 0^{- 2}$ , assuming that at the scale $M$ the classical Higgs potential is approximately conformal, with a quartic Higgs coupling $λ_{0} \sim 0.01 - 0.05$ . Specifying the light neutrino mass ordering, the ratio $M_{2} / M_{1}$ or a given value of the top quark mass identifies narrower ranges for all the parameters. Although no further signature of the Neutrino Option is generally predicted at the currently accessible energy scales, conformal UV completions have been proposed, that could be tested e.g. via detection of gravitational waves. Leptogenesis can also be successfully realized in this scenario, that intriguingly ties together the breaking of the conformal and electroweak symmetries with the violation of lepton number.
hep-ph0 citations
22*
New model for radiatively generated Dirac neutrino masses and lepton flavor violating decays of the Higgs boson
Kazuki Enomoto🇯🇵 · Shinya Kanemura🇯🇵 · Kodai Sakurai🇩🇪 · Hiroaki Sugiyama🇯🇵
We propose a new mechanism to explain neutrino masses with lepton number conservation, in which the Dirac neutrino masses are generated at the two-loop level involving a dark matter candidate. In this model, branching ratios of lepton flavor violating decays of the Higgs boson can be much larger than those of lepton flavor violating decays of charged leptons. If lepton flavor violating decays of the Higgs boson are observed at future collider experiments without detecting lepton flavor violating decays of charged leptons, most of the models previously proposed for tiny neutrino masses are excluded while our model can still survive. We show that the model can be viable under constraints from current data for neutrino experiments, searches for lepton flavor violating decays of charged leptons and dark matter experiments.
hep-phPRD(2019)·22 citations
23*
Roles of sterile neutrinos in particle physics and cosmology
Sin Kyu Kang🇰🇷
The impacts of the light sterile neutrino hypothesis in particle physics and cosmology are reviewed. The observed short baseline neutrino anomalies challenging the standard explanation of neutrino oscillations within the framework of three active neutrinos are addressed. It is shown that they can be interpreted as the experimental hints pointing towards the existence of sterile neutrino at the eV scale. While the electron neutrino appearance and disappearance data are in favor of such a sterile neutrino, the muon disappearance data disfavor it, which gives rise to a strong appearance-disappearacne tension. After a brief review on the cosmological effects of light sterile neutrinos, proposed signatures of light sterile neutrinos in the existing cosmological data are discussed. The keV-scale sterile neutrinos as possible dark matter candidates are also discussed by reviewing different mechanisms of how they can be produced in the early Universe and how their properties can be constrained by several cosmological observations. We give an overview of the possibility that keV-scale sterile neutrino can be a good DM candidate and play a key role in achieving low scale leptogenesis simultaneously by introducing a model where an extra light sterile neutrino is added on top of type I seesaw model.
hep-phgr-qcInt.J.Mod.Phys.A(2019)·15 citations
24*
Baryon sigma terms in SU(3) BChPT x 1/Nc
Ishara P. Fernando🇺🇸 · Jose L. Goity🇺🇸
ChPT and the $1/ N_{c}$ expansion provide systematic frameworks for the strong interactions at low energy. A combined framework of both expansions has been developed and applied for baryons with three light-quark-flavors. The small scale expansion of the combined approach is identified as the $ξ$ -expansion, in which the power counting of the expansions is linked according to $O (p) = O (1/ N_{c}) = O (ξ)$ . The physical baryon masses as well as lattice QCD baryon masses for different quark mass masses are analyzed to $O (ξ^{3})$ in that framework. $σ$ terms are addressed using the Feynman Hellmann theorem. For the nucleon, a useful connection between the deviation of the Gell-Mann-Okubo relation and the $σ$ term $σ_{8 N}$ associated with the scalar density $u ˉ u + d ˉ d - 2 s ˉ s$ is identified. In particular, the deviation from the tree level relation $σ_{8 N} = \frac{1}{3} (2 m_{N} - m_{Σ} - m_{Ξ})$ , which gives rise to the so called $σ$ -term puzzle, is studied in the $ξ$ -expansion. A large correction non-analytic in $ξ$ results for that relation, making plausible the resolution of the puzzle. Issues with the determination of the strangeness $σ$ terms are discussed, emphasizing the need for lattice calculations at smaller $m_{s}$ for better understanding the range of validity of the effective theory. The analysis presented here leads to $σ_{π N} = 69 (10)$ ~MeV and $σ_{π Δ} = 60 (10)$ ~MeV.
hep-phnucl-thPoS(2019)·0 citations
25*
BChPT $\times 1/ N_{c}$ in SU(3): a more effective theory
Ishara P. Fernando🇺🇸 · Jose L. Goity🇺🇸
The chiral and $1/ N_{c}$ expansions are combined in the description of low energy baryons. The combination furnishes a better behaved expansion, consequence of exactly eliminating large terms that violate the $1/ N_{c}$ expansion and which are typical of formulations of BChPT where consistency with the large $N_{c}$ limit is disregarded. The improvements are particularly dramatic in the case of SU(3). The general framework is outlined and applications to the vector charges and axial couplings are presented along with a comparison with Lattice QCD results with three quark flavors.
hep-phPoS(2019)·1 citation
26*
Electron-interacting dark matter: Implications from DAMA/LIBRA-phase2 and prospects for liquid xenon detectors and NaI detectors
B. M. Roberts🇫🇷 · V. V. Flambaum🇦🇺
We investigate the possibility for the direct detection of low mass (GeV scale) WIMP dark matter in scintillation experiments. Such WIMPs are typically too light to leave appreciable nuclear recoils, but may be detected via their scattering off atomic electrons. In particular, the DAMA Collaboration [R. Bernabei et al., Nucl. Phys. At. Energy 19, 307 (2018)] has recently presented strong evidence of an annual modulation in the scintillation rate observed at energies as low as 1 keV. Despite a strong enhancement in the calculated event rate at low energies, we find that an interpretation in terms of electron-interacting WIMPs cannot be consistent with existing constraints. We also demonstrate the importance of correct treatment of the atomic wavefunctions, and show the resulting event rate is very sensitive to the low-energy performance of the detectors, meaning it is crucial that the detector uncertainties be taken into account. Finally, we demonstrate that the potential scintillation event rate can be much larger than may otherwise be expected, meaning that competitive searches can be performed for GeV scale WIMPs using the conventional prompt S1 scintillation signals. This is important given the recent and upcoming very large liquid xenon detectors.
hep-phastro-ph.COPRD(2019)·49 citations
27*
Optimization for factorized quantities in perturbative QCD
P. M. Stevenson🇺🇸
Perturbative calculations of factorized physical quantities, such as moments of structure functions, suffer from renormalization- and factorization-scheme dependence. The application of the principle of minimal sensitivity to "optimize" the scheme choices is reconsidered, correcting deficiencies in the earlier literature. The proper scheme variables, RG equations, and invariants are identified. Earlier results of Nakkagawa and Niegawa are recovered, even though their starting point is, at best, unnecessarily complicated. In particular, the optimized coefficients of the coefficient function C are shown to vanish, so that C^opt=1. The resulting simplifications mean that the optimization procedure is as simple as that for purely-perturbative physical quantities.
hep-phNPB(2019)·3 citations
28*
Majorana neutrinos with effective interactions in B decays
Lucía Duarte🇺🇾 · Javier Peressutti🇦🇷 · Ismael Romero🇦🇷 · Oscar A. Sampayo🇦🇷
We investigate the possible contribution of Majorana neutrinos to $B$ meson decays in an effective interaction formalism, in the mass range $0.5$ GeV $< m_{N} < 5$ GeV. We study the decay of the $B^{-}$ meson via $B^{-} \to μ^{-} μ^{-} π^{+}$ at LHCb, which is a signal for leptonic number violation and the presence of Majorana neutrinos, and put bounds on different new physics contributions, characterized by their Dirac-Lorentz structure. We also study the bounds imposed by the radiative $B$ decay ( $B^{-} \to μ^{-} ν γ$ ) results from Belle. The obtained bounds are more restrictive than previous values found for dimension 6 four-fermion contact vectorial and scalar Majorana neutrino interactions in the context of the Left-Right symmetric model for higher Majorana masses at the LHC, showing that the direct calculation of the effective $N$ interactions contribution to different processes can help to put more stringent bounds to different UV-complete models parameterized by an effective Lagrangian.
hep-phEPJC(2019)·14 citations
29*
Axion production and detection with superconducting RF cavities
Ryan Janish🇺🇸 · Vijay Narayan🇺🇸 · Surjeet Rajendran🇺🇸 · Paul Riggins🇺🇸
We propose a novel design of a laboratory search for axions based on photon regeneration with superconducting RF cavities. Our particular setup uses a toroid as a region of confined static magnetic field, while production and detection cavities are positioned in regions of vanishing external field. This permits cavity operation at quality factors of $Q \sim 1 0^{10} - 1 0^{12}$ . The limitations due to fundamental issues such as signal screening and back-reaction are discussed, and the optimal sensitivity is calculated. This experimental design can potentially probe axion-photon couplings beyond astrophysical limits, comparable and complementary to next generation optical experiments.
hep-phhep-exPRD(2019)·35 citations
30*
Exotic coloured fermions and lepton number violation at the LHC
E. Carquin🇨🇱 · J.C. Helo🇨🇱 · M. Hirsch🇪🇸 · N. A. Neill🇨🇱
Majorana neutrino mass models with a scale of lepton number violation (LNV) of order TeV potentially lead to signals at the LHC. Here, we consider an extension of the standard model with a coloured octet fermion and a scalar leptoquark. This model generates neutrino masses at 2-loop order. We make a detailed MonteCarlo study of the LNV signal at the LHC in this model, including a simulation of standard model backgrounds. Our forecast predicts that the LHC with 300/fb should be able to probe this model up to colour octet fermion masses in the range of (2.6-2.7) TeV, depending on the lepton flavour of the final state.
hep-phPRD(2019)·5 citations
31*
Complementarity of Stacking and Multiplet Constraints on the Blazar Contribution to the Cumulative High-Energy Neutrino Intensity
Chengchao Yuan🇺🇸 · Kohta Murase🇺🇸 · Peter Mészáros🇺🇸
We investigate the blazar contribution to the cumulative neutrino intensity assuming a generic relationship between neutrino and gamma-ray luminosities, $L_{ν} \propto (L_{ph})^{γ_{lw}}$ . Using the gamma-ray luminosity functions for blazars including flat spectrum radio quasars (FSRQs) and BL Lac objects, as well as the $F er mi$ -LAT detection efficiency, we estimate contributions from {blazars resolved by $F er mi$ -LAT as well as the unresolved counterpart.} Combining the existing upper limits from stacking analyses, the cumulative neutrino flux from all blazars ({including $F er mi$ -LAT resolved and unresolved ones}) are constrained { in the range $0 ≲ γ_{lw} ≲ 2.5$ }. We also evaluate the effects of the redshift evolution and the effective local number densities for each class of FSRQs, BL Lacs, and all blazars, by which we place another type of constraints on the blazar contribution using the non-detection of high-energy neutrino multiplets. We demonstrate that these two upper limits are complementary, and that the joint consideration of the stacking and multiplet analyses { not only supports the argument that blazars are disfavored as the dominant sources of the 100-TeV neutrino background, but it extends this argument by including also $F er mi$ -LAT-unresolved blazars as well, for a more generic luminosity correlation $L_{ν} \propto (L_{ph})^{γ_{lw}}$ }.
↳ astro-ph.HEhep-phApJ(2020)·53 citations
32*
Hydrodynamic flow in small systems, or: "How the heck is it possible that a system emitting only a dozen particles can be described by fluid dynamics?"
Ulrich W. Heinz (Ohio State University)🇺🇸 · J. Scott Moreland (Duke University)🇺🇸
The "unreasonable effectiveness" of relativistic fluid dynamics in describing high energy heavy-ion and even proton-proton collisions are demonstrated and discussed. Several recent ideas of optimizing relativistic fluid dynamics for the specific challenges posed by such collisions will be presented, and some thoughts will be offered why the framework works better than originally expected. I will also address the unresolved question where exactly hydrodynamics breaks down, and why.
↳ nucl-thhep-phnucl-exJ.Phys.Conf.Ser.(2019)·39 citations
33*
Stueckelberg breaking of Weyl conformal geometry with applications to gravity
D. M. Ghilencea🇷🇴
Weyl conformal geometry may play a role in early cosmology where effective theory at short distances becomes conformal. Weyl conformal geometry also has a built-in geometric Stueckelberg mechanism: it is broken spontaneously to Riemannian geometry after a Weyl gauge transformation (of "gauge fixing") while Stueckelberg mechanism re-arranges the degrees of freedom, conserving their number ( $n_{df}$ ). The Weyl gauge field ( $ω_{μ}$ ) of local scale transformations acquires a mass after absorbing a compensator (dilaton), decouples, and Weyl connection becomes Riemannian. Mass generation has thus a dynamic origin, as a transition from Weyl to Riemannian geometry. We show that a "gauge fixing" symmetry transformation of the original Weyl quadratic gravity action in its Weyl geometry formulation immediately gives the Einstein-Proca action for the Weyl gauge field and a positive cosmological constant, plus matter action (if present). As a result, the Planck scale is an {\it emergent} scale, where Weyl gauge symmetry is spontaneously broken and Einstein action is the broken phase of Weyl action. This is in contrast to local scale invariant models (no gauging) where a negative kinetic term (ghost dilaton) remains present and $n_{df}$ is not conserved when this symmetry is broken. The mass of $ω_{μ}$ , setting the non-metricity scale, can be much smaller than $M_{Planck}$ , for ultraweak values of the coupling ( $q$ ). If matter is present, a positive contribution to the Planck scale from a scalar field ( $ϕ_{1}$ ) vev induces a negative (mass) $^{2}$ term for $ϕ_{1}$ and spontaneous breaking of the symmetry under which it is charged. These results are immediate when using a Weyl geometry formulation of an action instead of its Riemannian picture. Briefly, Weyl gauge symmetry is physically relevant and its role in high scale physics should be reconsidered.
↳ hep-thgr-qchep-phPRD(2020)·78 citations
34*
Flux-tubes in confining gauge theories with gravitational dual
Vikram Vyas
The emergence of flux-tubes as the distance is increased between a quark and an antiquark is explored in a three-dimensional confining gauge theory using the gauge/gravity duality. We delineate the shape of the flux-tube corresponding to the classical open string in the bulk and further explore the fluctuation in its thickness induced by the fluctuation of the open string along the radial direction in the bulk. The relationship between the intrinsic shape of a flux-tube and its effect on the heavy quark potential is also discussed.
↳ hep-thhep-lathep-ph2 citations
35*
Axion Structure Formation II: The Wrath of Collapse
Erik W. Lentz🇩🇪 · Thomas R. Quinn🇺🇸 · Leslie J Rosenberg🇺🇸
The first paper in this series showed that QCD axion dark matter, as a highly-correlated Bose fluid, contains extra-classical physics on cosmological scales. The nature of the derived extra-classical physics is exchange-correlation interactions induced by the constraints of symmetric particle exchange and inter-axion correlations from self-gravitation. The paper also showed that the impact of extra-classical physics on early structure formation is marginal, as the exchange-correlation interaction is inherently non-linear. This paper continues the study of axion structure formation into the non-linear regime by now considering the case of full collapse and virialization. The N-body method is chosen to solve the collapse problem, and its algorithms are derived for a condensed Bose fluid. Simulations of isolated gravitational collapse are performed for both Bose and cold dark matter fluids using a prototype N-body code. Unique Bose structures are found to survive even the most violent collapses. Bose post-collapse features include dynamical changes to global structures, creation of new broad substructures, violations of classical binding energy conditions, and new fine structures. Effective models of the novel structures are constructed and possibilities for their discovery are discussed.
↳ astro-ph.COastro-ph.GAgr-qchep-phMNRAS(2020)·10 citations
36*
Resurgence, a problem of missing exponential corrections in asymptotic expansions
Ramon Miravitllas Mas🇪🇸
It is well known that perturbative expansions of path integrals are divergent. These expansions are to be understood as asymptotic expansions, which encode the limiting behaviour of the path integral for positive small coupling. Conventionally, the method of Borel summation assigns a finite answer to the divergent expansion. Still, the Borel sum might not encode the full information of a function, because it misses exponentially small corrections. In the present work, we consider a slight variation of the conventional Borel summation, in which a generalised Borel transform (an inverse Laplace transform) is followed by a directional Laplace transform. These new tools will allow us to give perhaps better answers to typical problems in Borel summation: missing exponential corrections and ambiguities in the Borel summation. In addition, we will define resurgence as a connection between the discontinuity of a function and the coefficients of its asymptotic expansion. From this definition, we will be able to reduce resurgence to the problem of missing exponential corrections in asymptotic expansions and understand, within a unified framework, different approaches to resurgence found in the literature.
↳ hep-thhep-ph3 citations
37*
Ultra-compact spherically symmetric dark matter charged star objects
Bartłomiej Kiczek🇵🇱 · Marek Rogatko🇵🇱
We study the properties of ultra-compact spherically symmetric dark matter sector star objects, being the solution of Einstein equations with two $U (1)$ -gauge fields. One of them is the ordinary Maxwell field, while the auxiliary gauge field pertains to the hidden sector, and mimics the properties of dark matter. The visible and hidden sectors are coupled by a kinetic mixing term with a coupling constant $α$ . We also investigate the possibility of condensation of charged scalar field around the reflecting dark matter star object. It happens that dark matter sector, both dark matter charge and coupling constant, cause shrinking of the star radius for which the condensation may occur.
↳ gr-qchep-phhep-thJCAP(2019)·16 citations
38*
On the Occurrence of Crossings Between the Angular Distributions of Electron Neutrinos and Antineutrinos in the Supernova Core
Shashank Shalgar🇩🇰 · Irene Tamborra🇩🇰
Neutrino fast pairwise conversions have been postulated to occur in the dense core of a core-collapse supernova (SN), possibly having dramatic consequences on the SN mechanism and the observable neutrino signal. One crucial condition favoring pairwise conversions is the presence of crossings between the electron neutrino and antineutrino angular distributions (i.e., electron neutrino lepton number crossings, ELN crossings). A stationary and spherically symmetric SN toy-model is constructed to reproduce the development of the neutrino angular distributions in the dense SN core in the absence of perturbations induced by hydrodynamical instabilities. By iteratively solving the neutrino Boltzmann equations including the collisional term, our model predicts that ELN crossings can develop only in the proximity of the decoupling region and for a sharp radial evolution of the baryon density, when the electron neutrino and antineutrino number densities are comparable. Such conditions are likely to occur only in the late SN stages. Interestingly, flavor instabilities induced by spatial or temporal perturbations are unlikely to generate ELN crossings dynamically within our simplified setup.
↳ astro-ph.HEhep-phApJ(2019)·63 citations
39*
Exploring the CMB Power Suppression in Canonical Inflation Models
Mark Gonzalez🇺🇸 · Mark P. Hertzberg🇺🇸
There exists some evidence of a suppression in power in the CMB multipoles around $l \sim 20 - 30$ . If taken seriously, this is in tension with the simplest inflationary models driven by a single scalar field with a standard type of slowly varying potential function $V (ϕ)$ . Such potential functions generate a nearly scale invariant spectrum and so they do not possess the requisite suppression in power. In this paper we explore if canonical two-derivative inflation models, with a step-like feature in the potential, can improve agreement with data. We find that improvement can be made when one utilizes the standard slow-roll approximation formula for the power spectrum. However, we find that in order to have a feature in the power spectrum that is sufficiently localized so as to not significantly disrupt higher $l$ or lower $l$ , the potential's step-like feature must be so sharp that the standard slow-roll approximations break down. This leads us to perform an exact computation of the power spectrum by solving for the Bunch-Davies mode functions numerically. We find that the corresponding CMB multipoles do not provide a good agreement with the data. We conclude that, unless there is fine-tuning, canonical inflation models do not fit this suppression in the data.
↳ astro-ph.COgr-qchep-phhep-thJCAP(2019)·1 citation
40*
Hidden Analytic Relations for Two-Loop Higgs Amplitudes in QCD
Qingjun Jin🇨🇳 · Gang Yang🇨🇳
We compute the Higgs plus two-quark and one-gluon amplitudes ( $H \to q q ˉ g$ ) and Higgs plus three-gluon amplitudes ( $H \to 3 g$ ) in the Higgs effective theory with a general class of operators. By changing the quadratic Casimir $C_{F}$ to $C_{A}$ , the maximally transcendental parts of the $H \to q q ˉ g$ amplitudes turn out to be equivalent to that of the $H \to 3 g$ amplitudes, which also coincide with the counterparts in $N = 4$ SYM. This generalizes the so-called maximal transcendentality principle to the Higgs amplitudes with external quark states, thus to the full QCD theory. We further verify that the correspondence applies also to two-loop form factors of more general operators, in both QCD and scalar-YM theory. Another interesting relation is also observed between the planar $H \to q q ˉ g$ amplitudes and the minimal density form factors in $N = 4$ SYM.
↳ hep-thhep-phCommun.Theor.Phys.(2020)·20 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.