Thu·Oct 3, 2019Thursday·October 3, 2019

1. 01*

   Multicomponent dark matter in extended $U(1{)}_{B-L}$: neutrino mass and high scale validity

   Subhaditya Bhattacharya🇮🇳 · Nabarun Chakrabarty🇮🇳 · Rishav Roshan🇮🇳 · Arunansu Sil🇮🇳

   Standard Model with right handed neutrinos charged under additional $U(1{)}_{B-L}$ gauge symmetry offer solutions to both dark matter (DM) problem and neutrino mass generation, although constrained severely from relic density, direct search and Higgs vacuum stability. We therefore investigate a multicomponent DM scenario augmented by an extra inert scalar doublet, that is neutral under $U(1{)}_{B-L}$, which aids to enlarge parameter space allowed by DM constraints and Higgs vacuum stability. The lightest right-handed neutrino and the $CP$-even inert scalar are taken as the dark matter candidates and constitute a two component dark matter framework as they are rendered stable by an unbroken ${\mathbb{Z}}_2\times {\mathbb{Z}}_2^{\prime }$ symmetry. DM-DM conversion processes turn out crucial to render requisite relic abundance in mass regions of the RH neutrino that do not appear in the stand-alone $U(1{)}_{B-L}$ scenario. In addition, the one-loop renormalisation group (RG) equations in this model demonstrate that the electroweak (EW) vacuum can be stabilised till $\sim 10^9$ GeV in a parameter region compatible with the observed relic, the direct detection bound and other relevant constraints.

   hep-phJCAP(2020)·35 citations
2. 02*

   Symbolic expressions for fully differential single top quark production cross section and decay width of polarized top quark in the presence of anomalous Wtb couplings

   Edward Boos🇷🇺 · Viacheslav Bunichev🇷🇺

   Spin correlations in the t-channel single top quark production and its subsequent decay are investigated for the case of contributions involving anomalous Wtb couplings. We obtain analytical expressions for the differential widths for the three-particle decay of a polarized t quark in its rest frame and also expressions for the differential cross sections of the full process of production and decay of the t quark ($2\to 4$) as a function of the energy of a charged lepton and two angles of orientation of the quantization axis of the t-quark spin. The expression is presented in the most general form for the case of real and imaginary vector and tensor anomalous Wtb couplings. We show that shapes of certain multidimensional kinematic distributions of final state particles are significantly different for the contributions proportional to different combinations of the anomalous couplings. The most noticeable differences appear in the shape of the surfaces of two-dimensional distributions, where one of the variables is the energy of a charged lepton and the other is one of the t-quark spin orientation angles. Observed properties are confirmed by two methods of computations either from the obtained symbolic expression for the differential cross sections of the full process of the polarized single top quark production with its subsequent decay or by means of the CompHEP program for the complete process involving the t-channel single top. In addition, using the obtained analytical expressions, we estimate the statistical accuracy of extracting values of the anomalous Wtb couplings for different levels of the expected integral luminosity at the LHC.

   hep-phhep-exPRD(2020)·11 citations
3. 03*

   Magnetic excitation in relativistic heavy ion collisions

   I. Danhoni🇧🇷 · F. S. Navarra🇧🇷

   In this note we study the conversion of nucleons into deltas induced by a strong magnetic field in ultraperipheral relativistic heavy ion collisions. The interaction Hamiltonian couples the magnetic field to the spin operator, which, acting on the spin part of the wave function, converts a spin 1/2 into a spin 3/2 state. We estimate this transition probability and calculate the cross section for delta production. This process can in principle be measured, since the delta moves close to the beam and decays almost exclusively into pions. Forward pions may be detected by forward calorimeters.

   hep-phPLB(2020)·8 citations
4. 04*

   Probing multi-step electroweak phase transition with multi-peaked primordial gravitational waves spectra

   António P. Morais🇵🇹 · Roman Pasechnik🇸🇪

   Multi-peaked spectra of the primordial gravitational waves are considered as a phenomenologically relevant source of information about the dynamics of sequential phase transitions in the early Universe. In particular, such signatures trace back to specific patterns of the first-order electroweak phase transition in the early Universe occurring in multiple steps. Such phenomena appear to be rather generic in multi-scalar extensions of the Standard Model. In a particularly simple extension of the Higgs sector, we have identified and studied the emergence of sequential long- and short-lasting transitions as well as their fundamental role in generation of multi-peaked structures in the primordial gravitational-wave spectrum. We discuss the potential detectability of these signatures by the proposed gravitational-wave interferometers.

   hep-phastro-ph.COgr-qchep-exJCAP(2020)·40 citations
5. 05*

   Top quark as a probe of heavy Majorana neutrino at the LHC and future collider

   Ning Liu · Zong-guo Si · Lei Wu · Hang Zhou · Bin Zhu

   Right-handed (RH) Majorana neutrinos play a crucial role in understanding the origin of neutrino mass, the nature of dark matter and the mechanism of matter-antimatter asymmetry. In this work, we investigate the observability of heavy Majorana neutrino through the top quark neutrinoless double beta decay process $t\to b{\ell }^{+}{\ell }^{+}jj$ at hadron colliders. By performing detector level simulation, we demonstrate that our method can give stronger limits on the light-heavy neutrino mixing parameters $|V_{eN,\mu N}|$ in the mass range of 15 GeV $<m_N<$ 80 GeV than other existing collider bounds.

   hep-phhep-exPRD(2020)·17 citations
6. 06*

   Exploring origin of small x saturation in collinear approach

   A.M. Snigirev🇷🇺 · G.M. Zinovjev🇺🇦

   A modification of the collinear evolution equations as an appropriate approach to improve the behavior of parton distribution functions in the region of small longitudinal momentum fractions, and to find more theoretical arguments to clarify the possible appearence of saturation regime is suggested. It is argued that parton diffusion in the rapidity space at large parton densities along the space-time evolution could result in the emergence of a natural saturation scale on which freezing actually occurs.

   hep-phPRD(2019)·2 citations
7. 07*

   Road map through the desert: unification with vector-like fermions

   Kamila Kowalska🇵🇱 · Dinesh Kumar🇵🇱

   In light of null results from New Physics searches at the LHC, we look at unification of the gauge couplings as a model-building principle. As a first step, we consider extensions of the Standard Model with vector-like fermions. We present a comprehensive list of spectra that feature fermions in two distinct $SU(3{)}_C\times SU(2{)}_L\times U(1{)}_Y$ representations, in which precise gauge coupling unification is achieved. We derive upper and lower limits on vector-like masses from proton decay measurements, running of the strong gauge coupling, heavy stable charged particle searches, and electroweak precision tests. We demonstrate that due to a particular hierarchy among the mass parameters required by the unification condition, complementarity of various experimental strategies allows us to probe many of the successful scenarios up to at least 10 TeV.

   hep-phJHEP(2019)·12 citations
8. 08*

   Charmed baryon decays in $SU(3{)}_F$ symmetry

   Cai-Ping Jia🇨🇳 · Di Wang🇨🇳 · Fu-Sheng Yu🇨🇳

   In the recent years, fruitful results on charmed baryons are obtained by BESIII, Belle and LHCb. We investigate the two-body non-leptonic decays of charmed baryons in the flavor $SU(3)$ symmetry. Hundreds of amplitude relations are clearly provided, and are classified according to the $I$-, $U$- and $V$-spin symmetries. Among them, some amplitude relations are tested by the experimental data, or used to predict the branching fractions based on the exact flavor symmetry without any other approximation. Some relations of $K_S^0-K_L^0$ asymmetries and $CP$ asymmetries are obtained under the $U$-spin symmetry in the modes of charmed baryon decaying into neutral kaons. Besides, the $U$-spin breaking effect is explored in the ${\Lambda }_c^{+}\to {\Sigma }^{+}{K}^{\ast 0}$ and ${\Xi }_c^{+}\to p{\bar{K}}^{\ast 0}$ modes.

   hep-phNPB(2020)·43 citations
9. 09*

   Sensitivity to Atypical Tau Initiated Air Showers For a High-Altitude Optical Cherenkov Detector

   Austin Cummings🇮🇹 · Roberto Aloisio🇮🇹 · Mario Bertaina🇮🇹 · Francesca Bisconti🇮🇹 · Francesco Fenu🇮🇹 · Francesco Salamida🇮🇹

   The ANITA collaboration has recently announced the supposed observation of two upward going cosmic ray showers at earth emergence angles $27^{\circ }$ and $35^{\circ }$ with reconstructed energy $\sim$0.6~EeV. Upward air showers (UAS) are expected from tau leptons resulting from the interaction of astrophysical neutrinos inside the Earth. However, at emergence angles larger than $20^{\circ }$, the probability of tau emergence from a neutrino is less than $10^{-7}$, which makes a standard model explanation for these signals difficult. If confirmed by other experiments, these energetic events would strengthen the argument for physics beyond the standard model. Both the proposed EUSO-SPB2 and the POEMMA instruments will be equipped with optical Cherenkov detectors in order to measure the Cherenkov emission from UAS, which, if aimed low enough below the horizon, could, in principle, capture these events as well. An observation in the Cherenkov channel would help to rule out anthropogenic and other explanations for these events. We present here the sensitivity to the ANITA anamolous events for a balloon based and a satellite based Cherenkov detector, as could be realized in the upcoming EUSO-SPB2 mission and the proposed POEMMA mission, respectively.

   hep-phastro-ph.IMPoS(2020)·1 citation
10. 10*

    A More Complete Phenomenology of Tau Lepton Induced Air Showers

    Austin Cummings🇮🇹 · Roberto Aloisio🇮🇹 · Mario Bertaina🇮🇹 · Francesca Bisconti🇮🇹 · Francesco Fenu🇮🇹 · Francesco Salamida🇮🇹

    Many proposed and upcoming experiments seek to observe signals from upward going air showers initiated by tau leptons resulting from neutrino interactions inside the Earth. To save calculation time, event estimations for these observation methods are usually performed while making several assumptions about the showers themselves, which simplifies their rich phenomenology and may or may not lead to inaccuracies in results. Here, we present results of extensive CORSIKA simulations of upward going tau initiated showers in the energy range 1 PeV to 10 EeV. Specifically, we monitor the Cherenkov emission, the charged particle distributions, and the timing of the showers for different geometric configurations. We analyze the impact of the decay length and different decay modes of the tau on particle distributions and compare to primaries usually utilized to simulate a tau shower, such as gammas, electrons, and protons. We also check the accuracy of many of the usual assumptions of these showers and analyze the often ignored muon channel of the tau decay.

    hep-phPoS(2020)·5 citations
11. 11*

    Momentum mappings for subtractions at higher orders in QCD

    Vittorio Del Duca🇨🇭 · Nicolas Deutschmann🇨🇭 · Simone Lionetti🇨🇭

    Subtraction schemes provide a systematic way to compute fully-differential cross sections beyond the leading order in the strong coupling constant. These methods make singular real-emission corrections integrable in phase space by the addition of suitable counterterms. Such counterterms may be defined using momentum mappings, which are parametrisations of the phase space that factorise the variables that describe the particles becoming unresolved in some infrared or collinear limit from the variables that describe an on-shell phase space for the resolved particles. In this work, we review existing momentum mappings in a unified framework and introduce new ones for final-collinear and soft counterterms. The new mappings work in the presence of massive particles and with an arbitrary number of soft particles or of clusters of collinear particles, making them fit for subtraction methods at any order in perturbation theory. The new mapping for final-collinear counterterms is also used to elucidate relations among existing final-collinear mappings.

    hep-phJHEP(2019)·15 citations
12. 12*

    Gravitational traces of broken gauge symmetries

    Aleksandr Azatov🇮🇹 · Daniele Barducci🇮🇹 · Francesco Sgarlata🇮🇹

    We investigate first order phase transitions arising from hidden sectors which are in thermal equilibrium with the Standard Model bath in the Early Universe. Focusing on two simplified scenarios, an higgsed U(1) and a two scalar singlet model, we show the impact of friction effects acting on the bubble walls on the gravitational wave spectra and on the consequences for present and future interferometer experiments. We further comment on the possibility of disentangling the properties of the underlying theory featuring the first order phase transition should a stochastic gravitational wave signal be discovered.

    hep-phJCAP(2020)·50 citations
13. 13*

    On the Impact of Neutrino Decays on the Supernova Neutronization-Burst Flux

    André de Gouvêa🇺🇸 · Ivan Martinez-Soler🇺🇸 · Manibrata Sen🇺🇸

    The discovery of non-zero neutrino masses invites one to consider decays of heavier neutrinos into lighter ones. We investigate the impact of two-body decays of neutrinos on the neutronization burst of a core-collapse supernova -- the large burst of ${\nu }_e$ during the first 25 ms post core-bounce. In the models we consider, the ${\nu }_e$, produced mainly as a ${\nu }_3({\nu }_2)$ in the normal (inverted) mass ordering, are allowed to decay to ${\nu }_1({\nu }_3)$ or ${\bar{\nu }}_1({\bar{\nu }}_3)$, and an almost massless scalar. These decays can lead to the appearance of a neutronization peak for a normal mass ordering or the disappearance of the same peak for the inverted one, thereby allowing one mass ordering to mimic the other. Simulating supernova-neutrino data at the Deep Underground Neutrino Experiment (DUNE) and the Hyper-Kamiokande (HK) experiment, we compute their sensitivity to the neutrino lifetime. We find that, if the mass ordering is known, and depending on the nature of the Physics responsible for the neutrino decay, DUNE is sensitive to lifetimes $\tau /m\lesssim 10^6$ s/eV for a galactic SN sufficiently close-by (around 10 kpc), while HK is sensitive to lifetimes $\tau /m\lesssim 10^7$ s/eV. These sensitivities are far superior to existing limits from solar-system-bound oscillation experiments. Finally, we demonstrate that using a combination of data from DUNE and HK, one can, in general, distinguish between decaying Dirac neutrinos and decaying Majorana neutrinos.

    hep-phastro-ph.COastro-ph.SRhep-exPRD(2020)·50 citations
14. 14*

    Non-Minimal Dark Sectors: Mediator-Induced Decay Chains and Multi-Jet Collider Signatures

    Keith R. Dienes🇺🇸 · Doojin Kim🇺🇸 · Huayang Song🇺🇸 · Shufang Su🇺🇸 · Brooks Thomas🇺🇸 · David Yaylali🇺🇸

    A preponderance of astrophysical and cosmological evidence indicates that the universe contains not only visible matter but also dark matter. In order to suppress the couplings between the dark and visible sectors, a standard assumption is that these two sectors communicate only through a mediator. In this paper we make a simple but important observation: if the dark sector contains multiple components with similar quantum numbers, then this mediator also generically gives rise to dark-sector decays, with heavier dark components decaying to lighter components. This in turn can even give rise to relatively long dark decay chains, with each step of the decay chain also producing visible matter. The visible byproducts of such mediator-induced decay chains can therefore serve as a unique signature of such scenarios. In order to examine this possibility more concretely, we examine a scenario in which a multi-component dark sector is connected through a mediator to Standard-Model quarks. We then demonstrate that such a scenario gives rise to multi-jet collider signatures, and we examine the properties of such jets at both the parton and detector levels. Within relatively large regions of parameter space, we find that such multi-jet signatures are not excluded by existing monojet and multi-jet searches. Such decay cascades therefore represent a potential discovery route for multi-component dark sectors at current and future colliders.

    hep-phhep-exPRD(2020)·22 citations
15. 15*

    Leptonic Scalars at the LHC

    André de Gouvêa🇺🇸 · P. S. Bhupal Dev🇺🇸 · Bhaskar Dutta🇺🇸 · Tathagata Ghosh🇺🇸 · Tao Han🇺🇸 · Yongchao Zhang🇺🇸

    We explore the collider prospects of neutrino non-standard interaction with a Standard Model (SM) gauge-singlet leptonic scalar $\varphi$ carrying two units of lepton-number-charge. These leptonic scalars are forbidden from interacting with the SM fermions at the renormalizable level and, if one allows for higher-dimensional operators, couple predominantly to SM neutrinos. For masses at or below the electroweak scale, $\varphi$ decays exclusively into neutrinos. Its characteristic production signature at hadron collider experiments like the LHC would be via the vector boson fusion process and leads to same-sign dileptons, two forward jets in opposite hemispheres, and missing transverse energy, i.e., $pp\to {\ell }_{\alpha }^{\pm }{\ell }_{\beta }^{\pm }jj+E_T^{\mathrm{miss}}$ ($\alpha ,\beta =e,\mu ,\tau$). Exploiting the final states of electrons and muons, we estimate, for the first time, the sensitivity of the LHC to these lepton-number-charged scalars. We show that the LHC sensitivity is largely complementary to that of low-energy precision measurements of the decays of charged leptons, charged mesons, $W$, $Z$ and the SM Higgs boson, as well as the neutrino beam experiments like MINOS, and searches for neutrino self-interactions at IceCube and in cosmological observations. For $\varphi$ mass larger than roughly 10 GeV, our projected LHC sensitivity would surpass all existing bounds.

    hep-phhep-exJHEP(2020)·61 citations
16. 16*

    The hadronic vacuum polarization contribution to $(g_{\mu }-2)$: Lattice QCD+QED calculations

    Davide Giusti🇮🇹 · Silvano Simula🇮🇹

    The anomalous magnetic moment of the muon $a_{\mu }$ is one of the most accurate quantities in Particle Physics. The long-standing discrepancy of about $3.7$ standard deviations between the experimental value and the prediction of the Standard Model could represent an intriguing indication of New Physics. The experiments at Fermilab (E989) and at J-PARC (E34) aim at reducing significantly the experimental uncertainty, thus making the theoretical one due to hadronic corrections the main limitation of this stringent test of the Standard Model. In this contribution we present the results of a first-principles lattice calculation of the hadronic vacuum polarization (HVP) contribution to $a_{\mu }$, including electromagnetic and $SU(2)$-breaking corrections. Our determination, $a_{\mu }^{\mathrm{HVP}}=682.0(18.7)\cdot 10^{-10}$, turns out to be in agreement with recent theoretical determinations based on the dispersive analyses of the experimental cross section data for the annihilation process $e^{+}{e}^{-}\to hadrons$. Furthermore, we provide for the first time a lattice estimate for the missing part of $a_{\mu }^{\mathrm{HVP}}$ not covered in the MUonE experiment, ${\left[a_{\mu }^{\mathrm{HVP}}\right]}_{>}=91.6(2.0)\cdot 10^{-10}$.

    ↳ hep-lathep-exhep-phNuovo Cim.C(2020)·3 citations
17. 17*

    From Heisenberg-Euler Lagrangian to the discovery of chromomagnetic gluon condensation

    George Savvidy🇬🇷

    I reexamine the phenomena of the chromomagnetic gluon condensation in Yang-Mills theory. The extension of the Heisenberg-Euler Lagrangian to the Yang-Mills theory allows to calculate the effective action, the energy-momentum tensor and demonstrate that the energy density curve crosses the zero energy level of the perturbative vacuum state at nonzero angle and continuously enters to the negative energy density region. At the crossing point and further down the effective coupling constant is small and demonstrate that the true vacuum state of the Yang-Mills theory is below the perturbative vacuum state and is described by the nonzero chromomagnetic gluon condensate. The renormalisation group analysis allows to express the energy momentum tensor, its trace and the first and second order derivatives in terms of Callan-Symanzik beta function and effective coupling constant. The derivatives define the convexity and the extremum of the energy density curve. In the vacuum the energy-momentum tensor is proportional to the space-time metric, and induces a negative contribution to the effective cosmological constant.

    ↳ hep-thhep-phEPJC(2020)·26 citations
18. 18*

    Lattice QCD matrix elements for the $B_s^0-{\bar{B}}_s^0$ width difference beyond leading order

    Christine T. H. Davies🇬🇧 · Judd Harrison🇬🇧 · G. Peter Lepage🇺🇸 · Christopher J. Monahan🇺🇸 · Junko Shigemitsu🇺🇸 · Matthew Wingate🇬🇧

    Predicting the $B_s^0-{\bar{B}}_s^0$ width difference $\Delta {\Gamma }_s$ relies on the heavy quark expansion and on hadronic matrix elements of $\Delta B=2$ operators. We present the first lattice QCD results for matrix elements of the dimension-7 operators $R_{2,3}$ and linear combinations ${\tilde{R}}_{2,3}$ using nonrelativistic QCD for the bottom quark and a highly improved staggered quark (HISQ) action for the strange quark. Computations use MILC ensembles of gauge field configuations with $2+1+1$ flavors of sea quarks with the HISQ discretization, including lattices with physically light up/down quark masses. We discuss features unique to calculating matrix elements of these operators and analyze uncertainties from series truncation, discretization, and quark mass dependence. Finally we report the first Standard Model determination of $\Delta {\Gamma }_s$ using lattice QCD results for all hadronic matrix elements through $\mathcal{O}(1/m_b)$. The main result of our calculations yields the $1/m_b$ contribution $\Delta {\Gamma }_{1/m_b}=-0.022(10){\mathrm{ps}}^{-1}$. Adding this to the leading order contribution, the Standard Model prediction is $\Delta {\Gamma }_s=0.092(14){\mathrm{ps}}^{-1}$.

    ↳ hep-lathep-phPRL(2020)·43 citations
19. 19*

    A model for neutrino-nucleus interactions in the GeV region

    Maria B. Barbaro🇮🇹

    We review the recent progress in modelling neutrino-nucleus scattering, in a framework based on scaling which describes simultaneously the nuclear response to electromagnetic and weak probes. The study is relevant for the analysis of neutrino oscillation data and the design of the next generation experiments Hyper-Kamiokande and DUNE.

    ↳ nucl-thhep-phJ.Phys.Conf.Ser.(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.