HEP Phenomenology·hep-ph

Tue·Mar 9, 2021Tuesday·March 9, 2021

35 papers—22 primary·13 cross-listed·reconstructed*

01*
Unsupervised Event Classification with Graphs on Classical and Photonic Quantum Computers
Andrew Blance🇬🇧 · Michael Spannowsky🇬🇧
Photonic Quantum Computers provides several benefits over the discrete qubit-based paradigm of quantum computing. By using the power of continuous-variable computing we build an anomaly detection model to use on searches for New Physics. Our model uses Gaussian Boson Sampling, a $#$ P-hard problem and thus not efficiently accessible to classical devices. This is used to create feature vectors from graph data, a natural format for representing data of high-energy collision events. A simple K-means clustering algorithm is used to provide a baseline method of classification. We then present a novel method of anomaly detection, combining the use of Gaussian Boson Sampling and a quantum extension to K-means known as Q-means. This is found to give equivalent results compared to the classical clustering version while also reducing the $O$ complexity, with respect to the sample's feature-vector length, from $O (N)$ to $O (\mbox l o g (N))$ . Due to the speed of the sampling algorithm and the feasibility of near-term photonic quantum devices, anomaly detection at the trigger level can become practical in future LHC runs.
hep-phhep-exphysics.data-anquant-phJHEP(2020)·54 citations
02*
Distribution amplitudes of light diquarks
Ya Lu🇨🇳 · Daniele Binosi🇮🇹 · Minghui Ding🇮🇹 · Craig D. Roberts🇨🇳 · Hui-Yu Xing🇨🇳 · Chang Xu🇨🇳
Accumulating evidence indicates that soft quark+quark (diquark) correlations play an important role in the structure and interactions of hadrons constituted from three or more valence-quarks; so, it is worth developing insights into diquark structure. Using a leading-order truncation of those equations needed to solve continuum two-valence-body bound-state problems, the leading-twist two-parton distribution amplitudes (DAs) of light-quark scalar and pseudovector diquarks are calculated. The diquark DAs are narrower and taller than the asymptotic profile that characterises mesons. Consequently, the valence quasiparticles in a diquark are less likely to carry a large light-front fraction of the system's total momentum than those in a meson. These features may both influence the form of baryon DAs and be transmitted to diquark distribution functions (DFs), in which case their impact will be felt, e.g. in the proton's $u$ and $d$ valence-quark DFs.
hep-phhep-exhep-latnucl-ex+1EPJA(2021)·16 citations
03*
Universal lepton universality violation in exclusive processes
Lin Dai🇮🇱 · Chul Kim🇰🇷 · Adam K. Leibovich🇺🇸
In high energy exclusive processes involving leptons, QED corrections can be sensitive to infrared scales like the lepton mass and the soft photon energy cut, resulting in large logarithms that need to be resummed to all order in $α$ . When considering the ratio of the exclusive processes between two different lepton flavors, the ratio $R$ can be expressed in terms of factorized functions in the decoupled leptonic sectors. While some of the functional terms cancel, there remain the large logarithms due to the lepton mass difference and the energy cut. This factorization process can be universally applied to the exclusive processes such as $Z \to l^{+} l^{-}$ and $B^{-} \to l^{-} ν ˉ_{l}$ , where the resummed result in the ratio gives significant deviations from the naive expectation from lepton universality.
hep-phPRD(2022)·2 citations
04*
The Asymmetry of Antimatter in the Proton
J. Dove🇺🇸 · B. Kerns🇺🇸 · R. E. McClellan🇺🇸 · S. Miyasaka🇯🇵 · D. H. Morton🇺🇸 · K. Nagai🇯🇵 · S. Prasad🇮🇳 · F. Sanftl🇯🇵 · M. B. C. Scott🇺🇸 · A. S. Tadepalli🇺🇸 · C. A. Aidala🇺🇸 · J. Arrington🇺🇸 and 55 other authors
The fundamental building blocks of the proton, quarks and gluons, have been known for decades. However, we still have an incomplete theoretical and experimental understanding of how these particles and their dynamics give rise to the quantum bound state of the proton and its physical properties, such as for example its spin. The two up and the single down quarks that comprise the proton in the simplest picture account only for a few percent of the proton mass, the bulk of which is in the form of quark kinetic and potential energy and gluon energy from the strong force. An essential feature of this force, as described by quantum chromodynamics, is its ability to create matter-antimatter quark pairs inside the proton that exist only for a very short time. Their fleeting existence makes the antimatter quarks within protons difficult to study, but their existence is discernible in reactions where a matter-antimatter quark pair annihilates. In this picture of quark-antiquark creation by the strong force, the probability distributions as a function of momentum for the presence of up and down antimatter quarks should be nearly identical, since their masses are quite similar and small compared to the mass of the proton. In the present manuscript, we show evidence from muon pair production measurements that these distributions are significantly different, with more abundant down antimatter quarks than up antimatter quarks over a wide range of momentum. These results revive interest in several proposed mechanisms as the origin of this antimatter asymmetry in the proton that had been disfavored by the previous results and point to the future measurements that can distinguish between these mechanisms.
hep-phhep-exnucl-exNature(2021)·123 citations
05*
Hard gluon evolution in warming medium
F. G. Ben🇧🇷 · M. V. T. Machado🇧🇷
We describe the energy distribution of hard gluons travelling through a dense quark-gluon plasma whose temperature increases linearly with time, within a probabilistic perturbative approach. The results were applied to the thermalization problem in heavy ion collisions, in the third stage of the bottom-up picture, to estimate the initial time for the third stage of the bottom-up scenario. We then look at the entropy density and average temperature of the soft thermal bath, as the system approaches (local) thermal equilibrium.
hep-phEPJC(2022)·1 citation
06*
Probing new physics in class-I $B$ -meson decays into heavy-light final states
Fang-Min Cai🇨🇳 · Wei-Jun Deng🇨🇳 · Xin-Qiang Li🇨🇳 · Ya-Dong Yang🇨🇳
With updated experimental data and improved theoretical calculations, several significant deviations are being observed between the Standard Model predictions and the experimental measurements of the branching ratios of $B ˉ_{(s)}^{0} \to D_{(s)}^{(*) +} L^{-}$ decays, where $L$ is a light meson from the set ${π, ρ, K^{(*)}}$ . Especially for the two channels $B ˉ^{0} \to D^{+} K^{-}$ and $B ˉ_{s}^{0} \to D_{s}^{+} π^{-}$ , both of which are free of the weak annihilation contribution, the deviations observed can even reach 4-5 $σ$ . Here we exploit possible new-physics effects in these class-I non-leptonic $B$ -meson decays within the framework of QCD factorization. Firstly, we perform a model-independent analysis of the effects from twenty linearly independent four-quark operators that can contribute, either directly or through operator mixing, to the quark-level $b \to c u ˉ d (s)$ transitions. It is found that, under the combined constraints from the current experimental data, the deviations observed could be well explained at the $1 σ$ level by the new-physics four-quark operators with $γ^{μ} (1 - γ_{5}) \otimes γ_{μ} (1 - γ_{5})$ structure, and also at the $2 σ$ level by the operators with $(1 + γ_{5}) \otimes (1 - γ_{5})$ and $(1 + γ_{5}) \otimes (1 + γ_{5})$ structures. However, the new-physics four-quark operators with other Dirac structures fail to provide a consistent interpretation, even at the $2 σ$ level. Then, as two specific examples of model-dependent considerations, we discuss the case where the new-physics four-quark operators are generated by either a colorless charged gauge boson or a colorless charged scalar, with their masses fixed both at the $1$ ~TeV. Constraints on the effective coefficients describing the couplings of these mediators to the relevant quarks are obtained by fitting to the current experimental data.
hep-phhep-exJHEP(2021)·53 citations
07*
Assignments of the $X (4140)$ , $X (4500)$ , $X (4630)$ and $X (4685)$ based on the QCD sum rules
Zhi-Gang Wang🇨🇳
In this article, we take into account our previous calculations based on the QCD sum rules, and tentatively assign the $X (4630)$ as the $D_{s}^{*} D ˉ_{s 1} - D_{s 1} D ˉ_{s}^{*}$ tetraquark molecular state or $[cs]_{P} [c ˉ s ˉ]_{A} + [cs]_{A} [c ˉ s ˉ]_{P}$ tetraquark state with the $J^{P C} = 1^{-+}$ , and assign the $X (3915)$ and $X (4500)$ as the 1S and 2S $[cs]_{A} [c ˉ s ˉ]_{A}$ tetraquark states respectively with the $J^{P C} = 0^{++}$ . Then we extend our previous works to investigate the LHCb's new tetraquark candidate $X (4685)$ as the first radial excited state of the $X (4140)$ with the QCD sum rules, and obtain the mass $M_{X} = 4.70 \pm 0.12 GeV$ , which is in very good agreement with the experimental value $4684 \pm 7_{- 16}^{+ 13} MeV$ . Furthermore, we investigate the two-meson scattering state contributions in details, and observe that the two-meson scattering states alone cannot saturate the QCD sum rules, the contributions of the tetraquark states play an un-substitutable role, we can saturate the QCD sum rules with or without the two-meson scattering states.
hep-phAdv.High Energy Phys.(2021)·38 citations
08*
On the light front surfaces in the phase space of hadrons in heavy-ion collisions
Rahul Ramachandran Nair🇵🇱
Surfaces corresponding to the constant values of the light front variable forms paraboloids in the phase space of the inclusively produced hadrons in heavy-ion collisions. In this paper, it is demonstrated with the simulated Au-Au collisions at $s = 200$ GeV using the UrQMD event generator that the paraboloidal surface defined by a certain constant value of the light front variable divides the particles in the phase space into two groups such that the distributions of the square of the transverse momentum, the polar angle and the light front variable of particles belonging to one among them can be described with the Boltzmann distribution parameterised by the mass-dependent temperature.
hep-phnucl-th1 citation
09*
Two-loop leading-colour QCD helicity amplitudes for two-photon plus jet production at the LHC
Herschel A. Chawdhry🇬🇧 · Michal Czakon🇩🇪 · Alexander Mitov🇬🇧 · Rene Poncelet🇬🇧
We calculate the complete set of two-loop leading-colour QCD helicity amplitudes for $γ γ j$ -production at hadron colliders. Our results are presented in a compact, fully-analytical form.
hep-phhep-thJHEP(2021)·69 citations
10*
Anomalous dimensions from Yukawa couplings in SMNEFT: four-fermion operators
Alakabha Datta🇺🇸 · Jacky Kumar🇨🇦 · Hongkai Liu🇺🇸 · Danny Marfatia🇺🇸
The Standard Model Neutrino Effective Field Theory (SMNEFT) is the Standard Model Effective Field Theory (SMEFT) augmented with right-handed neutrinos. Building on our previous work, arXiv:2010.12109, we calculate the Yukawa coupling contributions to the one-loop anomalous dimension matrix for the 11 dimension-six four-fermion SMNEFT operators. We also present the new contributions to the anomalous dimension matrix for the 14 four-fermion SMEFT operators that mix with the SMNEFT operators through the Yukawa couplings of the right-handed neutrinos.
hep-phJHEP(2021)·23 citations
11*
Fingerprinting the presence of extra scalars in the $h \to V f f^{'}$ forward-backward asymmetry
Victor Ilisie🇪🇸
In this work we analyse the forward-backward asymmetry of the $h \to V f f^{'}$ decay in the Aligned two-Higgs Doublet Model. The Standard Model prediction for this asymmetry for $V = W$ is small, as it suffers from Yukawa suppression and is absent for $V = Z$ . This does not necessarily have to hold true in the Aligned model where these contributions can in principle be re-enhanced through the independent alignment factors $ς_{f}$ . In this analysis we conclude that, due to the additional contributions corresponding to the Aligned two-Higgs Doublet Model together with extra sources of CP-violation for the $V = Z$ channel, the Standard Model predictions can be significantly modified in a great region of the parameter space. These deviations, that could be potentially measured at the High Luminosity LHC or future Higgs factories, would be a clear signal of new physics, and would shed new light on the possible extensions of the Standard Model and new sources of CP-violation.
hep-phhep-thJHEP(2021)·1 citation
12*
Gravitational contributions to the electron $g$ -factor
Andrew G. Cohen🇨🇳 · David B. Kaplan🇺🇸
In a previous paper, the authors with Ann Nelson proposed that the UV and IR applicability of effective quantum field theories should be constrained by requiring that strong gravitational effects are nowhere encountered in a theory's domain of validity [Phys. Rev. Lett. 82, 4971 (1999)]. The constraint was proposed to delineate the boundary beyond which conventional quantum field theory, viewed as an effective theory excluding quantum gravitational effects, might be expected to break down. In this Letter we revisit this idea and show that quantum gravitational effects could lead to a deviation of size $(α /2 π) m_{e} / M_{p}$ from the Standard Model calculation for the electron magnetic moment. This is the same size as QED and hadronic uncertainties in the theory of $a_{e}$ , and a little more than one order of magnitude smaller than both the dominant uncertainty in its Standard Model value arising from the accuracy with which $α$ is measured, as well as the experimental uncertainty in measurement of $a_{e}$ .
hep-phgr-qchep-exhep-th+124 citations
13*
Looking for Lorentz invariance violation (LIV) in the latest long baseline accelerator neutrino oscillation data
Ushak Rahaman🇿🇦
In this paper, we have analysed the latest data from NO $ν$ A and T2K with the Lorentz invariance violation along with the standard oscillation hypothesis. We have found that the NO $ν$ A data cannot distinguish between the two hypotheses at $1 σ$ confidence level. T2K data and the combined data analysis excluded standard oscillation at $1 σ$ . All three cases do not have any hierarchy sensitivity when analysed with LIV. There is a mild tension between the two experiments, when analysed with LIV, as $θ_{23}$ at \nova best-fit is at higher octant but the same for T2K is at lower octant. NO $ν$ A has a new degeneracy over $sin^{2} θ_{23}$ value, when analysed with LIV.
hep-phhep-exhep-thEPJC(2021)·29 citations
14*
Discovery of higher order QED effect for the vacuum pair production
Wangmei Zha🇨🇳 · Zebo Tang🇨🇳
The higher order quantum electrodynamics (QED) effect for vacuum pair production has been searched without success since 1954. In this paper, we show that the lowest order QED calculations for lepton pair vacuum production in heavy-ion collisions are about 20 $%$ higher than the combined world-wide data with a seven sigma-level of significance and the corresponding higher order QED results are consistent with data. We claim the discovery of higher order effect for the QED pair production, which settles the dust of previous debates for several decades. The verification of higher order QED effect is a fundamental scientific problem, which is an important milestone towards the nonperturbative and nonlinear regime of QED vacuum.
hep-phJHEP(2021)·27 citations
15*
Correlation of the hidden-charm molecular tetraquarks and the charmoniumlike structures existing in the $B \to X Y Z + K$
Fu-Lai Wang🇨🇳 · Xin-Dian Yang🇨🇳 · Rui Chen🇨🇳 · Xiang Liu🇨🇳
The molecular assignments to the three $P_{c}$ states and the similar production mechanism between the $Λ_{b} \to P_{c} + K$ and $B \to X Y Z + K$ convince us the $B$ decaying to a charmonium state plus light mesons could be the appropriate production process to search for the charmoniumlike molecular tetraquarks. In this work, we systematically study the interactions between a charmed (charmed-strange) meson and an anti-charmed (anti-charm-strange) meson, which include the $D^{(*)} D ˉ^{(*)}$ , $D ˉ^{(*)} D ˉ_{1}$ , $D^{(*)} D ˉ_{2}^{*}$ , $D_{s}^{(*)} D ˉ_{s}^{(*)}$ , $D_{s}^{(*)} D ˉ_{s 0}^{*}$ , $D_{s}^{(*)} D ˉ_{s 1}^{'}$ , $D_{s}^{(*)} D ˉ_{s 1}$ , $D_{s}^{(*)} D ˉ_{s 2}^{*}$ systems. After adopting the one-boson-exchange effective potentials, our numerical results indicate that, on one hand, there can exist a serial of isoscalar charmoniumlike $D D ˉ$ and $D_{s} D ˉ_{s}$ molecular states, on the other hand, we can fully exclude the charged charmoniumlike states as the isovector charmoniumlike molecules. Meanwhile, we discuss the two-body hidden-charm decay channels for the obtained $D D ˉ$ and $D_{s} D ˉ_{s}$ molecules, especially the $D^{*} D ˉ^{*}$ molecular tetraquarks. By analyzing the experimental data collected from the $B \to X Y Z + K$ and the mass spectrum and two-body hidden-charm decay channels for the obtained $D D ˉ$ and $D_{s} D ˉ_{s}$ molecules, we find several possible hints of the existence of the charmoniumlike molecular tetraquarks, i.e., a peculiar characteristic mass spectrum of the isoscalar $D^{*} D ˉ^{*}$ molecular systems can be applied to identify the charmoniumlike molecule. We look forward to the future experiments like the LHCb, Belle II, and BESIII Collaborations can test our results with more precise experimental data.
hep-phhep-exPRD(2021)·34 citations
16*
Flavor constraints for a Vector-like quark of Nelson-Barr type
A. L. Cherchiglia🇧🇷 · G. De Conto🇧🇷 · C. C. Nishi🇧🇷
The Nelson-Barr (NB) mechanism to solve the strong CP problem assumes CP conservation, arranges vanishing $θ ˉ$ at tree-level and requires vector-like quarks (VLQs) to transmit the CP breaking to the SM. We analyze the flavor constraints coming from the presence of one such down type VLQ of NB type by performing a global fit on the relevant flavor observables. A comparison is made to the case of one generic VLQ. We find that the allowed parameter space for the VLQ Yukawa couplings and the mixing to the SM are confined to a region much smaller than in the generic case, making the NB case falsifiable in principle.
hep-phJHEP(2021)·20 citations
17*
Improved $K_{e 3}$ radiative corrections sharpen the $K_{μ 2}$ -- $K_{l 3}$ discrepancy
Chien-Yeah Seng🇩🇪 · Daniel Galviz🇩🇪 · Mikhail Gorchtein🇩🇪 · Ulf-G. Meißner🇩🇪
The measurements of $V_{u s}$ in leptonic $(K_{μ 2})$ and semileptonic $(K_{l 3})$ kaon decays exhibit a $3 σ$ disagreement, which could originate either from physics beyond the Standard Model or some large unidentified Standard Model systematic effects. Clarifying this issue requires a careful examination of all existing Standard Model inputs. Making use of a newly-proposed computational framework and the most recent lattice QCD results, we perform a comprehensive re-analysis of the electroweak radiative corrections to the $K_{e 3}$ decay rates that achieves an unprecedented level of precision of $1 0^{- 4}$ , which improves the current best results by almost an order of magnitude. No large systematic effects are found, which suggests that the electroweak radiative corrections should be removed from the ``list of culprits'' responsible for the $K_{μ 2}$ -- $K_{l 3}$ discrepancy.
hep-phhep-exhep-latnucl-ex+1JHEP(2021)·40 citations
18*
A feasibility study of the light front analysis of ultrarelativistic nuclear collisions in ALICE at LHC
Rahul Ramachandran Nair🇵🇱
An analysis involving the light front variables is performed over the inclusively produced $π^{\pm}$ , $K^{\pm}$ and $p (p ˉ)$ in the Pb-Pb collisions simulated using the UrQMD event generator at $s = 2.76$ TeV to study the possible formation of a thermalised medium in these collisions. It is demonstrated that there exist surfaces defined by constant values of the light front variable in the phase space of these hadrons which can select a group of thermalised particles. The temperatures are extracted for each species and are compared with those obtained from a similar calculation involving the kinematical and acceptance restrictions which are typically bound to the collider experiments. It is shown that the analysis is feasible to perform with the data collected at the ALICE experiment at LHC. The analysis may be considered as a prototypical study to a similar experimental analysis of the data from the heavy-ion collisions at RHIC and LHC after implementing the necessary corrections and calibrations relevant to the experimental apparatuses.
hep-ph2 citations
19*
Diamagnetic and Paramagnetic Phases in Low-Energy Quantum Chromodynamics
Christoph P. Hofmann🇲🇽
While it is known that the QCD vacuum in a magnetic background exhibits both diamagnetic and paramagnetic characteristics in the low-energy domain, a systematic investigation of the corresponding phases emerging in the pion-dominated regime is still lacking. Here, within two-flavor chiral perturbation theory, taking into account the pion-pion interaction, we analyze the subtle interplay between zero- and finite-temperature portions in the magnetization and magnetic susceptibility. The dependence of the magnetic susceptibility on temperature and magnetic field strength in the paramagnetic and diamagnetic phase is non-monotonic. Our low-energy analysis complements lattice QCD that is currently operating at higher temperatures and stronger magnetic fields.
hep-phhep-lathep-thPLB(2021)·10 citations
20*
Drell-Yan lepton-pair production: $q_{T}$ resummation at N $^{3}$ LL accuracy and fiducial cross sections at N $^{3}$ LO
Stefano Camarda🇨🇭 · Leandro Cieri🇮🇹 · Giancarlo Ferrera🇮🇹
We present high-accuracy QCD predictions for the transverse-momentum ( $q_{T}$ ) distribution and fiducial cross sections of Drell-Yan lepton pairs produced in hadronic collisions. At small value of $q_{T}$ we resum to all perturbative orders the logarithmically enhanced contributions up to next-to-next-to-next-to-leading logarithmic (N $^{3}$ LL) accuracy, including all the next-to-next-to-next-to-leading order (N $^{3}$ LO) (i.e. $O (α_{S}^{3})$ ) terms. Our resummed calculation has been implemented in the public numerical program DYTurbo, which produces fast and precise predictions with the full dependence on the final-state leptons kinematics. We consistently combine our resummed results with the known $O (α_{S}^{3})$ fixed-order predictions at large values of $q_{T}$ thus obtaining full N $^{3}$ LO accuracy also for fiducial cross sections. We show numerical results at LHC energies discussing the reduction of the perturbative uncertainty with respect to lower-order calculations.
hep-phhep-exPRD(2021)·161 citations
21*
Leaks of CP violation in the real two-Higgs doublet model
Duarte Fontes🇵🇹 · Maximilian Löschner🇩🇪 · Jorge C. Romão🇵🇹 · João P. Silva🇵🇹
We discuss the $Z_{2}$ symmetric two Higgs doublet model with a real soft breaking term (real 2HDM). We explain in detail why it is not tenable to assume CP conservation in the scalar sector to keep the dimension two term real, while CP is violated by the dimension four Yukawa couplings. We propose the calculation of the infinite tadpole of the (would-be) pseudoscalar neutral scalar. We construct a simple toy model with the same flaws, where the unrenormalizable infinity is easier to calculate. We then turn our attention to the same tadpole in the real 2HDM. We spearhead this effort focusing on diagrams involving solely bare quantities. This involves hundreds of Feynman three-loop diagrams that could feed the CP violation from the quark into the scalar sector, and is only possible with state of the art automatic computation tools. Remarkably, some intermediate results agree when using three independent derivations, including the peculiar cancellation of the leading pole divergence due to a subtle interplay between masses and the Jarlskog invariant, which we calculate analytically. The calculation is not complete however, since the full two-loop renormalization of the real 2HDM is not yet available in the literature. Still, we argue convincingly that there is an irremovable infinity.
hep-phEPJC(2021)·23 citations
22*
Electroweak-like Baryogenesis with New Chiral Matter
Kohei Fujikura🇯🇵 · Keisuke Harigaya🇺🇸 · Yuichiro Nakai🇨🇳 · Isaac R. Wang🇺🇸
We propose a framework where a phase transition associated with a gauge symmetry breaking that occurs (not far) above the electroweak scale sets a stage for baryogenesis similar to the electroweak baryogenesis in the Standard Model. A concrete realization utilizes the breaking of $S U (2)_{R} \times U (1)_{X} \to U (1)_{Y}$ . New chiral fermions charged under the extended gauge symmetry have nonzero lepton numbers, which makes the $B - L$ symmetry anomalous. The new lepton sector contains a large flavor-dependent CP violation, similar to the Cabibbo-Kobayashi-Maskawa phase, without inducing sizable electric dipole moments of the Standard Model particles. A bubble wall dynamics associated with the first-order phase transition and $S U (2)_{R}$ sphaleron processes generate a lepton asymmetry, which is transferred into a baryon asymmetry via the ordinary electroweak sphaleron process. Unlike the Standard Model electroweak baryogenesis, the new phase transition can be of the strong first order and the new CP violation is not significantly suppressed by Yukawa couplings, so that the observed asymmetry can be produced. The model can be probed by collider searches for new particles and the observation of gravitational waves. One of the new leptons becomes a dark matter candidate. The model can be also embedded into a left-right symmetric theory to solve the strong CP problem.
hep-phastro-ph.COJHEP(2021)·17 citations
23*
Square Peg in a Circular Hole: Choosing the Right Ansatz for Isolated Black Holes in Generic Gravitational Theories
Yiqi Xie🇺🇸 · Jun Zhang🇬🇧 · Hector O. Silva🇩🇪 · Claudia de Rham🇬🇧 · Helvi Witek🇺🇸 · Nicolas Yunes🇺🇸
The metric of a spacetime can be greatly simplified if the spacetime is circular. We prove that in generic effective theories of gravity, the spacetime of a stationary, axisymmetric and asymptotically flat solution must be circular if the solution can be obtained perturbatively from a solution in the general relativity limit. This result applies to a broad class of gravitational theories that include arbitrary scalars and vectors in their light sector, so long as their nonstandard kinetic terms and nonmininal couplings to gravity are treated perturbatively.
↳ gr-qcastro-ph.HEhep-phPRL(2021)·42 citations
24*
New minimal, median, and maximal propagation models for dark matter searches with Galactic cosmic rays
Yoann Génolini🇩🇰 · Mathieu Boudaud🇪🇸 · Marco Cirelli🇫🇷 · Laurent Derome🇫🇷 · Julien Lavalle🇫🇷 · David Maurin🇫🇷 · Pierre Salati🇫🇷 · Nathanael Weinrich🇫🇷
Galactic charged cosmic rays (notably electrons, positrons, antiprotons and light antinuclei) are powerful probes of dark matter annihilation or decay, in particular for candidates heavier than a few MeV or tiny evaporating primordial black holes. Recent measurements by PAMELA, AMS-02, or VOYAGER on positrons and antiprotons already translate into constraints on several models over a large mass range. However, these constraints depend on Galactic transport models, in particular the diffusive halo size, subject to theoretical and statistical uncertainties. We update the so-called MIN-MED-MAX benchmark transport parameters that yield generic minimal, median and maximal dark-matter induced fluxes; this reduces the uncertainties on fluxes by a factor of about 2 for positrons and 6 for antiprotons, with respect to their former version. We also provide handy fitting formulae for the associated predicted secondary antiproton and positron background fluxes. Finally, for more refined analyses, we provide the full details of the model parameters and covariance matrices of uncertainties.
↳ astro-ph.HEhep-phPRD(2021)·49 citations
25*
Baryogenesis, magnetogenesis and the strength of anomalous interactions
Massimo Giovannini🇨🇭
The production of the hypermagnetic gyrotropy is investigated under the assumption that the gauge coupling smoothly evolves during a quasi-de Sitter phase and then flattens out in the radiation epoch by always remaining perturbative. In the plane defined by the strength of the anomalous interactions and by the rate of evolution of the gauge coupling the actual weight of the pseudoscalar interactions turns out to be always rather modest if major deviations from the homogeneity are to be avoided during the inflationary phase. Even if the gauge power spectra are related by duality only in the absence of anomalous contributions, an approximate duality symmetry constrains the late-time form of the hypermagnetic power spectra. Since the hypermagnetic gyrotropy associated with the modes reentering prior to the phase transition must be released into fermions later on, the portions of the parameter space where the obtained baryon asymmetry is close to the observed value are the most relevant for the present ends. For the same range of parameters the magnetic power spectra associated with the modes reentering after symmetry breaking may even be of the order of a few hundredths of a nG over typical length scales comparable with the Mpc prior to the collapse of the protogalaxy.
↳ astro-ph.COgr-qchep-phhep-thEPJC(2021)·9 citations
26*
Leading singularities in Baikov representation and Feynman integrals with uniform transcendental weight
Christoph Dlapa🇩🇪 · Xiaodi Li🇨🇳 · Yang Zhang🇨🇳
We provide a leading singularity analysis protocol in Baikov representation, for the searching of Feynman integrals with uniform transcendental (UT) weight. This approach is powered by the recent developments in rationalizing square roots and syzygy computations, and is particularly suitable for finding UT integrals with multiple mass scales. We demonstrate the power of our approach by determining the UT basis for a two-loop diagram with three external mass scales.
↳ hep-thhep-phJHEP(2021)·56 citations
27*
Azimuthal anisotropy measurement of $ϕ$ mesons in Au+Au collisions at $s_{N N}$ = 27 and 54.4 GeV at STAR
Prabhupada Dixit (for the STAR collaboration)🇮🇳
The elliptic flow coefficient ( $v_{2}$ ) of $ϕ$ mesons at mid-rapidity as a function of transverse momentum ( $p_{T}$ ) is measured for Au+Au collisions at centre of mass energy ( $s_{N N}$ ) 27 and 54.4 GeV. The $v_{2}$ measurement is done using event plane from Time Projection Chamber (TPC, $∣ η ∣$ $<$ 1.0) and Event Plane Detectors (EPD, 2.1 $<$ $∣ η ∣$ $<$ 5.1) for 54.4 and 27 GeV, respectively. A high precision test of the number of constituent quark scaling of $ϕ$ meson $v_{2}$ (by including measurements for other hadrons) has been shown. The results are compared to transport model (AMPT) calculations.
↳ hep-exhep-ph2 citations
28*
A topic review on probing primordial black hole dark matter with scalar induced gravitational waves
Chen Yuan🇨🇳 · Qing-Guo Huang🇨🇳
Primordial black holes (PBHs) are supposed to form from the collapse of over-densed regions generated by large scalar curvature perturbations in the radiation dominated era. Despite decades of various independent observations, the nature of dark matter (DM) remains highly puzzling. Recently, PBH DM have aroused interest since they provide an attracting explanation to the merger events of binary black holes discovered by LIGO/VIRGO and may play an important role on DM. During the formation of PBH, gravitational waves will be sourced by linear scalar perturbations at second-order, known as the scalar-induced gravitational waves (SIGWs), which provides a new way to hunt for PBH DM. This topic review mainly focus on the physics about SIGWs accompanying the formation of PBH DM.
↳ astro-ph.GAgr-qchep-phhep-thiScience(2021)·137 citations
29*
Particle Physics Model Building with Reinforcement Learning
T. R. Harvey🇬🇧 · A. Lukas🇬🇧
In this paper, we apply reinforcement learning to particle physics model building. As an example environment, we use the space of Froggatt-Nielsen type models for quark masses. Using a basic policy-based algorithm we show that neural networks can be successfully trained to construct Froggatt-Nielsen models which are consistent with the observed quark masses and mixing. The trained policy networks lead from random to phenomenologically acceptable models for over 90% of episodes and after an average episode length of about 20 steps. We also show that the networks are capable of finding models proposed in the literature when starting at nearby configurations.
↳ hep-thhep-phJHEP(2021)·44 citations
30*
Experiment Simulation Configurations Approximating DUNE TDR
DUNE Collaboration: B. Abi · R. Acciarri · M. A. Acero · G. Adamov · D. Adams · M. Adinolfi · Z. Ahmad · J. Ahmed · T. Alion · S. Alonso Monsalve · C. Alt · J. Anderson and 961 other authors
The Deep Underground Neutrino Experiment (DUNE) is a next-generation long-baseline neutrino oscillation experiment consisting of a high-power, broadband neutrino beam, a highly capable near detector located on site at Fermilab, in Batavia, Illinois, and a massive liquid argon time projection chamber (LArTPC) far detector located at the 4850L of Sanford Underground Research Facility in Lead, South Dakota. The long-baseline physics sensitivity calculations presented in the DUNE Physics TDR, and in a related physics paper, rely upon simulation of the neutrino beam line, simulation of neutrino interactions in the near and far detectors, fully automated event reconstruction and neutrino classification, and detailed implementation of systematic uncertainties. The purpose of this posting is to provide a simplified summary of the simulations that went into this analysis to the community, in order to facilitate phenomenological studies of long-baseline oscillation at DUNE. Simulated neutrino flux files and a GLoBES configuration describing the far detector reconstruction and selection performance are included as ancillary files to this posting. A simple analysis using these configurations in GLoBES produces sensitivity that is similar, but not identical, to the official DUNE sensitivity. DUNE welcomes those interested in performing phenomenological work as members of the collaboration, but also recognizes the benefit of making these configurations readily available to the wider community.
↳ hep-exhep-ph154 citations
31*
Derivation of the nonlocal collision term in the relativistic Boltzmann equation for massive spin-1/2 particles from quantum field theory
Nora Weickgenannt🇩🇪 · Enrico Speranza🇺🇸 · Xin-li Sheng🇨🇳 · Qun Wang🇨🇳 · Dirk H. Rischke🇩🇪
We derive the Boltzmann equation and the collision kernel for massive spin-1/2 particles, using the Wigner-function formalism and employing an expansion in powers of $ℏ$ . The phase space is enlarged to include a variable related to the spin degrees of freedom. This allows to reduce the transport equations of the independent components of the Wigner function to one scalar equation. To next-to-leading order in $ℏ$ , we find that the collision kernel contains both local and nonlocal terms. We show that off-shell contributions cancel in the Boltzmann equation. Our framework can be used to study spin-polarization phenomena induced by vorticity as recently observed in heavy-ion collisions and in condensed-matter systems.
↳ nucl-thhep-phPRD(2021)·128 citations
32*
Nonlocal Spacetime-Matter
Leonardo Modesto🇨🇳
We propose a nonlocal field theory for gravity in presence of matter consistent with perturbative unitarity, quantum finiteness, and other essential classical properties that we are going to list below. First, the theory exactly reproduces the same tree-level scattering amplitudes of Einstein's gravity coupled to matter insuring no violation of macro-causality. Second, all the exact solutions of the Einstein's theory are also exact solutions of the nonlocal theory. Finally, and most importantly, the linear and nonlinear stability analysis of the exact solutions in nonlocal gravity (with or without matter) is in one to one correspondence with the same analysis in General Relativity. Therefore, all the exact solutions stable in the Einstein's theory are also stable in nonlocal gravity in presence of matter at any perturbative order.
↳ gr-qchep-phhep-th22 citations
33*
No H_0 Assistance from Assisted Quintessence
Vivian I. Sabla🇺🇸 · Robert R. Caldwell🇺🇸
Early dark energy, as a proposed solution to the Hubble tension, faces an additional "why now" problem. Why should dark energy emerge just prior to recombination, billions of years before the onset of cosmic acceleration? Assisted quintessence explains this connection by positing that multiple scaling fields build up over time to drive the present-day cosmic acceleration. In this framework, early dark energy is inevitable. Yet, we show that scaling also leads to the demise of the scenario: the same feature that solves the coincidence problem then spoils a concordance of the Hubble constant inferred from the cosmic microwave background with that from the local distance ladder. The failure of the model offers a novel lesson on the ability of new physics to resolve the Hubble tension.
↳ astro-ph.COgr-qchep-phPRD(2021)·43 citations
34*
The Galactic potential and dark matter density from angular stellar accelerations
Malte Buschmann🇺🇸 · Benjamin R. Safdi🇺🇸 · Katelin Schutz🇨🇦
We present an approach to measure the Milky Way (MW) potential using the angular accelerations of stars in aggregate as measured by astrometric surveys like Gaia. Accelerations directly probe the gradient of the MW potential, as opposed to indirect methods using e.g. stellar velocities. We show that end-of-mission Gaia stellar acceleration data may be used to measure the potential of the MW disk at approximately 3 $σ$ significance and, if recent measurements of the solar acceleration are included, the local dark matter density at ~2 $σ$ significance. Since the significance of detection scales steeply as $t^{5/2}$ for observing time $t$ , future surveys that include angular accelerations in the astrometric solutions may be combined with Gaia to precisely measure the local dark matter density and shape of the density profile.
↳ astro-ph.GAhep-phPRL(2021)·20 citations
35*
Science Requirements and Detector Concepts for the Electron-Ion Collider: EIC Yellow Report
R. Abdul Khalek🇳🇱 · A. Accardi🇺🇸 · J. Adam🇺🇸 · D. Adamiak🇺🇸 · W. Akers🇺🇸 · M. Albaladejo🇺🇸 · A. Al-bataineh🇸🇦 · M. G. Alexeev🇮🇹 · F. Ameli🇮🇹 · P. Antonioli🇮🇹 · N. Armesto🇪🇸 · W. R. Armstrong🇺🇸 and 403 other authors
This report describes the physics case, the resulting detector requirements, and the evolving detector concepts for the experimental program at the Electron-Ion Collider (EIC). The EIC will be a powerful new high-luminosity facility in the United States with the capability to collide high-energy electron beams with high-energy proton and ion beams, providing access to those regions in the nucleon and nuclei where their structure is dominated by gluons. Moreover, polarized beams in the EIC will give unprecedented access to the spatial and spin structure of the proton, neutron, and light ions. The studies leading to this document were commissioned and organized by the EIC User Group with the objective of advancing the state and detail of the physics program and developing detector concepts that meet the emerging requirements in preparation for the realization of the EIC. The effort aims to provide the basis for further development of concepts for experimental equipment best suited for the science needs, including the importance of two complementary detectors and interaction regions. This report consists of three volumes. Volume I is an executive summary of our findings and developed concepts. In Volume II we describe studies of a wide range of physics measurements and the emerging requirements on detector acceptance and performance. Volume III discusses general-purpose detector concepts and the underlying technologies to meet the physics requirements. These considerations will form the basis for a world-class experimental program that aims to increase our understanding of the fundamental structure of all visible matter
↳ physics.ins-dethep-exhep-phnucl-ex+1NPA(2022)·1653 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.