Tue·Oct 22, 2019Tuesday·October 22, 2019

1. 01*

   Renormalization and Matching for the Collins-Soper Kernel from Lattice QCD

   Markus A. Ebert🇺🇸 · Iain W. Stewart🇺🇸 · Yong Zhao🇺🇸

   The Collins-Soper kernel, which governs the energy evolution of transverse-momentum dependent parton distribution functions (TMDPDFs), is required to accurately predict Drell-Yan like processes at small transverse momentum, and is a key ingredient for extracting TMDPDFs from experiment. Earlier we proposed a method to calculate this kernel from ratios of the so-called quasi-TMDPDFs determined with lattice QCD, which are defined as hadronic matrix elements of staple-shaped Euclidean Wilson line operators. Here we provide the one-loop renormalization of these operators in a regularization-independent momentum subtraction (RI${}^{\prime }$/MOM) scheme, as well as the conversion factor from the RI${}^{\prime }$/MOM-renormalized quasi-TMDPDF to the $\overline{\mathrm{MS}}$ scheme. We also propose a procedure for calculating the Collins-Soper kernel directly from position space correlators, which simplifies the lattice determination.

   hep-phhep-latnucl-thJHEP(2020)·79 citations
2. 02*

   Enlarging the scope of resonant di-Higgs searches: Hunting for Higgs-to-Higgs cascades in $4b$ final states at the LHC and future colliders

   D. Barducci🇮🇹 · K. Mimasu🇧🇪 · J. M. No🇪🇸 · C. Vernieri🇺🇸 · J. Zurita🇩🇪

   We extend the coverage of resonant di-Higgs searches in the $b\bar{b}b\bar{b}$ final state to the process $pp\to H_1\to H_2{H}_2\to b\bar{b}b\bar{b}$, where both $H_{1,2}$ are spin-$0$ states beyond the Standard Model. Such a process constitutes a joint discovery mode for the new states $H_1$ and $H_2$. We present the first sensitivity study of this channel, using public LHC data to validate our analysis. We also provide a first estimate of the sensitivity of the search for the HL-LHC and future facilities like the HE-LHC and FCC-hh. We analyze the discovery potential of this search for several non-minimal scalar sector scenarios: an extension of the SM with two extra singlet scalar fields, the two-Higgs-doublet model and a two-Higgs doublet model plus a singlet, which captures the scalar potential features of the NMSSM. We find that this channel represents a novel, very powerful probe for extended Higgs sectors, offering complementary sensitivity to existing analyses.

   hep-phhep-exJHEP(2020)·22 citations
3. 03*

   AI Safety for High Energy Physics

   Benjamin Nachman🇺🇸 · Chase Shimmin🇺🇸

   The field of high-energy physics (HEP), along with many scientific disciplines, is currently experiencing a dramatic influx of new methodologies powered by modern machine learning techniques. Over the last few years, a growing body of HEP literature has focused on identifying promising applications of deep learning in particular, and more recently these techniques are starting to be realized in an increasing number of experimental measurements. The overall conclusion from this impressive and extensive set of studies is that rarer and more complex physics signatures can be identified with the new set of powerful tools from deep learning. However, there is an unstudied systematic risk associated with combining the traditional HEP workflow and deep learning with high-dimensional data. In particular, calibrating and validating the response of deep neural networks is in general not experimentally feasible, and therefore current methods may be biased in ways that are not covered by current uncertainty estimates. By borrowing ideas from AI safety, we illustrate these potential issues and propose a method to bound the size of unaccounted for uncertainty. In addition to providing a pragmatic diagnostic, this work will hopefully begin a dialogue within the community about the robust application of deep learning to experimental analyses.

   hep-phcs.LGhep-exstat.ML21 citations
4. 04*

   One-Loop Charge-Breaking Minima in the Two-Higgs Doublet Model

   Pedro M. Ferreira🇵🇹 · Logan A. Morrison🇺🇸 · Stefano Profumo🇺🇸

   We analyze the vacuum structure of the one-loop effective potential in the two Higgs doublet model. We find that electroweak-breaking vacuua can coexist with charge breaking ones, contradicting a theorem valid at tree-level. We perform a numerical analysis of the model and supply explicit parameter values for which charge-breaking vacuua can be the global minimum of the theory, and deeper than charge-preserving ones.

   hep-phJHEP(2020)·9 citations
5. 05*

   Electroweak Quintessence Axion as Dark Energy

   Masahito Yamazaki🇯🇵

   We discuss the electroweak quintessence axion as a candidate for dark energy, taking into account observational as well as quantum-gravity constraints.

   hep-phastro-ph.COhep-th0 citations
6. 06*

   Proton structure and hollowness from Lévy imaging of $pp$ elastic scattering

   T. Csörgő🇭🇺 · R. Pasechnik🇸🇪 · A. Ster🇭🇺

   The recently developed Lévy imaging method enables to extract an important physics information on hadron structure at high energies and ultra-low momentum transfers directly from elastic scattering data. In this work, we employ such a model-independent method to probe the internal structure of the proton and quantify its inelasticity profile in the impact parameter space emerging in proton-proton collisions at the highest available energy of $\sqrt{s}=13$ TeV. The inelasticity profile function and its error band for the proton and its substructure have been reconstructed at different energies and the proton hollowness (or "black-ring") effect with beyond 5$\sigma$ significance has been found at 13 TeV.

   hep-phEPJC(2020)·25 citations
7. 07*

   Trans-Planckian Censorship and Inflation in Grand Unified Theories

   Kai Schmitz🇨🇭

   The recently proposed trans-Planckian censorship conjecture (TCC) amounts to the claim that inflation models with an inflationary energy scale larger than Lambda_inf^max ~ 10^9 GeV belong to the swampland, i.e., cannot be embedded into a consistent theory of quantum gravity. In this paper, we point out that this constraint can be readily satisfied in D-term hybrid inflation (DHI), which is a well-motivated inflation scenario in the context of supersymmetric grand unification. In DHI, the amplitude of the primordial scalar power spectrum originates from a Fayet-Iliopoulos term of the order of the unification scale, sqrt{xi} ~ 10^16 GeV. At the same time, the TCC results in an upper bound on the corresponding gauge coupling constant of g_max ~ 10^-14. We are able to show that this constraint translates into an upper bound on the gravitino mass of m_3/2^max ~ 10 MeV, which opens the possibility that dark matter is accounted for by thermally produced gravitinos, if the reheating temperature is close to T_reh ~ 100 TeV. Interestingly enough, a somewhat similar gravitino mass range has recently been derived in a model that aims at explaining dark energy in terms of axion quintessence and resolving the Hubble tension by means of decaying gravitino dark matter.

   hep-phastro-ph.COhep-thPLB(2020)·32 citations
8. 08*

   Towards Minimal SU(5)

   Ilja Doršner🇭🇷 · Shaikh Saad🇺🇸

   We propose a simple $SU(5)$ model that connects the neutrino mass generation mechanism to the observed disparity between the masses of charged leptons and down-type quarks. The model is built out of $5$-, $10$-, $15$-, $24$-, and $35$-dimensional representations of $SU(5)$ and comprises two (three) $3\times 3$ ($3\times 1$) Yukawa coupling matrices to accommodate all experimentally measured fermion masses and mixing parameters. The gauge coupling unification considerations, coupled with phenomenological constraints inferred from experiments that probe neutrino masses and mixing parameters and/or look for proton decay, fix all relevant mass scales of the model. The proposed scenario places several multiplets at the scales potentially accessible at the LHC and future colliders and correlates this feature with the gauge boson mediated proton decay signatures. It also predicts that one neutrino is massless.

   hep-phPRD(2020)·29 citations
9. 09*

   High Energy Hadron Production, Self-Organized Criticality and Absorbing State Phase Transition

   P.Castorina🇮🇹 · H.Satz🇩🇪

   In high energy nuclear collisions, production rates of light nuclei agree with the predictions of an ideal gas at a temperature $T=155\pm 10$ MeV. In an equilibrium hadronic medium of this temperature, light nuclei cannot survive. In this contribution, we suggest that the observed behavior is due to an evolution in global non-equilibrium, leading to self-organized criticality and to hadron formation as an absorbing state phase transition for color degrees of freedom. At the confinement point, the initial quark-gluon medium becomes quenched by the vacuum, breaking up into all allowed free hadronic and nuclear mass states, without (or with a very short-live) subsequent formation of thermal hadronic medium.

   hep-phnucl-thSpringer Proc.Phys.(2020)·1 citation
10. 10*

    Inverse Mass Hierarchy of Light Scalar Mesons Driven by Anomaly-Induced Flavor Breaking

    Yoshiki Kuroda🇯🇵 · Masayasu Harada🇯🇵 · Shinya Matsuzaki🇨🇳 · Daisuke Jido🇯🇵

    We propose a novel mechanism to reproduce the observed mass hierarchy for the scalar mesons lighter than 1 GeV (called the inverse hierarchy) regarding them as mesons made of a quark and an anti-quark ($q\bar{q}$ mesons). The source is provided by the SU(3)-flavor symmetry-breaking induced by U(1) axial anomaly. In particular, the anomaly term including the explicit-chiral symmetry-breaking plays a significant role for the light scalar meson spectrum. To be concrete, we construct a linear sigma model for the scalar mesons of $q\bar{q}$ type together with their pseudoscalar chiral partners, including an anomaly-induced explicit-chiral symmetry-breaking term. We find that, due to the proposed mechanism, the inverse hierarchy, i.e., $m\left[a_0(980)\right]\simeq m\left[f_0(980)\right]>m\left[K_0^{\ast }(700)\right]>m\left[f_0(500)\right]$ is indeed realized. Consequently, the quark content of $f_0(500)$ is dominated by the isoscalar $\bar{u}u+\bar{d}d$ component, and $f_0(980)$ is by the strange quark bilinear's, $s\bar{s}$.

    hep-phPTEP(2020)·17 citations
11. 11*

    The Selfish Higgs and Reheating

    Hyun Min Lee🇰🇷

    We consider the cosmological relaxation of the Higgs mass and the cosmological constant due to the four-form fluxes in four dimensions. We present a general class of models with a singlet scalar field containing four-form couplings where the Higgs mass is relaxed to a right value and the Universe reheats to a sufficiently high reheating temperature after the last membrane nucleation. We also discuss some of interesting features in the cases of singlet scalar fields with non-minimal or minimal couplings to gravity and show how the new scalar fields can play a role for dark matter production.

    hep-phhep-thJHEP(2020)·7 citations
12. 12*

    Calculation of the $B\to K_{0,2}^{\ast }(1430)f_0(980)/\sigma$ decays in the Perturbative QCD Approach

    Qi-Xin Li🇨🇳 · Lei Yang🇨🇳 · Zhi-Tian Zou🇨🇳 · Ying Li🇨🇳 · Xin Liu🇨🇳

    Motivated by the observations of the decays $B^0\to K_0^{\ast }(1430{)}^0{f}_0(980)$ and $B^0\to K_2^{\ast }(1430{)}^0{f}_0(980)$ from BaBar collaboration, we study the $B^{0(+)}\to K_{0,2}^{\ast }(1430{)}^{0(+)}{f}_0(980)/\sigma$ decays in the perturbative QCD approach for the first time. In the absence of reliable nonperturbative wave functions we only assume the scalar meson $f_0(980)$ and $\sigma$ are two-quark ground states. In our calculations, these decays are all dominated by the hard-scattering emission and annihilation diagrams, while the factorizable emission diagrams are forbidden or suppressed heavily by the vector decay constants. Furthermore, the branching fractions are sensitive to the mixing between $f_0(980)$ and $\sigma$. Comparing our results with the experimental data, a large mixing angle $\theta$ is favored. Taking $\theta =145^{\circ }$, the orders of branching fractions of $B\to K_0^{\ast }(1430{)}^0\sigma$, $B\to K_2^{\ast }(1430{)}^0\sigma$ and $B\to K_{0,2}^{\ast }(1430{)}^0{f}_0(980)$ are predicted to be $10^{-4}$, $10^{-5}$ and $10^{-6}$, respectively, which can be measured in the current experiments such as LHCb and Belle-2. In addition, although these decays are penguin dominant, the mixing also leads to large direct $CP$ asymmetries in these decays. With the precise data in future, our results could shed light on the inner structure of the scalar mesons and can be used to determine the mixing angle of the $\sigma -f_0(980)$ system.

    hep-phhep-exEPJC(2019)·11 citations
13. 13*

    Feasibility study of the $K^{+}d\to K^{0}pp$ reaction for the "${\Theta }^{+}$" pentaquark

    Takayasu Sekihara🇯🇵 · Hyun-Chul Kim🇰🇷 · Atsushi Hosaka🇯🇵

    We investigate theoretically the $K^{0}p$ invariant mass spectrum of the $K^{+}d\to K^{0}pp$ reaction and scrutinize how the signal of the "${\Theta }^{+}$" pentaquark, if it exists, emerges in the $K^{0}p$ spectrum. The most prominent advantage of this reaction is that we can clearly judge whether the "${\Theta }^{+}$" exists or not as a direct-formation production without significant backgrounds, in contrast to other reactions such as photoproduction and $\pi$-induced productions. We show that while the impulse or single-step scattering process can cover the "${\Theta }^{+}$" energy region with an initial kaon momentum $k_{\mathrm{lab}}\approx 0.40\mathrm{GeV}/c$ in the laboratory frame, the contributions from double-step processes may have a potential possibility to reach the "${\Theta }^{+}$" energy region with a higher kaon momentum $k_{\mathrm{lab}}\sim 1\mathrm{GeV}/c$. Assuming that the full decay width of the "${\Theta }^{+}$" is around $0.5\mathrm{MeV}$, we predict that the magnitude of the peak corresponding to the "${\Theta }^{+}$" is around a few hundred $\mu \mathrm{b}$ to $1\mathrm{mb}$ with the momentum of the kaon beam $k_{\mathrm{lab}}\approx 0.40\mathrm{GeV}/c$ while it is around $\lesssim 1\mu \mathrm{b}$ with $k_{\mathrm{lab}}\approx 0.85\mathrm{GeV}/c$. Thus, the "${\Theta }^{+}$" peak is more likely to be seen at $k_{\mathrm{lab}}\approx 0.40\mathrm{GeV}/c$ than at $k_{\mathrm{lab}}\approx 0.85\mathrm{GeV}/c$.

    hep-phhep-exnucl-exnucl-thPTEP(2020)·8 citations
14. 14*

    Investigating the role of new physics in $b\to c\tau {\bar{\nu }}_{\tau }$ transitions

    Suchismita Sahoo🇮🇳 · Rukmani Mohanta🇮🇳

    In recent times, the charged-current mediated semileptonic $b\to c\tau {\bar{\nu }}_{\tau }$ processes have attracted a lot of attention after the observation of lepton non-universality ratios, $R_{D^{(\ast )}}$, $R_{J/\psi }$ and the measurements on $D^{\ast }$ and $\tau$ longitudinal polarization fractions in $\bar{B}\to D^{\ast }\tau {\bar{\nu }}_{\tau }$ processes. We present a model-independent analysis of $\bar{B}\to D^{(\ast )}\tau {\bar{\nu }}_{\tau }$, $B_s\to D_s^{(\ast )}\tau {\bar{\nu }}_{\tau }$, $B_c^{+}\to ({\eta }_c,J/\psi ){\tau }^{+}{\nu }_{\tau }$, ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ and $\bar{B}\to D^{\ast \ast }\tau {\bar{\nu }}_{\tau }$ (where $D^{\ast \ast }=\{D_0^{\ast },D_1^{\ast },D_1,D_2^{\ast }\}$ are the four lightest excited charm mesons) processes involving $b\to c\tau \bar{\nu }$ quark level transitions by considering the most general effective Lagrangian in the presence of new physics. We perform a global fit to various set of new coefficients, including the measurements on $R_{D^{(\ast )}}$, $R_{J/\psi }$ and the upper limit on Br($B_c^{+}\to {\tau }^{+}{\bar{\nu }}_{\tau }$). We then show the implications of constrained new couplings on the branching fractions, lepton non-universality ratios and various angular observables of these decay modes in four different bins of $q^2$.

    hep-ph19 citations
15. 15*

    CP violation in the top-assisted electroweak baryogenesis

    Wei Chao🇨🇳 · Yandong Liu🇨🇳

    The origin of the baryon asymmetry of the universe (BAU) is a longstanding problem in the high energy physics. The electroweak baryogenesis mechanism, which generates the BAU during the first order electroweak phase transition, provides a testable solution to this problem. In this paper we revisit the top-assisted electroweak baryogenesis model, which extends the standard model (SM) with only one scalar singlet. Constraints on the new CP-violating coupling as well as the mixing between the SM Higgs and the new scalar singlet are derived by considering the latest result of ACME and oblique observables. Furthermore, we derive constraints on these two parameters arising from the data of Higgs measurement at the LHC as well as the four top-quark production at the LHC.

    hep-ph5 citations
16. 16*

    The Nature of the Neutrino (Dirac/Majorana) and Double Beta Decay with or without Neutrinos

    S. T. Petcov🇮🇹

    The history of research associated with the fundamental problem of the nature of massive neutrinos, which can be Dirac particles or Majorana fermions, and the related processes of neutrinoless double beta decay, $(A,Z)\to (A,Z+2)+e^{-}+e^{-}$, and two neutrino double beta decay, $(A,Z)\to (A,Z+2)+e^{-}+e^{-}+\overline{{\nu }_e}+\overline{{\nu }_e}$, is reviewed.

    hep-phProceedings of the International Conferen…·7 citations
17. 17*

    Searching for odderon exchange in exclusive $pp\to pp\varphi \varphi$ reaction

    Piotr Lebiedowicz🇵🇱 · Otto Nachtmann🇩🇪 · Antoni Szczurek🇵🇱

    We discuss the possibility to use the $pp\to pp\varphi \varphi$ process in identifying the odderon exchange. So far there is no unambiguous experimental evidence for the odderon, the charge conjugation $C=-1$ counterpart of the $C=+1$ pomeron. Last year results of the TOTEM collaboration suggest that the odderon exchange can be responsible for a disagreement of theoretical calculations and the TOTEM data for elastic proton-proton scattering. Here we present recent studies for central exclusive production (CEP) of $\varphi \varphi$ pairs in proton-proton collisions. We consider the pomeron-pomeron fusion to $\varphi \varphi$ ($\mathbb{PP}\to \varphi \varphi$) through the continuum processes, due to the $\hat{t}$- and $\hat{u}$-channel reggeized $\varphi$-meson, photon, and odderon exchanges, as well as through the $s$-channel resonance process ($\mathbb{PP}\to f_2(2340)\to \varphi \varphi$). This $f_2$ state is a candidate for a tensor glueball. The amplitudes for the processes are formulated within the tensor-pomeron and vector-odderon approach. Some model parameters are determined from the comparison to the WA102 experimental data. The odderon exchange is not excluded by the WA102 data for high $\varphi \varphi$ invariant masses. The measurement of large $M_{\varphi \varphi }$ or ${\mathrm{Y}}_{\mathrm{diff}}$ events at the LHC would therefore suggest presence of the odderon exchange.

    hep-phPoS(2020)·0 citations
18. 18*

    Two-Loop QCD Corrections to the Higgs plus three-parton amplitudes with Top Mass Correction

    Qingjun Jin🇨🇳 · Gang Yang🇨🇳

    We obtain the two-loop QCD corrections to the Higgs plus three-parton amplitudes with dimension-seven operators in Higgs effective field theory. This provides the two-loop S-matrix elements for Higgs plus one-jet production at the LHC with top-mass correction. We apply efficient unitarity plus IBP methods which are described in detail. We also study the color decomposition of the fermion cuts and find a connection between fundamental and adjoint representations which can be used to reduce non-planar to planar unitarity cuts in the Higgs to three-gluon amplitudes. We obtain final results in simple analytic form which exhibits intriguing hidden structures. The principle of maximal transcendentality is found to be satisfied for all results. The lower transcendentality parts also contain universal building blocks and can be written in compact analytic form, suggesting further hidden structures.

    hep-phhep-thJHEP(2020)·15 citations
19. 19*

    Probing the trilinear Higgs boson self-coupling via single Higgs production at the LHeC

    Ruibo Li🇨🇳 · Xiao-Min Shen🇨🇳 · Bo-Wen Wang🇨🇳 · Kai Wang🇨🇳 · Guohuai Zhu🇨🇳

    The determination of the Higgs self coupling is one of the key ingredients for understanding the mechanism behind the electroweak symmetry breaking. An indirect method for constraining the Higgs trilinear self coupling via single Higgs production at next-to-leading order (NLO) has been proposed in order to avoid the drawbacks of studies with double Higgs production. In this paper we study the Higgs self interaction through the vector boson fusion (VBF) process $e^{-}p\to {\nu }_{e}hj$ at the future LHeC. At NLO level, we compute analytically the scattering amplitudes for relevant processes, in particular those induced by the Higgs self interaction. A Monte Carlo simulation and a statistical analysis utilizing the analytic results are then carried out for Higgs production through VBF and decay to $b\bar{b}$, which yield for the trilinear Higgs self-coupling rescaling parameter ${\kappa }_{\lambda }$ the limit [-0.57, 2.98] with $2{\text{ab}}^{-1}$ integrated luminosity. If we assume about 10% of the signal survives the event selection cuts, and include all the background, the constraint will be broadened to [-2.11, 4.63].

    hep-phPRD(2020)·9 citations
20. 20*

    Probing quadruplet scalar dark matter at current and future $pp$ colliders

    Yu-Pan Zeng🇨🇳 · Chengfeng Cai🇨🇳 · Dan-Yang Liu🇨🇳 · Zhao-Huan Yu🇨🇳 · Hong-Hao Zhang🇨🇳

    We investigate a dark matter model involving an inert $\mathrm{SU}(2{)}_{\mathrm{L}}$ quadruplet scalar with hypercharge 1/2. After the electroweak symmetry breaking, the dark sector contains one doubly charged, two singly charged, and two neutral scalars. The lighter neutral scalar can be a viable dark matter candidate. Electroweak production of these scalars at the Large Hadron Collider leads to potential signals in the $\text{monojet}+/E_{\mathrm{T}}$ and $\text{soft-leptons}+\text{jets}+/E_{\mathrm{T}}$ channels. We thus derive constraints on the model by reinterpreting recent experimental searches. Based on simulation, we further evaluate the sensitivity at a future 100 TeV $pp$ collider.

    hep-phPRD(2020)·7 citations
21. 21*

    The Minimal Seesaw Model with a Modular $S_4$ Symmetry

    Xin Wang🇨🇳 · Shun Zhou🇨🇳

    In this paper, we incorporate the modular $S_4^{}$ flavor symmetry into the supersymmetric version of the minimal type-I seesaw model, in which only two right-handed neutrino singlets are introduced to account for tiny Majorana neutrino masses, and explore its implications for the lepton mass spectra, flavor mixing and CP violation. The basic idea is to assign two right-handed neutrino singlets into the unique two-dimensional irreducible representation of the modular $S_4^{}$ symmetry group. Moreover, we show that the matter-antimatter asymmetry in our Universe can be successfully explained via the resonant leptogenesis mechanism working at a relatively-low seesaw scale ${\Lambda }_{\mathrm{SS}}^{}\approx 10^7\mathrm{GeV}$, with which the potential problem of the gravitino overproduction can be avoided. In this connection, we emphasize that the observed matter-antimatter asymmetry may lead to a stringent constraint on the parameter space and testable predictions for low-energy observables.

    hep-phJHEP(2020)·118 citations
22. 22*

    Glauber Monte Carlo predictions for ultra-relativistic collisions with ${}^{16}\mathrm{O}$

    Maciej Rybczyński🇵🇱 · Wojciech Broniowski🇵🇱

    We explore Glauber Monte Carlo predictions for the planned ultra-relativistic ${}^{16}\mathrm{O}$+${}^{16}\mathrm{O}$ and p+${}^{16}\mathrm{O}$ collisions, as well as for collisions of ${}^{16}\mathrm{O}$ on heavy targets. In particular, we present specific collective flow measures which are approximately independent on the hydrodynamic response of the system, such as the ratios of eccentricities obtained from cumulants with different numbers of particles, or correlations of ellipticity and triangularity described by the normalized symmetric cumulants. We use the state-of-the-art correlated nuclear distributions for ${}^{16}\mathrm{O}$ and compare the results to the uncorrelated case, finding moderate effects for the most central collisions. We also consider the wounded quark model, which turns out to yield similar results to the wounded nucleon model for the considered measures. The purpose of our study is to prepare some ground for the upcoming experimental proposals, as well as to provide input for possible more detailed dynamical studies with hydrodynamics or transport codes.

    hep-phnucl-thPRC(2019)·50 citations
23. 23*

    Minimal Realizations of Dirac Neutrino Mass from Generic One-loop and Two-loop Topologies at $d=5$

    Sudip Jana🇩🇪 · Vishnu P.K.🇺🇸 · Shaikh Saad🇺🇸

    We carry out a systematic investigation for the minimal Dirac neutrino mass models emerging from generic one-loop and two-loop topologies that arise from $d=5$ effective operator with a singlet scalar, $\sigma$. To ensure that the tree-level Dirac mass, as well as Majorana mass terms at all orders, are absent for the neutrinos, we work in the framework where the Standard Model is supplemented by the well-motivated $U(1{)}_{B-L}$ gauge symmetry. At the one-loop level, we analyze six possible topologies, out of which two of them have the potential to generate desired Dirac neutrino mass. Adopting a systematic approach to select minimal models, we construct seventeen viable one-loop Dirac neutrino mass models. By embracing a similar methodical approach at the two-loop, we work out twenty-three minimal candidates. Among the forty selected economical models, the majority of the models proposed in this work are new. In our search, we also include the scenarios where the particles in the loop carry charges under the color group. Furthermore, we discuss the possible dark matter candidates within a given model, if any, without extending the minimal particle content.

    hep-phhep-thJCAP(2020)·56 citations
24. 24*

    Anapole Moment of Leptons in the Minimal Supersymmetric Standard Model

    C. Aydın🇹🇷

    Using Feynman-'t Hooft gauge and dimensional regularization, the static parity-violating coupling of the neutrinos and charged leptons to an external electromagnetic field is calculated in the minimal supersymmetry standard model (MSSM). From the obtained result of calculations, we have seen that the main contribution come from chargino particles in MSSM.

    hep-ph2 citations
25. 25*

    Solitosynthesis and Gravitational Waves

    Djuna Croon🇨🇦 · Alexander Kusenko🇺🇸 · Anupam Mazumdar🇳🇱 · Graham White🇨🇦

    We study the gravitational wave phenomenology in models of solitosynthesis. In such models, a first order phase transition is precipitated by a period in which non-topological solitons with a conserved global charge (Q-balls) accumulate charge. As such, the nucleation rate of critical bubbles differs significantly from thermal phase transitions. In general we find that the peak amplitude of the gravitational wave spectrum resulting from solitosynthesis is stronger than that of a thermal phase transition and the timescale of the onset of nonlinear plasma dynamics is comparable to Hubble. We demonstrate this explicitly in an asymmetric dark matter model, and discuss current and future constraints in this scenario.

    hep-phastro-ph.COPRD(2020)·50 citations
26. 26*

    Testing thermal photon and dilepton rates

    G. Jackson🇨🇭 · M. Laine🇨🇭

    We confront the thermal NLO vector spectral function (both the transverse and longitudinal channel with respect to spatial momentum, both above and below the light cone) with continuum-extrapolated lattice data (both quenched and with $N_{\mathrm{f}}=2$, at $T\sim 1.2T_{\mathrm{c}}$). The perturbative side incorporates new results, whose main features are summarized. The resolution of the lattice data is good enough to constrain the scale choice of ${\alpha }_{\mathrm{s}}$ on the perturbative side. The comparison supports the previous indication that the true spectral function falls below the resummed NLO one in a substantial frequency domain. Our results may help to scrutinize direct spectral reconstruction attempts from lattice QCD.

    hep-phhep-latJHEP(2019)·41 citations
27. 27*

    Neutron spin dynamics in polarized targets

    Vladimir Gudkov🇺🇸 · Hirohiko M. Shimizu🇯🇵

    We present neutron elastic scattering amplitude for arbitrary polarized target in irreducible spherical tensor representation. The general approach for the description of neutron spin dynamics for the propagation trough the medium with an arbitrary polarization is discussed in a relation to the search for time reversal invariance violation in neutron scattering.

    ↳ nucl-thhep-phPRC(2020)·10 citations
28. 28*

    A lattice model of heavy-light three-body system

    Peng Guo🇺🇸 · Michael Döring🇺🇸

    We present a study of a $1+1$ dimensional heavy-light three-body system in finite volume. The heavy-light system is simulated by a coupled-channel ${\varphi }^4$ type lattice model, and both ground state and excited states of multiparticle energy spectra are measured on various lattices. The lattice simulation data analysis is performed based on variational approach.

    ↳ hep-lathep-phPRD(2020)·32 citations
29. 29*

    Study of charmonium production using decays to hadronic final states with the LHCb experiment

    Andrii Usachov🇫🇷

    Studies of charmonium properties and production mechanism started with the discovery of $J/\psi$ meson. Since more than 40 years the charmonium production mechanism is still not entirely understood. Following the era of investigations at $e^{+}{e}^{-}$ machines, nowadays, charmonium states are copiously produced at hadron colliders, that allows systematic studies of their resonance parameters, production observables and decays. Despite large production rates, many charmonium states are barely studied due to the complications of their reconstruction against a large background level. The LHCb experiment provides a unique opportunity to study S-wave and P-wave charmonium states using their decays to hadrons. This allows measuring production observables of ${\eta }_c$ and ${\chi }_c$ charmonium states. According to the theoretical formalism of Non-Relativistic QCD (NRQCD), the production observables of the same wave charmonium states are linked. Hence, the LHCb measurements provide a series of stringent tests of NRQCD. In the framework of this thesis, the first measurement of the ${\eta }_c(1S)$ differential production cross-section at $\sqrt{s}=13TeV$ and the most precise to date single mass measurement are performed, where the ${\eta }_c(1S)$ state is reconstructed via its decay to $p\bar{p}$. In addition, the production of the ${\chi }_c$ and ${\eta }_c(2S)$ states in $b$-hadron decays is studied using decays to $\varphi \varphi$. The obtained results are confronted with existing theory predictions. The original phenomenological analysis concludes that the description of charmonium prompt production and production in inclusive $b$-hadron decays in an entire range of transverse momentum remains a challenge.

    ↳ hep-exhep-ph5 citations
30. 30*

    Novel Screening with Two Bodies: Summing the ladder in disformal scalar-tensor theories

    Anne-Christine Davis🇬🇧 · Scott Melville🇬🇧

    When augmenting our cosmological models or gravitational theories with an additional light scalar field, any coupling between matter and this scalar can affect the orbital motion of binary systems. Ordinarily, the new force mediated by the scalar can be naturally the same order of magnitude as the usual gravitational force and therefore is tightly constrained. We show that a disformal coupling between the scalar and matter can lead to a novel screening mechanism in which these fifth forces are suppressed by several orders of magnitude at sufficiently small separations and large relative velocities (such as solar system scales). This is a result of resumming a class of ladder diagrams, which suppresses the propagation of scalar signals between the two bodies. Moreover, we are able to relate potential ambiguities in this resummation to non-perturbative effects (which are invisible to perturbation theory). As a result, solar system tests and future gravitational wave observations can now be used to place meaningful constraints on scalar-tensor theories with disformal couplings. We exemplify this using observational bounds on the precession of planetary orbits.

    ↳ gr-qcastro-ph.COhep-phJCAP(2020)·12 citations
31. 31*

    Multivariate analysis of BATSE gamma-ray burst properties using skewed distributions

    Mariusz Tarnopolski🇵🇱

    The number of classes of gamma-ray bursts (GRBs), besides the well-established short and long ones, remains a debatable issue. It was already shown, however, that when invoking skewed distributions, the $\log T_{90}$ and $\log T_{90}-\log H_{32}$ spaces are adequately modeled with mixtures of only two such components, implying two GRB types. Herein, a comprehensive multivariate analysis of several multi-dimensional parameter spaces is conducted for the BATSE sample of GRBs, with the usage of skewed distributions. It is found that the number of extracted components varies between the examined parameter sets, and ranges from 2 to 4, with higher-dimensional spaces allowing for more classes. A Monte Carlo testing implies that these additional components are likely to be artifacts owing to the finiteness of the data and be a result of examining a particular realization of the data as a random sample, resulting in spurious identifications.

    ↳ astro-ph.HEhep-ph14 citations
32. 32*

    Neutrinos from the gamma-ray source eHWC J1825-134: predictions for Km${}^3$ detectors

    V. Niro🇫🇷 · A. Neronov🇫🇷 · L. Fusco🇫🇷 · S. Gabici🇫🇷 · D. Semikoz🇫🇷

    The eHWC J1825-134 source is located in the southern sky and has been recently detected by the HAWC observatory. It presents an hard spectral index and its gamma-ray flux extends up to energies close to 100 TeV without significant suppression. Amongst the HAWC sources, it is the most luminous in the multi-TeV domain and therefore is one of the first that should be searched for with a neutrino telescope in the northern hemisphere. Using an updated effective area for the forthcoming KM3NeT detector, we study the possibility to detect this source within ten years of its running time. We conclude that about a 4 to 5 sigma detection has to be expected after ten years of observations, depending on the details of the considered scenario.

    ↳ astro-ph.HEhep-phPRD(2021)·13 citations
33. 33*

    Bruno Touschek in Germany after the War: 1945-46

    Luisa Bonolis🇩🇪 · Giulia Pancheri🇮🇹

    Bruno Touschek was an Austrian born theoretical physicist, who proposed and built the first electron-positron collider in 1960 in the Frascati National Laboratories in Italy. In this note we reconstruct a crucial period of Bruno Touschek's life so far scarcely explored, which runs from Summer 1945 to the end of 1946. We shall describe his university studies in Göttingen, placing them in the context of the reconstruction of German science after 1945. The influence of Werner Heisenberg and other prominent German physicists will be highlighted. In parallel, we shall show how the decisions of the Allied powers towards restructuring science and technology in the UK after the war effort, determined Touschek's move to the University of Glasgow in 1947.

    ↳ physics.hist-phhep-phphysics.acc-ph5 citations
34. 34*

    Log-dependent slope of scalar induced gravitational waves in the infrared regions

    Chen Yuan🇨🇳 · Zu-Cheng Chen🇨🇳 · Qing-Guo Huang🇨🇳

    We analytically calculate the scalar induced gravitational waves (SIGWs) and find a log-dependent slope of SIGW in the infrared regions $(f<f_c)$, namely $n_{\mathrm{GW}}(f)=3-2/\ln (f_c/f)$, and $n_{\mathrm{GW}}(f)=2-2/\ln (f_c/f)$ near the peak if the power spectrum of scalar curvature perturbation is quite narrow, where $f_c$ is roughly the frequency at the peak of SIGW. Such a log-dependent slope can be taken as a new template for distinguishing SIGW from other sources.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2020)·129 citations
35. 35*

    Charge and isospin fluctuations in a non-ideal pion gas with dynamically fixed particle number

    E.E. Kolomeitsev🇸🇰 · D.N. Voskresensky🇷🇺 · M.E. Borisov🇷🇺

    We study the behavior of the non-ideal pion gas with the dynamically fixed number of particles, formed on an intermediate stage in ultra-relativistic heavy-ion collisions. The pion spectrum is calculated within the self-consistent Hartree approximation. General expressions are derived for cross-covariances of the number of various particle species in the pion gas of an arbitrary isospin composition. The behavior of the cross-variances is analyzed for the temperature approaching from above the maximal critical temperature of the Bose-Einstein condensation for the pion species $a=\pm ,0$, i.e. for $T>\max T_{\mathrm{cr}}^a$. It is shown that in case of the system with equal averaged numbers of isospin species, the variance of the charge, $Q=N_{+}-N_{-}$, diverges at $T\to T_{\mathrm{cr}}=T_{\mathrm{cr}}^a$, whereas variances of the total particle number, $N=N_{+}+N_{-}+N_0$, and of a relative abundance of charged and neutral pions, $G=(N_{+}+N_{-})/2-N_0$, remain finite in the critical point. Then fluctuations are studied in the pion gas with small isospin imbalance $0<|G|\ll N$ and $0<|Q|\ll N$\, and shifts of the effective masses, chemical potentials and values of critical temperatures are calculated for various pion species, and the highest critical temperature, $\text{mbox}max{T}_{\mathrm{cr}}^a$ is found, above which the pion system exists in the non-condensed phase. Various pion cross variances are calculated for $T>\text{mbox}max{T}_{\mathrm{cr}}^a$, which prove to be strongly dependent on the isospin composition of the system, whereas the variances of $N$ and $G$ are found to be independent on the isospin imbalance up to the term linear in $G/N$ and $Q/N$.

    ↳ nucl-thhep-phEPJA(2021)·6 citations
36. 36*

    Post-Minkowskian Scattering Angle in Einstein Gravity

    N. E. J. Bjerrum-Bohr🇩🇰 · Andrea Cristofoli🇩🇰 · Poul H. Damgaard🇩🇰

    Using the implicit function theorem we demonstrate that solutions to the classical part of the relativistic Lippmann-Schwinger equation are in one-to-one correspondence with those of the energy equation of a relativistic two-body system. A corollary is that the scattering angle can be computed from the amplitude itself, without having to introduce a potential. All results are universal and provide for the case of general relativity a very simple formula for the scattering angle in terms of the classical part of the amplitude, to any order in the post-Minkowskian expansion.

    ↳ hep-thgr-qchep-phJHEP(2020)·181 citations
37. 37*

    Perturbing the ground state of Dirac stars

    Emanuel Daka🇺🇸 · Nhon N. Phan🇺🇸 · Ben Kain🇺🇸

    Dirac stars are self-gravitating configurations of spin-1/2 fermions in which the fermions are described by the Dirac equation. After a detailed review of the derivation of the equations and their static solutions, we present an in-depth dynamical stability analysis of the ground state similar to previous studies for boson stars. We confirm that there exist both stable and unstable branches of static solutions and show that weakly perturbed Dirac stars from the unstable branch migrate to the stable branch. We also show that strongly perturbed Dirac stars from the stable branch migrate to the stable branch if their mass is below a critical value. If their mass is above the critical value they can migrate to the stable branch or collapse and form a black hole. For strongly perturbed Dirac stars from the unstable branch we show that the addition of even a small amount of mass leads to collapse, while if we decrease their mass they migrate to the stable branch.

    ↳ gr-qchep-phPRD(2019)·15 citations
38. 38*

    Trans-Planckian censorship and single-field inflaton potential

    Kenji Kadota🇰🇷 · Chang Sub Shin🇰🇷 · Takahiro Terada🇰🇷 · Gansukh Tumurtushaa🇰🇷

    It was recently proposed that a field theory cannot be consistent with quantum gravity if it allows a mode shorter than the Planck length to exit the Hubble horizon. This is called the Trans-Planckian Censorship Conjecture (TCC). We discuss the implications of the TCC on the possible shape of the inflaton potential in single-field slow-roll inflation. We point out that (1) there is generically an initial condition in which the total e-folding number $N_{\text{total}}$ is doubled or more compared to the e-folds necessary for the cosmic microwave background fluctuations, and (2) a sizable negative running of spectral index is generically expected to make $N_{\text{total}}$ small. In concrete setups, we find a stringent constraint on the inflationary energy scale, $V_{\text{inf}}^{1/4}<\mathcal{O}(10)\text{TeV}$ with $r<\mathcal{O}(10^{-50})$, and the running parameter is bounded above as ${\alpha }_{\text{s}}\lesssim -4\times 10^{-3}$.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2020)·38 citations
39. 39*

    Gravitational wave signatures of ultralight vector bosons from black hole superradiance

    Nils Siemonsen🇨🇭 · William E. East🇨🇦

    In the presence of an ultralight bosonic field, spinning black holes are unstable to superradiance. The rotational energy of the black hole is converted into a non-axisymmetric, oscillating boson cloud which dissipates through the emission of nearly monochromatic gravitational radiation. Thus, gravitational wave observations by ground- or space-based detectors can be used to probe the existence of dark particles weakly coupled to the Standard Model. In this work, we focus on massive vector bosons, which grow much faster through superradiance, and produce significantly stronger gravitational waves compared to the scalar case. We use techniques from black hole perturbation theory to compute the relativistically-correct gravitational wave signal across the parameter space of different boson masses and black hole masses and spins. This fills in a gap in the literature between flatspace approximations, which underestimate the gravitational wave amplitude in the non-relativistic limit, and overestimate it in the relativistic regime, and time-domain calculations, which have only covered a limited part of the parameter space. We also identify parameter ranges where overtone superradiantly unstable modes will grow faster than the lower frequency fundamental modes. Such cases will produce a distinct gravitational wave signal due to the beating of the simultaneously populated modes, which we compute.

    ↳ gr-qcastro-ph.HEhep-phPRD(2020)·124 citations
40. 40*

    The hadronic contribution to the running of the electromagnetic coupling and the electroweak mixing angle

    Marco Cè🇩🇪 · Teseo San José🇩🇪 · Antoine Gérardin🇩🇪 · Harvey B. Meyer🇩🇪 · Kohtaroh Miura🇩🇪 · Konstantin Ottnad🇩🇪 · Andreas Risch🇩🇪 · Jonas Wilhelm🇩🇪 · Hartmut Wittig🇩🇪

    The electromagnetic coupling $\alpha$ and the electroweak mixing angle ${\theta }_{\mathrm{W}}$ are parameters of the Standard Model (SM) that enter precision SM tests and play a fundamental rôle in beyond SM physics searches. Their values are energy dependent, and non-perturbative hadronic contributions are the main source of uncertainty to the theoretical knowledge of the running with energy. We present a lattice study of the leading hadronic contribution to the running of $\alpha$ and ${\sin }^2{\theta }_{\mathrm{W}}$. The former is related to the hadronic vacuum polarization (HVP) function of electromagnetic currents, and the latter to the HVP mixing of the electromagnetic current with the vector part of the weak neutral currents. We use the time-momentum representation (TMR) method to compute the HVP on the lattice, estimating both connected and disconnected contributions on $N_{\mathrm{f}}=2+1$ non-perturbatively $O(a)$-improved Wilson fermions ensembles from the Coordinated Lattice Simulations (CLS) initiative. The use of different lattice spacings and quark masses allows us to reliably extrapolate the results to the physical point.

    ↳ hep-lathep-phPoS(2019)·9 citations
41. 41*

    Exact $\beta$-function of Yang-Mills theory in 2+1 dimensions

    Paul Romatschke🇺🇸

    To set the stage, I discuss the $\beta$-function of the massless O(N) model in three dimensions, which can be calculated exactly in the large N limit. Then, I consider SU(N) Yang-Mills theory in 2+1 space-time dimensions. Relating the $\beta$-function to the expectation value of the action in lattice gauge theory, and the latter to the trace of the energy-momentum tensor, I show that $\frac{d\ln g^2/\mu }{d\ln \mu }=-1$ for all $g$ and all N in one particular renormalization scheme. As a consequence, I find that the Yang-Mills $\beta$-function in three dimensions must have the same sign for all finite and positive bare coupling parameters in any renormalization scheme, and all non-trivial infrared fixed points are unreachable in practice.

    ↳ hep-lathep-phhep-thJHEP(2020)·3 citations
42. 42*

    Gravitational waves and higher dimensions: Love numbers and Kaluza-Klein excitations

    Vitor Cardoso🇵🇹 · Leonardo Gualtieri🇮🇹 · Christopher J. Moore🇬🇧

    Gravitational-wave (GW) observations provide a wealth of information on the nature and properties of black holes. Among these, tidal Love numbers or the multipole moments of the inspiralling and final objects are key to a number of constraints. Here, we consider these observations in the context of higher-dimensional scenarios, with flat large extra dimensions. We show that -- as might be anticipated, but not always appreciated in the literature -- physically motivated set-ups are unconstrained by gravitational-wave data. Dynamical processes that do not excite the Kaluza-Klein (KK) modes lead to a signal identical to that in four-dimensional general relativity in vacuum . In addition, any possible excitation of the KK modes is highly suppressed relative to the dominant quadrupolar term; given existing constraints on the extra dimensions and the masses of the objects seen in gravitational-wave observations, KK modes appear at post-Newtonian order $\sim 10^{11}$. Finally, we re-compute the tidal Love numbers of spherical black holes in higher dimensions. We confirm that these are different from zero, but comparing with previous computations we find a different magnitude and sign.

    ↳ gr-qcastro-ph.HEhep-phhep-thPRD(2019)·79 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.