Thu·Mar 26, 2020Thursday·March 26, 2020

1. 01*

   Disentangling new physics effects on non-resonant Higgs boson pair production from gluon fusion

   Kingman Cheung🇹🇼 · Adil Jueid🇰🇷 · Chih-Ting Lu🇰🇷 · Jeonghyeon Song🇰🇷 · Yeo Woong Yoon🇰🇷

   There are two kinds of new physics effects on non-resonant di-Higgs process from gluon fusion, non-SM Higgs trilinear self-coupling ${\lambda }_{hhh}$ or new colored particles running in the loop. With the aim of disentangling different new physics contributions, we study their characteristics in the kinematic distributions. Assuming that the total cross section is observed to be about three times as large as the SM expectation, we consider the cases of ${\lambda }_{hhh}/{\lambda }_{hhh}^{\mathrm{SM}}=-0.5,5.5$ as well as a new physics model with heavy vectorlike quarks in a type-II two Higgs double model, called the VLQ-2HDM. A reasonable benchmark point is suggested in the exact wrong-sign limit, where the opposite sign between the up-type VLQ and down-type VLQ couplings to the Higgs boson causes the cancellation of their contributions to the single-Higgs production from gluon fusion. Because of the threshold effects from the heavy VLQs in the loop, the VLQ-2HDM accommodates the bumps in the distributions of the invariant mass of the Higgs boson pair ($M_{hh}$) and the transverse momentum of a Higgs boson ($p_T^h$). The positions of two bumps are closely related as $M_{hh}\simeq 2M_{\mathrm{VLQ}}$ and $p_T^h\simeq M_{\mathrm{VLQ}}$. In addition, the bumps located at the heavy VLQ mass naturally lift up the $M_{hh}$ and $p_T^h$ distributions into high-mass and high-$p_T^h$ regions. On the other hand, the non-SM Higgs trilinear coupling cases have the distributions shift into low $M_{hh}$ and $p_T^h$ regions. Therefore, the kinematic region with high $M_{hh}$ and high $p_T^h$ will be a smoking-gun signal for the VLQ-2HDM. Full HL-LHC simulations for the di-Higgs signals are also performed, confirming that the $b\bar{b}b\bar{b}$ final state can distinguish the VLQ-2HDM.

   hep-phhep-exPRD(2021)·23 citations
2. 02*

   Inverse magnetic catalysis -- how much do we know about?

   Aritra Bandyopadhyay🇨🇳 · Ricardo L S Farias🇧🇷

   Some of the advances made in the literature to understand the phase transitions of quark matter in the presence of strong magnetic field and finite temperature (zero quark chemical potential) are reviewed. We start by discussing the physics behind the Magnetic catalysis (MC) at zero/finite temperature and then focus on the lattice predictions for inverse magnetic catalysis (IMC) at high temperature and strong magnetic fields. Possible explanations for the IMC are covered as well. Finally, we discuss recent efforts to modify QCD (quantum chromodynamics) effective models in order to reproduce the IMC observed on the lattice simulations. We emphasize the fact that applying thermo-magnetic effects on the coupling constant of the NJL model significantly improve the effectiveness of the NJL model to obtain a reasonable physical description of hot and magnetized quark matter being in agreement with lattice results.

   hep-phhep-latnucl-thEur.Phys.J.ST(2021)·55 citations
3. 03*

   Probing $Z^{\prime }$ Mediated Charged Lepton Flavor Violation with Taus at the LHeC

   Stefan Antusch🇨🇭 · A. Hammad🇨🇭 · Ahmed Rashed🇺🇸

   While charged lepton flavor violation (cLFV) with taus is often expected to be largest in many extensions of the Standard Model (SM), it is currently much less constrained than cLFV with electrons and muons. We study the sensitivity of the LHeC to $e$-$\tau$ (and $e$-$\mu$) conversion processes $p{e}^{-}\to {\tau }^{-}+j$ (and $p{e}^{-}\to {\mu }^{-}+j$) mediated by a $Z^{\prime }$ with flavor-violating couplings to charged leptons in the $t$-channel. Compared to current tests at the LHC, where cLFV decays of the $Z^{\prime }$ (produced in the s-channel) are searched for, the LHeC has sensitivity to much higher $Z^{\prime }$ masses, up to O(10) TeV. For cLFV with taus, we find that the LHeC sensitivity from the process $p{e}^{-}\to {\tau }^{-}+j$ can exceed the current limits from collider and non-collider experiments in the whole considered $Z^{\prime }$ mass range (above $500$ GeV) by more than two orders of magnitude. In particular for extensions of the SM with a heavy $Z^{\prime }$, where direct production at colliders is kinematically suppressed, $e-\tau$ conversion at LHeC provides an exciting new discovery channel for this type of new physics.

   hep-phPLB(2020)·13 citations
4. 04*

   Per-Object Systematics using Deep-Learned Calibration

   Gregor Kasieczka🇩🇪 · Michel Luchmann🇩🇪 · Florian Otterpohl🇩🇪 · Tilman Plehn🇩🇪

   We show how to treat systematic uncertainties using Bayesian deep networks for regression. First, we analyze how these networks separately trace statistical and systematic uncertainties on the momenta of boosted top quarks forming fat jets. Next, we propose a novel calibration procedure by training on labels and their error bars. Again, the network cleanly separates the different uncertainties. As a technical side effect, we show how Bayesian networks can be extended to describe non-Gaussian features.

   hep-phSciPost Phys.(2020)·63 citations
5. 05*

   Second-order quark number susceptibility of deconfined QCD matter in the presence of a magnetic field

   Bithika Karmakar🇮🇳 · Najmul Haque🇮🇳 · Munshi G Mustafa🇮🇳

   Considering the strong field approximation we compute the hard thermal loop pressure at finite temperature and chemical potential of hot and dense deconfined QCD matter in lowest Landau level in one-loop order. We consider the anisotropic pressure in the presence of the strong magnetic field i.e., longitudinal and transverse pressure along parallel and perpendicular to the magnetic field direction. As a first effort, we compute and discuss the anisotropic quark number susceptibility of deconfined QCD matter in lowest Landau level. The longitudinal quark number susceptibility is found to increase with the temperature whereas the transverse one decreases with the temperature. We also compute the quark number susceptibility in the weak field approximation. We find that the thermomagnetic correction to the quark number susceptibility is very marginal in the weak field approximation.

   hep-phhep-latnucl-thPRD(2020)·14 citations
6. 06*

   Genuine Dilatons in Gauge Theories

   R. J. Crewther🇦🇺

   A genuine dilaton $\sigma$ allows scales to exist even in the limit of exact conformal invariance. In gauge theories, these may occur at an infrared fixed point (IRFP) ${\alpha }_{\text{IR}}$ through dimensional transmutation. These large scales at ${\alpha }_{\text{IR}}$ can be separated from small scales produced by ${\theta }_{\mu }^{\mu }$, the trace of the energy-momentum tensor. For quantum chromodynamics (QCD), the conformal limit can be combined with chiral $SU(3)\times SU(3)$ symmetry to produce chiral-scale perturbation theory $\chi$PT${}_{\sigma }$, with $f_0(500)$ as the dilaton. The technicolor (TC) analogue of this is crawling TC: at low energies, the gauge coupling $\alpha$ goes directly to (but does not walk past) ${\alpha }_{\text{IR}}$, and the massless dilaton at ${\alpha }_{\text{IR}}$ corresponds to a light Higgs boson at $\alpha \lesssim {\alpha }_{\text{IR}}$. It is suggested that the $W^{\pm }$ and $Z^0$ bosons set the scale of the Higgs boson mass. Unlike crawling TC, in walking TC, ${\theta }_{\mu }^{\mu }$ produces $all$ scales, large and small, so it is hard to argue that its ``dilatonic'' candidate for the Higgs boson is not heavy.

   hep-phhep-lathep-thUniverse(2020)·37 citations
7. 07*

   Joint lattice QCD - dispersion theory analysis confirms the quark-mixing top-row unitarity deficit

   Chien-Yeah Seng🇩🇪 · Xu Feng🇨🇳 · Mikhail Gorchtein🇩🇪 · Lu-Chang Jin🇺🇸

   Recently, the first ever lattice computation of the $\gamma W$-box radiative correction to the rate of the semileptonic pion decay allowed for a reduction of the theory uncertainty of that rate by a factor of $\sim 3$. A recent dispersion evaluation of the $\gamma W$-box correction on the neutron also led to a significant reduction of the theory uncertainty, but shifted the value of $V_{ud}$ extracted from the neutron and superallowed nuclear $\beta$ decay, resulting in a deficit of the CKM unitarity in the top row. A direct lattice computation of the $\gamma W$-box correction for the neutron decay would provide an independent cross-check for this result but is very challenging. Before those challenges are overcome, we propose a hybrid analysis, converting the lattice calculation on the pion to that on the neutron by a combination of dispersion theory and phenomenological input. The new prediction for the universal radiative correction to free and bound neutron $\beta$-decay reads ${\Delta }_R^V=0.02477(24)$, in excellent agreement with the dispersion theory result ${\Delta }_R^V=0.02467(22)$. Combining with other relevant information, the top-row CKM unitarity deficit persists.

   hep-phhep-exhep-latnucl-ex+1PRD(2020)·144 citations
8. 08*

   ${\gamma }^{\ast }N\to {\Delta }^{+}(1600)$ transition form factors in light-cone sum rules

   T.M. Aliev🇹🇷 · T. Barakat🇸🇦 · S. Bilmis🇹🇷 · M. Savci🇹🇷

   The form factors of ${\gamma }^{\ast }N\to \Delta (1600)$ transition is calculated within the light-cone sum rules assuming that ${\Delta }^{+}(1600)$ is the first radial excitation of $\Delta (1232)$. The $Q^2$ dependence of the magnetic dipole ${\tilde{G}}_M(Q^2)$, electric quadrupole ${\tilde{G}}_E(Q^2)$, and Coulomb quadrupole ${\tilde{G}}_c(Q^2)$ form factors are investigated. Moreover, the $Q^2$ dependence of the ratios $R_{EM}=-\frac{{\tilde{G}}_E(Q^2)}{{\tilde{G}}_M{Q}^2}$ and $R_{SM}=-\frac{1}{4m_{\Delta (1600)}^2}\sqrt{4m_{\Delta (1600)}^2{Q}^2+(m_{\Delta (1600)}^2-Q^2-m_N^2{)}^2}\frac{{\tilde{G}}_c(Q^2)}{{\tilde{G}}_M(Q^2)}$ are studied. Finally, our predictions on ${\tilde{G}}_M(Q^2)$, ${\tilde{G}}_E(Q^2)$, and ${\tilde{G}}_C(Q^2)$ are compared with the results of other theoretical approaches.

   hep-phPRD(2020)·2 citations
9. 09*

   Nonperturbative Flavor Breaking in Topological Susceptibility at Chiral Crossover

   Mamiya Kawaguchi🇨🇳 · Shinya Matsuzaki🇨🇳 · Akio Tomiya🇺🇸

   We demonstrate that the QCD topological susceptibility nonperturbatively gets a significant contribution signaled by flavor-nonuniversal quark condensates at around the pseudo-critical temperature of the chiral crossover. It implies a remarkable flavor breaking in the axial anomaly as well as the QCD theta vacuum in high temperature QCD, which are almost flavor universal in the vacuum. A nontrivial flavor breaking is triggered by nonperturbative thermal loop corrections at around the chiral crossover, which is different from the trivial flavor violation just scaled by the quark mass ratio, observed at asymptotically high temperatures. This critical flavor violation cannot be dictated by the chiral perturbation theory with that lattice QCD usually compares, or the dilute instanton gas approximation based on that its astrophysical implications have conventionally been made. This would give an impact on the thermal history and the cosmological evolution of QCD axion including the estimate of the relic abundance as a dark matter candidate.

   hep-phastro-ph.COhep-latnucl-thPLB(2021)·8 citations
10. 10*

    Dirac dark matter in a radiative neutrino model

    Hiroshi Okada🇰🇷 · Yutaro Shoji🇯🇵

    We propose a simple radiative neutrino mass scenario with a Dirac dark matter candidate, which is minimally realized by a Z3 symmetry. We introduce two Dirac neutrinos and two inert doublets. We demonstrate that the model has a large allowed region that satisfies the constraints from neutrino oscillation data, lepton flavor violations, direct/indirect detection of dark matter and dark matter relic density. We also propose an efficient parameterization of the neutrino Yukawa couplings, which reproduces a desired active neutrino mass matrix.

    hep-phPhys.Dark Univ.(2021)·24 citations
11. 11*

    One-loop Type II Seesaw Neutrino Model with Stable Dark Matter Candidates

    M. A. Loualidi🇲🇦 · M. Miskaoui🇲🇦

    Opening up the Weinberg operator at 1-loop level using a scalar triplet, two scalar doublets and one fermion gives rise to T4-2-i one-loop topology. Neutrino masses generated from this topology are always accompanied by the tree level Type II seesaw contribution. In this work, we propose a radiative Majorana neutrino mass model based on this topology where to avoid the tree level Type II seesaw mechanism, we extend the model by a $G_f={\mathbb{D}}_4\times Z_3\times Z_5\times Z_2$ flavor symmetry and we promote the fermion inside the loop to three right-handed neutrinos. In this scenario, the tree level Dirac neutrino masses resulted from these right-handed neutrinos is also prevented by the $G_f$ group. Moreover, in order for T4-2-i topology to fully function, the scalar sector is extended by two flavon fields where after $G_f$ symmetry breaking, the model accounts successfully for the observed neutrino masses and mixing as well as allows for the existence of stable dark matter (DM) candidates. Indeed, all the particles running in the loop are potential dark matter candidates as their stability is guaranteed by the unbroken discrete group $Z_2\in G_f$.

    hep-phNPB(2020)·7 citations
12. 12*

    A phenomenological analysis of the nonperturbative QCD contributions for the photon wave function

    V. P. Goncalves🇧🇷 · B. D. Moreira🇧🇷

    The photon -- induced interactions, present in $ep$, $eA$, $pp$, $pA$, $AA$ and $e^{+}{e}^{-}$ collisions, are expressed within the color dipole approach in terms of the photon wave function, which describes the transition of the photon into a quark -- antiquark color dipole. Such quantity is usually calculated using perturbation theory assuming that long distance corrections associated to strong interactions can be neglected. In this paper we investigate the impact of these nonperturbative QCD (npQCD) corrections to the description of the photon wave function for dipoles of large size in several observables measured at HERA, LEP and LHC. We assume a phenomenological ansatz for the treatment of these npQCD corrections and constrain the free parameters of our model using the experimental data for the photoproduction cross section. The predictions for the $\gamma \gamma$ cross section, exclusive $\rho$ production in $ep$ collisions and the rapidity distribution for the $\rho$ production in $PbPb$ collisions are compared with the data. We demonstrate that the inclusion of the nonperturbative QCD corrections improves the description of processes that are dominated by large dipoles.

    hep-phhep-exEPJC(2020)·14 citations
13. 13*

    Logarithmic Regge Pole

    S. D. Campos (Universidade Federal de São Carlos-CCTS/DFQM)🇧🇷

    This work presents the subtraction procedure and the Regge cut in the logarithmic Regge pole approach. The subtraction mechanism leads to the same asymptotic behavior as previously obtained in the non-subtraction case. The Regge cut, on the other hand, introduces a clear role to the non-leading contributions for the asymptotic behavior of the total cross section. From these results, one introduces some simple parameterization to fit the experimental data for the proton-proton and antiproton-proton total cross section above some minimum value up to the cosmic-ray. The fit parameters obtained are used to present predictions for the $\rho (s)$-parameter as well as to the elastic slope $B(s)$ at high energies.

    hep-phnucl-th2 citations
14. 14*

    Long-lived charged particles and multi-lepton signatures from neutrino mass models

    Carolina Arbeláez R🇨🇱 · Giovanna Cottin🇨🇱 · Juan Carlos Helo🇨🇱 · Martin Hirsch🇪🇸

    Lepton number violation (LNV) is usually searched for by the LHC collaborations using the same-sign di-lepton plus jet signature. In this paper we discuss multi-lepton signals of LNV that can arise with experimentally interesting rates in certain loop models of neutrino mass generation. Interestingly, in such models the observed smallness of the active neutrino masses, together with the high-multiplicity of the final states, leads in large parts of the viable parameter space of such models to the prediction of long-lived charged particles, that leave highly ionizing tracks in the detectors. We focus on one particular 1-loop neutrino mass model in this class and discuss its LHC phenomenology in some detail.

    hep-phPRD(2020)·20 citations
15. 15*

    Coherent Elastic Neutrino-Nucleus Scattering with directional detectors

    M. Abdullah🇺🇸 · D. Aristizabal Sierra🇨🇱 · Bhaskar Dutta🇺🇸 · Louis E. Strigari🇺🇸

    We study the sensitivity of detectors with directional sensitivity to coherent elastic neutrino-nucleus scattering (CE$\nu$NS), and how these detectors complement measurements of the nuclear recoil energy. We consider stopped pion and reactor neutrino sources, and use gaseous helium and fluorine as examples of detector material. We generate Standard Model predictions, and compare to scenarios that include new, light vector or scalar mediators. We show that directional detectors can provide valuable additional information in discerning new physics, and we identify prominent spectral features in both the angular and the recoil energy spectrum for light mediators, even for nuclear recoil energy thresholds as high as $\sim 50$ keV. Combined with energy and timing information, directional information can play an important role in extracting new physics from CE$\nu$NS experiments.

    hep-phhep-exnucl-exnucl-th+1PRD(2020)·30 citations
16. 16*

    Gravitational Anomalies in string-inspired Cosmologies: from Inflation to Axion Dark Matter?

    Nikolaos E. Mavromatos (King's College London)🇬🇧

    In this talk, I review briefly a scenario for the evolution of a string-inspired cosmological model, in which condensates of primordial gravitational waves (GW), formed at the very early eras after the Big Bang, are considered responsible for inducing inflation and then a smooth exit to a radiation dominated epoch. Primordial axion fields, that exist in the fundamental massless gravitational (bosonic) string multiplet, couple to the non-trivial GW-induced anomalies. As a result of this coupling, there exist axion background configurations which violate (spontaneously) Lorentz symmetry, and remain undiluted at the end of inflation. In models with heavy sterile right-handed neutrinos (RHN), such backgrounds are linked to novel (Lorentz and CPT Violating) mechanisms for the generation of matter-antimatter asymmetry in the Cosmos, via the asymmetric decays of the RHN to standard model particles and antiparticles. During the QCD epoch, the axions develop an instanton-induced mass and can, thus, play the rôle of Dark Matter (DM). The energy density of such a Universe, throughout its evolution, has the form of that of a "running vacuum model", that is, it can be expanded in power series of even powers of the Hubble parameter $H(t)$. The coefficients of those terms, though, are different for the various cosmological epochs. For the phenomenology of our model, which is consistent with the current cosmological data, and could also help in alleviating (some of) the tensions, it suffices to consider up to and including quartic powers of $H(t)$. In the early Universe phase, it is the $H^4(t)$ term, induced by the GW condensate of the gravitational anomaly, that drives inflation without the need for external inflaton fields.

    ↳ gr-qchep-phhep-thPoS(2020)·0 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.