Thu·Jan 4, 2018Thursday·January 4, 2018

1. 01*

   Searching for LFV Flavon decays at hadron colliders

   M. Arroyo-Ureña🇲🇽 · A. Bolaños🇲🇽 · J.L. Díaz-Cruz🇲🇽 · G.Hernández-Tomé · G. Tavares-Velasco🇲🇽

   The search for Flavons with a mass of $\mathcal{O}$(1) TeV at current and future colliders might probe low-scale flavor models. We are interested in the simplest model that invokes the Froggatt-Nielsen (FN) mechanism with an Abelian flavor symmetry, which includes a Higgs doublet and a FN complex singlet. Assuming a CP conserving scalar potential, there are a $CP$-even $H_F$ and a $CP$-odd $A_F$ Flavons with lepton flavor violating (LFV) couplings. The former can mix with the standard-model-like Higgs boson, thereby inducing tree-level LFV Higgs interactions that may be at the reach of the LHC. We study the constraints on the parameter space of the model from low-energy LFV processes, which are then used to evaluate the Flavon decay widths and the $gg\to \varphi \to \tau \mu$ ($\varphi =H_F,A_F$) production cross section at hadron colliders. After imposing several kinematic cuts to reduce the SM main background, we find that for $m_{H_F}$ about 200-350 GeV, the decay $H_F\to \tau \mu$ might be at the reach of the LHC for a luminosity in the range 1-3 ab${}^{-1}$, however, a luminosity of the order of 10 ab${}^{-1}$ would be required to detect the $A_F\to \tau \mu$ decay. On the other hand a future 100 TeV $pp$ collider could probe masses as high as $\mathcal{O}$(10) TeV if it reaches an integrated luminosity of at least 20 ab${}^{-1}$. Therefore, the 100 TeV Collider could work as a Flavon factory.

   hep-phPRD(2018)·19 citations
2. 02*

   Parton self-energies for general momentum-space anisotropy

   Babak S. Kasmaei🇺🇸 · Michael Strickland🇺🇸

   We introduce an efficient general method for calculating the self-energies, collective modes, and dispersion relations of quarks and gluons in a momentum-anisotropic high-temperature quark-gluon plasma. The method introduced is applicable to the most general classes of deformed anisotropic momentum distributions and the resulting self-energies are expressed in terms of a series of hypergeometric basis functions which are valid in the entire complex phase-velocity plane. Comparing to direct numerical integration of the self-energies, the proposed method is orders of magnitude faster and provides results with similar or better accuracy. To extend previous studies and demonstrate the application of the proposed method, we present numerical results for the parton self-energies and dispersion relations of partonic collective excitations for the case of an ellipsoidal momentum-space anisotropy. Finally, we also present, for the first time, the gluon unstable mode growth rate for the case of an ellipsoidal momentum-space anisotropy.

   hep-phnucl-thPRD(2018)·16 citations
3. 03*

   Probing the R-parity violating supersymmetric effects in $B_c\to J/\psi {\ell }^{-}{\bar{\nu }}_{\ell },{\eta }_c{\ell }^{-}{\bar{\nu }}_{\ell }$ and ${\Lambda }_b\to {\Lambda }_c{\ell }^{-}{\bar{\nu }}_{\ell }$ decays

   Bin Wei · Jie Zhu · Jin-Huan Shen · Ru-Min Wang · Gong-Ru Lu

   Motivated by recent $R_D$, $R_{D^{\ast }}$ and $R_{J/\psi }$ anomalies in $B\to D{\ell }^{-}{\bar{\nu }}_{\ell }$, $B\to D^{\ast }{\ell }^{-}{\bar{\nu }}_{\ell }$ and $B_c\to J/\psi {\ell }^{-}{\bar{\nu }}_{\ell }$ decays, respectively, we study possible R-parity violating supersymmetric effects in $B_c\to J/\psi {\ell }^{-}{\bar{\nu }}_{\ell },{\eta }_c{\ell }^{-}{\bar{\nu }}_{\ell }$ and ${\Lambda }_b\to {\Lambda }_c{\ell }^{-}{\bar{\nu }}_{\ell }$ decays, which are also induced by $b\to c{\ell }^{-}{\bar{\nu }}_{\ell }$ at quark level. We find that (I) the constrained slepton exchange couplings ${\lambda }_{i33}{\tilde{\lambda }}_{i23}^{\prime \ast }$ involving in $b\to c{\tau }^{-}{\bar{\nu }}_{\tau }$ transition from relevant latest experimental data still have quite large effects on all (differential) branching ratios and the normalized forward-backward asymmetries of the exclusive semileptonic $b\to c{\tau }^{-}{\bar{\nu }}_{\tau }$ decays as well as the ratios of the (differential) branching ratios; (II) after satisfying the data of $R_D$ and $R_{D^{\ast }}$, the upper limit of $R_{J/\psi }$, $R_{{\eta }_c}$ and $R_{{\Lambda }_c}$ could be increased by 10%, 112% and 24%, respectively, from their upper limits of the Standard Model predictions by the ${\lambda }_{i33}{\tilde{\lambda }}_{i23}^{\prime \ast }$ couplings. The results in this work could be used to probe R-parity violating effects and will correlate with searches for direct supersymmetric signals at the running LHCb and the forthcoming Belle-II.

   hep-phhep-exNPB(2018)·34 citations
4. 04*

   Can INO be Sensitive to Flavor-Dependent Long-Range Forces?

   Amina Khatun🇮🇳 · Tarak Thakore🇺🇸 · Sanjib Kumar Agarwalla🇮🇳

   Flavor-dependent long-range leptonic forces mediated by the ultra-light and neutral bosons associated with gauged $L_e-L_{\mu }$ or $L_e-L_{\tau }$ symmetry constitute a minimal extension of the Standard Model. In presence of these new anomaly free abelian symmetries, the SM remains invariant and renormalizable, and can lead to interesting phenomenological consequences. For an example, the electrons inside the Sun can generate a flavor-dependent long-range potential at the Earth surface, which can enhance ${\nu }_{\mu }$ and ${\bar{\nu }}_{\mu }$ survival probabilities over a wide range of energies and baselines in atmospheric neutrino experiments. In this paper, we explore in detail the possible impacts of these long-range flavor-diagonal neutral current interactions due to $L_e-L_{\mu }$ and $L_e-L_{\tau }$ symmetries (one at-a-time) in the context of proposed 50 kt magnetized ICAL detector at INO. Combining the information on muon momentum and hadron energy on an event-by-event basis, ICAL can place stringent constraints on the effective gauge coupling ${\alpha }_{e\mu /e\tau }<1.2\times 10^{-53}$ ($1.75\times 10^{-53}$) at 90$\%$ (3$\sigma$) C.L. with 500 kt$\cdot$yr exposure. The 90$\%$ C.L. limit on ${\alpha }_{e\mu }$ (${\alpha }_{e\tau }$) from ICAL is $\sim 46$ (53) times better than the existing bound from the Super-Kamiokande experiment.

   hep-phhep-exphysics.ins-detJHEP(2018)·21 citations
5. 05*

   Top Quark Pair Production: theory overview

   Andrew S. Papanastasiou🇬🇧

   In this talk we present the current status of the theoretical description of the production of top-quark pairs at the LHC, detailing recent progress for predictions at the stable-top level as well as for predictions that include the decay of the top quarks.

   hep-phhep-ex5 citations
6. 06*

   Constraining new physics in $b\to c\ell \nu$ transitions

   Martin Jung🇩🇪 · David M. Straub🇩🇪

   $B$ decays proceeding via $b\to c\ell \nu$ transitions with $\ell =e$ or $\mu$ are tree-level processes in the Standard Model. They are used to measure the CKM element $V_{cb}$, as such forming an important ingredient in the determination of e.g. the unitarity triangle; hence the question to which extent they can be affected by new physics contributions is important, specifically given the long-standing tension between $V_{cb}$ determinations from inclusive and exclusive decays and the significant hints for lepton flavour universality violation in $b\to c\tau \nu$ and $b\to s\ell \ell$ decays. We perform a comprehensive model-independent analysis of new physics in $b\to c\ell \nu$, considering all combinations of scalar, vector and tensor interactions occuring in single-mediator scenarios. We include for the first time differential distributions of $B\to D^{\ast }\ell \nu$ angular observables for this purpose. We show that these are valuable in constraining non-standard interactions. Specifically, the zero-recoil endpoint of the $B\to D\ell \nu$ spectrum is extremely sensitive to scalar currents, while the maximum-recoil endpoint of the $B\to D^{\ast }\ell \nu$ spectrum with transversely polarized $D^{\ast }$ is extremely sensitive to tensor currents. We also quantify the room for $e$-$\mu$ universality violation in $b\to c\ell \nu$ transitions, predicted by some models suggested to solve the $b\to c\tau \nu$ anomalies, from a global fit to $B\to D\ell \nu$ and $B\to D^{\ast }\ell \nu$ for the first time. Specific new physics models, corresponding to all possible tree-level mediators, are also discussed. As a side effect, we present $V_{cb}$ determinations from exclusive $B$ decays, both with frequentist and Bayesian statistics, leading to compatible results. The entire numerical analysis is based on open source code, allowing it to be easily adapted once new data or new form factors become available.

   hep-phhep-exJHEP(2019)·174 citations
7. 07*

   Dark Matter Interpretation of the Neutron Decay Anomaly

   Bartosz Fornal🇺🇸 · Benjamin Grinstein🇺🇸

   There is a long-standing discrepancy between the neutron lifetime measured in beam and bottle experiments. We propose to explain this anomaly by a dark decay channel for the neutron, involving one or more dark sector particles in the final state. If any of these particles are stable, they can be the dark matter. We construct representative particle physics models consistent with all experimental constraints.

   hep-phnucl-exnucl-thPRL(2018)·266 citations
8. 08*

   Colored Dark Matter

   Valerio De Luca🇮🇹 · Andrea Mitridate🇮🇹 · Michele Redi🇮🇹 · Juri Smirnov🇮🇹 · Alessandro Strumia🇮🇹

   We explore the possibility that Dark Matter is the lightest hadron made of two stable color octet Dirac fermions $\mathcal{Q}$. The cosmological DM abundance is reproduced for $M_{\mathcal{Q}}\approx 12.5$ TeV, compatibly with direct searches (the Rayleigh cross section, suppressed by $1/M_{\mathcal{Q}}^6$, is close to present bounds), indirect searches (enhanced by $\mathcal{Q}\mathcal{Q}+\bar{\mathcal{Q}}\bar{\mathcal{Q}}\to \mathcal{Q}\bar{\mathcal{Q}}+\mathcal{Q}\bar{\mathcal{Q}}$ recombination), and with collider searches (where $\mathcal{Q}$ manifests as tracks, pair produced via QCD). Hybrid hadrons, made of $\mathcal{Q}$ and of SM quarks and gluons, have large QCD cross sections, and do not reach underground detectors. Their cosmological abundance is $10^5$ times smaller than DM, such that their unusual signals seem compatible with bounds. Those in the Earth and stars sank to their centers; the Earth crust and meteorites later accumulate a secondary abundance, although their present abundance depends on nuclear and geological properties that we cannot compute from first principles.

   hep-phastro-ph.COnucl-thPRD(2018)·118 citations
9. 09*

   Higgs Decays to $ZZ$ and $Z\gamma$ in the SMEFT: an NLO analysis

   Sally Dawson🇺🇸 · Pier Paolo Giardino🇺🇸

   We calculate the complete one-loop electroweak corrections to the inclusive $H\to ZZ$ and $H\to Z\gamma$ decays in the dimension-$6$ extension of the Standard Model Effective Field Theory (SMEFT). The corrections to $H\to ZZ$ are computed for on-shell $Z$ bosons and are a precursor to the physical $H\to Zf\overline{f}$ calculation. We present compact numerical formulas for our results and demonstrate that the logarithmic contributions that result from the renormalization group evolution of the SMEFT coefficients are larger than the finite NLO contributions to the decay widths. As a by-product of our calculation, we obtain the first complete result for the finite corrections to $G_{\mu }$ in the SMEFT.

   hep-phPRD(2018)·86 citations
10. 10*

    Factorization Violation and Scale Invariance

    Matthew D. Schwartz🇺🇸 · Kai Yan🇺🇸 · Hua Xing Zhu🇨🇳

    Factorization violating effects in hadron scattering are due mainly to spectator-spectator interactions. While it is known that these interactions cancel in inclusive cross sections, like for the Drell-Yan process, not much is known about for what classes of observables factorization is violated. We show that for pure Glauber ladder graphs, all amplitude-level factorization violating effects completely cancel at cross section level for any single-scale observable (such as hadronic transverse energy or beam thrust). This result disproves previous claims that these pure Glauber graphs are factorization-violating. Our proof exploits scale invariance of two-to-two scattering amplitudes in an essential way. The leading factorization-violating effects therefore come from graphs with at least one soft gluon, involving the Lipatov vertex off of the Glauber ladders. This implies that real soft radiation must be involved in factorization-violation, shedding light on the connection between factorization-violation and the underlying event.

    hep-phPRD(2018)·35 citations
11. 11*

    Alternative $[SU(3){]}^4$ Model of Leptonic Color and Dark Matter

    Corey Kownacki🇺🇸 · Ernest Ma🇺🇸 · Nicholas Pollard🇺🇸 · Oleg Popov🇺🇸 · Mohammadreza Zakeri🇺🇸

    The alternative $[SU(3){]}^4$ model of leptonic color and dark matter is discussed. It unifies at $M_U\sim 10^{14}$ GeV and has the low-energy subgroup $SU(3{)}_q\times SU(2{)}_l\times SU(2{)}_L\times SU(2{)}_R\times U(1{)}_X$ with $(u,h{)}_R$ instead of $(u,d{)}_R$ as doublets under $SU(2{)}_R$. It has the built-in global $U(1)$ dark symmetry which is generalized $B-L$. In analogy to $SU(3{)}_q$ quark triplets, it has $SU(2{)}_l$ hemion doublets which have half-integral charges and are confined by $SU(2{)}_l$ gauge bosons (stickons). In analogy to quarkonia, their vector bound states (hemionia) are uniquely suited for exploration at a future $e^{-}{e}^{+}$ collider.

    hep-phNPB(2018)·13 citations
12. 12*

    Neutron structure function via a maximum entropy analysis

    Chengdong Han🇨🇳 · Rong Wang🇨🇳 · Xurong Chen🇨🇳

    We employ the maximum entropy method to extract the valence quark distributions of the neutron at a low scale, \( Q_0^2 \). At this initial scale, the neutron is defined to contain only three valence quarks, with no contributions from sea quarks or gluons. The distributions of these initial valence quarks are constrained by principles from quark models, quark-hadron duality, and quark confinement. Employing the DGLAP equations supplemented by parton-parton recombination corrections, we derive the neutron structure function \( F_2^{\rm n} \) at higher scales \( Q^2 \). The resulting ratio of the neutron to proton structure functions, $F_2^{\mathrm{n}}$/$F_2^{\mathrm{p}}$, aligns well with the world deep inelastic scattering data at Bjoken variable $x<0.7$, particularly when accounting for uncertainties from model-dependent corrections. Notably, this ratio is in agreement with the JLab MARATHON data after considering the quark-hadron duality assumption, especially in the region of $x\gtrsim 0.7$. Additionally, our findings for $F_2^{\mathrm{n}}$/$F_2^{\mathrm{p}}$ correspond well with the JLab BONuS experimental results after considering the impact of nucleon resonance contamination in the region $x\gtrsim 0.4,0.5,0.6$. We further compare our predictions for $F_2^{\mathrm{n}}$/$F_2^{\mathrm{p}}$ and the \( u/d \) ratios in the limit as \( x \rightarrow 1 \) with existing theoretical calculations. Finally, we observe a minor violation of isospin symmetry between the proton and neutron, evidenced by the differences in valence quark distributions and the first-order moments of these distributions.

    hep-phEur.Phys.J.Plus(2025)·2 citations
13. 13*

    The Maximal-Density Mass Function for Primordial Black Hole Dark Matter

    Benjamin V. Lehmann🇺🇸 · Stefano Profumo🇺🇸 · Jackson Yant🇺🇸

    The advent of gravitational wave astronomy has rekindled interest in primordial black holes (PBH) as a dark matter candidate. As there are many different observational probes of the PBH density across different masses, constraints on PBH models are dependent on the functional form of the PBH mass function. This complicates general statements about the mass functions allowed by current data, and, in particular, about the maximum total density of PBH. Numerical studies suggest that some forms of extended mass functions face tighter constraints than monochromatic mass functions, but they do not preclude the existence of a functional form for which constraints are relaxed. We use analytical arguments to show that the mass function which maximizes the fraction of the matter density in PBH subject to all constraints is a finite linear combination of monochromatic mass functions. We explicitly compute the maximum fraction of dark matter in PBH for different combinations of current constraints, allowing for total freedom of the mass function. Our framework elucidates the dependence of the maximum PBH density on the form of observational constraints, and we discuss the implications of current and future constraints for the viability of the PBH dark matter paradigm.

    ↳ astro-ph.COhep-phJCAP(2018)·46 citations
14. 14*

    First results from the HAYSTAC axion search

    Benjamin M. Brubaker🇺🇸

    The axion is a well-motivated cold dark matter (CDM) candidate first postulated to explain the absence of $CP$ violation in the strong interactions. CDM axions may be detected via their resonant conversion into photons in a "haloscope" detector: a tunable high-$Q$ microwave cavity maintained at cryogenic temperature, immersed a strong magnetic field, and coupled to a low-noise receiver. This dissertation reports on the design, commissioning, and first operation of the Haloscope at Yale Sensitive to Axion CDM (HAYSTAC), a new detector designed to search for CDM axions with masses above $20$ $\mu \mathrm{eV}$. I also describe the analysis procedure developed to derive limits on axion CDM from the first HAYSTAC data run, which excluded axion models with two-photon coupling $g_{a\gamma \gamma }\gtrsim 2\times 10^{-14}$ ${\mathrm{GeV}}^{-1}$, a factor of 2.3 above the benchmark KSVZ model, over the mass range $23.55<m_a<24.0$ $\mu \mathrm{eV}$. This result represents two important achievements. First, it demonstrates cosmologically relevant sensitivity an order of magnitude higher in mass than any existing direct limits. Second, by incorporating a dilution refrigerator and Josephson parametric amplifier, HAYSTAC has demonstrated total noise approaching the standard quantum limit for the first time in a haloscope axion search.

    ↳ astro-ph.COhep-exhep-phphysics.ins-det35 citations
15. 15*

    Towards a relativistic formulation of baryon-baryon interactions in chiral perturbation theory

    Xiu-Lei Ren🇨🇳 · Kai-Wen Li🇨🇳 · Li-Sheng Geng🇨🇳

    In this talk, we report on two recent studies of relativistic nucleon-nucleon and hyperon-nucleon interactions in covariant chiral perturbation theory, where they are constructed up to leading order. The relevant unknown low energy constants are fixed by fitting to the nucleon-nucleon and hyperon-nucleon scattering data. It is shown that these interactions can describe the scattering data with a quality similar to their next-to-leading order non-relativistic counterparts. These studies show that it is technically feasible to construct relativist baryon-baryon interactions, and in addition, after further refinements, these interactions may provide important inputs to {\it ab initio} relativistic nuclear structure and reaction studies and help improve our understanding of low energy strong interactions.

    ↳ nucl-thhep-phNucl.Phys.Rev.(2017)·6 citations
16. 16*

    Fakeons And Lee-Wick Models

    Damiano Anselmi🇮🇹

    The "fakeon" is a fake degree of freedom, i.e. a degree of freedom that does not belong to the physical spectrum, but propagates inside the Feynman diagrams. Fakeons can be used to make higher-derivative theories unitary. Moreover, they help us clarify how the Lee-Wick models work. In this paper we study the fakeon models, that is to say the theories that contain fake and physical degrees of freedom. We formulate them by (nonanalytically) Wick rotating their Euclidean versions. We investigate the properties of arbitrary Feynman diagrams and, among other things, prove that the fakeon models are perturbatively unitary to all orders. If standard power counting constraints are fulfilled, the models are also renormalizable. The S matrix is regionwise analytic. The amplitudes can be continued from the Euclidean region to the other regions by means of an unambiguous, but nonanalytic, operation, called average continuation. We compute the average continuation of typical amplitudes in four, three and two dimensions and show that its predictions agree with those of the nonanalytic Wick rotation. By reconciling renormalizability and unitarity in higher-derivative theories, the fakeon models are good candidates to explain quantum gravity.

    ↳ hep-thhep-phmath-phmath.MPJHEP(2018)·147 citations
17. 17*

    Expectations of the Cosmic Antideuteron Flux

    Su-Jie Lin🇨🇳 · Xiao-Jun Bi🇨🇳 · Peng-Fei Yin🇨🇳

    The cosmic antideuteron is a promising probe for the dark matter annihilation signature. In order to determine the DM signature, the background astrophysical antideuteron flux should be carefully studied. In this work we provide a new calculation of the secondary antideuteron flux, and pay special attention to the uncertainties from hadronic interaction models by using several Monte Carlo generators. The uncertainties from propagation effects are also carefully investigated for both the astrophysical background and DM annihilation signature in several scenarios, which are constrained by the latest B/C ratio measured by AMS-02. Considering these uncertainties, we find that the secondary antideuteron flux is hard to detect in the near future detectors. However, the antideuteron signature from dark matter annihilation will be detectable even considering the constraint from the AMS-02 observation of the $\bar{p}/p$ ratio.

    ↳ astro-ph.HEhep-ph14 citations
18. 18*

    Analytic vortex solutions in generalized models of the Maxwell-Higgs type

    D. Bazeia🇧🇷 · L. Losano🇧🇷 · M.A. Marques🇧🇷 · R. Menezes🇧🇷

    This work deals with the presence of analytical vortex configurations in generalized models of the Maxwell-Higgs type in the three-dimensional spacetime. We implement a procedure that allows to decouple the first order equations, which we use to solve the model analytically. The approach is exemplified with three distinct models that show the robustness of the construction. In the third model, one finds analytical solutions that exhibit interesting compact vortex behavior.

    ↳ hep-thhep-phmath-phmath.MPPLB(2018)·18 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.