HEP Phenomenology·hep-ph
29 papers—19 primary·10 cross-listed·reconstructed*
Martin Beneke🇩🇪 · Robert Szafron🇨🇭 · Kai Urban🇩🇪
Extending previous work, we calculate the electroweak potentials for all co-annihilation channels of wino dark matter at the one-loop order and obtain the wino relic abundance including the Sommerfeld effect at the next-to-leading order (NLO).
I review some key aspects of capture and possible observable effects of particle dark matter in stars. Focusing on the transport of heat from captured asymmetric dark matter, I outline existing computational methods, and the challenges that must be overcome to continue pushing the field forward.
Alejandro Ayala🇲🇽 · Jorge David Castaño-Yepes🇲🇽 · L. A. Hernández🇲🇽 · Jordi Salinas🇲🇽 · R. Zamora🇨🇱
We study the polarization and dispersion properties of gluons moving within a weakly magnetized background at one-loop order. To this end, we show two alternative derivations of the charged fermion propagator in the weak field expansion and use this expression to compute the lowest order magnetic field correction to the gluon polarization tensor. We explicitly show that, in spite of its cumbersome appearance, the gluon polarization tensor is transverse as required by gauge invariance. We also show that none of the three polarization modes develops a magnetic mass and that gluons propagate along the light cone, non withstanding that Lorentz invariance is lost due to the presence of the magnetic field. By comparing with the expression for the gluon polarization tensor valid to all orders in the magnetic field, the existence of a second solution, corresponding to a finite gluon mass, is shown to be spurious and an artifact of the lowest order approximation in the field strength. We also study the strength of the polarization modes for real gluons. We conclude that, provided the spurious solutions are discarded, the lowest order approximation to the gluon polarization and dispersion properties is good as long as the field strength is small compared to the loop fermion mass.
Rambabu Korrapati🇮🇳 · Jai More🇮🇳 · Ushak Rahaman🇿🇦 · S. Uma Sankar🇮🇳
We study the charged lepton flavour violation in a popular neutrino mass model with discrete symmetry. This symmetry requires the presence of multiple Higgs doublets in the model and it also dictates the flavour violating Yukawa couplings of the additional neutral scalars of the model. Such couplings lead to the decays of the neutral mesons, the top quark and the lepton into charged leptons of different flavours at tree level. The symmetry of the model leads to certain characteristic signatures in these decays. We discuss these signatures and predict the rates for the most favourable charged lepton flavour violating modes.
Manoranjan Dutta🇮🇳 · Subhaditya Bhattacharya🇮🇳 · Purusottam Ghosh🇮🇳 · Narendra Sahu🇮🇳
In a bid to simultaneous explanation of dark matter (DM) and tiny but non-zero masses of left-handed neutrinos, we propose a minimal extension of the Standard Model (SM) by a vector-like fermion doublet and three right handed (RH) singlet neutrinos. The DM arises as a mixture of the neutral component of the fermion doublet and one of the RH neutrinos, both assumed to be odd under an additional symmetry. As a result, the DM emerges to be a dominantly Majorana particle and escapes from -mediated direct search constraints to mark a significant difference from singlet-doublet Dirac DM. The other two even heavy RH neutrinos give rise masses and mixing of light neutrinos via Type-I Seesaw mechanism. The particle content automatically allows us to extend the model by a gauged symmetry, which is anomaly free and brings an additional portal between DM and SM particles. Relic density and direct search allowed parameter space for both the cases are investigated through detailed numerical scan, while collider search strategies are also indicated.
Gino Isidori🇨🇭 · Saad Nabeebaccus🇬🇧 · Roman Zwicky🇬🇧
We present a detailed analysis of QED corrections to decays at the double-differential level. Cancellations of soft and collinear divergences are demonstrated analytically using the phase space slicing method. Whereas soft divergences are found to cancel at the differential level, the cancellation of the hard-collinear logs require, besides photon-inclusiveness, a specific choice of kinematic variables. In particular, hard-collinear logs in the lepton-pair invariant mass distribution (), are sizeable and need to be treated with care when comparing with experiment. Virtual and real amplitudes are evaluated using an effective mesonic Lagrangian. Crucially, we show that going beyond this approximation does not introduce any further infrared sensitive terms. All analytic computations are performed for generic charges and are therefore adaptable to semileptonic decays such as .
Y. Brihaye🇧🇪 · F. Buisseret🇧🇪
The equation of state of SU(3) Yang-Mills theory can be modelled by an effective symmetric potential depending on the temperature and on a scalar field -- the averaged Polyakov loop. Allowing to be dynamical opens the way to the study of spatially localized classical configurations of the Polyakov loop. We first show that spherically symmetric static Q-balls exist in the range , being the deconfinement temperature. Then we argue that Q-holes solutions, if any are unphysical within our framework. Finally we couple the Polyakov-loop Lagrangian to Einstein gravity and show that spherically symmetric static boson stars exist in the same range of temperature. The Q-ball and boson star solutions we find can be interpreted as "bubbles" of deconfined gluonic matter; their mean radius is always smaller than 10 fm.
This talk at the CPT'19 meeting outlines a few recent developments in Lorentz and CPT violation, with particular attention to results obtained by researchers at the Indiana University Center for Spacetime Symmetries.
In this thesis, QCD is studied from three different directions, with one overarching theme: holography. The holographic duality allows certain strongly coupled QFTs to be described in terms of much simpler classical gravity in one dimension more. The first direction from which QCD is studied in this thesis is by examining the effects of an external magnetic field on a particular holographic model of QCD, yielding interesting qualitative insight. The second approach examines how, in the same model, one can describe dense baryonic configurations, providing a new way to study the matter composing neutron stars. Indeed, the equation of state produced in this way is subsequently used to compute several neutron star properties which are observable, or will be in the near future. The last direction contains no holographic computations per se, but does incorporate several qualitative insights from holography into a new heavy ion code called Trajectum. This will in the near future be used to perform a Bayesian analysis, whereby it is hoped that these qualitative insights from holography can be tested on experimental data, to see how well the ideas coming from holography match up with experiment.
Geraint W. Evans🇬🇧 · Andreas Schmitt🇬🇧
Dense quark matter is expected to behave as a type-II superconductor at strong coupling. It was previously shown that if the strange quark mass is neglected, magnetic domain walls in the so-called 2SC phase are the energetically preferred magnetic defects in a certain parameter region. Computing the flux tube profiles and associated free energies within a Ginzburg-Landau approach, we find a cascade of multi-winding flux tubes as "remnants" of the domain wall when is increased. These flux tubes exhibit an unconventional ring-like structure of the magnetic field. We show that flux tubes with winding numbers larger than one survive for values of up to about 20% of the quark chemical potential. This makes them unlikely to play a significant role in compact stars, but they may appear in the QCD phase diagram in the presence of an external magnetic field.
Yan-Ke Chen🇨🇳 · Jia-Jie Han🇨🇳 · Qi-Fang Lü🇨🇳 · Jian-Peng Wang🇨🇳 · Fu-Sheng Yu🇨🇳
The exotic states with the quark flavor of are recently observed in the mass spectrum of in by the LHCb collaboration. To explore the nature of , except for analyzing their masses and decay widths as usually did in literatures, the study of their production mechanism in -meson weak decays would provide another important information. The amplitude of is non-factorizable. We consider the final-state-interaction effects and calculate them via the rescattering mechanism. The measured branching fractions of are revealed. It is manifested by and that the rescattering mechanism can result in the relatively large branching fractions. The similar processes of are also analyzed. The isospins of can be investigated by decays.
Lukas Graf🇩🇪 · Brian Henning🇨🇭 · Xiaochuan Lu🇺🇸 · Tom Melia🇯🇵 · Hitoshi Murayama🇺🇸
We apply Hilbert series techniques to the enumeration of operators in the mesonic QCD chiral Lagrangian. Existing Hilbert series technologies for non-linear realizations are extended to incorporate the external fields. The action of charge conjugation is addressed by folding the Dynkin diagrams, which we detail in an appendix that can be read separately as it has potential broader applications. New results include the enumeration of anomalous operators appearing in the chiral Lagrangian at order , as well as enumeration of -even, -odd, -odd, and -odd terms beginning from order . The method is extendable to very high orders, and we present results up to order . (The title sequence is the number of independent -even -even operators in the mesonic QCD chiral Lagrangian with three light flavors of quarks, at chiral dimensions , , , ...)
Andreas Crivellin🇨🇭 · Fiona Kirk🇨🇭 · Marco Schreck🇧🇷
Lorentz invariance is one of the basic ingredients of quantum field theories and violations of it are stringently constrained experimentally. Therefore, the possibility of Lorentz violation (LV) is usually realized at very high energy scales, resulting in a strong suppression of it (by the new scale) in experiments. The Standard-Model Extension (SME) parameterizes LV in a model-independent way, respecting gauge invariance. This means, e.g., that the neutrino and charged-lepton sectors are linked to each other. Hence, on the one hand, any modification of neutrino properties simultaneously gives rise to effects for charged leptons, which is why the tight limits on flavour-off-diagonal LV for neutrinos imply new bounds on modifications of charged leptons. On the other hand, LV for left-handed charged leptons implies LV for neutrinos. Since LV modifications of the charged-lepton sector are, in general, even more constraining than effects in the flavour-diagonal neutrino sector, we obtain novel tight bounds on LV in the latter. Subsequently, we apply the same approach to an analysis of time-of-flight data for neutrinos (detected by IceCube) and photons from gamma ray bursts where discrepancies have been observed. Our finding is that an explanation of the arrival time difference between neutrino and photon events by dim-5 operators in the neutrino sector would lead to unacceptably large LV effects in the charged-lepton sector.
D. Marzocca (ed.)🇮🇹 · F. Riva (ed.)🇨🇭 · J. Criado🇪🇸 · S. Dawson🇺🇸 · J. de Blas🇮🇹 · B. Henning🇨🇭 · D. Liu🇺🇸 · C. Murphy🇺🇸 · M. Perez-Victoria🇪🇸 · J. Santiago🇪🇸 · L. Vecchi🇨🇭 · Lian-Tao Wang🇺🇸
Effective Field Theories (EFTs) capture effects from heavy dynamics at low energy and represent an essential ingredient in the context of Standard Model (SM) precision tests. This document gathers a number of relevant scenarios for heavy physics beyond the SM and presents explicit expressions for the Wilson coefficients in their low-energy EFT. It includes i) weakly coupled scenarios in which one or a few particles of different spins and quantum numbers interact linearly with the SM and generate EFT effects at tree-level, ii) scenarios where heavy particles interact quadratically whereupon the resulting EFT arises only at loop-level and iii) strongly coupled scenarios where the size of Wilson coefficients is controlled by symmetry arguments. This review aims at motivating experimental EFT studies in which only a subset of all possible EFT interactions is used, as well as facilitating the theoretical interpretation of EFT fits.
Markus Ahlers🇩🇰 · Mauricio Bustamante🇩🇰 · Niels Gustav Nortvig Willesen🇩🇰
We revisit the flavor composition of high-energy astrophysical neutrinos observed at neutrino telescopes. Assuming unitary time evolution of the neutrino flavor states, the flavor composition observable at Earth is related to the initial composition at their sources via oscillation-averaged flavor transitions. In a previous study we derived general bounds on the flavor composition of TeV-PeV astrophysical neutrinos assuming three-flavor unitary mixing. We extend these bounds to the case of active-sterile neutrino mixing. Our bounds are analytical, derived based only on the unitarity of the mixing, and do not require sampling over the values of the unknown active-sterile mixing parameters. These bounds apply to any extended active-sterile neutrino mixing scenario where energy-dependent nonstandard flavor mixing dominates over the standard mixing observed in accelerator, reactor, and atmospheric neutrino oscillations.
We consider light new particles and that carry baryon and lepton numbers. If these particles are lighter than nucleons they lead to exotic decays such as and , not yet fully constrained by dedicated searches. For and masses in the GeV range proton decays are kinematically forbidden but other decays of the forms baryon meson, meson baryon, and baryon anti-lepton involving heavy initial hadrons are allowed. This opens up the possibility to search for apparent baryon number violation not just in underground experiments such as Super-Kamiokande and DUNE but also in decays of heavy hadrons in charm and B factories.
Gang Li🇺🇸 · Michael Ramsey-Musolf🇨🇳 · Juan Carlos Vasquez🇺🇸
We study the impact of the mixing (LR mixing) between the standard model boson and its hypothetical, heavier right-handed parter on the neutrinoless double beta decay (-decay) rate. Our study is done in the minimal left-right symmetric model assuming type-II dominance scenario with charge conjugation as the left-right symmetry. We then show that the -decay rate may be dominated by the contribution proportional to this LR mixing, which at the hadronic level induces the leading-order contribution to the interaction between two pions and two charged leptons. The resulting long-range pion exchange contribution can significantly enhance the decay rate compared to previously considered short-range contributions. Finally, we find that even if future cosmological experiments rule out the inverted hierarchy for neutrino masses, there are still good prospects for a positive signal in the next generation of -decay experiments.
Wolfgang Altmannshofer🇺🇸 · Stefania Gori🇺🇸 · Nick Hamer🇺🇸 · Hiren H. Patel🇺🇸
We present the first complete two loop calculation of the electron EDM in the complex two-Higgs doublet model. We confirm gauge-independence by demonstrating analytic cancellation of the gauge parameter in the background field gauge and the 't Hooft gauge. We also investigate the behavior of the electron EDM near the decoupling limit, and determine the short- and long-distance contributions by matching onto an effective field theory. Compared with earlier studies of the electron EDM in the complex two-Higgs doublet model, we note disagreements in several places and provide diagnoses where possible. We also provide expressions for EDMs of light quarks.
We introduce a novel variational autoencoder (VAE) architecture that can generate realistic and diverse high energy physics events. The model we propose utilizes several techniques from VAE literature in order to simulate high fidelity jet images. In addition to demonstrating the model's ability to produce high fidelity jet images through various assessments, we also demonstrate its ability to control the events it generates from the latent space. This can be potentially useful for other tasks such as jet tagging, where we can test how well jet taggers can classify signal from background for events generated by the VAE. We test this idea by seeing the signal efficiency vs background rejection for different types of jet images produced by our model. We compare our VAE with generative adversarial networks (GAN) in several ways, most notably in speed. The architecture we propose is ultimately a fast, stable, and easy-to-train deep generative model that demonstrates the potential of VAEs in simulating high energy physics events.
Of the contributions to the cosmological constant, zero-point energy and self energy contributions scale as where is an ultraviolet cutoff used to regulate the calculations. I show that such contributions vanish when calculated in perturbation theory. This demonstration uses a little-known modification to perturbation theory found by Honerkamp and Meetz and by Gerstein, Jackiw, Lee and Weinberg which comes into play when using cutoffs and interactions with multiple derivatives, as found in chiral theories and gravity. In a path integral treatment, the new interaction arises from the path integral measure. This reduces the sensitivity of the cosmological constant to the high energy cutoff significantly, although it does not resolve the cosmological constant problem. The feature removes one of the common motivations for supersymmetry. It also calls into question some of the results of the Asymptotic Safety program. Covariance and quadratic cutoff dependence are also briefly discussed.
Zhou Liu🇨🇳 · Li-Hong Wen🇨🇳 · J.-F. Yang🇨🇳
Some one-loop diagrams with one and two external baryons/nucleons are revisited using covariant baryon propagators in chiral effective theory. We showed that it is enough to separate and subtract all the local terms that violate chiral power counting to recover chiral power counting, no need to introduce extra operations. The structures of leading chiral corrections and IR enhancement or threshold effects are 'stable' or persist as long as covariant propagators are employed for all particles.
Dibyendu Bala🇮🇳 · Saumen Datta🇮🇳
We investigate the interaction between a heavy quark-antiquark pair in color octet configuration in gluon plasma. We calculate nonperturbatively an effective thermal potential for such a pair through the study of the correlation function of a hybrid state with octet and an adjoint gluon source in the static limit. We discuss the extraction of an octet potential, and present results for the effective thermal potential between octet pair in gluon plasma for moderately high temperatures . The implications of our result are discussed.
Andrea Addazi🇨🇳 · Andy Buckley🇬🇧 · Jose Bellido🇦🇺 · Zhen Cao🇨🇳 · Ruben Conceição🇵🇹 · Lorenzo Cazon🇵🇹 · Armando di Matteo🇮🇹 · Bruce Dawson🇦🇺 · Kasumasa Kawata🇯🇵 · Paolo Lipari🇮🇹 · Analiza Mariazzi🇦🇷 · Marco Muzio🇺🇸 and 16 other authors
Air showers, produced by the interaction of energetic cosmic rays with the atmosphere, are an excellent alternative to study particle physics at energies beyond any human-made particle accelerator. For that, it is necessary to identify first the mass composition of the primary cosmic ray (and its energy). None of the existing high energy interaction models have been able to reproduce coherently all air shower observables over the entire energy and zenith angle phase space. This is despite having tried all possible combinations for the cosmic ray mass composition. This proposal outlines a self-consistent strategy to study high energy particle interactions and identify the energy spectra and mass composition of cosmic rays. This strategy involves the participation of different particle accelerators and astrophysics experiments. This is important to cover the entire cosmic ray energy range and a larger phase-space of shower observables to probe the high energy interaction models.
Nahuel Barrios🇺🇾 · Marcela Peláez🇺🇾 · Urko Reinosa🇫🇷 · Nicolás Wschebor🇺🇾
The Curci-Ferrari model has been shown to provide a good grasp on pure Yang-Mills correlation functions in the Landau gauge, already at one-loop order. In a recent work, the robustness of these results has been tested by evaluating the two-loop corrections to the gluon and ghost propagators. We pursue this systematic investigation by computing the ghost-antighost-gluon vertex to the same accuracy in a particular kinematic configuration that makes the calculations simpler. Because both the parameters of the model and the normalizations of the fields have already been fixed in a previous work, the present calculation represents both a pure prediction and a stringent test of the approach. We find that the two-loop results systematically improve the comparison to Monte-Carlo simulations as compared to earlier one-loop results. The improvement is particularly significative in the SU() case where the predicted ghost-antighost-gluon vertex is in very good agreement with the data. The same comparison in the SU() case is not as good, however. This may be due to the presence of a larger coupling constant in the infrared in that case although we note that a similar mismatch has been quoted in non-perturbative continuum approaches. Despite these features of the SU() case, it is possible to find sets of parameters fitting both the propagators and the ghost-antighost-gluon vertex to a reasonable accuracy.
Zheng Cao🇨🇳 · Lie-Wen Chen🇨🇳 · Peng-Cheng Chu🇨🇳 · Ying Zhou🇨🇳
Within a confining quark matter model which considers phenomenologically the quark confinement and asymptotic freedom as well as the chiral symmetry restoration and quark deconfinement at high baryon density, we find that if the up-down quark matter (QM) is more stable than nuclear matter and strange quark matter (SQM), the maximum mass of static quark stars with QM is under agreement with both the constraints on star tidal deformability from gravitational wave signal GW170817 and the mass-radius of PSR J0030+0451 and PSR J0740+6620 measured by NICER. In contrast, the conventional strange quark star with the SQM that is more stable than nuclear matter while the nuclear matter is more stable than QM, has a maximum static mass of only and its radius significantly deviates from NICER's constraint. Our results thus provide circumstantial evidence suggesting the recently reported GW190814's secondary component with a mass of could be an up-down quark star.
Mason C. Marshall🇺🇸 · Matthew J. Turner🇺🇸 · Mark J.H. Ku🇺🇸 · David F. Phillips🇺🇸 · Ronald L. Walsworth🇺🇸
Searches for WIMP dark matter will in the near future be sensitive to solar neutrinos. Directional detection offers a method to reject solar neutrinos and improve WIMP searches, but reaching that sensitivity with existing directional detectors poses challenges. We propose a combined atomic/particle physics approach using a large-volume diamond detector. WIMP candidate events trigger a particle detector, after which spectroscopy of nitrogen vacancy centers reads out the direction of the incoming particle. We discuss the current state of technologies required to realize directional detection in diamond and present a path towards a detector with sensitivity below the neutrino floor.
Catarina Cosme🇨🇦 · Tommi Tenkanen🇺🇸
It has been shown that the observed dark matter (DM) abundance can be produced by amplification of quantum fluctuations of an energetically subdominant scalar field during inflation. In this paper, we study the robustness of this "spectator dark matter" scenario to changes in the expansion rate of the early Universe. Compared to the standard radiation-dominated (RD) scenario, two aspects will change: the DM energy density evolves differently as a function of time, and also the DM isocurvature perturbation spectrum will be different from the result in the RD case. These can impose sizeable changes to the values of model parameters which allow the field to constitute all DM while simultaneously satisfying all observational constraints. We study both free and self-interacting DM in scenarios with non-standard expansion and quantify the changes to the cases with a standard cosmological history. We also discuss testability of the scenario through primordial DM isocurvature and non-Gaussianity.
Jeremy Sakstein🇺🇸 · Djuna Croon🇨🇦 · Samuel D. McDermott🇺🇸 · Maria C. Straight🇺🇸 · Eric J. Baxter🇺🇸
The LIGO/Virgo collaboration has recently announced the detection of a heavy binary black hole merger, with component masses that cannot be explained by standard stellar structure theory. In this letter we propose several explanations based on models of new physics, including new light particle losses, modified gravity, large extra dimensions, and a small magnetic moment of the neutrino. Each of these affect the physics of the pair-instability differently, leading to novel mechanisms for forming black holes inside the black hole mass gap.
Nashwan Sabti🇬🇧 · Julian B. Muñoz🇺🇸 · Diego Blas🇬🇧
UV luminosity functions provide a wealth of information on the physics of galaxy formation in the early Universe. Given that this probe indirectly tracks the evolution of the mass function of dark matter halos, it has the potential to constrain alternative theories of structure formation. One of such scenarios is the existence of primordial non-Gaussianity at scales beyond those probed by observations of the Cosmic Microwave Background. Through its impact on the halo mass function, such small-scale non-Gaussianity would alter the abundance of galaxies at high redshifts. In this work we present an application of UV luminosity functions as measured by the Hubble Space Telescope to constrain the non-Gaussianity parameter for wavenumbers above a cut-off scale . After marginalizing over the unknown astrophysical parameters and accounting for potential systematic errors, we arrive at a bound of for a cut-off scale in the bispectrum of the primordial gravitational potential. Moreover, we perform forecasts for the James Webb Space Telescope and the Nancy Grace Roman Space Telescope, finding an expected improvement of a factor upon the current bound.
* 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.