HEP Phenomenology·hep-ph
19 papers—6 primary·13 cross-listed·reconstructed*
Witold Skiba🇺🇸 · Qing Xia🇺🇸
We compute bounds on coefficients of effective operators in the Standard Model that can be inferred from observations of neutrino scattering by the COHERENT experiment. While many operators are bound extremely well by past experiments the full future data set from COHERENT will provide modest improvements for some operators.
Glòria Montaña🇪🇸 · Olaf Kaczmarek🇩🇪 · Laura Tolos🇩🇪 · Angels Ramos🇪🇸
The open-charm Euclidean correlators have been computed for the first time using the thermal spectral functions extracted from a finite-temperature self-consistent unitarized approach based on a chiral effective field theory that implements heavy-quark spin symmetry. The inclusion of the full-energy dependent open-charm spectral functions in the calculation of the Euclidean correlators leads to a similar behaviour as the one obtained in lattice QCD for temperatures well below the transition deconfinement temperature. The discrepancies at temperatures close or above the transition deconfinement temperature could indicate that higher-energy states, that are not present in the open-charm spectral functions, become relevant for a quantitative description of the lattice QCD correlators at those temperatures. In fact, we find that the inclusion of a continuum of scattering states improves the comparison at small Euclidean times, whereas differences still arise for large times.
K.S. Babu🇺🇸 · Shaikh Saad🇺🇸
The clockwork mechanism, which can naturally explain the origin of small numbers, is implemented in grand unified theories to address the origin of hierarchies in fermion masses and mixings. We show that a minimal Yukawa sector involving a and of Higgs bosons, extended with two clockwork chains consisting of vector-like fermions, can explain the hierarchical patterns with all the Yukawa couplings being of order one. Emergence of a realistic mass spectrum does not require any symmetry that distinguishes the three generations. We develop clockwork-extended GUTs both in the context of SUSY and non-SUSY frameworks. Implementation of the mechanism in non-SUSY scenario assumes a Peccei-Quinn symmetry realized at an intermediate scale, with the clockwork sector carrying non-trivial charges, which solves the strong CP problem and provides axion as a dark matter candidate.
Sergei Gninenko🇷🇺 · Dmitry Gorbunov🇷🇺
The recent confirmation by FNAL of the muon anomaly gives strong evidence for the possible existence of new physics beyond the Standard Model in the muon sector. Thus it is worthy to revisit the existing experimental constraints on models suggesting theoretically consistent explanations of the anomaly. In this work, we point out that accounting for the loss of coherence between the wave packets(mass states) of solar neutrinos is important for setting limits on any model with new flavor-sensitive couplings in the neutrino sector. By taking into account this effect and considering more accurately the experimental constraints from the BOREXINO measurement of the Be solar neutrino interaction rate we corrected the limits previously placed on the coupling of the light to - current in the parameter space relevant to the muon .
Masahiro Ibe🇯🇵 · Shin Kobayashi🇯🇵 · Yuhei Nakayama🇯🇵 · Satoshi Shirai🇯🇵
Recently, the XENON1T collaboration reported an excess in the electron recoil energy spectrum. One of the simplest new physics interpretation is a new neutrino-electron interaction mediated by a light vector particle. However, for the parameter region favored by this excess, the constraints from the stellar cooling are severe. Still, there are astrophysical uncertainties on those constraints. In this paper, we discuss the constraint on the light mediator from the effective number of neutrino Neff in the CMB era, which provides an independent constraint. We show that Neff is significantly enhanced and exceeds the current constraint in the parameter region favored for the XENON1T excess. As a result, the interpretation by a light mediator heavier than about 1 eV is excluded by the Neff constraint.
Bhaskar Dutta🇺🇸 · Sumit Ghosh🇺🇸 · Jason Kumar🇺🇸
We consider strategies for using new datasets to probe scenarios in which light right-handed SM fermions couple to a new gauge group, . This scenario provides a natural explanation for the light flavor sector scale, and a motivation for sub-GeV dark matter. There is parameter space which is currently allowed, but we find that much of it can be probed with future experiments. In particular, cosmological and astrophysical observations, neutrino experiments and experiments which search for displaced visible decay or invisible decay can all play a role. Still, there is a small region of parameter space which even these upcoming experiments will not be able to probe. This model can explain the observed 2.4-3 excess of events at the COHERENT experiment in the parameter space allowed by current laboratory experiments, but the ongoing/upcoming laboratory experiments will decisively probe this possibility.
Marc P. Bellon🇫🇷 · Enrico I. Russo🇫🇷
We develop a system of equations for the propagators and three point functions of the quantum field theory in six dimensions. Inspired from a refinement by Ward on the Schwinger--Dyson equations, the main characteristics of this system are to be formulated purely in terms of renormalized quantities and to give solutions satisfying renormalisation group equations. These properties were difficult to get together, due to the overlapping divergences in the propagator. The renormalisation group equations are an integral part of any efficient resolution scheme of this system and will be instrumental in the study of the resurgent properties of the solutions. It is our belief that this method can be generalized to the case of gauge fields, shedding some light on their quantum properties.
S. Diehl🇺🇸 · K. Joo🇺🇸 · A. Kim🇺🇸 · H. Avakian🇺🇸 · P. Kroll🇩🇪 · K. Park🇰🇷 · D. Riser🇺🇸 · K. Semenov-Tian-Shansky🇷🇺 · K. Tezgin🇺🇸 · K.P. Adhikari🇺🇸 · S. Adhikari🇺🇸 · M.J. Amaryan🇺🇸 and 126 other authors
We have measured beam-spin asymmetries to extract the moment from the hard exclusive reaction above the resonance region, for the first time with nearly full coverage from forward to backward angles in the center-of-mass. The moment has been measured up to 6.6 GeV in , covering the kinematic regimes of Generalized Parton Distributions (GPD) and baryon-to-meson Transition Distribution Amplitudes (TDA) at the same time. The experimental results in very forward kinematics demonstrate the sensitivity to chiral-odd and chiral-even GPDs. In very backward kinematics where the TDA framework is applicable, we found to be negative, while a sign change was observed near 90 in the center-of-mass. The unique results presented in this paper will provide critical constraints to establish reaction mechanisms that can help to further develop the GPD and TDA frameworks.
Punnathat Thaprasop🇹🇭 · Kai Zhou🇩🇪 · Jan Steinheimer🇩🇪 · Christoph Herold🇹🇭
We present different methods of unsupervised learning which can be used for outlier detection in high energy nuclear collisions. The UrQMD model is used to generate the bulk background of events as well as different variants of outlier events which may result from misidentified centrality or detector malfunctions. The methods presented here can be generalized to different and novel physics effects. To detect the outliers, dimensional reduction algorithms are implemented, specifically the Principle Component Analysis (PCA) and Autoencoders (AEN). We find that mainly the reconstruction error is a good measure to distinguish outliers from background. The performance of the algorithms is compared using a ROC curve. It is shown that the number of reduced (encoded) dimensions to describe a single event contributes significantly to the performance of the outlier detection task. We find that the model which is best suited to separate outlier events requires a good performance in reconstructing events and at the same time a small number of parameters.
Zhi-Tao Lu🇨🇳 · Han-Yu Jiang🇨🇳 · Jun He🇨🇳
Recently, a hint for dibaryon was observed at WASA-AT-COSY with a mass about MeV below the threshold. It has a relatively small binding energy compared with the and a width close to the width of the baryon, which suggests that it may be a dibaryon in a molecular state picture. In this work, we study the possible -wave molecular states from the interaction within the quasipotential Bethe-Salpeter equation approach. The interaction is described by exchanging , , and mesons. With reasonable parameters, a bound state can be produced from the interaction. The results also suggest that there may exist two more possible and states with smaller binding energies. The exchange is found to play the most important role to bind two baryons to form the molecular states. An experimental search for possible and states will be helpful for understanding the hint of the dibaryon .
Yoshimasa Hidaka🇯🇵 · Yuji Hirono🇰🇷 · Ryo Yokokura🇯🇵
We discuss the counting of Nambu-Goldstone (NG) modes associated with the spontaneous breaking of higher-form global symmetries. Effective field theories of NG modes are developed based on symmetry breaking patterns, using a generalized coset construction for higher-form symmetries. We derive a formula of the number of gapless NG modes, which involves expectation values of the commutators of conserved charges, possibly of different degrees.
José Lopes🇵🇹 · Thomas Lacroix🇪🇸 · Ilídio Lopes🇵🇹
Dark matter (DM) capture in stars offers a rich phenomenology that makes it possible to probe a wide variety of particle DM scenarios in diverse astrophysical environments. In spite of decades of improvements to refine predictions of capture-related observables and better quantify astrophysical and particle-physics uncertainties, the actual impact of the Galactic phase-space distribution function of DM has been overlooked. In this work, we tackle this problem by making use of self-consistent equilibrium phase-space models based on the Eddington inversion formalism and an extension of this method to a DM halo with some degree of anisotropy in velocity space. We demonstrate that incorrectly accounting for the variation of the DM velocity distribution with position in the Galaxy leads to a systematic error between a factor two and two orders of magnitude, depending in particular on the target star, the DM candidate mass and the type of interaction involved. Moreover, we show that underlying phase-space properties, such as the anisotropy of the velocity tensor, actually play an important part -- previously disregarded -- and can have a sizable impact on predictions of capture rates and subsequent observables. We argue that Eddington-like methods, which self-consistently account for kinematic constraints on the components of the Galaxy, actually provide a reliable next-to-minimal approach to narrow down uncertainties from phase-space modeling on predictions of observables related to DM capture in stars.
Candost Akkaya🇺🇸 · Alex Kovner🇺🇸
We calculate the entanglement entropy of a slab of finite width in the pure Maxwell theory. We find that a large part of entropy is contributed by the entanglement of a mode, nonlocal in terms of the transverse magnetic field degrees of freedom. Even though the entangled mode is nonlocal, its contribution to the entropy is local in the sense that the entropy of a slab of a finite thickness is equal to the entropy of the boundary plus a correction exponential in thickness of the slab.
Zhouyou Fan🇺🇸 · Rui Zhang🇺🇸 · Huey-Wen Lin🇺🇸
The parton distribution functions (PDFs) provide process-independent information about the quarks and gluons inside hadrons. Although the gluon PDF can be obtained from a global fit to experimental data, it is not constrained well in the large- region. Theoretical gluon-PDF studies are much fewer than those of the quark PDFs. In this work, we present the first lattice-QCD results that access the -dependence of the gluon unpolarized PDF of the nucleon. The lattice calculation is carried out with nucleon momenta up to 2.16 GeV, lattice spacing fm, with valence pion masses of 310 and 690 MeV. We use reduced Ioffe-time distributions to cancel the renormalization and implement a one-loop perturbative pseudo-PDF matching to the lightcone distribution. Our matrix element results in coordinate space are consistent with those obtained from the global PDF fits of CT18 NNLO and NNPDF3.1 NNLO. Our fitted gluon PDF extrapolated to the physical pion mass gives consistent results in the region.
The Cherenkov Telescope Array Consortium: A. Acharyya · R. Adam · C. Adams · I. Agudo · A. Aguirre-Santaella · R. Alfaro · J. Alfaro · C. Alispach · R. Aloisio · R. Alves Batista · L. Amati · G. Ambrosi and 438 other authors
We provide an updated assessment of the power of the Cherenkov Telescope Array (CTA) to search for thermally produced dark matter at the TeV scale, via the associated gamma-ray signal from pair-annihilating dark matter particles in the region around the Galactic centre. We find that CTA will open a new window of discovery potential, significantly extending the range of robustly testable models given a standard cuspy profile of the dark matter density distribution. Importantly, even for a cored profile, the projected sensitivity of CTA will be sufficient to probe various well-motivated models of thermally produced dark matter at the TeV scale. This is due to CTA's unprecedented sensitivity, angular and energy resolutions, and the planned observational strategy. The survey of the inner Galaxy will cover a much larger region than corresponding previous observational campaigns with imaging atmospheric Cherenkov telescopes. CTA will map with unprecedented precision the large-scale diffuse emission in high-energy gamma rays, constituting a background for dark matter searches for which we adopt state-of-the-art models based on current data. Throughout our analysis, we use up-to-date event reconstruction Monte Carlo tools developed by the CTA consortium, and pay special attention to quantifying the level of instrumental systematic uncertainties, as well as background template systematic errors, required to probe thermally produced dark matter at these energies. "Full likelihood tables complementing our analysis are provided here [ https://doi.org/10.5281/zenodo.4057987 ]"
Mikhail Shaposhnikov🇨🇭 · Andrey Shkerin🇨🇭 · Inar Timiryasov🇨🇭 · Sebastian Zell🇨🇭
We study gravity coupled to scalar and fermion fields in the Einstein-Cartan framework. We discuss the most general form of the action that contains terms of mass dimension not bigger than four, leaving out only contributions quadratic in curvature. By resolving the theory explicitly for torsion, we arrive at an equivalent metric theory containing additional six-dimensional operators. This lays the groundwork for cosmological studies of the theory. We also perform the same analysis for a no-scale scenario in which the Planck mass is eliminated at the cost of adding an extra scalar degree of freedom. Finally, we outline phenomenological implications of the resulting theories, in particular to inflation and dark matter production.
Tyler D. Blanton🇺🇸 · Stephen R. Sharpe🇺🇸
We present a simplified derivation of the relativistic three-particle quantization condition for identical, spinless particles described by a generic relativistic field theory satisfying a symmetry. The simplification is afforded by using a three-particle quasilocal K matrix that is not fully symmetrized, , and makes extensive use of time-ordered perturbation theory (TOPT). We obtain a new form of the quantization condition. This new form can then be related algebraically to the standard quantization condition, which depends on a fully symmetric three-particle K matrix, . The new derivation is fully explicit, allowing, for example, a closed-form expression for to be given in terms of TOPT amplitudes. The new form of the quantization condition is similar in structure to that obtained in the "finite-volume unitarity" approach, and in a companion paper we make this connection concrete. Our simplified approach should also allow a more straightforward generalization of the quantization condition to nondegenerate particles, and perhaps also to more than three particles.
Tyler D. Blanton🇺🇸 · Stephen R. Sharpe🇺🇸
We show that a recently derived alternative form of the relativistic three-particle quantization condition for identical particles can be rewritten in terms of the R matrix introduced to give a unitary representation of the infinite-volume three-particle scattering amplitude. Combined with earlier work, this shows the equivalence of the relativistic effective field theory approach of Hansen and Sharpe (Refs.[1,2]) and the "finite-volume unitarity" approach of Mai and Döring (Refs.[3,4]). It also provides a generalization of the latter approach to arbitrary angular momenta of two-particle subsystems.
Mathias Garny🇩🇪 · Petter Taule🇩🇪
Loop corrections to the power spectrum are frequently computed using approximate non-linear kernels adopted from an Einstein de-Sitter (EdS) cosmology. We present an algorithm that allows us to take the full time- and scale-dependence of the underlying fluid dynamics into account, and apply it to assess the impact of neutrino free-streaming on the 1- and 2-loop matter power spectrum. Neutrino perturbations are described by a hybrid Boltzmann/two-fluid model, that we show to agree with the CLASS Boltzmann solution at the linear level when using an appropriate effective neutrino sound velocity. We then use this scheme at 1- and 2-loop to perform a precision comparison of the matter power spectrum with simplified treatments of massive neutrinos. For a commonly adopted scheme using cold dark matter+baryon perturbations and EdS kernels to compute non-linear corrections, we find deviations above 1% for k > 0.15 h/Mpc at z=0, and sub-percent agreement on weakly non-linear scales at z=0.5. We also demonstrate the impact of the EdS approximation on the 2-loop power spectrum for massless neutrinos.
* 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.