Mon·Jul 20, 2020Monday·July 20, 2020

1. 01*

   Heavy dark matter through the dilaton portal

   Benjamin Fuks🇫🇷 · Mark D. Goodsell🇫🇷 · Dong Woo Kang🇰🇷 · Pyungwon Ko🇰🇷 · Seung J. Lee🇰🇷 · Manuel Utsch🇫🇷

   We re-examine current and future constraints on a heavy dilaton coupled to a simple dark sector consisting of a Majorana fermion or a Stückelberg vector field. We include three different treatments of dilaton-Higgs mixing, paying particular attention to a gauge-invariant formulation of the model. Moreover, we also invite readers to re-examine effective field theories of vector dark matter, which we show are missing important terms. Along with the latest Higgs coupling data, heavy scalar search results, and dark matter density/direct detection constraints, we study the LHC bounds on the model and estimate the prospects of dark matter production at the future HL-LHC and 100 TeV FCC colliders. We additionally compute novel perturbative unitarity constraints involving vector dark matter, dilaton and gluon scattering.

   hep-phJHEP(2020)·9 citations
2. 02*

   Anomaly-free $U(1{)}^m$ extensions of the Standard Model

   Davi B. Costa🇧🇷

   We construct anomaly-free $U(1{)}_1\times U(1{)}_2\times ...\times U(1{)}_m$ gauge extensions of the Standard Model. To perform this construction we put together anomaly-free $U(1)$ extensions of one and two families of fermions. The availability of free parameters that enter linearly in the equations for the fermion charges and the large number of different classes of extensions may help other model builders interested in their use to solve problems of particle physics.

   hep-phhep-thPRD(2020)·16 citations
3. 03*

   Effective Theory of Freeze-in Dark Matter

   Basabendu Barman🇮🇳 · Debasish Borah🇮🇳 · Rishav Roshan🇮🇳

   We perform a model independent study of freeze-in of massive particle dark matter (DM) by adopting an effective field theory framework. Considering the dark matter to be a gauge singlet Majorana fermion, odd under a stabilising symmetry $Z_2$ under which all standard model (SM) fields are even, we write down all possible DM-SM operators upto and including mass dimension eight. For simplicity of the numerical analysis we restrict ourselves only to the scalar operators in SM as well as in the dark sector. We calculate the DM abundance for each such dimension of operator considering both UV and IR freeze-in contributions which can arise before and after the electroweak symmetry breaking respectively. After constraining the cut-off scale and reheat temperature of the universe from the requirement of correct DM relic abundance, we also study the possibility of connecting the origin of neutrino mass to the same cut-off scale by virtue of lepton number violating Weinberg operators. We thus compare the bounds on such cut-off scale and corresponding reheat temperature required for UV freeze-in from the origin of light neutrino mass as well as from the requirement of correct DM relic abundance. We also briefly comment upon the possibilities of realising such DM-SM effective operators in a UV complete model.

   hep-phJCAP(2020)·51 citations
4. 04*

   Lepton flavour violation from an anomaly-free leptophilic axion-like particle

   C. Han🇨🇳 · M.L. López-Ibáñez🇨🇳 · A. Melis🇪🇸 · O. Vives🇪🇸 · J. M. Yang🇨🇳

   Motivated by the recent Xenon1T result, we study a leptophilic flavour-dependent anomaly-free axion-like particle (ALP) and its effects on charged-lepton flavour violation (CLFV). We present two representative models. The first one considers that the ALP origins from the flavon that generates the charged-lepton masses. The second model assumes a larger flavour symmetry such that more general mixings in the charged-lepton are possible, while maintaining flavour-dependent ALP couplings. We find that a keV ALP explaining the Xenon1T result is still viable for lepton flavour violation and stellar cooling astrophysical limits. On the other hand, if the Xenon1T result is confirmed, future CLFV measurements can be complementary to probe such a possibility.

   hep-phastro-ph.COPRD(2021)·42 citations
5. 05*

   Light Majorana Neutrinos in (Semi)invisible Meson Decays

   Blaz Bortolato🇸🇮 · Jernej F. Kamenik🇸🇮

   We reconsider decays of pseudoscalar mesons (P) to neutrino pairs and possibly additional photons in presence of (light) Majorana neutrinos. For this purpose we derive a model-independent general parametrization of neutrino mass matrices with physically interpretable and irreducible set of parameters. The parametrization is valid for any number of neutrinos and interpolates smoothly between the heavy Majorana and the (pseudo)Dirac neutrino limits. We apply the new parametrization to the study of $P\to \nu \nu$ and $P\to \nu \nu \gamma$ decays within the SM extended by additional singlet fermions. We update the SM predictions for the branching ratios of $B_{s,d}\to \nu \nu \gamma$ and discuss the sensitivity of the $B_{s,d}\to E_{\mathrm{miss}}(\gamma )$ decays to neutrino mass and mixing parameters.

   hep-phEPJC(2021)·5 citations
6. 06*

   Electroweak corrections to the angular coefficients in finite-$p_T$ $Z$-boson production and dilepton decay

   Rikkert Frederix🇸🇪 · Timea Vitos🇸🇪

   We present next-to-leading order (NLO) electroweak corrections to the dominant five angular coefficients parametrizing the Drell-Yan process in the $Z$-boson mass peak range for finite-$p_T$ vector boson production. The results are presented differentially in the vector boson transverse momentum. The Lam-Tung violating difference $A_0-A_2$ is examined alongside the coefficients. A single lepton transverse momentum cut is needed in the case of electroweak corrections to avoid a double singularity in the photon induced diagrams, and the dependence on the value of this cut is examined. We compare the electroweak corrections to the angular coefficients to the NLO QCD corrections, including the single lepton cut. The size of the single lepton cut is found to affect the two coefficients $A_0$ and $A_2$ to largest extent. The relative size of the electroweak corrections to the coefficients is moderate for all single lepton cut values, and by extrapolation to the inclusive results, is moderate also for the full dilepton phase space case. However, for the Lam-Tung violation, there is a significant contribution from the electroweak corrections for low $p_T$ of the lepton pair.

   hep-phEPJC(2020)·17 citations
7. 07*

   Three-Body Non-Leptonic Heavy-to-heavy $B$ Decays at NNLO in QCD

   Tobias Huber🇩🇪 · Javier Virto🇪🇸 · K. Keri Vos🇩🇪

   Exclusive non-leptonic two-body decays of $B$ mesons have been studied extensively in the past two decades within the framework of factorization. However, the exploration of the corresponding three-body case has only started recently, in part motivated by new data. We consider here the simplest non-leptonic three-body $B$ decays from the point of view of factorization, namely heavy-to-heavy transitions. We provide a careful derivation of the SCET/QCDF factorized amplitudes to NNLO in ${\alpha }_s$, and discuss the numerical impact of NLO and NNLO corrections. We then study the narrow-width limit, showing that the three-body amplitude reproduces analytically the known quasi-two-body decay amplitudes, and compute finite-width corrections. Finally, we discuss certain observables that are sensitive to perturbative NLO and NNLO corrections and to higher Gegenbauer moments of the dimeson LCDAs. This is the first study of non-leptonic three-body $B$ decays to NNLO in QCD.

   hep-phhep-exhep-latJHEP(2020)·25 citations
8. 08*

   Canonical seesaw implication for two-component dark matter

   Phung Van Dong🇻🇳 · Cao H. Nam🇻🇳 · Duong Van Loi🇻🇳

   We show that the canonical seesaw mechanism implemented by the $U(1{)}_{B-L}$ gauge symmetry provides two-component dark matter naturally. The seesaw scale that breaks $B-L$ defines a residual gauge symmetry to be $Z_6=Z_2\otimes Z_3$, where $Z_2$ leads to the usual matter parity, while $Z_3$ is newly recognized, transforming quark fields nontrivially. The dark matter components -- that transform nontrivially under the matter parity and $Z_3$, respectively -- can gain arbitrary masses, despite the fact that the $Z_3$ dark matter may be heavier than the light quarks $u,d$. This dark matter setup can address the XENON1T anomaly recently observed and other observables, given that the dark matter masses are nearly degenerate, heavier than the electron and the $B-L$ gauge boson $Z^{\prime }$, as well as the fast-moving $Z_3$ dark matter has a large $B-L$ charge, while the $Z^{\prime }$ is viably below the beam dump experiment sensitive regime.

   hep-phPRD(2021)·20 citations
9. 09*

   Impact of LHC vector boson production in heavy ion collisions on strange PDFs

   A. Kusina🇵🇱 · T. Ježo🇩🇪 · D.B. Clark🇺🇸 · P. Duwentäster🇩🇪 · E. Godat🇺🇸 · T.J. Hobbs🇺🇸 · J. Kent🇺🇸 · M. Klasen🇩🇪 · K. Kovařík🇩🇪 · F. Lyonnet🇺🇸 · K.F. Muzakka🇩🇪 · F.I. Olness🇺🇸 · I. Schienbein🇫🇷 · J.Y. Yu🇺🇸

   The extraction of the strange quark parton distribution function (PDF) poses a long-standing puzzle. Measurements from neutrino-nucleus deep inelastic scattering (DIS) experiments suggest the strange quark is suppressed compared to the light sea quarks, while recent studies of W/Z boson production at the LHC imply a larger strange component at small x values. As the parton flavor determination in the proton depends on nuclear corrections, e.g. from heavy-target DIS, LHC heavy ion measurements can provide a distinct perspective to help clarify this situation. In this investigation we extend the nCTEQ15 nPDFs to study the impact of the LHC proton-lead W/Z production data on both the flavor differentiation and nuclear corrections. This complementary data set provides new insights on both the LHC W/Z proton analyses and the neutrino-nucleus DIS data. We identify these new nPDFs as nCTEQ15WZ. Our calculations are performed using a new implementation of the nCTEQ code (nCTEQ++) based on C++ which enables us to easily interface to external programs such as HOPPET, APPLgrid and MCFM. Our results indicate that, as suggested by the proton data, the small x nuclear strange sea appears larger than previously expected, even when the normalization of the W/Z data is accommodated in the fit. Extending the nCTEQ15 analysis to include LHC W/Z data represents an important step as we advance toward the next generation of nPDFs.

   hep-phEPJC(2020)·72 citations
10. 10*

    Dark matter models for the 511 keV galactic line predict keV electron recoils on Earth

    Yohei Ema🇩🇪 · Filippo Sala🇫🇷 · Ryosuke Sato🇩🇪

    We propose models of Dark Matter that account for the 511 keV photon emission from the Galactic Centre, compatibly with experimental constraints and theoretical consistency, and where the relic abundance is achieved via p-wave annihilations or, in inelastic models, via co-annihilations. Due to the Dark Matter component that is inevitably upscattered by the Sun, these models generically predict keV electron recoils at detectors on Earth, and could naturally explain the excess recently reported by the XENON1T collaboration. The very small number of free parameters make these ideas testable by detectors like XENONnT and Panda-X, by accelerators like NA64 and LDMX, and by cosmological surveys like the Simons observatory and CMB-S4. As a byproduct of our study, we recast NA64 limits on invisibly decaying dark photons to other particles.

    hep-phastro-ph.GAhep-exEPJC(2021)·37 citations
11. 11*

    ULYSSES: Universal LeptogeneSiS Equation Solver

    Alessandro Granelli🇮🇹 · Kristian Moffat🇬🇧 · Yuber Perez-Gonzalez🇺🇸 · Holger Schulz🇺🇸 · Jessica Turner🇺🇸

    ULYSSES is a python package that calculates the baryon asymmetry produced from leptogenesis in the context of a type-I seesaw mechanism. The code solves the semi-classical Boltzmann equations for points in the model parameter space as specified by the user. We provide a selection of predefined Boltzmann equations as well as a plugin mechanism for externally provided models of leptogenesis. Furthermore, the ULYSSES code provides tools for multi-dimensional parameter space exploration. The emphasis of the code is on user flexibility and rapid evaluation. It is publicly available at https://github.com/earlyuniverse/ulysses

    hep-phComput.Phys.Commun.(2021)·58 citations
12. 12*

    Testing quasi-Dirac leptogenesis through neutrino oscillations

    C. S. Fong🇧🇷 · T. Gregoire🇺🇸 · A. Tonero🇨🇦

    The lightness of the Standard Model (SM) neutrinos could be understood if their masses were to be generated by new physics at a high scale, through the so-called seesaw mechanism involving heavy fermion singlets. If new physics violates baryon minus lepton number by only a small amount, the heavy fermion singlets as well as the SM neutrinos split into pairs of quasi-Dirac states. At the scale of the fermion singlets, this quasi-Diracness allows to enhance CP violation in their decays and the cosmic matter-antimatter asymmetry can be successfully generated through resonant leptogenesis. At lower scale, this quasi-Diracness results in small SM neutrino mass splitting which can be probed in oscillation experiments. Remarkably, the parameter space for viable leptogenesis spans over the regime relevant for solar and atmospheric neutrino oscillations.

    hep-phPLB(2021)·9 citations
13. 13*

    Going beyond the minimal texture of quark mass matrices in the era of precision measurements

    Aakriti Bagai🇵🇰 · Shivali Kaundal🇵🇰 · Gulsheen Ahuja🇵🇰 · Manmohan Gupta🇮🇳

    An attempt has been made to carry out a detailed analysis of quark mass matrices having structure beyond the minimal texture. In particular, keeping in mind, precision measurements of CKM parameters as well as refinements in the ranges of light quark masses, we have examined the viability of all possible combinations of hermitian texture 5 zero quark mass matrices. Interestingly, one finds that all these possibilities are now excluded by the present quark mixing data, thereby, having important implications for model building.

    hep-phPTEP(2020)·2 citations
14. 14*

    Gravitational-Wave Lunar Observatory for Cosmology

    Karan Jani🇺🇸 · Abraham Loeb🇺🇸

    Several large-scale experimental facilities and space-missions are being suggested to probe the universe across the gravitational-wave (GW) spectrum. Here we propose Gravitational-wave Lunar Observatory for Cosmology (GLOC) - the first concept design in the NASA Artemis era for a GW observatory on the Moon. Using feasible interferometer technologies, we find that a lunar-based observatory is ideal for probing GW frequencies in the range between deci-Hz to 5 Hz, an astrophysically rich regime that is very challenging for both Earth- and space-based detectors. GLOC can survey binaries with neutron stars, stellar and intermediate-mass black holes to $\gtrsim 70\%$ of the observable volume of our universe without significant background contamination. The sensitivity at $\mathcal{O}(1\mathrm{Hz})$ allows a unique window into calibrating Type Ia supernovae. At its ultimate sensitivity limits, GLOC would trace the Hubble expansion rate up to redshift $z\sim 3$ and test General Relativity and $\Lambda$CDM cosmology up to $z\sim 350$.

    ↳ gr-qcastro-ph.COhep-phJCAP(2021)·56 citations
15. 15*

    Complex Langevin calculations in QCD at finite density

    Yuta Ito🇯🇵 · Hideo Matsufuru🇯🇵 · Yusuke Namekawa🇯🇵 · Jun Nishimura🇯🇵 · Shinji Shimasaki🇯🇵 · Asato Tsuchiya🇯🇵 · Shoichiro Tsutsui🇯🇵

    We demonstrate that the complex Langevin method (CLM) enables calculations in QCD at finite density in a parameter regime in which conventional methods, such as the density of states method and the Taylor expansion method, are not applicable due to the severe sign problem. Here we use the plaquette gauge action with $\beta =5.7$ and four-flavor staggered fermions with degenerate quark mass $ma=0.01$ and nonzero quark chemical potential $\mu$. We confirm that a sufficient condition for correct convergence is satisfied for $\mu /T=5.2-7.2$ on a $8^3\times 16$ lattice and $\mu /T=1.6-9.6$ on a $16^3\times 32$ lattice. In particular, the expectation value of the quark number is found to have a plateau with respect to $\mu$ with the height of 24 for both lattices. This plateau can be understood from the Fermi distribution of quarks, and its height coincides with the degrees of freedom of a single quark with zero momentum, which is 3 (color) $\times$ 4 (flavor) $\times$ 2 (spin) $=24$. Our results may be viewed as the first step towards the formation of the Fermi sphere, which plays a crucial role in color superconductivity conjectured from effective theories.

    ↳ hep-lathep-phJHEP(2020)·36 citations
16. 16*

    A non-linear duality-invariant conformal extension of Maxwell's equations

    Igor Bandos🇪🇸 · Kurt Lechner🇮🇹 · Dmitri Sorokin🇮🇹 · Paul K. Townsend🇬🇧

    All nonlinear extensions of the source-free Maxwell equations preserving both SO(2) electromagnetic duality invariance and conformal invariance are found, and shown to be limits of a one-parameter generalisation of Born-Infeld electrodynamics. The strong-field limit is the same as that found by Bialynicki-Birula from Born-Infeld theory but the weak-field limit is a new one-parameter extension of Maxwell electrodynamics, which is interacting but admits exact light-velocity plane-wave solutions of arbitrary polarisation. Small-amplitude waves on a constant uniform electromagnetic background exhibit birefringence, but one polarisation mode remains lightlike.

    ↳ hep-thhep-phphysics.class-phphysics.opticsPRD(2020)·315 citations
17. 17*

    Dealing with Nuisance Parameters using Machine Learning in High Energy Physics: a Review

    Tommaso Dorigo🇮🇹 · Pablo de Castro🇮🇹

    In this work we discuss the impact of nuisance parameters on the effectiveness of machine learning in high-energy physics problems, and provide a review of techniques that allow to include their effect and reduce their impact in the search for optimal selection criteria and variable transformations. The introduction of nuisance parameters complicates the supervised learning task and its correspondence with the data analysis goal, due to their contribution degrading the model performances in real data, and the necessary addition of uncertainties in the resulting statistical inference. The approaches discussed include nuisance-parameterized models, modified or adversary losses, semi-supervised learning approaches, and inference-aware techniques.

    ↳ stat.MLcs.LGhep-exhep-ph+125 citations
18. 18*

    Black Holes Lessons from Multipole Ratios

    Iosif Bena🇫🇷 · Daniel R. Mayerson🇫🇷

    We explain in detail how to calculate the gravitational mass and angular momentum multipoles of the most general non-extremal four-dimensional black hole with four magnetic and four electric charges. We also calculate these multipoles for generic supersymmetric four-dimensional microstate geometries and multi-center solutions. Both for Kerr black holes and BPS black holes many of these multipoles vanish. However, if one embeds these black holes in String Theory and slightly deforms them, one can calculate an infinite set of ratios of vanishing multipoles which remain finite as the deformation is taken away, and whose values are independent of the direction of deformation. For supersymmetric black holes, we can also compute these ratios by taking the scaling limit of multi-center solutions, and for certain black holes the ratios computed using the two methods agree spectacularly. For the Kerr black hole, these ratios pose strong constraints on the parameterization of possible deviations away from the Kerr geometry that should be tested by future gravitational wave interferometers.

    ↳ hep-thastro-ph.HEgr-qchep-phJHEP(2021)·80 citations
19. 19*

    Coulomb Corrections for Bose-Einstein Correlations from One- And Three-Dimensional Lévy-Type Source Functions

    Bálint Kurgyis🇭🇺 · Dániel Kincses🇭🇺 · Márton Nagy🇭🇺 · Máté Csanád🇭🇺

    In the study of femtoscopic correlations in high-energy physics, besides Bose--Einstein correlations, one has to take final-state interactions into account. Amongst them, Coulomb interactions play a prominent role in the case of charged particles. Recent measurements have shown that in heavy-ion collisions, Bose--Einstein correlations can be best described by Lévy-type sources instead of the more common Gaussian assumption. Furthermore, three-dimensional measurements have indicated that, depending on the choice of frame, a deviation from spherical symmetry observed under the assumption of Gaussian source functions persists in the case of Lévy-type sources. To clarify such three-dimensional Lévy-type correlation measurements, it is thus important to study the effect of Coulomb interactions in the case of non-spherical Lévy sources. We calculated the Coulomb correction factor numerically in the case of such a source function for assorted kinematic domains and parameter values using the Metropolis--Hastings algorithm and compared our results with previous methods to treat Coulomb interactions in the presence of Lévy sources.

    ↳ nucl-thhep-phUniverse(2023)·22 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.