HEP Phenomenology·hep-ph

Tue·May 14, 2019Tuesday·May 14, 2019

42 papers—30 primary·12 cross-listed·reconstructed*

01*
Longitudinal profiles of Extensive Air Showers with inclusion of charm and bottom particles
M. A. Muller🇧🇷 · Victor P. Gonçalves🇧🇷
Charm and bottom particles are rare in Extensive Air Showers but the effect of its presence can be radical in the development of the Extensive Air Showers (EAS). If such particles arise with a large fraction of the primary energy, they can reach large atmospheric depths, depositing its energy in deeper layers of the atmosphere. As a consequence, the EAS observables ( $X_{ma x}$ , $R M S$ and $N_{ma x}$ ) will be modified, as well as the shape of the longitudinal profile of the energy deposited in the atmosphere. In this paper, we will modify the CORSIKA Monte Carlo by the inclusion of charm and bottom production in the first interaction of the primary cosmic ray. Results for different selections of the typical $x_{F}$ values of the heavy particles and distinct production models will be presented.
hep-phInt.J.Mod.Phys.A(2019)·3 citations
02*
A solution for the doublet-triplet splitting in $S U (5)$
Renata Jora🇷🇴
We present a solution to the doublet-triplet splitting problem in supersymmetric $S U (5)$ by enlarging the group to $S U (5) \times S U (5)$ and by introducing two supermultiplets in the $(5, 5)$ and $(5 ˉ, 5 ˉ)$ representations of the extended group. The non-perturbative superpotential associated to this gauge group provides not only the correct gauge symmetry breaking but also the large mass for the Higgs triplets associated to massless Higgs doublet. The method has all the advantages of the sliding singlet model but without the drawbacks.
hep-phhep-th1 citation
03*
Hadron production in d-Au, p-Pb, Pb-Pb and Xe-Xe collisions at RHIC and LHC: onset of color glass condensate in light of an analytical solution of BK equation
P. Phukan🇮🇳 · M. Lalung🇮🇳 · J. K. Sarma🇮🇳
An exact analytical solution to the Balitsky-Kovchegov equation is proposed incorporating Mellin transformation with saddle point approximation. The theoretical significance of this solution is its simplicity in form which requires very less number of parameters. Using this solution along with the idea of color glass condensate, a very good description of RHIC and LHC data on differential yield is obtained for d-Au, p-p and p-Pb collisions. Quantitative prediction for the nuclear modification factors for p-Pb, Pb-Pb and Xe-Xe collisions relevant for very recent LHC run 2 is yielded.
hep-ph0 citations
04*
Two-loop evolution equation for the B-meson distribution amplitude
V. M. Braun🇩🇪 · Yao Ji🇩🇪 · A. N. Manashov🇩🇪
We derive the two-loop evolution equation of the B-meson light-cone distribution amplitude which is the last missing element for the next-to-next-to-leading logarithmic resummation of QCD corrections to B decays in QCD factorization. We argue that the evolution kernel to all orders in perturbation theory can be written as a logarithm of the generator of special conformal transformations times the cusp anomalous dimension, up to a scheme-dependent overall constant. Up to this constant term, the evolution kernel to a given order in perturbation theory can be obtained from the calculation of special conformal anomaly at one order less.
hep-phhep-thPRD(2019)·53 citations
05*
Symmetry Breaking and Proton Decay in Spectral Pati-Salam Model
Hosein Karimi Khozani🇱🇧
We show the scalar potential in the spectral Pati-Salam model does not provide a suitable vacuum to break to the standard model. We see this potential is proton decay free although diquark and leptoquark vertices exist.
hep-ph0 citations
06*
Dark Matter Bound States from Three-Body Recombination
Eric Braaten🇺🇸 · Daekyoung Kang🇨🇳 · Ranjan Laha🇩🇪
The small-scale structure problems of the universe can be solved by self-interacting dark matter that becomes strongly interacting at low energies. A particularly predictive model is resonant short-range self-interactions, with a dark-matter mass of about 19 GeV and a large S-wave scattering length of about 17 fm. Such a model makes definite predictions for the few-body physics of weakly bound clusters of the dark-matter particles. We calculate the production of two-body bound clusters by three-body recombination in the early universe under the assumption that the dark matter particles are identical bosons, which is the most favorable case for forming larger clusters. The fraction of dark matter in the form of two-body bound clusters can increase by as much as 4 orders of magnitude when the dark-matter temperature falls below the binding energy, but its present value remains less than 10^(-6).
hep-phSpringer Proc.Phys.(2020)·1 citation
07*
Mixed hidden sector/visible sector dark matter and observation of CP odd Higgs at HL-LHC and HE-LHC
Amin Aboubrahim🇺🇸 · Pran Nath🇺🇸
It is very likely that similar to the case of visible matter, dark matter too is composed of more than one stable component. In this work we investigate a two-component dark matter with one component from the visible sector and the other from the hidden sector. Specifically we consider a $U (1)_{X}$ hidden sector extension of MSSM/SUGRA where we allow for kinetic and Stueckelberg mass mixing between the two abelian $U (1)^{'} s$ , i.e., $U (1)_{X}$ and $U (1)_{Y}$ . We further assume that the hidden sector has chiral matter which leads to a Dirac fermion as a candidate for dark matter. The lightest neutralino in the visible sector and the Dirac fermion in the hidden sector then constitute the two components of dark matter. We investigate in particular MSSM/SUGRA models with radiative breaking occurring on the hyperbolic branch where the Higgs mixing parameter $μ$ is small (order the electroweak scale) which leads to a lightest neutralino being dominantly a higgsino. While dark matter constituted only of higgsinos is significantly constrained by data on dark matter relic density and by limits on spin independent proton-DM scattering cross section, consistency with data can be achieved if only a fraction of the dark matter relic density is constituted of higgsinos with the rest coming from the hidden sector. An aspect of the proposed model is the prediction of a relatively light CP odd Higgs $A$ (as well as a CP even $H$ and a charged Higgs $H^{\pm}$ ) which is observable at HL-LHC and HE-LHC. We perform a detailed collider analysis search for the CP odd Higgs using boosted decision trees in $τ_{h} τ_{h}$ final states and compare the discovery potential at HL-LHC and HE-LHC. We show that while several of the points among our benchmarks may be observable at HL-LHC, all of them are visible at HE-LHC with much lower integrated luminosities thus reducing significantly the run time for discovery.
hep-phhep-exPRD(2019)·12 citations
08*
A diquark model for the d*(2380) dibaryon resonance?
Avraham Gal🇮🇱 · Marek Karliner🇮🇱
Diquark models have been applied with varying degree of success to tetraquark and pentaquark states involving both light and heavy quark degrees of freedom. We discuss the applicability of such models to light quark dibaryons, viewed as three-diquark objects. Highlighting the case of the d*(2380) dibaryon resonance, we demonstrate the inapplicability of diquark models in the light quark sector.
hep-phnucl-exnucl-thEPJC(2019)·7 citations
09*
A Unique Multi-Messenger Signal of QCD Axion Dark Matter
Thomas D. P. Edwards🇳🇱 · Marco Chianese🇳🇱 · Bradley J. Kavanagh🇳🇱 · Samaya M. Nissanke🇳🇱 · Christoph Weniger🇳🇱
We propose a multi-messenger probe of QCD axion Dark Matter based on observations of black hole-neutron star binary inspirals. It is suggested that a dense Dark Matter spike may grow around intermediate mass black holes ( $1 0^{3} - 1 0^{5} M_{⊙}$ ). The presence of such a spike produces two unique effects: a distinct phase shift in the gravitational wave strain during the inspiral and an enhancement of the radio emission due to the resonant axion-photon conversion occurring in the neutron star magnetosphere throughout the inspiral and merger. Remarkably, the observation of the gravitational wave signal can be used to infer the Dark Matter density and, consequently, to predict the radio emission. We study the projected reach of the LISA interferometer and next-generation radio telescopes such as the Square Kilometre Array. Given a sufficiently nearby system, such observations will potentially allow for the detection of QCD axion Dark Matter in the mass range $1 0^{- 7} eV$ to $1 0^{- 5} eV$ .
hep-phastro-ph.COastro-ph.HEgr-qcPRL(2020)·73 citations
10*
Probing low-mass WIMP candidates of dark matter with tetrafluoroethane superheated liquid detectors
Susnata Seth🇮🇳 · Sunita Sahoo🇮🇳 · Pijushpani Bhattacharjee🇮🇳 · Mala Das🇮🇳
Probing low mass (sub-GeV -- few GeV) Weakly Interacting Massive Particle (WIMP) candidates of dark matter through WIMP-induced nuclear recoils in direct detection experiments requires use of detector materials consisting of low mass target nuclei and low threshold energy. Here we explore the potential of superheated liquid detectors (SLD) with a hydrogen containing liquid, namely, tetrafluoroethane (C $_{2}$ H $_{2}$ F $_{4}$ ) (b.p.~ $- 26. 3^{\circ}$ C), as the target material for probing low mass WIMPs. It is found that few-keV level recoil energy thresholds possible for bubble nucleation by WIMP-induced $^{12}$ C and $^{19}$ F recoils in C $_{2}$ H $_{2}$ F $_{4}$ SLDs operated at atmospheric pressure and gamma-ray insensitive temperatures of $T ≲ 3 5^{\circ}$ C have the potential to allow WIMPs in the few-GeV mass range to be probed at a WIMP-nucleon spin-independent cross section sensitivity levels (90% C.L.) better than $4.6 \times 1 0^{- 5}$ pb at WIMP masses down to $\sim$ 4 GeV with a total exposure of $\sim$ 1000 kg.day, provided that the ``thermodynamic efficiency" $η_{T}$ that determines the bubble nucleation thresholds for the recoiling nuclei in C $_{2}$ H $_{2}$ F $_{4}$ is $\sim$ 50% or higher. Sensitivity to sub-GeV WIMP masses generally requires the detector to be sensitive to the WIMP-induced $^{1}$ H recoils, which in turn requires the detector to be operated at temperatures $T ≳ 5 0^{\circ}$ C and $η_{T}$ close to 100%. At such relatively high temperatures (at atmospheric pressure), however, the detector would be sensitive to background gamma rays.
hep-phastro-ph.GAPRD(2020)·13 citations
11*
Higgs boson decay into four bottom quarks in the SM and beyond
Jun Gao🇨🇳
We present predictions for the Higgs boson decay into four bottom quarks in the standard model and via light exotic scalars retaining full bottom-quark mass dependence. In the SM the decay can be induced either by the Yukawa couplings of bottom quarks and top quarks or the electroweak couplings. We calculate the partial decay width and various differential distributions up to next-to-leading order in QCD. We find large QCD corrections for decay via Yukawa couplings, as large as 90% for the partial decay width, and reduced scale variations. The results of this paper are therefore helpful for the measurement of this multi-jets final state at future Higgs factory of electron-positron colliders. We also propose several observables that can differentiate the SM decay channel and the exotic decay channel and compare their next-to-leading order predictions.
hep-phJHEP(2019)·10 citations
12*
On reggeization of vertex of three reggeized gluons in high energy QCD
S.Bondarenko🇮🇱 · S.Pozdnyakov🇮🇱
The unitarity corrections to the propagator of reggeized gluons calculated in the framework of QCD RFT require a knowledge of the expressions for Reggeon propagator and vertices of interaction of three reggeized gluons (Reggeons) to one QCD loop precision, see \cite{Our6}. In this paper we calculate the vertex of interactions of $A_{+} A_{+} A_{-}$ Reggeon fields, i.e. vertex of transition of $A_{-}$ Reggeon field to $A_{+} A_{+}$ fields, to this precision. We demonstrate, that all loop leading logarithmic order contributions to the vertex can be summed through the integro-differential equation similarly to the BFKL one, \cite{BFKL}. The solution of this equation leads to the reggeized from of the vertex with the trajectory twice larger then the trajectory of reggeized gluon propagator. The application of the obtained result is also discussed.
hep-phhep-th4 citations
13*
Constraining the MSSM Higgs sector using precise Higgs mass predictions
Henning Bahl🇩🇪
Different approaches are used for the calculation of the SM-like Higgs boson mass in the MSSM: the fixed-order diagrammatic approach is accurate for low SUSY scales; the EFT approach,for high SUSY scales. Hybrid approaches, combining fixed-order and EFT calculations, allow to obtain a precise prediction also for intermediary SUSY scales. Here, we briefly discuss the hybrid approach implemented into the code FeynHiggs. In addition, we show how the refined Higgs mass prediction was used to define new MSSM Higgs benchmark scenarios.
hep-ph2 citations
14*
Dense QCD(-like) Matter in Strong Magnetic Fields
Helena Kolešová🇳🇴
As recently shown, the ground state of dense QCD matter in a strong magnetic field is an inhomogeneous condensate of neutral pions which was named Chiral Soliton Lattice (CSL) phase in analogy with a state present for chiral magnets. We continue this work by showing that similar phase is present for a class of QCD-like theories which are accessible to standard lattice Monte-Carlo simulations unlike the QCD itself which suffers from the notorious sign problem if non-zero baryon chemical potential is considered. On the occasion of the Gravitation session of the Moriond conference we also briefly comment on the possible relevance of the CSL phase for neutron stars and gravitational wave observations.
hep-ph0 citations
15*
$^{8}$ Be Decay Anomaly and Light $Z^{'}$
Luigi Delle Rose🇮🇹 · Shaaban Khalil🇪🇬 · Simon J.D. King🇬🇧 · Stefano Moretti🇬🇧 · Ahmed M. Thabt🇪🇬
In this proceedings, we discuss a light (17 MeV) $Z^{'}$ solution to the anomaly observed in the decay of Beryllium-8 by the Atomki collaboration. We detail an anomaly free model with minimal particle content which can satisfy all other experimental constraints with gauge couplings $O (1 0^{- 4})$ .
hep-ph4 citations
16*
Investigation of two photon emission in strong field QED using channeling in a crystal
Tobias N. Wistisen🇩🇪
We investigate the 2nd order process of two photons being emitted by a high-energy electron dressed in the strong background electric field found between the planes in a crystal. The strong crystalline field combined with ultra relativistic electrons is one of very few cases where the Schwinger field can be experimentally achieved in the electron's rest frame. The radiation being emitted, the so-called channeling radiation, is a well studied phenomenon. However only the first order diagram corresponding to emission of a single photon has been studied so far. We elaborate on how the 2 photon emission process should be understood in terms of a two-step versus a one-step process, i.e., if one can consider one photon being emitted after the other, or if there is also a contribution where the two photons are emitted 'simultaneously'. From the calculated full probability we see that the two-step contribution is simply the product of probabilities for single photon emission while the additional one-step terms are, mainly, interferences due to several possible intermediate virtual states. These terms can contribute significantly when the crystal is thin. Therefore, in addition, we see how one can, for a thick crystal, calculate multiple photon emissions quickly by neglecting the one-step terms, which represents a solution of the problem of quantum radiation reaction in a crystal beyond the usually applied constant field approximation. We explicitly calculate an example of 180 GeV electrons in a thin Silicon crystal and argue why it is, for experimental reasons, more feasible to see the one-step contribution in a crystal experiment than in a laser experiment.
hep-phPRD(2019)·6 citations
17*
Pion and Kaon form factors in the perturbative QCD approach
Shan Cheng🇨🇳
We present the most accurate calculation for the pion and kaon electromagnetic form factors in the framework of perturbative QCD, where the power corrections up to twist-4 of the meson distribution amplitudes and the next-to-leading-order QCD corrections up to subleading power are included. In order to guarantee the gauge invariance of the meson to vacuum matrix element, we take into account both assignments with the lowest Fock state and the high Fock state with an additional valence gluon. Our results confirm the power behaviour of the twist expansion and show the chiral enhancement effect at subleading power in the PQCD approach. We also estimate the $SU (3)$ asymmetry for the kaon and pion form factors and find that it is smaller than $30%$ .
hep-phPRD(2019)·13 citations
18*
Theory for the FCC-ee : Report on the 11th FCC-ee Workshop
A. Blondel🇨🇭 · J. Gluza🇵🇱 · S. Jadach🇵🇱 · P. Janot🇨🇭 · T. Riemann🇵🇱 · S. Abreu🇧🇪 · J.J. Aguilera-Verdugo🇪🇸 · A.B. Arbuzov🇷🇺 · J. Baglio🇩🇪 · S.D. Bakshi🇮🇳 · S. Banerjee🇺🇸 · M. Beneke🇩🇪 and 74 other authors
The Future Circular Collider (FCC) at CERN, a proposed 100-km circular facility with several colliders in succession, culminates with a 100 TeV proton-proton collider. It offers a vast new domain of exploration in particle physics, with orders of magnitude advances in terms of Precision, Sensitivity and Energy. The implementation plan foresees, as a first step, an Electroweak Factory electron-positron collider. This high luminosity facility, operating between 90 and 365 GeV centre-of-mass energy, will study the heavy particles of the Standard Model, Z, W, Higgs, and top with unprecedented accuracy. The Electroweak Factory $e^{+} e^{-}$ collider constitutes a real challenge to the theory and to precision calculations, triggering the need for the development of new mathematical methods and software tools. A first workshop in 2018 had focused on the first FCC-ee stage, the Tera-Z, and confronted the theoretical status of precision Standard Model calculations on the Z-boson resonance to the experimental demands. The second workshop in January 2019, which is reported here, extended the scope to the next stages, with the production of W-bosons (FCC-ee-W), the Higgs boson (FCC-ee-H) and top quarks (FCC-ee-tt). In particular, the theoretical precision in the determination of the crucial input parameters, alpha_QED, alpha_QCD, M_W, m_t at the level of FCC-ee requirements is thoroughly discussed. The requirements on Standard Model theory calculations were spelled out, so as to meet the demanding accuracy of the FCC-ee experimental potential. The discussion of innovative methods and tools for multi-loop calculations was deepened. Furthermore, phenomenological analyses beyond the Standard Model were discussed, in particular the effective theory approaches. The reports of 2018 and 2019 serve as white papers of the workshop results and subsequent developments.
hep-phhep-exCERN Yellow Reports: Monographs, CERN-202…·79 citations
19*
Revisiting the form factors of $P \to V$ transition within the light-front quark models
Qin Chang🇨🇳 · Xiao-Nan Li🇨🇳 · Li-Ting Wang🇨🇳
We investigate the self-consistency and Lorentz covariance of the covariant light-front quark model~(CLF QM) via the matrix elements and form factors~( $F = g$ , $a_{\pm}$ and $f$ ) of $P \to V$ transition. Two types of correspondence schemes between the manifest covariant Bethe-Salpeter approach and the light-front quark model are studied. We find that, for $a_{-} (q^{2})$ and $f (q^{2})$ , the CLF results obtained via $\lbd = 0$ and $\pm$ polarization states of vector meson within the traditional type-I correspondence scheme are inconsistent with each other; and moreover, the strict covariance of the matrix element is violated due to the nonvanishing spurious contributions associated with noncovariance. We further show that such two problems have the same origin and can be resolved simultaneously by employing the type-II correspondence scheme, which advocates an additional replacement $M \to M_{0}$ relative to the traditional type-I scheme; meanwhile, the results of $F (q^{2})$ in the standard light-front quark model~(SLF QM) are exactly the same as the valence contributions and equal to numerally the full results in the CLF QM, {\it i.e.}, $[F]_{SLF} = [F]_{val.} ≐ [F]_{full}$ . The numerical results for some $P \to V$ transitions are updated within the type-II scheme. Above findings confirm the conclusion obtained via the decay constants of vector and axial-vector mesons in the previous works.
hep-phEPJC(2019)·42 citations
20*
Simulation of vector boson plus many jet final states at the high luminosity LHC
Stefan Höche🇺🇸 · Stefan Prestel🇸🇪 · Holger Schulz🇺🇸
We present a novel event generation framework for the efficient simulation of vector boson plus multi-jet backgrounds at the high-luminosity LHC and at possible future hadron colliders. MPI parallelization of parton-level and particle-level event generation and storage of parton-level event information using the HDF5 data format allow us to obtain leading-order merged Monte-Carlo predictions with up to nine jets in the final state. The parton-level event samples generated in this manner correspond to an integrated luminosity of 3ab-1 and are made publicly available for future phenomenological studies.
hep-phhep-exPRD(2019)·66 citations
21*
Flow in AA and pA as an interplay of fluid-like and non-fluid like excitations
Aleksi Kurkela🇨🇭 · Urs Achim Wiedemann🇨🇭 · Bin Wu🇨🇭
To study the microscopic structure of quark-gluon plasma, data from hadronic collisions must be confronted with models that go beyond fluid dynamics. Here, we study a simple kinetic theory model that encompasses fluid dynamics but contains also particle-like excitations in a boost invariant setting with no symmetries in the transverse plane and with large initial momentum asymmetries. We determine the relative weight of fluid dynamical and particle like excitations as a function of system size and energy density by comparing kinetic transport to results from the 0th, 1st and 2nd order gradient expansion of viscous fluid dynamics. We then confront this kinetic theory with data on azimuthal flow coefficients over a wide centrality range in PbPb collisions at the LHC, in AuAu collisions at RHIC, and in pPb collisions at the LHC. Evidence is presented that non-hydrodynamic excitations make the dominant contribution to collective flow signals in pPb collisions at the LHC and contribute significantly to flow in peripheral nucleus-nucleus collisions, while fluid-like excitations dominate collectivity in central nucleus-nucleus collisions at collider energies.
hep-phhep-exnucl-exnucl-thEPJC(2019)·112 citations
22*
Thermal radiation and inclusive production in the KLN model for ion-ion collisions
E. Gotsman (Tel Aviv U.)🇮🇱 · E. Levin (Tel Aviv U./UTFSM)🇮🇱
We show that in order to obtain a successful description of the transverse momenta distribution for charged particles in ion-ion collisions, one must include a thermal emission term. The temperature of this emission $T_{th}$ turns out to be proportional to the saturation scale, $T_{th} = 1.8/2 π Q_{s}$ . The formalism for the calculation of the transverse momenta spectra in CGC/saturation approach is developed, in which two stages of the process are seen: creation of the colour glass condensate, and hadronization of the gluon jets. Our calculations are based on the observation that even for small values of $p_{T}$ , the main contribution in the integration over the dipole sizes stems from the kinematic region in vicinity of the saturation momentum, where theoretically, we know the scattering amplitude. Non-perturbativ corrections need to be included in the model of hadronization. This model incorporates the decay of a gluon jet with effective mass $m_{eff}^{2} = 2 Q_{s} μ_{soft}$ where $μ_{soft}$ denotes the soft scale, with the fragmentation functions at all values of the transverse momenta. We use the KLN model which, provides a simple way to estimate the cross sections for the different centrality classes. Comparing the results of this paper with the transverse distribution in the proton-proton scattering, we see two major differences. First, a larger contribution of the thermal radiation term is needed, in accord with higher parton densities of the produced colour glass condensate. Second, even changing the model for the hadronization, without a thermal radiation term, we fail to describe the $p_{T}$ spectrum. Consequently, we conjecture that theexistence of the thermal radiation term is independent of the model of confinement.
hep-phnucl-thPRD(2019)·12 citations
23*
The transverse momentum spectrum of weak gauge bosons at N $^{3}$ LL+NNLO
Wojciech Bizon🇩🇪 · Aude Gehrmann-De Ridder🇨🇭 · Thomas Gehrmann🇨🇭 · Nigel Glover🇬🇧 · Alexander Huss🇨🇭 · Pier Francesco Monni🇨🇭 · Emanuele Re🇨🇭 · Luca Rottoli🇮🇹 · Duncan M. Walker🇬🇧
We present accurate QCD predictions for the transverse momentum pT spectrum of electroweak gauge bosons at the LHC for 13 TeV collisions, based on a consistent combination of a NNLO calculation at large pT and N3LL resummation in the small pT limit. The inclusion of higher order corrections leads to substantial changes in the shape of the differential distributions, and the residual perturbative uncertainties are reduced to the few percent level across the whole transverse momentum spectrum. We examine the ratio of pT distributions in charged- and neutral-current Drell-Yan production, and study different prescriptions for the estimate of perturbative uncertainties that rely on different degrees of correlation between these processes. We observe an excellent stability of the ratios with respect to the perturbative order, indicating a strong correlation between the corresponding QCD corrections.
hep-phhep-exEPJC(2019)·113 citations
24*
Light-Quark Dipole Operators at LHC
Eduardo da Silva Almeida🇧🇷 · N. Rosa Agostinho🇪🇸 · Oscar J. P. Éboli🇧🇷 · M. C. Gonzalez-Garcia🇪🇸
We study the effect of operators generating dipole couplings of the light quarks to electroweak gauge bosons on several observables at LHC. We start by demonstrating that the determination of the gauge boson self-couplings from electroweak diboson production at LHC is robust under the inclusion of those quark dipole operators even when let them totally unconstrained in the analysis. Conversely, we determine the bounds that the diboson data imposes on the light-quark dipole couplings and show that they represent a significant improvement over the limits arising from Z and W electroweak precision measurements. We also explore the sensitivity of the Drell-Yan cross section determination at LHC Run 1, and the results on resonance searches in high invariant-mass lepton pair production at Run 2 to further constrain the electroweak dipole couplings of the light quarks.
hep-phPRD(2019)·21 citations
25*
Direct Detection Anomalies in light of $G aia$ Data
Matthew R. Buckley🇺🇸 · Gopolang Mohlabeng🇺🇸 · Christopher W. Murphy🇺🇸
Measurements from the Gaia satellite have greatly increased our knowledge of the dark matter velocity distributions in the Solar neighborhood. There is evidence for multiple cold structures nearby, including a high-velocity stream counterrotating relative to the Sun. This stream could significantly alter the spectrum of recoil energies and increase the annual modulation of dark matter in direct detection experiments such as DAMA/Libra. We reanalyze the experimental limits from Xenon1T, CDMSlite, PICO-60 and COSINE-100, and compare them to the results of the DAMA/Libra experiment. While we find that this new component of the dark matter velocity distribution can greatly improve the fit to the DAMA/Libra data, both spin-independent and spin-dependent interpretations of the DAMA/Libra signal with elastic and inelastic scattering continue to be ruled out by the null results of other experiments, in particular Xenon1T.
hep-phastro-ph.COPRD(2019)·13 citations
26*
The Inflaton Portal to a Highly decoupled EeV Dark Matter Particle
Lucien Heurtier🇺🇸 · Fei Huang🇺🇸
We explore the possibility that the dark-matter relic abundance is generated in a context where the inflaton is the only mediator between the visible and the hidden sectors of our universe. Due to the relatively large mass of the inflaton field, such a portal leads to an extremely feeble interaction between the dark and the visible sectors suggesting that the dark sector cannot reach any thermal equilibrium with the visible sector. After the two sectors are populated by the decay of the inflaton, a heavy dark-matter particle thermally decouples within the dark sector. Later, a lighter dark particle, whose decay width is naturally suppressed by the inflaton propagator, decays into the visible sector after it dominates the energy density of universe. This process dilutes the dark-matter relic density by injecting entropy in the visible sector. We show that an inflaton mass of $O (1 0^{13})$ GeV together with couplings of order one are fully compatible with a dark-matter relic abundance $Ω h^{2} \sim 0.1$ . As a general feature of the model, the entropy dilution mechanism is accompanied by a period of early matter domination, which modifies the amount of e-folds of inflation necessary to accommodate Planck data. Moreover, the coupling of the inflaton to the dark and visible sectors brings loop contributions to the inflationary potential which can destabilize the inflation trajectory. Considering all these complementary constraints, we show that, in the context of a plateau-inflation scenario such as the $α$ -attractor model, the inflaton can constitute a viable mediator between the visible sector and a $\sim 10$ EeV dark-matter candidate. Furthermore, we show that improved constraints on the tensor-to-scalar ratio and spectral index could potentially rule out dark-matter scenarios of this sort in the future.
hep-phastro-ph.COastro-ph.HEPRD(2019)·42 citations
27*
Axion-like-particle decay in strong electromagnetic backgrounds
B. King🇬🇧 · B. M. Dillon🇸🇮 · K. A. Beyer🇬🇧 · G. Gregori🇬🇧
The decay of a massive pseudoscalar, scalar and U(1) boson into an electron-positron pair in the presence of strong electromagnetic backgrounds is calculated. Of particular interest is the constant-crossed-field limit, relevant for experiments that aim to measure high-energy axion-like-particle conversion into electron-positron pairs in a magnetic field. The total probability depends on the quantum nonlinearity parameter - a product of field and lightfront momentum invariants. Depending on the seed particle mass, different decay regimes are identified. In the below-threshold case, we find the probability depends on a non-perturbative tunnelling exponent depending on the quantum parameter and the particle mass. In the above-threshold case, we find that when the quantum parameter is varied linearly, the probability oscillates nonlinearly around the spontaneous decay probability. A strong-field limit is identified in which the threshold is found to disappear. In modelling the fall-off of a quasi-constant-crossed magnetic field, we calculate probabilities beyond the constant limit and investigate when the decay probability can be regarded as locally constant.
hep-phJHEP(2020)·21 citations
28*
On the Determination of Leptonic CP Violation and Neutrino Mass Ordering in Presence of Non-Standard Interactions: Present Status
Ivan Esteban🇪🇸 · M.C. Gonzalez-Garcia🇪🇸 · Michele Maltoni🇪🇸
We perform a global analysis of neutrino data in the framework of three massive neutrinos with non-standard neutrino interactions which affect their evolution in the matter background. We focus on the effect of NSI in the present observables sensitive to leptonic CP violation and to the mass ordering. We consider complex neutral current neutrino interactions with quarks whose lepton-flavor structure is independent of the quark type. We quantify the status of the "hints" for CP violation, the mass-ordering and non-maximality of $θ_{23}$ in these scenarios. We also present a parametrization-invariant formalism for leptonic CP violation in presence of a generalized matter potential induced by NSI.
hep-phhep-exJHEP(2019)·65 citations
29*
Pati-Salam and lepton universality in B decays
Julian Heeck🇺🇸 · Daniele Teresi🇮🇹
Recent hints for lepton-flavor non-universality in $B$ -meson decays can be interpreted as hints for the existence of leptoquarks. We show that scalar leptoquarks unavoidably arise in grand unified theories, using the well-known Pati-Salam model as an example. These GUT-motivated leptoquarks can have a number of appealing features including automatic absence of proton decay, purely chiral couplings, and relations between the various leptoquark couplings. We show that $R (K^{(*)})$ can be connected to the neutrino mass matrix that arises via type-II seesaw, resulting in testable lepton flavor violation. In order to also explain $R (D^{(*)})$ one instead has to assume the existence of light right-handed neutrinos, once again with testable predictions in other $B$ -meson decays and at the LHC.
hep-phhep-ex2 citations
30*
Implications of detecting the Axion-Like Particles in Astro-Particle Physics
K K Singh🇮🇳
Axions and axion like particles in general are consequences of the extensions of the standard model in particle physics. Axions have been proposed as hypothetical pseudo-scalar particles in particle physics to solve the strong Charge-Parity problem using quantum chromodynamics. These particles are also proposed to be an attractive candidate for cold dark matter in the Universe. The current understanding of the existence and properties of the axions is not very clear and these hypothetical particles remain elusive. However many theoretical and experimental searches are being made for understanding and constraining the properties of axions via detection of axion like particles. The term axion like particles is used to include different types of axions going beyond the standard model. In this paper, we review the different physical properties of axions and axion like particles and their possible sources in the laboratory and Universe. We discuss different experimental set ups for detection of axion like particles proposed in the literature. Implications of detecting the axion like particles in the areas of particle physics, astrophysics and cosmology are also discussed in the framework of present and future motivations.
hep-phastro-ph.HEVolume 3, Issue 1, February 2019·0 citations
31*
Type II critical behavior of gravitating magnetic monopoles
Ben Kain🇺🇸
I study type II critical collapse in the spherically symmetric gravitating magnetic monopole system. This is an Einstein-Yang-Mills-Higgs system with two matter fields: a field parametrizing the scalar field gauged under SU(2) and a field parametrizing the gauge field. This system offers interesting differences compared to what is commonly found for type II collapse in other systems. For example, instead of the critical solution sitting between collapse and complete dispersal of the matter fields, on the non-black hole side of the critical solution, the matter fields settle down to a static and stable configuration. More interesting, however, is that I find strong evidence for the existence of two critical solutions, each with their own set of scaling and echoing exponents, which I determine numerically.
↳ gr-qchep-phhep-thPRD(2019)·7 citations
32*
Eigenvalues and eigenstates of the many-body collective neutrino oscillation problem
Amol V. Patwardhan🇺🇸 · Michael J. Cervia🇺🇸 · A. Baha Balantekin🇺🇸
We demonstrate a method to systematically obtain eigenvalues and eigenstates of a many-body Hamiltonian describing collective neutrino oscillations. The method is derived from the Richardson-Gaudin framework, which involves casting the eigenproblem as a set of coupled nonlinear "Bethe Ansatz equations", the solutions of which can then be used to parametrize the eigenvalues and eigenvectors. The specific approach outlined in this paper consists of defining auxiliary variables that are related to the Bethe-Ansatz parameters, thereby transforming the Bethe-Ansatz equations into a different set of equations that are numerically better behaved and more tractable. We show that it is possible to express not only the eigenvalues, but also the eigenstates, directly in terms of these auxiliary variables without involving the Bethe Ansatz parameters themselves. In this paper, we limit ourselves to a two-flavor, single-angle neutrino system.
↳ nucl-thastro-ph.HEhep-phquant-phPRD(2019)·46 citations
33*
Dimensional reduction of the electromagnetic sector of the nonminimal Standard-Model-Extension
Manoel M. Ferreira Jr.🇧🇷 · João A.A.S. Reis🇧🇷 · Marco Schreck🇧🇷
In the current paper, we construct a Lorentz-violating electrodynamics in (1+2) spacetime dimensions from the electromagnetic sector of the nonminimal Standard-Model Extension (SME) in (1+3) dimensions. Subsequently, we study some of the basic properties of this framework. We obtain the field equations, the Green's functions, and the perturbative Feynman rules. Furthermore, the modified dispersion relations are computed at leading order in Lorentz violation. We then remove the unphysical degrees of freedom from the electromagnetic Green's function that are present due to gauge invariance. The resulting object is used to construct the general solutions of the uncoupled field equations with external inhomogeneities present. This modified planar electrodynamics may be valuable to describe electromagnetic phenomena in two-dimensional condensed-matter systems. Furthermore, it supports a better understanding of the electromagnetic sector of the nonminimal SME.
↳ hep-thhep-phPRD(2019)·18 citations
34*
Electron-positron pair production in an oscillating Sauter potential
Li Wang🇨🇳 · Binbing Wu🇨🇳 · Baisong Xie🇨🇳
Electron-positron pair production in an oscillating Sauter potential is investigated in the framework of the computational quantum field theory. It is found that for a Sauter potential well with oscillating width and depth simultaneously, the phase difference between them has a great impact on the number of created electron-positron pairs. Optimal values of the phase difference corresponding to different oscillation frequencies are obtained. The optimal phase difference has a strong nonlinear dependence on oscillating frequency. When the potential well changes slowly, our results can be explained by the instantaneous bound states. For the higher frequency case, however, multiphoton effect is enhanced and the Pauli blocking effect has a strong inhibitory effect on pair creations. These results can provide a theoretical reference for the experimental creation of the electron-positron pairs.
↳ quant-phhep-phPRA(2019)·20 citations
35*
No hair theorem for bound-state massless static scalar fields outside horizonless Neumann compact stars
Yan Peng🇨🇳
We study no-hair theorem for horizonless objects, being subject to Neumann boundary conditions. For massive scalar fields, a no hair theorem for Neumann compact stars was proved by us in a previous paper, where the nonzero scalar field mass condition is essential in the proof. In the present work, for massless scalar fields, we prove a no hair theorem, which claims that bound-state massless static scalar fields cannot exist outside asymptotically flat horizonless neutral Neumann compact stars.
↳ gr-qchep-phhep-thPLB(2019)·4 citations
36*
Do we Come from a Quantum Anomaly?
Spyros Basilakos🇬🇷 · Nick E. Mavromatos🇬🇧 · Joan Sola🇪🇸
We present a string-based picture of the cosmological evolution in which (CP-violating) gravitational anomalies acting during the inflationary phase of the universe cause the vacuum energy density to "run" with the effective Hubble parameter squared, $H^{2}$ , thanks to the axion field of the bosonic string multiplet. This leads to baryogenesis through leptogenesis with massive right-handed neutrinos. The generation of chiral matter after inflation helps in cancelling the anomalies in the observable radiation- and matter- dominated eras. The present era inherits the same "running vacuum" structure triggered during the inflationary time by the axion field. The current dark energy is thus predicted to be mildly dynamical, and dark matter should be made of axions. Paraphrasing Carl Sagan: "we are all anomalously made from starstuff " .
↳ hep-thastro-ph.COgr-qchep-phInt.J.Mod.Phys.D(2019)·34 citations
37*
Realising Mutated Hilltop Inflation in Supergravity
Tony Pinhero🇮🇳 · Supratik Pal🇮🇳
We present $N = 1$ supergravity models of mutated hilltop inflation (MHI) for both large and small field sectors. Models with canonical kinetic terms are developed based on a shift symmetric Kähler potential in inflaton superfield, and with a superpotential linear in Goldstino superfield. We also construct models with non-canonical kinetic terms for MHI by generalizing the shift symmetry. We found that a good fraction of the models can address the entire branch of MHI in a single framework.
↳ hep-thastro-ph.COhep-phPLB(2019)·7 citations
38*
Spectral and optical properties of Ag $_{3}$ Au(Se $_{2}$ ,Te $_{2}$ ) and dark matter detection
Miguel-Ángel Sánchez-Martínez🇫🇷 · Iñigo Robredo🇪🇸 · Arkaitz Bidauzarraga🇪🇸 · Aitor Bergara🇪🇸 · Fernando de Juan🇪🇸 · Adolfo G. Grushin🇫🇷 · Maia G. Vergniory🇪🇸
In this work we study the electronic structure of Ag $_{3}$ AuSe $_{2}$ and Ag $_{3}$ AuTe $_{2}$ , two chiral insulators whose gap can be tuned through small changes in the lattice parameter by applying hydrostatic pressure or choosing different growth protocols. Based on first principles calculations we compute their band structure for different values of the lattice parameters and show that while Ag $_{3}$ AuSe $_{2}$ retains its direct narrow gap at the $Γ$ point, Ag $_{3}$ AuTe $_{2}$ can turn into a metal. Focusing on Ag $_{3}$ AuSe $_{2}$ we derive a low energy model around $Γ$ using group theory, which we use to calculate the optical conductivity for different values of the lattice constant. We discuss our results in the context of detection of light dark matter particles, which have masses of the order of a $k$ eV, and conclude that Ag $_{3}$ AuSe $_{2}$ satisfies three important requirements for a suitable detector: small Fermi velocities, $m$ eV band gap and low photon screening. Our work motivates the growth of high-quality and large samples of Ag $_{3}$ AuSe $_{2}$ to be used as target materials in dark matter detectors.
↳ cond-mat.mtrl-scihep-phMaterials(2019)·14 citations
39*
Constant roll warm inflation in high dissipative regime
Vahid Kamali🇨🇦 · Michał Artymowski🇮🇱 · Mohammad Reza Setare🇮🇷
Constant-roll warm inflation is introduced in this work. A novel approach to finding an exact solution for Friedman equations coupled to scalar field equation of motion is presented for cold inflation and is extended to warm inflation with the constant dissipative parameter $Q = \frac{Γ}{3 H}$ . The evolution of the primordial inhomogeneities of a scalar field in a thermal bath is also studied. The $1 σ$ consistency between the theoretical predictions of the model and observational constraints has been proven for a range of $Q$ and $β = \frac{ϕ ¨}{3 H ϕ}$ (constant rate of inflaton roll). In addition, we briefly investigate the possible enhancement of super-horizon perturbations beyond the slow-roll approximation.
↳ gr-qchep-phhep-thJCAP(2020)·21 citations
40*
Spin polarization independence of hard polarized fermion string scattering amplitudes
Sheng-Hong Lai🇹🇼 · Jen-Chi Lee🇹🇼 · Yi Yang🇹🇼
We calculate a class of polarized fermion string scattering amplitudes (PFSSA) at arbitrary mass levels. We discover that, in the hard scattering limit, the functional forms of the non-vanishing PFSSA at each fixed mass level are independent of the choices of spin polarizations. This result justifies and extends Gross conjecture on high energy string scattering amplitudes to the fermionic sector. In addition, this peculiar property of hard PFSSA is to be compared with the usual spin polarization dependence of the hard polarized fermion field theory scatterings.
↳ hep-thhep-phPLB(2019)·7 citations
41*
Off-Shell Yang-Mills Amplitude in the CHY Formalism
C.S. Lam🇨🇦
Möbius invariance is used to construct gluon tree amplitudes in the Cachazo, He, and Yuan (CHY) formalism. If it is equally effective in steering the construction of off-shell tree amplitudes, then the S-matrix CHY theory can be used to replace the Lagrangian Yang-Mills theory. In the process of investigating this possibility, we find that the CHY formula can indeed be modified to obtain a Möbius invariant off-shell amplitude, but unfortunately this modified amplitude $M_{P}$ is not the Yang-Mills amplitude because it lacks gauge invariance. A complementary amplitude $M_{Q}$ must be added to restore gauge invariance, but its construction relies on the Lagrangian and not Möbius invariance. Although neither $M_{P}$ nor $M_{Q}$ is fully gauge invariant, both are partially gauge invariant in a sense to be explained. This partial gauge invariance turns out to be very useful for checking calculations. A Feynman amplitude so split into the sum of $M_{P}$ and $M_{Q}$ also contains fewer terms.
↳ hep-thhep-phPRD(2019)·7 citations
42*
Symmetry, symmetry breaking, and pion parton distributions
Minghui Ding🇨🇳 · Khepani Raya🇲🇽 · Daniele Binosi🇮🇹 · Lei Chang🇨🇳 · C. D. Roberts🇺🇸 · S. M. Schmidt🇩🇪
Pion valence, glue and sea distributions are calculated using a continuum approach to the two valence-body bound-state problem. Since the framework is symmetry preserving, physical features of the distributions are properly expressed. The analysis reveals that the emergent phenomenon of dynamical chiral symmetry breaking causes a hardening of the valence-quark distribution function, $q^{π} (x)$ . Nevertheless, this distribution exhibits the $x ≃ 1$ behaviour predicted by quantum chromodynamics (QCD). At the scale $ζ_{2} := 2$ GeV, the following momentum fractions are predicted: $⟨ x_{valence} ⟩ = 0.48 (3)$ , $⟨ x_{glue} ⟩ = 0.41 (2)$ , $⟨ x_{sea} ⟩ = 0.11 (2)$ . Evolving to $ζ = 5.2$ GeV, the result for $q^{π} (x)$ agrees with that computed using lattice QCD. These outcomes should both spur improved analyses of existing experiments and stimulate efforts to obtain new data on the pion distribution functions using available and envisioned facilities.
↳ nucl-thhep-exhep-lathep-ph+1PRD(2020)·129 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.