Publications de Mithilesh Nayak

Bound states and deconfined spinons in the dynamical structure factor of the J1-J2 spin-1 chain

Frédéric Mila, Henrik Moodysson Rønnow, Mithilesh Nayak

Using a time-dependent density matrix renormalization group approach, we study the dynamical structure factor of the J1-J2 spin-1 chain. As J2 increases, the magnon mode develops incommensurability. The system undergoes a first-order transition at J2=0.76J ...

2025

Field-induced bound-state condensation and spin-nematic phase in SrCu2(BO3)2 revealed by neutron scattering up to 25.9 T

Frédéric Mila, Bruce Normand, Henrik Moodysson Rønnow, Alexandra Angeline Turrini, Mithilesh Nayak, Ellen Fogh, Jian Rui Soh

In quantum magnetic materials, ordered phases induced by an applied magnetic field can be described as the Bose-Einstein condensation (BEC) of magnon excitations. In the strongly frustrated system SrCu2(BO3)(2), no clear magnon BEC could be observed, point ...

Nature Portfolio2024

Numerical investigation of bound states in quantum magnets

Mithilesh Nayak

Bound-states of particles are an interesting problem in quantum mechanics dating back to 1931 Bethe's solution of spin-1/2 Heisenberg chain. These exotic composite states are realized in quantum magnets and are detectable in inelastic neutron scattering (I ...

EPFL2023

Possibility to detect the bound state of the Heisenberg ferromagnetic chain at intermediate temperature

Frédéric Mila, Mithilesh Nayak

Motivated by the lack of direct evidence with inelastic neutron scattering of the well documented bound state of Heisenberg ferromagnets, we use the time-dependent thermal density matrix renormalization group algorithm to study the temperature dependence o ...

2022

Magnetic-Field-Induced Bound States in Spin-1/2 Ladders

Frédéric Mila, Mithilesh Nayak

Motivated by the recently observed intriguing mode splittings in a magnetic field with inelastic neutron scattering in the spin ladder compound (C5H12N)(2) CuBr4 (BPCB), we investigate the nature of the spin ladder excitations using a density matrix renorm ...

2020

Search for CP violation with kinematic asymmetries in the D-0 -> K+K- pi(+)pi(-) decay

Olivier Schneider, Sun Hee Kim, Tagir Aushev, Mingkui Wang, Chao Wang, Kyung Taek Cho, Jun Yong Kim, Mithilesh Nayak, Donghyun Kim, Yifei Guan, Lei Li, Ji Hyun Kim, Yiming Li, Xiao Wang

We search for CP violation in the singly-Cabibbo-suppressed decay D-0 -> K+K-pi(+)pi(-) using data corresponding to an integrated luminosity of 988 fb(-1) collected by the Belle detector at the KEKB e(+)e(-). We measure a set of five kinematically dependen ...

American Physical Society2019

Transverse momentum dependent production cross sections of charged pions, kaons and protons produced in inclusive e(+)e(-) annihilation at root s=10.58 GeV

Olivier Schneider, Sun Hee Kim, Tagir Aushev, Mingkui Wang, Chao Wang, Jun Yong Kim, Mithilesh Nayak, Donghyun Kim, Lei Li, Ji Hyun Kim, Yiming Li, Xiao Wang

We report measurements of the production cross sections of charged pions, kaons, and protons as a function of fractional energy, the event-shape variable called thrust, and the transverse momentum with respect to the thrust axis. These measurements access ...

American Physical Society2019

Search for the B -> Y(4260)K, Y(4260) -> J/psi pi(+)pi(-) decays

Olivier Schneider, Sun Hee Kim, Tagir Aushev, Mingkui Wang, Chao Wang, Yong Chan Choi, Kyung Taek Cho, Jun Yong Kim, Mithilesh Nayak, Linlin Cao, Carsten Hao Ye Chong, Donghyun Kim, Lei Li, Ji Hyun Kim, Yiming Li, Xiao Wang

We report the results of a search for the B -> Y(4260)K, Y(4260) -> J/psi pi(+)pi thorn p-decays. This study is based on a data sample corresponding to an integrated luminosity of 711 fb(-1), collected at the Upsilon(4S) resonance with the Belle detector a ...

American Physical Society2019

Search for a Light CP-odd Higgs Boson and Low-Mass Dark Matter at the Belle Experiment

Roberto Gargiani, Olivier Schneider, Sun Hee Kim, Tagir Aushev, Chao Wang, Hiroyasu Yamamoto, Yong Chan Choi, Seyed Sina Mirrazavi Salehian, Arnaud Michel Gelb, Ke Huang, Gaétan Charles Antoine Giriat, Jun Yong Kim, Mithilesh Nayak, Linlin Cao, Jiayun Shen, Tara Nanut, Donghyun Kim, Martin Lubej, Chang-Hyun Park, Lei Li, Ji Hyun Kim, Yiming Li

We report on the first Belle search for a light CP-odd Higgs boson, A(0), that decays into low mass dark matter, chi, in final states with a single photon and missing energy. We search for events produced via the dipion transition (sic)(2S) -> (sic)(1S)pi( ...

2019

Measurement of cos 2 beta in B-0 -> D((*))h(0) with D -> K-S(0)pi(+) pi(-) decays by a combined time-dependent Dalitz plot analysis of BABAR and Belle data

François Bianchi, Roberto Gargiani, Olivier Schneider, Sun Hee Kim, Tagir Aushev, Gerhard Raven, Mingkui Wang, Marilisa Neri, Liang Sun, Chao Wang, Taoufiq Harach, Songmei Wu, Yong Chan Choi, Greig Alan Cowan, Alexandra Bondarenko, Lorenzo Vitale, Arnaud Michel Gelb, Aaron James Rossini, Amaury Robert Dame, Gaétan Charles Antoine Giriat, Jun Yong Kim, Mithilesh Nayak, Jiayun Shen, Armend Gazmeno Hati, John Wilson, Tara Nanut, Donghyun Kim, Martin Lubej, Lei Li, Ji Hyun Kim, Yiming Li

We report measurements of sin 2 beta and cos 2 beta using a time-dependent Dalitz plot analysis of B-0 -> D((*))h(0) with D -> K-S(0)pi(+)pi(-) decays, where the light unflavored and neutral hadron h(0) is a pi(0),eta, or omega meson. The analysis uses a c ...

American Physical Society2018

Search for the rare decay of B+ -> l(+)nu e gamma with improved hadronic tagging

Roberto Gargiani, Olivier Schneider, Sun Hee Kim, Tagir Aushev, Mingkui Wang, Chao Wang, Hiroyasu Yamamoto, Taoufiq Harach, Yong Chan Choi, Seyed Sina Mirrazavi Salehian, Mia Primorac, Arnaud Michel Gelb, Tao Yang, Gaétan Charles Antoine Giriat, Mithilesh Nayak, Linlin Cao, Jiayun Shen, Donghyun Kim, Martin Lubej, Yiming Li, Xiao Wang

We present the result of the search for the rare B meson decay of B+ -> l(+)nu e gamma with l = e, mu. For the search the full data set recorded by the Belle experiment of 711 fb(-1) integrated luminosity near the Upsilon(4S) resonance is used. Signal cand ...

American Physical Society2018

First Evidence for cos 2 beta > 0 and Resolution of the Cabibbo-Kobayashi-Maskawa Quark-Mixing Unitarity Triangle Ambiguity

François Bianchi, Roberto Gargiani, Olivier Schneider, Sun Hee Kim, Tagir Aushev, Gerhard Raven, Mingkui Wang, Marilisa Neri, Liang Sun, Chao Wang, Taoufiq Harach, Songmei Wu, Yong Chan Choi, Greig Alan Cowan, Alexandra Bondarenko, Lorenzo Vitale, Seyed Sina Mirrazavi Salehian, Arnaud Michel Gelb, Aaron James Rossini, Amaury Robert Dame, Gaétan Charles Antoine Giriat, Jun Yong Kim, Mithilesh Nayak, Jiayun Shen, Armend Gazmeno Hati, John Wilson, Tara Nanut, Donghyun Kim, Martin Lubej, Lei Li, Ji Hyun Kim, Yiming Li

We present first evidence that the cosine of the CP-violating weak phase 2 beta is positive, and hence exclude trigonometric multifold solutions of the Cabibbo-Kobayashi-Maskawa (CKM) Unitarity Triangle using a time-dependent Dalitz plot analysis of B-0 -> ...

2018

Measurement of the branching fraction and time-dependent CP asymmetry for B-0 -> J/psi pi(0) decays

Roberto Gargiani, Olivier Schneider, Sun Hee Kim, Tagir Aushev, Mingkui Wang, Chao Wang, Taoufiq Harach, Yong Chan Choi, Arnaud Michel Gelb, Tao Yang, Gaétan Charles Antoine Giriat, Mithilesh Nayak, Linlin Cao, Jiayun Shen, Donghyun Kim, Lei Li, Yiming Li, Xiao Wang

We measure the branching fraction and time-dependent CP-violating asymmetry for B-0 -> /psi pi(0) decays using a data sample of 711 fb(-1) collected on the Gamma(4S) resonance by the Belle experiment running at the KEKB e(+)e(-) collider. The branching fra ...

American Physical Society2018