HEP Phenomenology·hep-ph

Fri·Dec 1, 2017Friday·December 1, 2017

44 papers—29 primary·15 cross-listed·reconstructed*

01*
Constraints on box-shaped cosmic ray electron feature from dark matter annihilation with the AMS-02 and DAMPE data
Lei Zu🇨🇳 · Cun Zhang🇨🇳 · Lei Feng🇨🇳 · Qiang Yuan🇨🇳 · Yi-Zhong Fan🇨🇳
Precise measurements of spectra of cosmic ray electrons and positrons can effectively probe the nature of dark matter (DM) particles. In a class of models where DM particles initially annihilate into a pair of intermediate particles which then decay into standard model particles, box-shaped spectra can be generated. Such a kind of spectra are distinct from astrophysical backgrounds, and can probably be regarded as characteristic features of the DM annihilation. In this work, we search for such a feature in the total electron plus positron spectrum measured by AMS-02 and DAMPE. No significant evidence for such a DM annihilation component has been found. The 95\% confidence level upper limits of the velocity-weighted annihilation cross section are derived, which range from $\sim 1 0^{- 26} c m^{3} s^{- 1}$ for DM mass of 50 GeV to $\sim 1 0^{- 23} c m^{3} s^{- 1}$ for DM mass of 10 TeV.
hep-phPRD(2018)·45 citations
02*
Lepton-portal Dark Matter in Hidden Valley model and the DAMPE recent results
Yi-Lei Tang🇰🇷 · Lei Wu🇨🇳 · Mengchao Zhang🇰🇷 · Rui Zheng🇺🇸
We study the recent $e^{\pm}$ cosmic ray excess reported by DAMPE in a Hidden Valley Model with lepton-portal dark matter. We find the electron-portal can account for the excess well and satisfy the DM relic density and direct detection bounds, while electron+muon/electron+muon+tau-portal suffers from strong constraints from lepton flavor violating observables, such as $μ \to 3 e$ . We also discuss possible collider signatures of our model, both at the LHC and a future 100 TeV hadron collider.
hep-phSCPMA(2018)·36 citations
03*
Spotlighting the sensitivities of T2HK,T2HKK and DUNE
Kaustav Chakraborty🇮🇳 · K. N. Deepthi🇮🇳 · Srubabati Goswami🇮🇳
Neutrino oscillation physics has entered the precision era and the potential forthcoming experiments Hyper-Kamiokande and Deep Under-ground Neutrino Experiment (DUNE) are expected to lead this endeavor. In this paper we perform a comprehensive study of the octant, mass hierarchy and CP discovery sensitivities of DUNE, T2HK & T2HKK in their individual capacity and investigate the synergies of the aforementioned experiments with the on going T2K and NO $ν$ A experiments. We present a comparative account of the probabilities at the three baselines and explore in detail the physics issues which can cause the discrepancies in the sensitivities among the different experiments. We also find out the optimal exposure required by these experiments for achieving $5 σ$ hierarchy and octant sensitivity and to discover CP violation at $3 σ$ for 60\% values of $δ_{C P}$ . In addition we vary the neutrino-antineutrino runtime ratios for T2HK & T2HKK and check if the sensitivities are affected significantly due to this.
hep-phNPB(2018)·24 citations
04*
Three-loop mixed QCD-electroweak corrections to Higgs boson gluon fusion
Marco Bonetti🇩🇪 · Kirill Melnikov🇩🇪 · Lorenzo Tancredi🇨🇭
We compute the contribution of three-loop mixed QCD-electroweak corrections ( $α_{S}^{2} α^{2}$ ) to the $g g \to H$ scattering amplitude. We employ the method of differential equations to compute the relevant integrals and express them in terms of Goncharov polylogarithms.
hep-phPRD(2018)·40 citations
05*
Prompt photon yield and $v_{2}$ coefficient from gluon fusion induced by magnetic field in heavy-ion collision
Jorge David Castaño-Yepes🇲🇽 · Alejandro Ayala🇲🇽 · C. A. Dominguez🇿🇦 · L. A. Hernández🇲🇽 · Saúl Hernández-Ortíz🇲🇽 · María Elena Tejeda-Yeomans🇲🇽
We compute the production of prompt photons and the $v_{2}$ harmonic coefficient in relativistic heavy-ion collisions induced by gluon fusion in the presence of an intense magnetic field, during the early stages of the reaction. The calculations take into account several parameters which are relevant to the description of the experimental transverse momentum distribution, and elliptic flow for RHIC and LHC energies. The main imput is the strength of the magnetic field which varies in magnitude from 1 to 3 times the pion mass squared, and allows the gluon fusion that otherwise is forbidden in the absence of the field. The high gluon occupation number and the value of the saturation scale also play an important role in our calculation, as well as a flow velocity and geometrical factors. Our results support the idea that the origin of at least some of the photon excess observed in heavy-ion experiments may arise from magnetic field induced processes, and gives a good description of the experimental data.
hep-phnucl-thEPJ Web Conf.(2018)·0 citations
06*
Vacuum Cherenkov radiation for Lorentz-violating fermions
M. Schreck🇧🇷
The current paper summarizes the content of a talk given on vacuum Cherenkov radiation emitted by Lorentz-violating fermions that are described in the context of the Standard-Model Extension. The decay rate will be obtained for various sets of controlling coefficients that will subsequently be constrained using cosmic-ray data.
hep-phJ.Phys.Conf.Ser.(2018)·6 citations
07*
The electron-flavored Z'-portal dark matter and the DAMPE cosmic ray excess
Wei Chao🇨🇳 · Qiang Yuan🇨🇳
The DAMPE experiment has recently reported strong indications for the existence of an excess of high-energy electrons and positrons. If interpreted in terms of the annihilation of dark matter, the DAMPE result restricts the dark matter mass and possible annihilation channels to a few case. In this paper we explain the DAMPE result with the electron-flavored $Z^{'}$ -portal fermionic dark matter. We show that the Dirac dark matter scenario is promising to explain the excess via the process $χ ˉ χ \to Z^{'} \to e ˉ e$ . The reduced annihilation cross section is limited in a range of $1 0^{- 26} \sim 1 0^{- 24} c m^{3} s^{- 1}$ to interpret the excess.
hep-ph34 citations
08*
Strange matter in compact stars
Thomas Klaehn🇺🇸 · David Blaschke🇷🇺
We discuss possible scenarios for the existence of strange matter in compact stars. The appearance of hyperons leads to a hyperon puzzle in ab-initio approaches based on effective baryon-baryon potentials but is not a severe problem in relativistic mean field models. In general, the puzzle can be resolved in a natural way if hadronic matter gets stiffened at supersaturation densities, an effect based on the quark Pauli quenching between hadrons. We explain the conflict between the necessity to implement dynamical chiral symmetry breaking into a model description and the conditions for the appearance of absolutely stable strange quark matter that require both, approximately masslessness of quarks and a mechanism of confinement. The role of strangeness in compact stars (hadronic or quark matter realizations) remains unsettled. It is not excluded that strangeness plays no role in compact stars at all. To answer the question whether the case of absolutely stable strange quark matter can be excluded on theoretical grounds requires an understanding of dense matter that we have not yet reached.
hep-phastro-ph.HEnucl-thEPJ Web Conf.(2018)·8 citations
09*
Generelized parton distributions and the structure of the hadrons
O.V. Selyugin🇷🇺
The dependence of the hadron interaction on its structure is examined in the framework of the generelized parton distributions (GPDs). The x dependence of the GPDs is determined by the parton distribution functions (PDFs), which were obtained from the deep inelastic scattering. The analysis of the whole sets of experimental data on the electromagnetic form factors of the proton and neutron with taking into account many forms of PDFs, obtained by the different Collaborations, make it possible to obtain the special momentum transfer dependence of the GPDs. This permits us to obtain the electromagnetic and gravitomagnetic form factors of the nucleons. The impact parameter dependence of the proton and neutron charge and matter densities is examined. The elastic hadron scattering at high energies was analyzed in the framework of the model that takes into account both these form factors (electromagnetic and gravitomagnetic).
hep-phInt.J.Mod.Phys.Conf.Ser.(2018)·0 citations
10*
Analytic representation of $F_{K} / F_{π}$ in two loop chiral perturbation theory
B. Ananthanarayan🇮🇳 · Johan Bijnens🇸🇪 · Samuel Friot🇫🇷 · Shayan Ghosh🇮🇳
We present an analytic representation of $F_{K} / F_{π}$ as calculated in three-flavour two-loop chiral perturbation theory, which involves expressing three mass scale sunsets in terms of Kampé de Fériet series. We demonstrate how approximations may be made to obtain relatively compact analytic representations. An illustrative set of fits using lattice data is also presented, which shows good agreement with existing fits.
hep-phPRD(2018)·22 citations
11*
Radiative Dirac neutrino mass, DAMPE dark matter and leptogenesis
Pei-Hong Gu🇨🇳
We explain the electron-positron excess reported by the DAMPE collaboration recently in a radiative Dirac seesaw model where a dark $U (1)_{X}$ gauge symmetry can (i) forbid the tree-level Yukawa couplings of three right-handed neutrinos to the standard model lepton and Higgs doublets, (ii) predict the existence of three dark fermions for the gauge anomaly cancellation, (iii) mediate a testable scattering of the lightest dark fermion off the nucleons. Our model can also accommodate a successful leptogenesis to generate the cosmic baryon asymmetry.
hep-ph34 citations
12*
First determination of $D^{*+}$ -meson fragmentation functions and their uncertainties at next-to-next-to-leading order
Maryam Soleymaninia🇮🇷 · Hamzeh Khanpour🇮🇷 · S. Mohammad Moosavi Nejad🇮🇷
We present, for the first time, a set of next-to-next-to-leading order (NNLO) fragmentation functions (FFs) describing the production of charmed-meson $D^{*+}$ from partons. Exploiting the universality and scaling violations of FFs, we extract the NLO and NNLO FFs through a global fit to all relevant data sets from single-inclusive $e^{+} e^{-}$ annihilation. The uncertainties for the resulting FFs as well as the corresponding observables are estimated using the Hessian approach. We evaluate the quality of the {\tt SKM18} FFs determined in this analysis by comparing with the recent results in literature and show how they describe the available data for single-inclusive $D^{*+}$ -meson production in electron-positron annihilation. As a practical application, we apply the extracted FFs to make our theoretical predictions for the scaled-energy distributions of $D^{*+}$ -mesons inclusively produced in top quark decays. We explore the implications of {\tt SKM18} for LHC phenomenology and show that our findings of this study can be introduced as a channel to indirect search for top-quark properties.
hep-phhep-exPRD(2018)·43 citations
13*
Saturation model of DIS : an update
Krzysztof Golec-Biernat🇵🇱 · Sebastian Sapeta🇵🇱
We present the results of new fits to the recently extracted data on $F_{2}$ at low $x$ with the GBW saturation model and its modification to cover high values of $Q^{2}$ . We find that the model stands the test of time and gives a good description of the data with slightly modified parameters. All the essential elements of the model, especially the saturation scale, are retained.
hep-phJHEP(2018)·100 citations
14*
Model-independent analysis of the DAMPE excess
Peter Athron🇦🇺 · Csaba Balazs🇦🇺 · Andrew Fowlie🇦🇺 · Yang Zhang🇦🇺
The Dark Matter Particle Explorer (DAMPE) recently released measurements of the electron spectrum with a hint of a narrow peak at about 1.4 TeV. We investigate dark matter (DM) models that could produce such a signal by annihilation in a nearby subhalo whilst simultaneously satisfying constraints from DM searches. In our model-independent approach, we consider all renormalizable interactions via a spin 0 or 1 mediator between spin 0 or 1/2 DM particles and the Standard Model leptons. We find that of the 20 combinations, 10 are ruled out by velocity or helicity suppression of the annihilation cross section to fermions. The remaining 10 models, though, evade constraints from the relic density, collider and direct detection searches, and include models of spin 0 and 1/2 DM coupling to a spin 0 or 1 mediator. We delineate the regions of mediator mass and couplings that could explain the DAMPE excess. In all cases the mediator is required to be heaver than about 2 TeV by LEP limits.
hep-phastro-ph.HEJHEP(2018)·57 citations
15*
Roadmap of left-right models based on GUTs
Joydeep Chakrabortty🇮🇳 · Rinku Maji🇮🇳 · Subhendra Mohanty🇮🇳 · Sunando Kumar Patra🇮🇳 · Tripurari Srivastava🇮🇳
We perform a detailed study of the grand unified theories $S O (10)$ and $E (6)$ with left-right intermediate gauge symmetries of the form $S U (N)_{L} \otimes S U (N)_{R} \otimes G$ . Proton decay lifetime constrains the unification scale to be $≳ 1 0^{16}$ GeV and, as discussed in this paper, unwanted cosmological relics can be evaded if the intermediate symmetry scale is $≳ 1 0^{12}$ GeV. With these conditions, we study the renormalization group evolution of the gauge couplings and do a comparative analysis of all possible left-right models where unification can occur. Both the D-parity conserved and broken scenarios, as well as the supersymmetric (SUSY) and Non-supersymmetric (Non-SUSY) versions, are considered. In addition to the fermion and scalar representations at each stage of the symmetry breaking, contributing to the $β$ -functions, we list the intermediate left-right groups which successfully meet these requirements. We make use of the dimension-5 kinetic mixing effective operators for achieving unification and large intermediate scale. A significant result in the supersymmetric case is that to achieve successful unification for some breaking patterns, the scale of SUSY breaking needs to be at least a few TeV. In some of these cases, the intermediate scale can be as low as $\sim 1 0^{12}$ GeV, for SUSY scale to be $\sim 30$ TeV. This has important consequences in the collider searches for SUSY particles and phenomenology of the lightest neutralino as dark matter.
hep-phPRD(2018)·46 citations
16*
Scalar dark matter interpretation of the DAMPE data with U(1) gauge interactions
Junjie Cao🇨🇳 · Lei Feng🇨🇳 · Xiaofei Guo🇨🇳 · Liangliang Shang🇨🇳 · Fei Wang🇨🇳 · Peiwen Wu🇰🇷
Recently, DAMPE experiment released the new measurement of the total cosmic $e^{+} e^{-}$ flux between 25 GeV and 4.6 TeV which indicates a spectral softening at around 0.9 TeV and a tentative peak at around 1.4 TeV. We utilize the scalar dark matter (DM) annihilation scenario to explain the DAMPE peak by extending $G_{S M} \equiv S U (3)_{C} \times S U (2)_{L} \times U (1)_{Y}$ with additional $U (1)$ gauge symmetries while keeping anomaly free to generate $χχ \to Z^{'} Z^{'} \to ℓ ℓ ˉ ℓ^{'} ℓ^{'}$ , where $χ, Z^{'}, ℓ^{(^{'})}$ denote the scalar DM, the new gauge boson and $ℓ^{(^{'})} = e, μ, τ$ , respectively, with $m_{χ} \sim m_{Z^{'}} \sim 2 \times 1.5$ (TeV). We first illustrate that the minimal framework $G_{S M} \times U (1)_{Y^{'}}$ with the above mass choices can explain the DAMPE excess but has been excluded by LHC constraints from the $Z^{'}$ searches. Then we study a non-minimal framework $G_{S M} \times U (1)_{Y^{'}} \times U (1)_{Y^{''}}$ in which $U (1)_{Y^{''}}$ mixes with $U (1)_{Y^{'}}$ . We show that such a framework can interpret the DAMPE data while passing other constraints including the DM relic abundance, DM direct detection and collider bounds. We also investigate the predicted $e^{+} e^{-}$ spectrum in this framework and find that the mass splitting $Δ m = m_{χ} - m_{Z^{'}}$ should be less than about 17 GeV to produce the peak-like structure.
hep-phastro-ph.HEPRD(2018)·45 citations
17*
Dark matter, extra-terrestrial gamma-rays and the MSSM: a viability study
Arpan Kar🇮🇳 · Sourav Mitra🇮🇳 · Biswarup Mukhopadhyaya🇮🇳 · Tirthankar Roy Choudhury🇮🇳
We fit the $γ$ -ray excess from the galactic centre (GC) in terms of parameters of the minimal supersymmetric standard model (MSSM). Consistency with other $γ$ -ray observation, such as those from dwarf spheroidal galaxies, is also ensured, in addition to the constraints from direct dark matter search. Furthermore, we expect the contribution to the relic density from the MSSM dark mater candidate, namely, the lightest neutralino, should not go below the stipulated value; otherwise it will amount to going beyond the MSSM by including some additional dark matter source. After a detailed scan of the parameter space in terms of four representative types of particle spectra, we identify the ones that are best fit to the observed data. However, these two are somewhat unsatisfactory in terms of $χ_{min}^{2}$ as well as $p$ -values. In some case(s), the unacceptability of low- $χ_{min}^{2}$ regions due to direct search constraint is responsible for this. In others, the observed shape of the $γ$ -ray spectrum makes the fits unsatisfactory. The imposed lower limit on relic density, too, has a role to play all along. On the whole, the conclusion is that the MSSM is not a very satisfactory fit for the GC $γ$ -ray compounded with other cosmological observations and direct search limits.
hep-phastro-ph.HEJCAP(2018)·2 citations
18*
Spectroscopy of the All-Charm Tetraquark
V. R. Debastiani🇪🇸 · F. S. Navarra🇧🇷
We use a non-relativistic model to study the mass spectroscopy of a tetraquark composed by $c c ˉ c c ˉ$ quarks in the diquark-antidiquark picture. By numerically solving the Schrödinger equation with a Cornell-inspired potential, we separate the four-body problem into three two-body problems. Spin-dependent terms (spin-spin, spin-orbit and tensor) are used to describe the splitting structure of the $c c ˉ$ spectrum and are also extended to the interaction between diquarks. Recent experimental data on charmonium states are used to fix the parameters of the model and a satisfactory description of the spectrum is obtained. We find that the spin-dependent interaction is sizable in the diquark-antidiquark system, despite of the heavy diquark mass, and that the diquark has a finite size if treated in analogy to the $c c ˉ$ systems. We find that the lowest $S$ -wave $T_{4 c}$ tetraquarks might be below their thresholds of spontaneous dissociation into low-lying charmonium pairs, while orbital and radial excitations would be mostly above the corresponding charmonium pair threshold. These states could be investigated in the forthcoming experiments at LHCb and Belle II.
hep-phPoS(2018)·4 citations
19*
Scalar form factors of semi-leptonic $D \to π / K ˉ$ transitions with coupled-channel effects
De-Liang Yao🇪🇸 · Miguel Albaladejo🇪🇸 · Pedro Fernández-Soler🇪🇸 · Feng-Kun Guo🇨🇳 · Juan Nieves🇪🇸
Coupled-channel effects are taken into account for the study of scalar form factors in semi-leptonic $D \to π ℓ ˉ ν_{ℓ}$ and $D \to K ˉ ℓ ˉ ν_{ℓ}$ decays, by solving the Muskhelishvili-Omnès integral equations. As inputs, we employ the unitarized amplitudes taken from chiral effective theory for the region not far away from thresholds, while, at higher energies of the Goldstone bosons, proper asymptotic conditions are employed. Within Muskhelishvili-Omnès formalism, the scalar form factors are represented in terms of Omnès matrix multiplied by a vector of polynomials. We reduce the number of subtraction constants by matching to the scalar form factors derived in chiral perturbation theory up to next-to-leading order. The recent lattice QCD data by ETM collaboration for $D \to π$ and $D \to K ˉ$ scalar form factors are simultaneously well described. The scalar form factors for $D \to η$ , $D_{s} \to K ˉ$ and $D_{s} \to η$ transitions are predicted in their whole kinematical regions. Using our fitting parameters, we also extract the following Cabibbo-Kobayashi-Maskawa elements: $∣ V_{c d} ∣ = 0.243 (_{- 12}^{+ 11})_{sta.} (3)_{sys.} (3)_{exp.}$ and $∣ V_{cs} ∣ = 0.950 (_{- 40}^{+ 39})_{sta.} (1)_{sys.} (7)_{exp.}$ . The approach used in this work can be straightforwardly extended to the semileptonic $B$ decays.
hep-phPoS(2018)·4 citations
20*
Electroweak Phase Transition in Scale Invariant Standard Model
Parsa Hossein Ghorbani🇮🇷
In an extension to the scale invariant standard model by two real singlet scalars $s$ and $s^{'}$ in addition to the Higgs field, we investigate the strong first-order electroweak phase transition as a requirement for baryogenesis. This is the minimal extension to the scale invariant standard model with two extra degrees of freedom that possesses the physical Higgs mass of $125$ GeV. The scalar $s^{'}$ being stable because of the $Z_{2}$ discrete symmetry is taken as the dark matter candidate. We then show that the electroweak phase transition is strongly first-order, the dark matter relic density takes the desired value $Ω_{DM} h^{2} \sim 0.11$ , and the constraints from direct detection experiments are respected only if $m_{s^{'}} \equiv m_{DM} ≳ 4.5$ TeV. The model also puts a lower bound on the scalon mass, $m_{s} ≳ 200$ GeV.
hep-phPRD(2018)·24 citations
21*
A Nakanishi-based model illustrating the covariant extension of the pion GPD overlap representation and its ambiguities
N. Chouika🇫🇷 · C. Mezrag🇮🇹 · H. Moutarde🇫🇷 · J. Rodríguez-Quintero🇪🇸
A systematic approach for the model building of Generalized Parton Distributions (GPDs), based on their overlap representation within the DGLAP kinematic region and a further covariant extension to the ERBL one, is applied to the valence-quark pion's case, using light-front wave functions inspired by the Nakanishi representation of the pion's Bethe-Salpeter amplitudes (BSA). This simple but fruitful pion's GPD model illustrates the general model building technique and, in addition, allows for the ambiguities related to the covariant extension, grounded on the Double Distribution (DD) representation, to be constrained by requiring a soft-pion theorem to be properly observed.
hep-phnucl-thPLB(2018)·60 citations
22*
The structure, mixing angle, mass and couplings of the light scalar $f_{0} (500)$ and $f_{0} (980)$ mesons
S. S. Agaev🇦🇿 · K. Azizi🇹🇷 · H. Sundu🇹🇷
The mixing angle, mass and couplings of the light scalar mesons $f_{0} (500)$ and $f_{0} (980)$ are calculated in the framework of QCD two-point sum rule approach by assuming that they are tetraquarks with diquark-antidiquark structures. The mesons are treated as mixtures of the heavy $∣ H ⟩ = ([s u] [s ˉ u ˉ] + [s d] [s ˉ d ˉ]) / 2$ and light $∣ L ⟩ = [u d] [u ˉ d ˉ]$ scalar diquark-antidiquark components. We extract from corresponding sum rules the mixing angles $φ_{H}$ and $φ_{L}$ of these states and evaluate the masses and couplings of the particles $f_{0} (500)$ and $f_{0} (980)$ .
hep-phhep-exhep-latPLB(2018)·17 citations
23*
QCD-induced Electroweak Phase Transition
Benedict von Harling🇩🇪 · Geraldine Servant🇩🇪
Phase transitions associated with nearly conformal dynamics are known to lead to significant supercooling. A notorious example is the phase transition in Randall-Sundrum models or their CFT duals. In fact, it was found that the phase transition in this case is first-order and the tunneling probability for the radion/dilaton is so small that the system typically remains trapped in the false vacuum and the phase transition never completes. The universe then keeps expanding and cooling. Eventually the temperature drops below the QCD scale. We show that the QCD condensates which subsequently form give an additional contribution to the radion/dilaton potential, an effect which had been ignored so far. This significantly reduces the barrier in the potential and allows the phase transition to complete in a substantially larger region of parameter space. Due to the supercooling, electroweak symmetry is then broken simultaneously. This class of models therefore naturally leads to an electroweak phase transition taking place at or below QCD temperatures, with interesting cosmological implications and signatures.
hep-phJHEP(2018)·179 citations
24*
Leptophilic dark matter in gauged $U (1)_{L_{e} - L_{μ}}$ model in light of DAMPE cosmic ray $e^{+} + e^{-}$ excess
Guang Hua Duan🇨🇳 · Xiao-Gang He🇹🇼 · Lei Wu🇨🇳 · Jin Min Yang🇨🇳
Motivated by the very recent cosmic-ray electron+positron excess observed by DAMPE collaboration, we investigate a Dirac fermion dark matter (DM) in the gauged $L_{e} - L_{μ}$ model. DM interacts with the electron and muon via the $U (1)_{e - μ}$ gauge boson $Z^{^{'}}$ . The model can explain the DAMPE data well. Although a non-zero DM-nucleon cross section is only generated at one loop level and there is a partial cancellation between $Z^{^{'}} ee$ and $Z^{^{'}} μμ$ couplings, we find that a large portion of $Z^{^{'}}$ mass is ruled out from direct DM detection limit leaving the allowed $Z^{^{'}}$ mass to be close to two times of the DM mass. Implications for $pp \to Z^{^{'}} \to 2 ℓ$ and $pp \to 2 ℓ + Z^{^{'}}$ , and muon $g - 2$ anomaly are also studied.
hep-phEPJC(2018)·53 citations
25*
Muon g-2 in the 2HDM: maximum results and detailed phenomenology
Adriano Cherchiglia🇧🇷 · Dominik Stöckinger🇩🇪 · Hyejung Stöckinger-Kim🇩🇪
We present a comprehensive analysis of the muon magnetic moment $a_{μ}$ in the flavour-aligned two-Higgs doublet model (2HDM) and parameter constraints relevant for $a_{μ}$ . We employ a recent full two-loop computation of $a_{μ}$ and take into account experimental constraints from Higgs and flavour physics on the parameter space. Large $a_{μ}$ is possible for light pseudoscalar Higgs A with large Yukawa couplings to leptons, and it can be further increased by large A coupling to top quarks. We investigate in detail the maximum possible Yukawa couplings to leptons and quarks of a light A, finding values of around 50...100 (leptons) and O(0.5) (quarks). As a result we find that an overall maximum of $a_{μ}$ in the 2HDM of more than $45 \times 1 0^{- 10}$ is possible in a very small parameter region around M_A=20 GeV. The parameter regions in which the currently observed deviation can be explained are characterized.
hep-phPRD(2018)·78 citations
26*
Top Quark Production and Decay in Herwig 7.1
Johannes Bellm🇸🇪 · Kyle Cormier🇨🇦 · Stefan Gieseke🇩🇪 · Simon Plätzer🇦🇹 · Christian Reuschle🇺🇸 · Peter Richardson🇨🇭 · Stephen Webster🇬🇧
A summary of recent developments in the simulation of top quark production and decay in the Herwig Monte Carlo event generator.
hep-ph9 citations
27*
Corrections to the higher moments of the relativistic ion energy-loss distribution beyond the Born approximation. I. Z dependence of Mott's corrections
O. Voskresenskaya🇷🇺
Using the Mott exact cross section for moderate relativistic energies, we calculated the corrections to the first-order Born higher moments of the energy-loss distribution of charged particles in a wide range of the particle charge numbers.
hep-phnucl-th4 citations
28*
TeV dark matter and the DAMPE electron excess
Xuewen Liu🇨🇳 · Zuowei Liu🇨🇳
The recent high energy electron and positron flux observed by the DAMPE experiment indicates possible excess events near 1.4 TeV. Such an excess may be evidence of dark matter annihilations or decays in a dark matter subhalo that is located close to the solar system. We give here an analysis of this excess from annihilations of Dirac fermion dark matter which is charged under a new $U (1)_{X}$ gauge symmetry. The interactions between dark matter and the standard model particles are mediated the $U (1)_{X}$ gauge boson. We show that dark matter annihilations from a local subhalo can explain the excess with the canonical thermal annihilation cross section. We further discuss the constraints from the relic density, from the dark matter direct detection, from the dark matter indirect detection, from the cosmic microwave background, and from the particle colliders.
hep-phastro-ph.HEPRD(2018)·46 citations
29*
Charmed-baryon production in antiproton-proton collisions within an effective Lagrangian model
R. Shyam🇮🇳
We study the productions of charmed baryons $Λ ˉ_{c}^{-} Λ_{c}^{+}$ , $Λ ˉ_{c}^{-} Σ_{c}^{+}$ , and $Σ ˉ^{-} Σ_{c}^{+}$ in the antiproton-proton collisions within an effective Lagrangian model that has only the baryon-meson degrees of freedom and involves the physical hadron masses. The baryon production proceeds via the $t$ -channel exchanges of $D^{0}$ and $D^{* 0}$ mesons in the initial collision of the antiproton with the target proton. The distortion effects in the initial and final states are accounted for by using an eikonal approximation-based procedure. We find that the reaction amplitudes of all the production channels are dominated by the $D^{* 0}$ meson-exchange diagrams. We discuss the relative roles of tensor and vector components of the $D^{* 0}$ coupling in the $D^{* 0}$ meson-exchange component of the total production cross sections. The magnitudes of the cross sections are predicted for each final state for the range of beam momenta of relevance to the $P ˉ A N D A$ experiment.
hep-phhep-exnucl-exnucl-thPRD(2017)·6 citations
30*
First-order classical Lagrangians for the nonminimal Standard-Model Extension
J.A.A.S. Reis🇧🇷 · M. Schreck🇧🇷
In this paper, we derive the general leading-order classical Lagrangian covering all fermion operators of the nonminimal Standard-Model Extension (SME). Such a Lagrangian is considered to be the point-particle analog of the effective field theory description of Lorentz violation that is provided by the SME. First of all, a suitable Ansatz is made for the Lagrangian of the spin-degenerate operators $a^$ , $c^$ , $e^$ , and $f^$ at leading order in Lorentz violation. The latter is shown to satisfy the set of five nonlinear equations that govern the map from the field theory to the classical description. After doing so, the second step is to propose results for the spin-nondegenerate operators $b^$ , $d^$ , $H^$ , and $g^$ . Although these are more involved than the Lagrangians for the spin-degenerate ones, an analytical proof of their validity is viable, nevertheless. The final step is to combine both findings to produce a generic Lagrangian for the complete set of Lorentz-violating operators that is consistent with the known minimal and nonminimal Lagrangians found in the literature so far. The outcome reveals the leading-order structure of the classical SME analog. It can be of use for both phenomenological studies of classical bodies in gravitational fields and conceptual work on explicit Lorentz violation in gravity. Furthermore, there may be a possible connection to Finsler geometry.
↳ hep-thhep-phPRD(2018)·21 citations
31*
Unidirectional Random Growth with Resetting
Tamas S Biro🇭🇺 · Zoltan Neda🇷🇴
We review and classify stochastic processes without detailed balance condition. We obtain stationary distributions and investigate their stability in terms of generalized entropic divergences beyond the Kullback-Leibler formula. A simple stochastic model with local growth rates and direct resetting to the ground state is investigated and applied to various networks, scientific citations and Facebook popularity, hadronic yields in high energy particle reactions, income and wealth distributions, biodiversity and settlement size distribution.
↳ physics.soc-phcond-mat.dis-nnhep-phPhysica A(2018)·4 citations
32*
Fitting and selecting scattering data
Enrique Ruiz Arriola🇪🇸 · Jose Enrique Amaro🇪🇸 · Rodrigo Navarro Perez🇺🇸
The main purpose of scattering experiments is to unveil the underlying structure of the colliding particles and their interaction. Typically one measures scattering observables (cross sections and polarizations) at discrete angles and energies and mutually consistent data may validate or falsify proposed theories or models. However, the accumulation of data from different laboratories while potentially improves the statistical significance it may sometimes generate mutually inconsistent data as a side-effect. Thus, some decision has to be made on what are the maximal amount of data which are mutually compatible. We show elastic $π N$ and $N N$ scattering as prominent examples where this selection is called for. We discuss how it can be done in a self-consistent manner invoking a principle of maximal consensus of the database and with the help of a sufficiently flexible model involving a minimal number of theoretical assumptions. In the NN case this has become possible with a combination of long distance field theoretical constraints at the hadronic level such as pion exchanges and electromagnetic effects and a coarse graining of the unknown interaction over the shortest de Broglie wavelength being probed in the scattering process.
↳ nucl-thhep-phnucl-exPoS(2018)·3 citations
33*
Studies of mesic atoms and nuclei
Eliahu Friedman🇮🇱 · Avraham Gal🇮🇱 · Aleš Cieplý🇨🇿 · Jaroslava Hrtánková🇨🇿 · Jiří Mareš🇨🇿
$K^{-}$ mesons offer a unique setting where mesic atoms have been studied both experimentally and theoretically, thereby placing constraints on the possible existence and properties of meson-nuclear quasibound states. Here we review progress in this field made recently by the Jerusalem--Prague Collaboration using near-threshold $K^{-} N$ scattering amplitudes generated in several meson--baryon coupled channels models inspired by a chiral EFT approach. Our own procedure of handling subthreshold kinematics self consistently is used to transform these free-space energy dependent amplitudes to in-medium density dependent amplitudes from which $K^{-}$ optical potentials are derived. To fit the world data of kaonic atoms, these single-nucleon optical potentials are augmented by multi-nucleon terms. It is found that only two of the studied models reproduce also the single-nucleon absorption fractions available from old bubble chamber experiments. These two models are then checked for possible $K^{-}$ nuclear quasibound states, despite realizing that $K^{-}$ optical potentials are not constrained by kaonic atom data at densities exceeding half nuclear-matter density. We find that when such states exist, their widths are invariably above 100 MeV, forbiddingly large to allow observation. Multi-nucleon absorption is found to be substantial in this respect. This suggests that observable strongly bound $K^{-}$ mesons are limited to the very light systems, such as $K^{-} pp$ .
↳ nucl-thhep-phnucl-exPoS(2018)·4 citations
34*
An Update on Brane Supersymmetry Breaking
J. Mourad🇫🇷 · A. Sagnotti🇮🇹
"Brane supersymmetry breaking" is a peculiar phenomenon that can occur in perturbative orientifold vacua. It results from the simultaneous presence, in the vacuum, of non-mutually BPS sets of BPS branes and orientifolds, which leave behind a net tension and thus a runaway potential, but no tachyons. In the simplest ten-dimensional realization, the low-lying modes combine the closed sector of type-I supergravity with an open sector including USp(32) gauge bosons, fermions in the antisymmetric 495 and an additional singlet playing the role of a goldstino. We review some properties of this system and of other non-tachyonic models in ten dimensions with broken supersymmetry, and we illustrate some puzzles that their very existence raises, together with some applications that they have stimulated.
↳ hep-thastro-ph.COgr-qchep-ph71 citations
35*
Does Anisotropic "Inflation" Produce a Small Statistical Anisotropy?
Tomohiro Fujita🇯🇵 · Ippei Obata🇯🇵
Anisotropic inflation is an interesting model with an U(1) gauge field and it predicts the statistical anisotropy of the curvature perturbation characterized by a parameter $g_{*}$ . However, we find that the background gauge field does not follow the classical attractor solution due to the stochastic effect. We develop the stochastic formalism of a vector field and solve Langevin and Fokker-Planck equations. It is shown that this model is excluded by the CMB constraint $g_{*} \leq 1 0^{- 2}$ with a high probability about $99.999%$ .
↳ astro-ph.COgr-qchep-phhep-thJCAP(2018)·41 citations
36*
Comprehensive Study of Observables in Compton Scattering on the Nucleon
Harald W. Griesshammer (George Washington U.)🇺🇸 · Judith A. McGovern (U. of Manchester)🇬🇧 · Daniel R. Phillips (Ohio U.)🇺🇸
We present an analysis of $13$ observables in Compton scattering on the proton. Cross sections, asymmetries with polarised beam and/or targets, and polarisation-transfer observables are investigated for energies up to the $Δ (1232)$ resonance to determine their sensitivity to the proton's dipole scalar and spin polarisabilities. The Chiral Effective Field Theory Compton amplitude we use is complete at N $^{4}$ LO, $O (e^{2} δ^{4})$ , for photon energies $ω \sim m_{π}$ , and so has an accuracy of a few per cent there. At photon energies in the resonance region it is complete at NLO, $O (e^{2} δ^{0})$ , and so its accuracy there is about $20$ \%. We find that for energies from pion-production threshold to about $250 MeV$ , multiple asymmetries have significant sensitivity to presently ill-determined combinations of proton spin polarisabilities. We also argue that the broad outcomes of this analysis will be replicated in complementary theoretical approaches, e.g., dispersion relations. Finally, we show that below the pion-production threshold, $6$ observables suffice to reconstruct the Compton amplitude, and above it $11$ are required. Although not necessary for polarisability extractions, this opens the possibility to perform "complete" Compton-scattering experiments. An interactive Mathematica notebook, including results for the neutron, is available from judith.mcgovern@manchester.ac.uk .
↳ nucl-thhep-phnucl-exEPJA(2018)·16 citations
37*
Non-perturbative Approach to Equation of State and Collective Modes of the QGP
Shuai Y.F. Liu🇺🇸 · Ralf Rapp🇺🇸
We discuss a non-perturbative $T$ -matrix approach to investigate the microscopic structure of the quark-gluon plasma (QGP). Utilizing an effective Hamiltonian which includes both light- and heavy-parton degrees of freedoms. The basic two-body interaction includes color-Coulomb and confining contributions in all available color channels, and is constrained by lattice-QCD data for the heavy-quark free energy. The in-medium $T$ -matrices and parton spectral functions are computed selfconsistently with full account of off-shell properties encoded in large scattering widths. We apply the $T$ -matrices to calculate the equation of state (EoS) for the QGP, including a ladder resummation of the Luttinger-Ward functional using a matrix-log technique to account for the dynamical formation of bound states. It turns out that the latter become the dominant degrees of freedom in the EoS at low QGP temperatures indicating a transition from parton to hadron degrees of freedom. The calculated spectral properties of one- and two-body states confirm this picture, where large parton scattering rates dissolve the parton quasiparticle structures while broad resonances start to form as the pseudocritical temperature is approached from above. Further calculations of transport coefficients reveal a small viscosity and heavy-quark diffusion coefficient.
↳ nucl-thhep-phEPJ Web Conf.(2018)·2 citations
38*
A Precision Search for WIMPs with Charged Cosmic Rays
Annika Reinert🇩🇪 · Martin Wolfgang Winkler🇸🇪
AMS-02 has reached the sensitivity to probe canonical thermal WIMPs by their annihilation into antiprotons. Due to the high precision of the data, uncertainties in the astrophysical background have become the most limiting factor for indirect dark matter detection. In this work we systematically quantify and -- where possible -- reduce uncertainties in the antiproton background. We constrain the propagation of charged cosmic rays through the combination of antiproton, B/C and positron data. Cross section uncertainties are determined from a wide collection of accelerator data and are -- for the first time ever -- fully taken into account. This allows us to robustly constrain even subdominant dark matter signals through their spectral properties. For a standard NFW dark matter profile we are able to exclude thermal WIMPs with masses up to 570 GeV which annihilate into bottom quarks. While we confirm a reported excess compatible with dark matter of mass around 80 GeV, its local (global) significance only reaches 2.2 sigma (1.1 sigma) in our analysis.
↳ astro-ph.HEhep-phJCAP(2018)·172 citations
39*
Origins of sharp cosmic-ray electron structures and the DAMPE excess
Xian-Jun Huang🇨🇳 · Yue-Liang Wu🇨🇳 · Wei-Hong Zhang🇨🇳 · Yu-Feng Zhou🇨🇳
Nearby sources may contribute to cosmic-ray electron (CRE) structures at high energies. Recently, the first DAMPE results on the CRE flux hinted at a narrow excess at energy ~1.4 TeV. We show that in general a spectral structure with a narrow width appears in two scenarios: I) "Spectrum broadening" for the continuous sources with a delta-function-like injection spectrum. In this scenario, a finite width can develop after propagation through the Galaxy, which can reveal the distance of the source. Well-motivated sources include mini-spikes and subhalos formed by dark matter (DM) particles $χ_{s}$ which annihilate directly into e+e- pairs. II) "Phase-space shrinking" for burst-like sources with a power-law-like injection spectrum. The spectrum after propagation can shrink at a cooling-related cutoff energy and form a sharp spectral peak. The peak can be more prominent due to the energy-dependent diffusion. In this scenario, the width of the excess constrains both the power index and the distance of the source. Possible such sources are pulsar wind nebulae (PWNe) and supernova remnants (SNRs). We analysis the DAMPE excess and find that the continuous DM sources should be fairly close within ~0.3 kpc, and the annihilation cross sections are close to the thermal value. For the burst-like source, the narrow width of the excess suggests that the injection spectrum must be hard with power index significantly less than two, the distance is within ~(3-4) kpc, and the age of the source is ~0.16 Myr. In both scenarios, large anisotropies in the CRE flux are predicted. We identify possible candidates of mini-spike (PWN) sources in the current Fermi-LAT 3FGL (ATNF) catalog. The diffuse gamma-rays from these sources can be well below the Galactic diffuse gamma-ray backgrounds and less constrained by the Ferm-LAT data, if they are located at the low Galactic latitude regions.
↳ astro-ph.HEhep-phPRD(2018)·51 citations
40*
Features in the Spectrum of Cosmic-Ray Positrons from Pulsars
Ilias Cholis🇺🇸 · Tanvi Karwal🇺🇸 · Marc Kamionkowski🇺🇸
Pulsars have been invoked to explain the origin of recently observed high-energy Galactic cosmic-ray positrons. Since the positron propagation distance decreases with energy, the number of pulsars that can contribute to the observed positrons decreases from $O (1 0^{3})$ for positron energies $E ≳ 10$ GeV to only a few for $E ≳ 500$ GeV. Thus, if pulsars explain these positrons, the positron energy spectrum should become increasingly bumpy at higher energies. Here we present a power-spectrum analysis that can be applied to seek such spectral features in the energy spectrum for cosmic-ray positrons and for the energy spectrum of the combined electron/positron flux. We account for uncertainties in the pulsar distribution by generating hundreds of simulated spectra from pulsar distributions consistent with current observational constraints. Although the current AMS-02 data do not exhibit evidence for spectral features, we find that such features would be detectable in $≃ 10%$ of our simulations, with 20 years of AMS-02 data or three years of DAMPE measurements on the electron-plus-positron flux.
↳ astro-ph.HEastro-ph.IMhep-phPRD(2018)·32 citations
41*
First study of reionization in the Planck 2015 normalized closed $Λ$ CDM inflation model
Sourav Mitra🇮🇳 · Tirthankar Roy Choudhury🇮🇳 · Bharat Ratra🇺🇸
We study reionization in two non-flat $Λ$ CDM inflation models that best fit the Planck 2015 cosmic microwave background anisotropy observations, ignoring or in conjunction with baryon acoustic oscillation distance measurements. We implement a principal component analysis (PCA) to estimate the uncertainties in the reionization history from a joint quasar-CMB dataset. A thorough Markov Chain Monte Carlo analysis is done over the parameter space of PCA modes for both non-flat $Λ$ CDM inflation models as well as the original Planck 2016 tilted, spatially-flat $Λ$ CDM inflation model. Although both flat and non-flat models can closely match the low-redshift ( $z ≲ 6$ ) observations, we notice a possible tension between high-redshift ( $z \sim 8$ ) Lyman- $α$ emitter data and the non-flat models. This is solely due to the fact that the closed models have a relatively higher reionization optical depth compared to the flat one, which in turn demands more high-redshift ionizing sources and favors an extended reionization starting as early as $z \approx 14$ . We conclude that as opposed to flat-cosmology, for the non-flat cosmology models (i) the escape fraction needs steep redshift evolution and even unrealistically high values at some redshifts and (ii) most of the physical parameters require to have non-monotonic redshift evolution, especially apparent when Lyman- $α$ emitter data is included in the analysis.
↳ astro-ph.COgr-qchep-phhep-thMNRAS(2018)·34 citations
42*
Cosmic ray $e^{+} e^{-}$ spectrum excess and peak feature observed by the DAMPE experiment from dark matter
Hong-Bo Jin🇨🇳 · Bin Yue🇨🇳 · Xin Zhang🇨🇳 · Xuelei Chen🇨🇳
The Chinese satellite Wukong, also known as the DArk Matter Particle Explorer (DAMPE), has released its observation data of the cosmic ray (CR) electrons and positrons. The data shows an excess in the energy spectrum up to TeV energy, and possibly a peak-like fine structure at $\sim 1.4 \TeV$ . We investigate the scenario that the source of the excess comes from dark matter annihilation or decay. We find that the annihilation or decay of diffuse dark matter particles in the Galactic halo can give excellent ( $W^{+} W^{-}$ channel) or at least good (double $τ^{+} τ^{-}$ channel) fits to the broad excess. However, the annihilation cross-section is $1 0^{- 23} \cm^{3} s^{- 1}$ , larger than required for getting the correct relic abundance. We then study whether the narrow peak at $\sim 1.4 \TeV$ could be explained by a nearby subhalo, which thanks to the smaller distance, could supply $e^{+} e^{-}$ within a narrow energy range. We find that in order to produce a peak width less than the energy bin width (0.2 TeV), the source must be located within $r \lsim 0.53 \kpc$ . Our global fit models do not produce the peak-like feature, instead at 1.4 TeV the spectrum show either a slope or a cliff-like feature. However, if less than optimal fit is allowed, the peak-like feature could be generated. Furthermore, an excellent fit with peak could be obtained with model B if the background is rescaled. If the dark matter decay and annihilation rates are determined using the broad excess, the required subhalo mass $\sim 1 0^{5} M_{⊙}$ for decay model, or $\sim 1 0^{4.5} \Msun$ for annihilation model and a shallower density profile slope $α = 1.2$ , or $\sim 1 0^{2.5} \Msun$ for the steep density profile $α = 1.7$ . However, the probability for the existence of a such nearby subhalo as massive as given above is very low.
↳ astro-ph.HEhep-phPRD(2018)·35 citations
43*
Implications of dark matter cascade decay from DAMPE, HESS, Fermi-LAT and AMS02 data
Yu Gao🇨🇳 · Yin-Zhe Ma🇿🇦
Recent high-energy cosmic $e^{\pm}$ measurement from the DArk Matter Particle Explorer (DAMPE) satellite confirms the deviation of total cosmic ray electron spectrum above 700-900 GeV from a simple power law. In this paper we demonstrate that the cascade decay of dark matter (DM) can account for DAMPE's TeV $e^{+} e^{-}$ spectrum. We select the least constraint DM decay channel into four muons as the benchmark scenario, and perform an analysis with propagation variance in both DM signal and the Milky Way's electron background. The best-fit of the model is obtained for joint DAMPE, Fermi-Large Area Telescope (Fermi-LAT), High Energy Stereoscopic System (HESS), high energy electron data sets, and with an $O (1 0^{26})$ second decay lifetime, which is consistent with existing gamma ray and cosmic microwave background limits. We compare the spectral difference between the cascade decay of typical final-state channels. The least constrained $4 μ$ channels give good fits to the electron spectrum's TeV scale down-turn, yet their low energy spectrum has tension with sub-TeV positron data from AMS02. We also consider a three-step cascade decay into eight muons, and also a gamma-ray constrained $4 μ, 4 b$ mixed channel, to demonstrate that a further softened cascade decay signal would be required for the agreement with all the data sets.
↳ astro-ph.HEhep-phMNRAS(2020)·31 citations
44*
Bayesian analysis of the break in DAMPE lepton spectra
Jia-Shu Niu🇨🇳 · Tianjun Li🇨🇳 · Ran Ding🇨🇳 · Bing Zhu🇨🇳 · Hui-Fang Xue🇨🇳 · Yang Wang🇨🇳
Recently, DAMPE has released its first results on the high-energy cosmic-ray electrons and positrons (CREs) from about $25$ GeV to $4.6$ TeV, which directly detect a break at $\sim 1$ TeV. This result gives us an excellent opportunity to study the source of the CREs excess. In this work, we used the data fo proton and helium flux (from AMS-02 and CREAM), $p ˉ / p$ ratio (from AMS-02), positron flux (from AMS-02) and CREs flux (from DAMPE without the peak signal point at $\sim 1.4$ TeV) to do global fitting simultaneously, which can account the influence from the propagation model, the nuclei and electron primary source injection and the secondary lepton production precisely. For extra source to interpret the excess in lepton spectrum, we consider two separate scenarios (pulsar and dark matter annihilation via leptonic channels) to construct the bump ( $≳ 100$ GeV) and the break at $\sim 1$ TeV. The result shows: (i) in pulsar scenario, the spectral index of the injection should be $ν_{psr} \sim 0.65$ and the cut-off should be $R_{c} \sim 650$ GV; (ii) in dark matter scenario, the dark matter particle's mass is $m_{χ} \sim 1208$ GeV and the cross section is $⟨ σ v ⟩ \sim 1.48 \times 1 0^{- 23} cm^{3} s^{- 1}$ . Moreover, in the dark matter scenario, the $τ τ ˉ$ annihilation channel is highly suppressed, and a DM model is built to satisfy the fitting results.
↳ astro-ph.HEhep-phPRD(2018)·38 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.