Mon·Feb 6, 2017Monday·February 6, 2017

1. 01*

   Precision Tests and Fine Tuning in Twin Higgs Models

   Roberto Contino🇮🇹 · Davide Greco🇨🇭 · Rakhi Mahbubani🇨🇭 · Riccardo Rattazzi🇨🇭 · Riccardo Torre🇨🇭

   We analyze the parametric structure of Twin Higgs (TH) theories and assess the gain in fine tuning which they enable compared to extensions of the Standard Model with colored top partners. Estimates show that, at least in the simplest realizations of the TH idea, the separation between the mass of new colored particles and the electroweak scale is controlled by the coupling strength of the underlying UV theory, and that a parametric gain is achieved only for strongly-coupled dynamics. Motivated by this consideration we focus on one of these simple realizations, namely composite TH theories, and study how well such constructions can reproduce electroweak precision data. The most important effect of the Twin states is found to be the infrared contribution to the Higgs quartic coupling, while direct corrections to electroweak observables are sub-leading and negligible. We perform a careful fit to the electroweak data including the leading-logarithmic corrections to the Higgs quartic up to three loops. Our analysis shows that agreement with electroweak precision tests can be achieved with only a moderate amount of tuning, in the range 5-10\%, in theories where colored states have mass of order 3-5 TeV and are thus out of reach of the LHC. For these levels of tuning, larger masses are excluded by a perturbativity bound, which makes these theories possibly discoverable, hence falsifiable, only at a future 100 TeV collider.

   hep-phPRD(2017)·48 citations
2. 02*

   Associated production of a top pair and a Z boson at the LHC to NNLL accuracy

   Alessandro Broggio🇩🇪 · Andrea Ferroglia🇺🇸 · Giovanni Ossola🇺🇸 · Ben D. Pecjak🇬🇧 · Ray D. Sameshima🇺🇸

   We study the resummation of soft gluon emission corrections to the production of a top-antitop pair in association with a Z boson at the Large Hadron Collider to next-to-next-to-leading logarithmic accuracy. By means of an in-house parton level Monte Carlo code we evaluate the resummation formula for the total cross section and several differential distributions at a center-of-mass energy of 13 TeV, and we match these calculations to next-to-leading order results.

   hep-phJHEP(2017)·47 citations
3. 03*

   Unveiling saturation effects from nuclear structure function measurements at the EIC

   Cyrille Marquet🇫🇷 · Manoel R. Moldes🇪🇸 · Pía Zurita🇺🇸

   We analyze the possibility of extracting a clear signal of non-linear parton saturation effects from future measurements of nuclear structure functions at the Electron-Ion Collider (EIC), in the small-x region. Our approach consists in generating pseudodata for electron-gold collisions, using the running-coupling Balitsky-Kovchegov evolution equation, and in assessing the compatibility of these saturate pseudodata with existing sets of nuclear parton distribution functions (nPDFs), extrapolated if necessary. The level of disagreement between the two is quantified by applying a Bayesian reweighting technique. This allows to infer the parton distributions needed in order to describe the pseudodata, which we find quite different from the actual distributions, especially for sea quarks and gluons. This tension suggests that, should saturation effects impact the future nuclear structure function data as predicted, a successful refitting of the nPDFs may not be achievable, which would unambiguously signal the presence of non-linear effects.

   hep-phPLB(2017)·25 citations
4. 04*

   New-Type Charged Q-ball Dark Matter in Gauge Mediated SUSY Breaking Models

   Jeong-Pyong Hong🇯🇵 · Masahiro Kawasaki🇯🇵

   We examined the viability of new-type charged Q-ball dark matter scenario. We considered the case where the relics can be treated as ordinary ions, to which we applied the observational constraint from MICA experiment, where no trail of heavy ion-like object is observed in $10^9$ years old ancient muscovite mica. We have found that the allowed parameter region exists but is smaller than the neutral Q-ball dark matter case. We have also discussed whether our scenario is actually consistent with Affleck-Dine mechanism.

   hep-phPRD(2017)·13 citations
5. 05*

   Renormalization Group Running in the Symmetric and the Broken Symmetry Phases of the $R_{\xi }$ and the $\overline{R_{\xi }}$ Gauges

   Chungku Kim🇰🇷

   We investigate the renormalization group (RG) running of the effective potential and the pole mass in the broken symmetry phase of the $R_{\xi }$ and the $\overline{R_{\xi }}$ gauges which have different RG running for the effective potential in the symmetric phase and show that if the vacuum expectation value (VEV) is expressed as a function of the other parameters of the theory by solving the minimization condition, then the effective potential in the broken symmetry phase in both gauges satisfies the same RG equation as one in the symmetric phase of the $\overline{R_{\xi }}$ gauge. The pole masses in the broken symmetry phase of both gauges are RG invariant with respect to the RG funtions of the symmetric phase and are shown to be the same at one-loop order.

   hep-phJ.Korean Phys.Soc.(2016)·2 citations
6. 06*

   Photon emission and decay from generic Lorentz Invariance Violation

   H. Martínez-Huerta🇲🇽 · A. Pérez-Lorenzana🇲🇽

   One of the most studied approaches in phenomenology to introduce the breaking of Lorentz symmetry is the generic approach. This consist on the modification of the free particle dispersion relation by the addition of an extra power law term of order $n$ on energy or momentum. Using this approach in the photon sector, we have calculated the generic rates for vacuum Cherenkov radiation and photon decay, for any order $n$, at leading order. Explicit results for the decay and emission rates for the lowest values of $n$ are also presented.

   hep-phastro-ph.HEJ.Phys.Conf.Ser.(2017)·12 citations
7. 07*

   Radiative breaking of conformal symmetry in the Standard Model

   A.B. Arbuzov🇷🇺 · R.G. Nazmitdinov🇷🇺 · A.E. Pavlov🇷🇺 · V.N. Pervushin🇷🇺 · A.F. Zakharov🇷🇺

   Radiaitve mechanism of conformal symmetry breaking in a comformal-invariant version of the Standard Model is considered. The Coleman-Weinberg mechanism of dimensional transmutation in this system gives rise to finite vacuum expectation values and, consequently, masses of scalar and spinor fields. A natural bootstrap between the energy scales of the top quark and Higgs boson is suggested.

   hep-phhep-thEPL(2016)·6 citations
8. 08*

   Transition Radiation by Neutrinos at an Edge of Magnetic Field

   A. Ioannisian🇦🇲 · N. Kazarian🇦🇲

   We calculate the transition radiation process $\nu \to \nu \gamma$ at an interface of magnetic field and vacuum. The neutrinos are taken to be with only standard-model couplings. The magnetic field fulfills the dual purpose of inducing an effective neutrino-photon vertex and of modifying the photon dispersion relation. The transition radiation occurs when at least one of those quantities have different values in different media. The neutrino mass is ignored due to its negligible contribution. We present a result for the probability of the transition radiation which is both accurate and analytic.

   hep-ph2 citations
9. 09*

   Constraining Higgs boson effective couplings at electron-positron colliders

   Hamzeh Khanpour🇮🇷 · Mojtaba Mohammadi Najafabadi🇮🇷

   We probe the dimension-six operators contributing to Higgs production in association with a $Z$ boson at the future high-luminosity electron-positron colliders. Potential constraints on dimension-six operators in the Higgs sector are determined by performing a shape analysis on the differential angular distribution of the Higgs and $Z$ boson decay products. The analysis is performed at the center-of-mass energies of 350 and 500 GeV including a realistic detector simulation and the main sources of background processes. The 68\% and 95\% confidence level upper limits are obtained on the contributing anomalous couplings considering only the decay of the Higgs boson into a pair of $b$-quarks and leptonic $Z$ boson decay. Our results show that angular observables provide a great sensitivity to the anomalous couplings, in particular, at the high-luminosity regime.

   hep-phPRD(2017)·46 citations
10. 10*

    Point-by-point extraction of parton distribution functions from SIDIS single transverse-spin asymmetries

    Anna Martin🇮🇹 · Franco Bradamante🇮🇹 · Vincenzo Barone🇮🇹

    We show how some parton distribution functions related to the transverse spin of nucleons can be extracted point by point from combinations of proton and deuteron observables. In particular, we present a determination of the valence and sea Sivers functions from the single-spin asymmetries measured by COMPASS.

    hep-ph1 citation
11. 11*

    Reheating, thermalization and non-thermal gravitino production in MSSM inflation

    Andrea Ferrantelli🇫🇮

    In the framework of MSSM inflation, matter and gravitino production are here investigated through the decay of the fields which are coupled to the udd inflaton, a gauge invariant combination of squarks. After the end of inflation, the flat direction oscillates about the minimum of its potential, losing at each oscillation about 56% of its energy into bursts of gauge/gaugino and scalar quanta when crossing the origin. These particles then acquire a large inflaton VEV-induced mass and decay perturbatively into the MSSM quanta and gravitinos, transferring the inflaton energy very efficiently via instant preheating. Regarding thermalization, we show that the MSSM degrees of freedom thermalize very quickly, yet not immediately by virtue of the large vacuum expectation value of the inflaton, which breaks the $SU(3{)}_C\times U(1{)}_Y$ symmetry into a residual $U(1)$. The energy transfer to the MSSM quanta is very efficient, since full thermalization is achieved after only $\mathcal{O}(40)$ complete oscillations. The udd inflaton thus provides an extremely efficient reheating of the Universe, with a temperature $T_{reh}=\mathcal{O}(10^8\mathrm{GeV})$ that allows for instance several mechanisms of baryogenesis. We also compute the gravitino number density from the perturbative decay of the flat direction and of the SUSY multiplet. We find that the gravitinos are produced in negligible amount and satisfy cosmological bounds such as the Big Bang Nucleosynthesis (BBN) and Dark Matter (DM) constraints.

    hep-phastro-ph.COgr-qchep-thEPJC(2017)·7 citations
12. 12*

    Inclusive Semitauonic $B$ Decays to Order $\mathcal{O}({\Lambda }_{QCD}^3/m_b^3)$

    Thomas Mannel🇩🇪 · Aleksey V. Rusov🇩🇪 · Farnoush Shahriaran🇩🇪

    We calculate the decay width and the $\tau$-lepton energy distribution as well as relevant moments for inclusive $\bar{B}\to X_c\tau {\bar{\nu }}_{\tau }$ process including power corrections up to order ${\Lambda }_{QCD}^3/m_b^3$ and QCD corrections to the partonic level. We compare the result with the sum of the standard-model predictions of the branching fractions of the exclusive semileptonic $\bar{B}\to (D,D^{\ast },D^{\ast \ast })\tau {\bar{\nu }}_{\tau }$ decays as well as with the relevant experimental data. Our prediction is in agreement with the LEP measurement and is consistent with the standard-model calculation of the exclusive modes. We discuss the impact from physics beyond the Standard Model.

    hep-phNPB(2017)·48 citations
13. 13*

    A light $Z^{\prime }$ for the $R_K$ puzzle and nonstandard neutrino interactions

    Alakabha Datta🇺🇸 · Jiajun Liao🇺🇸 · Danny Marfatia🇺🇸

    We show that the $R_K$ puzzle in LHCb data and the discrepancy in the anomalous magnetic moment of the muon can be simultaneously explained if a 10 MeV mass $Z^{\prime }$ boson couples to the muon but not the electron, and that clear evidence of the nonstandard matter interactions of neutrinos induced by this coupling may be found at DUNE.

    hep-phhep-exPLB(2017)·61 citations
14. 14*

    On the upper bound of entropy production rate from particle multiplicity in heavy ion collisions

    Mateusz Ploskon (LBNL, Berkeley)🇺🇸 · Martin Veselsky (SAOS, Bratislava)🇸🇰

    We provide a simple derivation for particle production in heavy-ion collisions that is proportional to the rate of entropy production. We find that the particle production depends only on the power of the centre-of-mass collision energy $\sqrt{s_{\mathrm{NN}}}$ and the effective phase-space/volume (e.g. geometry of the collision approximated by the number of nucleons participating in the collision $N_{\mathrm{part}}$). We show that at low-energies the pseudo-rapidity density of particles per participating nucleon pair scales linearly with $\sqrt{s_{\mathrm{NN}}}$ while at high-energies with ${\sqrt{s_{\mathrm{NN}}}}^{1/3}$. The ${\sqrt{s_{\mathrm{NN}}}}^{1/3}$ region is directly related to sub-nucleon degrees of freedom and creation of a quark-gluon plasma (QGP). This picture explains experimental observation that the shape of the distributions of pseudorapidity-density per nucleon pair of charged particles does not depend on $\sqrt{s_{\mathrm{NN}}}$ over a large span of collision energies. We provide an explanation of the scaling and connect it with the maximum rate per unit time of entropy production. We conclude with remarks on the hadron-parton phase transition. In particular, our considerations suggest that the pseudo-rapitidy density of the produced particles per $N_{\mathrm{part}}/2$ larger than approximately 1 (excluding particles from jet fragmentation) is a signature of a QGP formation.

    hep-phhep-exnucl-exnucl-th2 citations
15. 15*

    Bayesian analysis for a new class of hybrid EoS models using mass and radius data of compact stars

    A. Ayriyan🇷🇺 · D. E. Alvarez-Castillo🇷🇺 · S. Benic🇯🇵 · D. Blaschke🇷🇺 · H. Grigorian🇷🇺 · S. Typel🇩🇪

    We present a Bayesian analysis for a new class of realistic models of two-phase equations of state (EoS) for hybrid stars and demonstrate that the observation of a pair of high-mass twin stars would have a sufficient discriminating power to favor hybrid EoS with a strong first order phase transition over alternative EoS. Such a measurement would provide evidence for the existence of a critical endpoint in the QCD phase diagram.

    ↳ astro-ph.HEhep-phnucl-thActa Phys.Polon.Supp.B(2017)·4 citations
16. 16*

    Constraining the hadronic spectrum through QCD thermodynamics on the lattice

    Paolo Alba🇩🇪 · Rene Bellwied🇺🇸 · Szabolcs Borsanyi🇩🇪 · Zoltan Fodor🇩🇪 · Jana Guenther🇩🇪 · Sandor D. Katz🇭🇺 · Valentina Mantovani Sarti🇮🇹 · Jacquelyn Noronha-Hostler🇺🇸 · Paolo Parotto🇺🇸 · Attila Pasztor🇩🇪 · Israel Portillo Vazquez🇺🇸 · Claudia Ratti🇺🇸

    Fluctuations of conserved charges allow to study the chemical composition of hadronic matter. A comparison between lattice simulations and the Hadron Resonance Gas (HRG) model suggested the existence of missing strange resonances. To clarify this issue we calculate the partial pressures of mesons and baryons with different strangeness quantum numbers using lattice simulations in the confined phase of QCD. In order to make this calculation feasible, we perform simulations at imaginary strangeness chemical potentials. We systematically study the effect of different hadronic spectra on thermodynamic observables in the HRG model and compare to lattice QCD results. We show that, for each hadronic sector, the well established states are not enough in order to have agreement with the lattice results. Additional states, either listed in the Particle Data Group booklet (PDG) but not well established, or predicted by the Quark Model (QM), are necessary in order to reproduce the lattice data. For mesons, it appears that the PDG and the quark model do not list enough strange mesons, or that, in this sector, interactions beyond those included in the HRG model are needed to reproduce the lattice QCD results.

    ↳ hep-lathep-phnucl-thPRD(2017)·154 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.