Mon·Mar 19, 2018Monday·March 19, 2018

1. 01*

   B Anomalies and Leptoquarks at the LHC: Beyond the Lepton-Quark Final State

   Angelo Monteux🇺🇸 · Arvind Rajaraman🇺🇸

   Leptoquarks provide some of the simplest explanations to the hints of lepton flavor non-universality in $B$ decays. In particular, a new confining gauge group can provide a natural and appealing origin for the leptoquarks. So far, direct collider searches have been based on two body decays, namely to a quark and a lepton. We study how composite dynamics can give rise to additional states resulting in modified collider signatures of leptoquarks, as well as new production modes in cascade decays of heavier states. Instead of the standard signature, each leptoquark can result in as many as four jets and a lepton. We reinterpret relevant ATLAS and CMS searches to set limits on this scenario, show how this can relax the current bounds, and propose ways to better constrain this class of models in the future. For example, we show that a leptoquark related to the $R_{D^{(\ast )}}$ anomaly could still be as light as 500 GeV.

   hep-phPRD(2018)·17 citations
2. 02*

   Khuri-Treiman equations for $\pi \pi$ scattering

   JPAC Collaboration: M. Albaladejo🇪🇸 · N. Sherrill🇺🇸 · C. Fernandez-Ramirez🇲🇽 · A. Jackura🇺🇸 · V. Mathieu🇺🇸 · M. Mikhasenko🇩🇪 · J. Nys🇧🇪 · A. Pilloni🇺🇸 · A. P.Szczepaniak🇺🇸

   The Khuri-Treiman formalism models the partial-wave expansion of a scattering amplitude as a sum of three individual truncated series, capturing the low-energy dynamics of the direct and cross channels. We cast this formalism into dispersive equations to study $\pi \pi$ scattering, and compare their expressions and numerical output to the Roy and GKPY equations. We prove that the Khuri-Treiman equations and Roy equations coincide when both are truncated to include only $S$- and $P$-waves. When higher partial waves are included, we find an excellent agreement between the Khuri-Treiman and the GKPY results. This lends credence to the notion that the Khuri-Treiman formalism is a reliable low-energy tool for studying hadronic reaction amplitudes.

   hep-phEPJC(2018)·25 citations
3. 03*

   Few-body quark dynamics for doubly-heavy baryons and tetraquarks

   Jean-Marc Richard (Lyon)🇫🇷 · Alfredo Valcarce (Salamanca)🇪🇸 · Javier Vijande (Valencia)🇪🇸

   We discuss the adequate treatment of the 3- and 4-body dynamics for the quark model picture of double-charm baryons and tetraquarks. We stress that the variational and Born-Oppenheimer approximations give energies very close to the exact ones, while the diquark approximation might be rather misleading. The Hall-Post inequalities also provide very useful lower bounds that exclude the possibility of stable tetraquarks for some mass ratios and some color wave functions.

   hep-phnucl-thPRC(2018)·90 citations
4. 04*

   On the use of the KMR unintegrated parton distribution functions

   Krzysztof Golec-Biernat🇵🇱 · Anna M. Stasto🇺🇸

   We discuss the unintegrated parton distribution functions (UPDFs) introduced by Kimber, Martin and Ryskin (KMR), which are frequently used in phenomenological analyses of hard processes with transverse momenta of partons taken into account. We demonstrate numerically that the commonly used differential definition of the UPDFs leads to erroneous results for large transverse momenta. We identify the reason for that, being the use of the ordinary PDFs instead of the cutoff dependent distribution functions. We show that in phenomenological applications, the integral definition of the UPDFs with the ordinary PDFs can be used.

   hep-phPLB(2018)·42 citations
5. 05*

   On the MSW neutrino mixing effects in atomic weak interactions and double beta decays

   Mihai Horoi🇺🇸

   Matter effects on the mixing of the neutrinos mass eigenstates, also know as the Mikheyev-Smirnov-Wolfenstein effect, seem to be well established in describing the propagation of the neutrino from the source to detecting devices. These effects were mostly considered in bulk matter, but not inside the atoms. Here we consider the effect of the high electron densities existing in the atomic nuclei. We investigate if these effects can affect the known neutrino phenomenology. It was reported that the mixing of the neutrino in high density matter, such as inside a supernova, can affect the Majoron decay probabilities. We investigate if the neutrino mixing effects in the high electron density inside the atomic nuclei can change the neutrinoless double beta decay half-life formula. In both cases we found that the standard results stand. The results look simple, but the road to them is complex and it opens the possibility that the neutrino mixing in atomic nuclei may affect other observables, such as the neutrinoless double beta Majoron decays.

   hep-phnucl-thEPJA(2020)·3 citations
6. 06*

   Electroweak Gauge Boson Parton Distribution Functions

   Bartosz Fornal🇺🇸 · Aneesh V. Manohar🇺🇸 · Wouter J. Waalewijn🇳🇱

   Transverse and longitudinal electroweak gauge boson parton distribution functions (PDFs) are computed in terms of deep-inelastic scattering structure functions, following the recently developed method to determine the photon PDF. The calculation provides initial conditions at the electroweak scale for PDF evolution to higher energies. Numerical results for the $W^{\pm }$ and $Z$ transverse, longitudinal and polarized PDFs, as well as the $\gamma Z$ transverse and polarized PDFs are presented.

   hep-phJHEP(2018)·57 citations
7. 07*

   Loop Induced Single Top Partner Production and Decay at the LHC

   Jeong Han Kim🇺🇸 · Ian M. Lewis🇺🇸

   Most searches for top partners, $T$, are concerned with top partner pair production. However, as these bounds become increasingly stringent, the LHC energy will saturate and single top partner production will become more important. In this paper we study the novel signature of the top partner produced in association with the SM top, $pp\to T\overline{t}+t\overline{T}$, in a model where the Standard Model (SM) is extended by a vector-like $SU(2{)}_L$ singlet fermion top partner and a real, SM gauge singlet scalar, $S$. In this model, $pp\to T\overline{t}+t\overline{T}$ production is possible through loops mediated by the scalar singlet. We find that, with reasonable coupling strengths, the production rate of this channel can dominate top partner pair production at top partner masses of $m_T\gtrsim 1.5$ TeV. In addition, this model allows for the exotic decay modes $T\to tg$, $T\to t\gamma$, and $T\to tS$. In much of the parameter space the loop induced decay $T\to tg$ dominates and the top partner is quite long lived. New search strategies are necessary to cover these decay modes. We project the the sensitivity of the high luminosity LHC to $pp\to T\overline{t}+t\overline{T}$ via a realistic collider study. We find with 3 ab${}^{-1}$, the LHC is sensitive to this process for masses $m_T\lesssim 2$ TeV. In addition, we provide appendices detailing the renormalization of this model.

   hep-phJHEP(2018)·57 citations
8. 08*

   Maxwell-Higgs vortices with internal structure

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

   Vortices are considered in relativistic Maxwell-Higgs systems in interaction with a neutral scalar field. The gauge field interacts with the neutral field via the presence of generalized permeability, and the charged and neutral scalar fields interact in a way dictated by the presence of first order differential equations that solve the equations of motion. The neutral field may be seen as the source field of the vortex, and we study some possibilities, which modify the standard Maxwell-Higgs solution and include internal structure to the vortex.

   ↳ hep-thhep-phPLB(2018)·30 citations
9. 09*

   On the critical energy required for homogeneous nucleation in bubble chambers employed in dark matter searches

   G.Bruno🇮🇹 · N.Burgio🇮🇹 · M.Corcione🇮🇹 · L.Cretara🇮🇹 · M.Frullini🇮🇹 · W.Fulgione🇮🇹 · L.Manara🇮🇹 · A.Quintino🇮🇹 · A.Santagata🇮🇹 · L.Zanotti🇮🇹

   Two equations for the calculation of the critical energy required for homogeneous nucleation in a superheated liquid, and the related critical radius of the nucleated vapour bubble, are obtained, the former by the direct application of the first law of thermodynamics, the latter by considering that the bubble formation implies the overcoming of a barrier of the free enthalpy potential. Comparisons with the currently used relationships demonstrate that the sensitivity of the bubble chambers employed in dark matter searches can be sometimes notably overestimated.

   ↳ hep-exhep-phEPJC(2019)·2 citations
10. 10*

    Holographic meson decays via worldsheet instantons

    Kasper Peeters🇬🇧 · Maciej Matuszewski🇬🇧 · Marija Zamaklar🇬🇧

    We study meson decays using instanton methods in two string models. The first model is the old string model in flat space which combines strings and massive particles and the second is the holographic, Sakai-Sugimoto model. Using the the old string model, we reproduce the QCD formula for the probability of splitting of the QCD flux tube derived by Casher-Neuberger-Nussinov (CNN). In the holographic model we construct a string worldsheet instanton which interpolates between a single and double string configuration, which determines the decay from one to two dual mesonic particles. The resulting probability for meson decay incorporates both the effects of finite meson size as well as back-reaction of the produced quarks on the QCD flux tube. In the limit of very large strings the probability for a split reduces to the CNN formula. A byproduct of our analysis is the analysis of the moduli space of a generic double concentric Wilson loop with circles which are separated in the holographic direction of the confining background.

    ↳ hep-thhep-phJHEP(2018)·2 citations
11. 11*

    Black holes in quartic-order beyond-generalized Proca theories

    Ryotaro Kase🇯🇵 · Masato Minamitsuji🇵🇹 · Shinji Tsujikawa🇯🇵

    The generalized Proca theories with second-order equations of motion can be healthily extended to a more general framework in which the number of propagating degrees of freedom remains unchanged. In the presence of a quartic-order nonminimal coupling to gravity arising in beyond-generalized Proca theories, the speed of gravitational waves $c_t$ on the Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmological background can be equal to that of light $c$ under a certain condition. By using this condition alone, we show that the speed of gravitational waves in the vicinity of static and spherically symmetric black holes is also equivalent to $c$ for the propagation of odd-parity perturbations along both radial and angular directions. As a by-product, the black holes arising in our beyond-generalized Proca theories are plagued by neither ghost nor Laplacian instabilities against odd-parity perturbations. We show the existence of both exact and numerical black hole solutions endowed with vector hairs induced by the quartic-order coupling.

    ↳ gr-qcastro-ph.COhep-phhep-thPLB(2018)·28 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.