The report said cutting the higher rate from 40% to 30% would bring in about £500m extra a year after 10 years.
The higher rate is currently paid on annual taxable income of between £43,001 and £150,000.
Control over income tax is due to be split between UK and Welsh ministers, once an agreement can be reached.
The report, by Prof James Foreman-Peck and Dr Peng Zhou, assumed no change in England's tax rates.
Although they predicted tax income in Wales could fall in the first three years after a cut, the authors said receipts should rise in the longer term as high earners find it worthwhile to move from England.
"The encouragement to some households to immigrate, increasing Welsh taxable income, is greater than the revenue lost from the reduction in the rate", the report said.
For the top earners with income of more than £150,000 a year - about one in 100 UK residents - a cut in the additional 45% rate should also boost tax income in Wales, it added.
But the report said cutting the basic 20% rate would not boost migration sufficiently to make up for the lost revenue from existing taxpayers in Wales.
Welsh Conservative leader Andrew RT Davies has said he would like to see a 5p cut in the higher 40% rate of tax and a 2p cut in the basic 20% rate, although the party's manifesto for May's assembly election did not include these figures.
He said this research "reignites the debate about tax devolution", adding: "A Welsh Government with the courage to cut income tax rates could reinvigorate the Welsh economy, whist offering welcome support to hardworking families."

Mr Duterte clarified that he had "nothing against gays", saying several of his relatives were homosexual.
The controversial politician had previously appeared supportive of LGBTQ rights, saying in 2015 that same-sex marriage was "good".
But he is otherwise known for his conservative views especially on crime.
He has waged a much-criticised war on drug users and dealers leading to thousands of extra-judicial killings.
His latest remarks were made on Sunday night to Filipino expatriates in the Burmese capital of Nay Pyi Taw while on an official trip to Myanmar. A transcript of the speech was only given to journalists on Monday.
In a meandering speech addressing criticism of his now-suspended war on drugs, Mr Duterte accused the West of imposing its values on the Philippines, then referred to a recent Time magazine story on the transgender community in the US.
"There is no gender because you can be a he or she... That's their culture. It does not apply to us. We are Catholics and there is the Civil Code, which says that you can only marry a woman for me... a woman to marry a man.
"That's our law so why would you accept that gender?" he said.
"Wherever God placed you, just remain there. Do not mix it upâ€¦ You erase the great divide between a woman and a man," he added.
Before becoming president in June 2016, Mr Duterte was the mayor of Davao city, which introduced anti-discrimination laws for sex, gender and sexual orientation during his administration.
In 2015, Mr Duterte appeared on a national talk show where he said same-sex marriage was "good... everyone deserves to be happy".
The following year, while campaigning for the presidency, he said he would "consider" legalising same-sex marriage if there was such a proposal.
The Philippines has 80 million Catholics and remains a deeply religious society.
Mr Duterte has taken issue with the church previously, once calling the Pope a "son of a whore".
Despite his many controversial comments he still remains highly popular in the Philippines.

AFB was confirmed at the apiary at Scaniport, near Inverness, on Friday.
There is no permitted treatment in the UK for the disease, which kills bee larvae.
The Scottish government said there was a ban in place on the movement of bees and related equipment from the affected area.
Reducing the higher rate of income tax in Wales would raise additional revenue by attracting high earners, according to research by Cardiff Business School.
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Philippine President Rodrigo Duterte has said he opposes gay marriage, after previously declaring he would consider legalising it.
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A hive of honey bees has been destroyed at an apiary in the Highlands after the insects were found to be infected with the disease, American Foulbrood (AFB).