HEP Phenomenology·hep-ph

Mon·Jan 20, 2020Monday·January 20, 2020

17 papers—14 primary·3 cross-listed·reconstructed*

01*
Dark sector-photon interactions in proton-beam experiments
Xiaoyong Chu🇦🇹 · Jui-Lin Kuo🇦🇹 · Josef Pradler🇦🇹
We consider electromagnetically neutral dark states that couple to the photon through higher dimensional effective operators, such as electric and magnetic dipole moment, anapole moment and charge radius operators. We investigate the possibility of probing the existence of such dark states, taking a Dirac fermion $χ$ as an example, at several representative proton-beam experiments. As no positive signal has been reported, we obtain upper limits (or projected sensitivities) on the corresponding electromagnetic form factors for dark states lighter than several GeV. We demonstrate that while the current limits from proton-beam experiments are at most comparable with those from high-energy electron colliders, future experiments, such as DUNE and SHiP, will be able to improve the sensitivities to electric and magnetic dipole moment interactions, owing to their high intensity.
hep-phPRD(2020)·42 citations
02*
Nucleon form factors from basis light front quantization
Chandan Mondal🇨🇳 · Siqi Xu🇨🇳 · Jiangshan Lan🇨🇳 · Xingbo Zhao🇨🇳 · Yang Li🇺🇸 · Henry Lamm🇺🇸 · James P. Vary🇺🇸
We investigate the electromagnetic form factors of the nucleon in the framework of basis light front quantization. We compute the form factors using the light front wavefunctions obtained by diagonalizing the effective Hamiltonian consisting of the holographic QCD confinement potential, the longitudinal confinement, and a one-gluon exchange interaction with fixed coupling. The electromagnetic radii of the nucleon are also computed.
hep-ph1 citation
03*
Hybrid phenomenology in a chiral approach
Walaa I. Eshraim🇩🇪 · Christian S. Fischer🇩🇪 · Francesco Giacosa🇵🇱 · Denis Parganlija🇦🇹
We calculate masses and decays of the (lightest) hybrid nonet with exotic quantum numbers $J^{P C} = 1^{-+}$ and the nonet of their chiral partners with $J^{P C} = 1^{+-}$ in the framework of the extended Linear Sigma Model (eLSM). As an input, we identify $π_{1}^{h y b} = π_{1} (1600)$ as a low-lying hybrid. We investigated interaction terms which fulfil chiral symmetry. For what concerns $π_{1}^{h y b},$ the most important decays are $π_{1}^{h y b} \to b_{1} π,$ $π_{1} (1600) \to ρ π η,$ $π_{1}^{h y b}$ and $π_{1}^{h y b} \to K K^{*} (892) .$ The decays $π_{1}^{h y b} \to η π$ and $π_{1}^{h y b} \to η^{'} π$ are expected to be small but non-zero: they follow from a chirally symmetric interaction term that breaks explicitly the axial anomaly. For all the other members of the two hybrid nonets (for which no experimental candidates exist yet) we report decay ratios that may guide ongoing and future experiments.
hep-phEur.Phys.J.Plus(2020)·32 citations
04*
Note on all-order Landau-level structures of the Heisenberg-Euler effective actions for QED and QCD
Koichi Hattori🇯🇵 · Kazunori Itakura🇯🇵 · Sho Ozaki🇯🇵
We investigate the Landau-level structures encoded in the famous Heisenberg-Euler (HE) effective action in constant electromagnetic fields. We first discuss the HE effective actions for scalar and spinor QED, and then extend it to the QCD analogue in the covariantly constant chromo-electromagnetic fields. We identify all the Landau levels and the Zeeman energies starting out from the proper-time representations at the one-loop order, and derive the vacuum persistence probability for the Schwinger mechanism in the summation form over independent contributions of the all-order Landau levels. We find an enhancement of the Schwinger mechanism catalyzed by a magnetic field for spinor QED and, in contrast, a stronger exponential suppression for scalar QED due to the "zero-point energy" of the Landau quantization. For QCD, we identify the discretized energy levels of the transverse and longitudinal gluon modes on the basis of their distinct Zeeman energies, and explicitly confirm the cancellation between the longitudinal-gluon and ghost contributions in the Schwinger mechanism. We also discuss the unstable ground state of the perturbative gluon excitations known as the Nielsen-Olesen instability.
hep-phquant-ph9 citations
05*
Precision predictions for $B \to ρ τ ν_{τ}$ and $B \to ω τ ν_{τ}$ in the SM and beyond
Markus Tobias Prim🇩🇪 · Florian Urs Bernlochner🇩🇪 · Dean J. Robinson🇺🇸
We present new precision predictions for semitauonic decays involving $ρ$ and $ω$ final state mesons. These decay channels offer an interesting orthogonal probe to study the existing B anomalies in semitauonic transitions and are accessible with the Belle II experiment. The predictions are based on combining existing light-cone sum-rule calculations for the form factors with measured experimental spectra from the BaBar and Belle collaborations. This allows us to reliably extrapolate the light-lepton form factor predictions to large values of the four-momentum transfer squared, $q^{2}$ , and in turn to derive precise predictions for $R_{ρ}$ and $R_{ω}$ , the ratio of the total decay rates of $B \to ρ τ ν_{τ}$ and $B \to ω τ ν_{τ}$ for $τ$ final states with respect to light leptons in the SM. In addition, we investigate the impact of all four-fermi operators on the semitauonic $q^{2}$ spectra and these ratios.
hep-phPoS(2020)·3 citations
06*
Coulomb-Nuclear Interference:the Latest Modification
Vladimir A. Petrov🇷🇺
We argue that the account of Coulomb-nuclear interference (CNI) in the differential cross-section of elastic $pp$ scattering may be easily treated without introduction of intermediate IR regularization ("photon mass"). We also indicate that the parametrization used earlier misses some terms of the second order in $α$ while it contains a superfluous term of the first order.
hep-phProc.Steklov Inst.Math.(2020)·14 citations
07*
Constraining EDM and MDM lepton dimension five interactions in the electroweak sector
Jonas B. Araujo🇧🇷 · Victor E. Mouchrek-Santos🇧🇷 · Frederico E. P. dos Santos🇧🇷 · Pedro D. S. Silva🇧🇷 · Manoel M. Ferreira Jr🇧🇷
We investigate dimension five Lorentz-violating nonminimal interactions in the electroweak sector, in connection with the possible generation of electric dipole moment (EDM), weak electric dipole moment (WEDM), magnetic dipole moment (MDM) and weak magnetic dipole moment (WMDM) for leptons. These couplings are composed of the physical fields and LV tensors of ranks ranging from 1 to 4. The CPT-odd couplings do no generate EDM\ behavior and do not provide the correct MDM\ signature, while the CPT-even ones yield EDM and MDM\ behavior, being subject to improved constraining. Tau lepton experimental data is used to constrain the WEDM\ and WMDM couplings to the level of $1 0^{- 4} (GeV)^{- 1},$ whereas electron MDM and EDM data is employed to improve constraints to the level of $1 0^{- 17} (GeV)^{- 1}$ and $1 0^{- 11} (GeV)^{- 1},$ respectively.
hep-phhep-thPLB(2020)·1 citation
08*
Reflective scattering at the LHC and two--scale structure of a proton
S.M. Troshin🇷🇺 · N.E. Tyurin🇷🇺
We discuss interpretation of the reflective scattering mode connecting its appearance with a resolution of a two--scale structure of a proton revealed in the DVCS process at Jefferson laboratory and in the differential cross--section of elastic $pp$ --scattering at the LHC at the energy of $s = 13$ TeV.
hep-phEPL(2020)·9 citations
09*
Quark mass effects in two-loop Higgs amplitudes
Charalampos Anastasiou🇨🇭 · Nicolas Deutschmann🇨🇭 · Armin Schweitzer🇨🇭
We provide two two-loop amplitudes relevant for precision Higgs physics. The first is the two-loop amplitude for Higgs boson production through gluon fusion with exact dependence on the top quark mass up to squared order in the dimensional regulator $ϵ$ . The second result we provide is the two-loop amplitude for the decay of a Higgs boson into a pair of massive bottom quarks through the Higgs-to-gluon coupling in the infinite top mass limit. Both amplitudes are computed by finding canonical bases of master integrals, which we evaluate explicitly in terms of harmonic polylogarithms. We obtain the bare, renormalized and IR-subtracted amplitude and provide the results in terms of building blocks suitable to changing renormalization schemes.
hep-phJHEP(2020)·13 citations
10*
A comprehensive analysis of weak transition form factors for doubly heavy baryons in the light front approach
Xiao-Hui Hu🇨🇳 · Run-Hui Li🇨🇳 · Zhi-Peng Xing🇨🇳
The transition form factors for doubly heavy baryons into a spin- $1/2$ or spin- $3/2$ ground-state baryon induced by both the charged current and the flavor changing neutral current are systematically studied within the light-front quark model. In the transition the two spectator quarks have two spin configurations and both are considered in this calculation. We use an updated vertex functions, and inspired by the flavor SU(3) symmetry, we also provide a new approach to derive the flavor-spin factors. With the obtained transition form factors, we perform a phenomenological study of the corresponding semi-leptonic decays of doubly heavy baryons induced by the $c \to d / s ℓ^{+} ν$ , $b \to c / u ℓ^{-} ν ˉ$ and $b \to d / s ℓ^{+} ℓ^{-}$ . Results for partial decay widths, branching ratios and the polarization ratios $Γ_{L} / Γ_{T}$ s are given. We find that most branching ratios for the semi-leptonic decays induced by the $c \to d, s$ transitions are at the order of $1 0^{- 3} \sim 1 0^{- 2}$ , which might be useful for the search of other doubly-heavy baryons. Uncertainties in form factors, the flavor SU(3) symmetry and sources of symmetry breaking effects are discussed. We find that the SU(3) symmetry breaking effects could be sizable in charmed baryon decays while in the bottomed case, the SU(3) symmetry breaking effects are less significant. Our results can be examined at the experimental facilities in the future.
hep-phEPJC(2020)·50 citations
11*
Prospects for New Physics from gauge Left-Right-Colour-Family Grand Unification hypothesis
António P. Morais🇵🇹 · Roman Pasechnik🇸🇪 · Werner Porod🇩🇪
Given the tremendous phenomenological success of the Standard Model (SM) framework, it becomes increasingly important to understand to what extent its specific structure dynamically emerges from unification principles. In this study, we present a novel anomaly-free supersymmetric (SUSY) Grand Unification model based upon gauge trinification $[SU (3)]^{3}$ symmetry and a local $SU (2)_{F} \times U (1)_{F}$ family symmetry, with particle spectra and gauge symmetries inspired by a possible reduction pattern $E_{8} \to E_{6} \times SU (2)_{F} \times U (1)_{F}$ , with subsequent $E_{6} \to [SU (3)]^{3}$ symmetry breaking step. In this framework, higher-dimensional operators of $E_{6}$ induce the threshold corrections in the gauge and Yukawa interactions leading, in particular, to only two distinct Yukawa couplings in the fundamental sector of the resulting $[SU (3)]^{3} \times SU (2)_{F} \times U (1)_{F}$ Lagrangian. Among the appealing features emergent in this framework are the Higgs-matter unification and a unique minimal three Higgs doublet scalar sector at the electroweak scale as well as tree-level hierarchies in the light fermion spectra consistent with those observed in nature. In addition, our framework reveals a variety of prospects for New Physics searches at the LHC and future colliders such as vector-like fermions, as well as rich scalar, gauge and neutrino sectors.
hep-phEPJC(2020)·22 citations
12*
Chiral effective Lagrangian for heavy-light mesons from QCD
Qing-Sen Chen🇨🇳 · Hui-Feng Fu🇨🇳 · Yong-Liang Ma🇨🇳 · Qing Wang🇨🇳
We derive the chiral effective Lagrangian for heavy-light mesons in the heavy quark limit from QCD under proper approximations. The low energy constants in the effective Lagrangian are expressed in terms of the light quark self-energy. With typical forms of the running coupling constant of QCD and the quark self-energy obtained from Dyson-Schwinger equations as well as lattice QCD, we estimate the low energy constants in the model and the strong decay widths. A comparison with data and some discussions of the numerical results are presented.
hep-phnucl-thPRD(2020)·4 citations
13*
On gauge invariance of transverse momentum dependent distributions at small x
Renaud Boussarie🇺🇸 · Yacine Mehtar-Tani🇺🇸
The interplay between the small x limit of QCD amplitudes and QCD factorization at moderate x has been studied extensively in recent years. It was finally shown that semiclassical formulations of small x physics can have the form of an infinite twist framework involving Transverse Momentum Dependent (TMD) distributions in the eikonal limit. In this work, we demonstrate that small x distributions can be formulated in terms of transverse gauge links. This allows in particular for direct and efficient decompositions of observables into subamplitudes involving gauge invariant sub-operators which span parton distributions.
hep-phhep-thnucl-thPRD(2021)·38 citations
14*
The transverse momentum spectrum of low mass Drell-Yan production at next-to-leading order in the parton branching method
A. Bermudez Martinez🇩🇪 · P.L.S. Connor🇩🇪 · D. Dominguez Damiani🇩🇪 · L.I. Estevez Banos🇩🇪 · F. Hautmann🇧🇪 · H. Jung🇩🇪 · J. Lidrych🇩🇪 · A. Lelek🇧🇪 · M. Mendizabal🇩🇪 · M. Schmitz🇩🇪 · S. Taheri Monfared🇩🇪 · Q. Wang🇨🇳 and 3 other authors
It has been observed in the literature that measurements of low-mass Drell-Yan (DY) transverse momentum spectra at low center-of-mass energies $s$ are not well described by perturbative QCD calculations in collinear factorization in the region where transverse momenta are comparable with the DY mass. We examine this issue from the standpoint of the Parton Branching (PB) method, combining next-to-leading-order (NLO) calculations of the hard process with the evolution of transverse momentum dependent (TMD) parton distributions. We compare our predictions with experimental measurements at low DY mass, and find very good agreement.In addition we use the low mass DY measurements at low $s$ to determine the width $q_{s}$ of the intrinsic Gauss distribution of the PB-TMDs at low evolution scales. We find values close to what has earlier been used in applications of PB -TMDs to high-energy processes at the Large Hadron Collider (LHC) and HERA. We find that at low DY mass and low $s$ even in the region of $p_{t} / m_{D Y} \sim 1$ the contribution of multiple soft gluon emissions (included in the PB-TMDs) is essential to describe themeasurements, while at larger masses ( $m_{D Y} \sim m_{Z}$ ) and LHC energies the contribution from soft gluons in the region of $p_{t} / m_{D Y} \sim 1$ is small.
hep-phEPJC(2020)·89 citations
15*
Enhanced pair production in frequency modulated Sauter potential wells
Li Wang🇨🇳 · Binbing Wu🇨🇳 · Lie-Juan Li🇨🇳 · B. S. Xie🇨🇳
Electron-positron pair production in frequency modulated Sauter potential wells is investigated in the framework of the computational quantum field theory. In combined potential wells with a static Sauter potential well and a frequency modulated oscillating one, the modulated amplitude has a large effect on the number of created pairs. The optimal modulation amplitude of frequency at different center frequencies is obtained, which increases the number of electrons at about two times. However, for a single oscillating potential well with frequency modulation, chirp effect is sensitive to the center frequency, and the number of electrons can be enhanced even to four orders of magnitude at a regime of low center frequency. It implies that for a slowly oscillating Sauter potential well, the chirp effect through the frequency modulation is better than adding a static potential well to improve the pair production.
↳ quant-phhep-ph1 citation
16*
Beam energy dependence of net- $Λ$ fluctuations measured by the STAR experiment at RHIC
STAR Collaboration: J. Adam🇺🇸 · L. Adamczyk🇵🇱 · J. R. Adams🇺🇸 · J. K. Adkins🇺🇸 · G. Agakishiev🇷🇺 · M. M. Aggarwal🇮🇳 · Z. Ahammed🇮🇳 · I. Alekseev🇷🇺 · D. M. Anderson🇺🇸 · A. Aparin🇷🇺 · E. C. Aschenauer🇺🇸 · M. U. Ashraf🇨🇳 and 346 other authors
The measurements of particle multiplicity distributions have generated considerable interest in understanding the fluctuations of conserved quantum numbers in the Quantum Chromodynamics (QCD) hadronization regime, in particular near a possible critical point and near the chemical freeze-out. We report the measurement of efficiency and centrality bin width corrected cumulant ratios ( $C_{2} / C_{1}$ , $C_{3} / C_{2}$ ) of net- $Λ$ distributions, in the context of both strangeness and baryon number conservation, as a function of collision energy, centrality and rapidity. The results are for Au + Au collisions at five beam energies ( $s_{N N}$ = 19.6, 27, 39, 62.4 and 200 GeV) recorded with the Solenoidal Tracker at RHIC (STAR). We compare our results to the Poisson and negative binomial (NBD) expectations, as well as to Ultra-relativistic Quantum Molecular Dynamics (UrQMD) and Hadron Resonance Gas (HRG) model predictions. Both NBD and Poisson baselines agree with data within the statistical and systematic uncertainties. The ratios of the measured cumulants show no features of critical fluctuations. The chemical freeze-out temperatures extracted from a recent HRG calculation, which was successfully used to describe the net-proton, net-kaon and net-charge data, indicate $Λ$ freeze-out conditions similar to those of kaons. However, large deviations are found when comparing to temperatures obtained from net-proton fluctuations. The net- $Λ$ cumulants show a weak, but finite, dependence on the rapidity coverage in the acceptance of the detector, which can be attributed to quantum number conservation.
↳ nucl-exhep-exhep-phnucl-thPRC(2020)·32 citations
17*
On a curious bias arising when the $χ^{2} / ν$ scaling prescription is first applied to a sub-sample of the individual results
Giulio D'Agostini🇮🇹
As it is well known, the standard deviation of a weighted average depends only on the individual standard deviations, but not on the dispersion of the values around the mean. This property leads sometimes to the embarrassing situation in which the combined result 'looks' somehow at odds with the individual ones. A practical way to cure the problem is to enlarge the resulting standard deviation by the $χ^{2} / ν$ scaling, a prescription employed with arbitrary criteria on when to apply it and which individual results to use in the combination. But the `apparent' discrepancy between the combined result and the individual ones often remains. Moreover this rule does not affect the resulting `best value', even if the pattern of the individual results is highly skewed. In addition to these reasons of dissatisfaction, shared by many practitioners, the method causes another issue, recently noted on the published measurements of the charged kaon mass. It happens in fact that, if the prescription is applied twice, i.e. first to a sub-sample of the individual results and subsequently to the entire sample, then a bias on the result of the overall combination is introduced. The reason is that the prescription does not guaranty statistical sufficiency, whose importance is reminded in this script, written with a didactic spirit, with some historical notes and with a language to which most physicists are accustomed. The conclusion contains general remarks on the effective presentation of the experimental findings and a pertinent puzzle is proposed in the Appendix.
↳ physics.data-anhep-phmath.HO8 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.